WO2014181539A1

WO2014181539A1 - Optical device

Info

Publication number: WO2014181539A1
Application number: PCT/JP2014/002436
Authority: WO
Inventors: 拓也小松; 嘉高佐藤; 竜也平井
Original assignee: カラーリンク・ジャパン株式会社
Priority date: 2013-05-08
Filing date: 2014-05-08
Publication date: 2014-11-13
Also published as: JP2016136165A

Abstract

The present invention solves the problem of a complicated configuration which results when a movement member for moving optical components is required in an optical device with which spectral noise is reduced by moving the optical components. This optical device is equipped with a diffraction part (42) that diffracts and then emits linearly polarized laser light (L00), and a direction changing part (46) that changes the direction of at least a portion of the +1 order light (L11) and at least a portion of the -1 order light (L12) emitted from the diffraction part, so as to be in a parallel direction, and then emits this light. Furthermore, the optical device is equipped with: an incident-side modulation part that changes the polarization direction of the linearly polarized laser light to multiple directions; a first birefringence part that divides the light (modulated by the incident-side modulation part) in a first direction, thereby emitting first light and second light; an emission-side modulation part that changes the polarization direction of the first light and the second light, emitted from the first birefringence part, to multiple directions; and a second birefringence part that divides the light (modulated by the emission-side modulation part) in a second direction different from the first direction, and emits this light as advancing parallel light.

Description

Optical device

The present invention relates to an optical device.

In an apparatus using laser light as a light source, an optical apparatus that reduces speckle noise by moving an optical component is known (for example, see Patent Document 1).
[Patent Document 1] Japanese translations of PCT publication No. 2004-529375

However, the above-described apparatus has a problem that the configuration is complicated because a moving member for moving the optical component is required.

In the first aspect of the present invention, a diffractive portion that diffracts and emits linearly polarized laser light, and at least part of the + 1st order light and at least part of the −1st order light emitted from the diffractive part are provided. An optical device is provided that includes a direction changing unit that converts the light into a parallel direction and emits the light.

In the second aspect of the present invention, the incident-side modulation unit that modulates the polarization direction of the linearly polarized laser beam in multiple directions, and the light modulated by the incident-side modulation unit are divided into the first direction, and the first A first birefringence unit that emits light and second light, an emission-side modulation unit that modulates polarization directions of the first light and the second light emitted from the first birefringence unit in multiple directions, An optical device is provided that includes a second birefringence unit that divides the light modulated by the emission-side modulation unit in a second direction different from the first direction and emits the light traveling in parallel with each other.

Note that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

1 is an overall configuration diagram of a projector 10 provided with an optical device 24. FIG. 2 is a cross-sectional view of an optical device 24. FIG. 3 is a schematic sectional view of a diffraction grating 42. FIG. 4 is a plan view of a liquid crystal layer 62. FIG. 6 is a photograph of experimental results showing the relationship between polarized light incident on the diffraction grating of the optical device 24 and diffracted light. 3 is an exploded perspective view of the optical device 24. FIG. It is a graph which shows the relationship between the wavelength of the light which injects into a diffraction grating, and the intensity | strength of the 0th-order light which a diffraction grating radiate | emits. It is a figure explaining the dispersion | variation in the light radiate | emitted from the optical apparatus 24. FIG. FIG. 6 is an exploded perspective view of an optical device 124 according to another embodiment. It is sectional drawing explaining the form which changed arrangement | positioning of the

diffraction gratings

42 and 46 with respect to the board |

substrates

40 and 44. FIG. It is sectional drawing explaining the form which changed arrangement | positioning of the

diffraction gratings

42 and 46 with respect to the board |

substrates

diffraction gratings

42 and 46 with respect to the board |

substrates

40 and 44. FIG. It is a figure explaining the orientation direction of the molecule | numerator 64 of the liquid crystal layer 62 of the

diffraction gratings

42 and 46 seen from the incident side. It is a figure explaining the orientation direction of the molecule | numerator 64 of the liquid crystal layer 62 of the

diffraction gratings

42 and 46 seen from the incident side. FIG. 6 is an exploded perspective view of an optical device 224 according to another embodiment. It is a whole block diagram of the optical apparatus 324 which changed a part. It is a whole block diagram of the optical apparatus 424 which changed a part. It is a whole block diagram of the optical apparatus 524 which changed a part. It is the schematic of the experimental apparatus which investigated speckle noise reduction. It is the result of the experiment which proves the reduction of speckle noise. 6 is a perspective view of a diffraction grating 724 in which a part of the diffraction grating 42 is changed. FIG.

Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

FIG. 1 is an overall configuration diagram of the projector 10 provided with the optical device 24. The up and down and front directions indicated by arrows in FIG. The projector 10 generates an image with the laser light emitted from the

laser light sources

12, 14, and 16 and projects the image on the screen 30.

As shown in FIG. 1, the projector 10 includes

laser light sources

12, 14, 16,

dichroic mirrors

18, 20, a MEMS mirror 22, an optical device 24, a projection unit 26, and a control unit 28.

The laser light source 12 emits red light RL that is linearly polarized laser light having a vertical polarization direction toward the MEMS mirror 22. The laser light source 14 emits green light GL, which is linearly polarized laser light having a vertical polarization direction, toward the dichroic mirror 18. The laser light source 16 emits blue light BL, which is linearly polarized laser light having a vertical direction as a polarization direction, toward the dichroic mirror 20.

The

dichroic mirrors

18 and 20 include a dielectric multilayer film as an example. The dichroic mirrors 18 and 20 may be dichroic prisms.

The dichroic mirror 18 is disposed on the path of the green light GL emitted from the laser light source 14. The dichroic mirror 18 reflects the green light GL and transmits light of other wavelengths. Accordingly, the dichroic mirror 18 transmits the red light RL emitted from the laser light source 12. On the other hand, the dichroic mirror 18 reflects the green light GL emitted from the laser light source 14 toward the MEMS mirror 22.

The dichroic mirror 20 is disposed on the path of the blue light BL emitted from the laser light source 16. The dichroic mirror 20 reflects the blue light BL and transmits light of other wavelengths. Accordingly, the dichroic mirror 20 transmits the red light RL emitted from the laser light source 12. The dichroic mirror 20 transmits the green light GL emitted from the laser light source 14 and reflected by the dichroic mirror 18. On the other hand, the dichroic mirror 20 reflects the blue light BL emitted from the laser light source 16 toward the MEMS mirror 22.

The MEMS mirror 22 is disposed on the path of the red light RL emitted from the laser light source 12, the green light GL reflected by the dichroic mirror 18, and the blue light BL reflected by the dichroic mirror 20. The MEMS mirror 22 moves in a two-dimensional plane. The MEMS mirror 22 projects an image on the screen 30 by reflecting light while moving.

The optical device 24 diffracts red light RL, green light GL, and blue light BL, which are linearly polarized light, to reduce speckle noise. Details of the optical device 24 will be described later.

The projection unit 26 enlarges the light that forms an image and is emitted from the optical device 24, and projects the image onto the screen 30.

The control unit 28 performs overall control of the projector 10. An example of the control unit 28 is an arithmetic device such as a CPU (Central Processing Unit). The control unit 28 switches the

laser light sources

12, 14, 16 on and off. The control unit 28 controls the reflection and position of the MEMS mirror 22 to generate an image.

In the projector 10 described above, the control unit 28 turns on one of the

laser light sources

12, 14, and 16 to emit laser light. For example, the control unit 28 turns on the laser light source 12 and emits red light RL. The red light RL passes through the

dichroic mirrors

18 and 20 and reaches the MEMS mirror 22. The control unit 28 controls the reflection and position of the MEMS mirror 22 in correspondence with the red image to be projected. As a result, the MEMS mirror 22 reflects the red light RL toward the optical device 24. The optical device 24 converts the red light RL into a state where speckle noise can be reduced, and emits the red light RL to the projection unit 26. The projection unit 26 magnifies and projects an image composed of the red light RL onto the screen 30. Similarly, the control unit 28 sequentially turns on the

laser light sources

14 and 16 and controls the reflection and position of the MEMS mirror 22 to project an image composed of the green light GL and the blue light BL onto the screen 30. To do. Thereby, the projector 10 can project a color image with reduced speckle noise.

FIG. 2 is a cross-sectional view of the optical device 24. The direction indicated by the arrow in FIG. 2 is the forward direction in which the light L0 incident on the optical device 24 travels. The light L00 incident on the optical device 24 is linearly polarized light whose polarization direction is the vertical direction emitted from the

laser light sources

12, 14, and 16 and reflected by the MEMS mirror 22. The incident linearly polarized light may not be in the vertical direction. In other words, the direction of the optical device 24 can be freely set with respect to the polarization direction of the incident linearly polarized light.

As shown in FIG. 2, the optical device 24 includes a substrate 40, a diffraction grating 42, a substrate 44, a diffraction grating 46, a quarter wavelength plate 48, a substrate 50, a diffraction grating 52, and a substrate 54. , A diffraction grating 56 and a substrate 58. In FIG. 2, the substrate 40 to the substrate 58 are bonded together, but a part or all of the substrate 40 to the substrate 58 may be separated.

An example of the

substrates

40, 44, 50, 54, and 58 is an optically isotropic glass substrate. An example of the

substrates

40, 44, 50, 54, and 58 has a planar shape and a rectangular shape when viewed from the light traveling direction. The thickness of the

substrates

40, 44, 50, 54, 58 is, for example, 0.21 mm. The

substrates

40, 44, 50, 54, and 58 are arranged in this order from the incident side to the outgoing side of the light L00 reflected by the MEMS mirror 22. The

substrates

40, 44, 50, 54, and 58 are disposed substantially perpendicular to the traveling direction of the incident light L00.

An example of the

diffraction gratings

42, 46, 52, and 56 is a liquid crystal polarization diffraction grating in which the alignment direction of liquid crystal molecules periodically changes in a plane. That is, the

diffraction gratings

42, 46, 52, and 56 diffract polarized light based on the polarization state. For example, the

diffraction gratings

42, 46, 52, and 56 increase the intensity of one diffracted light (for example, + 1st order light) based on the polarization state and increase the intensity of the other diffracted light (for example, −1st order light). Reduce strength. The

diffraction gratings

42, 46, 52, and 56 modulate the polarization state. For example, the

diffraction gratings

42, 46, 52, and 56 modulate linearly polarized light into circularly polarized light. The

diffraction gratings

42, 46, 52, and 56 modulate clockwise circularly polarized light into counterclockwise circularly polarized light or counterclockwise circularly polarized light into clockwise circularly polarized light.

The diffraction grating 42 is an example of a diffraction part. The diffraction grating 42 is disposed between the substrate 40 and the substrate 44. In other words, the diffraction grating 42 is disposed on the most light incident side among the

diffraction gratings

42, 46, 52, and 56. The diffraction grating 42 diffracts and emits incident linearly polarized laser light.

The diffraction grating 46 is an example of a direction changing unit. The diffraction grating 46 is disposed between the substrate 44 and the substrate 50 and on the incident side surface of the quarter-wave plate 48. The diffraction grating 46 is disposed on the emission side with respect to the diffraction grating 42. The diffraction grating 46 emits circularly polarized light obtained by converting at least part of the + 1st order light emitted from the diffraction grating 42 and at least part of the −1st order light in parallel directions.

The quarter-wave plate 48 is provided between the substrate 44 and the substrate 50 and on the exit side surface of the diffraction grating 46. The quarter wavelength plate 48 is disposed between the

diffraction gratings

42 and 46 and the

diffraction gratings

52 and 56. The quarter wavelength plate 48 modulates the polarization state of the incident polarized light. For example, the quarter wave plate 48 modulates incident linearly polarized light into circularly polarized light, and modulates incident circularly polarized light into linearly polarized light. Therefore, the quarter wave plate 48 emits the circularly polarized light emitted from the diffraction grating 46 as linearly polarized light.

The diffraction grating 52 is an example of a second diffraction part. The diffraction grating 52 is provided between the substrate 50 and the substrate 54 and on the emission side of the diffraction grating 46 and the quarter wavelength plate 48. The diffraction grating 52 is disposed on the incident side of the diffraction grating 56. The diffraction grating 52 diffracts and emits the linearly polarized light emitted from the quarter-wave plate 48 in a direction different from the diffraction direction of the diffraction grating 42.

The diffraction grating 56 is an example of a second direction conversion unit. The diffraction grating 56 is disposed between the substrate 54 and the substrate 58 and on the emission side of the diffraction grating 52. In other words, the diffraction grating 56 is disposed on the most output side of the

diffraction gratings

42, 46, 52, 56. The diffraction grating 56 converts at least a part of the + 1st order light diffracted by the diffraction grating 52 and at least a part of the −1st order light into circularly polarized light that travels in parallel directions and emits it. Further, the diffraction grating 56 emits the emitted light so that they overlap each other.

FIG. 3 is a schematic cross-sectional view of the diffraction grating 42. FIG. 4 is a plan view of the liquid crystal layer 62. The

diffraction gratings

46, 52, and 56 have the same configuration as the diffraction grating 42. As shown in FIG. 3, the diffraction grating 42 includes an alignment layer 60 formed on the substrate 40 and a liquid crystal layer 62 formed on the alignment layer 60. The alignment of the molecules 64 of the liquid crystal layer 62 arranged in the normal direction of the substrate 40 is in the same direction. FIG. 4 shows the alignment direction of the molecules 64 of the liquid crystal layer 62 in the same layer, that is, in the same layer from the substrate 40. As shown in FIG. 4, the orientation of the molecules 64 of the liquid crystal layer 62 changes gradually and periodically in a plane, that is, in the same layer. Here, the direction in which the molecules 64 having the same orientation are arranged in a plan view as viewed from the normal direction of the substrate 40 is a direction in which the stripe extends. Further, in the plan view, the direction in which the orientation of the molecules 64 changes is defined as the direction of the stripe periodicity. Therefore, the direction in which the stripe extends is orthogonal to the direction of the periodicity of the stripe. Thereby, the liquid crystal layer 62 diffracts the incident polarized light. The diffracted light, for example, the 0th order light and the ± 1st order light are arranged along the direction of the periodicity of the stripe. The diffraction grating 42 shown in FIGS. 3 and 4 is manufactured by irradiating the liquid crystal layer 62 with different polarized light, for example, clockwise circularly polarized light and counterclockwise circularly polarized light from different directions and aligning them with a holography device or the like. be able to. Thereby, the diffraction grating 42 can modulate the polarization state of the polarized light and diffract the polarized light.

FIG. 5 is a photograph of experimental results showing the relationship between the polarized light incident on the

diffraction gratings

42, 46, 52, and 56 of the optical device 24 and the diffracted light. The diffraction grating shown in FIG. 5 corresponds to any one of the

diffraction gratings

42, 46, 52, and 56. The upper diagram of FIG. 5 is a diagram of the diffracted light projected on a plane substantially perpendicular to the traveling direction of the light. In the upper diagram of FIG. 5, the larger the white circle, the greater the intensity of the corresponding diffracted light. The lower diagram of FIG. 5 is a plan view showing the path of diffracted light diffracted by the diffraction grating. In the lower diagram of FIG. 5, the thicker the line, the greater the intensity of the diffracted light. As shown in FIG. 5, when the light incident on the diffraction grating of the optical device 24 is clockwise circularly polarized light, the diffraction grating maximizes the intensity of the −1st order light and increases the intensity of the + 1st order light. Is substantially zero. When the light incident on the diffraction grating of the optical device 24 is linearly polarized light, the diffraction grating makes the intensity of ± first-order light substantially equal and reduces the intensity of zero-order light. When the light incident on the diffraction grating of the optical device 24 is counterclockwise circularly polarized light, the diffraction grating maximizes the intensity of the + 1st order light and makes the intensity of the −1st order light substantially zero.

FIG. 6 is an exploded perspective view of the optical device 24. In FIG. 6, a direction parallel to both the front direction and the vertical direction is defined as a horizontal direction. In FIG. 6, the

substrates

40, 44, 50, 54, and 58 are omitted.

As shown in FIG. 6, the diffraction grating 42 has a grating pattern PG1 having stripes parallel to the horizontal direction. The direction in which the dotted line extends in the plane of the diffraction grating 42 in FIG. 6 is the direction in which the stripe extends. That is, the grating pattern PG1 of the diffraction grating 42 has periodicity along the vertical direction.

The diffraction grating 46 is preferably the same as the diffraction grating 42. An example in which the diffraction grating 42 and the diffraction grating 46 are the same is a form having the same function. In this case, the diffraction grating 42 and the diffraction grating 46 diffract polarized light of the same polarization state in the same direction when light of the same wavelength is incident. Therefore, when the diffraction grating 42 and the diffraction grating 46 are formed of different materials, the fact that the diffraction grating 42 and the diffraction grating 46 are the same includes a case where the structure such as the thickness is different if the functions are the same. It is. Another example in which the diffraction grating 42 and the diffraction grating 46 are the same is a form in which the grating patterns PG1 and PG2 have the same structure and the stripes of the grating patterns PG1 and PG2 are arranged in parallel to each other. . An example of a form in which the lattice patterns have the same structure here is a form in which the stripe periods of the lattice patterns PG1 and PG2 and the thicknesses of the lattice patterns PG1 and PG2 are the same. Note that the same stripe period means that the molecules 64 of the liquid crystal layer 62 constituting the lattice patterns PG1 and PG2 are made of the same material, and the alignment patterns of the molecules 64 are the same. Here, if the structures of the grating patterns PG1 and PG2 are the same and the stripes are arranged in parallel to each other, the positions of the diffraction grating 42 and the diffraction grating 46 are the direction in which the stripes extend or the direction of the periodicity of the stripes. It may be shifted to. That is, for example, when viewed from the incident side, the alignment directions of the molecules 64 of the liquid crystal layer 62 of the lattice patterns PG1 and PG2 overlapping in the same region may not be parallel to each other. Further, if the lattice patterns PG1 and PG2 have the same structure and the stripes are arranged in parallel to each other, one lattice pattern PG1 with respect to the other lattice pattern PG2, with the normal direction as the rotation axis, You may arrange | position in the state rotated 180 degrees. In this case, the alignment directions of the molecules 64 of the liquid crystal layer 62 are the same. When the alignment directions of the molecules 64 of the liquid crystal layer 62 are mirror images, that is, when the molecules 64 of the liquid crystal layer 62 are projected on the same surface, Includes symmetric relationships.

The diffraction grating 52 has a grating pattern PG3 having stripes parallel to the vertical direction. The diffraction grating 52 has the same grating pattern PG3 as the grating patterns PG1 and PG2 of the

diffraction gratings

42 and 46, and has a grating pattern PG3 of a stripe orthogonal to the stripes of the grating patterns PG1 and PG2 of the

diffraction gratings

42 and 46. .

The diffraction grating 56 has the same grating pattern PG4 as the grating pattern PG3 of the diffraction grating 52, and has a grating pattern PG4 arranged in parallel with the grating pattern PG3.

Next, the operation of the optical device 24 will be described.

First, light L00, which is linearly polarized laser light, enters the diffraction grating 42. Since the grating pattern PG1 of the diffraction grating 42 has periodicity in the vertical direction, the diffraction grating 42 diffracts the light L00 in the vertical direction. Thereby, the diffraction grating 42 emits the 0th-order light L10 traveling forward, the + 1st-order light L11 traveling obliquely upward, and the −1st-order light L12 traveling obliquely downward. The zero-order light L10 is linearly polarized light with the vertical direction as the polarization direction. Since the diffraction grating 42 is a liquid crystal polarization diffraction grating, the ± first-order lights L11 and L12 are emitted as circularly polarized light. The ± first-order lights L11 and L12 are circularly polarized lights that are reverse to each other. The ± nth-order light (n ≧ 2) has a weak intensity and is less affected by speckle noise, and therefore will not be described.

The lights L10, L11, and L12 emitted from the diffraction grating 42 enter the diffraction grating 46. Since the grating pattern PG2 of the diffraction grating 46 has periodicity in the vertical direction, the diffraction grating 46 diffracts incident light L10, L11, L12 in the vertical direction. Here, the diffraction grating 42 and the diffraction grating 46 have the same grating patterns PG1 and PG2 and are arranged in parallel to each other. Therefore, the diffraction grating 46 diffracts a part of the + 1st order light L11 incident while traveling obliquely upward, and becomes the −1st order light L22 traveling forward in the same direction as the traveling direction of the light L00 incident on the diffraction grating 42. Exit. The −1st order light L22 is circularly polarized light in the reverse direction of the + 1st order light L11. Further, the diffraction grating 46 diffracts a part of the −1st order light L12 incident while traveling obliquely downward, and as the + 1st order light L23 traveling forward in the same direction as the travel direction of the light L00 incident on the diffraction grating 42. Exit. Incidentally, the + 1st order light L23 is circularly polarized light in the reverse direction of the −1st order light L12. Thereby, the diffraction grating 46 emits the −1st order light L22 and the + 1st order light L23 as light having traveling directions parallel to each other. The diffraction grating 46 emits light L20 and L21 obtained by diffracting the 0th-order light L10 emitted from the diffraction grating 42 in the vertical direction. However, the intensity of the light L20 and L21 is weak, and thus the description thereof is omitted.

The lights L22 and L23 emitted from the diffraction grating 46 enter the quarter-wave plate 48. Since the lights L22 and L23 are circularly polarized light opposite to each other, the quarter-wave plate 48 emits the lights L22 and L23 as linearly polarized lights L30 and L31 whose polarization directions are orthogonal to each other. For example, the quarter wavelength plate 48 emits the −1st order light L22 as linearly polarized light L30 having a polarization direction parallel to the vertical direction. The quarter-wave plate 48 emits the + 1st order light L23 as linearly polarized light L31 having a polarization direction parallel to the horizontal direction.

The linearly polarized light L30 and L31 emitted from the quarter-wave plate 48 is incident on the diffraction grating 52. The diffraction grating 52 diffracts incident light. Here, since the grating pattern PG3 of the diffraction grating 52 has periodicity in the horizontal direction, the diffraction grating 52 diffracts and emits the incident linearly polarized light L30 and L31 in the horizontal direction. Therefore, the diffraction grating 52 emits the zero-order light L40 and the ± first-order lights L41 and L42 obtained by diffracting the linearly polarized light L30 having the vertical direction into the polarization direction in the horizontal direction. More specifically, the diffraction grating 52 includes zero-order light L40 that travels forward while maintaining the polarization state, circularly-polarized + first-order light L41 that travels in the diagonally left direction, and circularly polarized light that travels forward and diagonally to the right. Of the first-order light L42. The direction of the circularly polarized light of the + 1st order light L41 is opposite to the direction of the circularly polarized light of the −1st order light L42. On the other hand, the diffraction grating 52 emits 0th-order light L43 and ± first-order light L44 and L45 obtained by diffracting linearly polarized light L31 whose polarization direction is the horizontal direction in the horizontal direction. More specifically, the diffraction grating 52 includes a zero-order light L43 that travels forward while maintaining a polarization state, a circularly-polarized + 1st-order light L44 that travels in the diagonally left direction, and a circularly polarized light that travels in the diagonally forward right direction. Of the first-order light L45. The direction of the circularly polarized light of the + 1st order light L44 is opposite to the direction of the circularly polarized light of the −1st order light L45.

The lights L40, L41, L42, L43, L44, and L45 emitted from the diffraction grating 52 enter the diffraction grating 56. Since the grating pattern PG4 of the diffraction grating 56 has periodicity in the horizontal direction, the diffraction grating 56 diffracts incident light L40, L41, L42, L43, L44, and L45 in the horizontal direction. The diffraction grating 52 and the diffraction grating 56 have the same grating patterns PG3 and PG4 and are arranged in parallel to each other. Therefore, the diffraction grating 56 diffracts a part of the + 1st order light L41 and L44 incident while traveling in the left oblique direction, and proceeds forward in the same direction as the traveling direction of the linearly polarized light L30 and L31 incident on the diffraction grating 52. -Emitted as primary light L52, L56. The −1st order lights L52 and L56 are circularly polarized light in the reverse directions of the + 1st order lights L41 and L44, respectively. The diffraction grating 56 diffracts part of the −1st order light L42 and L45 incident while traveling in the right oblique direction, and travels forward in the same direction as the linearly polarized light L30 and L31 incident on the diffraction grating 52. Emitted as first-order light L53 and L57. The + 1st order lights L53 and L57 are circularly polarized light in the reverse directions of the −1st order lights L42 and L45, respectively. The diffraction grating 56 diffracts 0th-order light L40 and L43, which are linearly polarized light whose vertical or horizontal direction is the polarization direction, and travels as ± first-order light L50, L51, L54, and L55 that travel diagonally forward. Exit. Since the ± primary lights L50, L51, L54, and L55 have low intensity, the description thereof is omitted. As a result, the optical device 24 divides the incident light L00 in the horizontal direction and the vertical direction so that the intensity is weaker than that of the light L00, and four ± 1 traveling in parallel while overlapping each other. The secondary lights L52, L53, L56, and L57 are emitted.

FIG. 7 is a graph showing the relationship between the wavelength of light incident on the diffraction grating and the intensity of the 0th-order light emitted by the diffraction grating. In the experiment of FIG. 7, a diffraction grating having a grating pattern having a periodicity of 3 μm between stripes was used. As shown in FIG. 7, it can be seen that when the light having a wavelength of 532 nm is incident on a diffraction grating having an interval between stripes of 3 μm, the zero-order light can be weakened most. Therefore, a diffraction grating having a spacing of 3 μm between stripes can weaken the 0th order light of green light, which is highly sensitive to human eyes, and can reduce light spots.

FIG. 8 is a diagram for explaining variation in light emitted from the optical device 24. In FIG. 8, a region surrounded by a thin dotted line is one pixel PX. The light reflected by the stopped MEMS mirror 22 reaches one pixel PX. Here, the optical device 24 divides the light reflected by the MEMS mirror 22 into four light beams traveling in parallel and emits the light. In FIG. 8, four squares indicated by bold lines indicate the arrival areas of four light beams having high intensity among the divided lights. Of the four lights, two lights arranged on the diagonal line of the pixel PX are circularly polarized light around the same direction. The four lights are emitted by the diffraction grating 56 so as to overlap each other. It is preferable that the four lights fall within an area obtained by enlarging the pixel PX by 110%.

A specific example will be described in which the four divided lights fall within a region where the pixel PX is enlarged by 110%. The

substrates

40, 44, 50, 54, and 58 are glass substrates having a thickness of 0.21 mm. In this case, the total thickness of the optical device 24 is about 1.1 mm. The periodicity of the stripes of the grating patterns PG1 to PG4 of the

diffraction gratings

42, 46, 52, and 56 is 5.4 μm. In this case, the

diffraction gratings

42, 46, 52, and 56 emit ± first-order light obtained by diffracting light having a wavelength of 532 nm at a diffraction angle of 5.6666 degrees. When configured in this manner, the optical device 24 can store the four divided lights in an area where the pixel PX is enlarged by 110% under the condition that the size of the screen 30 is 12 inches and the resolution is 1280 × 720. .

As described above, the optical device 24 divides the light L00, which is an incident linearly polarized laser beam, into point-symmetric positions with the incident region as the center, has polarization directions that are symmetrical to each other, and is divided. Among the emitted light, the ± 1 st order light L52, L53, L56, L57 having high intensity is emitted so as to travel in parallel with each other. In this way, the optical device 24 can weaken the intensity by dividing the light and making the polarization directions symmetrical to each other. Further, the optical device 24 causes the ± primary lights L52, L53, L56, and L57 to travel in parallel by causing the ± primary lights L52, L53, L56, and L57 divided in a point-symmetric manner with the incident region as the center to travel in parallel. It is possible to suppress the formation of one pixel that is far away from each other. As a result, the optical device 24 can reduce speckle noise while suppressing image deterioration. Furthermore, since the optical device 24 does not need to drive the

diffraction gratings

42, 46, 52, and 56, the configuration can be simplified.

FIG. 9 is an exploded perspective view of an optical device 124 according to another embodiment. As shown in FIG. 9, the optical device 124 includes a diffraction grating 142 and a diffraction grating 146. The diffraction grating 142 and the diffraction grating 146 have the same configuration as the diffraction grating 42 and the diffraction grating 46 described above, and are arranged in the same direction. As in the above-described embodiment, a substrate is provided on each surface of the diffraction grating 142 and the diffraction grating 146.

Also in the optical device 124, light L00 which is linearly polarized laser light is incident on the

diffraction gratings

142 and 146. In this case, the

diffraction gratings

142 and 146 diffract a part of the light L00 and emit it as −1st order light L22 and + 1st order light L23, which are circularly polarized light traveling forward. Note that the rotation directions of the circularly polarized light of the −1st order light L22 and the + 1st order light L23 emitted from the diffraction grating 146 are opposite to each other. Thereby, the optical device 124 can reduce speckle noise by dividing the light L00 in the periodic direction of the grating pattern of the diffraction grating 142. Further, in the optical device 124, since the diffraction grating 146 emits the divided ± first-order lights L22 and L23 in parallel, it is possible to suppress the separation of the ± first-order lights L22 and L23, thereby suppressing image deterioration. .

FIGS. 10, 11 and 12 are cross-sectional views for explaining a form in which the arrangement of the

diffraction gratings

42 and 46 with respect to the

substrates

40 and 44 is changed. 10 to 12 are diagrams of the

substrates

40 and 44 and the

diffraction gratings

42 and 46, but the

substrates

50 and 54 and the

diffraction gratings

52 and 56 may be similarly changed. As shown in FIG. 10, the

diffraction gratings

42 and 46 may be disposed on the incident side of the

substrates

40 and 44, respectively. As shown in FIG. 11, the diffraction grating 42 may be disposed on the emission side of the substrate 40, and the diffraction grating 46 may be disposed on the incident side of the substrate 44. As shown in FIG. 12, the diffraction grating 42 may be arranged on the incident side of the substrate 40 and the diffraction grating 46 may be arranged on the emission side of the substrate 44.

13 and 14 are diagrams for explaining the orientation direction of the molecules 64 of the liquid crystal layer 62 of the

diffraction gratings

42 and 46 as viewed from the incident side. 13 and 14 are diagrams of the

diffraction gratings

42 and 46, but the same applies to the

diffraction gratings

52 and 56. FIG. 13 and 14 show the

diffraction gratings

42 and 46 shifted for the sake of explanation. Actually, in FIGS. 13 and 14, the four corners of the diffraction grating 42 and the four corners of the diffraction grating 46 are arranged to coincide with each other.

As shown in FIG. 13, the molecules 64 of the liquid crystal layer 62 of the diffraction grating 42 may be parallel to the molecules 64 of the liquid crystal layer 62 of the diffraction grating 46. For example, as shown in FIG. 2 and FIG. 10, it is effective for a configuration in which both of the

diffraction gratings

42 and 46 are arranged on the same side of the

substrates

40 and 44, that is, the incident side or the outgoing side. Thereby, an optical apparatus can be manufactured by bonding together diffraction gratings and substrates having the same structure.

On the other hand, as shown in FIG. 14, the molecules 64 of the liquid crystal layer 62 of the diffraction grating 42 are line-symmetric with respect to the molecules 64 of the liquid crystal layer 62 of the diffraction grating 46 and the direction of the periodicity of the stripes, ie, mirror images. It may be related. For example, as shown in FIGS. 11 and 12, the

diffraction gratings

42 and 46 are arranged on different sides of the

substrates

40 and 44, that is, on the incident side and the emission side, or on the emission side and the incident side, respectively. It is valid. Thereby, an optical apparatus can be manufactured by bonding together diffraction gratings and substrates having the same structure.

The orientation direction of the molecules 64 of the liquid crystal layer 62 of the

diffraction gratings

42 and 46 may be changed as appropriate. For example, in FIG. 13 and FIG. 14, the orientation direction of the molecules of the

diffraction gratings

42 and 46 may be a line-symmetrical direction with the direction of the periodicity of the stripe as the symmetry axis.

FIG. 15 is an exploded perspective view of an optical device 224 according to another embodiment. Linearly polarized light L00 with the vertical direction as the polarization direction is incident on the optical device 224. As shown in FIG. 15, the optical device 224 is an example of a quarter-wave plate 240, a birefringent member 242 that is an example of an incident-side modulator, a quarter-wave plate 244, and an exit-side modulator. A birefringent member 246. The

birefringent members

242, 246 are made of, for example, a material such as quartz.

The quarter-wave plate 240 is disposed on the most incident side in the optical device 224. The quarter-wave plate 240 modulates the incident light L00, which is linearly polarized laser light, into circularly polarized light L60 and emits it.

The birefringent member 242 is disposed on the exit side of the quarter wavelength plate 240. The birefringent member 242 has an optical axis inclined from the front, for example, an optical axis inclined by 45 ° in a side view. The optical axis here is a slow axis or a fast axis. The optical axis is parallel to the side surface normal to the horizontal direction. The birefringent member 242 divides the incident circularly polarized light L60 in the vertical direction and emits ordinary light L70 and extraordinary light L71. The ordinary light L70 is linearly polarized light whose polarization direction is a horizontal direction orthogonal to the optical axis. On the other hand, the extraordinary light L71 is linearly polarized light whose polarization direction is parallel to the optical axis, that is, the vertical direction parallel to the side surface.

The quarter wavelength plate 244 is disposed on the exit side of the birefringent member 242. The quarter-wave plate 244 modulates the ordinary light L70 and the extraordinary light L71, which are incident linearly polarized laser light, into a circularly polarized light L80 and a circularly polarized light L81 and emits the modulated light. The circularly polarized light L80 and the circularly polarized light L81 are circularly polarized lights that are reverse to each other.

The birefringent member 246 has an optical axis tilted from the front, for example, an optical axis tilted by 45 ° in plan view. The optical axis is parallel to the upper and lower surfaces whose normal is the vertical direction. The birefringent member 246 divides the circularly polarized light L80 and the circularly polarized light L81 in the left-right direction, and emits ordinary light L90, extraordinary light L91, ordinary light L92, and extraordinary light L93 that travel parallel to each other. That is, the birefringent member 246 divides light in a horizontal direction that is different from the direction in which the birefringent member 242 divides. Ordinary lights L90 and L92 are linearly polarized light whose polarization direction is the horizontal direction orthogonal to the optical axis. On the other hand, the extraordinary lights L91 and L93 are linearly polarized light whose polarization direction is parallel to the optical axis, that is, the vertical direction parallel to the top and bottom surfaces.

As described above, the optical device 224 divides the ordinary light L90, the extraordinary light L91, the ordinary light L92, and the extraordinary light L93 so that they are not arranged in a straight line. Accordingly, the optical device 224 can reduce variations in the positions of the ordinary light L90, the extraordinary light L91, the ordinary light L92, and the extraordinary light L93, and thus can suppress image degradation while reducing speckle noise.

In the embodiment, the

birefringent members

242 and 246 are exemplified as the incident-side modulation unit and the emission-side modulation unit. However, the incident-side modulation unit and the emission-side modulation unit have many polarization directions of linearly polarized light that is incident. Any configuration that modulates in the direction may be used. Therefore, the incident-side modulation unit and the emission-side modulation unit may be configured to emit circularly polarized light and natural light obtained by modulating the polarization direction of incident linearly polarized light in multiple directions.

Numerals and functions such as the arrangement, shape, number, etc. of each component in each embodiment described above may be changed as appropriate. Moreover, you may combine each embodiment and a part of each embodiment.

For example, the stripes of the grating patterns PG1 and PG2 of the

diffraction gratings

42 and 46 do not have to be orthogonal to the stripes of the grating pattern PG3, and need only intersect.

The relationship between the direction of the grating pattern of the diffraction grating and the polarization direction of linearly polarized light may be changed as appropriate. For example, the polarization direction of the linearly polarized light L00 may be inclined or parallel to the periodic direction of the grating pattern PG1. In this case, the ± first-order light is diffracted and emitted along the periodic direction of the grating pattern PG1. The same applies to the grating patterns of other diffraction gratings.

FIG. 16 is an overall configuration diagram of the optical device 324 with a part thereof changed. The optical device 324 includes an optical member 325 and a polarization switch 370. The optical member 325 has the same configuration as the optical device 24.

The polarization switch 370 is disposed on the optical path of light emitted as laser light. For example, the polarization switch 370 is provided on the emission side of the optical member 325. The polarization switch 370 switches the polarization state of the light emitted from the optical member 325 in a time division manner.

The polarization switch 370 includes a pair of

transparent electrodes

372 and 376 and a liquid crystal member 374 disposed between the pair of

transparent electrodes

372 and 376. The pair of

transparent electrodes

372 and 376 cover substantially the entire surface on the incident side and the surface on the emission side of the liquid crystal member 374. The voltage applied to the pair of

transparent electrodes

372 and 376 is controlled by the control unit 28. The liquid crystal member 374 functions as, for example, a half-wave plate depending on the applied voltage.

For example, the control unit 28 switches the voltage applied to the

transparent electrodes

372 and 376 every switching period T. An example of the switching period T is 20 msec. The voltage may be an alternating current with a switching period T, or a direct current with which the voltage switches discontinuously in the switching period T. Thereby, the alignment direction of the liquid crystal molecules of the liquid crystal member 374 changes every switching period T. Here, when clockwise circular polarized light is incident, the polarization switch 370 emits counterclockwise circular polarized light at a certain time, and emits clockwise circular polarized light as it is after a switching period T from that time. Thereby, since speckle noise is formed in a different position for every switching period T, the influence of the speckle noise on the viewer can be reduced.

FIG. 17 is an overall configuration diagram of the optical device 424 with a part thereof changed. The optical device 424 includes an optical member 325 and a polarization conversion unit 480. The polarization conversion unit 480 is arranged on the optical path of L00, which is laser light, and converts incident light into light having different polarization states and traveling in the same direction. An example of the same direction is a direction substantially parallel to each other, preferably a direction parallel to each other. For example, the polarization conversion unit 480 is disposed on the output side of the optical member 325. The polarization conversion unit 480 includes a polarization beam splitter 482, a quarter wavelength plate 484, a reflection member 486, a quarter wavelength plate 488, and a reflection member 490.

The central surface 483 of the polarization beam splitter 482 transmits a component in one vibration direction and reflects a component in another vibration direction in the light incident from the optical member 325. For example, one vibration direction and the other vibration direction are orthogonal to each other. For example, when circularly polarized light is incident, the central surface 483 transmits a vibration component in a horizontal direction (for example, a direction parallel to the paper surface) among vibration components included in the circularly polarized light, and the vertical surface (for example, the paper surface). The vibration component in the direction perpendicular to the surface is reflected. Therefore, the central surface 483 emits the transmitted light to the quarter-wave plate 484 as linearly polarized light having the horizontal direction as the polarization direction, and reflects the reflected light as 1 linearly polarized light having the vertical direction as the polarization direction. The light is emitted to the / 4 wavelength plate 488. The quarter-

wave plates

484 and 488 convert the polarization direction of the transmitted light. Here, since the light transmitted through the quarter-

wave plates

484 and 488 is reflected by the reflecting

members

486 and 490, the light passes through the quarter-

wave plates

484 and 488 twice. Accordingly, the

quarter wave plates

484 and 488 function as half wave plates. Thereby, the

quarter wavelength plates

484 and 488 convert the polarization direction of the linearly polarized light when the light transmitted twice is linearly polarized light. For example, the quarter-wave plate 484 rotates linearly polarized light whose horizontal direction is the polarization direction by 90 °, converts it into linearly polarized light whose vertical direction is the polarization direction, and emits it to the central plane 483. On the other hand, the ¼ wavelength plate 488 rotates the linearly polarized light whose vertical direction is the polarization direction by 90 °, converts it into the linearly polarized light whose horizontal direction is the polarization direction, and emits it to the central plane 483.

Therefore, the light transmitted through the central surface 483 of the polarizing beam splitter 482 is returned to the linearly polarized light whose polarization direction is rotated by 90 ° by the quarter wavelength plate 484 and whose vertical direction is the polarization direction. Reflected by the surface 483. On the other hand, the light reflected by the central surface 483 of the polarizing beam splitter 482 is rotated by 90 ° by the quarter wavelength plate 488 and returned as linearly polarized light having the horizontal direction as the polarization direction. Therefore, the light passes through the surface 483. As a result, the polarization conversion unit 480 converts the incident light into light having different polarization states and traveling in parallel with each other, and outputs the light. It should be noted that the polarization conversion unit 480 converts the light incident on the polarization beam splitter 482 into linearly polarized light having different polarization directions and traveling parallel to each other, and outputs the linearly polarized light.

As described above, the optical device 424 converts the polarized light beams having different polarization directions into parallel polarized light beams that travel in parallel with each other and emits the polarized light beams. Thereby, the optical device 424 further disperses the speckle noise, so that the influence of the speckle noise can be reduced.

FIG. 18 is an overall configuration diagram of the optical device 524 with a part thereof changed. The optical device 524 includes an optical member 325, a polarization conversion unit 480, and a polarization switch 370. In the optical device 524, the optical member 325, the polarization conversion unit 480, and the polarization switch 370 are arranged in this order along the light traveling direction.

Next, an experiment conducted to prove the effect of speckle noise reduction of each embodiment described above will be described.

FIG. 19 is a schematic diagram of an experimental apparatus for examining speckle noise reduction. In this experiment, a green laser device 692 that emits green laser light was used as a light source. Laser light was emitted to the optical device 624 by the green laser device 692. The laser light has a beam diameter of 2 mm at a wavelength of 532 nm. The light that passed through the optical device 624 and was projected onto the pseudo-diffusing sphere 694 was photographed with a digital single-lens reflex camera (D40 manufactured by Nikon Corporation). The gradation distribution in the plane of the photographed image was calculated by image processing software. The gradation distribution was calculated as a 10 mm × 10 mm square around the center of the pseudo-diffusing sphere 694 as an evaluation area. The gradation distribution was calculated from each of the images captured three times by each optical device 624. From the calculated gradation distribution, the average gradation of the gradation distribution in the evaluation area, the standard deviation of the gradation distribution in the evaluation area, and the speckle contrast were calculated. The speckle contrast was calculated by the following equation.
Speckle contrast = (Standard deviation of evaluation area) / (Average gradation of evaluation area)
Further, an average speckle contrast, which is an average of three speckle contrasts, was calculated.

Note that as the optical device 624, an optical device 24, an optical device 324, an optical device 424, and an optical device 524 were used. In addition, the pitch of the diffraction grating of the optical device 24 and the optical member 325 was set to 5.2 μm. For comparison, the same experiment was performed for a configuration without an optical device (described as “no element” in the table).

FIG. 20 shows the results of an experiment that proves the reduction of speckle noise. As shown in FIG. 20, it can be seen that the optical device 24 can reduce the average speckle contrast by about 26% compared to the case where there is no element such as an optical device. In other words, the optical device 24 can reduce speckle noise while not requiring voltage control unlike the polarization switch 370 and suppressing the enlargement of the polarization conversion unit 480.

Furthermore, it can be seen that the

optical devices

324, 424, and 524 combined with the optical device 24 and at least one of the polarization switch 370 or the polarization conversion unit 480 can reduce the average speckle contrast by at least 34% compared to the case without the element. In particular, it can be seen that the optical device 524 that combines the optical device 24, the polarization switch 370, and the polarization conversion unit 480 can reduce the average speckle contrast by 58%.

The arrangement of the

optical devices

324, 424, and 524 described above may be changed as appropriate. For example, they may be arranged in the following arrangement order.
Polarization switch 370 → optical member 325 → polarization converter 480
Optical member 325 → polarization switch 370 → polarization converter 480
Polarization conversion unit 480 → polarization switch 370 → optical member 325
Polarization conversion unit 480 → optical member 325 → polarization switch 370
Polarization switch 370 → optical member 325

FIG. 21 is a perspective view of a diffraction grating 724 in which a part of the diffraction grating 42 is changed. The diffraction grating 724 includes a plate-like transparent electrode 766, a liquid crystal layer 767, and a plurality of linear transparent electrodes 768.

The plate-like transparent electrode 766 is provided on one surface of the liquid crystal layer 767, for example, the incident side surface. The plate-like transparent electrode 766 covers substantially the entire surface of the liquid crystal layer 767. The horizontal length of the linear transparent electrode 768 has the same length as one side of the plate-shaped transparent electrode 766 in the horizontal direction. The length of the linear transparent electrode 768 in the vertical direction is shorter than the length of one side of the plate-shaped transparent electrode 766 in the vertical direction. In other words, the linear transparent electrode 768 has a shape obtained by dividing the plate-like transparent electrode 766 in the vertical direction. The linear transparent electrodes 768 are arranged in parallel with each other at equal intervals along the vertical direction. Thereby, the linear transparent electrodes 768 are electrically insulated from each other.

The plate-like transparent electrode 766 and the linear transparent electrode 768 are connected to the control unit 28 which is an example of an electrode control unit. The control unit 28 controls the voltage applied to the plate-like transparent electrode 766 and the linear transparent electrode 768. The liquid crystal layer 767 has a different refractive index depending on an applied voltage. Accordingly, the liquid crystal layer 767 has a refractive index difference between the regions, and functions as a diffraction grating.

Furthermore, the control unit 28 can have the same function as when the period of the grating in the diffraction grating is changed by changing the period of the linear transparent electrode 768 to which the same voltage is applied. For example, the control unit 28 sets the period of the grating of the diffraction grating 724 when the same voltage is applied at intervals of one line from the top, such as the first line, the third line, and the fifth line. The grating period of the diffraction grating 724 when applied at intervals of two lines such as the fifth line and the sixth line can be halved. Thereby, the diffraction grating 724 can realize different configurations of the diffraction function under the control of the control unit 28. As a result, the diffraction grating 724 can control the dispersion of light that causes speckle noise even when light of different wavelengths is incident. Therefore, speckle noise can be reduced while reducing the influence of light wavelength. Can be reduced. Note that the same configuration as that of the diffraction grating 724 may be applied to diffraction gratings other than the diffraction grating 42.

As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

The execution order of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior”. It should be noted that they can be implemented in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for the sake of convenience, it means that it is essential to carry out in this order. is not.

10 projectors, 12 laser light sources, 14 laser light sources, 16 laser light sources, 18 dichroic mirrors, 20 dichroic mirrors, 22 MEMS mirrors, 24 optical devices, 26 projection units, 40 control units, screens, 42 control units. Substrate, 46 diffraction grating, 48 1/4 wavelength plate, 50 substrate, 52 diffraction grating, 54 substrate, 56 diffraction grating, 58 substrate, 60 orientation layer, 62 liquid crystal layer, 64 molecule, device, 124 Diffraction grating, 224 optical device, 240 1/4 wavelength plate, 242 birefringent member, 244 1/4 wavelength plate, 244 quarter wavelength plate, 246 birefringent member, 324 optical device, 325 optical member, 370 polarization switch, 372 transparent electrode, liquid crystal 37 4 Electrode, 424 optical device, 480 polarization converter, 482 polarizing beam splitter, 483 surface, 484 quarter wavelength plate, 486 reflective member, 488 quarter wavelength plate, 490 reflective member, optical device 524, 69 Green laser device, 694 pseudo-diffusing sphere, 724 diffraction grating, 766 plate-shaped transparent electrode, 767 the liquid crystal layer, 768 linear transparent electrodes

Claims

A diffraction unit that diffracts and emits linearly polarized laser light;
An optical device comprising: a direction changing unit that converts at least a part of the + 1st order light emitted from the diffraction unit and at least a part of the −1st order light into parallel directions and emits the converted light.
A quarter-wave plate that is provided on the exit side of the direction conversion unit and converts the light emitted by the direction conversion unit into linearly polarized light;
A second diffractive part that diffracts and emits the linearly polarized light emitted from the quarter-wave plate in a direction different from the diffraction direction of the diffractive part;
2. The second direction conversion unit further comprising: a second direction conversion unit that converts at least a part of the + 1st order light diffracted by the second diffraction unit and at least a part of the −1st order light into parallel directions and outputs the parallel direction. Optical device.
The diffraction part includes a first diffraction grating,
The optical device according to claim 1, wherein the direction changing unit includes a second diffraction grating having the same function as the first diffraction grating.
The diffraction part includes a first diffraction grating,
4. The device according to claim 1, wherein the direction changing unit includes a second diffraction grating having the same structure as the first grating pattern of the first diffraction grating and having a second grating pattern arranged in parallel. 5. The optical device according to item 1.
A quarter-wave plate that is provided on the exit side of the direction conversion unit and converts the light emitted by the direction conversion unit into linearly polarized light;
A second diffractive portion including a third diffraction grating that diffracts and emits the linearly polarized light emitted from the quarter-wave plate in a direction different from the diffraction direction of the diffractive portion;
A fourth diffraction grating having the same function as the third diffraction grating, wherein at least a part of the + 1st order light and at least a part of the −1st order light diffracted by the second diffraction part are converted into parallel directions. The optical device according to claim 3, further comprising a second direction conversion unit that emits light.
A quarter-wave plate that is provided on the exit side of the direction conversion unit and converts the light emitted by the direction conversion unit into linearly polarized light;
A second diffractive part that diffracts and emits the linearly polarized light emitted from the quarter-wave plate in a direction different from the diffraction direction of the diffractive part;
A second direction converter that converts at least a part of the + 1st order light diffracted by the second diffractive part and at least a part of the −1st order light into parallel directions and emits the converted light;
The second diffraction part includes a third diffraction grating having a third grating pattern intersecting with the first grating pattern,
5. The optical device according to claim 4, wherein the second direction changing unit includes a fourth diffraction grating having the same structure as the third grating pattern and having a fourth grating pattern arranged in parallel.
The optical device according to claim 6, wherein the first grating pattern is orthogonal to the third grating pattern.
The optical device according to claim 3, wherein the first diffraction grating and the second diffraction grating have a liquid crystal unit that diffracts polarized light.
The optical device according to claim 2, wherein the direction changing unit or the second direction changing unit diffracts the emitted light so as to overlap each other.
An incident-side modulator that modulates the polarization direction of linearly polarized laser light in multiple directions;
A first birefringence unit that divides light modulated by the incident side modulation unit in a first direction and emits first light and second light;
An emission-side modulation unit that modulates the polarization directions of the first light and the second light emitted from the first birefringence unit in multiple directions;
An optical device comprising: a second birefringence unit that divides the light modulated by the emission side modulation unit in a second direction different from the first direction and emits the light traveling in parallel with each other.
The optical device according to any one of claims 1 to 10, further comprising a polarization switch that is disposed on an optical path of the laser light and switches a polarization state of incident light in a time division manner.
12. The apparatus according to claim 1, further comprising a polarization conversion unit that is disposed on an optical path of the laser light and converts incident light into light having different polarization states and traveling in the same direction. An optical device according to 1.
The liquid crystal part
A planar liquid crystal member;
A plurality of first transparent electrodes extending in one direction and provided in parallel to one surface of the liquid crystal member;
The optical device according to claim 8, further comprising a second transparent electrode provided on an opposite side of the plurality of first transparent electrodes with the liquid crystal member interposed therebetween.
An electrode controller that controls a voltage applied to the plurality of first transparent electrodes and the second transparent electrodes;
The optical device according to claim 13, wherein the electrode control unit individually controls the plurality of first transparent electrodes.