Optical devices and optical apparatus

Abstract

To provide an optical device in which an arrangement pattern of parallel light in a plane vertical to an optical axis can be quickly and freely switched.SOLUTION: In an optical device 1A, a first lens array 30 condenses first parallel light L1 by a plurality of first lenses 31. A second lens array converts light L2 output from the plurality of first lenses 31 to second parallel light L3. An electro-optic crystalline substance body 10 receives the second parallel light L3 upon a principal plane 11. A light reflection portion 13 is arranged on a rear surface 12 side of the electro-optic crystalline body 10. A plurality of electric field formation portions 20 form in the electro-optic crystalline body 10, electric fields in which intensity periodically vary. The second array lens 50 converges the second parallel light L3 output from the electro-optic crystalline body 10 by a plurality of second lenses 51. An optical shielding member 40 causes light L4 converged by each of the plurality of second lenses 51 to transmit or shield in each of a plurality of areas 41 in accordance with an electric field state of the corresponding electric field formation portion 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0004] , , , , , , , , , , , , , ,

[0003] , , , , , , ,

[0001] The present disclosure relates to an optical device and an optical apparatus.

Background Art

[0002] Patent Documents 1 to 7 disclose optical modulators. Those optical modulators include an electro-optic crystal and a plurality of electrodes that individually form an electric field inside the electro-optic crystal. The electro-optic crystal is, for example, a perovskite-type electro-optic crystal having a relative permittivity of 1000 or more. The electro-optic crystal is, for example, a KTN crystal, a KLTN crystal, or a PLZT crystal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

[0005] The present disclosure aims to provide an optical device that can quickly and freely switch the arrangement pattern of parallel light in a plane perpendicular to the optical axis, and an optical apparatus that can speed up the switching of modulation patterns. [Means for solving the problem]

[0006] [1] The optical device according to this disclosure comprises a first lens array, a second lens array, a plate-shaped electro-optic crystal, a light-reflecting portion, a plurality of field-forming portions, and a light-shielding member. The first lens array has a plurality of first lenses arranged in a one-dimensional or two-dimensional manner, and each of the plurality of first lenses focuses first parallel light. The second lens array has a plurality of second lenses corresponding to the plurality of first lenses, and each of the plurality of second lenses converts the light output from each of the plurality of first lenses into second parallel light. The electro-optic crystal has a main surface and a back surface, and the main surface receives the second parallel light. The light-reflecting portion is located on the back surface of the electro-optic crystal and reflects the second parallel light toward the main surface. The plurality of field-forming portions are located corresponding to each of the plurality of second lenses. The plurality of field-forming portions form an electric field within the electro-optic crystal whose strength changes periodically in a direction along the front or back surface, and are configured so that the state of the electric field can be controlled independently of each other. The second lens array focuses the second parallel light, which has been reflected by the light reflecting section and output from the main surface of the electro-optic crystal, using each of the multiple second lenses. The light shielding member is positioned between the first lens array and the second lens array. The light shielding member has multiple electric field forming sections and multiple regions corresponding to each section, and is configured to allow light focused by each of the multiple first lenses to pass through each of the multiple regions, and to allow or shield light focused by each of the multiple second lenses to pass through each of the multiple regions, depending on the electric field state of the corresponding electric field forming section. The first lens array converts the light that has been focused by the second lenses and passed through the light shielding member into output light, which is parallel light, using the first lenses.

[0007] In the optical device described in [1] above, when an electric field is formed inside the electro-optic crystal by a certain electric field forming part, a periodic change in refractive index instantaneously occurs in the region inside the electro-optic crystal corresponding to that electric field forming part. When a second parallel light passes through an electro-optic crystal in which a periodic change in refractive index is occurring, the phase distribution of the second parallel light changes. Therefore, when the second parallel light is focused by the second lens, the light is focused at multiple separate focal points. In contrast, when no electric field is formed inside the electro-optic crystal by each of the multiple electric field forming parts, no periodic change in refractive index occurs inside the electro-optic crystal. Even when a second parallel light passes through such an electro-optic crystal, there is no change in the phase distribution of the second parallel light. Therefore, when the second parallel light is focused by the second lens, the light is focused at a single focal point.

[0008] Each region of the light shielding member allows or blocks light focused by the corresponding second lens, depending on the state of the electric field in the corresponding electric field forming section. In one example, each region of the light shielding member blocks light when it is focused at multiple separated focal points, and allows light to pass through when it is focused at a single focal point. In another example, each region of the light shielding member allows light to pass through when it is focused at multiple separated focal points, and blocks light when it is focused at a single focal point. Therefore, it is possible to freely determine whether each portion of the second parallel light, corresponding to multiple electric field forming sections, passes through the light shielding member. The light that passes through the light shielding member from the light focused by the second lens array is converted into parallel light output by the first lens and output to the outside of the optical device. Therefore, by switching the electric field forming sections that form the electric field, the arrangement pattern of parallel light in a plane perpendicular to the optical axis can be switched quickly and freely.

[0009] [2] In the optical device described in [1] above, each of the multiple electric field forming sections may have a first electrode provided on the main surface and a second electrode provided on the back surface. The first electrode is a transparent electrode, and one or both of the first and second electrodes may have a structure that is periodic in direction. In this case, a configuration in which a periodic electric field is formed within the electro-optic crystal while the main surface of the electro-optic crystal receives second parallel light can be easily realized.

[0010] [3] In the optical device described in [2] above, one or both of the first and second electrodes may be comb-shaped. In this case, the number of connection points between the first and / or second electrodes, which include a periodic structure, and the wiring for applying voltage to the electrodes can be reduced, thus simplifying the structure for applying voltage to the electrodes.

[0011] [4] In any one of the optical devices described in [1] to [3] above, each of the multiple regions of the light shielding member may be configured to allow light focused by each of the multiple second lenses to pass through when the electric field of the corresponding electric field forming unit is off, and to shield it when the electric field of the corresponding electric field forming unit is on. When the electric field of the electric field forming unit is on, a periodic refractive index distribution is generated within the electro-optic crystal, and the phase distribution of the second parallel light changes. When output light is generated from this second parallel light, the phase distribution remains in the output light, and the optical elements placed downstream of the optical device are affected by this phase distribution. In contrast, when the electric field of the electric field forming unit is off, the refractive index distribution within the electro-optic crystal does not change, and the phase distribution of the second parallel light does not change. Therefore, by allowing light focused by the second lens to pass through when the electric field of the electric field forming unit is off, the influence on the optical elements placed downstream of the optical device can be reduced.

[0012] [5] In any one of the optical devices described in [1] to [4] above, each of the plurality of first lenses and each of the plurality of second lenses may be a cylindrical lens that primarily has refractive power in the direction in which the strength of the electric field changes periodically. Each of the plurality of regions may include a slit that extends along the direction in which the cylindrical lens extends. In this case, it is sufficient to align the focusing position of the cylindrical lens with the slit only in the direction in which the cylindrical lens primarily has refractive power. Thus, the manufacturing of the optical device can be simplified.

[0013] [6] Another optical device according to the present disclosure comprises a plate-shaped electro-optic crystal, a plurality of field forming sections, a first lens array, a light reflecting section, and a light absorbing section. The electro-optic crystal has a main surface and a back surface, receiving first parallel light on the main surface and outputting first parallel light from the back surface. The plurality of field forming sections are arranged in a one-dimensional or two-dimensional manner in a plane along the front or back surface of the electro-optic crystal. The plurality of field forming sections form an electric field within the electro-optic crystal whose strength changes periodically in the direction along the front or back surface, and are configured to allow the state of the electric field to be controlled independently of each other. The first lens array has a plurality of first lenses corresponding to the plurality of field forming sections, and each of the plurality of first lenses focuses the first parallel light output from the back surface of the electro-optic crystal. The light reflecting section has a plurality of regions corresponding to the plurality of field forming sections, and is configured to reflect or pass through each of the plurality of regions the light focused by each of the plurality of first lenses according to the state of the electric field of the corresponding field forming section. The light absorbing section is configured to absorb the light that has passed through the light reflecting section. The first lens array converts the light reflected by the light reflecting section into parallel output light using the first lens. The electro-optic crystal transmits the output light.

[0014] In the optical device described in [6] above, when an electric field is formed inside the electro-optic crystal by a certain electric field forming part, a periodic change in refractive index instantaneously occurs in the region inside the electro-optic crystal corresponding to that electric field forming part. When a first parallel light passes through an electro-optic crystal in which a periodic change in refractive index is occurring, the phase distribution of the first parallel light changes. Therefore, when the first parallel light is focused by the first lens, the light is focused at multiple separate focal points. In contrast, when no electric field is formed inside the electro-optic crystal by each of the multiple electric field forming parts, no periodic change in refractive index occurs inside the electro-optic crystal. When a first parallel light passes through such an electro-optic crystal, there is no change in the phase distribution of the first parallel light. Therefore, when the first parallel light is focused by the first lens, the light is focused at a single focal point.

[0015] Each region of the light-reflecting section reflects or passes through the light focused by the corresponding first lens, depending on the state of the electric field in the corresponding electric field forming section. In one example, each region of the light-reflecting section passes through the light when it is focused at multiple separate focal points, and reflects the light when it is focused at a single focal point. In another example, each region of the light-reflecting section reflects the light when it is focused at multiple separate focal points, and passes the light when it is focused at a single focal point. Therefore, it is possible to freely determine, for each part, whether or not multiple parts corresponding to multiple electric field forming sections in the first parallel light are reflected by the light-reflecting section. The light reflected by the light-reflecting section from the light focused by the first lens array is converted into output light, which is parallel light, by the first lens and output to the outside of the optical device. The light that passes through the light-reflecting section from the light focused by the first lens array is absorbed and disappears by the light-absorbing section. Therefore, by switching the electric field generating unit that forms the electric field, the arrangement pattern of parallel light in a plane perpendicular to the optical axis can be switched quickly and freely.

[0016] [7] In the optical device described in [6] above, each of the plurality of field forming sections has a first electrode provided on the main surface and a second electrode provided on the back surface, and the first electrode and the second electrode may be transparent electrodes. One or both of the first electrode and the second electrode may include a structure that is periodic in the above direction. In that case, a configuration in which the first parallel light and the output light pass through the electro-optic crystal while a periodic electric field is formed in the electro-optic crystal can be easily realized.

[0017] [8] In the optical device described in [7] above, one or both of the first and second electrodes may be comb-shaped. In this case, the number of connection points between the first and / or second electrodes, which include a periodic structure, and the wiring for applying voltage to these electrodes can be reduced, thus simplifying the structure for applying voltage to the electrodes.

[0018] [9] In any one of the optical devices described in [6] to [8] above, each of the multiple regions of the light reflection section may be configured to reflect the light focused by each of the multiple first lenses when the electric field of the corresponding electric field forming section is off, and to allow the light to pass through when the electric field of the corresponding electric field forming section is on. When the electric field of the electric field forming section is on, a periodic refractive index distribution is generated within the electro-optic crystal, and the phase distribution of the first parallel light changes. When output light is generated from the first parallel light, this phase distribution remains in the output light as well. In addition, the phase distribution of the output light also changes when the output light passes through the electro-optic crystal. Therefore, optical elements placed downstream of the optical device are affected by these phase distributions. In contrast, when the electric field of the electric field forming section is off, the refractive index distribution within the electro-optic crystal does not change, and the phase distributions of the first parallel light and the output light do not change. Therefore, by reflecting the light focused by the first lens when the electric field of the electric field forming section is off, the influence on optical elements placed downstream of the optical device can be reduced.

[0019]

[10] In any one of the optical devices [6] to [9] above, each of the plurality of first lenses is a cylindrical lens that mainly has a refractive power in a direction in which the strength of an electric field changes periodically, and each of the plurality of regions may include a light reflecting surface that extends along the extending direction of the cylindrical lens. In that case, it is sufficient to align the condensing position of the cylindrical lens and the light reflecting surface only in the direction in which the cylindrical lens mainly has a refractive power. Therefore, the manufacture of the optical device can be simplified.

[0020]

[11] Any one of the optical devices [1] to

[10] above may further include a wiring board on which an electro-optical crystal is mounted. The wiring board may be electrically connected to each of the plurality of electric field forming portions and may have a plurality of terminals that respectively supply driving voltages to the plurality of electric field forming portions. In that case, driving voltages can be easily supplied to the plurality of electric field forming portions through the wiring board.

[0021]

[12] In any one of the optical devices [1] to

[11] above, the electro-optical crystal may include a KTN crystal.

[0022]

[13] The optical apparatus according to the present disclosure may include any one of the optical devices [1] to

[12] above and a liquid crystal type spatial light modulator that receives the output light output from the optical device and modulates the phase of the output light for each pixel. The spatial light modulator may have a plurality of modulation regions respectively corresponding to the plurality of electric field forming portions of the optical device. According to this optical apparatus, the switching of the modulation pattern can be accelerated while sacrificing the resolution. ​​​​​​

[15] Another optical device according to the present disclosure comprises one of the optical devices described in [1] to

[12] above, a light source that outputs a first parallel light, a polarizer that linearly polarizes the first parallel light output from the light source, a polarizing beam splitter that transmits or reflects the linearly polarized first parallel light to guide the first parallel light to the optical device, and a quarter-wave plate positioned in the optical path between the polarizing beam splitter and the optical device. The polarizing beam splitter reflects or transmits the output light that has been output from the optical device and passed through the quarter-wave plate. With this optical device, the output light can be separated and extracted from the first parallel light while suppressing a decrease in the light intensity of the output light. [Effects of the Invention]

[0025] According to this disclosure, it is possible to provide an optical device that can quickly and freely switch the arrangement pattern of parallel light in a plane perpendicular to the optical axis, and an optical device that can speed up the switching of modulation patterns. [Brief explanation of the drawing]

[0026] [Figure 1] Figure 1 is a cross-sectional view showing the configuration of an optical device according to the first embodiment of this disclosure. [Figure 2] Figures 2(a) and (b) are enlarged perspective views showing the electro-optic crystal and multiple field-forming regions. [Figure 3] Figure 3(a) is a schematic diagram showing the state inside the electro-optic crystal when no electric field is formed. Figure 3(b) is a schematic diagram showing the state inside the electro-optic crystal when an electric field is formed. [Figure 4] Figures 4(a), (b), and (c) are schematic diagrams illustrating examples of switching output light. [Figure 5] Figure 5 is a perspective view showing an example of a method for supplying voltage to the first and second electrodes. [Figure 6] Figure 6 is a perspective view showing another example of a method for supplying voltage to the first and second electrodes. [Figure 7]Figure 7 is a cross-sectional view showing the configuration of an optical device according to the first modified example. [Figure 8] Figure 8 is a cross-sectional view showing the configuration of an optical device according to the second modified example. [Figure 9] Figure 9 is a cross-sectional view showing the configuration of the optical device according to the second embodiment. [Figure 10] Figure 10 is a schematic diagram showing the configuration of the optical device according to the third embodiment. [Figure 11] Figure 11 is a schematic diagram showing the configuration of the optical device according to the fourth embodiment. [Figure 12] Figure 12 shows the optical modulation surface of the SLM. [Figure 13] Figure 13 is a flowchart showing the operation of the optical device. [Figure 14] Figure 14 is a timing chart showing an example of the operation of an optical device. [Figure 15] Figure 15 is a schematic diagram showing the configuration of the optical device according to the fifth embodiment. [Figure 16] Figure 16(a) is a schematic diagram showing the state inside the electro-optic crystal when no electric field is formed. Figure 3(b) is a schematic diagram showing the state inside the electro-optic crystal when an electric field is formed. [Modes for carrying out the invention]

[0027] Embodiments of optical devices and optical apparatuses according to this disclosure will be described in detail below with reference to the attached drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted. (First Embodiment)

[0028] Figure 1 is a cross-sectional view showing the configuration of an optical device 1A according to the first embodiment of the present disclosure. As shown in Figure 1, the optical device 1A of this embodiment comprises a plate-shaped electro-optic crystal 10, a light-reflecting portion 13, a plurality of electric field forming portions 20, a first lens array 30, a light-shielding member 40, and a second lens array 50.

[0029] The electro-optic crystal 10 includes, for example, at least one crystal from among KTN crystal, potassium niobate, lithium niobate, potassium tantalate, lithium tantalate, potassium dihydrogen phosphate, dipotassium phosphate, and barium titanate. The KTN crystal is a mixed crystal of potassium niobate and potassium tantalate and exhibits the photo-Kerr effect as an electro-optic effect. In one example, the electro-optic crystal 10 consists of a KTN crystal. The electro-optic crystal 10 has a main surface 11 and a back surface 12. In one example, the main surface 11 and the back surface 12 are parallel to each other. The thickness direction of the electro-optic crystal 10 coincides with the normal direction of the main surface 11 and the back surface 12.

[0030] Multiple electric field forming units 20 are arranged in a one-dimensional or two-dimensional manner within the plane along the main surface 11 and / or back surface 12. Figure 1 shows an example where three electric field forming units 20 are arranged in a row, but the number of electric field forming units 20 and the number of rows are not limited to this. Multiple electric field forming units 20 form an electric field within the electro-optic crystal 10 whose strength changes periodically in the direction D1 along the main surface 11 and / or back surface 12 of the electro-optic crystal 10. The state of each of the multiple electric field forming units 20 is configured to be independently controllable.

[0031] Figures 2(a) and 2(b) are enlarged perspective views of the electro-optic crystal 10 and the multiple field-forming sections 20. Figure 2(a) is a perspective view of the electro-optic crystal 10 seen from the main surface 11 side, and Figure 2(b) is a perspective view of the electro-optic crystal 10 seen from the back surface 12 side. As shown in Figure 2(a), a first electrode 21 (first electrode) is provided on the entire surface of the main surface 11 of the electro-optic crystal 10. In the figure, the region where the first electrode 21 is located is indicated by halftone dots. As shown in Figure 2(b), a plurality of (three in the illustrated example) second electrodes 22 (second electrodes) are provided on the back surface 12 of the electro-optic crystal 10. In the figure, the region where the second electrodes 22 are located is indicated by halftone dots. The first electrode 21 is a transparent electrode. The second electrodes 22 may be transparent electrodes or opaque electrodes (for example, metal electrodes). The constituent material of the transparent electrode is, for example, tin-doped indium oxide such as tin oxide, or fluorine-doped tin oxide. The first electrode 21 and the second electrode 22 are formed on the surface of the electro-optic crystal 10, for example by vacuum deposition.

[0032] Each of the multiple second electrodes 22 includes a structure that is periodic in direction D1. A periodic structure is, for example, a structure in which regions where the second electrode 22 is present and regions where the second electrode 22 is absent are arranged periodically and alternately. In one example, the second electrode 22 is comb-shaped with multiple comb teeth arranged in direction D1.

[0033] Each of the multiple electric field forming sections 20 is composed of a second electrode 22 and a region of the first electrode 21 facing the second electrode 22. The electro-optic crystal 10 has a second-order electro-optic effect called the optical Kerr effect, and when a voltage is applied between a second electrode 22 and a first electrode 21, an electric field is formed in the portion of the electro-optic crystal 10 between them, corresponding to the magnitude of the voltage. Figure 3(a) is a schematic diagram showing the state inside the electro-optic crystal 10 when no electric field is formed. Figure 3(b) is a schematic diagram showing the state inside the electro-optic crystal 10 when an electric field is formed. As shown in Figure 3(a), when no electric field is formed between the first electrode 21 and the second electrode 22, the refractive index distribution inside the electro-optic crystal 10 is uniform in direction D1. In contrast, as shown in Figure 3(b), when an electric field is formed between the first electrode 21 and the second electrode 22, the refractive index of the region A1 where the electric field is formed inside the electro-optic crystal 10 changes instantaneously with respect to other regions. As a result, in the region inside the electro-optic crystal 10 corresponding to the electric field forming portion 20, the refractive index changes periodically and instantaneously along direction D1, and the refractive index distribution forms a binary diffraction grating.

[0034] Refer again to Figure 1. The first lens array 30 is a microlens array, positioned opposite the main surface 11 of the electro-optic crystal 10. The first lens array 30 receives first parallel light L1, which has an optical axis along the direction normal to the main surface 11 of the electro-optic crystal 10, on the surface opposite to the surface facing the electro-optic crystal 10. The first parallel light L1 is, for example, laser light output from a laser diode, SLD (Super Luminescent Diode), or solid-state laser. The wavelength of the first parallel light L1 is, for example, 300 nm to 3000 nm. The optical axis of the first lens array 30 is parallel to the optical axis of the first parallel light L1. The first lens array 30 has a plurality of (three in the illustrated example) first lenses 31 arranged in a one-dimensional or two-dimensional manner. Each of the plurality of first lenses 31 corresponds to a plurality of electric field forming units 20. The first lens array 30 focuses the first parallel light L1 with each of the plurality of first lenses 31. Each of the multiple first lenses 31 is, for example, a convex lens.

[0035] The second lens array 50 is a microlens array positioned between the electro-optic crystal 10 and the first lens array 30. The optical axis of the second lens array 50 is parallel to the optical axis of the first parallel light L1. The second lens array 50 has a plurality of (three in the illustrated example) second lenses 51. Each of the plurality of second lenses 51 corresponds to each of the plurality of first lenses 31 of the first lens array 30 and is optically coupled to each of the plurality of first lenses 31. The focal length of each of the plurality of second lenses 51 is equal to the focal length of each of the plurality of first lenses 31. The second lens array 50 converts the light L2 output from each of the plurality of first lenses 31 into second parallel light L3 by each of the plurality of second lenses 51. Each of the plurality of second lenses 51 is, for example, a convex lens.

[0036] The second parallel light L3 is incident on the main surface 11 of the electro-optic crystal 10 and passes through the electro-optic crystal 10 in the thickness direction. The electro-optic crystal 10 outputs the transmitted second parallel light L3 from its back surface 12. The main surface 11 and the back surface 12 are polished to maximize the transmittance of the second parallel light L3. The light reflecting portion 13 is located on the back surface 12 side of the electro-optic crystal 10. The light reflecting portion 13 reflects the second parallel light L3 toward the main surface 11 of the electro-optic crystal 10. The light reflecting portion 13 is, for example, a dielectric multilayer film formed on the back surface 12 of the electro-optic crystal 10. If the second electrode 22 is opaque, the second electrode 22 may constitute part of the light reflecting portion 13. The second lens array 50 focuses the second parallel light L3, which has been reflected by the light reflecting portion 13 and output from the main surface 11 of the electro-optic crystal 10, by each of the multiple second lenses 51.

[0037] When the second parallel light L3 travels back and forth in the thickness direction through a region of the electro-optic crystal 10 where the refractive index undergoes a periodic change (see Figure 3(b)), the phase distribution of the second parallel light L3 changes. Therefore, when the second parallel light L3 is focused by the second lens 51, the light L4 after passing through the second lens 51 is focused to multiple focal points P1 that are separated from each other in the direction of the periodic structure of the second electrode 22 (direction D1 in the illustrated example). In contrast, when the second parallel light L3 travels back and forth in the thickness direction through a region of the electro-optic crystal 10 where the refractive index does not undergo a periodic change (see Figure 3(a)), the phase distribution of the second parallel light L3 does not change. Therefore, when the second parallel light L3 is focused by the second lens 51, the light L4 after passing through the second lens 51 is focused to a single focal point P2. In the example shown in Figure 1, of the three electric field forming sections 20 arranged along direction D1, only the two electric field forming sections 20 located at both ends form an electric field, while the electric field forming section 20 located in the center does not form an electric field.

[0038] The light shielding member 40 is positioned between the first lens array 30 and the second lens array 50. The light shielding member 40 is, for example, a metal mask. The light shielding member 40 has a plurality of regions 41, each corresponding to a plurality of electric field forming sections 20. Each of the regions 41 corresponds to a plurality of second lenses 51 and is optically coupled to the plurality of second lenses 51 on one side. Also, each of the regions 41 corresponds to a plurality of first lenses 31 and is optically coupled to the plurality of first lenses 31 on the other side. The light shielding member 40 is configured to allow light L2 focused by each of the plurality of first lenses 31 to pass through each of the plurality of regions 41, and to allow light L4 focused by each of the plurality of second lenses 51 to pass through or shield in each of the plurality of regions 41, depending on the state of the electric field of the corresponding electric field forming section 20.

[0039] In the illustrated example, each region 41 of the light shielding member 40 shields the light L4 when it is focused at a plurality of mutually separated focal points P1, in other words, when the electric field of the corresponding electric field forming unit 20 is ON, and allows the light L4 to pass through when it is focused at a single focal point P2, in other words, when the electric field of the corresponding electric field forming unit 20 is OFF. Therefore, each region 41 of the light shielding member 40 in the illustrated example has a single optical aperture 42 corresponding to a single focal point P2. When light L4 is focused at a single focal point P2, the light L4 passes through the optical aperture 42. Also, when light L4 is focused at a plurality of mutually separated focal points P1, the light L4 is shielded by the light shielding member 40 outside the optical aperture 42. The optical aperture 42 may be an opening formed in the light shielding member 40, or it may be made of a transparent material such as glass. Alternatively, the light-shielding member 40 may be configured by providing a light-shielding film on the surface of a transparent plate, such as glass, in an area excluding the optical aperture 42.

[0040] In another example, each region 41 of the light shielding member 40 may allow light L4 to pass through when it is focused at a plurality of separate focal points P1, and shield the light L4 when it is focused at a single focal point P2. In this case, each region 41 of the light shielding member 40 has an optical aperture corresponding to the plurality of focal points P1. The configuration of the optical aperture in this case may be the same as that of the optical aperture 42 described above.

[0041] The first lens array 30 converts the light L4 that has passed through the light shielding member 40 into parallel output light L5 in the first lens 31. Of the light L4 focused by the second lens array 50, the light L4 that has passed through the light shielding member 40 is converted into output light L5 by the corresponding first lens 31 and output to the outside of the optical device 1A.

[0042] The distance between the first lens array 30 and the light shielding member 40, the distance between the light shielding member 40 and the second lens array 50, and the distance between the second lens array 50 and the electro-optic crystal 10 may be equal to or different from the focal lengths of the first lens array 30 and the second lens array 50.

[0043] According to the optical device 1A of this embodiment described above, by independently controlling whether or not each of the multiple field forming units 20 forms an electric field within the electro-optic crystal 10, it is possible to freely determine, for each part, whether or not multiple parts of the second parallel light L3 corresponding to each of the multiple field forming units 20 pass through the light shielding member 40. Furthermore, by switching the field forming units 20 that form the electric field, the arrangement pattern of the output light L5 in a plane perpendicular to the optical axis can be freely switched at high speeds, for example, on the order of kHz.

[0044] Figures 4(a), (b), and (c) are schematic diagrams illustrating examples of switching the output light L5. Figure 4(a) shows the emission position of the output light L5 when light L4 passes only through the outermost region 41 of the three regions 41 shown in Figure 1, and is shielded in the other two regions 41. Figure 4(b) shows the emission position of the output light L5 when light L4 passes only through the central region 41 of the three regions 41 shown in Figure 1, and is shielded in the other two regions 41. Figure 4(c) shows the emission position of the output light L5 when light L4 is shielded only in the central region 41 of the three regions 41 shown in Figure 1, and passes through the other two regions 41. Note that light L4 may also be allowed to pass through all of the multiple regions 41. Thus, with the optical device 1A of this embodiment, the arrangement pattern of the output light L5 in a plane perpendicular to the optical axis can be freely switched.

[0045] As shown in the illustrated example, when the number of electric field forming units 20 is 3, a total of 7 arrangement patterns can be realized: 3 arrangement patterns of output light L5 that pass through only one region 41, 3 arrangement patterns of output light L5 that pass through two regions 41, and 1 arrangement pattern of output light L5 that passes through all regions 41. When the number of electric field forming units 20 is m, the number of possible arrangement patterns is expressed by the following formula (1).

number

[0046] As in this embodiment, each of the multiple electric field forming sections 20 may have a first electrode 21 provided on the main surface 11 and a second electrode 22 provided on the back surface 12. The second electrode 22 may also include a periodic structure. In that case, a configuration in which a periodic electric field is formed within the electro-optic crystal 10 while the main surface 11 of the electro-optic crystal 10 receives second parallel light L3 can be easily realized.

[0047] As in this embodiment, the second electrode 22 may be comb-shaped. In that case, the number of connection points between the second electrode 22, which includes a periodic structure, and the wiring for applying voltage to the second electrode 22 (for example, the terminal 62 shown in Figure 5) can be reduced, thus simplifying the structure for applying voltage to the second electrode 22.

[0048] As in this embodiment, each of the multiple regions 41 of the light shielding member 40 may be configured to allow light L4 focused by each of the multiple second lenses 51 to pass through when the electric field of the corresponding electric field forming unit 20 is in the off state, and to shield it when the electric field of the corresponding electric field forming unit 20 is in the on state. When the electric field of the electric field forming unit 20 is in the on state, a periodic refractive index distribution is generated within the electro-optic crystal 10, and the phase distribution of the second parallel light L3 changes. When output light L5 is generated from the second parallel light L3, the phase distribution remains in the output light L5, and the optical elements placed downstream of the optical device 1A are affected by this phase distribution. In contrast, when the electric field of the electric field forming unit 20 is in the off state, the refractive index distribution within the electro-optic crystal 10 does not change, and the phase distribution of the second parallel light L3 does not change. Therefore, each of the multiple regions 41 of the light shielding member 40 is configured to allow the light L4 focused by the second lens 51 to pass through when the electric field of the electric field forming unit 20 is in the off state, thereby reducing the influence on optical elements placed downstream of the optical device 1A.

[0049] In addition, an acoustic optic deflector (AOD), which is an acoustic-optic element, is a device that has a similar function to the optical device 1A of this embodiment. However, with an AOD, the optical system becomes complex and high adjustment technology is required because the optical axis changes. The optical device 1A of this embodiment only needs to be positioned so that the main surface 11 of the electro-optic crystal 10 is perpendicular to the optical axis of the first parallel light L1, and since the optical axis does not change, it is useful in combination with other devices (for example, a spatial light modulator).

[0050] Here, Figure 5 is a perspective view showing an example of a method for supplying voltage to the first electrode 21 and the second electrode 22. As shown in Figure 5, the optical device 1A may further include a wiring board 60 on which the electro-optic crystal 10 is mounted. In the illustrated example, the wiring board 60 faces the back surface 12 of the electro-optic crystal 10. For simplification, the first lens array 30, the light shielding member 40, and the second lens array 50 are omitted from the illustration in Figure 5.

[0051] The wiring board 60 has a plurality of terminals 62 and a terminal 63. Each of the plurality of terminals 62 is electrically connected to each of the plurality of second electrodes 22. In the illustrated example, each of the plurality of terminals 62 is conductively bonded to each of the plurality of second electrodes 22 by conductive paste 64. A conductive adhesive such as solder may be used instead of conductive paste 64. The plurality of terminals 62 each supply a drive voltage to the plurality of second electrodes 22. Terminal 63 is electrically connected to the first electrode 21. In the illustrated example, terminal 63 is electrically connected to the first electrode 21 via bonding wire 65. Terminal 63 is set to, for example, a reference potential (ground potential).

[0052] The wiring board 60 is connected to another wiring board 67 via a connector-equipped wiring 66A. The wiring board 67 is equipped with multiple field forming units 20 and multiple switching elements 68, each corresponding to a plurality of switching elements 68. The wiring board 67 is also connected to a computer's I / O connection terminal (not shown) via a connector-equipped wiring 66B. The computer inputs a signal S1 that controls the operation of the multiple switching elements 68. The wiring board 67 is also connected to a DC power supply (not shown) via a connector-equipped wiring 66C. The DC power supply provides a DC power supply voltage V1 that is applied to the multiple field forming units 20. Each switching element 68 is connected to a corresponding terminal 62 via a connector-equipped wiring 66A. When each switching element 68 receives a signal S1 from the computer, it supplies the DC power supply voltage V1 to its corresponding terminal 62. This DC power supply voltage V1 is applied to the second electrode 22 connected to that terminal 62.

[0053] In the example shown in Figure 5, the wiring board 60 is mounted on a single electro-optic crystal 10, but as shown in Figure 6, the wiring board 60 may be mounted on multiple electro-optic crystals 10. In that case, by arranging the multiple electro-optic crystals 10 in a direction intersecting the direction of arrangement (direction D1) of the multiple field-forming portions 20 in each electro-optic crystal 10, the multiple field-forming portions 20 can be arranged in a two-dimensional manner.

[0054] As described above, the optical device 1A may further include a wiring board 60 on which the electro-optic crystal 10 is mounted. In that case, a drive voltage can be easily supplied to the multiple field forming units 20 through the wiring board 60. (First variation)

[0055] Figure 7 is a cross-sectional view showing the configuration of an optical device 1B according to the first modified example of the above embodiment. In the optical device 1B, the plurality of first lenses 31 are cylindrical lenses that mainly have refractive power in the direction in which the strength of the electric field changes periodically (the direction of the periodic structure of the second electrode 22, direction D1 in the illustrated example). Also, each of the plurality of second lenses 51 is also a cylindrical lens that has refractive power in the same direction. Therefore, the focal points P1 and P2 have a linear shape extending along the extending direction of the cylindrical lens (in other words, the direction that intersects both the direction of the periodic structure of the second electrode 22 and the direction of the optical axis of the second parallel light L3). The optical aperture 42 of the light shielding member 40 may be a slit extending along the extending direction of the cylindrical lens. In that case, if the wavelength of the first parallel light L1 is λ and the period of the electric field formed by the electric field forming part 20 is X, then the width of the optical aperture 42 is, for example, (λF) / X. However, in practice, the width of the optical aperture 42 may differ from (λF) / X due to the influence of the light intensity distribution and modes of the first parallel light L1.

[0056] As shown in this modified example, each of the multiple first lenses 31 and each of the multiple second lenses 51 may be a cylindrical lens that primarily exhibits refractive power in the direction in which the strength of the electric field changes periodically, and each of the multiple regions 41 may include a slit extending along the extending direction of the cylindrical lens. In this case, it is sufficient to align the focusing position of the cylindrical lens with the slit only in the direction in which the cylindrical lens primarily exhibits refractive power. Thus, the manufacturing of the optical device 1A can be simplified. (Second variation)

[0057] Figure 8 is a cross-sectional view showing the configuration of an optical device 1C according to a second modification of the above embodiment. The optical device 1C includes a plurality of electric field forming units 23 instead of the plurality of electric field forming units 20 of the above embodiment. The plurality of electric field forming units 23 are arranged in a one-dimensional or two-dimensional manner in a plane along the main surface 11 and / or back surface 12. The plurality of electric field forming units 23 form an electric field within the electro-optic crystal 10 whose strength changes periodically in the direction D1 along the main surface 11 and / or back surface 12 of the electro-optic crystal 10. The plurality of electric field forming units 23 are configured so that the state of their electric fields can be controlled independently.

[0058] In this modified example, a plurality of first electrodes 24 are provided on the main surface 11 of the electro-optic crystal 10, and a second electrode 25 is provided on the entire surface of the back surface 12 of the electro-optic crystal 10. The first electrodes 24 are transparent electrodes. The second electrodes 25 are opaque electrodes, such as metal electrodes. The second electrodes 25 also serve as the light reflecting portion 13 in this modified example by reflecting the second parallel light L3. Each of the plurality of first electrodes 21 includes a structure that is periodic in direction D1. In one example, the first electrode 21 is comb-shaped with a plurality of comb teeth arranged in direction D1. The electric field shape formed by the plurality of first electrodes 21 and the second electrodes 25 is the same as in the above embodiment.

[0059] As shown in this modified example, the first electrode provided on the main surface 11 of the electro-optic crystal 10 may be divided into multiple parts to have a periodic structure. Even in this case, the same effects and advantages as in the above embodiment can be achieved. (Second Embodiment)

[0060] Figure 9 is a cross-sectional view showing the configuration of an optical device 1D according to a second embodiment of the present disclosure. As shown in Figure 9, the optical device 1D of this embodiment comprises an electro-optic crystal 10, a light absorbing section 14, a plurality of field forming sections 20, a first lens array 30, and a light reflecting section 90. Unlike the first embodiment, the electro-optic crystal 10 receives first parallel light L1 on its main surface 11 and outputs the first parallel light L1 transmitted through the electro-optic crystal 10 from its back surface 12. In this embodiment, not only the first electrode 21 but also the second electrode 22 is a transparent electrode. The other structures of the electro-optic crystal 10 and the plurality of field forming sections 20 are the same as in the first embodiment or the second modified example. Figure 9 shows an example in which the first electrode 21 has a periodic structure, similar to the second modified example, but the second electrode 22 may have a periodic structure, similar to the first embodiment.

[0061] The first lens array 30 has a plurality of electric field forming sections 20 and a plurality of first lenses 31, each corresponding to a plurality of first lenses 31. The first lens array 30 focuses the first parallel light L1 output from the back surface 12 of the electro-optic crystal 10 using each of the plurality of first lenses 31. Each of the plurality of first lenses 31 may be a cylindrical lens that has refractive power mainly in the direction of the periodic structure of the first electrode 21 or the second electrode 22 (direction D1 in the illustrated example).

[0062] When the first parallel light L1 passes through a region of the electro-optic crystal 10 where the refractive index undergoes a periodic change, the phase distribution of the first parallel light L1 changes. Therefore, when the first parallel light L1 is focused by the first lens 31, the light L2 after passing through the first lens 31 is focused to a plurality of focal points P1 that are separated from each other in the direction of the periodic structure of the first electrode 21 (direction D1 in the illustrated example). In contrast, when the first parallel light L1 passes through a region of the electro-optic crystal 10 where the refractive index does not undergo a periodic change, there is no change in the phase distribution of the first parallel light L1. Therefore, when the first parallel light L1 is focused by the first lens 31, the light L2 after passing through the first lens 31 is focused to a single focal point P2. In the illustrated example, of the three electric field forming parts 20 arranged along direction D1, only the two electric field forming parts 20 located at both ends form an electric field, while the electric field forming part 20 located in the center does not form an electric field. Furthermore, if the first lens 31 is a cylindrical lens, the focal points P1 and P2 have a linear shape extending along the direction of extension of the cylindrical lens (in other words, the direction that intersects both the direction of the periodic structure of the first electrode 21 and the direction of the optical axis of the first parallel light L1).

[0063] The light-reflecting portion 90 faces the back surface 12 of the electro-optic crystal 10 with the first lens array 30 in between. The light-reflecting portion 90 has a plurality of regions 91, each corresponding to a plurality of electric field forming portions 20. Each of the regions 91 corresponds to a plurality of first lenses 31 and is optically coupled to each of the plurality of first lenses 31. The light-reflecting portion 90 is configured to reflect or pass through each of the regions 91 the light L2 focused by each of the plurality of first lenses 31, depending on the state of the electric field of the corresponding electric field forming portion 20.

[0064] In the illustrated example, each region 91 of the light-reflecting section 90 allows light L2 to pass through when it is focused at multiple separate focal points P1, in other words, when the electric field of the corresponding electric field forming section 20 is ON, and reflects light L2 when it is focused at a single focal point P2, in other words, when the electric field of the corresponding electric field forming section 20 is OFF. Therefore, each region 91 of the light-reflecting section 90 in the illustrated example has a single light-reflecting film 92 corresponding to a single focal point P2. When light L2 is focused at a single focal point P2, the light L2 is reflected by the light-reflecting film 92. Also, when light L2 is focused at multiple separate focal points P1, the light L2 passes outside the light-reflecting film 92. The light-reflecting film 92 is, for example, a metal film or dielectric film formed on the surface of a transparent plate 93 such as glass. If the first lens 31 is a cylindrical lens, the light-reflecting film 92 has a light-reflecting surface that extends along the extending direction of the cylindrical lens. If the wavelength of the first parallel light L1 is λ and the period of the electric field formed by the electric field forming unit 20 is X, then the width of the light-reflecting film 92 in direction D1 is, for example, (λF) / X. However, in reality, the width of the light-reflecting film 92 in direction D1 may differ from (λF) / X due to the influence of the light intensity distribution and modes of the first parallel light L1.

[0065] In another example, each region 91 of the light-reflecting section 90 may reflect light L2 when it is focused at a plurality of separate focal points P1, and allow light L2 to pass through when it is focused at a single focal point P2. In this case, each region 91 of the light-reflecting section 90 has a light-reflecting film corresponding to the plurality of focal points P1. The configuration of the light-reflecting film in this case may be the same as that of the light-reflecting film 92 described above.

[0066] The light-absorbing section 14 is positioned on the opposite side of the light-reflecting section 90 from the electro-optic crystal 10 and the first lens array 30. In other words, the light-reflecting section 90 is positioned between the first lens array 30 and the light-absorbing section 14. The light-absorbing section 14 is configured to absorb light L2 that has passed through the light-reflecting section 90. The light-absorbing section 14 has multiple regions, each corresponding to a plurality of regions 91 of the light-reflecting section 90. The light-absorbing section 14 includes a light-absorbing material, such as chromium.

[0067] The first lens array 30 converts the light L2 reflected by the light reflection section 90 into parallel output light L5 in the first lens 31. Of the light L2 focused by the first lens array 30, the light L2 reflected by the light reflection section 90 is converted into output light L5 by the corresponding first lens 31 and output to the outside of the optical device 1D. Of the light L2 focused by the first lens array 30, the light L2 that passes through the light reflection section 90 is absorbed and annihilated by the light absorption section 14.

[0068] The distance between the electro-optic crystal 10 and the first lens array 30, and the distance between the first lens array 30 and the light reflecting portion 90, may be equal to or different from the focal lengths of the first lens array 30 and the second lens array 50.

[0069] According to the optical device 1D of this embodiment described above, by independently controlling whether or not each of the multiple field forming units 20 forms an electric field within the electro-optic crystal 10, it is possible to freely determine, for each part, whether or not multiple parts of the first parallel light L1 corresponding to each of the multiple field forming units 20 are reflected by the light reflection unit 90. Furthermore, by switching the field forming units 20 that form the electric field, the arrangement pattern of the output light L5 in a plane perpendicular to the optical axis can be freely switched at high speeds, for example, on the order of kHz.

[0070] As in this embodiment, each of the multiple electric field forming sections 20 may have a first electrode 21 which is a transparent electrode provided on the main surface 11 and a second electrode 22 which is a transparent electrode provided on the back surface 12. Furthermore, one or both of the first electrode 21 and the second electrode 22 may include a periodic structure. In that case, a configuration in which the first parallel light L1 and the output light L5 pass through the electro-optic crystal 10 while a periodic electric field is formed within the electro-optic crystal 10 can be easily realized.

[0071] As in this embodiment, the first electrode 21 or the second electrode 22 may be comb-shaped. In that case, the number of connection points between the first electrode 21 or the second electrode 22, which includes a periodic structure, and the wiring for applying voltage to the first electrode 21 or the second electrode 22 (for example, the terminal 62 shown in Figure 5) can be reduced, thus simplifying the structure for applying voltage to the first electrode 21 or the second electrode 22.

[0072] As in this embodiment, each of the multiple regions 91 of the light reflection section 90 may be configured to reflect the light L2 focused by each of the multiple first lenses 31 when the electric field of the corresponding electric field forming section 20 is off, and to allow it to pass through when the electric field of the corresponding electric field forming section 20 is on. When the electric field of the electric field forming section 20 is on, a periodic refractive index distribution is generated within the electro-optic crystal 10, and the phase distribution of the first parallel light L1 changes. When output light L5 is generated from the first parallel light L1, this phase distribution remains in the output light L5 as well. In addition, the phase distribution of the output light L5 also changes when the output light L5 passes through the electro-optic crystal 10. Therefore, optical elements placed downstream of the optical device 1D are affected by these phase distributions. In contrast, when the electric field of the electric field forming section 20 is off, the refractive index distribution within the electro-optic crystal 10 does not change, and the phase distributions of the first parallel light L1 and the output light L5 do not change. Therefore, each of the multiple regions 91 of the light reflection section 90 is configured to reflect the light L2 focused by the first lens 31 when the electric field of the electric field forming section 20 is in the off state, thereby reducing the influence on optical elements placed downstream of the optical device 1D.

[0073] The optical device 1D of this embodiment may also further include the wiring board 60 shown in Figure 5 or Figure 6. In that case, the drive voltage can be easily supplied to the multiple electric field forming units 20 through the wiring board 60. Furthermore, the wiring board 60 used in this embodiment may further have an optical aperture. The optical aperture is formed at a position opposite to the electro-optic crystal 10 and allows the first parallel light L1 and the output light L5 to pass through. The optical aperture may be an aperture formed in the wiring board 60, or it may be made of a transparent material such as glass. Alternatively, the wiring board 60 itself may be made of a transparent material such as glass. In that case, the optical aperture is not necessary.

[0074] As mentioned above, each of the multiple first lenses 31 may be a cylindrical lens that primarily has refractive power in the direction in which the strength of the electric field changes periodically, and each of the multiple regions 91 may include a light-reflecting surface that extends along the extending direction of the cylindrical lens. In that case, it is sufficient to align the focusing position of the cylindrical lens with the light-reflecting surface only in the direction in which the cylindrical lens primarily has refractive power. Thus, the manufacturing of the optical device 1D can be simplified. (Third embodiment)

[0075] Figure 10 is a schematic diagram showing the configuration of an optical device 70A according to a third embodiment of this disclosure. The optical device 70A of this embodiment comprises the optical device 1A of the first embodiment, a light source 71, a mirror 72, an objective lens 73, a mirror 74, a focusing lens 75, an imaging unit 76, a control unit 77, an I / O controller 78, a polarizing plate 84, a polarizing beam splitter 85, and a quarter-wave plate 86. Note that the optical device 70A may also include the optical device 1B of the first modified example, the optical device 1C of the second modified example, or the optical device 1D of the second embodiment instead of the optical device 1A of the first embodiment.

[0076] The light source 71 outputs a first parallel light L1. The light source 71 includes, for example, a laser diode, an SLD, or a solid-state laser. One surface of the polarizing plate 84 is optically coupled to the light source 71, making the first parallel light L1 output from the light source 71 linearly polarized. The polarizing beam splitter 85 is optically coupled to the other surface of the polarizing plate 84 and the optical device 1A, and guides the linearly polarized first parallel light L1 to the optical device 1A by transmitting or reflecting it.

[0077] The quarter-wave plate 86 is positioned in the optical path between the polarizing beam splitter 85 and the optical device 1A. The linearly polarized first parallel light L1 is converted to circular polarization by the quarter-wave plate 86 and then input to the optical device 1A. The output light L5 output from the optical device 1A is also converted to linear polarization by the quarter-wave plate 86, having a polarization direction perpendicular to the polarization direction of the first parallel light L1. The polarizing beam splitter 85 separates the linearly polarized output light L5 from the first parallel light L1 by reflecting or transmitting it. With this configuration, the output light L5 can be separated and extracted from the first parallel light L1 while suppressing a decrease in the light intensity of the output light L5.

[0078] Mirror 72 is, for example, a half-mirror or a dielectric mirror, and transmits the output light L5 extracted by the polarizing beam splitter 85. The objective lens 73 focuses the output light L5 that has passed through mirror 72 toward the illumination surface B1 of object B. The illumination surface B1 receives the light L6 focused by the objective lens 73 and generates light L7. For example, light L7 is scattered light from the illumination surface B1. Alternatively, if output light L5 and light L6 are excitation light, light L7 is fluorescence emitted from the excited object B. Light L7 is made into parallel light L8 by the objective lens 73. Parallel light L8 is separated from output light L5 by reflection at mirror 72. After being reflected by mirror 74, parallel light L8 is focused toward the imaging unit 76 by the focusing lens 75. The imaging unit 76 captures the light L9 focused by the focusing lens 75 and generates imaging data.

[0079] In the illustrated example, two output beams L5 are focused and irradiated onto the target surface B1. In this case, on surfaces other than the irradiated surface B1, which is the focusing surface, interference fringes are formed by the interference of the two beams L6. These interference fringes can be used as structured illumination. Alternatively, three output beams L5 that are not aligned in a line may be focused and irradiated onto the target surface B1. In that case, the three beams L6 interfere with each other, forming a grid of light spots. These grid of light spots can also be used as structured illumination.

[0080] The I / O controller 78 is electrically connected to the optical device 1A and applies a drive voltage to the multiple electric field forming sections 20 of the optical device 1A. The I / O controller 78 is electrically connected to the control unit 77 and controlled by the control unit 77. The I / O controller 78 includes, for example, a wiring board 67 and multiple switching elements 68 as shown in Figure 5. The control unit 77 provides, for example, the signal S1 shown in Figure 5 to the I / O controller 78. The control unit 77 is a computer such as a personal computer, a smart device such as a smartphone or tablet terminal, or a cloud server. The computer as the control unit 77 has an HDD, a storage device such as flash memory or RAM, and a processor (CPU). The control unit 77 may be configured as a microcontroller or an FPGA (Field-Programmable Gate Array).

[0081] According to the optical device 70A of this embodiment, by including the optical device 1A, the arrangement pattern of the output light L5 in a plane perpendicular to the optical axis can be switched quickly and freely. Therefore, the shape of the irradiation area of ​​the light L6 irradiated onto the target surface B1 can be switched quickly and freely. (Fourth Embodiment)

[0082] Figure 11 is a schematic diagram showing the configuration of an optical device 70B according to the fourth embodiment of this disclosure. The optical device 70B of this embodiment comprises the optical device 1A of the first embodiment, a light source 71, a mirror 72, an objective lens 73, mirrors 74a, 74b and 74c, a focusing lens 75, an imaging unit 76, a control unit 79, an SLM controller 80, a spatial light modulator (SLM) 81, a polarizing plate 84, a polarizing beam splitter 85, and a quarter-wave plate 86. Note that the optical device 70B may also include the optical device 1B of the first modification, the optical device 1C of the second modification, or the optical device 1D of the second embodiment instead of the optical device 1A of the first embodiment. The first parallel light L1 output from the light source 71 is a coherent laser light with spatially aligned phase. The configuration of the polarizing plate 84, the polarizing beam splitter 85, and the quarter-wave plate 86 is the same as that of the optical device 70C of the third embodiment described above.

[0083] Mirrors 74a and 74b guide the output light L5, extracted by the polarizing beam splitter 85, to the SLM 81 by reflecting it. The SLM 81 is a liquid crystal type SLM. The SLM 81 has multiple pixels and receives the output light L5, modulating the phase of the output light L5 pixel by pixel. The SLM 81 may be reflective or transmissive. Mirror 72 is, for example, a half mirror or a dielectric mirror, and transmits the modulated output light L5 output from the SLM 81. The objective lens 73 focuses the output light L5 that has passed through the mirror 72 toward the illumination target surface B1 of object B. The illumination target surface B1 receives the light L6 focused by the objective lens 73 and generates light L7. For example, light L7 is scattered light on the illumination target surface B1. Alternatively, if the output light L5 and light L6 are excitation light, light L7 is fluorescence emitted from the excited object B. Light L7 is converted into parallel light L8 by the objective lens 73. After being reflected by the mirror 74, the parallel light L8 is focused toward the imaging unit 76 by the condensing lens 75. The imaging unit 76 captures the light L9 focused by the condensing lens 75 and generates imaging data.

[0084] The SLM controller 80 is electrically connected to the SLM 81 and provides the SLM 81 with a signal indicating a modulation pattern. The SLM controller 80 is also electrically connected to the optical device 1A and applies a drive voltage to the multiple field-forming units 20 of the optical device 1A. Furthermore, the SLM controller 80 is electrically connected to the imaging unit 76 and provides the imaging unit 76 with a trigger signal indicating the imaging timing. The SLM controller 80 is electrically connected to the control unit 79 and controlled by the control unit 79. The SLM controller 80 includes, for example, a wiring board 67 and multiple switching elements 68 as shown in Figure 5. The control unit 79 controls the state of the electric fields of the multiple field-forming units 20 and the modulation pattern of the SLM 81. The control unit 79 provides, for example, the signal S1 shown in Figure 5 to the SLM controller 80. The control unit 79 is a computer such as a personal computer, a smart device like a smartphone or tablet terminal, or a cloud server. The computer acting as the control unit 79 includes an HDD, a storage device such as flash memory or RAM, and a processor (CPU). The control unit 79 may be configured using a microcontroller or an FPGA (Field-Programmable Gate Array).

[0085] The SLM81 has multiple modulation regions, each corresponding to one of the multiple field forming sections 20 of the optical device 1A. Each modulation region presents a distinct modulation pattern. The modulation pattern may be, for example, a two-beam interference pattern necessary for structured illumination, or a multi-beam interference pattern showing a lattice pattern. In this case, multiple (e.g., 5x5 or 1x5) light points are formed on the illuminated surface B1, distributed in a two-dimensional manner. The arrangement and number of light points formed may differ for each modulation region. Thus, by presenting a distinct modulation pattern in each modulation region, the illumination pattern on the illuminated surface B1 changes in accordance with the switching of the output light L5 arrangement pattern.

[0086] For the sake of explanation, let's assume that the optical device 1A has 3 rows and 3 columns (a total of 9) of electric field forming units 20. Figure 12 shows the optical modulation surface of the SLM81 in this case. As shown in Figure 12, the SLM81 has the same number of modulation regions M(1) to M(9) as the electric field forming units 20. The modulation regions M(1) to M(9) are arranged in 3 rows and 3 columns, similar to the electric field forming units 20. The modulation regions M(1) to M(9) correspond one-to-one with the 9 electric field forming units 20. Output light L5, which has passed through the corresponding electric field forming unit 20 and is output from the optical device 1A, is incident on each of the 9 modulation regions M(1) to M(9) and modulated. The control unit 79 controls the voltage applied to the 9 electric field forming units 20 so that the output light L5 is sequentially incident on the modulation regions M(1) to M(9) and modulated. Then, after the output light L5 has finished entering the modulation regions M(1) to M(9), the control unit 79 updates the modulation pattern of the SLM 81 via the SLM controller 80. Subsequently, the control unit 79 controls the voltage applied to the nine field forming units 20 again, so that the output light L5 is sequentially entered and modulated in the modulation regions M(1) to M(9). The optical device 70B repeats this operation.

[0087] Figure 13 is a flowchart illustrating the operation of the optical device 70B. As shown in Figure 13, first, the control unit 79 sets the modulation pattern of the SLM 81 through the SLM controller 80 (step ST1). This modulation pattern includes individual modulation patterns for each of the multiple modulation regions M(1) to M(9). Next, the control unit 79 controls the nine field forming units 20 through the SLM controller 80 to inject the output light L5 into the modulation region M(1) (step ST2). Then, the control unit 79 provides the imaging unit 76 with a trigger signal indicating the imaging timing through the SLM controller 80 (step ST3). After that, the process returns to step ST2, injecting the output light L5 into the modulation region M(2), and performing step ST3 again. In this way, the output light L5 is sequentially injected into all modulation regions M(1) to M(9), and step ST3 is performed each time. After the output light L5 has been incident on all modulation regions M(1) to M(9) (step ST4: YES), the process returns to step ST1 and the modulation pattern of the SLM81 is updated. This modulation pattern includes individual modulation patterns for each of the multiple modulation regions M(1) to M(9). Then, steps ST2 to ST4 are repeated again. After all the pre-prepared modulation patterns have been presented (step ST5: YES), the optical device 70B terminates its operation.

[0088] The effects obtained by the optical device 70B of this embodiment are as follows. In a liquid crystal type SLM81, an electric field is individually formed inside the liquid crystal layer by each of the multiple electrodes. However, there is a problem that the speed of modulation pattern switching is impaired because the response of the liquid crystal is delayed in response to the time change of the electric field inside the liquid crystal layer. In this embodiment, the optical modulation surface of the SLM81 is divided into multiple modulation regions M(1) to M(9), and output light L5 is sequentially input to each of the multiple modulation regions M(1) to M(9) using the optical device 1A. This makes it possible to speed up the switching of modulation patterns at the expense of resolution. The optical device 70B can be applied to observation of high-speed phenomena or to optical tweezers or atomic trapping techniques that require a high frame rate, by controlling holographic light at a high rate.

[0089] In the above explanation, the modulation pattern of the SLM81 is updated after the output light L5 has been injected into all modulation regions M(1) to M(9). However, the modulation pattern of the SLM81 may be divided into two or more regions (for example, three regions), and the modulation pattern may be updated for each region. Figure 14 is a timing chart showing an example of such operation. In Figure 14, line G1 represents the period during which the output light L5 is injected into modulation regions M(1) to M(9). In the section where line G1 is high level, the output light L5 is injected into one of the modulation regions, and the number attached near line G1 represents the number i of the modulation region M(i) into which the output light L5 is injected. Line G2 represents the period during which the modulation patterns of modulation regions M(1) to M(3) are presented. In the section T1 where line G2 is high level, the modulation patterns of modulation regions M(1) to M(3) are presented. Line G3 represents the period during which the modulation patterns of modulation regions M(4) to M(6) are presented. In section T2, where line G3 is at a high level, the modulation pattern of modulation region M(4) to M(6) is presented. Line G4 represents the period during which the modulation pattern of modulation region M(7) to M(9) is presented. In section T3, where line G4 is at a high level, the modulation pattern of modulation region M(7) to M(9) is presented.

[0090] Furthermore, because the response of the liquid crystal layer is delayed, for example, when presenting the modulation pattern of modulation regions M(1) to M(3) in section T1, the application of voltage to the electrodes of modulation regions M(1) to M(3) begins at timing t1, which is before section T1. Then, after ending the application of voltage to the electrodes at the end of section T1, the presentation of the modulation pattern completely ends at timing t2, which is after section T1. The same applies when presenting the modulation pattern of modulation regions M(4) to M(6) in section T2, and when presenting the modulation pattern of modulation regions M(7) to M(9) in section T3.

[0091] In this way, by dividing the modulation pattern of the SLM81 into two or more regions and updating the modulation pattern for each region, it becomes possible to repeatedly inject the output light L5 into modulation regions M(1) to M(9) without being affected by the response time of the liquid crystal layer, as shown in the timing chart of Figure 14. Therefore, the switching of the modulation pattern can be made even faster. (Fifth embodiment)

[0092] Figure 15 is a schematic diagram showing the configuration of the optical device 70C according to the fifth embodiment of this disclosure. The optical device 70C of this embodiment further includes an SLM controller 82 and an SLM 83 in addition to the configuration of the optical device 70B of the fourth embodiment. Furthermore, the imaging unit 76 of this embodiment has a rolling shutter method that sequentially detects light from multiple light incident regions aligned in one direction.

[0093] The SLM controller 82 is electrically connected to the SLM 83 and provides the SLM 83 with a signal indicating a modulation pattern. The SLM controller 82 is electrically connected to the control unit 79 and controlled by the control unit 79. The control unit 79 controls the modulation pattern presented to the SLM 83 through the SLM controller 82. The modulation pattern presented to the SLM 83 causes the focused image of light L9 by the focusing lens 75 to form at multiple positions. The focused images of light L9 at each position are identical to each other. Since the imaging unit 76 has a rolling shutter system, the imaging unit 76 sequentially captures the focused images of light L9 formed at each position with equal time differences. This allows the focused images of light L9 to be captured at a rate faster than the imaging unit 76's original frame rate.

[0094] The optical devices and optical apparatuses according to this disclosure are not limited to the embodiments described above, and various other modifications are possible. For example, in the first embodiment described above, the second electrode 22 has a structure in which it is periodic in direction D1, and the first electrode 21 is formed over the entire surface of the back surface 12. In the second modified example described above, the first electrode 21 has a structure in which it is periodic in direction D1, and the second electrode 22 is formed over the entire surface of the back surface 12. The invention is not limited to these forms, and may include a structure in which both the first electrode 21 and the second electrode 22 are periodic in direction D1. In that case, both the first electrode 21 and the second electrode 22 may be comb-shaped. Figure 16 is a schematic diagram showing the state inside the electro-optic crystal 10 when (a) no electric field is formed and (b) an electric field is formed in such an embodiment. As shown in Figure 16(b), even in such an embodiment, when an electric field is formed between the first electrode 21 and the second electrode 22, the refractive index of the region A1 in which the electric field is formed changes instantaneously with respect to other regions within the electro-optic crystal 10. As a result, in the region inside the electro-optic crystal 10 corresponding to the electric field forming portion 20, the refractive index changes periodically and instantaneously along direction D1. Furthermore, when both the first electrode 21 and the second electrode 22 have a structure that is periodic in direction D1, the spread of the electric field in direction D1 can be suppressed compared to when either the first electrode 21 or the second electrode 22 is formed over the entire surface of the main surface 11 or the back surface 12. Thus, a periodic refractive index distribution can be formed in a more orderly manner.

[0095] Furthermore, in the first embodiment, the direction of the period in the periodic structure of the multiple second electrodes 22 coincides with each other among the multiple second electrodes 22. The embodiment is not limited to this form, and the direction of the period in the periodic structure of at least one second electrode 22 may differ from the direction of the period in the periodic structure of the other second electrodes 22. Similarly, in the second modified example, the direction of the period in the periodic structure of the multiple first electrodes 21 coincides with each other among the multiple first electrodes 21. The embodiment is not limited to this form, and the direction of the period in the periodic structure of at least one first electrode 21 may differ from the direction of the period in the periodic structure of the other first electrodes 21.

[0096] Furthermore, in the above embodiment, a comb shape is exemplified as the shape of the first electrode 21 or the second electrode 22. The electric field forming unit that forms an electric field of periodically changing strength within the electro-optic crystal 10 is not limited to this form. For example, the electric field forming unit may have a plurality of electrodes arranged in two dimensions, in which case a voltage may be selectively applied to a part of the plurality of electrodes in order to form an electric field of periodically changing strength. Alternatively, one of the first electrode 21 and the second electrode 22 may be comb-shaped (or another form that can form an electric field of periodically changing strength within the electro-optic crystal 10), and the other electrode may be a form having a plurality of electrodes arranged in two dimensions. In that case, the other electrode may be used to form an electric field in order to correct the refractive index distribution caused by variations in the electro-optic effect within the electro-optic crystal 10 to a desired distribution (e.g., a uniform distribution).

[0097] Furthermore, the electrodes described as being composed of transparent electrodes in the above embodiments may be composed of opaque electrodes (e.g., metal electrodes). In that case, the electrodes may have a structure (e.g., an opening) through which light can pass. [Explanation of symbols]

[0098] 1A~1D...Optical device, 10...Electro-optic crystal, 11...Main surface, 12...Back surface, 13...Light reflecting part, 14...Light absorbing part, 20...Field forming part, 21...First electrode, 22...Second electrode, 30...First lens array, 31...First lens, 40...Light shielding member, 41...Region, 42...Optical aperture, 50...Second lens array, 51...Second lens, 60...Wiring board, 62,63...Terminals, 64...Conductive paste, 65...Bonding wire, 66A,66B,66C...Wiring with connector, 67...Wiring board, 68...Switching element, 70A,70B,70C...Optical device, 71...Light source, 72...Mirror, 73...Objective lens Z, 74, 74a, 74b, 74c…Mirror, 75…Focusing lens, 76…Imaging unit, 77, 79…Control unit, 78…I / O controller, 80, 82…SLM controller, 81, 83…Spatial light modulator (SLM), 84…Polarizer, 85…Polarizing beam splitter, 86…Quarter wave plate, 90…Light reflecting unit, 91…Region, A1…Region, B…Object, B1…Irradiation target surface, D1…Direction, L1…First parallel light, L2, L4, L6, L7, L9…Light, L3…Second parallel light, L5…Output light, L8…Parallel light, M(1)~M(9), M(i)…Modulation region, P1, P2…Focusing point, S1…Signal, V1…DC power supply voltage.

Claims

1. A first lens array having a plurality of first lenses arranged in a one-dimensional or two-dimensional manner, which focuses first parallel light with each of the plurality of first lenses, A second lens array having a plurality of second lenses corresponding to each of the plurality of first lenses, which converts the light output from each of the plurality of first lenses into second parallel light by each of the plurality of second lenses, A plate-shaped electro-optic crystal having a main surface and a back surface, the main surface receiving the second parallel light, A light-reflecting portion is provided on the back side of the electro-optic crystal and reflects the second parallel light toward the main surface, A plurality of electric field forming units are arranged corresponding to each of the plurality of second lenses, forming an electric field within the electro-optic crystal whose strength periodically changes in a direction along the main surface or the back surface, and the state of the electric field can be controlled independently of each other. A light-shielding member disposed between the first lens array and the second lens array, Equipped with, The second lens array collects the second parallel light, which has been reflected by the light reflecting portion and output from the main surface of the electro-optic crystal, using each of the plurality of second lenses. The light shielding member has a plurality of regions corresponding to the plurality of electric field forming portions, and is configured to allow light focused by each of the plurality of first lenses to pass through each of the plurality of regions, and to allow light focused by each of the plurality of second lenses to pass through or shield in each of the plurality of regions according to the state of the electric field of the corresponding electric field forming portion. The first lens array is an optical device that converts the light, which has been focused by the second lens and then passed through the light shielding member, into parallel output light using the first lens.

2. Each of the aforementioned plurality of electric field forming units is: The first electrode provided on the main surface, The second electrode provided on the back surface, It has, The first electrode is a transparent electrode, The optical device according to claim 1, comprising a structure in which one or both of the first electrode and the second electrode are periodic in the aforementioned direction.

3. The optical device according to claim 2, wherein one or both of the first electrode and the second electrode are comb-shaped.

4. The optical device according to claim 1 or 2, wherein each of the plurality of regions of the light shielding member is configured to allow the light focused by each of the plurality of second lenses to pass through when the electric field of the corresponding electric field forming portion is in the off state, and to shield it when the electric field of the corresponding electric field forming portion is in the on state.

5. Each of the plurality of first lenses and each of the plurality of second lenses is a cylindrical lens that has refractive power mainly in the aforementioned direction. The optical device according to claim 1 or 2, wherein each of the plurality of regions includes a slit extending along the extending direction of the cylindrical lens.

6. A plate-shaped electro-optic crystal having a main surface and a back surface, the main surface receiving first parallel light and the back surface outputting the first parallel light, A plurality of electric field forming units are arranged in a one-dimensional or two-dimensional manner within a plane along the main surface or the back surface of the electro-optic crystal, forming an electric field within the electro-optic crystal whose strength periodically changes in the direction along the main surface or the back surface, and the state of the electric field can be controlled independently of each other. A first lens array having a plurality of electric field forming sections and a plurality of first lenses corresponding to each of them, which focuses the first parallel light output from the back surface of the electro-optic crystal by each of the plurality of first lenses, A light reflecting unit having a plurality of regions corresponding to each of the plurality of electric field forming units, configured to reflect or pass light focused by each of the plurality of first lenses in each of the plurality of regions according to the state of the electric field of the corresponding electric field forming unit, A light absorbing section configured to absorb the light that has passed through the light reflecting section, Equipped with, The first lens array is an optical device that converts the light reflected by the light reflecting portion into parallel output light using the first lens, and the electro-optic crystal transmits the output light.

7. Each of the aforementioned plurality of electric field forming units is: The first electrode provided on the main surface, The second electrode provided on the back surface, It has, The first electrode and the second electrode are transparent electrodes. The optical device according to claim 6, comprising a structure in which one or both of the first electrode and the second electrode are periodic in the aforementioned direction.

8. The optical device according to claim 7, wherein one or both of the first electrode and the second electrode are comb-shaped.

9. The optical device according to claim 6 or 7, wherein each of the plurality of regions of the light reflecting portion is configured to reflect light focused by each of the plurality of first lenses when the electric field of the corresponding electric field forming portion is in the off state, and to allow light to pass through when the electric field of the corresponding electric field forming portion is in the on state.

10. Each of the aforementioned plurality of first lenses is a cylindrical lens that has refractive power mainly in the aforementioned direction. The optical device according to claim 6 or 7, wherein each of the plurality of regions includes a light-reflecting surface extending along the extending direction of the cylindrical lens.

11. The wiring board further comprises the aforementioned electro-optic crystal, The optical device according to claim 1 or 6, wherein the wiring board is electrically connected to each of the plurality of electric field forming units and has a plurality of terminals for supplying each of the plurality of electric field forming units with a drive voltage.

12. The optical device according to claim 1 or 6, wherein the electro-optic crystal includes a KTN crystal.

13. The optical device according to claim 1 or 6, A liquid crystal spatial light modulator that receives the output light output from the optical device and modulates the phase of the output light pixel by pixel, Equipped with, The spatial light modulator is an optical device having a plurality of modulation regions corresponding to the plurality of electric field forming portions of the optical device.

14. The system further comprises a control unit that controls the state of the electric field in the plurality of electric field forming units and the modulation pattern of the spatial light modulator, The optical apparatus according to claim 13, wherein the control unit controls the plurality of electric field forming units so that the output light is sequentially incident on the plurality of modulation regions, and updates the modulation pattern after the output light has finished incident on the plurality of modulation regions.

15. The optical device according to claim 1 or 6, The light source that outputs the first parallel light, A polarizing plate that linearly polarizes the first parallel light output from the light source, A polarization beam splitter that guides the first parallel light, which is linearly polarized, to the optical device by transmitting or reflecting the first parallel light, A quarter-wave plate is placed in the optical path between the polarizing beam splitter and the optical device, Equipped with, The polarizing beam splitter is an optical device that reflects or transmits the output light that is output from the optical device and has passed through the quarter-wave plate.

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