US20010053033A1 - Counter-rotating anamorphic prism assembly with variable spacing - Google Patents
Counter-rotating anamorphic prism assembly with variable spacing Download PDFInfo
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- US20010053033A1 US20010053033A1 US09/365,102 US36510299A US2001053033A1 US 20010053033 A1 US20010053033 A1 US 20010053033A1 US 36510299 A US36510299 A US 36510299A US 2001053033 A1 US2001053033 A1 US 2001053033A1
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- 238000000034 method Methods 0.000 claims description 4
- 230000003287 optical effect Effects 0.000 claims description 4
- 238000006073 displacement reaction Methods 0.000 description 9
- 239000000463 material Substances 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 239000005350 fused silica glass Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000001459 lithography Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000012804 iterative process Methods 0.000 description 1
- 238000012806 monitoring device Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B17/00—Systems with reflecting surfaces, with or without refracting elements
-
- 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
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
- G02B27/0938—Using specific optical elements
- G02B27/095—Refractive optical elements
- G02B27/0972—Prisms
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
- G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
- G02B26/0875—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more refracting elements
- G02B26/0883—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more refracting elements the refracting element being a prism
-
- 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
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
-
- 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
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
- G02B27/0911—Anamorphotic systems
Definitions
- This invention relates to optics, and more particularly to conversion of a laser beam with an elliptical cross section to a beam with a circular cross section.
- Elliptically shaped (in cross section) light beams output from a laser can be converted into a more desirable circular beam by using a pair of prisms.
- the output beam from a laser is often in the cross-sectional shape of an ellipse; however, the elliptical shape does not lend itself to optimal performance of associated systems, thereby giving rise to various techniques for converting the elliptical beam into a circular one.
- Such beam conversion is useful, e.g., in laser beam scanning lithography where a group of parallel laser beams are modulated and scanned over a photosensitive medium to form an image on the medium. Applications are, for instance, in the semiconductor industry for lithography for integrated circuits.
- an anamorphic assembly is an optical system providing two different magnifications along two perpendicular axes such as the present assembly where prisms convert an elliptically cross sectioned laser beam into a circularly shaped cross sectioned beam.
- the prisms are linked such that the first prism translates and rotates simultaneously towards or away from the axis of an input laser beam. Meanwhile, the second prism rotates towards or away from the axis of the input laser beam in a counter-rotating relationship with the first prism.
- a first prism mount upon which the first prism is attached, has a distal end which is attached to the base and a proximal end which is attached to the slide.
- a second prism mount upon which the second prism is attached, also has a distal end and a proximal end; however, this distal end is attached to the slide and the proximal end is attached to the base.
- FIG. 1 shows a view of the present counter-rotating anamorphic prism assembly.
- FIG. 2 shows a view of the FIG. 1 counter-rotating anamorphic prism assembly in the negative extreme position.
- FIG. 3 shows a view of the counter-rotating anamorphic prism assembly of FIG. 1 in the positive extreme position.
- FIG. 4 shows a view of the angular adjustment member and the first distal pivot of FIG. 1.
- FIG. 5 shows a view of the anamorphic prism assembly, the transverse displacement of the laser beam, the angles of rotation of the prisms, and the angles of incidence and refraction of the laser beam through the assembly of FIG. 1.
- FIG. 6 shows a view of a prism and the incident area.
- FIG. 1 illustrates an optical apparatus in accordance with this invention.
- the adjustable prism apparatus 2 has a base 4 which allows removal of an associated cover (not shown) and also allows easy access to the internal assembly contained within and which will be discussed in detail below.
- base 4 On base 4 is mounted a slide 6 which moves translationally over a specified range.
- Prism apparatus 2 further includes a first prism mount 8 and a second prism mount 10 mounted to base 4 and slide 6 .
- Slide 6 translates on base 4 by slide adjustment member 16 , which is, e.g., an adjustment screw anchored to base 4 in this embodiment.
- Slide adjustment member 16 has a ball end facing towards slide 6 and can be translated towards or away from slide 6 by rotating it about its own axis.
- Slide 6 is maintained in contact with slide adjustment member 16 at contact point 50 by a small spring force (e.g., 4 lb. force, nominal) acting on slide 6 (the spring is not shown); slide 6 is not rigidly fastened to slide adjustment member 16 thus allowing the rotation of member 16 about its axis.
- a small spring force e.g., 4 lb. force, nominal
- First prism mount 8 has two pivots located respectively at both its ends.
- First distal pivot 30 is located at the top of first prism mount 8 , called first distal end 26
- first proximal pivot 32 is located at the lower end of first prism mount 8 , called first proximal end 28 .
- first distal pivot 30 is in contact with angular adjustment member 18 , which is described in further detail below for FIG. 4.
- the first distal and proximal pivots 30 , 32 are collinearly aligned in first prism mount 8 , but this does not preclude noncollinear arrangements in other embodiments.
- First distal pivot 30 is secured onto base 4 near angular adjustment member 18 , located at the top of base 4 , and first proximal pivot 32 is secured onto slide 6 . Also, first distal pivot 30 is held within a slotted channel in first prism mount 8 (slot is not shown) to allow the translation of slide 6 .
- Second prism mount 10 also has two pivots located at both ends. Second distal pivot 38 is located near the top of prism mount 10 in second distal end 34 and second proximal pivot 40 is located near the bottom of prism mount 10 in second proximal end 36 . Second distal and proximal pivots 38 , 40 are also aligned collinearly, but again this does not preclude a noncollinear arrangement in other embodiments.
- second distal pivot 38 is secured onto slide 6 and second proximal pivot 40 is secured onto base 4 .
- Second distal pivot 38 is also held within a slotted channel on second prism mount 10 (slot is not shown) to allow the translation of slide 6 .
- All four pivots 30 , 32 , 38 , 40 are fastened to either base 4 or slide 6 with, e.g., dowels (not shown) which allows the rotation of the prism mounts 8 , 10 about their respective pivots.
- First distal pivot 30 is further attached to angular adjustment member 18 which is used to correct output laser beam 24 for manufacturing error in apparatus 2 or in input laser beam 20 angular errors. Operation of angular adjustment member 18 is described in greater detail below.
- First prism 12 is mounted onto first prism mount 8 at first proximal end 28 with an adhesive in such a way that a first entrant face 42 of first prism 12 is substantially coplanar with first proximal pivot 32 .
- FIG. 2 shows the translation towards the negative extreme position of slide 6 through a distance, d, relative to base 4 .
- slide adjustment member 16 is rotated about its axis to translate slide 6 parallel and towards input laser beam 20 .
- first prism mount 8 to rotate about first distal pivot 30 as first proximal end 28 rotates towards input laser beam 20 .
- second distal pivot 38 is linearly translated through distance, d, towards input laser beam 20 .
- second prism mount 10 to rotate about second proximal pivot 40 .
- the simultaneous rotations of first and second prism mounts 8 , 10 result in the rotation and translation of first prism 12 and the rotation of second prism 14 in a counter-rotating manner.
- first prism 12 and second 14 are mounted such that input laser beam 20 is incident upon entrant faces 42 , 46 and perpendicularly to the axis of first and second proximal pivots 32 , 40 , respectively.
- a sweep of beams may also be applied in another embodiment.
- Such a sweep of beams is preferably illuminated upon first entrant face 42 such that the beams are coplanar with each other and this plane is parallel with the axis of first and second proximal pivots 32 , 40 , respectively.
- the true circularity of the resulting output laser beam 24 can be monitored with a change coupled device (CCD) camera (camera not shown) or any commercially available beam monitoring device.
- CCD change coupled device
- Such a camera can be utilized with a beam splitter and placed downstream of prism apparatus 2 .
- another type of conventional camera, utilized with a beam splitter may be placed either upstream or downstream of prism apparatus 2 , but it is preferable to locate a camera downstream to monitor the circularity of the cross section of output laser beam 24 .
- FIG. 3 shows the translation towards the extreme positive position of slide 6 through a distance, d, relative to base 4 .
- slide adjustment member 16 is rotated about its axis to translate slide 6 parallel and away from input laser beam 20 .
- first prism mount 8 to rotate about first distal pivot 30 as first proximal end 28 rotates away from input laser beam 20 .
- second distal pivot 38 is linearly translated through distance, d, away from input laser beam 20 .
- second prism mount 10 rotates about second proximal pivot 40 and the simultaneous rotations of first and second prism mounts 8 , 10 further results in the rotation and translation of first prism 12 and the rotation of second prism 14 in a counter-rotating manner opposite from the direction as shown in FIG. 2.
- FIG. 4 shows angular adjustment member 18 of FIG. 1 which is used to correct output laser beam 24 angle errors.
- Angular adjustment member 18 is shown as an adjustment screw which is screwed into base 4 in this embodiment.
- the axis of output laser beam 24 might deviate from the axis of input laser beam 20 due either to manufacturing errors in the mechanical linkages and prisms 12 , 14 or in input laser beam 20 angular errors.
- correction of output laser beam 24 angle is effected by rotating angular adjustment member 18 about its own axis. This rotation translates first distal pivot 30 in a parallel direction either towards or away from input laser beam 20 and this translation adjusts the angle of incidence for input laser beam 20 with first prism 12 to effect a beam correction.
- FIG. 5 shows geometrically the relationship between first prism 12 and second prism 14 .
- the input laser beam 20 enters first entrant face 42 at angle A 1 , which is the angle of incidence of input laser beam 20 at first entrant face 42 .
- angle B 1 which is the angle of refraction of input laser beam 20 at first entrant face 42 .
- Input laser beam 20 again refracts as it passes first refractant face 44 defining angle A 2 , which is the angle of incidence of input laser beam 20 at first refractant face 44 , and angle B 2 , which is the angle of refraction of input laser beam 20 at first refractant face 44 .
- Input laser beam 20 is designated intermediate refracted laser beam 22 as it passes from first prism 12 to second prism 14 .
- This intermediate refracted beam 22 then enters second prism 14 defining angle A 3 , which is the angle of incidence of intermediate refracted laser beam 22 at second entrant face 46 , and angle B 3 , which is the angle of refraction of intermediate refracted laser beam 22 at second entrant face 46 .
- angle A 3 is the angle of incidence of intermediate refracted laser beam 22 at second entrant face 46
- angle B 3 which is the angle of refraction of intermediate refracted laser beam 22 at second entrant face 46 .
- intermediate beam 22 passes second refractant face 48 , it defines angle A 4 , which is the angle of incidence of intermediate refracted laser beam 22 at second refractant face 48 , and angle B 4 , which is the angle of refraction of intermediate refracted laser beam 22 at second refractant face 48 .
- the initial input laser beam 20 enters first prism 12 and finally emerges from second prism 14 as output laser beam 24 .
- the linear distance between where input laser beam 20 enters first entrant face 42 and where output laser beam 24 exits second refractant face 48 is the transverse displacement, t. Transverse displacement, t, is ideally held constant over the range of motion by prism apparatus 2 .
- the angular difference between input laser beam 20 and output laser beam 24 is preferably minimized by prism apparatus 2 in maintaining an angular error of approximately 7.5 arc-min at the negative extreme in FIG. 2 and an angular error of approximately 6.0 arc-min at the positive extreme in FIG. 3.
- FIG. 6 shows the dimensions of first and second prisms 12 , 14 , respectively.
- Both prisms 12 , 14 are defined by a prism height PH and a prism width PW which are preferably equal in one embodiment.
- Prisms 12 , 14 are further defined by a prism length PL and an apex angle ⁇ .
- the preferable area upon which input laser beam 20 is incident upon first and second prism 12 , 14 is bordered by outside frame OF.
- the prism material for this embodiment is fused silica. However, this does not preclude the use of other materials suitable for the use of prisms.
- the aforementioned dimensions for one embodiment are shown in the following table. Dimension Value ⁇ (degrees) 15.37° PH 25.40 mm PW 25.40 mm PL 12.23 mm OF 3.00 mm
- the wavelength of input laser beam 20 which is to be circularized, is 257.25 nm in one particular embodiment. Because prism apparatus 2 circularizes elliptical laser beams with a variable transverse and lateral radius, apparatus 2 operates over a range of laser beam cross sections. Apparatus 2 is such that first and second prism mounts 8 , 10 , respectively, are in a nominal position when the transverse radius of the input laser beam 20 measures 0.435 mm and the lateral radius measures 0.223 mm. Slide adjustment member 16 may then be adjusted to translate slide 6 to the negative extreme position shown in FIG. 2 to accommodate a laser beam with a minimum transverse radius of 0.348 mm and to the positive extreme position shown in FIG.
- the absolute value of change in rotation of PI which is the angle between first entrant face 42 and a plane perpendicular to an axis of input laser beam 20 , is related to the absolute value of translational distance, d, which slide 6 travels by the following:
- ⁇ first prism tan ⁇ 1 ( d/L 1 )
- L 1 is the length from first distal pivot 30 to first proximal pivot 32 .
- P 2 which is the angle between second entrant face 46 and the plane perpendicular to an axis of input laser beam 20 , is also related to the absolute value of translational distance, d, by the following:
- ⁇ second prism tan ⁇ 1 ( d/L 2 )
- L 2 is the length from second distal pivot 38 to second proximal pivot 40 .
- a third value, L 3 is the distance from first proximal pivot 32 to second proximal pivot 40 .
- All three values, L 1 , L 2 , and L 3 are chosen to minimize the angular displacement and changes in transverse displacement, t, of output laser beam 24 over the above range of scale factors.
- the changes in rotation PI, P 2 of first and second prisms 12 , 14 , respectively, are such that the changes occur in a counter-rotating manner as discussed above.
Abstract
Description
- 1. Field of the Invention
- This invention relates to optics, and more particularly to conversion of a laser beam with an elliptical cross section to a beam with a circular cross section.
- 2. Description of Related Art
- Elliptically shaped (in cross section) light beams output from a laser can be converted into a more desirable circular beam by using a pair of prisms. The output beam from a laser is often in the cross-sectional shape of an ellipse; however, the elliptical shape does not lend itself to optimal performance of associated systems, thereby giving rise to various techniques for converting the elliptical beam into a circular one. Such beam conversion is useful, e.g., in laser beam scanning lithography where a group of parallel laser beams are modulated and scanned over a photosensitive medium to form an image on the medium. Applications are, for instance, in the semiconductor industry for lithography for integrated circuits.
- These methods of converting such beam cross sections usually involve transmitting a laser beam through a pair of prisms and then rotating and translating the prisms in relation to each other until the desired cross section was achieved. An incident laser beam is applied to the prism pair, and then an iterative process begins of manipulating the prisms relative to each other. This not only increases post adjustment alignment time for downstream optics, but this also increases the complexity of downstream assemblies due to significant angular and transverse displacement of the output beam relative to the input beam. Therefore, there is a need to be able to quickly adjust an anamorphic prism pair to change the ellipticity of an input laser beam while minimizing angular and transverse beam displacements resulting from the adjustments.
- In accordance with the invention, the above problem is overcome by linking an anamorphic pair of prisms, where a first prism simultaneously rotates counter to a second prism, by mechanical linkages. An anamorphic assembly is an optical system providing two different magnifications along two perpendicular axes such as the present assembly where prisms convert an elliptically cross sectioned laser beam into a circularly shaped cross sectioned beam. The prisms are linked such that the first prism translates and rotates simultaneously towards or away from the axis of an input laser beam. Meanwhile, the second prism rotates towards or away from the axis of the input laser beam in a counter-rotating relationship with the first prism. These movements are effected by a single slide adjustment member which translates a slide upon which both prisms are attached.
- A first prism mount, upon which the first prism is attached, has a distal end which is attached to the base and a proximal end which is attached to the slide. A second prism mount, upon which the second prism is attached, also has a distal end and a proximal end; however, this distal end is attached to the slide and the proximal end is attached to the base. This arrangement allows the simultaneous adjustment of both prisms using a single slide adjustment member while maintaining the circularity of an output beam cross section over a range of elliptical input beam cross sections. This arrangement also allows for minimizing the angular and transverse displacement of the output beam relative to the input beam.
- Furthermore, there is an associated method of simultaneously adjusting a prism pair where a laser beam is input into the entrant face of the first prism, then the slide adjustment member is adjusted. This adjusting rotates and translates the first prism towards or away from the laser beam and rotates the second prism simultaneously towards or away from the laser beam in a fixed counter-rotating manner.
- FIG. 1 shows a view of the present counter-rotating anamorphic prism assembly.
- FIG. 2 shows a view of the FIG. 1 counter-rotating anamorphic prism assembly in the negative extreme position.
- FIG. 3 shows a view of the counter-rotating anamorphic prism assembly of FIG. 1 in the positive extreme position.
- FIG. 4 shows a view of the angular adjustment member and the first distal pivot of FIG. 1.
- FIG. 5 shows a view of the anamorphic prism assembly, the transverse displacement of the laser beam, the angles of rotation of the prisms, and the angles of incidence and refraction of the laser beam through the assembly of FIG. 1.
- FIG. 6 shows a view of a prism and the incident area.
- Use of the same reference symbols in different figures indicates similar or identical items.
- FIG. 1 illustrates an optical apparatus in accordance with this invention. The adjustable prism apparatus2 has a base 4 which allows removal of an associated cover (not shown) and also allows easy access to the internal assembly contained within and which will be discussed in detail below. On base 4 is mounted a
slide 6 which moves translationally over a specified range. Prism apparatus 2 further includes afirst prism mount 8 and asecond prism mount 10 mounted to base 4 andslide 6. -
Slide 6 translates on base 4 byslide adjustment member 16, which is, e.g., an adjustment screw anchored to base 4 in this embodiment.Slide adjustment member 16 has a ball end facing towardsslide 6 and can be translated towards or away fromslide 6 by rotating it about its own axis.Slide 6 is maintained in contact withslide adjustment member 16 atcontact point 50 by a small spring force (e.g., 4 lb. force, nominal) acting on slide 6 (the spring is not shown);slide 6 is not rigidly fastened to slideadjustment member 16 thus allowing the rotation ofmember 16 about its axis. -
First prism mount 8 has two pivots located respectively at both its ends. Firstdistal pivot 30 is located at the top offirst prism mount 8, called firstdistal end 26, and firstproximal pivot 32 is located at the lower end offirst prism mount 8, called firstproximal end 28. Furthermore, firstdistal pivot 30 is in contact withangular adjustment member 18, which is described in further detail below for FIG. 4. The first distal andproximal pivots first prism mount 8, but this does not preclude noncollinear arrangements in other embodiments. Firstdistal pivot 30 is secured onto base 4 nearangular adjustment member 18, located at the top of base 4, and firstproximal pivot 32 is secured ontoslide 6. Also, firstdistal pivot 30 is held within a slotted channel in first prism mount 8 (slot is not shown) to allow the translation ofslide 6.Second prism mount 10 also has two pivots located at both ends. Seconddistal pivot 38 is located near the top ofprism mount 10 in seconddistal end 34 and secondproximal pivot 40 is located near the bottom ofprism mount 10 in secondproximal end 36. Second distal andproximal pivots first prism mount 8, seconddistal pivot 38 is secured ontoslide 6 and secondproximal pivot 40 is secured onto base 4. Seconddistal pivot 38 is also held within a slotted channel on second prism mount 10 (slot is not shown) to allow the translation ofslide 6. All fourpivots slide 6 with, e.g., dowels (not shown) which allows the rotation of theprism mounts distal pivot 30 is further attached toangular adjustment member 18 which is used to correctoutput laser beam 24 for manufacturing error in apparatus 2 or ininput laser beam 20 angular errors. Operation ofangular adjustment member 18 is described in greater detail below. -
First prism 12 is mounted ontofirst prism mount 8 at firstproximal end 28 with an adhesive in such a way that afirst entrant face 42 offirst prism 12 is substantially coplanar with firstproximal pivot 32.Second prism 14 is also mounted onto secondproximal end 36 in such a way that asecond entrant face 46 is substantially coplanar with secondproximal pivot 40. It is not necessary that first and second entrant faces 42, 46, respectively, and first and secondproximal pivots proximal pivots prisms - FIG. 2 shows the translation towards the negative extreme position of
slide 6 through a distance, d, relative to base 4. As the input laser beam 20 (from a conventional laser source) is illuminated throughfirst entrant face 42,slide adjustment member 16 is rotated about its axis to translateslide 6 parallel and towardsinput laser beam 20. This causesfirst prism mount 8 to rotate about firstdistal pivot 30 as firstproximal end 28 rotates towardsinput laser beam 20. Simultaneously, seconddistal pivot 38 is linearly translated through distance, d, towardsinput laser beam 20. This in turn causessecond prism mount 10 to rotate about secondproximal pivot 40. The simultaneous rotations of first and second prism mounts 8, 10 result in the rotation and translation offirst prism 12 and the rotation ofsecond prism 14 in a counter-rotating manner. - Additionally, because
first prism 12 and second 14 are mounted such thatinput laser beam 20 is incident upon entrant faces 42, 46 and perpendicularly to the axis of first and second proximal pivots 32, 40, respectively, a sweep of beams may also be applied in another embodiment. Such a sweep of beams is preferably illuminated uponfirst entrant face 42 such that the beams are coplanar with each other and this plane is parallel with the axis of first and second proximal pivots 32, 40, respectively. The true circularity of the resultingoutput laser beam 24 can be monitored with a change coupled device (CCD) camera (camera not shown) or any commercially available beam monitoring device. Such a camera can be utilized with a beam splitter and placed downstream of prism apparatus 2. In another embodiment, another type of conventional camera, utilized with a beam splitter, may be placed either upstream or downstream of prism apparatus 2, but it is preferable to locate a camera downstream to monitor the circularity of the cross section ofoutput laser beam 24. - FIG. 3 shows the translation towards the extreme positive position of
slide 6 through a distance, d, relative to base 4. Again, asinput laser beam 20 is illuminated throughfirst entrant face 42,slide adjustment member 16 is rotated about its axis to translateslide 6 parallel and away frominput laser beam 20. This causesfirst prism mount 8 to rotate about firstdistal pivot 30 as firstproximal end 28 rotates away frominput laser beam 20. Simultaneously, seconddistal pivot 38 is linearly translated through distance, d, away frominput laser beam 20. Again, this causessecond prism mount 10 to rotate about secondproximal pivot 40 and the simultaneous rotations of first and second prism mounts 8, 10 further results in the rotation and translation offirst prism 12 and the rotation ofsecond prism 14 in a counter-rotating manner opposite from the direction as shown in FIG. 2. - FIG. 4 shows
angular adjustment member 18 of FIG. 1 which is used to correctoutput laser beam 24 angle errors.Angular adjustment member 18 is shown as an adjustment screw which is screwed into base 4 in this embodiment. Afterslide 6 andprisms output laser beam 24 might deviate from the axis ofinput laser beam 20 due either to manufacturing errors in the mechanical linkages andprisms input laser beam 20 angular errors. Therefore, in order to keep the axis ofoutput laser beam 24 substantially parallel with the axis ofinput laser beam 20, correction ofoutput laser beam 24 angle is effected by rotatingangular adjustment member 18 about its own axis. This rotation translates firstdistal pivot 30 in a parallel direction either towards or away frominput laser beam 20 and this translation adjusts the angle of incidence forinput laser beam 20 withfirst prism 12 to effect a beam correction. - FIG. 5 shows geometrically the relationship between
first prism 12 andsecond prism 14. Theinput laser beam 20 entersfirst entrant face 42 at angle A1, which is the angle of incidence ofinput laser beam 20 atfirst entrant face 42. Asinput laser beam 20 passes throughfirst prism 12, it defines angle B1, which is the angle of refraction ofinput laser beam 20 atfirst entrant face 42.Input laser beam 20 again refracts as it passesfirst refractant face 44 defining angle A2, which is the angle of incidence ofinput laser beam 20 atfirst refractant face 44, and angle B2, which is the angle of refraction ofinput laser beam 20 atfirst refractant face 44.Input laser beam 20 is designated intermediate refractedlaser beam 22 as it passes fromfirst prism 12 tosecond prism 14. This intermediate refractedbeam 22 then enterssecond prism 14 defining angle A3, which is the angle of incidence of intermediate refractedlaser beam 22 atsecond entrant face 46, and angle B3, which is the angle of refraction of intermediate refractedlaser beam 22 atsecond entrant face 46. The angles offirst prism 12 andsecond prism 14 are discussed in greater detail below. Finally, asintermediate beam 22 passessecond refractant face 48, it defines angle A4, which is the angle of incidence of intermediate refractedlaser beam 22 atsecond refractant face 48, and angle B4, which is the angle of refraction of intermediate refractedlaser beam 22 atsecond refractant face 48. The initialinput laser beam 20 entersfirst prism 12 and finally emerges fromsecond prism 14 asoutput laser beam 24. The linear distance between whereinput laser beam 20 entersfirst entrant face 42 and whereoutput laser beam 24 exitssecond refractant face 48 is the transverse displacement, t. Transverse displacement, t, is ideally held constant over the range of motion by prism apparatus 2. Furthermore, the angular difference betweeninput laser beam 20 andoutput laser beam 24 is preferably minimized by prism apparatus 2 in maintaining an angular error of approximately 7.5 arc-min at the negative extreme in FIG. 2 and an angular error of approximately 6.0 arc-min at the positive extreme in FIG. 3. - FIG. 6 shows the dimensions of first and
second prisms prisms Prisms input laser beam 20 is incident upon first andsecond prism Dimension Value α (degrees) 15.37° PH 25.40 mm PW 25.40 mm PL 12.23 mm OF 3.00 mm - The wavelength of
input laser beam 20, which is to be circularized, is 257.25 nm in one particular embodiment. Because prism apparatus 2 circularizes elliptical laser beams with a variable transverse and lateral radius, apparatus 2 operates over a range of laser beam cross sections. Apparatus 2 is such that first and second prism mounts 8, 10, respectively, are in a nominal position when the transverse radius of theinput laser beam 20 measures 0.435 mm and the lateral radius measures 0.223 mm.Slide adjustment member 16 may then be adjusted to translateslide 6 to the negative extreme position shown in FIG. 2 to accommodate a laser beam with a minimum transverse radius of 0.348 mm and to the positive extreme position shown in FIG. 3 to accommodate a maximum transverse radius of 0.522 mm, where both beams have a lateral radius of 0.223 mm. These varying transverse radii may be summarized by a scale factor in relation to the nominal radius of 0.435 mm, as shown in the following table. (These dimensions, of course, are only illustrative of one embodiment.)Transverse Radius Lateral Radius Scale Slide (mm) (mm) Factor Position 0.348 0.223 0.8 Negative extreme 0.435 0.223 1.0 Nominal 0.522 0.223 1.2 Positive extreme - The absolute value of change in rotation of PI, which is the angle between
first entrant face 42 and a plane perpendicular to an axis ofinput laser beam 20, is related to the absolute value of translational distance, d, which slide 6 travels by the following: - Δθfirst prism=tan−1(d/L 1)
- where L1 is the length from first
distal pivot 30 to firstproximal pivot 32. Likewise P2, which is the angle betweensecond entrant face 46 and the plane perpendicular to an axis ofinput laser beam 20, is also related to the absolute value of translational distance, d, by the following: - Δθsecond prism=tan−1(d/L 2)
- where L2 is the length from second
distal pivot 38 to secondproximal pivot 40. A third value, L3, is the distance from firstproximal pivot 32 to secondproximal pivot 40. All three values, L1, L2, and L3, are chosen to minimize the angular displacement and changes in transverse displacement, t, ofoutput laser beam 24 over the above range of scale factors. The changes in rotation PI, P2 of first andsecond prisms - The relationship between the laser beam radii (scale factor), the transverse displacement, t, between
input laser beam 20 andoutput laser beam 24,first prism 12 andsecond prism 14 orientation, and the angles of incidence and refraction fromfirst prism 12 and second prism 14 (in degrees) is summarized in the following table.Value by Scale Factor Dimension 0.8 1 1.2 t (mm) 0.2520619 0.2666618 0.2789777 P1 22.800 28.600 31.700 P2 33.491 41.700 46.098 A1 22.800 28.600 31.700 A2 30.304 33.933 35.824 A3 22.307 28.594 31.513 A4 29.991 33.929 35.711 B1 14.934 18.563 20.454 B2 49.354 57.076 61.655 B3 14.621 18.559 20.341 B4 48.733 57.067 61.366 - Although the invention has been described with reference to particular embodiments, the description is only an example of the invention's application and should not be taken as a limitation. In particular, even though much of the preceding discussion is of a prism material of fused silica and a particular laser beam wavelength of 257.25 nm, alternative embodiments of this invention include various other prism materials and laser beam wavelengths. Various other adaptations and combinations of features of the embodiments disclosed are within the scope of the invention as defined by the following claims.
Claims (13)
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
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US09/365,102 US6429982B2 (en) | 1999-07-30 | 1999-07-30 | Counter-rotating anamorphic prism assembly with variable spacing |
PCT/US2000/040461 WO2001009660A2 (en) | 1999-07-30 | 2000-07-24 | Counter-rotating anamorphic prism assembly with variable spacing |
JP2001514616A JP2003506740A (en) | 1999-07-30 | 2000-07-24 | Counter-rotating anamorphic prism assembly with variable spacing |
AU71384/00A AU7138400A (en) | 1999-07-30 | 2000-07-24 | Counter-rotating anamorphic prism assembly with variable spacing |
KR1020017003958A KR20010099657A (en) | 1999-07-30 | 2000-07-24 | Counter-rotating anamorphic prism assembly with variable spacing |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/365,102 US6429982B2 (en) | 1999-07-30 | 1999-07-30 | Counter-rotating anamorphic prism assembly with variable spacing |
Publications (2)
Publication Number | Publication Date |
---|---|
US20010053033A1 true US20010053033A1 (en) | 2001-12-20 |
US6429982B2 US6429982B2 (en) | 2002-08-06 |
Family
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/365,102 Expired - Lifetime US6429982B2 (en) | 1999-07-30 | 1999-07-30 | Counter-rotating anamorphic prism assembly with variable spacing |
Country Status (5)
Country | Link |
---|---|
US (1) | US6429982B2 (en) |
JP (1) | JP2003506740A (en) |
KR (1) | KR20010099657A (en) |
AU (1) | AU7138400A (en) |
WO (1) | WO2001009660A2 (en) |
Cited By (6)
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US20030223132A1 (en) * | 2002-05-13 | 2003-12-04 | Wolfgang Seifert | Method and device for variably attenuating the intensity of a light beam |
US20070008623A1 (en) * | 2005-07-11 | 2007-01-11 | Seiden Harold N | Compact self-compensating beam splitter apparatus and method of using |
US20110199586A1 (en) * | 2010-02-12 | 2011-08-18 | Seiko Epson Corporation | Projector and anamorphic prism optical unit |
CN109061665A (en) * | 2018-08-10 | 2018-12-21 | 江苏亮点光电科技有限公司 | A kind of low fever multi-laser high frequency range-measurement system |
US10215712B2 (en) * | 2009-09-02 | 2019-02-26 | Kla-Tencor Corporation | Method and apparatus for producing and measuring dynamically focused, steered, and shaped oblique laser illumination for spinning wafer inspection system |
US20190258067A1 (en) * | 2018-02-21 | 2019-08-22 | Ricoh Company, Ltd. | Light illumination device, light processing apparatus using light illumination device, light illumination method, and light processing method |
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DE50210560D1 (en) * | 2001-11-06 | 2007-09-06 | Raylase Ag | Method and device for controlling the laser beam energy of two Brewster elements rotating in an opposite direction |
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WO2009002544A1 (en) * | 2007-06-26 | 2008-12-31 | Rolls-Royce Corporation | Prism mount for a laser deposition device |
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- 1999-07-30 US US09/365,102 patent/US6429982B2/en not_active Expired - Lifetime
-
2000
- 2000-07-24 KR KR1020017003958A patent/KR20010099657A/en not_active Application Discontinuation
- 2000-07-24 JP JP2001514616A patent/JP2003506740A/en not_active Withdrawn
- 2000-07-24 AU AU71384/00A patent/AU7138400A/en not_active Abandoned
- 2000-07-24 WO PCT/US2000/040461 patent/WO2001009660A2/en active Application Filing
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030223132A1 (en) * | 2002-05-13 | 2003-12-04 | Wolfgang Seifert | Method and device for variably attenuating the intensity of a light beam |
US20070008623A1 (en) * | 2005-07-11 | 2007-01-11 | Seiden Harold N | Compact self-compensating beam splitter apparatus and method of using |
US7352512B2 (en) * | 2005-07-11 | 2008-04-01 | The Boeing Company | Compact self-compensating beam splitter apparatus and method of using |
US10215712B2 (en) * | 2009-09-02 | 2019-02-26 | Kla-Tencor Corporation | Method and apparatus for producing and measuring dynamically focused, steered, and shaped oblique laser illumination for spinning wafer inspection system |
US20110199586A1 (en) * | 2010-02-12 | 2011-08-18 | Seiko Epson Corporation | Projector and anamorphic prism optical unit |
US8827463B2 (en) * | 2010-02-12 | 2014-09-09 | Seiko Epson Corporation | Projector and anamorphic prism optical unit |
US20190258067A1 (en) * | 2018-02-21 | 2019-08-22 | Ricoh Company, Ltd. | Light illumination device, light processing apparatus using light illumination device, light illumination method, and light processing method |
US10942357B2 (en) * | 2018-02-21 | 2021-03-09 | Ricoh Company, Ltd. | Light illumination device, light processing apparatus using light illumination device, light illumination method, and light processing method |
CN109061665A (en) * | 2018-08-10 | 2018-12-21 | 江苏亮点光电科技有限公司 | A kind of low fever multi-laser high frequency range-measurement system |
Also Published As
Publication number | Publication date |
---|---|
AU7138400A (en) | 2001-02-19 |
WO2001009660A3 (en) | 2001-11-08 |
US6429982B2 (en) | 2002-08-06 |
WO2001009660A2 (en) | 2001-02-08 |
KR20010099657A (en) | 2001-11-09 |
JP2003506740A (en) | 2003-02-18 |
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