CN100480736C - MgF2 optical thin film, optical device having the same, and method for producing the MgF2 optical thin film - Google Patents

MgF2 optical thin film, optical device having the same, and method for producing the MgF2 optical thin film Download PDF

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CN100480736C
CN100480736C CNB2005800250665A CN200580025066A CN100480736C CN 100480736 C CN100480736 C CN 100480736C CN B2005800250665 A CNB2005800250665 A CN B2005800250665A CN 200580025066 A CN200580025066 A CN 200580025066A CN 100480736 C CN100480736 C CN 100480736C
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mgf
thin film
film
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optical thin
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CN1989427A (en
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石泽均
新坂俊辅
村田刚
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Nikon Corp
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Nikon Corp
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Abstract

An MgF 2 optical thin film 100 is formed on an optical surface of a base material 10. The MgF 2 optical thin film 100 includes MgF 2 particles 12 and an amorphous silicon oxide-based binder 13 which exists on the surfaces of the MgF 2 particles and between the MgF 2 particles. Owing to this amorphous silicon oxide-based binder 13, the optical thin film 100 can have high mechanical strength and high adhesion to the base material 10, while having excellent environment resistance and a lower refractive index.

Description

MgF 2Optical thin film and the manufacture method that possesses optical module and this film of this film
Technical field
The invention provides a kind of MgF of using 2The optical thin film and the manufacture method thereof of the single or multiple lift that forms, and have MgF 2The optical module of optical thin film and the employed optical system of optical apparatus of loading the camera, microscope, binoculars, exposure device etc. of this optical module.
Background technology
On each lens surface that constitutes optical systems such as camera eyeglass or micro objective, be coated with anti-reflective film in order to reduce reflection.Generally speaking, the optical thin film of anti-reflective film etc. is made with dry process (dry process), and it can use vacuum vapour deposition, sputtering method, CVD methods such as (Chemical Vapor Deposition).
In order in wide wavelength coverage or extensive angle scope, to obtain having the high-performance optics film of antiradar reflectivity, as long as known most the coating materials that will have different refractivity are combined to form multilayer film.Utilizing dry process to form in the situation of anti-reflective film general using TiO 2As maximum refractive index material (refractive index of 500nm is 2.4～2.7); Utilize MgF 2As lowest refractive index material (refractive index of 500nm is 1.38).
Generally speaking, multilayer film, it strengthens the refringence of coating material or uses low refractive index film in the superiors, promotes optical property by this, even or the identical quantity that also can reduce coating layer of optical property.Especially, utilize emulation as can be known, only the superiors adopt the low refractive index film of refractive index below 1.30, can significantly promote optical property.Promptly, only the superiors adopt the low refractive index film of refractive index below 1.30, can suppress reflectivity very low in wide wavelength coverage, help to make it broadbandization, and not only to vertical incidence light, still can suppress to very low, and help incident angle extensively to change its reflectivity of light by the incident of extensive angle scope institute.Therefore, need to make the technology of refractive index in the industry at the optical thin film below 1.30.
Effectively reduce the practice of the refractive index of film, be not the compact structure that makes film, but make it to become porous matter.Generally speaking, because a plurality of small hole of the solid matter that film forms across accumulation between having, so the relation of the packed density of film and refractive index is as described below:
n f＝n o×P+n p×(1-P)
Wherein, n pBe the refractive index of the material (as air or water) that fills up small hole, n fWith n oBe respectively actual refractive index (becoming with packed density) and pile up the solid material refractive index that forms, P is the filling rate of film.In addition, filling rate defines with following:
P=(volume of the solid portion of film)/(cumulative volume of film (solid portion+micro hole cavity portion)), thus, the height of packed density promptly means the height of refractive index.
Generally speaking, more suitable in order to obtain fine and close film with dry processes such as evaporation or sputters, in order to obtain the film of porous matter, then more suitable with damp process (wet process).So-called wet process is to utilize rotary coating, dip coating, spray-on process, rolling method etc., by liquid being coated on the substrate and carrying out drying, thermal treatment and the method for film forming.Advantage can as: different with dry process, do not need large-scale device, and since can be in atmosphere film forming, so cost can significantly reduce.Moreover, in the little lens of radius-of-curvature, be difficult for being coated with optical thin film equably with dry processes such as vacuum vapour deposition or sputtering methods, utilize wet process such as spin-coating method more easily to carry out, even the little curved surface of large tracts of land or radius-of-curvature also can be equably film forming thereon.
In following patent documentation 1, disclosed and utilized wet process to make porous matter MgF 2The method of film.This method is to utilize under High Temperature High Pressure MgF 2Sol solution heat-treat, make MgF 2Particulate carries out being coated with and film forming behind particle growth and the crystallization again.Utilize this method, i.e. order MgF 2Particulate is piled up and film forming, also can not destroy the pore between particulate and can guarantee high porosity.Its result, film becomes porous matter, and compared to the dense film of utilizing the dry process manufacturing, can reduce refractive index significantly.Yet, resulting multiple aperture plasma membrane physical strength low and with the poor adhesive force of substrate, in case through wiping, multiple aperture plasma membrane is promptly peeled off.
Known existing many technology of using various its adhesion of atomic multiple aperture plasma membrane and film strength of improving.As in following patent documentation 2, disclosing, strengthen and penetrate the SnO that is coated with on the striped tube-surface at negative electrode 2The technology of the antistatic film that particulate constituted.In this technology, by utilizing wet process at SnO 2Form SiO on the film 2Film makes SnO 2Film has enough intensity.Yet, owing to form fine and close SiO in the superiors 2Film is so can't reduce refractive index.
In following patent documentation 3, disclose the example of strengthening the method for multiple aperture plasma membrane itself, strengthened the technology of the multiple aperture plasma membrane of being formed by inorganic fine particles with the bond of polymkeric substance.In this technology, though but reinforced film itself, because the refractive index of polymkeric substance is higher, so the refractive index of film can't be reduced to below 1.3.
Moreover, in following patent documentation 4 and 5, disclosed with the bond of alkoxy silane and strengthened by SiO 2The technology of the multiple aperture plasma membrane that particulate constituted.But though also reinforced film of this technology itself, SiO 2Character with the moisture in the easy absorbed air, and,, and cause serious wavelength shift so surface area is big because film is a porous matter.Therefore, though can be used for the anti-reflective film of display equipment, be difficult for being used on the precision optical instruments such as camera or microscope.
Wavelength shift can use the colloidal sol of being put down in writing as following patent documentation 6 to suppress.In the document, put down in writing with cataloid and MgF 2The colloidal sol of the composite colloid particle of 5～50nm that the aggegation of hydrate institute forms is as the smears.Though there is no record, in the situation that forms film, because MgF about film 2Has the character that is difficult for adsorption moisture, so be difficult for causing wavelength shift.Yet, as above-mentioned colloidal sol in owing to have a non-persistent MgF 2Hydrate but not simple MgF 2, may not have good environment resistant.
Recently, optical system makes it day by day complicated and diversified along with its lifting that requires performance.For example, in order to make aberration approach its limit or to promote the multiplying power etc. of zoom, cause the increase of number of lenses.Moreover, make towards the big design of the angle of incidence of light degree change of lens face also very necessary.In addition, in recent years, because digital camera becomes popular, so far, film is replaced as photography assemblies such as so-called CCD or CMOS gradually.
When considering the change of these optical systems by the viewpoint of surface reflections such as lens, the increase of lens is the increase of reflecting surface, though be suitable for general anti-reflective film,, and also make penetrance descend because of ghost image (ghost) that residual reflection caused or the generation probability of dazzle uprise.Moreover, about the increase of incident angle, so-called surface reflection, in theory with have or not anti-reflective film irrelevant, oblique incidence, its surface reflection has the tendency that becomes big, and becomes the reason of ghost image or dazzle.The reflection of photography assembly is the key element that is not considered up to now so, and existing people points out that its reflected light will get back to optical system and cause dazzle or ghost image.This ghost image or dazzle cause contrast to descend or the colourity variation, will cause image to disappear when serious, so undesirable.
Though general employed anti-reflective film also is the anti-reflective film of individual layer in the early stage now, yet for wavelength coverage is broadened, and develop into the anti-reflective film of multilayer by the anti-reflective film of individual layer, a lot of time have been descended at aspects such as adjusting antireflective properties by the raising production technology, and in optical design, consider how suitably to dispose anti-reflective film, the restriction incident angle works hard to avoid causing aspects such as variety of issue, its result can produce the few lens of problem (with reference to patent documentation 7).
But above-mentioned is could set up under the prerequisite of sacrificing the optics design freedom, and when the situation of novel components such as requirement that faces the high performance of as above stating record or employing CCD, anti-reflective film performance so far still dislikes not enough as can be known.
[patent documentation 1] is international to be disclosed 02/18982A1 number
No. the 3272111st, [patent documentation 2] Japan special permission
[patent documentation 3] Japanese kokai publication hei 11-6902 communique
[patent documentation 4] Japanese kokai publication hei 7-48527 communique
[patent documentation 5] Japanese kokai publication hei 8-122501 communique
[patent documentation 6] TOHKEMY 2000-169133 communique
[patent documentation 7] Japanese kokai publication sho 62-124503 communique
Summary of the invention
Yet, to use MgF as above-mentioned patent documentation 1 2Film, even the refractive index of optical thin film can be reduced to below 1.30 but film strength or not good with the adhesion of base material; Moreover, for as above-mentioned patent documentation 2 to 6 can guarantee film strength and with the film of the adhesion of base material, the refractive index of film can't be reduced to very low, and so-called environment resistant not good problem arranged, can't obtain in addition refractive index can reduce to low-down optical thin film and can guarantee film physical strength and with the adhesion of base material, guarantee environment resistant problems such as optical thin film simultaneously.
If utilize dry process such as vapour deposition method, can be coated with the multi-layer anti-reflective film of high refractive index film and the mutual lamination of low refractive index film, but with wet process, multi-layer coated and be not easy.Therefore, utilize in the situation of wet process film forming, generally speaking, form anti-reflective film with individual layer.In the situation of individual layer, if making the refractive index of film is the square root of substrate refractive index, then can make reflectivity in theory is 0%.
Therefore, for the different various optical glass of refractive index, as long as can make the refractive index of anti-reflective film produce slight variations, get final product manufacturing property camera lens or object lens etc. preferably, therefore be badly in need of adjusting the technology of film refractive index corresponding to the lens material of various refractive indexes.
About the adjustment of the refractive index of film,, be easy to make this multiple aperture plasma membrane to become fine and close and refractive index is heightened based on the film of porous matter and low-refraction.Otherwise if desire to make compact substance and the high person of refractive index to become porous matter and reduce refractive index, then film itself crumbles most probably, and historical facts or anecdotes is now got up very difficult.Therefore, in order to adjust refractive index, need refractive index can reduce to low-down multiple aperture plasma membrane especially.
About the low-down multiple aperture plasma membrane of refractive index, the use MgF of promptly above-mentioned patent documentation 1 2Film, as long as with porous matter MgF 2Film carries out high-temperature heat treatment, can promote the adhesion between particulate and improve film itself intensity and with the adhesion of substrate.Yet, if can't not obtain significant effect heat-treating promptly more than 300 ℃, but will make film become fine and close, and refractive index will become greatly, and the fluorine of fluoride may break away from and becomes oxide in the thermal treatment that high temperature carries out multiple aperture plasma membrane.Moreover because substrate process pyroprocessing, the precision of optical grinding face will change, and refractive index also changes, and the substrate of poor heat resistance also may break.
Moreover, in employed technology of optical thin film or design, utilize multiple stratification to reach broadbandization at most so far, keeping under the state of this wavelength coverage, almost be the antiradar reflectivity that impossible reach absolute or reflectivity is reduced.
Therefore, first purpose of the present invention be to provide a kind of physical strength high and with the MgF of the strong adhesion of substrate, the environment resistant good and low-refraction that is easy to get 2Optical thin film.
Moreover second purpose of the present invention is to provide can make this MgF with comparalive ease 2The manufacture method of optical thin film, and the MgF that is fit to this manufacture method further is provided 2Sol solution.
Moreover the 3rd purpose of the present invention is to provide a kind of MgF 2The manufacture method of optical thin film, it can more easily adjust MgF 2The refractive index of optical thin film.
Moreover the 4th purpose of the present invention is to provide under a kind of maintenance broadbandization, can reach the absolute antiradar reflectivity or multi-layer anti-reflective film, optical module and the optical system of the reduction of the reflectivity under high incident angle.
Description of drawings
Fig. 1: the summary enlarged cross section figure of the optical module of first example;
Fig. 2: the optical system that shows first example;
Fig. 3: according to embodiment 1 resulting MgF 2-SiO 2The cross section of optical thin film and surperficial electron micrograph;
Fig. 4: according to embodiment 7 resulting MgF 2-SiO 2The cross section of optical thin film and surperficial electron micrograph;
Fig. 5: expression embodiment 29 manufacturings MgF is set on resin bed 2-SiO 2The branch reflective character of the optical module of optical thin film;
Fig. 6: the branch reflective character of the multilayer optical film of expression embodiment 34;
Fig. 7: the branch reflective character of the multilayer optical film of expression embodiment 35;
Fig. 8: the summary sectional view of representing the optical module of second example of the present invention;
Fig. 9: the summary sectional view of the optical module of expression embodiments of the invention 36;
Figure 10: expression light vertical incidence is during to the multi-layer anti-reflective film of the embodiment of the invention 36, the graph of a relation of its wavelength and reflectivity;
Figure 11: represent light with 30 degree, when 45 degree, 60 are spent and are incident to the multi-layer anti-reflective film of the embodiment of the invention 36, the graph of a relation of its wavelength and reflectivity;
Figure 12: compared to embodiments of the invention 36, the figure corresponding to Figure 10 of comparative example 5;
Figure 13: compared to embodiments of the invention 36, the figure corresponding to Figure 11 of comparative example 5;
Figure 14: the substrate refractive index is 1.46 o'clock figure corresponding to Figure 10 in the embodiment of the invention 37;
Figure 15: the substrate refractive index is 1.62 o'clock figure corresponding to Figure 10 in the embodiment of the invention 37;
Figure 16: the substrate refractive index is 1.74 o'clock figure corresponding to Figure 10 in the embodiment of the invention 37;
Figure 17: the substrate refractive index is 1.85 o'clock figure corresponding to Figure 10 in the embodiment of the invention 37.
Symbol description
10---base material 11---MgF 2Optical thin film 12---MgF 2Particulate
13---amorphous silicon oxide binder 14---space
112---multi-layer anti-reflective film 118---imaging optical system
L1～L12---lens
Embodiment
According to first form of the present invention, provide a kind of MgF 2Optical thin film, it has MgF 2Particulate be present in MgF 2Amorphous silicon oxide binder between particulate.
According to the present invention, because it is with environment resistant (permanance) good MgF 2Particulate is as the major component material of film, and with this MgF 2Utilize amorphous silicon oxide binder to link between particulate, so can strengthen MgF 2Between particulate and MgF 2Combining between particulate and base material, and promote the physical strength of film and the adhesion between film and base material.Also promptly, it has at MgF 2Exist the space between particulate and in this space, fill the structure of amorphous silicon oxide binder.Can use environment resistant poor slightly SiO 2As amorphous silicon oxide binder, because to MgF 2Particulate only needs a small amount of bond promptly enough, so for film integral, can guarantee fully that it is environment resistant.
At MgF of the present invention 2In the optical thin film, at aforementioned MgF 2Utilize amorphous silicon oxide binder to link between particulate, and be present in MgF 2The outmost MgF of particulate 2The lip-deep amorphous silicon oxide binder of particulate, making its thickness is below 5% of optical wavelength that is shone.In addition, MgF of the present invention 2Optical thin film is present in adjacent described MgF 2Amorphous silicon oxide binder thickness between particulate, comparable this MgF 2Atomic particle diameter is little.By utilizing aforesaid way to adjust the thickness of bond, can reduce refractive index.Especially, it is very low that the outermost refractive index of optical thin film is reduced to, and can obtain having in wide wavelength coverage and extensive angle scope the anti-reflective film of antiradar reflectivity.
Moreover, in the present invention, need be at all MgF 2All has amorphous silicon oxide binder between particulate, the MgF that needs only in some 2Has amorphous silicon oxide binder between particulate to keep MgF 2The particulate film is promptly enough.In addition, need be at MgF 2Has amorphous silicon oxide binder between particulate and base material fully, as long as by MgF in some 2Have amorphous silicon oxide binder between particulate and base material, utilize amorphous silicon oxide binder to strengthen MgF 2The binding of particulate and base material is promptly enough.
At MgF of the present invention 2In the optical thin film, aforementioned MgF 2Atomic mean grain size can be 1nm～100nm (more than the 1nm, below the 100nm).At this, because MgF 2Atomic crystallinity height is so can suppress MgF 2Particulate is adhered mutually and is guaranteed at MgF 2Space between particulate, and can obtain the MgF of porous structure 2Optical thin film.Utilization has porous structure and can obtain the lower MgF of refractive index 2Optical thin film.From guaranteeing the viewpoint of film strength, the voidage of aforementioned porous structure can be below 50%.
At MgF of the present invention 2In the optical thin film, aforementioned amorphous silicon oxide binder can be formed and obtained by amorphous silica.At this, because its refractive index of amorphous silica lower (1.42), so even itself and MgF 2The particulate combination also can be guaranteed the low-refraction of film integral.
Utilize the micro-indentations method of testing to measure MgF of the present invention 2Optical thin film can have the above film strength of 30MPa, especially more than the 110MPa.At this, because film strength surpasses 30MPa, even the Wiping film surface does not have scratch, MgF yet 2Optical thin film is easy to be applied on the wider purposes.
MgF 2The central wavelength lambda of the refractive index of optical thin film in design of the present invention 0Can be 1.10～1.42.At this, because MgF 2The refractive index of optical thin film is easy to form anti-reflective film as low-index material within the specific limits.
Multilayer optical film of the present invention is the multilayer optical film that a plurality of (that is, a plurality of or most) optical thin film lamination can be formed, and on outermost layer lamination MgF of the present invention 2Optical thin film.Multilayer optical film of the present invention is owing to lamination MgF of the present invention on its outermost layer 2Optical thin film, thus outermost refractive index can suppress to very low, thereby can obtain in wide wavelength coverage and extensive angle scope, having the anti-reflective film of antiradar reflectivity.
Multilayer optical film of the present invention is the multilayer optical film that a plurality of optical thin film laminations can be formed, and has multilayer MgF of the present invention 2Optical thin film.At this, because MgF 2The physical strength height of optical thin film is so but other layer of lamination (accumulation) makes MgF 2Application of optical film is wider.Multilayer optical film of the present invention can have adjacent a plurality of aforementioned MgF 2Optical thin film, the MgF that this is adjacent 2Its refringence of optical thin film is at 0.02～0.23.
Multilayer optical film of the present invention can be a plurality of optical thin film laminations and forms, and has MgF of the present invention 2Optical thin film and utilize the formed optical thin film of dry process.
Optical module of the present invention comprises: optical surface is with plane or the curved surface shape is formed, refractive index is 1.4～2.1 base material, and at least one optical surface of this base material the MgF of the present invention of lamination 2Optical thin film.
In the optical module of the present invention, it is 0.5～2 curved surface shape that the optical surface of aforementioned substrates also can form D/R (that is the radius R of the effective diameter D/ lens of lens).At this, according to optical module of the present invention, because MgF 2Optical thin film can utilize wet process to form, so even D/R is the curved surface of particular range, also can forms homogeneous thickness on optical surface is all, and be easy to obtain the good optical characteristic.
Moreover optical module of the present invention also can have substrate and at the multi-layer anti-reflective film that forms on this substrate (it is made of several different laminated layer of the refractive index more than three layers), the superiors with the side medium adjacency of multi-layer anti-reflective film are MgF of the present invention 2Optical thin film, its refractive index central wavelength lambda in design 0Be below 1.30, and the layer beyond the superiors, it is with refractive index central wavelength lambda in design 0Be layer and the refractive index central wavelength lambda in design more than 2 0Be that 1.38～1.7 laminated layer forms.At this, wavelength coverage characteristic or incident angle characteristic can significantly promote, and for the light by the incident of extensive angle scope, its refractive index can suppress very lowly, and the reflectivity in wide wavelength coverage can suppress to very low.
Moreover, optical module of the present invention, the refractive index central wavelength lambda in design of the layer that it is adjacent with aforesaid base plate 0Can be 1.38～1.7, and count, the refractive index of second layer central wavelength lambda in design by that side of medium 0Can be more than 2.By as above-mentioned method adjust refractive index, can further suppress reflectivity lower in wide wavelength coverage, can obtain reflectivity being suppressed very low optical module.
Optical system of the present invention can be Rn, m its normal-incidence reflection rate of ghost image generation face when being Rm produce its normal-incidence reflection rate of face when n ghost image in the optical system also, satisfies Rn * Rm≤0.002% (region-wide at visible region).When satisfying this and concern, can further be suppressed the picture of ghost image and dazzle with optical system.
Optical system of the present invention also can it at least simultaneously be provided with multi-layer anti-reflective film of the present invention in aforementioned n and m ghost image generation face.At this, can further be suppressed the picture of ghost image and dazzle with optical system.
Optical system of the present invention, by the aperture of optical system, aforementioned multi-layer anti-reflective film can be arranged on the face of plane or concave surface.At this,, can further be suppressed the picture of ghost image and dazzle with optical system.Also be, because aperture from optical system, if on the face of plane or concave surface, producing reflection, its influence to picture is big than the reflection that other face produced, so utilize multi-layer anti-reflective film to be set with inhibitory reflex on this face, itself and the situation comparison that is provided with on other face can be obtained can more effective inhibition ghost image and the picture of dazzle.
Optical module of the present invention can be used for the light of wavelength coverage at 400～800nm.Optical module of the present invention can be used for imaging optical system or viewing optical system.
Optical system of the present invention is made up of a plurality of optical module that is arranged between object and image planes, and at least one is optical module of the present invention for aforementioned a plurality of optical modules.
According to second form of the present invention, provide a kind of MgF 2The manufacture method of optical thin film, it has: modulation has MgF 2Particulate is dispersed in the technology of sol solution wherein, the technology of modulation bond (containing the composition that can form amorphous silicon oxide binder through reaction), the technology of aforementioned sol solution being mixed with aforementioned bond solution and modulating coating fluid, be coated on aforementioned coating fluid on the base material and carry out drying and the technology of film forming, and the Technology for Heating Processing after the film forming.
Utilize MgF of the present invention 2The manufacture method of optical thin film can be made aforementioned optical thin film of the present invention.According to this manufacture method, owing to being mixed with bond solution, sol solution modulates coating fluid, and be coated on this coating fluid on the base material and carry out drying and film forming, so can be coated on sol solution and bond solution on the base material in the lump, and reduce coating, drying and the formality of film forming, be easy to make and can obtain the MgF of effect as described above 2Optical thin film.
According to the 3rd form of the present invention, it provides a kind of MgF 2The manufacture method of optical thin film, it has: modulation MgF 2Particulate is dispersed in the technology of sol solution wherein, the technology of modulation bond (containing the composition that can form amorphous silicon oxide binder through reaction), be coated on aforementioned sol solution on the base material and carry out drying and form the technology of multiple aperture plasma membrane, the technology of aforementioned bond of coating and impregnation bond on aforementioned multiple aperture plasma membrane, and the Technology for Heating Processing after the impregnation.
According to MgF of the present invention 2The manufacture method of optical thin film, because coating sol solution and the dry multiple aperture plasma membrane that forms on base material, and on multiple aperture plasma membrane coating bond solution and impregnation bond, so do not need with sol solution and the mixed uniformly process of bond solution, and because each solution and unmixed, so the interaction between component of each solution is few, and is easy to select each composition, can obtain the MgF of effect as described above thereby be easy to make 2Optical thin film.So can select of the present invention second or the manufacture method of the 3rd form according to the solution composition kind.
MgF of the present invention 2The manufacture method of optical thin film also can synthesize MgF by magnesium compound and fluorine compounds are reacted in solvent 2Particulate and modulate aforementioned sol solution.By this, can modulate and make MgF 2Particulate is dispersed in sol solution wherein.
MgF of the present invention 2The manufacture method of optical thin film also can be by making aforementioned magnesium compound mix in solvent with fluorine compounds and pressurizeing and/or aforementioned sol solution is modulated in thermal treatment.By this, be easy to modulate the higher MgF of crystallinity 2Particulate is dispersed in sol solution wherein.
At MgF of the present invention 2In the manufacture method of optical thin film, aforementioned magnesium compound can be magnesium acetate, and aforementioned fluorine compounds can be hydrofluorite, and aforementioned solvents can be methyl alcohol.
At MgF of the present invention 2In the manufacture method of optical thin film, the two the mol ratio of magnesium that is present in fluorine in the described fluorine compounds in the aforementioned solvents and described magnesium compound can be 1.9～2.0.
At MgF of the present invention 2In the manufacture method of optical thin film, the composition that can form aforementioned amorphous silicon oxide binder can be organo-silicon compound.Because organo-silicon compound can be by reaction at MgF 2Form SiO between particulate 2So, can make MgF with a spot of bond 2Link between particulate.
At MgF of the present invention 2In the manufacture method of optical thin film, aforementioned organo-silicon compound also can be alkoxy silane or its polymkeric substance, or poly-silazane.If use these compounds, can react and make MgF with lower temperature 2Link between particulate.
At MgF of the present invention 2In the manufacture method of optical thin film, be coated on that silicon is converted into SiO in bond solution on the aforementioned multiple aperture plasma membrane or the coating fluid 2Concentration can be below the 5wt%.By this, utilize less SiO 2Can make MgF 2Link between particulate.
MgF of the present invention 2The manufacture method of optical thin film also can utilize spin-coating method or dip coating that aforementioned coating fluid or sol solution are coated on the described base material.Utilize these methods to be easy to be formed uniformly MgF 2Optical thin film.
MgF of the present invention 2The manufacture method of optical thin film also can utilize spin-coating method that aforementioned coating fluid or sol solution are coated on the described base material under the atmosphere of relative humidity 5%～40%.The inventor finds, by being coated with under specific relative humidity as above-mentioned, being difficult for producing non-uniform phenomenons such as radiation striated, and can more being formed uniformly MgF 2Optical thin film.
MgF of the present invention 2The manufacture method of optical thin film also can be after being supplied to described base material with aforementioned coating fluid or aforementioned sol solution, and making this base material in 0～3 second is that 500rpm～9000rpm is rotated with the maximum number of revolutions, and utilizes this spin-coating method to be coated with.By this, be difficult for producing non-uniform phenomenons such as radiation striated, and be easy to more be formed uniformly MgF 2Optical thin film.
MgF of the present invention 2The manufacture method of optical thin film can be by adjusting coating and the SiO that contains silicon in the bond solution that is immersed on the aforementioned multiple aperture plasma membrane or the coating fluid 2Conversion concentration is made the MgF with desired refractive index 2Optical thin film.Moreover, MgF of the present invention 2The manufacture method of optical thin film, the mol ratio of the fluorine of the fluorine compounds by adjusting aforementioned sol solution and the magnesium of magnesium compound can be made the MgF with desired refractive index 2Optical thin film.As mentioned above, by the silicon concentration of adjustment bond solution or coating fluid, or the F/Mg ratio in the adjustment sol solution, can adjust resulting MgF 2Its refractive index of optical thin film is so be easy to make the aforementioned MgF with desired refractive index 2Optical thin film.In addition, MgF 2Atomic mean grain size can be 1nm～100nm.
The MgF of the mixture of signing an undertaking of the present invention 2Sol solution, it is applicable to according to manufacture method of the present invention makes MgF 2During optical thin film, comprise alkoxy silane or its polymkeric substance and mean grain size MgF at 1nm～100nm 2Particulate.This has the MgF of bond 2Sol solution can generate SiO as long as be coated with and make it dry 2, can obtain utilizing a small amount of SiO 2Make MgF 2The MgF that particulate links 2Optical thin film.
Below, first and second examples of the present invention are described in regular turn.
First example
Fig. 1 represents the MgF that is formed with of first example 2Optical thin film (MgF 2-SiO 2Film) optical module.This optical module 100 has base material 10 and the MgF of lamination on its smooth optical surface 2Optical thin film 11.It is formation such as 1.4～2.1 glass, plastics that base material 10 utilizes refractive index, also can be sheet material or lens.The optical surface of base material 10 also can form the curved surface shape.
Optical thin film 11 is an anti-reflective film, and its lamination is subjected on the optical surface of light-struck one side at least at this base material 10, and in this example, it is the MgF of individual layer 2Anti-reflective film.
This optical thin film 11 has MgF 2Particulate 12 and amorphous silicon oxide binder 13 are at many (number) individual MgF 212 of particulates, many (number) individual MgF 2Particulate 12 utilizes amorphous silicon oxide binder 13 to be connected with 10 of base materials.In Fig. 1, bond 13 is configured to and around MgF 2Around the particulate 12.
MgF 2Particulate 12 is by MgF 2The particulate that crystallization is formed, and preferred mean grain size is the high particulate of crystallinity of 1nm～100nm.This is because the MgF high to this crystallinity 2Particulate 12 is at the MgF of majority 212 of particulates are easy to form most spaces 14, and are easy to suppress to make the compact substance structure that adhesion between ongoing particulate etc. is produced.
Amorphous silicon oxide binder 13 is (by the SiO of amorphous silica etc. by oxide 2The formed reticulate texture that is constituted) forms, and be present in most MgF that is close to or connects with irregular shape 212 of particulates or base material 10 and the MgF that is close to or connects with base material 10 212 of particulates connect to one with these materials.
With respect to MgF 2Particulate 12, though above-mentioned amorphous silicon oxide binder 13 can be any ratio, the intensity that can fully obtain film itself and with the scope of the adhesion of base material 10 in, be to serve as preferred on a small quantity with amorphous silicon oxide binder 13.With respect to MgF 2Particulate 12 is so that amorphous silicon oxide binder 13 is that 10wt%～30wt% is for preferred.Be present between particulate by aforementioned proportion, can suppress the use amount of environment resistant poor slightly amorphous silicon oxide binder 13 and make MgF 2Particulate 12 connects, and can take into account film strength and environment resistant.
To this MgF 2Optical thin film 11 is arranged on the very thin thickness of the amorphous silicon oxide binder 13 on the film surface that is subjected to light L irradiation, is arranged at the MgF on film surface 2Particulate 12 its lip-deep amorphous silicon oxide binder 13 thickness are below 5% of irradiates light L wavelength.Moreover, be present in MgF 2The MgF of 12 of particulates, majority 2The amorphous silicon oxide binder 13 that particulate 12 and base material are 10, its thickness is with than MgF 2The particle diameter of particulate 12 is thin for preferred.Based on the reason on making, the comparable MgF of thickness of these amorphous silicon oxide binder 13 parts 2The particle diameter of particulate 12 is thick.
As the MgF that is disposed at the film surface 2Atomic lip-deep amorphous silicon oxide binder 13 its thickness surpass 5% o'clock of irradiates light L wavelength, can be considered fine and close silicon dioxide film on the optics, and it is 1.42 silicon dioxide film that the superiors become refractive index; If its thickness is lower than at 5% o'clock of irradiates light L wavelength, owing to can ignore the influence of optics, the superiors can become the MgF of low-refraction 2Optical thin film.Moreover amorphous silicon oxide binder 13 thickness can measure by penetrating with the measurement of reflection beam splitting characteristic or (sweep type) electron microscope observation in film cross section.
So adjust the MgF of bond thickness 2Optical thin film 11, its refractive index can be 1.10～1.50, utilizes the measured film strength of micro-indentations method to can be more than the 30MPa, again with comparatively preferred more than the 110MPa.
Moreover, though this MgF 2Optical thin film 11 can be by being filled in most MgF with amorphous silicon oxide binder 13 212 formed majority spaces 14 of particulate promote film strength, even but do not fill amorphous silicon oxide binder 13 and still can keep most spaces 14, can reduce MgF by this 2The refractive index of optical thin film 11.
In this example, MgF 2Optical thin film 11 is porous structure, also, and at the MgF of base material 10, majority 2Particulate 12 and link its etc. amorphous silicon oxide binder 13 form most irregular spaces 14 to each other.In porous structure, voidage is serving as preferred less than 50%.If this is because the voidage height, though can reduce refractive index, the easy step-down of the physical strength of film carries out Wiping film etc. with hand and promptly peels off easily.
This MgF 2Optical thin film 11 forms on plane optical surface as can be as shown in Figure 1, also can form on curved optical surface.At this, can on being 0.5～2 curved surface, D/R (radius Rs of the effective diameter D/ lens of lens) form, especially can on being 0.5～1 curved surface, (the effective diameter D of lens)/(radius Rs of lens) form.This D/R represents the curved surface degree of lens, and 2 represent hemisphere curved surface completely, is worth more little mild more.
In the situation that curvature is little or area is big of base material 10, for the optical thin film that utilizes dry process film forming such as vacuum vapour deposition or sputtering method to form, can't form the optical thin film of uniform thickness, generally speaking, be thickness on the face of inclination, the thin thickness orthogonal thereto with the raw material supplying direction with it.Yet, because the MgF of this example 2Optical thin film 11 is to utilize wet process film forming described later, so can form uniform film thickness on optical surface.
If utilize MgF with this structure 2Optical thin film is because with MgF 2Particulate utilizes amorphous silicon oxide binder to be filled in this MgF as the main component of film 2Link between particulate, so can make MgF 2Between particulate and MgF 2Particulate 12 carries out brute force with 10 of base materials and engages, and can promote the adhesion of film strength and film and base material.Moreover, because the MgF of main component 2It is environment resistant good for particulate, and environment resistant poor slightly, by SiO 2The amorphous silicon oxide binder of being formed 13 is only at MgF 212 of particulates and MgF 2Particulate engages with 10 of base materials, so its use amount is few, and is easy to guarantee the environment resistant of film integral body.Moreover, because the use refractive index is 1.38 MgF 2Particulate can reduce the refractive index of film, and SiO 2Refractive index be lower by 1.42, so even and MgF 2Carry out compoundization, the refractive index of film can not uprise yet.
Moreover, because at MgF 2Particulate 12 (is disposed at MgF 2Optical thin film 11 surfaces) lip-deep amorphous silicon oxide binder 13 its thickness are lower than 5% of irradiates light L wavelength, so not at MgF 2Form thick-layer on the film surface of optical thin film 11 by amorphous silicon oxide binder 13 formed densifications, and can be with MgF 2The refractive index of optical thin film 11 suppresses can obtain the good optical thin films of optical characteristics such as reflectivity to very low.
Especially, because this MgF 2Optical thin film 11 is formed at the outermost layer that is subjected to light L irradiation, so by making MgF 2Optical thin film 11 refractive indexes are fallen very lowly, thereby can obtain sufficient antireflective property.
Then, utilize Fig. 2 to illustrate and be provided with these MgF 2The imaging optical system of optical thin film.This imaging optical system 118 is made up of a plurality of optical module that is arranged between object and image planes, and it is to be used for the zoom lens that camera is used.A plurality of optical modules are illustrated by object side, be provided with in regular turn: be used for the parallel flat F of cover glass, convex surface is towards the meniscus L1 of object side, the joint lens that convex surface is fitted towards the meniscus L3 of object side towards the meniscus L2 of object side and convex surface, biconcave lens L4, biconcave lens L5, the joint lens that convex surface is fitted towards the meniscus L6 of object side and biconvex lens L7, opening aperture P, the joint lens that biconvex lens L8 and biconcave lens L9 fit, the joint lens that convex surface is fitted towards the meniscus L10 of object side and biconvex lens L11, and biconvex lens L12; Form the picture of object by this at imaging surface I.
Moreover a part of in these a plurality of optical modules or all forms MgF at it on the one-sided or double-sided surface 2Optical thin film.
Moreover, for the ghost image that in imaging optical system 118, is produced on the face of the parallel flat F of close object side as side, can be by on this face, forming MgF 2Optical thin film 11 and effectively being prevented.Promptly be used in the viewing optical system that eyepiece is set in the image planes side of above-mentioned imaging optical system, MgF 2Optical thin film 11 can be played effectiveness equally, and can be observed the imaging that it has suppressed ghost image or dazzle.
In this imaging optical system, owing on the surface of at least one optical module, be provided with MgF 2Optical thin film is so lamination number that can be less is reached preferable optical properties such as reflection characteristic.
Moreover, in this example, though understand the MgF that on optical surface, forms individual layer 2The example of optical thin film, but also can form the optical thin film of multilayer at optical surface, at this, can use MgF by the one deck in multi-layer optical film 2Optical thin film.
Use above-mentioned MgF 2The low refractive index film of optical thin film, compared to the situation of using individual layer, its will utilize the formed films of dry process such as vacuum vapour deposition, sputtering method, CVD method, with above-mentioned MgF 2Optical thin film or the multilayer film that utilizes the formed film of known wet process to combine can be brought into play more good optical performance.
For example, with refractive index at the low-refraction MgF below 1.30 2Optical thin film is arranged on the multilayer optical film of the superiors, and its wavelength coverage characteristic or incident angle characteristic significantly promote, and the reflection of light rate by the incident of extensive angle institute can be suppressed to very low, and also the reflectivity of wide wavelength coverage can be suppressed to very low.At this, can suitably select formed film of known dry process or the formed film of wet process etc. for use as counterdie.If to utilize the formed MgF of wet process 2Optical thin film 11 is as counterdie, then comprise the superiors at interior holostrome all easily with uniform film thickness film forming.
Moreover, also can comprise two-layer adjacent above-mentioned MgF being subjected on light-struck optical surface to form 2The multilayer optical film of optical thin film.At this, in the superiors the low MgF of refractive index is set as far as possible 2Optical thin film 11, counterdie then are suitable for and comprise the higher MgF of refractive index 2The membrane structure of optical thin film 11.
Moreover, MgF 2Optical thin film 11 can be adjacent and lamination.At this, adjacent MgF 2Optical thin film serves as preferred with refringence 0.02～0.23, and with the MgF of inboard 2Its refractive index of optical thin film is than the MgF in the outside 2Optical thin film Gao Weijia.Identical with general anti-reflective film, can improve wavelength coverage characteristic etc. by this.Moreover, as long as inboard MgF 2Its refractive index of optical thin film is than the MgF in the outside 2Optical thin film refractive index height is because the film strength of inboard optical thin film is strong than the outside, so be easy to lamination and manufacturing.
Then explanation is about above-mentioned MgF 2The manufacture method of optical thin film.This MgF 2The manufacture method that optical thin film is a little is for the modulation sol solution (has the MgF that mean grain size is 1nm～100nm 2 Particulate 12 is dispersed in wherein) and modulate bond solution (it contains the composition that can form amorphous silicon oxide binder 13 through reaction), by these materials are provided to the optical surface of base material 10, make most MgF 2Particulate 12 is piled up, and utilizes amorphous silicon oxide binder 13 to link this MgF 212 of particulates and MgF 2Between particulate 12 and the base material 10.Sol solution (MgF 2Particulate 12 is dispersed in wherein), it makes magnesium compound mix with fluorine compounds in solvent and reacts, synthesizing M, 2 Particulate 12 is modulated.
As magnesium compound, can use acetate, chloride, alkoxide etc., preferred magnesium acetate.As fluorine compounds, can use as hydrofluoric acid aqueous solution (hydrofluorite), Anhydrous Hydrofluoric Acid, trifluoroacetic acid etc. preferred hydrofluorite.Can use organic solvents such as alcohol as solvent, particular methanol.
Moreover, when using the high solvent of evaporation rate such as methyl alcohol,, be difficult for film forming equably, so after synthesizing, preferably replace with the solvent of senior alcohols such as the lower propyl alcohol of vapor pressure, butanols etc. because the evaporation rate during film forming is fast.
For this synthetic reaction, with the MgF that in solvent, is generated 2What the particulate crystallinity was high is preferred.This is because by improving its crystallinity, even MgF 2Particulate is at MgF 2Pile up during the optical thin film film forming, also can be suppressed between particulate and adhere, can fully form pore by this, thereby can form multiple aperture plasma membrane.
In order to improve MgF 2Atomic crystallinity, preferably with magnesium compound with carry out pressurized treatments and/or thermal treatment after fluorine compounds mix.For example, if make sol solution carry out high temperature high pressure process, then MgF 2Particulate will produce crystallization and crystal grain-growth, and can form the more multiple aperture plasma membrane of high porosity,, also can form low refractive index film that is.As described later, because refractive index also uprises when the intensity of multiple aperture plasma membrane uprises, in order to obtain low-refraction and high-intensity film, preferably can obtain the low-down MgF of refractive index 2The sol solution of film is as the basis.
Moreover, when using magnesium acetate to use methyl alcohol as solvent simultaneously, preferably acetic acid and methyl alcohol are reacted form methyl acetate by carrying out high temperature high pressure process as magnesium compound.This is because if at MgF 2Contain a large amount of acetic acid in the sol solution, after sol solution concentrates, will form gel and difficult coating, can produce and to form thick MgF 2The situation of optical thin film.
The inventor finds, modulation MgF 2The magnesium mol ratio of the raw material during sol solution, the fluorine of fluorine compounds and magnesium compound (below, also claim " F/Mg ") will influence MgF 2The refractive index of optical thin film.Also promptly, even with the SiO of same concentration 2Liquid is handled MgF 2Film is to the MgF by different hydro fluoric acid/magnesium acetate ratio 2The formed MgF of sol solution 2Film, last refractive index also can be variant.
Therefore, about MgF 2The modulation of sol solution, preferred F/Mg is than with in certain scope, and more preferably 1.9～2.0.If it is low that F/Mg compared, it is fine and close that resulting film becomes easily, and refractive index easily uprises; On the other hand, if it surpasses 2.0, then in the sol solution modulated process, easily become gel.
Therefore, by suitably with this F/Mg than being adjusted in 1.9～2.0 the scope, can will make MgF 2The refractive index of optical thin film is adjusted to desired value.
At this, when F/Mg than for higher 1.99～2.00 the time, even the concentration of aftermentioned bond solution is heightened refractive index also to be difficult for uprising, so be fit to the film of making low-refraction.On the other hand, when reducing to 1.95 left and right sides as if the F/Mg ratio, even owing to use the bond solution of low concentration, refractive index also uprises, so be fit to make the film of high index of refraction.This is to compare the MgF that is synthesized because reduce F/Mg 2The particle surface destabilization, after piling up film forming, the space 14 between particulate crumbles easily, so refractive index uprises.
If by adjusting this F/Mg ratio and SiO 2Liquid concentration makes refractive index be adjusted to expectation value, is used as anti-reflective film owing to can be adjusted to best refractive index at the different various base materials of refractive index, so the anti-reflective film that manufacturability can be good.Moreover, MgF 2The MgF of sol solution 2Concentration preferably is lower than 3%.Though the concentration height can reduce refractive index, too highly will be easy to become gel.
Then, modulation bond solution (wherein having comprised the composition that can form amorphous silicon oxide binder through reaction).
The composition of amorphous silicon oxide binder can be formed through reaction, MgF can be used for promoting 2The physical strength of multiple aperture plasma membrane and with the adhesion of base material, it comprises: finally become the raw material that mesh forms oxide, or the precursor (precursor) of the state before mesh forms oxide etc.It is so-called network former that this mesh forms oxide, and preferably with SiO 2Material as major component.About bond solution, preferably utilize thermal treatment and generate SiO 2
Utilize thermal treatment and generate SiO 2Organo-silicon compound, the material of its representative is the poly-silazane of alkoxy silane and perhydrogenate for example.
Alkoxy silane is tetramethoxy-silicane for example, tetraethoxysilane, tetrapropoxysilane, four butoxy silanes, four trimethoxy silanes, methyl triethoxysilane, methyl tripropoxy silane, methyl three butoxy silanes, ethyl trimethoxy silane, ethyl triethoxysilane, ethyl tripropoxy silane, ethyl three butoxy silanes, propyl trimethoxy silicane, propyl-triethoxysilicane, propyl group tripropoxy silane, propyl group three butoxy silanes, dimethyldimethoxysil,ne, dimethyldiethoxysilane, dimethyl dipropoxy silane, dimethyl dibutoxy silane, diethyl dimethoxy silane, the diethyl diethoxy silane, diethyl dipropoxy silane, diethyl dibutoxy silane, Methylethyl dimethoxy silane, methyl-propyl diethoxy silane etc.
When using alkoxy silane,,, can reduce changing into SiO as if utilizing acid catalyst (catalyst) to add water decomposition in advance and carrying out polycondensation though can directly use 2So required heat treatment temperature is even more ideal.
About using tetraethoxysilane, and form reticulate texture, show in " science of sol-gel process, Asia are Cheng Fengshe (1989) admittedly " on the books doing flower Ji husband by adding water decomposition as alkoxy silane.In view of the above, as if ℃ following mixed liquor that stirs tetraethoxysilane, water, acid, ethanol, will produce the following formula reaction in room temperature～80.
[changing 1]
nSi(OC 2H 5) 4+4nH 2O nSi(OH) 4+4nC 2H 5OH
If had a Si (OH) with what generate 4Solution heat-treat and make it to carry out polymerization, then form SiO 2Solid.
When using poly-silazane,, divide reaction and form SiO with water in air according to following reaction equation as organo-silicon compound 2
[changing 2]
SiH 2NH+2H 2O SiO 2+NH 3+2H 2
If use the poly-silazane solution added the small amount of amine series catalysts, even also can react and make it change into SiO in room temperature 2Generally speaking, if more than 50 ℃, relative humidity heat-treats under the high humility more than 50% and makes it to change into SiO 2, owing to can obtain sufficient film strength in the short period, so even more ideal.
The inventor finds that the concentration of bond solution is to influence MgF when using this bond solution film forming 2The refractive index of optical thin film and the essential condition of physical strength.When the concentration raising of bond solution, though the film strength grow, refractive index also has the tendency that uprises.Moreover the concentration high shrinkage also uprises.Based on this, when bond solution becomes SiO through thermal treatment 2The time can produce strong convergent force.
If this bond solution concentration is too high, then connect MgF again, 2Also formed the film of bond on the multiple aperture plasma membrane.Consequently, owing on uppermost surface, formed densification and the higher SiO of refractive index 2So film is unsatisfactory for the broadbandization or the extensive angle scopeization of optical thin film.
Therefore, if the silicon concentration in this bond solution is converted into SiO 2Concentration, then preferably be lower than 5wt%, more preferably less than 2wt%.Moreover for a rubbing method described later, though the coating fluid that mixes with sol solution and bond solution is coated on the base material, even in this case, the silicon concentration of coating fluid is converted into SiO 2Concentration also preferably is lower than 5wt%, more preferably less than 2wt%.
So, can be with resulting MgF by the concentration of adjusting this bond solution 2The refractive index of optical thin film is adjusted to needed value.The concentration of bond solution is low more, resulting MgF 2Its refractive index of optical thin film is also low more, does not use the MgF of bond solution fully 2Its refractive index of optical thin film can be low to moderate 1.19.On the other hand, the concentration of bond solution is high more, and its refractive index is also high more, only with the SiO of bond solution film forming 2The refractive index height to 1.42 of film.Therefore, can be by the concentration of adjusting this bond solution with resulting MgF 2Its refractive index of optical thin film is set in 1.19～1.42.
In the method for the invention, will be supplied on the base material 10, utilize thermal treatment to make most MgF as sol solution and the bond solution that above-mentioned method adjustment forms 2Particulate is configured on the surface of base material 10, utilizes amorphous silicon oxide binder to make this MgF simultaneously 212 of particulates and MgF 210 of particulate 12 and base materials link.
At this, because resulting MgF 2Its refractive index of optical thin film and film strength etc. are relevant with concentration, so can suitably select MgF 2The usage ratio of sol solution and bond solution, film strength or uppermost surface that preferably can anti-wiping form thick SiO 2Film.
Provide the method to the optical surface formation face of base material 10 can be as described below sol solution and bond solution.
The 1st kind of method forms porous matter MgF on base material 10 2Be coated with bond solution behind the film again and make its infiltration (being called " secondary rubbing method ").The 2nd kind of method is in advance at MgF 2In the sol solution behind the hybrid junctions mixture solution, this potpourri is coated on coating process (being called " rubbing method ") on the base material 10.
Wherein, in the secondary rubbing method, sol solution can use alkoxy silane or poly-silazane; Preferred alkoxy silane in rubbing method, this be based on poly-silazane just at last trace also can't be mixed in the solvent that contains water.
Moreover, use in the situation of poly-silazane at a rubbing method, because MgF 2The solvent of sol solution is a methyl alcohol, so must be with MgF 2The solvent exchange of sol solution becomes the non-water solvent of dimethylbenzene except that alcohol, ketone, ester class or butyl oxide etc.
Again, in the situation of secondary coating, though at firm coating MgF 2Behind the sol solution, it seems that in appearance film is dry, but because solvent still remains in the space of film, and bond solution can't infiltrate fully, therefore, the MgF that secondary rubbing method coating sol solution is formed 2After the abundant drying of film, be coated with bond solution again.MgF 2Film can utilize heating or decompression to make its drying.
If at coating MgF 2Do not make the abundant drying of film of coating promptly be coated with bond solution behind the sol solution, the bond solution high with working concentration is identical, will be at MgF 2Form the bond film on the film.At this moment, still can on outermost surface, form densification and the higher bond film of refractive index, more undesirable for the broadbandization or the extensive angle scopeization of optical thin film.Therefore, in order not make the bond film at MgF 2Film forming on the film is so preferably reduce the concentration of bond solution or make MgF 2Film is fully dry.
In the rubbing method, even the concentration height of bond solution also is difficult at MgF 2Form SiO on the film 2Film.Moreover, at MgF 2Do not need drying after the film film forming, and coating process only needs once promptly efficient.
The secondary rubbing method must carry out MgF 2Sol solution and SiO 2Twice coating of liquid, it is to MgF 2Sol solution and SiO 2The situation that liquid can't mix is effective ways.Though once the coating since its coating process only once, escapable cost, it only limits to SiO 2Liquid can with MgF 2The situation that sol solution mixes.
In these rubbing methods, on base material, be coated with MgF 2Sol solution, bond solution or coating fluid can utilize spin-coating method or dip coating to carry out.When utilizing spin-coating method to be coated with, thickness uneven be radiation striated etc. and will become problem.About the thickness inequality, can pass through as mentioned above MgF 2The part of the solvent of sol solution (methyl alcohol) is replaced as higher alcohols such as propyl alcohol, butanols, amylalcohol to carry out the homogeneous coating.About the radiation striated, though said method can make it improve, find to be rotated coating under 40% the environment and can significantly to lower this phenomenon to be lower than in relative humidity, preferably be lower than under 33% the environment again for preferred.At this, so-called radiation striated, be meant by substrate center towards around radial striped, this is the feature of rotary coating.The mechanism that the radiation striated produces is: produce ripple because of friction on liquid film between liquid film in rotation on the substrate and air, it is uneven residual for forming trickle thickness.In order to reduce the generation of radiation striated, make relative with substrate to plectane rotate simultaneously and be rotated coating, can reduce friction effectively with air.Yet its shortcoming is that to plectane will become obstruction relatively, makes dripping of coating fluid become difficult, and is not suitable for a large amount of productions.
Because the present invention only reduces its relative humidity and can address this problem, and need not change spin coating process, also can not reduce production.When under low humidity, because the liquid film surface is dry rapidly, thus be difficult for producing ripple, and can suppress to generate the radiation striated.
Moreover, being rotated coating when being lower than in relative humidity under 5% the environment, its price is high and need special dehydrating unit, and cost will rise, so be higher than 5% more suitable with relative humidity.
Moreover, utilizing spin-coating method to advance shape when coating, after coating fluid or sol solution being provided to the base material, preferably at 0～3 second this base material of chien shih with maximum number of revolutions 500rpm～9000rpm rotation.By this, can suppress the uneven and radiation striated generation of thickness.
Then, as above-mentioned with MgF 2Sol solution and bond solution coat are heat-treated on the base material and after the film forming.By this thermal treatment, make to be present in MgF 2Between particulate or MgF 2Bond solution between particulate and base material generates SiO 2, can significantly promote the adhesion of the physical strength of film or itself and base material by this.
About this heat treated temperature, the alkoxy silane polymerization is become under the prerequisite of half finished product, lower temperature, get final product more than 50 ℃ approximately; If alkoxy silane itself then must be to get final product at the high temperature more than 300 ℃.
When if this heat treatment temperature is high temperature, because base material is had bad influence, so preferred employed base material is heat-treated with low temperature more, when use contains the bond solution of alkoxy silane, for example for glass baseplate, preferred 50～300 ℃, for plastic basis material, preferred 30～150 ℃.
On the other hand, in poly-silazane, severally can at room temperature change into SiO though have 2, generally speaking be to change into SiO with the thermal treatment more than 50 ℃ 2When use has the bond solution of poly-silazane, for example for glass baseplate, preferred 50～200 ℃, for plastic basis material, preferred 30～100 ℃.
Moreover, when use contains the bond solution of poly-silazane, form fine and close more SiO owing to temperature is high more 2So film is comparatively preferred.
According to above-mentioned manufacture method, can form hand erasable and refractive index and be low to moderate 1.23 MgF 2Optical thin film (MgF 2-SiO 2Film).And, for the little lens of radius-of-curvature that are difficult in the dry process formerly making, also can form the film of thickness homogeneous.Anti-reflective film be meant by ultraviolet ray to having good anti-reflection effect between near infrared range.Moreover, because the refractive index of may command film can be selected the refractive index of suitable film according to the refractive index of substrate, even also can become good anti-reflective film for monofilm.
Because the thermal treatment of film can be carried out at low temperature, glass substrate is out of question certainly, even be that plastic base and the joint lens that comprise resin bed also can form anti-reflective film, the range of application of this anti-reflective film is very wide.The precision optical instrument that can be used for projection lens, glass or the glass lens etc. of camera lens, microscopical object lens, binoculars lens, projector also can be used for display device or window-glass, the displaying window etc. of liquid crystal indicator, electric plasma display device, el display device, CRT display etc.
The embodiment of first example below is described.
[MgF 2The allotment of sol solution]
MgF 2Sol solution be with hydrofluorite and magnesium acetate be raw material and as following modulation form.The following solution of allotment respectively: the hydrofluorite methanol solution of the hydrofluoric acid dissolution with 50% in methyl alcohol, and magnesium acetate 4 hydrates are dissolved in magnesium acetate methanol solution in the methyl alcohol.Stir on one side magnesium acetate methanol solution a certain amount of hydrofluorite methanol solution that drips simultaneously and be deployed into MgF 2Sol solution.In the following embodiments, at allotment MgF 2During sol solution, make mol ratio as the hydrofluorite and the magnesium acetate of raw material (F/Mg than) at 1.90～2.0.Moreover the concentration of adjustment hydrofluorite and magnesium acetate makes MgF 2The concentration of sol solution is between 0.5～2wt%.
Though in sol solution, can directly synthesize MgF 2Particulate, owing to keep reaction is finished, so make MgF by carrying out high temperature high pressure process 2Synthetic reaction finish.Carry out MgF simultaneously 2Atomic crystallization is grown up with grain.High temperature high pressure process is with MgF 2The sol solution autoclave vessel of Teflon (registered trademark) system and airtight of packing into is carried out 140 ℃ of heating together with container.The MgF of sol solution 2Atomic mean grain size is 1nm～100nm (its mean grain size of following embodiment is 20nm).
By this high temperature high pressure process, the acetic acid of accessory substance and the methyl alcohol of solvent are reacted and the generation methyl acetate.At MgF 2Sol solution contains a large amount of acetic acid, if sol solution promptly concentrates without crossing high temperature high pressure process, will become gel and can't be coated with.Make most acetic acid become methyl acetate via high temperature high pressure process, can make sol solution be concentrated into high concentration by this in the mode that can not become gel.Its result can make being applicable to that visible light to thick between near infrared ray is
Figure C200580025066D00301
MgF 2Film.
[MgF 2The allotment of colloidal sol substitutional solution]
MgF through high temperature high pressure process 2Its dispersion medium major part of sol solution is a methyl alcohol, even this sol solution directly is coated with, also because the too fast and difficult film forming equably of velocity of evaporation of methyl alcohol.Therefore, after sol solution concentrated with rotary evaporator, utilize the lower organic solvent of vapor pressure,, make part methyl alcohol dispersion medium be replaced as this organic solvent and modulate MgF as the dilution of higher alcohols such as propyl alcohol or butanols 2The colloidal sol substitutional solution.
To this MgF 2The colloidal sol substitutional solution can suppress its velocity of evaporation, and be easy to be coated with uniform thickness.Especially, in the situation that methyl alcohol dispersion medium over half is replaced, easier coating equably under the state of homogeneous film thickness invariably.Moreover, MgF 2Even sol solution after displacement through 6 hours, its thickness of resulting film or the complete no change of refractive index, and film forming successfully.
[allotment of bond solution]
Allocate various bond solution as amorphous silicon oxide binder.As bond solution with alkoxy silane, be that tetraethoxysilane (TEOS) is dissolved in the methyl alcohol, add hydrochloric acid as catalyst, refluxed with 80 ℃, 24 hours.Moreover as other bond solution with alkoxy silane, it is for using the Mi Shifayin G-200B of department (registered trademark, the SiO of Osaka, Sumitomo Shi Meite (thigh) system 2Conversion concentration: 1.63%).
As bond solution, be to use carat perhydro of Li Ante Japan (thigh) system poly-silazane xylene solution NP110 (registered trademark, a concentration: 1wt%) with poly-silazane.
[allotment of coating fluid]
In adopting the situation of a rubbing method, as following at MgF 2Hybrid junctions mixture solution in the sol solution and allocate coating fluid.In through the sol solution after the high temperature high pressure process, add the as many as 50wt% of the bond solution with alkoxy silane, utilize rotary evaporator will concentrate after, by utilizing the lower organic solvent of vapor pressure, diluting, make part methyl alcohol dispersion medium be replaced as this organic solvent and allocate coating fluid as higher alcohols such as propyl alcohol or butanols.Its velocity of evaporation of this coating fluid is suppressed, and can be coated with by uniform thickness.Especially, in the situation that methyl alcohol dispersion medium over half is replaced, easier coating equably under the state of homogeneous film thickness invariably.
[assessment of the refractive index of film]
Utilize the U-4000 of Hitachi's system and the CARY5 of Varian system to measure its reflection of substrate of single face film forming and the situation of transmission respectively.Calculate and obtain refractive index and the thickness that wavelength is the film of 550nm by this result.
[assessment of shrinkage factor]
The shrinkage factor of film in the situation of a rubbing method, is measured the film thickness difference that is produced that has or not because of bond solution; In the situation of secondary rubbing method, measure bond and handle the film thickness difference that front and back are produced.
[assessment of anti-wiping]
Use the clock of synthon cleaning wiping cloth to spin the CK cleaning wiping cloth that (thigh) made, after wetted with methanol, carry out the substrate of film forming with wiping.Shine the scratch of observing film simultaneously with the cleaning wiping cloth wiping with spotlight behind by substrate, to assess anti-wiping.
[the adhesion method for measurement of film]
According to the micro-indentations method of testing of JIS R32555, use NEC three flourish made membrane rerum natura apparatus for evaluating (MH-4000) to measure the adhesion (film strength (MPa)) of film to substrate.With 35 ° of sample inclination, the press-in speed that makes the ruby casting die is that 1.4nm/sec measures.
[embodiment 1-5]
With MgF 2Concentration is 1%, hydrofluorite/magnesium acetate is than the mode that is 1.95, the hydrofluorite methanol solution is mixed in the magnesium acetate methanol solution allocates MgF 2Sol solution.Then, with this sol solution 140 ℃ of high temperature high pressure process of carrying out 24 hours.MgF after the processing 2MgF in the sol solution 2Particulate, its mean grain size is 20nm with the electron microscope observation measurement.After utilizing rotary evaporator that this sol solution is concentrated, methanol solvate is replaced 6～7% with the dilution of 1-propyl alcohol.MgF 2The MgF of sol solution 2Concentration is 2.5%, is rotated coating and forms porous matter MgF with 2000rpm on the quartz glass substrate of thick 3mm 2Film.
Substrate is carried out returning back to room temperature after 1 hour the drying at 70 ℃.As bond solution, stoste that can the Mi Shifayin G-200B of use department or it is diluted to 1.5 times, 2 times, 2.5 times, 3 times dilution with the 2-butanols.On dried substrate, these bond solution are rotated coating with 2000rpm respectively.The silicon concentration of the Mi Shifayin G-200B of department stoste is converted into SiO 2Be 1.63wt%, 3 times of dilutions are 0.54wt%, and 2.5 times of dilutions are 0.65wt%, and 2 times of dilutions are 0.82wt%, and 1.5 times of dilutions are 1.09wt%.At porous matter MgF 2Infiltrate SiO on the film 2160 ℃ of heating of carrying out 1 hour, form SiO behind the liquid in the gap of multiple aperture plasma membrane 2And formation MgF 2The MgF of optical thin film 2-8iO 2Film.
Measure resulting MgF respectively 2-SiO 2Its refractive index of film (SiO 2The processing front and back), shrinkage factor and film strength.Its result is as shown in table 1, and the concentration of bond solution is high more as can be known, MgF 2-SiO 2Its refractive index of film is high more, and film strength is also high more.Moreover if handle with bond solution, film all can shrink, and bond concentration is high more, and the shrinkage factor of film has high more tendency.It can be considered the bond solution that ought utilize thermal treatment will infiltrate in the multiple aperture plasma membrane and is transformed into SiO 2The time, produce strong convergent force and film is all shunk.By The above results as can be known, according to SiO 2The minute structure of the height may command film of liquid concentration also is the may command porosity, and the refractive index of may command film.
About the resulting MgF of embodiment 1-6 2-SiO 2Film when carrying out the test of anti-wiping, does not all produce scratch because of wiping on film.
[embodiment 6-8]
Except with MgF 2Concentration is 1%, hydrofluorite/magnesium acetate is than the mode that is 1.98,1.99 and 2.0, the hydrofluorite methanol solution is mixed in the magnesium acetate methanol solution allocates MgF 2Outside the sol solution, all the other are all identical with embodiment 1-5, utilize the secondary rubbing method to form MgF 2-SiO 2Film.The measurement of resulting its characteristic of film is as shown in table 1.
These results and embodiment 1 are compared, and hydrofluorite/magnesium acetate is higher than more as can be known, MgF2-SiO 2The refractive index of film has low more tendency.As can be known if desire to make MgF 2-SiO 2The refractive index of film is step-down as far as possible, then preferably makes hydrofluorite/magnesium acetate ratio near 2.0.Yet, when it surpasses 2.0, owing to sol solution promptly became gel or become gel when concentrated in the allotment stage, so this ratio preferably is lower than 2.0 as can be known.
With the porous matter MgF before the bond solution-treated 2Its refractive index of film is 1.23 in embodiment 1, is 1.20 in embodiment 7, differs 0.03.But after utilizing bond solution to handle, the refractive index of film becomes 1.34, is 1.26 that it is big that difference becomes, and is 0.08 in embodiment 7 in embodiment 1.Also promptly, even handle with the bond solution of same concentration, if reduce hydrofluorite/magnesium acetate ratio, then after utilizing the bond solution-treated, it is fine and close that film becomes easily; If improve the ratio of hydrofluorite/magnesium acetate, then film is difficult for becoming fine and close.
Embodiment 1 and 7 resulting MgF 2-SiO 2The scanning electron microscope photo in its cross section of film respectively as shown in Figure 3 and Figure 4.For the film of as shown in Figure 3 embodiment 1, because the edge clear in film cross section, so densification of film as can be known.As shown in Figure 4, for the film of embodiment 7, the edge in film cross section how concavo-convex (porous matter), unintelligible.
All visible MgF on both film surfaces 2What particle caused is concavo-convex, at MgF 2Do not form SiO on the film 2Film.Expose to this MgF 2-SiO 2Its minimum wavelength of the light of film is 190nm, at the MgF that is arranged at face (most external) 2The SiO that more than 5% of this wavelength (yet being more than the 9.5nm) do not arranged on its surface of particulate 2Be positioned at the MgF of face 2The lip-deep SiO of particulate 2Concrete thickness, its average thickness is less than 1nm.And at MgF 2The above SiO of its particle diameter is not arranged between particulate 2So as can be known only at porous matter MgF 2The a spot of SiO of the inner formation of film 2And with MgF 2Linked between particle.SiO 2Thickness utilize electron microscope observation to measure.
Moreover, about these MgF 2-SiO 2Film utilizes the mercury porosimeter to measure voidage, can confirm that they are between 15～35% (below 50%).
[embodiment 9-10]
Except be respectively 0.5%, 2% MgF with concentration 2, hydrofluorite/magnesium acetate is than being 1.99 condition allotment MgF 2Outside the sol solution, all the other are all identical with embodiment 1-5, utilize the secondary rubbing method to form MgF 2-SiO 2Film.The measurement of the characteristic of resulting film is as shown in table 1.
These results and embodiment 7 are compared, as can be known the MgF of sol solution 2Concentration is high more, with its refractive index of the film after the bond solution-treated low more tendency is arranged.As can be known, if desire to make MgF 2-SiO 2The refractive index of film is step-down as far as possible, then with MgF 2Concentration is adjusted to 2% and makes and get final product.Though the MgF of concentration 2% 2Sol solution gelation and viscosity is uprised slightly, but in case after carrying out high temperature high pressure process, gel promptly disappears and becomes the low sol solution of viscosity.If concentration is 3%, even owing to carry out high temperature high pressure process, gel can not disappear yet, so concentration is comparatively preferred to be lower than 3%.Moreover, because high temperature high pressure process once can only be handled limited volume, be more efficient method so improve the concentration of sol solution as far as possible.
Reduce to 1.23 at embodiment 8 and 10 its refractive indexes of resulting film, even and with clock spin (thigh) system synthon cleaning wiping cloth CK cleaning wiping cloth carry out wiping, film does not have scratch yet.
By the result of embodiment 1-10, can confirm hydrofluorite/magnesium acetate ratio, the concentration of bond solution, MgF 2Conditions such as concentration are very big to the refractive index influence of bond solution-treated caudacoria.
[comparative example 1-3]
With MgF 2Concentration is 1%, hydrofluorite/magnesium acetate is than the condition allotment MgF that is 1.90,1.95 and 2.0 2Sol solution.Use this sol solution, and do not handle, form porous matter MgF with the method identical with embodiment 1-5 with bond solution 2Film.The measurement of resulting its characteristic of film is as shown in table 1.
As shown in table 1, significantly reduce without its film strength of multiple aperture plasma membrane of bond solution-treated.Moreover even in the situation of not utilizing the bond solution-treated, comparative example 1 and 2 is compared down, and hydrofluorite/magnesium acetate is higher than more, and its refractive index has the tendency of reduction more.About comparative example 1～3 resulting MgF 2-SiO 2Film when carrying out the test of anti-wiping, is all wiped film because of wiping.
[comparative example 4]
Utilizing rotary evaporator will take charge of Mi Shifayin G-200B, to be concentrated into concentration be 3.73%, is rotated coating with 2000rpm on the BSC7 of thickness 10mm glass substrate.Then, this glass substrate is heat-treated with 160 ℃, on glass substrate, form SiO 2Film.
This SiO 2The refractive index of film is 1.42, because near solid density, so be dense film.The wavelength X of reflectivity minimum RMBe about 550nm, when under 70 ℃, the environment of relative humidity 80%, carrying out 20 hours environment resistant test (durable test), λ RMBe offset to 650nm.On the other hand, even embodiment 1 resulting film is carried out identical environment resistant test, its reflectivity is constant, and λ RMOnly be offset about 5nm.
As mentioned above, though be only by SiO 2Formed film densification, but because it is environment resistant poor, so be not suitable as the optical thin film of precision optical instruments such as camera or microscope.On the other hand, since embodiment 1～7 in MgF 2It is environment resistant better for the optical thin film of base substance, so can keep long optical property.Its mensuration characteristic of comparative example 4 resulting films is as shown in table 1.
Table 1
Figure C200580025066D00351
[embodiment 11-18]
In this embodiment, form MgF with a rubbing method 2-SiO 2Film.With MgF 2Concentration is 1%, hydrofluorite/magnesium acetate is than the condition that is 1.99 and 1.95, the hydrofluorite methanol solution is mixed in the magnesium acetate methanol solution allotment MgF 2Sol solution.Then, with 140 ℃ of high temperature high pressure process of this sol solution being carried out 24 hours.With the MgF of electron microscope observation measurement after processing 2MgF in the sol solution 2Particulate, its mean grain size are 20nm.
In this sol solution, when adding 10-50wt%, can mix equably as the Mi Shifayin G-200B of department of bond solution.Afterwards, utilize rotary evaporator that mixed liquor is concentrated, dilute with the 1-propyl alcohol and replace methanol solvate, allotment MgF 2(it comprises silicon concentration with SiO coating fluid 2Be scaled 2.5% bond).
Identical with embodiment 1-5, on quartz glass substrate, this coating fluid is rotated coating with 2000rpm, then heat-treat and form MgF with 160 ℃ 2-SiO 2Film.The measurement of resulting its characteristic of film is as shown in table 2.
By the result of embodiment 11-14 and embodiment 15-18, no matter hydrofluorite/magnesium acetate ratio is 1.99 or 1.95, along with the addition raising of the Mi Shifayin G-200B of department, refractive index has the tendency that uprises.Yet even be same addition, hydrofluorite/magnesium acetate is than being that its refractive index is low than 1.95 situation in 1.99 the situation.When refractive index greater than 1.23 the time, through wiping scratch is not arranged, and the good anti-wiping of tool.
As shown in these embodiment, as long as at MgF 2But hybrid junctions mixture solution in the sol solution uses rubbing method as far as possible one time, because only need carry out one time rotary coating, and can be than secondary rubbing method film forming more efficiently.Moreover, heat and can harden in about temperature more than 50 ℃ because the Mi Shifayin G-200B of department needs only, thus film strength can be promoted, and can anti-wiping.When resulting film in embodiment 12-18 carries out 10 hours thermal treatment in 50 ℃ atmosphere, its with heat-treat at 160 ℃ identical, carrying out wiping with the CK cleaning wiping cloth can scratch.Base material for lens is resin or the lens that comprise resin bed, for fear of resin distortion, must heat-treat with the temperature below 80 ℃, and these lens also can form the low-refraction optical thin film with film strength that can anti-wiping.
Table 2
Embodiment The mol ratio of the hydrofluorite/magnesium acetate of stoste The addition (wt%) of the Mi Shifayin G-200B of department The Mi Shifayin of department concentration (wt%, SiO in the coating fluid 2Convert) SiO 2Refractive index after the processing Film strength (MPa) Anti-wiping
11 1.99 10 0.41 1.20 110 Slight scratch
12 1.99 20 0.75 1.23 122 No scratch
13 1.99 30 1.03 1.26 131 No scratch
14 1.99 50 1.49 1.33 170 No scratch
15 1.95 10 0.41 1.35 180 No scratch
16 1.95 20 0.75 1.36 182 No scratch
17 1.95 30 1.03 1.38 195 No scratch
18 1.95 50 1.49 1.40 213 No scratch
[embodiment 19-29]
With concentration 1% MgF 2Condition allotment sol solution, 140 ℃ of high temperature high pressure process of carrying out 24 hours.After utilizing rotary evaporator that this sol solution is concentrated,, 67% methanol solvate is replaced with the dilution of 1-propyl alcohol.Make the MgF of sol solution 2Concentration is 2.5%, is rotated coating with 2000rpm on the quartz glass substrate of thick 3mm, forms porous matter MgF 2Film.
Substrate is carried out getting back to room temperature after 1 hour the drying at 70 ℃.On dried base plate, so that 2000rpm will (perhydro gathers silazane xylene solution NP100: concentration 1wt%) be rotated coating, heat-treat afterwards as the poly-silazane dimethylbenzene of bond solution.
In embodiment 19-25, hydrofluorite/magnesium acetate ratio is 1.99, except using 1% poly-silazane xylene solution, also uses and will gather the silazane xylene solution with dimethylbenzene and be diluted to 0.25,0.33 and 0.5% solution.
In embodiment 19-22, heat-treat condition with in atmosphere 150 ℃ carry out; In embodiment 23 and 24 70 ℃, humidity 80%; In embodiment 25 50 ℃, humidity 80%.
Poly-silazane concentration is high more, and the refractive index of film has high more tendency, the SiO of this and embodiment 1-5 2The situation of the Mi Shifayin of use department is identical in the liquid.Because embodiment 19 and 20 its film strengths are low, thus scratch promptly produced with the wiping of CK cleaning wiping cloth, when refractive index promptly can not produce scratch greater than 1.23.Though embodiment 23-25 heat-treats (humidity 80%) at 50～70 ℃ low temperature, its refractive index is carried out 150 ℃ thermal treatment height unexpectedly in atmosphere, and film is also fine and close.Also promptly, when using poly-silazane, be higher than atmospheric humidity,, also can form SiO even heat-treat at 50～70 ℃ low temperature by making heat treated humidity as bond solution 2And reinforcement porous matter MgF 2Film, making it can anti-wiping.In embodiment 26-29, making hydrofluorite/magnesium acetate ratio is 1.95, heat-treats with 150 ℃ and 70 ℃, humidity 80% in the atmosphere.As long as the concentration of poly-silazane is identical, arbitrary heat-treat condition all has identical refractive index.If hydrofluorite/magnesium acetate ratio is 1.95 o'clock, because MgF 2It is fine and close that film easily becomes, so even change heat-treat condition, also can not influence refractive index.
For being resin or the lens that comprise resin bed at base material, because if heat-treat with the high temperature more than 100 ℃, resin promptly is out of shape, so must heat-treat with the temperature that is lower than 80 ℃.Get final product owing to heat-treat with 50～70 ℃ in the method, so can not make this lens distortion get final product film forming.
Then, utilizing the high-pressure mercury light irradiation is that major component, refractive index are the resin bed that 1.5 ultraviolet hardening resin is formed with urethane acrylate and methacrylate, making it form thickness on glass substrate is 0.5mm, and then to form embodiment 23 or 25 resulting refractive indexes on this resin layer surface be 1.26 MgF 2-SiO 2Film.This resin bed is used for resin manufacture-illegal spherical lens.
Fig. 5 is illustrated on this resin bed and forms the MgF identical with embodiment 23 2-SiO 2The measurement of its spectral reflectance.Spectral reflectance is to utilize the spectral reflectance measuring machine U-4000 of Hitachi's system to measure.
When wavelength was 500nm, reflectivity can be reduced to 0.15%.Even be resin bed, film also can adhere on it tightly, thus identical when being glass with substrate, even, do not have scratch with the wiping of CK cleaning wiping cloth yet.Even be resin substrate, SiO 2Bond also can be brought into play the effect of the adhesion that promotes film.Because heat treatment temperature is low, it is 50～70 ℃, so resin bed is by peeling off on the substrate, also do not have distortion, fogging etc.
Table 3
Figure C200580025066D00381
[embodiment 30]
With MgF 2Concentration is 2%, hydrofluorite/magnesium acetate is than the condition that is 1.99, the hydrofluorite methanol solution is mixed in the magnesium acetate solution is deployed into MgF 2Sol solution.Then, 140 ℃ of high temperature high pressure process of this sol solution being carried out 24 hours.After utilizing rotary evaporator that this sol solution is concentrated,, 67% methanol solvate is replaced, make the MgF of sol solution with the dilution of 1-propyl alcohol 2Concentration is 4%, and is rotated coating formation porous matter MgF with 1000rpm on the quartz glass substrate in the environment of 24 ℃ of room temperatures, relative humidity 33%, at thick 3mm 2During film, film forming equably.Its refractive index is 1.19, and thickness is
Figure C200580025066D00391
If under relative humidity is 42% environment, be rotated coating, then will produce by substrate center towards radiation striated on every side with the same terms.
Make substrate carry out getting back to room temperature after 70 ℃, 1 hour the drying, bond solution (will take charge of Mi Shifayin G-200B with the 2-butanols and be diluted to 3 times) is rotated coating with 2000rpm.MgF after heat-treating with 150 ℃ 2-SiO 2Film, its refractive index are 1.20, and thickness is
Figure C200580025066D00392
Utilize the CK cleaning wiping cloth to carry out the assessment of wiping, film is scratch not.
Even will produce the MgF of radiation striated 2Film carries out SiO 2Handle, the radiation striated can not disappear yet.
Moreover, using when being added into coating fluid made in the sol solution as bond solution with the Mi Shifayin G-200B of department, be not have the radiation striated at 33% o'clock in relative humidity equally, but promptly produced the radiation striated at 42% o'clock.
[embodiment 31]
With MgF 2Concentration is 1%, hydrofluorite/magnesium acetate is than the process conditions that are 1.95, the hydrofluorite methanol solution is mixed in the magnesium acetate methanol solution is deployed into MgF 2Sol solution.Then, 140 ℃ of high temperature high pressure process of this sol solution being carried out 24 hours.After utilizing rotary evaporator that this sol solution is concentrated,, 67% methanol solvate is replaced with the dilution of 1-propyl alcohol.Make the MgF of sol solution 2Concentration is 3.5%, and carries out rotary coating formation porous matter MgF in the environment of 24 ℃ of room temperatures, relative humidity 33% on the quartz glass substrate at thick 3mm 2Film.
Maximum number of revolutions is made as 2000rpm,, when promptly reaching 2000rpm in one second, does not have the radiation striated and produce though will produce the radiation striated under the prerequisite of 2000rpm reaching in 5 seconds.
According to the difference of hydrofluorite/magnesium acetate ratio, even reduce relative humidity, also may not make the complete obiteration of radiation striated, at this moment utilize the maximum number of revolutions that reaches rotary coating in the short period of time that the radiation striated is disappeared.
[embodiment 32]
Optical glass substrate with refractive index n d=1.80 replaces quartz glass, is the MgF of 1.33-1.35 with resulting refractive index in embodiment 1,15 and 24 2-SiO 2The film film forming thereon.Measure the spectral reflectance of resulting substrate, the minimum of reflectivity is 0.1%.
In addition, with the MgF of embodiment 1 2-SiO 2The film film forming is on the concavees lens of refractive index n d=1.80, radius-of-curvature 20mm (D/R=1.83).These lens are one of lens of the lens combination of forming simple eye reflective camera.During film forming, the methanol solvate with 67% is replaced with the 1-propyl alcohol and is modulated into sol solution, is rotated coating with the revolution relay lens that reaches 2000rpm in a second.Control thickness by the concentration that changes sol solution, make lens (MgF 2-SiO 2The film film forming is thereon) reflectivity minimum when wavelength is 600nm.
So as can be known, be different from general vacuum vapour deposition, utilize rotary coating also can be on the little face of radius-of-curvature film forming equably.
Resulting concavees lens are incorporated in the lens combination of simple eye reflective camera, when using this camera to take a picture, when junior positions such as sunshine during in the picture corner, the ghost image color that is produced becomes blue phenomenon by orange and becomes not obvious significantly.In the lens group that constitutes simple eye reflective camera lens,, utilize this method can be formed uniformly MgF utilizing vacuum vapour deposition to be difficult on the face of even film forming 2-SiO 2Film, and can significantly reduce the generation of ghost image when using this lens to take a picture.
[embodiment 33]
Optical glass with refractive index n d=2.02 replaces quartz glass substrate, is the MgF of 1.39-1.41 with resulting refractive index in embodiment 4,5 and 18 2-SiO 2The film film forming thereon.Measure the spectral reflectance of resulting substrate, the minimum of reflectivity is 0.1%.
In addition, with the MgF of embodiment 4 2-SiO 2The film film forming is on the convex surface of refractive index n d=2.02, radius-of-curvature 3.5mm (D/R=1.90).These lens are one of lens of forming by microscopical objective system.During film forming, the methanol solvate with 67% is replaced with the 2-propyl alcohol and is modulated into sol solution, is rotated coating with the revolution relay lens that reaches 7000rpm in a second.Control thickness by the concentration that changes sol solution, make lens (MgF 2-SiO 2The film film forming is thereon) reflectivity minimum when wavelength is 550nm.Even be approximate hemispheric convex lens as can be known, still can be roughly film forming equably.
Resulting convex lens are incorporated into the part of microscopical object lens, when using with laser, the interference fringe that laser light caused in the field of view can be suppressed to minimum to the microscopic examination fluorescence of excitation source.In constituting microscopical object lens group, on the face that utilizes the difficult film forming equably of vacuum vapour deposition, utilize this method can be formed uniformly MgF 2-SiO 2Film, and when using the microscope with these lens to observe, can significantly reduce the generation of ghost image, and can obtain contrasting high picture.
[embodiment 34]
Go up forming 5 layers of anti-reflective film at DF13 optical glass (nd=1.74) (is 1.23 MgF with embodiment 8,10,12 and 21 resulting refractive indexes 2-SiO 2Film is arranged on the superiors).Also promptly, lamination utilizes the formed Al of dry process on DF13 optical glass 2O 3, MgF 2, ZrO 2Film, and utilize the formed MgF of wet process 2-SiO 2Film.
The composition of film, film build method and thickness are as shown in table 4 below.
Table 4
Component Become embrane method Thickness (nm)
The 5th layer MgF 2 Damp process 121.3
The 4th layer ZrO 2 Vacuum vapour deposition 11.1
The 3rd layer Al 2O 3 Vacuum vapour deposition 10
The 2nd layer MgF 2 Vacuum vapour deposition 28.8
The 1st layer Al 2O 3 Vacuum vapour deposition 10
Substrate DF13 optical glass
Fig. 6 is the result of reflectivity who measures the substrate of above-mentioned formation anti-reflective film.At wavelength is the visible region integral body of 400nm～800nm, and its reflectivity is all below 0.5%, as can be known its tool low-refraction in wide wavelength coverage.By this result,, can make unprecedented anti-reflective film according to the present invention.
[embodiment 35]
(first tunic is that embodiment is 1,3 and 17 obtained, the MgF of refractive index 1.38 go up to form 2 layers of anti-reflective film at BSC7 optical glass (nd=1.52) 2-SiO 2Film, second tunic are that embodiment is 8,10,12 and 21 obtained, the MgF of refractive index 1.23 2-SiO 2Film).Because the two-layer wet type that is becomes embrane method, so even be the little lens of radius-of-curvature, also can form uniform multi-layer anti-reflective film.
The composition of film, film build method and thickness are as shown in table 5 below.
Table 5
Component Become embrane method Thickness (nm)
The 2nd layer MgF 2-SiO 2Film Damp process 104.6
The 1st layer MgF 2-SiO 2Film Damp process 93.3
Substrate BSC7 optical glass
Fig. 7 is the result of reflectivity who measures the substrate of above-mentioned formation anti-reflective film.Because adjacent MgF 2-SiO 2Its refringence of film is 0.02～0.23, thus wavelength be whole its reflectivity of wavelength coverage of 350nm～1100nm all below 1%, it is at ultraviolet ray tool low-refraction to the near infrared broadband as can be known.By this result,, can make unprecedented anti-reflective film according to the present invention.
[second example]
Fig. 8 represents the structure of the optical module 110 of second example.
In Fig. 8, optical module 110 has multi-layer anti-reflective film 112 (comprising the different layer of refractive index more than 3 layers) on the flat optical face of substrate 111.Specifically, substrate 111 is to be formed by glass, plastics etc., can be the form of sheet material or lens.Optical surface also can be curved surface.
In this multi-layer anti-reflective film 112, the superiors' 113 refractive indexes that are positioned at side medium are set at central wavelength lambda in design 0Be below 1.30, the layer 114 beyond the superiors is by refractive index central wavelength lambda in design 0Be set at layer more than 2, with refractive index central wavelength lambda in design 0Be that 1.38～1.7 layer institute lamination forms.
Moreover in this multi-layer anti-reflective film 112, layer 115 the refractive index that is positioned at substrate 111 sides is set at central wavelength lambda in design 0Be 1.38～1.7, and by that side number of medium, the 2nd layer 116 refractive index is set at central wavelength lambda in design 0Be more than 2.
Each film of this multi-layer anti-reflective film 112 availablely is selected from that arbitrary method is carried out to film in dry processes such as vacuum vapour deposition, sputtering method, ion plating and CVD method and the sol-gel wet process such as (sol-gel).The formation method of these layers can different, also can be identical.
The material of the substrate 111 of optical module 110 of the present invention so long as optical element get final product, be not particularly limited, preferably can be applicable to optical modules such as lens, prism, filter, these optical modules 110 can promote its optical property of optical system that possesses these optical modules, and further promote the optical devices performance with this optical system.
This optical module 110 can be assembled with arbitrary optical module L1～L12 of the imaging optical system 118 that describes with Fig. 2 in first example.That is form multi-layer anti-reflective film 112 on its one-sided or both side surface of part or all that, can be in these a plurality of optical module L1～L12.At this, by the opening aperture P of optical system, it is arranged on anti-reflective film 112 on surperficial X, the Y of plane or concave surface.
Moreover, in this imaging optical system 118, be Rn when n ghost image in optical system produces its normal-incidence reflection rate of face, when m its normal-incidence reflection rate of ghost image generation face is Rm, in visible region is region-wide, can satisfy Rn * Rm≤0.002%.In addition, in n and m ghost image generation face, formation multi-layer anti-reflective film 112 on a surface at least.This imaging optical system 118 is applicable in the wavelength coverage of 400nm～700nm.
For above-mentioned imaging optical system 118,, and the superiors' 113 refractive indexes of side medium are set in design central wavelength lambda because multi-layer anti-reflective film 112 forms by the different laminated layer of refractive index more than 3 layers 0Be below 1.30, the layer 114 beyond the superiors is by refractive index central wavelength lambda in design simultaneously 0Be more than 2 layer, with refractive index central wavelength lambda in design 0Be that 1.38～1.7 layer institute lamination forms,, can suppress its reflectivity of light, can reflectivity be suppressed to very low in wide wavelength coverage simultaneously by the incident of extensive angle scope so can significantly promote the characteristic of wavelength coverage characteristic or incident angle.
Moreover, because the refractive index central wavelength lambda in design of the layer 115 of substrate 111 sides 0Be 1.38～1.7, and by that side number of medium, the 2nd layer 116 refractive index central wavelength lambda in design 0Be more than 2, so can suppress reflectivity lower.
And, owing to being arranged on, this multi-layer anti-reflective film 112 constitutes optical module 110 on the substrate 111, so this optical module 110 can suppress the reflection of light rate by the incident of extensive angle scope, and can reflectivity be suppressed to very low in wide wavelength coverage.
In addition, substrate 111 is a planopaallel plate not only, even it has curved surface, also can suppress the reflection of light rate by the incident of extensive angle scope, and can reflectivity be suppressed to very low in wide wavelength coverage.At this, for the parallel flat F of the most close object side of imaging optical system 118 as the ghost image that is produced on the side, can prevent effectively by on this face, forming multi-layer anti-reflective film 112, owing to be provided with multi-layer anti-reflective film 112 producing on the face of ghost image, so can reach better optical properties such as reflection characteristic with the configuration quantity of still less multi-layer anti-reflective film 112.
Moreover, because optical module (it is provided with multi-layer anti-reflective film 112 of the present invention) 110 can suppress reflectivity to very low, by in the optical module L1～L12 of imaging optical system 118 at least one adopt optical module 110, this imaging optical system 118 can generate the picture that reduces ghost image and dazzle.
Be Rn when n ghost image in optical system produces its normal-incidence reflection rate of face, when m its normal-incidence reflection rate of ghost image generation face is Rm, owing to can satisfy Rn * Rm≤0.002% in visible region is region-wide, imaging optical system 118 can generate the picture that reduces ghost image and dazzle more.
Because in aforementioned n and m ghost image generation face, formation multi-layer anti-reflective film 112 on a surface at least is so imaging optical system 118 can generate the picture that reduces ghost image and dazzle more.
When being Rn * Rm with m its normal-incidence reflection rate of ghost image generation face Rn, Rm at visible region at aforementioned n〉0.002% the time, obviously generate ghost image and dazzle, and reduced the quality of resulting picture.
By the opening aperture P of optical system and since multi-layer anti-reflective film 112 its be arranged on the surface of plane or concave surface, so, can more effectively obtain reducing the picture of ghost image and dazzle for optical system.Also be, if opening aperture P by optical system, when on the surface of plane or concave surface, forming reflex time, compared to the situation that on other face, forms reflection, its influence to picture is bigger, so inhibitory reflex compared to being arranged on other face, can more effectively obtain reducing the picture of ghost image and dazzle by on this face multi-layer anti-reflective film 112 being set.
Moreover as the optical system that is used for 400nm～700nm wavelength coverage, it is lower that reflectivity is reduced to.In addition, as the viewing optical system that eyepiece is set in the imaging surface side of above-mentioned imaging optical system 118, multi-layer anti-reflective film 112 also can be brought into play same effect, thereby can be observed the blur-free imaging that reduces ghost image and dazzle.
Below, the embodiment of second example is described.
[embodiment 36]
As shown in Figure 9, the film of present embodiment 36 is broadband multi-layer anti-reflective films 112 of realizing that in the visible region is region-wide 5 layers of structure of antiradar reflectivity are formed, and its composition is as shown in table 6.
Table 6
Material Refractive index Blooming
Medium Air
The 5th layer SiO 2+MgF 2 1.26 0.269λ 0
The 4th layer ZrO 2+TiO 2 2.12 0.043λ 0
The 3rd layer Al 2O 3 1.65 0.217λ 0
The 2nd layer ZrO 2+TiO 2 2.12 0.066λ 0
The 1st layer Al 2O 3 1.65 0.290λ 0
Substrate BK7 1.52
At this, with wavelength 550nm as the design on central wavelength lambda 0, its medium is an air.Substrate 111 is at λ 0Refractive index be 1.52 borosilicic acid crown optical glass (BK7), lamination structure adopts the design that is suitable for substrate 111 most.That is, this multi-layer anti-reflective film 112 is formed by 5 layers, with this substrate 111 immediate the 1st layer 121 (layers 15 of substrate 11 sides) be by aluminium oxide (Al 2O 3) form, its refractive index is 1.65 (refractive index is at 1.38～1.7), blooming is 0.290 λ 0
The 2nd layer of 122 mixolimnion (ZrO by zirconia and titanium dioxide 2+ TiO 2) form, its refractive index is 2.12 (refractive index is greater than 2), blooming is 0.066 λ 0
The 3rd layer 123 by aluminium oxide (Al 2O 3) form, its refractive index is 1.65 (refractive index is at 1.38～1.7), blooming is 0.217 λ 0
The 4th layer 124 (by that side number of medium, the 2nd layer 16) is by the mixolimnion (ZrO of zirconia and titanium dioxide 2+ TiO 2) form, its refractive index is 2.12 (refractive index is greater than 2), blooming is 0.043 λ 0
The 5th layer 125 (the superiors 13 of side medium) are by the mixolimnion (SiO of silicon dioxide and magnesium fluoride 2+ MgF 2) form, its refractive index is 1.26 (refractive index is less than 1.30), blooming is 0.269 λ 0
As mentioned above, the 1st, 3 layer 121,123 is intermediate-index layer (refractive index is at 1.38～1.7); 2nd, 4 layer 122,124 is high refractive index layer (refractive index is greater than 2); The 5th layer 125 is low-index layer (refractive index is less than 1.30).
Its spectral reflectance characteristic when vertical incidence of the multi-layer anti-reflective film of said structure as shown in figure 10, wavelength can suppress to below 0.2% at region-wide its reflectivity of 420～720nm as can be known.Moreover, incident angle be 30 degree, the branch reflective character of 45 degree, 60 when spending as shown in figure 11.Again, the branch reflective character of second example is to utilize the spectral reflectance measuring machine U-4000 of Hitachi's system to measure.
[comparative example 5]
As the comparative example of embodiment 36, that adopts same media and substrate utilizes the formed multilayer broadband of prior art anti-reflective film, and its structure is as shown in table 7.
Table 7
Material Refractive index Blooming
Medium Air
The 7th layer MgF 2 1.39 0.243λ 0
The 6th layer ZrO 2+TiO 2 2.12 0.119λ 0
The 5th layer Al 2O 3 1.65 0.057λ 0
The 4th layer ZrO 2+TiO 2 2.12 0.220λ 0
The 3rd layer Al 2O 3 1.65 0.064λ 0
The 2nd layer ZrO 2+TiO 2 2.12 0.057λ 0
The 1st layer Al 2O 3 1.65 0.193λ 0
Substrate BK7 1.52
Its spectral reflectance characteristic when vertical incidence of this multi-layer anti-reflective film as shown in figure 12, again, similarly, the angle that is incident to multi-layer anti-reflective film be 30 degree, the branch reflective character of 45 degree, 60 when spending as shown in figure 13.
Comparative example 5 is compared with embodiment 36, and in the reflectivity of the reflectance coating of embodiment 36, the normal-incidence reflection rate has part to reduce compared with the prior art more than 1/2nd, also has a splendid antireflecting performance region-wide.Again, when incident angle becomes big, compare with the reflectance coating of prior art, it has the antireflective property of reflectivity far below prior art as can be known.
[embodiment 37]
This embodiment is as shown in table 8, and multi-layer anti-reflective film 112 is made up of 7 layers of institute, and this multi-layer anti-reflective film 112 is applicable to the different a plurality of substrates 111 of refractive index simultaneously.
Table 8
Material Refractive index Blooming Blooming Blooming Blooming
Medium Air 1
The 7th layer SiO 2+MgF 2 1.26 0.275λ 0 0.268λ 0 0.271λ 0 0.269λ 0
The 6th layer ZrO 2+TiO 2 2.12 0.045λ 0 0.057λ 0 0.054λ 0 0.059λ 0
The 5th layer Al 2O 3 1.65 0.212λ 0 0.171λ 0 0.178λ 0 0.162λ 0
The 4th layer ZrO 2+TiO 2 2.12 0.077λ 0 0.127λ 0 0.13λ 0 0.158λ 0
The 3rd layer Al 2O 3 1.65 0.288λ 0 0.122λ 0 0.107λ 0 0.08λ 0
The 2nd layer ZrO 2+TiO 2 2.12 0 0.059λ 0 0.075λ 0 0.105λ 0
The 1st layer Al 2O 3 1.65 0 0.257λ 0 0.03λ 0 0.03λ 0
The refractive index of substrate 1.46 1.62 1.74 1.85
Corresponding diagram Fig. 8 Fig. 9 Figure 10 Figure 11
That is, the refractive index of substrate bundle 1 designs with 1.46,1.62,1.74,1.85 four kinds of refractive indexes when wavelength is 550nm.Each design load as shown in Figure 8.
Moreover Figure 14 represents that refractive index is substrate 1 its spectral reflectance characteristic of 1.46; Figure 15 represents that refractive index is substrate 111 its spectral reflectance characteristics of 1.62; Figure 16 represents that refractive index is its spectral reflectance characteristic of substrate 1 youngster of 1.74; Figure 17 represents that refractive index is substrate 1 its spectral reflectance characteristic of 1.85.According to these accompanying drawings as can be known, in the about 420～about 720nm of wavelength region-wide, reflectivity can suppress to below 0.2%.
As mentioned above,, also can make the thickness optimization of each layer, under the prerequisite of not destroying essential structure, obtain good broadband antireflective properties by this to add up to 5～7 layers even in the different situation of the refractive index of substrate 111.
As the multi-layer anti-reflective film 112 of above-mentioned embodiment 36 and 37, its incident light to visible region has antiradar reflectivity characteristic and extensive angle characteristic.
MgF of the present invention 2Optical thin film, (400nm～800nm) can realize the antiradar reflectivity of extensive angle scope, and has this MgF by use in the visible region 2The optical system of the optical module of optical thin film can provide that ghost image and dazzle are few, the optical system of high optical property.
In addition, by in the structure of multi-layer anti-reflective film, importing ultralow index layer, and make configuration and other layer optimization of this ultralow index layer, can obtain that the multi-layer anti-reflective film of prior art can't be realized, have a splendid performance multi-layer anti-reflective film.Therefore, optical module of the present invention and optical system not only can be applicable to need optical instruments such as high-resolution camera, microscope, binoculars, exposure device, more can be widely used in display or glass pane, the display case etc. of liquid crystal indicator, plasma display panel etc.

Claims (40)

1. MgF 2Optical thin film is characterized in that having:
MgF 2Particulate, and
Be present in this MgF 2Amorphous silicon oxide binder between particulate;
Wherein, at this MgF 2Utilize amorphous silicon oxide binder to link between particulate, and be present in MgF 2The outermost MgF of particulate 2The lip-deep amorphous silicon oxide binder thickness of particulate is below 5% of institute's irradiates light wavelength.
2. MgF as claimed in claim 1 2Optical thin film wherein, is present in adjacent this MgF 2Amorphous silicon oxide binder thickness between particulate is than this MgF 2Atomic particle diameter is little.
3. MgF as claimed in claim 1 2Optical thin film, wherein, this MgF 2Atomic mean grain size is 1nm～100nm.
4. MgF as claimed in claim 1 2Optical thin film, wherein, this MgF 2Optical thin film has porous structure.
5. MgF as claimed in claim 4 2Optical thin film, wherein, the voidage of this porous structure is below 50%.
6. MgF as claimed in claim 1 2Optical thin film, wherein, this MgF 2Have the space between particulate, and in this space, be filled with amorphous silicon oxide binder.
7. MgF as claimed in claim 1 2Optical thin film, wherein, this amorphous silicon oxide binder is formed by amorphous silica.
8. MgF as claimed in claim 1 2Optical thin film, wherein, this optical thin film intensity of utilizing the measurement of micro-indentations method of testing is for more than the 30MPa.
9. MgF as claimed in claim 1 2Optical thin film, wherein, this MgF 2The refractive index of optical thin film is 1.10～1.41.
10. a multilayer optical film is formed by a plurality of optical thin film laminations, it is characterized by the described MgF of lamination claim 1 on outermost layer 2Optical thin film.
11. a multilayer optical film is formed by a plurality of optical thin film laminations, it is characterized in that, has the described MgF of a plurality of claims 1 2Optical thin film.
12. as claim 10 or 11 described multilayer optical films, it has adjacent a plurality of MgF 2Optical thin film, the MgF that this is adjacent 2The refringence of optical thin film is 0.02～0.23.
13. a multilayer optical film is formed by a plurality of optical thin film laminations, it is characterized in that, has the described MgF of claim 1 2Optical thin film and utilize the formed optical thin film of dry process.
14. an optical module is characterized in that comprising:
Optical surface is by plane or the curved surface shape is formed, refractive index is 1.4～2.1 base material, and
The described MgF of claim 1 of lamination at least one optical surface of this base material 2Optical thin film.
15. optical module as claimed in claim 14, wherein, the effective diameter D that the optical surface of this base material has lens and the ratio of the radius R of lens are 0.5～2 curved surface shape.
16. optical module as claimed in claim 14 is applicable to the light of wavelength coverage 400nm～800nm.
17. an optical module is characterized in that having substrate, and the multi-layer anti-reflective film that forms on this substrate, this multi-layer anti-reflective film is formed by the different layer institute lamination of the refractive index more than three layers;
In this multi-layer anti-reflective film, the superiors of side medium are the described MgF of claim 1 2Optical thin film, its refractive index central wavelength lambda in design 0Be below 1.30; And the layer beyond the superiors is by refractive index central wavelength lambda in design 0Be layer and the refractive index central wavelength lambda in design more than 2 0Be that 1.38～1.7 layer institute lamination forms.
18. optical module as claimed in claim 17, wherein, layer its refractive index in design the central wavelength lambda adjacent with this substrate 0Be 1.38～1.7, and by medium one side counting, the refractive index of second layer central wavelength lambda in design 0Be more than 2.
19. an optical system is characterized in that, has a plurality of optical modules that are arranged between object and image planes, at least one is the described optical module of claim 17 in these a plurality of optical modules.
20. an optical system is characterized in that, has a plurality of optical modules that are arranged between object and image planes, at least one is the described optical module of claim 14 in these a plurality of optical modules.
21. optical system as claimed in claim 19, wherein, when n ghost image in the optical system produces its normal-incidence reflection rate of face is Rn, m its normal-incidence reflection rate of ghost image generation face when being Rm, satisfies Rn * Rm≤0.002% in that visible region is region-wide.
22. optical system as claimed in claim 20, wherein, when n ghost image in the optical system produces its normal-incidence reflection rate of face is Rn, m its normal-incidence reflection rate of ghost image generation face when being Rm, satisfies Rn * Rm≤0.002% in that visible region is region-wide.
23. optical system as claimed in claim 21 wherein, at least simultaneously is provided with this multi-layer anti-reflective film in this n and m ghost image generation face.
24. optical system as claimed in claim 21, wherein, by the aperture of optical system, this multi-layer anti-reflective film is arranged on the face of plane or concave surface.
25. as claim 19 or 20 described optical systems, it is imaging optical system or viewing optical system.
26. MgF 2The manufacture method of optical thin film is characterized in that comprising:
Modulation has MgF 2Particulate is dispersed in the technology of sol solution wherein,
Modulate and contain the technology that can form the bond of amorphous silicon oxide binder through reaction in its composition,
The technology of this sol solution being mixed with this bond solution and modulating coating fluid,
Be coated on this coating fluid on the base material and carry out drying and the technology of film forming, and
Heat-treating process after the film forming;
Wherein, at this MgF 2Utilize amorphous silicon oxide binder to link between particulate, and be present in MgF 2The outermost MgF of particulate 2The lip-deep amorphous silicon oxide binder thickness of particulate is below 5% of institute's irradiates light wavelength.
27. MgF 2The manufacture method of optical thin film is characterized in that comprising:
Modulation has MgF 2Particulate is dispersed in the technology of sol solution wherein,
Contain the technology that can form the bond of amorphous silicon oxide binder through reaction in the modulation composition,
Be coated on this sol solution on the base material and carry out the dry technology that forms multiple aperture plasma membrane,
The technology of this bond of coating and impregnation bond on this multiple aperture plasma membrane, and
Heat-treating process after the impregnation;
Wherein, at this MgF 2Utilize amorphous silicon oxide binder to link between particulate, and be present in MgF 2The outermost MgF of particulate 2The lip-deep amorphous silicon oxide binder thickness of particulate is below 5% of institute's irradiates light wavelength.
28. as claim 26 or 27 described MgF 2The manufacture method of optical thin film, comprising, magnesium compound and fluorine compounds are reacted in solvent and synthetic MgF 2Particulate is to be modulated into this sol solution.
29. MgF as claimed in claim 28 2The manufacture method of optical thin film wherein, is mixed with fluorine compounds this magnesium compound and is pressurizeed and/or thermal treatment, and is modulated into this sol solution in solvent.
30. MgF as claimed in claim 28 2The manufacture method of optical thin film, wherein, this magnesium compound is a magnesium acetate, and these fluorine compounds are hydrofluorite, and this solvent is a methyl alcohol.
31. MgF as claimed in claim 29 2The manufacture method of optical thin film, wherein, the mol ratio that is present in the magnesium of fluorine in these fluorine compounds in this solvent and this magnesium compound is 1.9～2.0.
32. as claim 26 or 27 described MgF 2The manufacture method of optical thin film, wherein, the composition that can form this amorphous silicon oxide binder is organo-silicon compound.
33. MgF as claimed in claim 32 2The manufacture method of optical thin film, wherein, these organo-silicon compound are alkoxy silane or its polymkeric substance or poly-silazane.
34. as claim 26 or 27 described MgF 2The manufacture method of optical thin film wherein, is coated on that silicon is converted into SiO in this bond solution on this multiple aperture plasma membrane or this coating fluid 2Concentration is below the 5wt%.
35. as claim 26 or 27 described MgF 2The manufacture method of optical thin film, it utilizes spin-coating method or dip coating that this coating fluid or this sol solution are coated on this base material.
36. as claim 26 or 27 described MgF 2The manufacture method of optical thin film wherein, is utilizing spin-coating method that this coating fluid or this sol solution are coated on this base material under the atmosphere of relative humidity 5%～40%.
37. as claim 26 or 27 described MgF 2The manufacture method of optical thin film wherein, after this coating fluid or this sol solution are supplied to this base material, made this base material with maximum number of revolutions 500rpm～9000rpm rotation in 3 seconds, and utilizes spin-coating method to be coated with.
38. as claim 26 or 27 described MgF 2The manufacture method of optical thin film, wherein, by adjusting coating and the SiO that contains silicon in this bond solution of being immersed on this multiple aperture plasma membrane or this coating fluid 2Conversion concentration is made this MgF with desired refractive index 2Optical thin film.
39. MgF as claimed in claim 28 2The manufacture method of optical thin film, wherein, the mole of the fluorine of these fluorine compounds by adjusting this sol solution and the magnesium of this magnesium compound is recently made a plurality of MgF with desired refractive index 2Optical thin film.
40. as claim 26 or 27 described MgF 2The manufacture method of optical thin film, wherein, MgF 2Atomic mean grain size is 1nm～100nm.
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