WO2004031837A1 - Device for reducing coherence - Google Patents
Device for reducing coherence Download PDFInfo
- Publication number
- WO2004031837A1 WO2004031837A1 PCT/EP2003/010074 EP0310074W WO2004031837A1 WO 2004031837 A1 WO2004031837 A1 WO 2004031837A1 EP 0310074 W EP0310074 W EP 0310074W WO 2004031837 A1 WO2004031837 A1 WO 2004031837A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- bundle
- sub
- divider
- cube
- light
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/10—Beam splitting or combining systems
- G02B27/14—Beam splitting or combining systems operating by reflection only
- G02B27/144—Beam splitting or combining systems operating by reflection only using partially transparent surfaces without spectral selectivity
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/10—Beam splitting or combining systems
- G02B27/14—Beam splitting or combining systems operating by reflection only
- G02B27/143—Beam splitting or combining systems operating by reflection only using macroscopically faceted or segmented reflective surfaces
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/10—Beam splitting or combining systems
- G02B27/14—Beam splitting or combining systems operating by reflection only
- G02B27/145—Beam splitting or combining systems operating by reflection only having sequential partially reflecting surfaces
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/48—Laser speckle optics
Definitions
- the invention relates to an arrangement for reducing the coherence of a light beam, in particular a laser light beam for illuminating an image surface or a sample.
- Light bundles are used to illuminate the sample in a microscope or to display light images on picture walls. Due to the relatively high temporal and spatial coherence of the laser light, interferences occur, which the observer perceives as different luminance levels or as annoying glitter. Such lighting structures are often referred to as "speckle".
- DE 195 01 525 C2 describes a method which is used to reduce the temporal coherence of the laser light.
- the light is guided through an optical plate which has a microstructured, phase-shifting radiation or radiation surface, or the light is directed onto a plate which has a reflective effect and is provided with such a surface structure. has a reflective effect and is provided with such a surface structure.
- the disadvantage here is that, due to the relatively large individual reflectors compared to the wavelength of the light, shadowing occurs, which results in an undesired weakening of the radiation intensity.
- honeycomb capacitors are used to implement the different optical path lengths, which have differently thick glass paths in the individual honeycombs, or optical prisms, with different glass paths being specified depending on the position of the prism, the success only occurs with radiation sources whose temporal coherence is relatively low , otherwise considerable glass path differences have to be realized and this is not possible with these means.
- the object of the invention is to find a further possibility for reducing coherence and thus for reducing speckle. the one in which the radiation intensity is weakened as little as possible.
- an arrangement for reducing the coherence comprises a device for beam splitting, at which an incident light beam is split into two sub-beams, a device for beam combining, at which the sub-beams are brought together again to form an outgoing light beam, and deflection elements which are located in the light paths of the sub-beams are positioned between these two devices, the light path lengths of the sub-bundles being different and the length difference being so great that the coherence of the wave trains / phase space cells in the sub-bundles is exceeded and thus their ability to interfere with one another is reduced or eliminated ,
- a first divider cube is provided as a device for beam splitting and a second divider cube as a device for beam combining, a first sub-bundle passing through the divider layer of the first divider cube, while a second sub-bundle is deflected at the divider layer.
- the first sub-bundle also passes through the divider layer, while the second sub-bundle is deflected by this divider layer in the direction of the first sub-bundle and thereby combines with the first sub-bundle to form the outgoing light bundle.
- a triangular prism is used as the device for beam splitting is provided, on the apex angle of which the incident light beam is directed so that a partial beam is deflected from the two boundary surfaces of the triangular prism, and a splitter cube is provided as a device for beam combining, a first partial beam passing through the partial layer of the splitter cube while the second partial beam is directed towards the divider layer of the divider cube in such a way that it is deflected by the divider layer in the direction of the first sub-bundle and thereby combines with the first sub-bundle to form the outgoing light bundle.
- a laser for example an F 2 excimer laser, is preferably provided as the radiation source, and the light path of the second sub-beam is at least 14 mm longer than the light path of the first sub-beam.
- At least one of the partial beams is arranged in the light path for changing the wavefront.
- These means can be designed, for example, as an optical element with a radiation or radiation surface structured in the micrometer range, as a telescope or as a Dove prism. Kick the Radiation through this, the wavefront is changed so that when the sub-beams are later combined, the non-interference-capable radiation components are mixed more efficiently.
- the divider cubes used have a division ratio of 50:50, i.e. in the case of beam splitting, the incident light beam is split into approximately the same radiation components.
- a mirror system is additionally present in the arrangement, by means of which radiation components that are otherwise decoupled from the device for beam combining are directed back to the device for beam combining and are coupled there into the light paths of the partial bundles.
- Fig.l the basic structure of the arrangement according to the invention in an embodiment with two divider cubes
- Fig.2 the basic structure of the arrangement according to the invention in an embodiment with a triangular prism and a divider cube.
- an incident light beam 1 strikes a divider cube 2, which has a divider layer 3.
- a divider cube 2 which has a divider layer 3.
- Divider layer 3 becomes the incident light beam 1 in one Sub-bundle 4 and a sub-bundle 5 split.
- the sub-beam 4 corresponds to the radiation component that passes through the splitter layer 3.
- the sub-bundle 4 is directed to a second divider cube 6 with a divider layer 7.
- the partial bundle 4 passes through the partial layer 7.
- the second sub-bundle 5 which corresponds to the radiation component of the incident light bundle 1 deflected at the sub-layer 3, strikes a first mirror 8, is deflected by the latter in the direction of a second mirror 9 and is by this onto the sub-layer 7 of the second cube 6 directed.
- the partial bundle 5 is deflected at the dividing layer 7, in the same direction in which the partial bundle 4 passes through the dividing layer 7.
- the two sub-bundles 4, 5 combine to form an outgoing light bundle 10, which now has a reduced coherence compared to the incident light bundle 1, so that the individual wave trains or phase space cells of the light bundle 10 can no longer interfere with one another and thereby also the formation of speckle is reduced and the light beam 10 can be used without the disadvantages described above for illuminating a sample or for illuminating a surface.
- a Dove prism 11 is positioned between the two mirrors 8 and 9, through which the partial bundle 5 runs and thereby a side Exchange of experiences. This contributes to a better mixture of non-interference-capable wave trains when the two sub-beams 4, 5 are combined to form the outgoing light beam 10.
- two further mirrors 12 and 13 are provided, which ensure that the otherwise unused radiation portions of the sub-beam 4, which at the The divider layer 7 is deflected in the direction of the mirror, or the radiation components of the partial beam 5, which pass through the divider layer 7 in the direction of the mirror 12, are deflected at the mirror 12 to the mirror 13 and in again via the mirror 13 and the divider layer 3 the partial bundles 4, 5 are coupled in, a portion of the returned radiation components on the dividing layer 3 being deflected in the direction of the dividing cube 6 and the remaining portion through the divider layer 3 passes through and merges with the sub-bundle 5.
- an incident light bundle 1 strikes a triangular prism 14 which is positioned in the light bundle 1 such that approximately the same sub-bundles 17 and 18 run from its interfaces 15 and 16.
- the sub-bundle 17 is directed via a mirror 19 at a divider cube 21 with a divider layer 20 through which the sub-bundle 17 runs.
- the sub-bundle 18 is likewise directed onto the divider layer 20 via two mirrors 22 and 23 and deflected by the latter in the direction which the sub-bundle 17 passing through the divider layer 20 also takes. Both sub-bundles 17, 18 are combined to form an outgoing light bundle 24 which, as in the exemplary embodiment according to FIG. 1 mentioned at the beginning, is again characterized by reduced coherence.
- devices for influencing the wavefront for example a Dove prism, a telescope, preferably a Kepler telescope, can be used in one of the sub-bundles 17, 18 or in both sub-bundles 17, 18 , or an optical element with a microstructured surface can be provided.
- a mirror system can also be provided here, similar to that in FIG. 1, which directs the radiation components, which would otherwise be uselessly coupled out on the divider layer 20, back onto the triangular prism 14. It is conceivable that Coupling radiation components into the light beam 1 with the aid of a partially reflecting element, which is placed, for example, at an angle of 45 ° in the incident light beam 1 and to direct it to the apex angle of the triangular prism 14.
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP03798900A EP1543374A1 (en) | 2002-09-27 | 2003-09-11 | Device for reducing coherence |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE10245231A DE10245231A1 (en) | 2002-09-27 | 2002-09-27 | Arrangement for reducing coherence |
DE10245231.8 | 2002-09-27 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2004031837A1 true WO2004031837A1 (en) | 2004-04-15 |
WO2004031837A8 WO2004031837A8 (en) | 2004-10-28 |
Family
ID=31969669
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP2003/010074 WO2004031837A1 (en) | 2002-09-27 | 2003-09-11 | Device for reducing coherence |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP1543374A1 (en) |
DE (1) | DE10245231A1 (en) |
WO (1) | WO2004031837A1 (en) |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4511220A (en) * | 1982-12-23 | 1985-04-16 | The United States Of America As Represented By The Secretary Of The Air Force | Laser target speckle eliminator |
US4600308A (en) * | 1983-10-21 | 1986-07-15 | Rockwell International Corporation | Phase-matching arrayed telescopes with a corner-cube-bridge metering rod |
EP0470555A1 (en) * | 1990-08-06 | 1992-02-12 | Elop- Electrooptics Industries Ltd. | Novel reversing prism |
US6191887B1 (en) * | 1999-01-20 | 2001-02-20 | Tropel Corporation | Laser illumination with speckle reduction |
WO2001057581A2 (en) * | 2000-02-07 | 2001-08-09 | Silicon Light Machines | Method and apparatus for reducing laser speckle using polarization averaging |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2536023B2 (en) * | 1988-02-29 | 1996-09-18 | 株式会社ニコン | Exposure apparatus and exposure method |
US5153773A (en) * | 1989-06-08 | 1992-10-06 | Canon Kabushiki Kaisha | Illumination device including amplitude-division and beam movements |
US5233460A (en) * | 1992-01-31 | 1993-08-03 | Regents Of The University Of California | Method and means for reducing speckle in coherent laser pulses |
US6238063B1 (en) * | 1998-04-27 | 2001-05-29 | Nikon Corporation | Illumination optical apparatus and projection exposure apparatus |
JP2001296503A (en) * | 2000-04-13 | 2001-10-26 | Mitsubishi Heavy Ind Ltd | Device for reducing speckle |
-
2002
- 2002-09-27 DE DE10245231A patent/DE10245231A1/en not_active Withdrawn
-
2003
- 2003-09-11 WO PCT/EP2003/010074 patent/WO2004031837A1/en not_active Application Discontinuation
- 2003-09-11 EP EP03798900A patent/EP1543374A1/en not_active Withdrawn
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4511220A (en) * | 1982-12-23 | 1985-04-16 | The United States Of America As Represented By The Secretary Of The Air Force | Laser target speckle eliminator |
US4600308A (en) * | 1983-10-21 | 1986-07-15 | Rockwell International Corporation | Phase-matching arrayed telescopes with a corner-cube-bridge metering rod |
EP0470555A1 (en) * | 1990-08-06 | 1992-02-12 | Elop- Electrooptics Industries Ltd. | Novel reversing prism |
US6191887B1 (en) * | 1999-01-20 | 2001-02-20 | Tropel Corporation | Laser illumination with speckle reduction |
WO2001057581A2 (en) * | 2000-02-07 | 2001-08-09 | Silicon Light Machines | Method and apparatus for reducing laser speckle using polarization averaging |
Also Published As
Publication number | Publication date |
---|---|
EP1543374A1 (en) | 2005-06-22 |
WO2004031837A8 (en) | 2004-10-28 |
DE10245231A1 (en) | 2004-04-01 |
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