JP2006301234A - Uniformizing optical device and parallel light source apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical device for equalizing and uniformizing intensity distribution in the plane of parallel light, and to provide a parallel light source apparatus using the optical device. <P>SOLUTION: The uniformizing optical device 40 has uniformizig elements 41<SB>2</SB>and 41<SB>2</SB>. The configuration of the uniformizing elements 41<SB>1</SB>and 41<SB>2</SB>is such that, where the direction in which incident light runs is Z direction and directions perpendicular to the Z direction and perpendicular to each other are X direction and Y direction, an incident face 44 and an emission face 45 which are perpendicular to the Z direction are provided. Additionally, two total reflection mirrors 42<SB>1</SB>and 42<SB>2</SB>are disposed apart from and parallel to each other at 45° relative to an X-Y plane and a Y-Z plane. Further, one or more semitransparent mirrors 43<SB>1</SB>to 43<SB>3</SB>are disposed between the total reflection mirrors 42<SB>1</SB>and 42<SB>2</SB>and between the incident face 44 and emission face 45 at predetermined intervals so as to be parallel to the total reflection mirrors 42<SB>1</SB>and 42<SB>2</SB>. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a uniformizing optical device and a parallel light source device using the same, and more particularly to a uniformizing optical device for obtaining parallel light having a uniform in-plane intensity distribution and a parallel light source device using the same. .

  Conventionally, for example, a laser light source for semiconductor exposure has a high-output and large-diameter optical fiber bundle output structure in which pigtail modules are bundled, and is used as a light source for a maskless exposure machine using a DMD (Digital Micromirror Device). Yes. When the light from the light source is introduced into the DMD, the more the light beam is parallel, the higher the irradiation efficiency (total utilization efficiency) on the exposure surface. To produce ideal parallel light, the optical fiber bundle output It is necessary to make the end beam spot as close to zero as possible. While the optical fiber bundle output structure type light source has high output, the beam spot size is large (for example, 600 μm), and it is difficult to extract the light as parallel light. is there. Since there is a limit to increasing the use efficiency of the optical system, it is currently necessary to rely on the high output of each semiconductor laser used in the pigtail module.

  Further, in the exposure control, it is necessary to average the in-plane intensity distribution. For example, in the case of an optical fiber bundle module, the output of the central portion of the illumination area is high, and the light intensity tends to decrease as the distance from the center increases. Since the low intensity portion cannot contribute to the exposure, the effective area is limited. Even within the effective range, since exposure control is performed in accordance with a location where the in-plane strength is low, it is necessary to match a high strength portion with a low portion, resulting in a problem that the output is lowered.

  The present invention has been made in view of such problems of the prior art, and an object thereof is an optical device that averages and equalizes the in-plane intensity distribution of parallel light, and a parallel light source device using the same. Therefore, it is possible to provide a parallel light source device that can be used for a projection device, a projection exposure device, a maskless exposure device, etc., has a high uniformity of in-plane intensity distribution, high parallelism, and high light use efficiency. .

  The homogenizing optical apparatus of the present invention that achieves the above object is orthogonal to the Z direction when the direction in which incident light travels is the Z direction, and the directions orthogonal to the Z direction and orthogonal to each other are the X and Y directions. The two total reflection mirrors are arranged apart from each other in parallel so as to form an angle of 45 ° with respect to the XY plane and the YZ plane. And a uniformizing element comprising one or a plurality of semi-transmissive mirrors arranged in parallel to the total reflection mirror at a predetermined interval between the incident surface and the emission surface between the total reflection mirrors of the surface. It is characterized by.

  Further, a second homogenizing element can be provided on the exit surface side of the homogenizing element. In the second uniformizing element, two total reflection mirrors are arranged in parallel with each other so as to form an angle of 45 ° with respect to the XY plane and the YZ plane. One or a plurality of semi-transmissive mirrors are arranged in parallel with the total reflection mirror at a predetermined interval between the incident surface and the exit surface. .

  Such a homogenizing optical device of the present invention can be arranged as in the following (1) to (6) to constitute a parallel light source device of the present invention.

  (1) It is composed of a lens array of densely arranged positive lenses and a polarization-maintaining single-mode optical fiber in which an exit end is arranged at each focal point of the positive lens, and an incident end of each polarization-maintaining single-mode optical fiber. Including two optical fiber collimator arrays in which polarized light is coupled to each other and the polarization directions of the emission ends thereof are all directed in the same direction, and the parallel light emitted from one optical fiber collimator array and the other optical fiber collimator array The parallel light emitted from the parallel light source is selected so that the polarization directions thereof are orthogonal to each other, and the parallel light is configured to be synthesized by the polarization synthesizer. The parallel light source device of the invention can be configured.

  (2) It consists of a lens array of positive lenses arranged densely and a polarization-maintaining single-mode optical fiber in which an exit end is arranged at each focal point of the positive lens, and the incident end of each polarization-maintaining single-mode optical fiber And the parallel light and the second light emitted from the first optical fiber collimator array therein, including four optical fiber collimator arrays in which the polarized light is coupled to each other and the polarization directions of the emission ends thereof are all directed in the same direction. A third optical fiber collimator array comprising a first polarization synthesizer that is selected such that the polarization directions of the parallel lights emitted from the fiber collimator array are orthogonal to each other, and combines the parallel lights into the first combined parallel light; Are selected so that the polarization directions of the parallel light emitted from the fourth optical fiber collimator array and the parallel light emitted from the fourth optical fiber collimator array are orthogonal to each other. A second polarization synthesizer configured as parallel light; a part of the first composite parallel light is transmitted; a part of the second composite parallel light is reflected; A non-polarization synthesizer that reflects the remaining part of the first synthesized parallel light and transmits the remaining part of the second synthesized parallel light to synthesize both parallel lights into a fourth synthesized parallel light. The parallel light source device of the present invention is arranged on a parallel light emitting side of a parallel light source device including a deflecting unit that makes the third composite parallel light and the fourth composite parallel light adjacent to each other parallel light traveling in the same direction. Can be configured.

  (3) A positive lens and a light source at the focal point of the positive lens, including two optical collimators in which linearly polarized light is incident on the positive lens from the light source, and parallel light emitted from one optical collimator and the other The parallel light beams emitted from the optical collimator are arranged so that the polarization directions of the parallel light beams are orthogonal to each other, and the parallel light beams are combined by a polarization beam combiner. The one optical collimator and the other optical collimator are The parallel light source device of the present invention can be configured by arranging the parallel light source devices on the parallel light exit side of the parallel light source devices that are shifted from each other.

  (4) A parallel lens that includes a positive lens and four optical collimators that have a light source at the focal point of the positive lens and in which linearly polarized light enters the positive lens from the light source, and is emitted from the first optical collimator therein. A first polarization synthesizer which is arranged so that the polarization directions of the light and the parallel light emitted from the second light collimator are orthogonal to each other, and synthesizes the parallel light into the first combined parallel light; A second polarization synthesizer that is arranged so that the polarization directions of the parallel light emitted from the collimator and the parallel light emitted from the fourth light collimator are orthogonal to each other, and synthesizes both parallel lights into a second synthesized parallel light. And transmitting a part of the first combined parallel light and reflecting a part of the second combined parallel light to combine both parallel lights into a third combined parallel light, and the rest of the first combined parallel light Part of the light is reflected and the remaining part of the second synthesized parallel light is transmitted. And a non-polarization combiner that combines the two parallel lights into a fourth combined parallel light, and deflecting means for converting the third combined parallel light and the fourth combined parallel light into parallel light that advances adjacently in the same direction. The first optical collimator and the second optical collimator are displaced from each other, and the third optical collimator and the fourth optical collimator are disposed on the parallel light emitting side of the parallel light source device. The parallel light source device of the present invention can be configured.

  (5) A lens array of positive lenses arranged densely, and two optical collimator arrays each having a light source at each focal point of the positive lens and into which light whose polarization directions are all in the same direction are incident. The parallel light emitted from one optical collimator array and the parallel light emitted from the other optical collimator array are arranged so that the polarization directions thereof are orthogonal to each other, and the parallel light is synthesized by the polarization synthesizer. The parallel light source device of the present invention can be configured by being arranged on the parallel light emitting side of the parallel light source device thus configured.

  (6) A lens array of positive lenses arranged densely, and four optical collimator arrays each having a light source at each focal point of the positive lens and into which light whose polarization directions are all in the same direction are incident. The parallel light emitted from the first light collimator array and the parallel light emitted from the second light collimator array are arranged so that the polarization directions of the parallel light are orthogonal to each other. The first polarization synthesizer for parallel light is provided, and the parallel light emitted from the third optical collimator array and the parallel polarization direction emitted from the fourth optical collimator array are arranged so as to be orthogonal to each other. A second polarization synthesizer that synthesizes the light into a second synthesized parallel light; synthesizes both parallel lights by transmitting a part of the first synthesized parallel light and reflecting a part of the second synthesized parallel light; The third combined parallel light A non-polarization synthesizer that reflects the remaining part of the first synthesized parallel light and transmits the remaining part of the second synthesized parallel light to synthesize both parallel lights into a fourth synthesized parallel light; The parallel light source device of the present invention is configured by arranging the third composite parallel light and the fourth composite parallel light adjacent to each other on the parallel light exit side of the parallel light source device including a deflecting unit that makes parallel light traveling in the same direction. be able to.

  According to the homogenizing optical device of the present invention, even if the in-plane intensity distribution of incident parallel light is non-uniform, it can be emitted as averaged and uniform parallel light. By disposing the uniformizing optical device on the parallel light emission side of the parallel light source device, a device suitable for an illumination light source device such as a projection device, a projection exposure device, a maskless exposure device, or the like can be obtained. For example, when used as a light source for a maskless exposure machine using DMD, the exposure time can be shortened.

  Hereinafter, the uniformizing optical device of the present invention and a parallel light source device using the same will be described based on examples.

  First, an embodiment of a parallel light source device to which the uniformizing optical device of the present invention can be applied will be described with reference to FIGS.

  FIG. 1 is a cross-sectional view showing a configuration of a parallel light source device according to one embodiment to which the homogenizing optical device of the present invention can be applied. The parallel light source device includes first to fourth optical fiber collimator arrays 11 to 14, a first polarization that combines the parallel light from the first optical fiber collimator array 11 and the parallel light from the second optical fiber collimator array 12. The light is synthesized by the combiner 15, the second polarization combiner 16 that combines the parallel light from the third optical fiber collimator array 13 and the parallel light from the fourth optical fiber collimator array 14, and the first polarization combiner 15. A non-polarization combiner 17 that combines the first combined parallel light 19 and the second combined parallel light 20 combined by the second polarization combiner 16 into a third combined parallel light 21 and a fourth combined parallel light 22; It comprises a reflecting prism 18 that directs the fourth synthesized parallel light 22 synthesized by the non-polarization synthesizer 17 in the same direction as the third synthesized parallel light 21.

  Here, since the first to fourth optical fiber collimator arrays 11 to 14 have the same configuration, the configuration will be described with the optical fiber collimator array 11 as a representative. The optical fiber collimator array 11 includes a lens array 10 in which a plurality of minute positive lenses 1 having the same characteristics as shown in a plan view in FIG. 2 are densely arranged in an array, and focal positions on the optical axis of the positive lens 1. Each of the polarization-maintaining single-mode optical fibers 2 arranged in correspondence to the individual positive lenses 1 of the lens array 10. At the incident end of the fiber 2, as shown in FIG. 3, the oscillation light having the polarization plane 5 in the direction of the double arrow from the semiconductor laser 3 having the same characteristics is one polarization plane of the polarization-maintaining single-mode optical fiber 2. They are coupled via the condenser lens 4 so as to be incident coupled in accordance with the storage direction.

  Here, the shape and arrangement direction of the positive lens 1 of the lens array 10 of the optical fiber collimator array 11 will be described for future explanation. As shown in FIG. 2, when the positive lens 1 is to be densely arranged, the outer shape thereof is preferably a regular hexagon centered on the optical axis. When the direction in which the positive lenses 1 are arranged in a row is the X direction and the direction orthogonal thereto is the Y direction, the row of the positive lenses 1 arranged in a row in the X direction and the row of the adjacent positive lenses 1 adjacent in the Y direction are: The repetition pitch of the positive lens 1 is shifted by half.

  Returning to FIG. 1, the Y directions of the lens arrays 10 of the first to fourth optical fiber collimator arrays 11 to 14 are all perpendicular to the plane of FIG. In any lens array 10, the positive lenses 1 are arranged in a row in parallel to the plane of FIG.

  In each of the first to fourth optical fiber collimator arrays 11 to 14, the polarization direction of the light emitted from the exit end of each polarization-maintaining single-mode optical fiber 2 of the lens array 10 depends on each optical fiber collimator array. As shown in FIG. 1, the first fiber collimator array 11 is p-polarized light, the second fiber collimator array 12 is s-polarized light, and the third fiber collimator array 13 is Are arranged to be p-polarized light and s-polarized light in the fourth fiber collimator array 14.

  With such a configuration, in each of the first to fourth optical fiber collimator arrays 11 to 14, p-polarized light or s-polarized light is emitted from the exit end of each of the polarization-maintaining single-mode optical fibers 2 arranged in an array. In the single mode, divergent light having a Gaussian intensity is emitted, and each divergent light is converted into parallel light by the corresponding positive lens 1 of the lens array 10. Since parallel light in the same direction (optical axis direction) is emitted from any of the adjacent positive lenses 1 of the lens array 10, p-polarized parallel light as a whole is secondly emitted from the first fiber collimator array 11. The fiber collimator array 12 emits s-polarized parallel light as a whole, the third fiber collimator array 13 emits p-polarized parallel light as a whole, and the fourth fiber collimator array 14 emits s-polarized parallel light as a whole. The

  Then, the p-polarized parallel light from the first optical fiber collimator array 11 and the s-polarized parallel light from the second optical fiber collimator array 12 travel in directions orthogonal to each other as shown in the figure, and the third fiber The p-polarized parallel light from the collimator array 13 and the s-polarized parallel light from the fourth fiber collimator array 14 are in directions orthogonal to each other so as to proceed in directions orthogonal to each other as shown in the figure. The lens array 10 of the first optical fiber collimator array 11 and the lens array 10 of the fourth optical fiber collimator array 14 are substantially in the same plane, the lens array 10 of the second optical fiber collimator array 12, The lens arrays 10 of the three optical fiber collimator array 13 are arranged so as to be located on substantially the same plane.

  A first polarization synthesizer 15 is disposed at a position where the p-polarized parallel light from the first optical fiber collimator array 11 and the s-polarized parallel light from the second optical fiber collimator array 12 are orthogonal to each other, and a third optical fiber collimator. A second polarization synthesizer 16 is disposed at a position where the p-polarized parallel light from the array 13 and the s-polarized parallel light from the fourth optical fiber collimator array 14 are orthogonal to each other. Like the polarization beam splitter prism, the first polarization synthesizer 15 and the second polarization synthesizer 16 transmit substantially 100% of the p-polarized light and approximately 100 of the s-polarized light through the polarization composition surfaces A and B arranged at 45 °. % Reflection characteristics. Therefore, the p-polarized parallel light from the first optical fiber collimator array 11 is transmitted through the polarization combining surface A of the first polarization synthesizer 15, and the s-polarized parallel light from the second optical fiber collimator array 12 is combined in the polarization. The parallel light reflected by the surface A is combined on the polarization combining surface A of the first polarization synthesizer 15 to become the first combined parallel light 19. Further, the p-polarized parallel light from the third optical fiber collimator array 13 is transmitted through the polarization combining surface B of the second polarization synthesizer 16, and the s-polarized parallel light from the fourth optical fiber collimator array 14 is combined in its polarization. The parallel light reflected by the surface B is combined by the polarization combining surface B of the second polarization synthesizer 16 to become the second combined parallel light 20.

  A non-polarization synthesizer 17 is disposed at a position where the first combined parallel light 19 and the second combined parallel light 20 are orthogonal to each other. The non-polarization synthesizer 17 depends on the polarization state of the first combined parallel light 19 and the second combined parallel light 20 on its non-polarization combining surface C arranged at 45 °, like a normal beam splitter prism or half mirror. Without reflecting, approximately 50% of the intensity is reflected, and the remaining approximately 50% of the intensity is transmitted. Therefore, almost half the intensity of the first synthesized parallel light 19 is reflected by the non-polarized synthetic surface C. Then, approximately half the intensity of the second combined parallel light 20 is transmitted through the non-polarized light combining surface C, and these parallel lights are combined into the third combined parallel light 21. Further, substantially half the intensity of the first synthesized parallel light 19 is transmitted through the non-polarized synthetic surface C, and almost half the intensity of the second synthesized parallel light 20 is reflected by the non-polarized synthetic surface C, and these parallel lights are synthesized. Then, the light is reflected by the reflecting surface D of the reflecting prism 18 in the same direction as the third synthesized parallel light 21 to become the fourth synthesized parallel light 22. Since the 3rd synthetic | combination parallel light 21 and the 4th synthetic | combination parallel light 22 adjoin with the same intensity | strength in the same direction without gap, the 3rd synthetic | combination parallel light 21 and the 4th synthetic | combination parallel light 22 are match | combined, and parallelism with high parallelism is high. The light can be used as illumination light for a projection apparatus, a projection exposure apparatus, a maskless exposure apparatus, or the like. In addition, since the light reflected or transmitted by the first polarization synthesizer 15, the second polarization synthesizer 16, and the non-polarization synthesizer 17 is finally used as a parallel light component, the light use efficiency is extremely high. It has become a thing. In addition, since the light source disposed at the focal point of the positive lens 1 is the exit end of the polarization-maintaining single-mode optical fiber 2, the light source is substantially a point light source, so that the combined parallel light 19, 20, 21, 22 The parallelism is extremely high.

  By the way, the first combined parallel light 19, the second combined parallel light 20, and the parallel combined parallel light of the third combined parallel light 21 and the fourth combined parallel light 22 obtained in this way are in-plane intensity. Is uniform, and only the combined parallel lights 19 and 20 can be used as illumination light for a projection apparatus, a projection exposure apparatus, a maskless exposure apparatus, or the like. However, as described above, since the intensity distribution of the light emitted from the exit end of each polarization-maintaining single mode optical fiber 2 has a Gaussian distribution, the NA (numerical aperture) of the positive lens 1 of the lens array 10 And the polarization-maintaining single-mode optical fiber 2 together, the parallel light emitted from the lens array 10 has a Gaussian distribution peak at the center of each positive lens 1. Intensity becomes weaker toward the periphery, and the entire surface of the lens array 10 is parallel light of intensity distribution in which the Gaussian distribution corresponding to the arrangement of the positive lenses 1 is periodically repeated. Therefore, the intensity distribution is not necessarily locally. It cannot be said to be uniform.

  Therefore, when the parallel light from the first optical fiber collimator array 11 and the parallel light from the second optical fiber collimator array 12 are combined by the first polarization combiner 15 (polarization combining surface A), and the second polarization combination. When the parallel light from the third optical fiber collimator array 13 and the parallel light from the fourth optical fiber collimator array 14 are combined by the device 16 (polarization combining surface B), at least one of the two orthogonal directions; For example, the intensity distribution is averaged in the X direction so as to be substantially uniform, and then the two directions orthogonal to each other when the non-polarization combiner 17 combines the first combined parallel light 19 and the second combined parallel light 20. The intensity distribution can be averaged in another direction, for example, the Y direction, so as to be substantially uniform throughout the surface. A configuration for this will be described below.

FIG. 4 is a diagram illustrating the positional relationship between the lens arrays 10 and the intensity distribution of the combined light with respect to the parallel light combined by the first polarization combiner 15 and the second polarization combiner 16, respectively. Hereinafter, the lens arrays 10 of the _first to _fourth optical fiber collimator arrays 11 to 14 are set to 10 ₁ to 10 ₄ , respectively.

When the positive lenses 1 are densely arranged in an array as shown in FIG. 2, if the arrangement pitch of the positive lenses 1 in the X direction is 2M, the arrangement pitch in the Y direction is (3/2) L. And L have a relationship of M = (√3 / 2) L. Here, L corresponds to the length of one side of the regular hexagon of the positive lens 1. In the arrangement shown in FIG. 2, the lens array 10 ₁ (10 ₃ ) and the second optical fiber collimator array 12 (fourth optical fiber collimator array 14) of the first optical fiber collimator array 11 (third optical fiber collimator array 13). ) Lens array 10 ₂ (10 ₄ ), the first polarization synthesizer 15 (second polarization synthesizer 16) so that a displacement of 1/2 of the lens arrangement pitch in the X direction, that is, M displacement occurs. ), The first optical fiber collimator array 11 (third optical fiber collimator array 13) and the second optical fiber collimator array 12 (fourth optical fiber collimator array 14) are combined. As shown, the light intensity distribution in the X direction of the first combined parallel light 19 (second combined parallel light 20) is substantially uniform. More specifically, when the NA of the positive lens 1 and the NA of the polarization-maintaining single-mode optical fiber 2 are substantially matched, the variation in the light intensity distribution in the X direction connecting the centers of the positive lens 1 is about 2%. is there.

  However, the light intensity distribution in the Y direction of the first combined parallel light 19 (second combined parallel light 20) changes at the same pitch as the arrangement pitch in the Y direction as shown by the distribution curve on the left side of FIG. The repetitive distribution has a peak corresponding to the center position of the positive lens 1.

Next, in FIG. 5, lens arrays 10 ₁ to 10 for the parallel light obtained by combining the first combined parallel light 19 and the second combined parallel light 20 averaged in the X direction in this way by the non-polarization combiner 17. ₄ Shows the mutual positional relationship and the intensity distribution of the combined light. Between the lens array 10 and _second lens array 10 ₁ and the second optical fiber collimator array 12 of the first optical fiber collimator array 11, and a lens array 10 ₃ of the third optical fiber collimator array 13 fourth optical fiber collimator array As described above, there is a displacement of M that is half the lens arrangement pitch in the X direction between the 14 lens arrays 10 ₄ , but in the Y direction, the arrangement pitch is (3/2) L in the Y direction. Synthesis is performed so that the lens array 10 ₁ (10 ₂ ) and the lens array 10 ₃ (10 ₄ ) are shifted by half, that is, (3/4) L. In the case of FIG. 5, the phase shift of the repetitive pitch in the X direction of the combination of the lens arrays 10 ₃ and 10 ₄ with respect to the combination of the lens arrays 10 ₁ and 10 ₂ is 1/3 of the lens arrangement pitch 2M in the X direction. That is, the combination of the lens arrays 10 ₁ and 10 ₂ (first combined parallel light 19) and the combination of the lens arrays 10 ₃ and 10 ₄ (second combined parallel light 20) so as to be (2/3) M. To be synthesized. In this case, the variation in the light intensity distribution in the X direction connecting the centers of the positive lenses 1 shows a distribution curve in the upper part of FIG. 5 and is approximately 2% in the above specific example. The intensity distribution is averaged and becomes substantially uniform as shown by a distribution curve on the left side of FIG. Here, the shift amount in the X direction of the combination of the lens arrays 10 ₃ and 10 ₄ with respect to the combination of the lens arrays 10 ₁ and 10 ₂ is on the horizontal axis, and the variation ΔP / P _max in the in-plane light intensity distribution is on the vertical axis. As can be seen from FIG. 7, in the above specific example, the variation in the in-plane light intensity distribution is approximately 6.5%. Note that ΔP is ΔP = P _max −P _min where the maximum value of the light intensity distribution is P _max and the minimum value is P _min .

Instead of FIG. 5, as shown in FIG. 6, the phase shift of the repetitive pitch in the X direction of the combination of the lens arrays 10 ₃ and 10 ₄ with respect to the combination of the lens arrays 10 ₁ and 10 ₂ is expressed as the lens arrangement pitch in the X direction. The combination of the lens arrays 10 ₁ and 10 ₂ (first combined parallel light 19) and the combination of the lens arrays 10 ₃ and 10 ₄ (second combination) so as to be 1/4 of 2M, that is, (1/2) M. You may make it synthesize | combine with the parallel light 20). In this case, the variation in the light intensity distribution in the X direction connecting the centers of the positive lenses 1 shows a distribution curve in the upper part of FIG. 6, and is approximately 2% in the above specific example. The intensity distribution is averaged and becomes substantially uniform as shown by a distribution curve on the left side of FIG. In the above specific example, it can be seen from FIG. 7 that the variation in the in-plane light intensity distribution is about 7.5%, and the variation is slightly larger than the arrangement of FIG. It can be said that. Other arrangement relationships are the same as those in FIG.

Note that the shift amount in the X direction of the combination of the lens arrays 10 ₃ and 10 ₄ with respect to the combination of the lens arrays 10 ₁ and 10 ₂ is 1/6 of the lens arrangement pitch 2M in the X direction, that is, (1/3) M. In the case, as in the case of 1/3, that is, (2/3) M, the variation of the in-plane light intensity distribution is approximately 6.5%, and 1/8, 3/8, that is, (1 In the case of / 4) M and (3/4) M, the variation in the in-plane light intensity distribution is about 7.5%, as in the case of 1/4, that is, (1/2) M. Can be seen from FIG.

From this, the shift amount in the X direction of the combination of the lens arrays 10 ₃ and 10 ₄ with respect to the combination of the lens arrays 10 ₁ and 10 ₂ is in the range of (1/4) M to (3/4) M. It can be seen that the variation in the in-plane light intensity distribution is approximately 7.5% or less. The same applies to the range of (5/4) M to (7/4) M because of the symmetry of the figure.

  Next, FIG. 8 is a cross-sectional view showing a configuration of a modification of the parallel light source device of FIG. A difference from the embodiment of FIG. 1 is that instead of the first polarization synthesizer 15 and the second polarization synthesizer 16, a single polarization synthesizer having a similar configuration in which the size in the cross section of the figure is approximately twice the vertical and horizontal directions. 25 is used, and instead of the reflecting prism 18 and the non-polarization synthesizer 17, a single non-polarization synthesizer 26 having a different shape and a different arrangement of reflection surfaces is used. Explaining this modified example, similarly to the case of FIG. 1, first to fourth optical fiber collimator arrays 11 to 14 are provided, and the configuration of each of the optical fiber collimator arrays 11 to 14 is the same as that of FIG. 1. However, the first optical fiber collimator array 11 and the third optical fiber collimator array 13 are adjacent to each other in the plane of FIG. 8 and their p-polarized parallel light beams are also adjacent to each other and are emitted in the same direction. In addition, the second optical fiber collimator array 12 and the fourth optical fiber collimator array 14 are adjacent to each other in the plane of FIG. 8, and their s-polarized parallel light beams are adjacent to each other and emitted in the same direction. In addition, the p-polarized parallel light from the first optical fiber collimator array 11 and the third optical fiber collimator array 13, the second optical fiber collimator array 12 and the first optical fiber collimator array 12 The s-polarized light from the optical fiber collimator array 14 and the parallel light, to advance in a direction orthogonal to each other as shown, first to fourth optical fiber collimator array 11 to 14 are arranged. The lens array 10 of the first optical fiber collimator array 11 and the lens array 10 of the third optical fiber collimator array 13 are adjacent on the same plane, and the lens array 10 of the second optical fiber collimator array 12 The fourth optical fiber collimator array 14 and the lens array 10 are arranged so as to be adjacent on the same plane.

  Then, the p-polarized parallel light from the first optical fiber collimator array 11 and the third optical fiber collimator array 13 and the s-polarized parallel light from the second optical fiber collimator array 12 and the fourth optical fiber collimator array 14 are obtained. A polarization beam combiner 25 is arranged at a position orthogonal to the polarization beam combining surface E so as to form an angle of 45 ° with the parallel light.

  Therefore, the p-polarized parallel light from the first optical fiber collimator array 11 is transmitted through one side of the polarization combining surface E of the polarization combiner 25, and the s-polarized parallel light from the second optical fiber collimator array 12 is the polarization combining surface. E is reflected on the same one side of E, and both parallel lights are combined on one side of the polarization combining surface E to become the first combined parallel light 19. The p-polarized parallel light from the third optical fiber collimator array 13 is transmitted through one side opposite to the polarization combining surface E of the polarization combiner 25, and the s-polarized parallel light from the fourth optical fiber collimator array 14 is The light is reflected on the same side of the polarization combining surface E, and both parallel lights are combined on one side opposite to the polarization combining surface E to become the second combined parallel light 20.

  As shown in the figure, the first combined parallel light 19 and the second combined parallel light 20 are adjacent to each other and output in parallel, so that the non-polarized light combiner 26 disposed on the exit side has the second combined parallel light. A reflecting surface G that deflects the traveling direction by 90 ° is disposed at a position where the light 20 is incident. Further, a non-polarized light combining surface F similar to the non-polarized light combining surface C is disposed at a position where the first combined parallel light 19 is incident, and the traveling direction of the parallel light reflected by the non-polarized light combining surface F is set to 90. A reflection surface H similar to the reflection surface D that is bent and directed in the same direction as the parallel light incident on the non-polarized light combining surface F is disposed. The reflection surface G, the non-polarization synthesis surface F, and the reflection surface H of the non-polarization synthesizer 26 are arranged in parallel to each other, and it is desirable that these surfaces be integrally arranged in the transparent prism.

  The second synthesized parallel light 20 incident on the reflecting surface G of the non-polarizing synthesizer 26 is deflected by 90 ° and incident on the non-polarizing synthetic surface F, and its intensity of approximately 50% is reflected, and the remaining approximately 50%. The intensity is transparent. Further, the first combined parallel light 19 incident on the non-polarized light combining surface F is also reflected with an intensity of approximately 50% and is transmitted with the remaining intensity of approximately 50%. Accordingly, approximately half the intensity of the first combined parallel light 19 is transmitted through the non-polarized combining surface F, and approximately half the intensity of the second combined parallel light 20 is reflected, and these parallel lights are combined to be combined into the fourth combined parallel. The light 22 is emitted from the non-polarization synthesizer 26. In addition, approximately half the intensity of the first combined parallel light 19 is reflected by the non-polarized combining surface F, approximately half the intensity of the second combined parallel light 20 is transmitted, and these parallel lights are combined. The third combined parallel light 21 is reflected in the same direction as the third combined parallel light 21. Since the 3rd synthetic | combination parallel light 21 and the 4th synthetic | combination parallel light 22 adjoin with the same intensity | strength in the same direction without gap, the 3rd synthetic | combination parallel light 21 and the 4th synthetic | combination parallel light 22 are match | combined, and parallelism with high parallelism is high. The light can be used as illumination light for a projection apparatus, a projection exposure apparatus, a maskless exposure apparatus, or the like. In addition, since the light reflected or transmitted by the polarization synthesizer 25 and the non-polarization synthesizer 26 is finally used as a parallel light component, the light utilization efficiency is extremely high. In addition, since the light source disposed at the focal point of the positive lens 1 is the exit end of the polarization-maintaining single-mode optical fiber 2, the light source is substantially a point light source, so that the combined parallel light 19, 20, 21, 22 The parallelism is extremely high.

Also in this modification, as shown in FIGS. 5 and 6, by adjusting the positional relationship between the lens arrays 10 ₁ to 10 _{4 of the first} to _fourth optical fiber collimator arrays 11 to 14, Parallel light with extremely high parallelism can be obtained in which the intensity distribution is averaged in both the direction and the Y direction and becomes substantially uniform.

The parallel light source device to which the homogenizing optical device of the present invention can be applied has been described based on the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made. For example, instead of disposing the exit end (secondary light source) of the polarization-maintaining single-mode optical fiber 2 at each focal position of the positive lens 1 of the lens arrays 10, 10 ₁ to 10 ₄ , a semiconductor laser that emits linearly polarized light You may make it arrange | position point light sources, such as. Further, regarding the dense arrangement of the positive lenses 1 of the lens arrays 10, 10 ₁ to 10 ₄ , it is shown in FIG. 9A except when the positive lenses 1 having a regular hexagonal outer shape are densely arranged as shown in FIG. In this manner, the square-shaped positive lenses 1 may be densely arranged in a grid pattern, for example, or the circular-shaped positive lenses 1 are stacked in a stack shape as shown in FIG. 9B. You may arrange.

  Next, an embodiment in which the uniformizing optical device of the present invention is applied to the parallel light source device of the above embodiment will be described.

FIG. 10 is a cross-sectional view of an embodiment in which the homogenizing optical device 40 of one embodiment of the present invention is disposed on the parallel light 31 output side of the parallel light source device 30 of the embodiment of FIG. Here, as described in FIG. 1, the parallel light 31 from the parallel light source device 30 is formed by the third composite parallel light 21 and the fourth composite parallel light 22 adjacent to each other without a gap, and in FIG. For ease of explanation, the light beam 31 is shown as a single light beam 31 and has a thickness that covers the entire incident surface 44 of the uniformizing element 41 ₁ .

  Here, the coordinates are defined again. As shown in FIG. 10, the direction in which the parallel light 31 from the parallel light source device 30 travels is defined as the Z direction, the direction orthogonal to the in-plane direction of FIG. 1 is defined as the X direction, and the direction perpendicular to the paper surface is defined as the Y direction.

The homogenizing optical device 40 of this embodiment is configured by connecting a homogenizing element 41 ₁ and a homogenizing element 41 ₂ having the same configuration in series along the traveling direction of the parallel light 31, and the homogenizing element 41 ₂ is uniform. It is arranged to be rotated (twisted) by 90 ° around the Z axis with respect to the chemical element 41 ₁ . Therefore, from the description of the configuration of the uniformizing element 41 ₁ , the configuration and arrangement of the uniformizing element 41 ₂ become clear.

As is clear from FIG. 10, the homogenizing element 41 ₁ has a normal of 45 ° in the XZ plane with respect to the Z direction between the entrance surface 44 and the exit surface 45 orthogonal to the Z direction. The total reflection mirrors 42 ₁ and 42 ₂ are arranged so as to form an angle and are spaced apart from each other in parallel, between the total reflection mirrors 42 ₁ and 42 ₂ and between the entrance surface 44 and the exit surface 45. A plurality of semi-transmissive mirrors 43 ₁ to 43 ₃ are arranged in parallel with the total reflection mirrors 42 ₁ and 42 ₂ at substantially uniform intervals. Such an arrangement, but are not limited to, Briefly, a plurality of parallel plate and one transparent parallel flat plate having a semitransparent mirror 43 _{1-43 3} each on one side of a transparent plurality of parallel plate It can be manufactured by closely overlapping and fixing (assuming that the parallel plates have the same refractive index), and cutting the laminate with two cut surfaces that form an angle of 45 ° with respect to the laminated surface at both ends. it can. The surfaces that are not provided with the semi-transmissive mirrors 43 ₁ to 43 ₃ exposed outside the laminated body constitute total reflection mirrors 42 ₁ and 42 ₂ as the total reflection surfaces, and the two cut surfaces are the entrance surface 44 and the exit surface. A surface 45 is formed.

When the uniformizing element 41 ₁ having such a configuration is arranged such that the incident surface 44 is perpendicular to the parallel light 31 from the parallel light source device 30, the parallel entering the uniformizing element 41 ₁ from the incident surface 44. light 31 receives the partial transmission and partial reflection at the semi-transmissive mirror 43 _{1-43 3} between the total reflection mirror 42 ₁ and 42 _2, and, at its both sides a total reflection at the total reflection mirror 42 ₁ and 42 ₂ As a result, the optical path is limited in the meantime, and the multiple reflection is repeated between the total reflection mirrors 42 ₁ and 42 ₂ and the semi-transmission mirrors 43 ₁ to 43 ₃ , so that the emission surface 45 is reached. The light that has reached one region is distributed over the entire exit surface 45, and the parallel light 31 that has entered the entrance surface 44 is eventually averaged and made uniform by the exit surface 45.

Therefore, in the case of the example of FIG. 10, even if any one of the semiconductor lasers 3 (FIG. 3) belonging to the first to fourth optical fiber collimator arrays 11 to 14 deteriorates or breaks down, the emission intensity is partially reduced or eliminated. The nonuniformity of the light intensity distribution is averaged in the X direction by the uniformizing element 41 _{1, and the} nonuniformity of the light intensity distribution based on the partial deterioration or failure of the semiconductor laser 3 is from the uniformizing element 41 _1. This is not generated in the output parallel light 51.

In addition, since the input parallel light 31 is averaged in the X direction by the uniformizing element 41 ₁ , the variation in the in-plane light intensity distribution due to the dislocation between the lens arrays as described above is also averaged. It gets smaller or disappears.

However, since the homogenization by the homogenizing element 41 ₁ can be performed only in the X direction, another uniform in the output parallel light 51 from the homogenizing element 41 _{1 in} order to perform the averaging in the Y direction. An element 41 ₂ is arranged. The equalizing element 41 ₂ has the same structure as the equalizing element 41 _1, and 90 ° rotation about the Z-axis with respect to equalizing element 41 ₁ (twisted and) are those which are disposed, This time, it is averaged in the Y direction in the same manner. Therefore, the light reaching one region of the incident surface 44 of the incident-side uniformizing element 41 ₁ is distributed two-dimensionally over the entire exit surface 45 of the emitting-side uniformizing element 41 ₂ . Therefore, the parallel light 31 that has entered the incident surface 44 of the uniformizing element 41 ₁ on the incident side of the uniformizing optical device 40 is two-dimensionally averaged and uniformized from the exit surface 45 of the uniformizing element 41 _{2 on} the emitting side. The output parallel light 61 is emitted.

  Therefore, even if any one of the semiconductor lasers 3 (FIG. 3) belonging to the first to fourth optical fiber collimator arrays 11 to 14 deteriorates or breaks down and the light emission intensity partially decreases or disappears, the light intensity distribution is not improved. Uniformity is averaged by the homogenizing optical device 40 in both the X direction and the Y direction orthogonal to each other. Such nonuniformity of the light intensity distribution due to partial degradation or failure of the semiconductor laser 3 is obtained from the homogenizing optical device 40. This is not generated in the output parallel light 61. Also, the variation in the in-plane light intensity distribution due to the displacement between the lens arrays as described above is averaged and becomes smaller.

Note that the number of the semi-transmission mirrors 43 ₁ to 43 ₃ of the uniformizing elements 41 ₁ and 41 ₂ is preferably as large as possible, but if it is too large, attenuation due to absorption increases. Decide in consideration. Further, the transmittance (1-reflectance) of each of the semi-transmissive mirrors 43 ₁ to 43 ₃ may be within a range of 10 to 90%. Note that the number and transmissivity of the semi-transmission mirrors 43 ₁ to 43 _{3 in} the uniformizing element 41 ₁ that is uniform in the X direction and the uniformizing element 41 ₂ that is uniform in the Y direction are not necessarily the same.

Next, FIG. 11 shows a cross-sectional view of an embodiment in which the same homogenizing optical device 40 as in FIG. 10 is arranged on the parallel light 31 output side of the parallel light source device 30 in FIG. The parallel light 31 from the parallel light source device 30 in this case is also the one in which the third combined parallel light 21 and the fourth combined parallel light 22 are adjacent to each other without any gap, as described with reference to FIG. For ease of explanation, the light beam 31 is shown as a single light beam 31 and has a thickness that covers the entire incident surface 44 of the uniformizing element 41 ₁ .

Also in this case, as in the case of FIG. 10, the parallel light 31 that has entered the incident surface 44 of the uniformizing element 41 ₁ on the incident side of the uniformizing optical device 40 is emitted from the emitting surface 45 of the uniformizing element 41 _{2 on} the emission side. Are output as output parallel light 61 that is two-dimensionally averaged and uniformed.

  Therefore, even in this case, even if any of the semiconductor lasers 3 (FIG. 3) belonging to the first to fourth optical fiber collimator arrays 11 to 14 deteriorates or breaks down, the light intensity is partially reduced or eliminated. The nonuniformity of the intensity distribution is averaged in both the X direction and the Y direction orthogonal to each other by the uniformizing optical device 40, and the nonuniformity of the light intensity distribution based on such partial degradation or failure of the semiconductor laser 3 is made uniform. It does not occur in the output parallel light 61 from the optical device 40. In addition, the variation in the in-plane light intensity distribution caused by the displacement between the lens arrays as described above is also averaged and becomes smaller.

  As described above, the uniformizing optical device of the present invention and the parallel light source device using the same have been described based on the embodiments. However, the present invention is not limited to these embodiments, and various modifications are possible.

It is sectional drawing which shows the structure of the parallel light source device of one Example which can apply the homogenization optical apparatus of this invention. It is a top view of a lens array. It is a typical perspective view for demonstrating the structure by which the semiconductor laser is couple | bonded with the incident end of the polarization-maintaining single mode optical fiber. It is a figure which shows the positional relationship between lens arrays with respect to the parallel light synthesize | combined by each of the 1st polarization | polarized-light combiner, and the 2nd polarization | polarized-light combiner, and the intensity distribution of synthetic | combination light. It is a figure which shows the positional relationship between lens arrays with respect to the parallel light synthesize | combined with the non-polarization synthesizer, and the intensity distribution of synthetic | combination light. It is the same figure which shows the deformation | transformation of FIG. It is a figure which shows the relationship of the shift amount to the X direction of the combination of the other lens array with respect to the combination of one lens array, and the variation in in-plane light intensity distribution. It is sectional drawing which shows the structure of the modification of the parallel light source device of FIG. It is a top view of the modification of a lens array. It is sectional drawing of the Example at the time of arrange | positioning the equalization optical apparatus of 1 Example of this invention to the parallel light source device parallel light output side of FIG. It is sectional drawing of the Example at the time of arrange | positioning the equalization optical apparatus of 1 Example of this invention to the parallel light source device parallel light output side of FIG.

Explanation of symbols

1 ... positive lens 2 ... polarization-maintaining single-mode fiber 3 ... semiconductor laser 4 ... condenser lens 5 ... polarization 10 ... lens array 10 ₁ ... lens array 10 ₂ ... second optical fiber of the first optical fiber collimator array Lens array 10 _{3 of} collimator array Lens array 10 _{4 of} third optical fiber collimator array Lens array 11 of fourth optical fiber collimator array First optical fiber collimator array 12 Second optical fiber collimator array 13 Third light Fiber collimator array 14 ... fourth optical fiber collimator array 15 ... first polarization synthesizer 16 ... second polarization synthesizer 17 ... non-polarization synthesizer 18 ... reflecting prism 19 ... first synthesized parallel light 20 ... second synthesized parallel light 21 ... 3rd synthetic | combination parallel light 22 ... 4th synthetic | combination parallel light 25 ... Polarization synthesizer 26 ... Non-polarization synthesizer 30 ... Parallel light source equipment 31 ... output parallel light 40 ... homogenizing optical system 41 ₁ of collimated light source device, 41 ₂ ... equalizing element 42 _1, 42 ₂ ... total reflecting mirror 43 _1, 43 _2, 43 ₃ ... half mirror 44 ... entrance surface 45 ... Output surface 51 ... Output parallel light 61 from homogenizing element ... Output parallel light A from homogenizing optical device ... Polarization combining surface B ... Polarization combining surface C ... Non-polarization combining surface D ... Reflection surface E ... Polarization combining surface F ... Non-polarized synthetic surface G ... Reflective surface H ... Reflective surface

Claims (8)

When the direction in which incident light travels is the Z direction, and the directions orthogonal to the Z direction and orthogonal to each other are the X direction and the Y direction, the X-Y plane has an entrance surface and an exit surface orthogonal to the Z direction. In addition, two total reflection mirrors are arranged in parallel with each other so as to form an angle of 45 ° with respect to the YZ plane, and between the two total reflection mirrors, the incident surface and the exit surface A homogenizing optical apparatus comprising a homogenizing element comprising one or a plurality of transflective mirrors arranged between surfaces in parallel to the total reflection mirror at a predetermined interval. A second uniformizing element is provided on the exit surface side of the uniformizing element, and the second uniformizing element forms an angle of 45 ° with respect to the XY plane and the YZ plane. Two total reflection mirrors are arranged in parallel with each other, and one or a plurality of semi-transmission mirrors are arranged at a predetermined distance between the two total reflection mirrors and between the entrance surface and the exit surface. 2. The uniformizing optical device according to claim 1, wherein the uniformizing optical device is arranged in parallel with the total reflection mirror. It consists of a lens array of densely arranged positive lenses and a polarization-maintaining single-mode optical fiber having an exit end arranged at each focal point of the positive lens, and polarized at the incident end of each polarization-maintaining single-mode optical fiber. Includes two optical fiber collimator arrays where light is combined and the polarization direction of the exit ends are all in the same direction. 3. The uniform light source according to claim 1, wherein the parallel light beams are selected so that the polarization directions of the parallel light beams are orthogonal to each other and the parallel light beams are combined by the polarization beam combiner. A parallel light source device in which an optical device is arranged. It consists of a lens array of densely arranged positive lenses and a polarization-maintaining single-mode optical fiber with an exit end arranged at each focal point of the positive lens, and polarized at the incident end of each polarization-maintaining single-mode optical fiber. 4 optical fiber collimator arrays in which the light is coupled and the polarization directions of the exit ends thereof are all directed in the same direction, and the parallel light emitted from the first optical fiber collimator array therein and the second optical fiber collimator array The polarization direction of the parallel light emitted from is selected so as to be orthogonal to each other, and includes a first polarization synthesizer that synthesizes both parallel lights into the first synthesized parallel light, and is emitted from the third optical fiber collimator array. The parallel light emitted from the fourth optical fiber collimator array and the parallel light emitted from the fourth optical fiber collimator array are selected to be orthogonal to each other. A second polarization synthesizer that transmits a part of the first synthesized parallel light and reflects a part of the second synthesized parallel light to synthesize both parallel lights into a third synthesized parallel light, A non-polarization synthesizer that reflects the remaining part of the first synthesized parallel light and transmits the remaining part of the second synthesized parallel light to synthesize both parallel lights into a fourth synthesized parallel light; 3. The uniformizing optical device according to claim 1, wherein the uniformizing optical device is disposed on a parallel light emitting side of a parallel light source device including a deflecting unit configured to make the third combined parallel light and the fourth combined parallel light adjacent to each other and travel in the same direction. The parallel light source device characterized by being made. A positive lens and a light source at the focal point of the positive lens, including two optical collimators in which linearly polarized light is incident on the positive lens from the light source, and parallel light emitted from one optical collimator and the other optical collimator Are arranged so that the polarization directions of the parallel light beams emitted from the light beam are orthogonal to each other, and the parallel light beams are combined by the polarization beam combiner, and the one light collimator and the other light collimator are displaced from each other. 3. A parallel light source device comprising: the uniform light optical device according to claim 1 disposed on a parallel light emitting side of the parallel light source device. A positive lens, and a light source at the focal point of the positive lens, including four optical collimators in which linearly polarized light is incident on the positive lens from the light source, the parallel light emitted from the first optical collimator therein and the first collimator The first polarization synthesizer is arranged so that the polarization directions of the parallel lights emitted from the two-light collimator are orthogonal to each other, and the two parallel lights are combined into a first synthesized parallel light, and emitted from the third light collimator. And a second polarization synthesizer that is arranged so that the polarization directions of the parallel light and the parallel light emitted from the fourth light collimator are orthogonal to each other, and synthesizes the parallel light into a second combined parallel light, A part of the first combined parallel light is transmitted and a part of the second combined parallel light is reflected to combine both parallel lights into a third combined parallel light, and the remaining part of the first combined parallel light And the remaining part of the second combined parallel light is transmitted. A non-polarizing synthesizer that synthesizes the parallel light into a fourth composite parallel light, and includes a deflecting unit that makes the third composite parallel light and the fourth composite parallel light adjacent to each other and travels in the same direction. The first light collimator and the second light collimator are displaced from each other, and the third light collimator and the fourth light collimator are displaced from each other on a parallel light emission side of the parallel light source device. A parallel light source device comprising: a uniform optical device. A lens array of densely arranged positive lenses, and two optical collimator arrays each having a light source at each focal point of the positive lens and into which light whose polarization directions are all directed in the same direction are incident. The parallel light emitted from the optical collimator array and the parallel light emitted from the other optical collimator array are arranged so that the polarization directions thereof are orthogonal to each other, and the parallel light is synthesized by the polarization synthesizer. A parallel light source device, wherein the uniformizing optical device according to claim 1 is disposed on a parallel light emission side of the parallel light source device. A lens array of positive lenses arranged densely, and four optical collimator arrays each having a light source at each focal point of the positive lens and into which light whose polarization directions are all directed in the same direction are incident. The parallel light emitted from the first light collimator array and the parallel light emitted from the second light collimator array are arranged so that the polarization directions of the parallel light are orthogonal to each other. Is arranged so that the parallel light emitted from the third optical collimator array and the parallel polarization directions emitted from the fourth optical collimator array are orthogonal to each other, and synthesizes both parallel lights And a second polarization synthesizer for generating a second synthesized parallel light, and a part of the first synthesized parallel light is transmitted and a part of the second synthesized parallel light is reflected to synthesize both parallel lights. 3 synthetic parallel lights, the first A non-polarization combiner that reflects the remaining part of the parallel light and transmits the remaining part of the second combined parallel light to combine the parallel light into a fourth combined parallel light; The uniformizing optical device according to claim 1 or 2, wherein the uniformizing optical device according to claim 1 or 2 is disposed on a parallel light emitting side of a parallel light source device including a deflecting unit that makes the combined parallel light and the fourth combined parallel light adjacent to each other and travels in the same direction. A parallel light source device characterized by comprising:

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