CA1325250C

CA1325250C - Handpiece and related apparatus for laser surgery and dentistry

Info

Publication number: CA1325250C
Application number: CA000600130A
Authority: CA
Inventors: John Taboada; Robert H. Poirier
Original assignee: REFRACTIVE LASER RESEARCH & DEVELOPMENT PROGRAM, LTD.
Current assignee: Refractive Laser Research & Development Program Ltd; REFRACTIVE LASER RESEARCH AND DEVELOPMENT Inc
Priority date: 1988-05-19
Filing date: 1989-05-18
Publication date: 1993-12-14
Anticipated expiration: 2010-12-14
Also published as: IL90318A0; IL90318A; EP0414791A1; WO1989011260A1; JPH04501963A

Abstract

ABSTRACT OF THE DISCLOSURE
Apparatus is provided for effecting medical or dental surgery, and to a related method. The subject body on which surgery is to be performed has a reference thereon or therein identified, such as a layer in the cornea, or a surface of a tooth. A
handpiece has a longitudinally extending first optical path and a second, transverse optical path, with a dichroic reflector at the juncture of the paths. The handpiece contains a variable focus lens and a fiberoptic bundle is connected axially to the distal end of the handpiece. Light is passed through the fiberoptic bundle into the handpiece, to illuminate the site. The image of the site is passed through the variable focus lens and to the fiberoptic bundle, and thence to a control apparatus for adjusting the variable focus lens so as to provide for focussing of the treatment laser beam at a predetermined distance from the reference. A laser beam is passed to the handpiece by way of the second optical path, and thence through the variable focus lens, which focuses the beam to a localized spot which is at a predetermined distance from the reference: the distance may be zero, where, for instance, the reference is the surface of a tooth which is to be ablated. The handpiece is supported by an articulating arm system which provides six degrees of freedom of motion.
A method of performing surgery comprising determining by focus condition measuring equipment the distance of a reference in a subject body, adjusting a variable focus lens by control signals proportional to the focus condition measured, and passing a laser beam through the variable focus lens in the adjusted position.

Description

132~2~0 HANDPIECE AND RELATED APPARATUS
FOR LASER SURGERY AND DENTISTRY

This invention relates to a handpiece and related apparatus for performing surgery and dentistry with a laser.
Applications of laser technology to medicine and dentistry have been suggested for well over a decade.
Advances have been rapid, and laser devices are now commonly found, not only in operating rooms, but in the offices of physicians. Among the more widely used applications of laser technology in medicine is in the field of eye surgery.
Among the uses of lasers in the medical field are ,.J

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132~2~0 cutting, cauterizing, meltlng and ablating ti~sue. It has been recognized that to effect tissue, or other materlal to the greatest degree, one or more condltlons must be met, lncluding (a) the delivery of the laser energy ln high powered pulses or wlth high continuous power: (b) the laser must be tuned to the extreme violet end of the spectrum where the photon absorption is high in organic substance, or (c) the laser must be tuned to the extreme infrared end of the spectrum where absorptlon of radlatlon by water, a maJor constltuent of llvlng tissue, 18 a factor. As ls known, condltion (a) functlons through non-linear optical processes such as dleleatric brea~down, whlch creates a flnely locallzed absorption slte because the resulting plasma ls usually opaque to the laser beam. These noted condltlon~ are extreme condltlons and have resulted ln the inabillty of some or all optlcal components to handle this extreme laser energy delivered.
In the care and treatment of eyes, it has been recognlzed that in some cases an eye may depart from a normal or "perfect" conflguration, particularly in that the outer surace of the eye, the cornea, is not curved properly, but has some excessive steepness which cause ~erataconus or myopia, resulting in impaired vislon.
Proposals have been made to correct this imperfection by changlng the lnternal structure of the stroma layer of the cornea by the application of heat and/or radlo ;:

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~32~2~0 frequency energy, but these proposals have had signlflcant deflclenales. For example, Doss et al U.S.
Patent 4,326,529 attempts to achleve the correction of corneal irregularitles by keratoplasty technlque, ln which the central stroma 18 heated with a radio frequency electrode probe, to break collagen crossllnks, to contract the collagen which i~ a part of the clear corneal medium. The method dlsclosed ln Doss et al has the dlsadvantage that the heat deposltion is not easlly locallzed in the three-dlmensional space of the cornea.
Roussell et al U.S. Patent 4,409,979 provldes apparatus for treatlng the human eye wlth laser radiatlon, and for vlewlng the slte. Reflectors and prisms are provlded to conduct light from a light source to the site, passing eccentric to the optlcal path; an image 18 conducted from the ~ite to a vlewing lnstrument, such as a mlcroscope, centrally of the optlcal path. A beam from a laser ls caused to strike the central part of a mlrror which is movable between an operatlve posltlon and a retracted posltlon. In the operatlve positlon, the mlrror dlrects the laser radlatlon to the slte, generally along the optlcal path. In the retracted posltlon, the mlrror 18 removed from the optlcal path, permlttlng passage of the aforementloned llght beam and observlng beam. A weak laser ls also provlded, whose beam passes ln a path . , .

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~32~2~0 eccentric to the optlcal path. A manually adJustable focus~ing lens i8 provlded ln the light paths to focus the light from the llght ~ource and the laser radiatlon. The arrangement pre~ents a problem whlch requlres the provlslon of a rotatable tube for houslng beam splltters and reflectors which are part of the optical path of the llght source beam, the observlng beam, and the weak laser beam. Hence, manipulatlon of the rotatable tube and manual ad~ustment of the focussing lens are required to achieve the desired viewlng and focussing, prior to the energization of the power laser and the moving of the mirror into operative position to dlrect the power laser beam to the site.
The method o~ Roussell et al has the dlsadvantage that lt cannot be moved wlth the freedom of a handplece wlth slx degrees of freedom. In addltlon, the method regulres the lnterventlon of an operator to establlsh the focal slte of the laser energy delivery.
Muckerhide U.S. Patent 4,316,467 discloses the use of a laser for treating birthmarks or lesions on the skin, in which control of the power or energy level of a laser is effected by receiving radiation reflected from the lesion by a fiberoptic bundle: a control circult senses the intensity corresponding to the color 2S intenslty of the reglon to which the laser beam is directed and varles the energy of the laser.
Goldenberg U.S. Patent 4,641,912 dlscloses an .,~',': , . .
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132~2~0 exclmer laser system used for angioplasty, and lncludes a pair of optical fibsrs, one for obtalnlng an image of the atherosclerotic plaque to be ablated by the laser energy, a second optlcal fiber being provided for laslng the plaque. A video camera and monitor are utilized to acquire and dlsplay an image of the plaque.

Karlin et al U.S. Patent 4,583,539 di~closes a system for performing surgery on the eye using a C02 laser source and an articulated arm structure, the laser energy being delivered through a probe which ls connected to the articulated arm structure and which is insertable into an eye.
Kimura U.S. Patent 4,266,549 discloses a laser scalpel including a probe through which light may be directed to illuminate the optical site: where a tumor is to be subJected to lasing, a picture or graphlc representation may be obtained. An adaptor is provided at the tip of the probe to engage the tissue at or adJacent the tumor, to establlsh the di~tance of the focusslng lens of the probe to the tumor to be laser.
Remy et al U.S. Patent 4,289,378 discloses an apparatus for ad~usting the focal point of a working laser beam onto a microscopic target region of a transparent biological ob~ect. Use is made of an auxiliary laser beam having a wavelength within the visible range, and through ~olnt manual focussing of . :. :. .. : ~:
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132~230 the laser beams, the locatlon of focussing of the worklng beam at a particular locus at a de~lred depth within the transparsnt biologlcal speclmen 18 achleved.

The aforementloned disclosures, however, lack provi~ion for a dlrect contact plano convex lens for the dellvery uf the laser energy to locl at very small ranges from the surfaces. They also lack provlsion for a contact lens surface to cover the cornea whlle the adJacent lower tissue is being lrradlated and also to serve as a gulde surface for hand held instruments.
These llmltatlons are overcome by the present lnventlon as wlll be made evldent below.
Among the patents discloslng a dental handplece for dlrectlng laser energy to a tooth ls Ota et al U.S.
Patent 4,503,853. In thls patent, the handplece lnclude~ a centrally located optlcal fiber through whlch the laser beam ls passed to the tooth. The handplece is provlded at its distal end with a dlstance spacer to engage the tooth and provlde a flxed spaclng between the tooth and the end of the optlcal flber to regulate the amount and strength of lrradlatlon of laser beams from the laser source. Myers et al U.S.
Patent 4,521,194 discloses a method of removlng lncipient carious lesions and/or stains from teeth by the applicatlon of a laser beam from a source such as a yttrlum-alumlnum-garnet la80r. In nelther of these - ~ , ? ~ ~

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132~2~0 patents 18 there provislon for autofocussing of the la~er beam, nor 18 there a provlslon for vlewlng the site through the handpiece. These aforementloned apparatus also lack provislon for the delivery of hlgh peak power TEM(oo) laser mode radlatlon, as thls radiation would normally destroy the fiber-optlc delivery devices. For example, five milli~oules Q-switched ~AG laser pulses would destroy the single mode fiber-optlc ends.
An apparatus and method for performlng laser surgery ls disclosed, in which a focussed laser beam is directed by a handpiece to an operational site, and is automatically focussed, so that the tissue modifying (ablatlon, cuttlng, melting, etc.) effect of the laser beam 18 located at a desired locus along the axis of the beam ln the sub~ect body. The handplece whlch is provided i8 supported by a novel articulated arm system which permits the handpiece to have six degrees of freedom. The novel arrangement which uses prisms permits the delivery of high peak power laser radlation ranging from the ultraviolet to the infrared.
Within the handpiece there is provided a dichroic reflector whlch recelve~ laser radiation passed through the articulatlng arm system from a laser source, the laser radlatlon (lncludlng a concentrlc allgnment beam) entering the handplece along an optlcal path at rlght anglcs to the optlool poth whlch 19 substontlolly t ~, , , :: , ,` '.. '.'' ' ' '` ' ' .': . .
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coinaident with the axls of the handpiece. A system of focussing lenses 15 provlded ln the handplece. A llght source i8 optlcally connected to the handplece through a flberoptlc bundle, whloh 18 connected to the proximal end of the handplece, llght passlng axlally along the handpiece axls and through the dlchrolc reflector and the varlable focus lens to the site, the observation light from the site passing through the focussing lens and the dichroic reflector into the fiberoptic bundle and to a control sy~tem which causes automatic focussing of the ad~ustable lens, to focus the laser radiatlon at a preselected dapth in the sub~ect body related to a rsference or benchmark in the body, which may be, for example, the endothelial cell layer of a cornea. The control system may take the form of an image scanner which delivers a signal to an error signal generator having a reference slgnal source thereln, and generating an error slgnal to an electromaynetlc lmpulser whlch controls a fluld cyllnder. The fluid cyllnder has a piston in lt moved by the electromagnetlc lmpulser, and is connected by a flexlble conduit to a variable volume chamber of the varlable focus lens. The handplece lower member may be rotated about the handpiece axls, and the handpiece 18 rotatable about the above mentloned lateral axis. The flberoptlc bundle and the fluld conduit are both flexlble, permltting unrestrained movement of the ,~. . .:. - : ,. ~
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.. - ,~ -132~2~0 handpieae.
Fig. 1 i8 a schematlc view of an apparatus ln accordance with the pressnt invantion.
Fig. lA is a detalled view of a part of the apparatus of Fig. 1, and a contact lens on a cornea.
Fig. 2 is a schematlc view showing portlons of the apparatus of Flg. 1, ln greater de~ail.
Fig. 3 is a view, partly ln section, of a dental handpiece in accordance with the present invention.
The following i8 a detailed descriptlon of the preferred embodlment.
Rsferrlng now to the drawlngs, wherein like or correspondlng reference numerals are used for llke or correspondlng parts throughout the several vlews, there 18 shown in Fig. 1 an apparatus 10 for performing laser surgery on an eye E. There is shown, in particular, the transparent cornea C having within it the endothelial layer EL, and with a contact lens 60 on the cornea; the lens 60 i8 optlonal. The herein disclosed apparatus utilizes the depth of the endothelium as a reference or landmark for achleving the delivery of laser radlatlon at a concentrated focus spot within the cornea at a deslred depth relatlve to the endothellum, regardless of the contour of the outer surfaae.
Because the contact lens 60 has the novel arrangement of havlng the plano slde to the cornea, the focusslng 18 extremely accurate and locallzed. In order to :. , ~ : ,: , , :,-, : . .
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132 ~2 ~0 locate the concentrated or focussed spot of the laser beam at the preclse locatlon, l.e., depth or distance from the corneal surface, the endothelial layer ls utlllzed as a reference for a focusslng system and a S varlable focu~ lens, described below. Although the hereln disclosed method and apparatus are particularly appllcable to treatlng the cornea wlth laser energy, the method and apparatus hereln dlsclosed are not necessarlly limited to that applicatlon.
The apparatus 10 includes a handpiece 12 adapted to be held ln the hand of a surgeon. Handplece 12 ls supported by an artlculating arm system 14, whlch recelves energy from an ablative laser 16. There may also be provided a relatively weak, aligning laser 18.
The laser 16 may be, for example, a high repetition rate, Q-switched YAG TEMoo mode system having an energy per pulse of about three milliJoules and a rep rate of the order of 2,000 pulses per second. The laser 16 i8 coaxially traversed by the beam from the allgnlng laser 18, which 18 preferable a vlslble, low powered CW
laser, and ls used for aohlevlng beam component allgnment, or optlonally as a source of illumination for the reference endothelial cell layer. Typlcally, the laser 18 is a three mllllwatt hellum neon laser.
The laser beam ln the Gaussian TEMoo mode can be dlffractlon llmlted focussed to a mlnimum spot slze on the order of about 10 mlcrons. The novel prlsm ; . ;
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-132~2~0 arrangement of the artlculating system of the present invention permits any number of hlgh power very ablative laser~ to be used, such a3 an excimer laser for wavelengths ~n the far W range, or an f-center laser for wavelengths in the near IR reglon.
Preferably, a movable platform or carriage (not shown) supports the la~er~ 16 and 18 and the articulating arm system 14.
Connected to the handpiece 12 is a flexible coher~nt fiberoptic bundle 20 and a flexible conduit 22, which are in turn conneGted to a monitoring and control system 24. A viewing instrument 26, such as a microscope, i8 provided, containing a beam splitter 28, and having adJacent to it a TV monitor 30. A surgeon S
vlews through thls instrument as shown.
The articulating arm system 14 18 shown in schematic form, and provides for 8iX degrees of movement of the handpiece 12. There i8 provided an outer tube 41a which i8 fixed, and in practice extends upwardly from prism 42. An inner tube 41b is axially rotatable relative to the outer tube 41a. This permits the remainder of articulating arm system 14 to rotate in a horizontal plane. The outer tube 41a is suitably anchored and supported, as mentioned above. Fixedly connected at right angles t~ the lnner tube 41b is an outer tube 43a, having within it a prism or other reflector 44. Axially rotatable in the outer tube 43a . , ,- ,, ,. ~. - ...-. ..
.. .. .. ~... .. -., ,. ~ .-, ~ . . ,- , 132~2~0 ls an lnner tube 43b. A tube 45a is connected at rlght angles to the lnner tube 43b, and ln lt 18 a reflector 46. A counter-welght 47 ls connected to the tube 45a by an arm 47a. Tube 45a has an enlarged end 45c ln whlch 18 mounted a tube 45d, and withln the tube 45d there ls a perforated tube 45e of smaller dlameter, provldlng a chamber 45f between them. Alr or gas is supplled to the chamber 45f through a conduit 48 supplied wlth alr from an a$r or gas source 49 through a pressure regulator 49a. An inner tube 45g 18 located within the perforated tube 45e, and is rotatably and axlally movable, belng supported on an almost frlctlonless alr cushlon between the inner tube 47b and the perforated tube 45e.
The inner tube 45g has at its outer end a reflector 50, and 18 secured at right angles to an inner tube 51a, there being an outer tube 51b which is axially rotatable with respect to it. The outer tube 51b forms part of a T-shaped housing 52 which includes a tube 53 tranQverse to the tube 51b. A lower tubular member 54 is axially rotatable relative to the tube 53.
Wlthln the houslng 53 are a dlchroic reflector 56, and adJacent the proximal end of handplece 12 and wlthin houslng 53 18 a relay lens 57. Withln the tubular member 54 18 a varlable focus lens generally deslgnated 58 and at lts dlstal end is a plano-convex coupllng lens 59, in engagement wlth the plano slde to ,..

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132~2-~0 the outer surface of cornea C. In Flg. lA, ths plano side of lens 50 18 in engagement wlth the surface of a hard contact len~ 60 through which the radlatlon passe~
and whlch serves as a guide surface.
Referring now to Fig. 2, there 18 shown the handplece 12, including the dichroic reflector 56, whlch is located at the ~uncture of an optical path through the tubes 51a and 51b, and an optical path along the axi~ of tubes 53 and 54. The variable focus lens 58 includes for example a negative lens 61 movable axially on guides 62, and a positive lens 63 fixed in posltion by a locking ring 64. A flexible bellows 66 is hermetlcally attached to the lenses 61 and 63:
flexible condult 22 extends from the flexible bellows 66, and iB ln fluid communication with the chamber formed by the lenses 61 and 63 and the flexible bellows 66.
The monltorlng and control system 24 includes a lens 72 in alignment with an end of the fiberoptic bundle 20, and dlchrolc reflectors 73 and 74. A light source 76 18 ln alignment wlth dlchroic reflector 73, and provides llght to the operatlng slte, through the lens 72, and flberoptlc bundle 20, and thence lnto the handplece 12, passlng through relay lens 57, dichroic reflector 56, the varlable focus lens 58, and coupllng lens 59. Alternatlvely, the lllumlnation provided by the allgnment laser 18 (Fig. 1) can serve to provide '" ' ' ' '' ~ ` '; ' ' , ' : , . . !; . , ~

132~2~0 the image of the endothelial cells, ln whlch case optical element 75a, 75b, which are bandpass ilters pas~lng only the wavelength of the alignment laser, are utllized. A televislon camera 77 18 in alignment with the partial reflector 74, to receive images of the slte, TV camera 77 being connected to the TV monitor 30 (Fig. 1).
Also forming a part of the monitoring and control system 24 is an image scanner 78, which receives an image from the sndothelial layer EL. The image scanner, by means of out-of-focus sensings, measures the departure of the optical system comprised of the variable focus lens 58, and lenses 59 and 57 from focus on the reference layer EL, i.e., it measure~ the focus condition. The scanner 78 delivers a signal representatlve thereof to an error signal generator 79.
Error slgnal generator 79 includes an internal reference standard, such as a pre-set voltage, and generates an error signal in proportion to the difference between the reference voltage and the voltage supplied from image scanner 78. rhe generated error signal is supplied to an electromagnetlc impulser 81 which, in response to the signal received, moves a piston rod 82 into or out of a fluid cylinder 83. The fluid cyllnder 83 18 fluid connected wlth the varlable volume chamber of varlable focus lens 58 by the flexible conduit 22. Thus, the focus of the ., . ~ . -.

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~32~2~0 variable len~ is changed in accordance with the variation of the thickness of the cornea C. The automatic ad~ustment of the variable lens with thickne~s variatlons of the cornea C assures that the laser beam focal point lies at a predetermlned fractlon of the corneal thickness since the focus condition of the variable lens system affects the surgical laser beam.
In use of the apparatus 10 shown in Figs. 1 and 2 of the drawings and hereinabove descrlbed, the handplece 12 i8 maneuvered into position so that the coupling lens 59 at the distal end thereof ls in engagement with the outer surface of the cornea C of the eye E under observation and treatment, as shown in Fig. 1. Alternatlvely, as shown in Flg. lA, the engagement surface may be a contact lens 60 positloned to cover the cornea and to provide a transparent guide surface. The positloning of handplece 12 is facllitated by the articulating arm system 14, which permits six degrees of freedom of movement of handpiece 12. Thus, the handpiece 12 may be moved or translated, along three mutually perpendlcular axes, and may be rotated about three mutually perpendlcular axes. As will be appreciated, rotational movement will be effec~ed by the axial rotational movement provided by ths inner and outer tubes 41a, 41b, etc., and linear and rotational movement is facilitated by the . . - . . . . .

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~ 32~2~0 structure lncluding the tubes 45d and 45g, and the alr bearing constructlon lncluding the perforated tube 45e.
Assumlng that the cornea C has a relatlvely normal thickness at the place where it i8 engaged by the coupllng lens 59, the focus dlstance of the bsnchmark endothelial layer EL wlll be "normal" and con~equently the image scanner will detect a sharp image of layer EL: when the slgnal generated by image scanner 78 ls compared by error signal generator 79 with the internal reference standard, error signal generator 79 will not produce an error signal. Consequently, there will be no change made to the variable focus lens 58, and when the laser 16 is fired, there will be produced a very high energy density, hlghly locallzed spot, at a preclse and automatlcally determined dlstance ln relation to the endothelial layer EL. As may be desirable, the laser is not fired when the foregoing condition is not obtained. The handplece 12 will be caused by the surgeon to move over the outer surface of the cornea C, for example in a radlal path as ln radlal keratotomy, and assumlng that lt engages a thlckness change, lt will be apparent that the plano end surface of coupling lens 59 wlll be moved away from the reference or benchmark endothellal layer EL. The lmage recelved by the lmage scanner 78 wlll be out of focus, and the lmage scanner 78 wlll therefore send a signal to the error signal generator 79 which will be .. . . .. .......... . ..
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".' , ' ~ ~, : ,, 132~2~0 different from the internal reference voltage of error slgnal generator 79. When a comparison is made, a dlfference between the two voltage signals occurs, and an error signal will be generated and sent to the electromagnetic lmpulser 81, resulting ln movement of the piston rod 82, and a change in the focal length of the variable focu~ lens 58. The correction is accomplished ln an extremely short period of time, so that the firlng of the laser 16, which may, as is typlcal, be under the control of the surgeon, be accompllshed without delay. The laser beam will be focussed so as to place the high energy, small diameter focus spot in the corneal layer at a desired, predetermined distance relat~ve to the location of the endothelial layer EL.
The surgeon, utilizing both the handpiece 12 and the viewing instrument 26, will be able to obtain an image of the site whlch may be substantlally the same as if he were looking lnto the dlstal end of the handplece 12. The lmage of the site will pass from the slte through the coupling lens 59, varlable lens 58, dlchrolc reflector 56, and relay lens 57 lnto the flberoptlc bundle 20, and thence through lens 72 to the beam splltter 74. The lmage wlll then pass to the TV
camera 77, and be transmltted to the TV monltor 30, the lmage appearlng via the beam splltter 28 occupie~ a small position of the viewing field ln the viewing ..

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~32~)2-~0 instrument 26. It wlll be appreciated that the vlewing instrument 26 and the handplece 12 may be maneuvered ~o as to be closely ad~acent to each other, for vlewing the same portlon of the Gornea C. Referring to Flg. 3, there i8 shown a handpiece 120 for dental appllcatlons, handpiece 120 being shown in con~unctlon with teeth T upon which dental work is to be performed.
The handplece 120 comprises T-shaped housing 52 formed by outer tube 51b and tube 53 transverse to it. Lower tubular member 54 is shown, rotatabls with respect to tube 53, and having wlthln it the variable focus lens 5~. Also shown in handpiece 120 are the dichroic reflector 56 and relay lens 57, with the fiberoptic bundle 20 connected to handpiece 120 at its proximal end. The conduit 22 is also shown, extending to the variable focus lens 58.
At the distal end of handplece 20, there is a reflector 121, whlch may take the form of a diverting prlsm. The diverting prism 121 will divert the light from the light source 76 to the target area on one of the teeth T, and the image thereof will be delivered to the image scanner 78, wlth the optlcal distance from lens 58 and the ~traight line distance of the diverting prlsm 121 to the dental target determlned by lmage scanner 78, and the focus of the light and laser beams varied in accordance therewith by the error signal generator 79, the electromagnetic impulser 81, 132~2~0 cylinder 83, and conduit 22. Since the ad~u~tment of the varlable focus lens 58 18 substantially lnstantaneou~, the dental operator may be able to effect removal of materlal on the dental target even though the dlstance between the dlverting prism 121 and the dental target wlll change due to either or both of the followlng condltlons. One condltlon is that the dental handpiece 120 may be moved 80 as to cause the beam to traverse a surface or region of the dental target whlch is curved, and the operator of the handpiece 120 will not be able to maintain the divertlng prlsm 121 at a preclse dlstance from the dental target as the beam ls moved over the curvlng surface thereof. The other condltion, which is also overcome by the present lnventlon, ls the lnabllity of a dental operator to maintaln the dental handplece and partlcularly the dlvertlng prism 121 at a precise dlstance, even from a plane surface, should such be encountered ln or on the teeth T. For elther of these causes or condltlons, lt wlll be appreclated that the physlcal dlstance from the dlvertlng prlsm 121 to the dental target slte wlll vary, but such varlation wlll be sensed, and there wlll be caused the automatlc focusslng of the locallzed energy focus spot of the laser beam on the surface of the dental target site through the above descrlbed exemplary focusslng apparatus.

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-: . - . :, .:: -~32 ~2 ~ 0 The claims and the speclflcatlon descrlbe the lnventlon presented, and the terms that are employed ln the clalms draw their meanlng from the use of such terms ln the speclflcatlon. Some terms employed in the prior art may be broader in meanlng than speciflcally employed hereln. Whenever there i8 a questlon between the broader deflnltlon of such term as used ln the prlor art and the more speclflc use of the term hereln, the more speclflc meanlng is meant.

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Claims

1. An apparatus for performing surgery by laser radiation at an operational site comprising:
(a) an elongate handpiece having first and second optical paths therein at right angles to each other, (b) a dichroic reflector in said handpiece inclined relative to said first and second optical paths, (c) a variable focus lens in said handpiece along said first optical path, (d) means for directing laser radiation to said dichroic reflector along said second optical path for reflection by said dichroic reflector along said first optical path to said variable focus lens, and (e) means connected to said handpiece for acquiring an image of the site.

2. The apparatus of claim 1, and further comprising a plano-convex coupling lens at the distal end of said handpiece along said first optical path and positioned with engaging the treatment site with the plano side to the treatment site.

3. The apparatus of claim 2, and further comprising a contact plano lens engaging said plano side of said coupling lens.

4. The apparatus of claim 2, wherein said plano lens is of sapphire.

5. The apparatus of claim 1, and a relay lens adjacent the proximal end of said handpiece and positioned along said first optical path for receiving an image of said site through said dichroic reflector.

6. The apparatus of claim 5, wherein said image acquiring means comprises an optical fiber having an end at the distal end of said handpiece and positioned to receive an image from said relay lens.

7. The apparatus of claim 1, and further comprising means for varying the focus of said variable focus lens means.

8. The apparatus of claim 1, said variable focus lens means comprising first and second lenses, means mounting one said lens in fixed position in said handpiece, means for guiding the other said lens along said first optical path, means including said first and second lenses defining an expansible chamber.

9. The apparatus of claim 8, and further comprising a source of fluid, and means for communicating said source of fluid with said chamber.

10. The apparatus of claim 9, and further comprising means for scanning an image of said site from said image acquiring means and for producing a signal representative of the image scanned, error signal generating means for receiving said signal and for generating an error signal, and control means for receiving said error signal and for causing said source to change the volume of fluid in said chamber.

11. The apparatus of claim 1, and further comprising means for receiving an image of said site from said image acquiring means and for actuating said variable focus lens means.

12. The apparatus of claim 1, and further comprising means for supporting said handpiece for rotational movement about the axis of said second optical path.

13. The apparatus of claim 1, and further comprising means for supporting said handpiece for movement with six degrees of freedom.

14. The apparatus of claim 13, wherein said image acquiring means comprises a flexible optical fiber connected to said handpiece, and wherein said variable focus lens has a flexible conduit connected thereto.

15. The apparatus of claim 1, and further comprising means for sensing the departure of the focus of said variable focus lens from a reference plane,, and means for changing said variable focus lens in response to the focus error.

16. The apparatus of claim 15, and further comprising a plano-convex coupling lens at the distal end of said handpiece.

17. The apparatus of claim 15, and further comprising means in said handpiece on the first optical axis for receiving radiation which has passed through said variable focus lens and for passing said radiation out of said handpiece at an angle to said first optical path.

18. The apparatus of claim 17, said angle being 45°.

19. The apparatus of claim 1, said image acquiring means comprising a fiberoptic connected to the proximal end of said handpiece with the end thereof on said first axis, a television camera and a television monitor connected to said television camera.

20. Apparatus for performing surgery upon a subject body comprising:
a source of laser radiation, means for receiving laser radiation from said source and for sharply focussing said laser radiation to a localized spot at a subject body, means for sensing the distance from a part of said apparatus to a reference in or on the subject body, and means for changing the position of said localized spot relative to the reference in the subject body in response to a change in the said distance sensed by said distance sensing means.

21. The apparatus of claim 20, said distance sensing means comprising second means for emitting radiation, and means for receiving emitted radiation reflected from the reference and for generating a control signal to said localized spot position changing means.

22. The apparatus of claim 20, said distance sensing means comprising a low power alignment laser beam for illuminating the reference.

23. The apparatus of claim 21, said second radiation emitting means comprising a source of light.

24. The apparatus of claim 23, said distance sensing means comprising means for scanning an image of said reference, and means for conducting light from said reference to said image scanning means.

25. The apparatus of claim 24, said localized spot position changing means comprising a variable focus lens.

26. The apparatus of claim 19, said apparatus further including a handpiece to be held and manipulated by a person, said position changing means comprising a variable focus lens in said handpiece.

27. The apparatus of claim 26, said handpiece having a dichroic reflector therein, a first optical path in said handpiece passing through said variable focus lens, means defining a second optical path in said handpiece transverse to said first optical path, said dichroic reflector located at the juncture of said optical paths.

28. The apparatus of claim 27, said apparatus further comprising a fiberoptic bundle connected to said handpiece for conducting light scattered from the reference layer into and from said handpiece along said first optical path.

29. The apparatus of claim 27 wherein said distance sensing means comprises said fiberoptic bundle, a source of light, means for introducing said light into said fiberoptic bundle, image scanning means for receiving the image of said reference and for generating a signal, and error signal generating means for receiving said signal and for generating an error signal.

30. The apparatus of claim 26, said apparatus further comprising a fiberoptic bundle connected to said handpiece to receive an image of the reference along said first optical path, said handpiece comprising an elongate, generally cylindrical member having proximal and distal ends, said fiberoptic bundle having an end located at said proximal end of said handpiece and having the terminal portion thereof in alignment with the first optical axis extending longitudinally through said cylindrical handpiece portion, a television camera, means for projecting an image of said reference to said television camera, and a television monitor connected with said television camera for displaying an image of said reference.

31. A method of performing surgery utilizing laser energy comprising:
(a) passing a light beam through a variable focus lens, (b) sensing the focus condition of said variable focus lens and an object and changing said variable focus lens to focus light on or at a predetermined distance from said object, (c) generating a laser beam, and (d) passing said laser beam through said variable focus lens after the changing of the focus of said lens.

32. The method of claim 31, wherein said sensing is by receiving light from said object and scanning said light, and thereafter generating a signal in response to the image scanned.

33. The method of claim 31, and further comprising passing said laser beam to a dichroic reflector located on and at an angle to the optical axis of said variable focus lens.

34. The method of claim 31, wherein said sensing is of the focus condition of said variable focus lens with respect to a reference in a transparent anatomical part.

35. The method of claim 31, wherein said sensing is of the focus condition of said variable focus lens and a dental target located on or in a tooth.