Optical device and optical apparatus

Abstract

In this optical device (1), a first lens array (30) condenses first parallel light (L1) by means of a plurality of first lenses (31). The second lens array (50) converts the light outputted from the plurality of first lenses (31) into second parallel light. The electro-optical crystal (10) receives the second parallel light on the main surface. The light reflecting portion is disposed on the rear surface side of the electro-optical crystal. The plurality of electric field forming units (20) form an electric field having periodically varying intensity within the electro-optical crystal. The second lens array (50) condenses the second parallel light (L3) output from the electro-optical crystal (10) by means of a plurality of second lenses. The light shielding members (40) allow the light focused by the plurality of second lenses (51) to pass through or shield the light in the plurality of regions in accordance with the state of the electric field of the corresponding electric field forming unit (20).

Description

Technical Field

[0001] The present invention relates to an optical device and an optical apparatus. This application claims the benefit of priority based on Japanese Application No. 2022-205715 filed on December 22, 2022, the entire contents of which are incorporated herein by reference. Background Art

[0002] Patent Documents 1 to 7 disclose optical modulators. These optical modulators include an electro-optical crystal and multiple electrodes that independently generate an electric field within the electro-optical crystal. The electro-optical crystal is, for example, a perovskite-type electro-optical crystal with a relative dielectric constant of 1000 or greater. Examples of the electro-optical crystal are KTN, KLTN, or PLZT. Prior art literature Patent Literature

[0003] Patent Document 1: International Publication No. 2017 / 213098 Patent Document 2: International Publication No. 2017 / 213099 Patent Document 3: International Publication No. 2017 / 213100 Patent Document 4: International Publication No. 2017 / 213101 Patent Document 5: International Publication No. 2019 / 111332 Patent Document 6: International Publication No. 2019 / 111333 Patent Document 7: International Publication No. 2019 / 111334 Summary of the Invention Technical problem to be solved by the invention

[0004] An optical device using a crystal that can switch the configuration pattern of parallel light in a plane perpendicular to the optical axis at high speed and freely is effective. As an example, a combination of such an optical device and a spatial light modulator can be cited. That is, a spatial light modulator is used when modulating the phase of light in space. Among spatial light modulators, in addition to the spatial light modulators with electro-optical crystals listed in Patent Documents 1 to 7, there are also spatial light modulators with a liquid crystal layer (liquid crystal spatial light modulator). In a liquid crystal spatial light modulator, an electric field is formed separately inside the liquid crystal layer by a plurality of electrodes. However, in a liquid crystal spatial light modulator, since the response of the liquid crystal is delayed relative to the time change of the electric field inside the liquid crystal layer, there is a problem that the high speed of switching the modulation pattern is impaired. Therefore, for example, by dividing the modulation area of the liquid crystal spatial light modulator into a plurality of areas and using the optical device as described above to sequentially input parallel light into each of the plurality of areas, it is possible to speed up the switching of the modulation pattern at the expense of resolution.

[0005] An object of the present invention is to provide an optical device capable of freely switching the arrangement pattern of parallel light in a plane perpendicular to the optical axis at high speed, and an optical apparatus capable of increasing the speed of switching the modulation pattern. Technical means for solving technical problems

[0006] [1] The optical device of the present invention comprises a first lens array, a second lens array, a plate-shaped electro-optical crystal, a light reflecting portion, a plurality of electric field forming portions, and a light shielding member. The first lens array comprises a plurality of first lenses arranged in a one-dimensional or two-dimensional manner, and is configured to focus first parallel light rays respectively through the plurality of first lenses. The second lens array comprises a plurality of second lenses corresponding to the plurality of first lenses, and is configured to convert light rays respectively outputted from the plurality of first lenses into second parallel light rays respectively through the plurality of second lenses. The electro-optical crystal has a principal surface and a back surface, and is configured to receive the second parallel light rays on the principal surface. The light reflecting portion is arranged on the back surface side of the electro-optical crystal, and is configured to reflect the second parallel light rays toward the principal surface. The plurality of electric field forming portions are arranged corresponding to the plurality of second lenses, respectively. The plurality of electric field forming portions form electric fields whose intensities periodically change in the direction along the principal surface or the back surface in the electro-optical crystal, and are configured to be able to control the state of the electric fields independently of each other. The second lens array focuses the second parallel light rays respectively reflected by the light reflecting portion and outputted from the principal surface of the electro-optical crystal through the plurality of second lenses. The light shielding member is arranged between the first lens array and the second lens array. The light shielding member includes a plurality of regions corresponding to the plurality of electric field forming sections, and is configured to allow light focused by the plurality of first lenses to pass through the plurality of regions, respectively. Furthermore, the light focused by the plurality of second lenses is allowed to pass through or shielded in the plurality of regions, respectively, depending on the state of the electric field of the corresponding electric field forming section. The first lens array converts the light focused by the second lenses and then passing through the light shielding member into output light as parallel light, using the first lenses.

[0007] In the optical device of [1], when an electric field is formed inside the electro-optical crystal by a certain electric field forming portion, a periodic change in the refractive index is instantaneously generated in the area inside the electro-optical crystal corresponding to the electric field forming portion. When the second parallel light passes through the electro-optical crystal in which the refractive index is periodically changed, 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 on a plurality of focal points separated from each other. In contrast, when the electric field is not formed inside the electro-optical crystal by a plurality of electric field forming portions, a periodic change in the refractive index is not generated inside the electro-optical crystal. Even if the second parallel light passes through such an electro-optical crystal, the phase distribution of the second parallel light does not change. Therefore, when the second parallel light is focused by the second lens, the light is focused on a single focal point.

[0008] Each area of the light-shielding component allows the light focused by the corresponding second lens to pass through or block it, depending on the state of the electric field of the corresponding electric field forming unit. In one example, each area of the light-shielding component blocks the light when the light is focused on multiple light-focusing points separated from each other, and allows the light to pass through when the light is focused on a single light-focusing point. In another example, each area of the light-shielding component allows the light to pass through when the light is focused on multiple light-focusing points separated from each other, and blocks the light when the light is focused on a single light-focusing point. Therefore, it is possible to freely determine whether multiple parts of the second parallel light corresponding to the multiple electric field forming units pass through the light-shielding component for each part. The light that passes through the light-shielding component in the light focused by the second lens array is converted by the first lens into output light as parallel light and output to the outside of the optical device. Therefore, by switching the electric field forming unit that forms the electric field, the configuration pattern of the parallel light in the plane perpendicular to the optical axis can be switched freely and at high speed.

[0009] [2] In the optical device of [1], the plurality of electric field forming portions may include: a first electrode provided on the main surface; and a second electrode provided on the back surface, configured to form an electric field within the electro-optical crystal together with the first electrode. The first electrode may be a transparent electrode configured to transmit the second parallel light. One or both of the first electrode and the second electrode may include a structure that is periodic in direction. In this case, it is possible to simply realize a structure that forms a periodic electric field within the electro-optical crystal and receives the second parallel light on the main surface of the electro-optical crystal.

[0010] [3] In the optical device of [2], one or both of the first electrode and the second electrode may be comb-shaped. In this case, the number of connection points between the first electrode and / or the second electrode having a periodic structure and the wiring for applying a voltage to the electrodes can be reduced. Therefore, the structure for applying a voltage to the electrodes can be simplified.

[0011] [4] In the optical device described in any one of [1] to [3], the plurality of regions of the light shielding member may be configured to allow light focused by the plurality of second lenses to pass through when the electric field of the corresponding electric field forming section among the plurality of electric field forming sections is in an off state, and to shield the light focused by the plurality of second lenses when the electric field of the electric field forming section is in an on state. When the electric field of the electric field forming section is in an on state, a periodic refractive index distribution is generated in the electro-optical crystal, and the phase distribution of the second parallel light changes. When output light is generated from the second parallel light, the phase distribution also remains in the output light. As a result, optical elements arranged in the subsequent stage of the optical device are affected by the phase distribution. On the other hand, when the electric field of the electric field forming section is in an off state, the refractive index distribution in the electro-optical crystal does not change, and the phase distribution of the second parallel light does not change. Therefore, by allowing the light focused by the second lens to pass through when the electric field of the electric field forming section is in an off state, the influence on the optical elements arranged in the subsequent stage of the optical device can be reduced.

[0012] [5] In the optical device of any one of [1] to [4], each of the plurality of first lenses and each of the plurality of second lenses may be a cylindrical lens having a refractive power primarily in the direction in which the intensity of the electric field periodically changes. Each of the plurality of regions may include a slit extending along the extension direction of the cylindrical lens. In this case, the focusing position of the cylindrical lens and the slit only need to be aligned in the direction in which the cylindrical lens primarily has a refractive power. Therefore, the manufacture of the optical device can be simplified.

[0013] [6] Another optical device of the present invention comprises a plate-shaped electro-optical crystal, a plurality of electric field forming parts, a first lens array, a light reflecting part and a light absorbing part. The electro-optical crystal has a main surface and a back surface, and is configured to receive first parallel light on the main surface and output the first parallel light from the back surface. The plurality of electric field forming parts are arranged in a one-dimensional or two-dimensional manner in a surface along the main surface or the back surface of the electro-optical crystal. The plurality of electric field forming parts respectively form an electric field whose intensity changes periodically in the direction along the main surface or the back surface in the electro-optical crystal, and are configured to be able to control the state of the electric field independently of each other. The first lens array has a plurality of first lenses corresponding to the plurality of electric field forming parts, and is configured to respectively focus the first parallel light output from the back surface of the electro-optical crystal through the plurality of first lenses. The light reflecting part has a plurality of regions corresponding to the plurality of electric field forming parts, and is configured to reflect or pass the light focused by the plurality of first lenses in the plurality of regions according to the state of the electric field of the corresponding electric field forming part in the plurality of electric field forming parts. The light absorbing part is configured to absorb the light that has passed through the light reflecting part. The first lens array converts the light reflected by the light reflecting portion into output light as parallel light through the first lens, and the electro-optical crystal transmits the output light.

[0014] In the optical device of [6], when an electric field is formed inside the electro-optical crystal by a certain electric field forming portion, a periodic change in the refractive index is instantaneously generated in the area inside the electro-optical crystal corresponding to the electric field forming portion. When the first parallel light passes through the electro-optical crystal in which the refractive index is periodically changed, 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 on a plurality of focal points separated from each other. When the electric field is not formed inside the electro-optical crystal by a plurality of electric field forming portions, a periodic change in the refractive index is not generated inside the electro-optical crystal. Even if the first parallel light passes through such an electro-optical crystal, the phase distribution of the first parallel light does not change. Therefore, when the first parallel light is focused by the first lens, the light is focused on a single focal point.

[0015] Each region of the light-reflecting portion reflects or passes the light focused by the corresponding first lens, depending on the state of the electric field of the corresponding electric field forming portion. In one example, each region of the light-reflecting portion allows the light to pass when the light is focused on multiple, mutually separated light-converging points, and reflects the light when the light is focused on a single light-converging point. In another example, each region of the light-reflecting portion reflects the light when the light is focused on multiple, mutually separated light-converging points, and allows the light to pass when the light is focused on a single light-converging point. Therefore, it is possible to freely determine, for each portion, whether the multiple portions of the first parallel light corresponding to the multiple electric field forming portions are reflected by the light-reflecting portion. The light reflected by the light-reflecting portion of the light focused by the first lens array is converted by the first lens into output light as parallel light and output to the outside of the optical device. The light that passes through the light-reflecting portion of the light focused by the first lens array is absorbed by the light-absorbing portion and disappears. Therefore, by switching the electric field forming portion that forms the electric field, the configuration pattern of the parallel light within a plane perpendicular to the optical axis can be switched freely and at high speed.

[0016] [7] In the optical device of [6], the plurality of electric field forming portions may include: a first electrode provided on the main surface; and a second electrode provided on the back surface, configured to form an electric field within the electro-optical crystal together with the first electrode. The first electrode and the second electrode may be transparent electrodes configured to allow the first parallel light to pass through. One or both of the first electrode and the second electrode may include a structure that is periodic in a direction. In this case, it is possible to simply realize a structure in which a periodic electric field is formed within the electro-optical crystal and the first parallel light and the output light pass through the electro-optical crystal.

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

[0018] [9] In the optical device of any one of [6] to [8], the plurality of regions of the light reflecting portion may be configured to reflect the light focused by the plurality of first lenses when the electric field of the corresponding electric field forming portion among the plurality of electric field forming portions is in an off state, and to pass the light focused by the plurality of first lenses when the electric field of the electric field forming portion is in an on state. When the electric field of the electric field forming portion is in an on state, a periodic refractive index distribution is generated in the electro-optical crystal, and the phase distribution of the first parallel light changes. When output light is generated from the first parallel light, the phase distribution also remains in the output light. In addition, when the output light passes through the electro-optical crystal, the phase distribution of the output light also changes. Therefore, the optical elements arranged in the subsequent stage of the optical device are affected by these phase distributions. When the electric field of the electric field forming portion is in an off state, the refractive index distribution in the electro-optical crystal does not change, and the phase distribution of the first parallel light and the output light does not change. Therefore, by reflecting the light focused by the first lens when the electric field of the electric field forming portion is in an off state, the influence on the optical elements arranged in the subsequent stage of the optical device can be reduced.

[0019]

[10] In the optical device of any one of [6] to [9], each of the plurality of first lenses may be a cylindrical lens having a refractive power mainly in the direction in which the intensity of the electric field periodically changes. The plurality of regions may also each include a light reflecting surface extending along the extension direction of the cylindrical lens. In this case, the focusing position of the cylindrical lens and the light reflecting surface only need to be aligned 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] The optical device according to any one of [1] to

[10] may further include a wiring substrate on which the electro-optical crystal is mounted. The wiring substrate may also include a plurality of terminals, each of which is electrically connected to a plurality of electric field forming units, and each of which supplies a driving voltage for forming an electric field to the plurality of electric field forming units. In this case, the driving voltage can be easily supplied to the plurality of electric field forming units via the wiring substrate.

[0021]

[12] In the optical device described in any one of [1] to

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

[0022]

[13] The optical device of the present invention may also include the optical device of any one of [1] to

[12] and a liquid crystal spatial light modulator. The spatial light modulator may also have a plurality of pixels, configured to receive output light from the optical device and modulate the phase of the output light for each pixel. The spatial light modulator may also have a plurality of modulation regions corresponding to the plurality of electric field forming portions of the optical device. According to this optical device, it is possible to increase the speed of switching the modulation pattern while sacrificing resolution.

[0023]

[14] The optical device of

[13] may further include a control unit for controlling the states of the electric fields of the plurality of electric field forming units and the modulation pattern of the spatial light modulator. The control unit may also control the plurality of electric field forming units so that the output light is incident on the plurality of modulation regions in sequence, and update the modulation pattern after the output light is incident on the plurality of modulation regions.

[0024]

[15] Another optical device of the present invention comprises the optical device of any one of [1] to

[12] , a light source, a polarizing plate, a polarization beam splitter, and a quarter wave plate. The light source is configured to output a first parallel light. The polarizing plate is configured to convert the first parallel light output from the light source into linearly polarized light. The polarization beam splitter is configured to guide the first parallel light, which will become linearly polarized light, to the optical device by transmitting or reflecting the first parallel light. The quarter wave plate is arranged on the optical path between the polarization beam splitter and the optical device. The polarization beam splitter reflects or transmits the output light output from the optical device and passing through the quarter wave plate. According to this optical device, it is possible to suppress a decrease in the light intensity of the output light, and to separate and extract the output light from the first parallel light. Effects of the Invention

[0025] According to the present invention, it is possible to provide an optical device capable of freely switching the arrangement pattern of parallel light in a plane perpendicular to the optical axis at high speed, and an optical apparatus capable of accelerating the switching of modulation patterns. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a cross-sectional view showing the structure of the optical device according to the first embodiment of the present invention. Figure 2 It is a perspective view showing an enlarged electro-optical crystal and a plurality of electric field forming portions. Figure 3 Schematic diagram showing the state inside the electro-optical crystal. Figure 4 Schematic diagram showing an example of switching of output light. Figure 5 It is a perspective view showing an example of a method of supplying voltage to the first electrode and the second electrode. Figure 6 It is a perspective view showing another example of the method of supplying voltage to the first electrode and the second electrode. Figure 7 It is a cross-sectional view showing the structure of an optical device according to a first modification. Figure 8 It is a cross-sectional view showing the structure of an optical device according to a second modification. Figure 9 It is a cross-sectional view showing the structure of an optical device according to a second embodiment. Figure 10 This is a diagram schematically showing the configuration of an optical device according to a third embodiment. Figure 11 It is a diagram schematically showing the structure of an optical device according to a fourth embodiment. Figure 12 This is a diagram showing the light modulation surface of a spatial light modulator. Figure 13 This is a flowchart showing the operation of the optical device. Figure 14 This is a timing chart showing an example of the operation of the optical device. Figure 15 It is a diagram schematically showing the structure of an optical device according to a fifth embodiment. Figure 16 Schematic diagram showing the state inside the electro-optical crystal. DETAILED DESCRIPTION

[0027] Hereinafter, embodiments of the optical device and optical apparatus of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and duplicate descriptions are omitted. (First embodiment)

[0028] Figure 1 1A is a cross-sectional view showing the structure of an optical device 1A according to a first embodiment of the present invention. Figure 1 As shown, an optical device 1A of this embodiment includes a plate-shaped electro-optical 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-optical crystal 10 includes, for example, at least one crystal selected from the group consisting of KTN crystal, potassium niobate, lithium niobate, potassium tantalate, lithium tantalate, potassium dihydrogen phosphate, dipotassium phosphate, and barium titanate. KTN crystal is a mixed crystal of potassium niobate and potassium tantalate, and exhibits an optical Kerr effect as an electro-optical effect. In one example, the electro-optical crystal 10 is composed of KTN crystal. The electro-optical 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-optical crystal 10 is consistent with the normal direction of the main surface 11 and the back surface 12.

[0030] The plurality of electric field forming parts 20 are arranged in a one-dimensional or two-dimensional manner along the main surface 11 and / or the back surface 12. Figure 1 , an example of three electric field forming sections 20 arranged in a row is shown, but the number of electric field forming sections 20 and the number of rows are not limited thereto. The plurality of electric field forming sections 20 form an electric field within the electro-optical crystal 10 whose intensity periodically varies in a direction D1 along the primary surface 11 and / or rear surface 12 of the electro-optical crystal 10. The plurality of electric field forming sections 20 are configured to be able to independently control the state of the electric field.

[0031] Figure 2(a) and (b) are enlarged perspective views showing the electro-optical crystal 10 and the plurality of electric field forming sections 20. Figure 2 (a) is a perspective view of the electro-optical crystal 10 as viewed from the main surface 11 side. Figure 2 (b) is a perspective view of the electro-optical crystal 10 as viewed from the back surface 12. Figure 2 As shown in (a), a first electrode 21 is provided on the entire surface of the main surface 11 of the electro-optical crystal 10. In the figure, the area where the first electrode 21 exists is represented by dots. Figure 2 As shown in (b), a plurality of (three in the example shown) second electrodes 22 are provided on the back surface 12 of the electro-optical crystal 10. In the figure, the area where the second electrode 22 is present is represented by dots. The first electrode 21 is a transparent electrode. The second electrode 22 can be a transparent electrode or an opaque electrode, such as a metal electrode. The constituent material of the transparent electrode is, for example, indium oxide with added tin such as tin oxide or tin oxide with added fluorine. The first electrode 21 and the second electrode 22 are formed on the surface of the electro-optical crystal 10, for example, by vacuum evaporation.

[0032] Each of the plurality of second electrodes 22 has a periodic structure in direction D1. A periodic structure, for example, is one in which regions where the second electrodes 22 are present and regions where they are absent alternate periodically. In one example, the second electrodes 22 have a comb shape with a plurality of comb teeth arranged in direction D1.

[0033] Each of the plurality of electric field forming portions 20 is formed by a second electrode 22 and a region of the first electrode 21 that faces the second electrode 22. The electro-optical crystal 10 exhibits the optical Kerr effect, a secondary electro-optical effect. When a voltage is applied between the second electrode 22 and the first electrode 21, an electric field corresponding to the magnitude of the voltage is formed in the portion of the electro-optical crystal 10 between them. Figure 3 (a) is a schematic diagram showing the state inside the electro-optical crystal 10 when no electric field is formed. Figure 3 (b) is a schematic diagram showing the state inside the electro-optical crystal 10 when an electric field is formed. Figure 3 As shown in (a), when no electric field is formed between the first electrode 21 and the second electrode 22, the refractive index distribution in the electro-optical crystal 10 is the same in the direction D1. Figure 3 As shown in (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 changes instantaneously relative to other regions within the electro-optical crystal 10. As a result, the refractive index of the region within the electro-optical crystal 10 corresponding to the electric field forming portion 20 changes periodically and instantaneously along the direction D1. This forms a diffraction grating with a binary refractive index distribution.

[0034] Refer again Figure 1. The first lens array 30 is a microlens array. The first lens array 30 is arranged opposite to the principal surface 11 of the electro-optical crystal 10. The first lens array 30 receives the first parallel light L1 having an optical axis along the normal direction of the principal surface 11 of the electro-optical crystal 10 on the opposite surface of the surface opposite to the electro-optical crystal 10. The first parallel light L1 is, for example, a laser output from a laser diode, an SLD (Super Luminescent Diode) or a solid laser. The wavelength of the first parallel light L1 is, for example, greater than 300 nm and less than 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 (3 in the example shown in the figure) first lenses 31 arranged in a one-dimensional or two-dimensional shape. The plurality of first lenses 31 correspond to the plurality of electric field forming portions 20, respectively. The first lens array 30 focuses the first parallel light L1 respectively through the plurality of first lenses 31. The plurality of first lenses 31 are, for example, convex lenses.

[0035] The second lens array 50 is a microlens array. The second lens array 50 is arranged between the electro-optical 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 (3 in the illustrated example) second lenses 51. The plurality of second lenses 51 respectively correspond to the plurality of first lenses 31 of the first lens array 30 and are optically coupled to 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 outputted from the plurality of first lenses 31 into the second parallel light L3 through the plurality of second lenses 51. The plurality of second lenses 51 are, for example, convex lenses.

[0036] The second parallel light L3 is incident on the main surface 11 of the electro-optical crystal 10 and passes through the electro-optical crystal 10 in the thickness direction of the electro-optical crystal 10. The electro-optical crystal 10 outputs the transmitted second parallel light L3 from the back surface 12. In order to maximize the transmittance of the second parallel light L3, the main surface 11 and the back surface 12 are polished. The light reflecting portion 13 is arranged on the back surface 12 side of the electro-optical crystal 10. The light reflecting portion 13 reflects the second parallel light L3 toward the main surface 11 of the electro-optical crystal 10. The light reflecting portion 13 is, for example, a dielectric multilayer film formed on the back surface 12 of the electro-optical crystal 10. In the case where the second electrode 22 is opaque, the second electrode 22 may also constitute a part of the light reflecting portion 13. The second lens array 50 focuses the second parallel light L3 reflected by the light reflecting portion 13 and output from the main surface 11 of the electro-optical crystal 10 through a plurality of second lenses 51.

[0037] When the second parallel light L3 is in the region of the electro-optical crystal 10 where the refractive index changes periodically (refer to Figure 3(b)) reciprocates along the thickness direction, 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 on a plurality of focal points P1 separated from each other in the direction of the periodic structure of the second electrode 22 (direction D1 in the example shown). Even if the second parallel light L3 is in the area of the electro-optical crystal 10 where the refractive index does not change periodically (refer to Figure 3 (a)) reciprocates along the thickness direction, and 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 on a single focal point P2. Figure 1 In the illustrated example, of the three electric field forming sections 20 arranged along the direction D1 , only the two electric field forming sections 20 located at both ends form an electric field, and the electric field forming section 20 located in the center does not form an electric field.

[0038] The light-shielding member 40 is arranged 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 corresponding to the plurality of electric field forming units 20. The plurality of regions 41 correspond to the plurality of second lenses 51, respectively, and are optically coupled to the plurality of second lenses 51 on one side thereof. The plurality of regions 41 correspond to the plurality of first lenses 31, respectively, and are optically coupled to the plurality of first lenses 31 on the other side thereof. The light-shielding member 40 is configured to allow the light L2 focused by the plurality of first lenses 31 to pass through the plurality of regions 41, respectively, and to allow the light L4 focused by the plurality of second lenses 51 to pass through or be shielded in the plurality of regions 41, respectively, according to the state of the electric field of the corresponding electric field forming unit 20.

[0039] In the illustrated example, each region 41 of the light-shielding member 40 blocks the light L4 when the light L4 is focused on a plurality of light-converging points P1 that are separated from each other, in other words, when the electric field of the corresponding electric field forming unit 20 is in the on state. In the illustrated example, each region 41 of the light-shielding member 40 allows the light L4 to pass through when the light L4 is focused on a single light-converging point P2, in other words, when the electric field of the corresponding electric field forming unit 20 is in the off state. Therefore, each region 41 of the light-shielding member 40 in the illustrated example has a single optical opening 42 corresponding to the single light-converging point P2. When the light L4 is focused on the single light-converging point P2, the light L4 passes through the optical opening 42. When the light L4 is focused on a plurality of light-converging points P1 that are separated from each other, the light L4 is shielded by the light-shielding member 40 outside the optical opening 42. The optical opening 42 may be an opening formed in the light-shielding member 40, or may be formed of a transparent material such as glass. Alternatively, the light shielding member 40 may be formed by providing a light shielding film on the surface of a transparent plate such as glass in a region other than the optical opening 42 .

[0040] In another example, each region 41 of the light shielding member 40 allows light L4 to pass when it is focused on multiple, separate focal points P1, and blocks light L4 when it is focused on a single focal point P2. In this case, each region 41 of the light shielding member 40 has an optical opening corresponding to the multiple focal points P1. The structure of the optical opening in this case can also be the same as the optical opening 42 described above.

[0041] The first lens array 30 converts the light L4 that has passed through the light shielding member 40 into output light L5 as parallel light 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 by the corresponding first lens 31 into output light L5 and output to the outside of the optical device 1A.

[0042] The spacing between the first lens array 30 and the shading member 40 , the spacing between the shading member 40 and the second lens array 50 , and the spacing between the second lens array 50 and the electro-optical 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 the present embodiment described above, whether or not each of the plurality of electric field forming sections 20 forms an electric field within the electro-optical crystal 10 is independently controlled for each electric field forming section 20. Thus, it is possible to freely determine, on a per-section basis, whether or not the plurality of portions of the second parallel light L3 corresponding to each of the plurality of electric field forming sections 20 pass through the light shielding member 40. Furthermore, by switching the electric fields formed by the electric field forming sections 20, it is possible to freely switch the arrangement pattern of the output light L5 within a plane perpendicular to the optical axis at high speeds, such as at the kHz level.

[0044] Figure 4 (a), (b) and (c) are schematic diagrams showing examples of switching of the output light L5. Figure 4 (a) indicates that light L4 only passes through Figure 1 The emission positions of the output light L5 when the light L4 is blocked in the region 41 located at the end of the three regions 41 and in the other two regions 41 . Figure 4 (b) indicates that light L4 only passes through Figure 1 The emission positions of the output light L5 when the light L4 is blocked in the center region 41 and the other two regions 41 among the three regions 41 shown. Figure 4 (c) indicates that light L4 is only Figure 1 The emission positions of the output light L5 when the central region 41 of the three regions 41 is shielded and the light L4 passes through the other two regions 41 are shown. The present invention is not limited to these examples, and the light L4 may pass through all of the multiple regions 41. Thus, according to 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] When the number of electric field forming units 20 is three as in the example shown in the figure, a total of seven configuration patterns can be realized: a configuration pattern of three types of output light L5 passing through only one region 41, a configuration pattern of three types of output light L5 passing through two regions 41, and a configuration pattern of one type of output light L5 passing through all regions 41. When the number of electric field forming units 20 is m, the number of configuration patterns that can be realized is expressed by the following formula (1). [Number 1]

[0046] As in this embodiment, the plurality of electric field forming portions 20 may each include a first electrode 21 provided on the principal surface 11 and a second electrode 22 provided on the rear surface 12. Furthermore, the second electrode 22 may also include a periodic structure. In this case, a structure for forming a periodic electric field within the electro-optical crystal 10 and receiving the second parallel light L3 on the principal surface 11 of the electro-optical crystal 10 can be easily realized.

[0047] As in this embodiment, the second electrode 22 may also be comb-shaped. In this case, the second electrode 22 including the periodic structure and the wiring for applying voltage to the second electrode 22 (eg Figure 5 The number of connection points of the terminal 62 shown in the figure can be reduced. Therefore, the structure for applying a voltage to the second electrode 22 can be simplified.

[0048] As in the present embodiment, the plurality of regions 41 of the light-shielding member 40 can also be configured so that the light L4 focused by the plurality of second lenses 51 passes through when the electric field of the corresponding electric field forming section 20 is in an off state, and is shielded when the electric field of the corresponding electric field forming section 20 is in an on state. When the electric field of the electric field forming section 20 is in an on state, a periodic refractive index distribution is generated in the electro-optical crystal 10, and the phase distribution of the second parallel light L3 changes. When the output light L5 is generated from the second parallel light L3, the phase distribution also remains in the output light L5, and the optical elements arranged in the subsequent stage of the optical device 1A are affected by the phase distribution. When the electric field of the electric field forming section 20 is in an off state, the refractive index distribution in the electro-optical crystal 10 does not change, and the phase distribution of the second parallel light L3 does not change. Therefore, the plurality of regions 41 of the light shielding member 40 are configured to allow the light L4 focused by the second lens 51 to pass therethrough when the electric field of the electric field forming unit 20 is in the off state, thereby reducing the influence on the optical elements arranged in the subsequent stage of the optical device 1A.

[0049] An acousto-optic deflector (AOD) is a device with the same function as the optical device 1A of this embodiment. However, the AOD's optical system becomes complex and the optical axis changes, requiring advanced adjustment technology. The optical device 1A of this embodiment only needs to be configured so that the principal surface 11 of the electro-optical crystal 10 is perpendicular to the optical axis of the first parallel light L1, and the optical axis does not change. Therefore, it is effective in combination with other devices, such as a spatial light modulator.

[0050] Here, Figure 5 2 is a perspective view showing an example of a method of supplying voltage to the first electrode 21 and the second electrode 22. Figure 5 As shown, the optical device 1A may further include a wiring substrate 60 on which the electro-optical crystal 10 is mounted. In the example shown in the figure, the wiring substrate 60 faces the back surface 12 of the electro-optical crystal 10. Figure 5 Illustration of the first lens array 30, the light shielding member 40, and the second lens array 50 is omitted.

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

[0052] The wiring substrate 60 is connected to another wiring substrate 67 via a wiring 66A with a connector. The wiring substrate 67 carries a plurality of switching elements 68 corresponding to the plurality of electric field forming units 20. The wiring substrate 67 is connected to the I / O connection terminal of the computer via a wiring 66B with a connector. A signal S1 for controlling the operation of the plurality of switching elements 68 is input from the computer. The wiring substrate 67 is connected to a DC power supply via a wiring 66C with a connector. The DC power supply supplies a DC power supply voltage V1 applied to the plurality of electric field forming units 20. Each switching element 68 is connected to a corresponding terminal 62 via a wiring 66A with a connector. Upon receiving the signal S1 from the computer, each switching element 68 supplies the DC power supply voltage V1 to the corresponding terminal 62. This DC power supply voltage V1 is applied to the second electrode 22 connected to the terminal 62.

[0053] exist Figure 5 In the example shown, the wiring substrate 60 carries a single electro-optical crystal 10, but the present invention is not limited to this example. Figure 6As shown, the wiring substrate 60 may also carry a plurality of electro-optical crystals 10. In this case, by arranging the plurality of electro-optical crystals 10 in a direction intersecting the arrangement direction (direction D1) of the plurality of electric field forming portions 20 in each electro-optical crystal 10, the plurality of electric field forming portions 20 can be arranged two-dimensionally.

[0054] As described above, the optical device 1A may further include a wiring substrate 60 on which the electro-optical crystal 10 is mounted. In this case, a driving voltage can be easily supplied to the plurality of electric field forming sections 20 via the wiring substrate 60 . (First Modification)

[0055] Figure 7 This is a cross-sectional view showing the structure of an optical device 1B according to a first variant of the above-described embodiment. In the optical device 1B, the plurality of first lenses 31 are cylindrical lenses having refractive power primarily in the direction in which the intensity of the electric field periodically varies. The direction in which the intensity of the electric field periodically varies is the direction of the periodic structure of the second electrode 22, which is direction D1 in the illustrated example. The plurality of second lenses 51 are also cylindrical lenses having refractive power in this direction. Therefore, the focal points P1 and P2 have a shape that extends linearly along the extension direction of the cylindrical lenses, in other words, along a 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 opening 42 of the light-shielding member 40 can also be a slit extending along the extension direction of the cylindrical lens. In this 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 unit 20 is X, the width of the optical opening 42 is, for example, (λF) / X. However, in practice, the width of the optical opening 42 may be different from (λF) / X due to the influence of the light intensity distribution and pattern of the first parallel light L1 and the like.

[0056] As in this variation, each of the multiple first lenses 31 and each of the multiple second lenses 51 can be a cylindrical lens having a refractive power primarily in the direction where the electric field intensity periodically varies. Each of the multiple regions 41 can also include a slit extending along the direction in which the cylindrical lens extends. In this case, alignment of the focusing position of the cylindrical lens and the slit only in the direction in which the cylindrical lens primarily has a refractive power is sufficient. This simplifies the manufacture of the optical device 1A. (Second Modification)

[0057] Figure 81 is a cross-sectional view showing the structure of an optical device 1C according to a second modified example of the above-described embodiment. The optical device 1C includes a plurality of electric field forming portions 23 instead of the plurality of electric field forming portions 20 of the above-described embodiment. The plurality of electric field forming portions 23 are arranged in a one-dimensional or two-dimensional manner within a surface along the main surface 11 and / or the back surface 12. The plurality of electric field forming portions 23 form an electric field within the electro-optical crystal 10 whose intensity periodically changes in a direction D1 along the main surface 11 and / or the back surface 12 of the electro-optical crystal 10. The plurality of electric field forming portions 23 are configured to be able to independently control the state of the electric field.

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

[0059] As in this modification, the first electrode provided on the principal surface 11 of the electro-optical crystal 10 may be divided into a plurality of parts to have a periodic structure. In this case, the same effects as those of the above embodiment can be achieved. (Second embodiment)

[0060] Figure 9 1D is a cross-sectional view showing the structure of an optical device 1D according to a second embodiment of the present invention. Figure 9 As shown, the optical device 1D of this embodiment includes an electro-optical crystal 10, a light absorbing portion 14, a plurality of electric field forming portions 20, a first lens array 30, and a light reflecting portion 90. Unlike the first embodiment, the electro-optical crystal 10 receives the first parallel light L1 on the main surface 11, and outputs the first parallel light L1 after passing through the electro-optical crystal 10 from the 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-optical crystal 10 and the plurality of electric field forming portions 20 are the same as those of the first embodiment or the second variant. Figure 9 , an example is shown in which the first electrode 21 has a periodic structure similarly to the second modification example, but the second electrode 22 may also have a periodic structure similarly to the first embodiment.

[0061] The first lens array 30 includes a plurality of first lenses 31 corresponding to the plurality of electric field forming sections 20. The first lens array 30 focuses the first parallel light L1 output from the back surface 12 of the electro-optical crystal 10 through the plurality of first lenses 31. Each of the plurality of first lenses 31 can be a cylindrical lens having refractive power primarily in the direction of the periodic structure of the first electrode 21 or the second electrode 22, in the illustrated example, in the direction D1.

[0062] When the first parallel light L1 passes through an area of the electro-optical crystal 10 where the refractive index undergoes periodic changes, 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 that passes through the first lens 31 is focused onto a plurality of mutually separated focal points P1 in the direction of the periodic structure of the first electrode 21, or in the illustrated example, direction D1. Even if the first parallel light L1 passes through an area of the electro-optical crystal 10 where the refractive index does not undergo periodic changes, the phase distribution of the first parallel light L1 does not change. Therefore, when the first parallel light L1 is focused by the first lens 31, the light L2 that passes through the first lens 31 is focused onto a single focal point P2. In the illustrated example, of the three electric field forming sections 20 arranged along direction D1, only the two electric field forming sections 20 at the ends form an electric field; the electric field forming section 20 in the center does not form an electric field. When the first lens 31 is a cylindrical lens, the focal points P1 and P2 have a shape that extends linearly along the extension direction of the cylindrical lens. In other words, the extending direction of the cylindrical lens is a direction intersecting both the direction of the periodic structure of the first electrode 21 and the optical axis direction of the first parallel light L1 .

[0063] The light reflecting portion 90 faces the back surface 12 of the electro-optical crystal 10 across the first lens array 30. The light reflecting portion 90 includes a plurality of regions 91 corresponding to the plurality of electric field forming portions 20. The plurality of regions 91 correspond to the plurality of first lenses 31 and are optically coupled to the plurality of first lenses 31. The light reflecting portion 90 is configured to reflect or pass light L2 focused by the plurality of first lenses 31 at the plurality of regions 91, 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 portion 90 allows light L2 to pass through when light L2 is focused on multiple, mutually separated light-converging points P1, in other words, when the electric field of the corresponding electric field forming portion 20 is in the on state. In the illustrated example, each region 91 of the light reflecting portion 90 reflects light L2 when light L2 is focused on a single light-converging point P2, in other words, when the electric field of the corresponding electric field forming portion 20 is in the off state. Therefore, each region 91 of the light reflecting portion 90 in the illustrated example has a single light-reflecting film 92 corresponding to the single light-converging point P2. When light L2 is focused on the single light-converging point P2, light L2 is reflected by the light-reflecting film 92. When light L2 is focused on multiple, mutually separated light-converging points P1, light L2 passes outside the light-reflecting film 92. The light-reflecting film 92 is, for example, a metal film or a dielectric film formed on the surface of a transparent plate 93 such as glass. When the first lens 31 is a cylindrical lens, the light-reflecting film 92 has a light-reflecting surface extending along the extension 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, the width of the light-reflecting film 92 in the direction D1 is, for example, (λF) / X. However, in practice, the width of the light-reflecting film 92 in the direction D1 may differ from (λF) / X due to the influence of the light intensity distribution and pattern of the first parallel light L1.

[0065] In another example, each region 91 of the light reflecting portion 90 reflects light L2 when it converges on multiple, separate focal points P1, and allows light L2 to pass through when it converges on a single focal point P2. In this case, each region 91 of the light reflecting portion 90 has a light reflecting film corresponding to the multiple focal points P1. The structure of the light reflecting film in this case can also be the same as that of the light reflecting film 92 described above.

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

[0067] The first lens array 30 converts the light L2 reflected by the light reflecting portion 90 into parallelized output light L5 at the first lens 31. Of the light L2 focused by the first lens array 30, the light L2 reflected by the light reflecting portion 90 is converted by the corresponding first lens 31 into output light L5 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 has passed through the light reflecting portion 90 is absorbed by the light absorbing portion 14 and disappears.

[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 length of the first lens array 30 and the second lens array 50 .

[0069] According to the optical device 1D of the present embodiment described above, whether each of the plurality of electric field forming sections 20 forms an electric field within the electro-optical crystal 10 can be independently controlled for each electric field forming section 20. Thus, whether or not the plurality of portions of the first parallel light L1 corresponding to each of the plurality of electric field forming sections 20 are reflected by the light reflecting section 90 can be freely determined for each portion. Furthermore, by switching the electric field formed by the electric field forming section 20, the arrangement pattern of the output light L5 within a plane perpendicular to the optical axis can be freely switched at high speeds, such as at the kHz level.

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

[0071] As in this embodiment, the first electrode 21 or the second electrode 22 may also be comb-shaped. In this case, the first electrode 21 or the second electrode 22 including the periodic structure and the wiring for applying voltage to the first electrode 21 or the second electrode 22, for example Figure 5 The number of connection points of the terminal 62 shown can be small. Therefore, the structure for applying a voltage to the first electrode 21 or the second electrode 22 can be simplified.

[0072] As in the present embodiment, the multiple regions 91 of the light reflecting portion 90 can also be configured to reflect the light L2 focused by the multiple first lenses 31 when the electric field of the corresponding electric field forming portion 20 is in the off state, and to allow the light L2 focused by the multiple first lenses 31 to pass through when the electric field of the corresponding electric field forming portion 20 is in the on state. When the electric field of the electric field forming portion 20 is in the on state, a periodic refractive index distribution is generated in the electro-optical crystal 10, and the phase distribution of the first parallel light L1 changes. When the output light L5 is generated from the first parallel light L1, its phase distribution also remains in the output light L5. In addition, when the output light L5 passes through the electro-optical crystal 10, the phase distribution of the output light L5 also changes. Therefore, the optical elements arranged in the subsequent stage of the optical device 1D are affected by these phase distributions. When the electric field of the electric field forming portion 20 is in the off state, the refractive index distribution in the electro-optical crystal 10 does not change, and the phase distributions of the first parallel light L1 and the output light L5 do not change. Therefore, the plurality of regions 91 of the light reflecting portion 90 are configured to reflect the light L2 focused by the first lens 31 when the electric field of the electric field forming portion 20 is in the off state, thereby reducing the influence on optical elements arranged in the subsequent stage of the optical device 1D.

[0073] The optical device 1D of this embodiment may further include Figure 5 or Figure 6 The wiring substrate 60 shown. In this case, the driving voltage can be easily supplied to the plurality of electric field forming portions 20 through the wiring substrate 60. The wiring substrate 60 used in this embodiment may also have an optical opening. The optical opening is formed at a position opposite to the electro-optical crystal 10, allowing the first parallel light L1 and the output light L5 to pass through. The optical opening may be an opening formed in the wiring substrate 60, or may be made of a transparent material such as glass. Alternatively, the wiring substrate 60 itself may be made of a transparent material such as glass. In this case, an optical opening is not required.

[0074] As described above, each of the multiple first lenses 31 can also be a cylindrical lens having a primary refractive power in the direction in which the electric field intensity periodically varies. Each of the multiple regions 91 can also include a light-reflecting surface extending along the extension direction of the cylindrical lens. In this case, alignment between the focusing position of the cylindrical lens and the light-reflecting surface is performed only in the direction in which the cylindrical lens primarily has a refractive power. This simplifies the manufacture of the optical device 1D. (Third embodiment)

[0075] Figure 10This diagram schematically illustrates the configuration of an optical device 70A according to a third embodiment of the present invention. The optical device 70A of this embodiment includes the optical device 1A of the first embodiment, a light source 71, a reflective mirror 72, an objective lens 73, a reflective mirror 74, a condenser lens 75, an imaging unit 76, a control unit 77, an I / O controller 78, a polarizing plate 84, a polarization beam splitter 85, and a quarter-wave plate 86. Instead of the optical device 1A of the first embodiment, the optical device 70A may 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.

[0076] The light source 71 outputs first parallel light L1. The light source 71 includes, for example, a laser diode, an SLD, or a solid-state laser. One surface of a polarizing plate 84 is optically coupled to the light source 71, thereby converting the first parallel light L1 output from the light source 71 into linearly polarized light. The polarizing beam splitter 85 is optically coupled to the other surface of the polarizing plate 84 and the optical device 1A, and transmits or reflects the linearly polarized first parallel light L1, thereby directing the first parallel light L1 toward the optical device 1A.

[0077] The quarter-wave plate 86 is positioned on the optical path between the polarization beam splitter 85 and the optical device 1A. The first parallel light L1, which has been linearly polarized, is converted to circularly polarized light 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 converted by the quarter-wave plate 86 into linearly polarized light having a polarization direction orthogonal to that of the first parallel light L1. The polarization beam splitter 85 separates the linearly polarized output light L5 from the first parallel light L1 by reflecting or transmitting the linearly polarized output light L5. This configuration suppresses any decrease in the light intensity of the output light L5 while separating and extracting the output light L5 from the first parallel light L1.

[0078] The reflector 72 is, for example, a half-mirror or a dielectric reflector. The reflector 72 transmits the output light L5 extracted by the polarization beam splitter 85. The objective lens 73 focuses the output light L5 that has passed through the reflector 72 toward the irradiation target surface B1 of the object B. The irradiation target surface B1 receives the light L6 focused by the objective lens 73, generating light L7. For example, light L7 is scattered light from the irradiation target surface B1. Alternatively, when the output light L5 and light L6 are excitation light, light L7 is fluorescence output from the excited object B. The light L7 is formed into parallel light L8 by the objective lens 73. The parallel light L8 is separated from the output light L5 by being reflected by the reflector 72. After being reflected by the reflector 74, the parallel light L8 is focused by the focusing lens 75 toward the imaging unit 76. 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 light beams L5 are focused and irradiated onto the target illumination surface B1. In this case, interference fringes are formed on surfaces other than the target illumination surface B1, due to the mutual interference of the two light beams L6. These interference fringes can be used as structured illumination. Alternatively, three output light beams L5 that are not aligned can be focused and irradiated onto the target illumination surface B1. In this case, the three light beams L6 interfere with each other, forming a grid-like pattern of light spots. This grid-like pattern 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 driving voltage to the plurality of electric field forming units 20 of the optical device 1A. The I / O controller 78 is electrically connected to the control unit 77 and is controlled by the control unit 77. The I / O controller 78 includes, for example, Figure 5 The wiring substrate 67 and the plurality of switch elements 68 are shown. The control unit 77, for example, Figure 5 Signal S1 is provided to I / O controller 78. Control unit 77 is a personal computer, a smart device such as a smartphone or tablet terminal, or a computer such as a cloud server. The computer serving as control unit 77 includes a storage device such as an HDD (Hard Disk Drive), flash memory, or RAM (Random Access Memory), and a processor (CPU: Central Processing Unit). Control unit 77 may also be composed of a microcomputer or an FPGA (Field-Programmable Gate Array).

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

[0082] Figure 11This figure schematically illustrates the structure of an optical device 70B according to a fourth embodiment of the present invention. The optical device 70B of this embodiment includes the optical device 1A of the first embodiment, a light source 71, a reflector 72, an objective lens 73, reflectors 74a, 74b, and 74c, a condenser 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. The optical device 70B 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. The first parallel light L1 output from the light source 71 is coherent laser light whose phase is spatially aligned. The structure 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] The reflectors 74a and 74b reflect the output light L5 extracted by the polarization beam splitter 85 and guide the output light L5 to the SLM81. The SLM81 is a liquid crystal type SLM. The SLM81 has a plurality of pixels, receives the output light L5, and modulates the phase of the output light L5 for each pixel. The SLM81 can be a reflective type or a transmissive type. The reflector 72 is, for example, a half mirror or a dielectric mirror. The reflector 72 transmits the modulated output light L5 output from the SLM81. The objective lens 73 focuses the output light L5 transmitted by the reflector 72 toward the irradiation target surface B1 of the object B. The irradiation target surface B1 receives the light L6 focused by the objective lens 73 and generates light L7. For example, the light L7 is scattered light from the irradiation target surface B1. Alternatively, when the output light L5 and the light L6 are excitation light, the light L7 is fluorescence output from the excited object B. The light L7 is formed into parallel light L8 by the objective lens 73. The parallel light L8 is reflected by the reflective mirror 74c and then focused by the condensing lens 75 toward the imaging unit 76. 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 a signal indicating a modulation pattern to the SLM 81. The SLM controller 80 is electrically connected to the optical device 1A and applies a drive voltage to the plurality of electric field forming units 20 of the optical device 1A. Furthermore, the SLM controller 80 is electrically connected to the imaging unit 76 and provides a trigger signal indicating imaging timing to the imaging unit 76. The SLM controller 80 is electrically connected to the control unit 79 and is controlled by the control unit 79. The SLM controller 80 has, for example, Figure 5 The wiring substrate 67 and the plurality of switching elements 68 are shown. The control unit 79 controls the state of the electric field of the plurality of electric field forming units 20 and the modulation pattern of the SLM 81. The control unit 79 controls, for example, Figure 5The signal S1 shown is supplied to the SLM controller 80. The control unit 79 is a personal computer, a smart device such as a smartphone or tablet terminal, or a computer such as a cloud server. The computer serving as the control unit 79 includes a storage device such as an HDD, flash memory, or RAM, and a processor (CPU). The control unit 79 may also be configured as a microcomputer or an FPGA (Field-Programmable Gate Array).

[0085] The SLM81 has a plurality of modulation areas corresponding to the plurality of electric field forming parts 20 of the optical device 1A. Moreover, a separate modulation pattern is presented in each modulation area. The modulation pattern can be, for example, a double-beam interference pattern required for structured lighting or a multi-beam interference pattern representing a grating pattern. In this case, a plurality of (for example, 5×5 or 1×5) light spots distributed in a two-dimensional manner are formed on the irradiated object surface B1. The configuration and number of the light spots formed can also be different for each modulation area. In this way, by presenting a separate modulation pattern in each modulation area, the irradiation pattern of the irradiated object surface B1 changes according to the switching of the configuration pattern of the output light L5.

[0086] Here, for the sake of explanation, an embodiment is assumed in which the optical device 1A includes the electric field forming sections 20 in three rows and three columns (nine in total). Figure 12 : is a diagram showing the light modulation surface of SLM81 at this time. Figure 12 As shown, the SLM81 has 9 modulation areas M(1) to M(9), the same number as the electric field forming section 20. The modulation areas M(1) to M(9) are arranged in 3 rows and 3 columns in the same manner as the electric field forming section 20. The modulation areas M(1) to M(9) correspond one-to-one to the 9 electric field forming sections 20. The output light L5 output from the optical device 1A through the corresponding electric field forming section 20 is incident on the 9 modulation areas M(1) to M(9) and modulated. The control section 79 controls the applied voltage applied to the 9 electric field forming sections 20, and the output light L5 is incident on the modulation areas M(1) to M(9) in sequence and modulated. Then, after the output light L5 is incident on the modulation areas M(1) to M(9), the control section 79 updates the modulation pattern of the SLM81 through the SLM controller 80. After that, the control unit 79 controls the voltages applied to the nine electric field forming units 20 again, and the output light L5 is incident on the modulation regions M(1) to M(9) in sequence and modulated. The optical device 70B repeats this operation.

[0087] Figure 13 70B is a flowchart showing the operation of the optical device 70B. Figure 13As shown, first, the control unit 79 sets the modulation pattern of the SLM 81 through the SLM controller 80 (step ST1). The modulation pattern includes individual modulation patterns for each of the plurality of modulation regions M(1) to M(9). Next, the control unit 79 controls the nine electric field forming units 20 through the SLM controller 80, so that the output light L5 is incident on the modulation region M(1) (step ST2). Then, the control unit 79 provides a trigger signal indicating the imaging timing to the imaging unit through the SLM controller 80. As a result, the imaging unit 76 performs imaging (step ST3). After that, the control unit 79 returns to step ST2, and the output light L5 is incident on the modulation region M(2), and step ST3 is performed again. In this way, the output light L5 is sequentially incident on all the modulation regions M(1) to M(9), and step ST3 is performed each time. After the output light L5 is incident on all the modulation regions M(1) to M(9) (step ST4: yes), the control unit 79 returns to step ST1 and updates the modulation pattern of the SLM 81. The modulation pattern includes individual modulation patterns for each of the plurality of modulation regions M(1) to M(9). Steps ST2 to ST4 are then repeated. After all the modulation patterns prepared in advance are presented (step ST5: Yes), the optical device 70B ends its operation.

[0088] The effects obtained by the optical device 70B of this embodiment are as follows. In the liquid crystal type SLM81, an electric field is formed separately inside the liquid crystal layer by a plurality of electrodes. However, since the response of the liquid crystal is delayed relative to the time change of the electric field inside the liquid crystal layer, there is a problem that the high speed of switching the modulation pattern is impaired. In this embodiment, the light modulation surface of the SLM81 is divided into a plurality of modulation areas M(1) to M(9), and the optical device 1A is used to sequentially input the output light L5 to each of the plurality of modulation areas M(1) to M(9). Thus, the switching of the modulation pattern can be accelerated at the expense of resolution. The optical device 70B can perform holographic light control at a high rate and can be applied to the observation of high-speed phenomena, or optical tweezers technology or atom trapping technology that requires a high frame rate.

[0089] In the above description, the modulation pattern of SLM81 is updated after the output light L5 is incident on all modulation areas M(1) to M(9). However, this example is not limiting, and the modulation pattern of SLM81 may be divided into two or more areas (e.g., three areas), and the modulation pattern may be updated for each area. Figure 14 is a timing diagram showing an example of such an operation. Figure 14In the figure, line G1 represents the period during which the output light L5 is incident on the modulation areas M(1) to M(9). In the interval where line G1 is at a high level, the output light L5 is incident on any modulation area. The number marked near line G1 represents the number i of the modulation area M(i) on which the output light L5 is incident. Line G2 represents the period during which the modulation pattern of the modulation areas M(1) to M(3) is presented. In the interval T1 where line G2 is at a high level, the modulation pattern of the modulation areas M(1) to M(3) is presented. Line G3 represents the period during which the modulation pattern of the modulation areas M(4) to M(6) is presented. In the interval T2 where line G3 is at a high level, the modulation pattern of the modulation areas M(4) to M(6) is presented. Line G4 represents the period during which the modulation pattern of the modulation areas M(7) to M(9) is presented. In the interval T3 where line G4 is at a high level, the modulation pattern of the modulation areas M(7) to M(9) is presented.

[0090] Due to the response delay of the liquid crystal layer, for example, when the modulation pattern of the modulation areas M(1) to M(3) is presented in interval T1, the voltage application to the electrodes of the modulation areas M(1) to M(3) begins at timing t1 before interval T1. Furthermore, after the voltage application to the electrodes ends at the end of interval T1, the presentation of the modulation pattern completely ends at timing t2 after interval T1. The same applies to the case where the modulation pattern of the modulation areas M(4) to M(6) is presented in interval T2, and the case where the modulation pattern of the modulation areas M(7) to M(9) is presented in interval T3.

[0091] In this way, the modulation pattern of SLM81 is divided into two or more areas, and the modulation pattern is updated for each area. Figure 14 As shown in the timing chart of , the output light L5 can be repeatedly incident on the modulation regions M(1) to M(9) without being affected by the response time of the liquid crystal layer. Therefore, the switching of the modulation pattern can be further accelerated. (Fifth embodiment)

[0092] Figure 15 This diagram schematically illustrates the configuration of an optical device 70C according to a fifth embodiment of the present invention. In addition to the configuration of the optical device 70B according to the fourth embodiment, the optical device 70C further includes an SLM controller 82 and an SLM 83. The imaging unit 76 of this embodiment employs a rolling shutter method that sequentially detects light from a plurality of light incident areas arranged in one direction.

[0093] The SLM controller 82 is electrically connected to the SLM 83 and provides a signal representing a modulation pattern to the SLM 83. The SLM controller 82 is electrically connected to the control unit 79 and is controlled by the control unit 79. The control unit 79 controls the modulation pattern presented by the SLM 83 through the SLM controller 82. The modulation pattern presented by the SLM 83 causes the focusing lens 75 to form a focused image of the light L9 at multiple positions. The focused images of the light L9 at multiple positions are identical. Because the imaging unit 76 has a rolling shutter method, the imaging unit 76 sequentially captures the multiple focused images of the light L9 formed at multiple positions with equal time intervals. As a result, the focused image of the light L9 can be captured at a rate faster than the original frame rate of the imaging unit 76.

[0094] The optical device and optical apparatus of the present invention are not limited to the above-described embodiments and are capable of various other variations. For example, in the first embodiment described above, the second electrode 22 includes a periodic structure in the direction D1, and the first electrode 21 is formed entirely on the back surface 12. In the second variation described above, the first electrode 21 includes a periodic structure in the direction D1, and the second electrode 22 is formed entirely on the back surface 12. Without being limited to these embodiments, both the first electrode 21 and the second electrode 22 may include a periodic structure in the direction D1. In this case, both the first electrode 21 and the second electrode 22 may have a comb shape. Figure 16 Schematic diagrams showing the state of the electro-optical crystal 10 in such a manner: (a) when no electric field is formed and (b) when an electric field is formed. Figure 16 As shown in (b), in such a manner, if 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 changes instantaneously relative to other regions within the electro-optical crystal 10. As a result, in the region inside the electro-optical crystal 10 corresponding to the electric field forming portion 20, the refractive index changes periodically and instantaneously along the direction D1. In this way, in the case where both the first electrode 21 and the second electrode 22 include a periodic structure in the direction D1, the expansion of the electric field in the direction D1 can be suppressed compared to the case where the first electrode 21 or the second electrode 22 is formed on the entire main surface 11 or the back surface 12. Therefore, a periodic refractive index distribution can be formed in a more orderly shape.

[0095] In the first embodiment, the directions of the periods in the periodic structures of the plurality of second electrodes 22 are consistent among the plurality of second electrodes 22. Without limitation to this embodiment, the directions of the periods in the periodic structures of at least one second electrode 22 may be different from the directions of the periods in the periodic structures of the other second electrodes 22. Similarly, in the second modified example, the directions of the periods in the periodic structures of the plurality of first electrodes 21 are consistent among the plurality of first electrodes 21. Without limitation to this embodiment, the directions of the periods in the periodic structures of at least one first electrode 21 may be different from the directions of the periods in the periodic structures of the other first electrodes 21.

[0096] 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 portion that forms an electric field whose intensity varies periodically in the electro-optical crystal 10 is not limited to this form. For example, the electric field forming portion may also have a plurality of electrodes arranged in a two-dimensional shape. In this case, a voltage may be selectively applied to a part of the plurality of electrodes to form an electric field whose intensity varies periodically. Alternatively, one of the first electrode 21 and the second electrode 22 may be in a comb shape, or in another form that can form an electric field whose intensity varies periodically in the electro-optical crystal 10, and the other electrode may be in a form having a plurality of electrodes arranged in a two-dimensional shape. In this case, the other electrode may also be used to form an electric field for correcting the refractive index distribution caused by the deviation of the electro-optical effect in the electro-optical crystal 10 to a desired distribution, such as a uniform distribution.

[0097] The electrodes described as being transparent electrodes in the above embodiments may be non-transparent electrodes, such as metal electrodes. In this case, the electrodes may have a structure for allowing light to pass, such as an opening. Description of Reference Signs

[0098] 1A to 1D…Optical device, 10…Electro-optical crystal, 11…Main surface, 12…Back surface, 13…Light reflecting portion, 14…Light absorbing portion, 20…Electric field forming portion, 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 substrate, 62, 63…Terminal, 64…Conductive paste, 65…Bonding wire, 66A, 66B, 66C…Wiring with connector, 67…Wiring substrate, 68…Switching element, 70A, 70B, 70C…Optical device, 71…Light source, 72…Reflecting mirror, 73…Objective lens, 74, 74a , 74b, 74c…reflecting mirror, 75…condensing lens, 76…shooting unit, 77, 79…control unit, 78…I / O controller, 80, 82…SLM controller, 81, 83…spatial light modulator (SLM), 84…polarizer, 85…polarization beam splitter, 86…quarter wave plate, 90…light reflecting unit, 91…area, A1…area, B…object, B1…irradiation object 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) to M(9), M(i)…modulation area, P1, P2…focusing point, S1…signal, V1…DC power supply voltage.

Claims

1. An optical device, wherein: have: a first lens array having a plurality of first lenses arranged in a one-dimensional or two-dimensional manner, and configured to focus the first parallel light through the plurality of first lenses; a second lens array having a plurality of second lenses corresponding to the plurality of first lenses, and configured to convert the light outputted from the plurality of first lenses into second parallel light through the plurality of second lenses; a plate-shaped electro-optical crystal having a main surface and a back surface, and configured to receive the second parallel light on the main surface; a light reflecting portion disposed on the back surface side of the electro-optical crystal and configured to reflect the second parallel light toward the main surface; a plurality of electric field forming sections, each disposed corresponding to the plurality of second lenses, forming an electric field whose intensity periodically varies in a direction along the principal surface or the rear surface within the electro-optical crystal, and configured to be able to control the state of the electric field independently of one another; and a light shielding member disposed between the first lens array and the second lens array, The second lens array collects the second parallel light reflected by the light reflecting portion and output from the main surface of the electro-optical crystal through the plurality of second lenses. The light shielding member has a plurality of regions corresponding to the plurality of electric field forming sections, and is configured to allow the light focused by the plurality of first lenses to pass through the plurality of regions, respectively, and to allow or shield the light focused by the plurality of second lenses in the plurality of regions, respectively, according to the state of the electric field of the corresponding electric field forming section among the plurality of electric field forming sections. The first lens array converts the light focused by the second lens and then passing through the light shielding member into output light as parallel light through the first lens.

2. The optical device according to claim 1, wherein The plurality of electric field forming parts respectively include: a first electrode disposed on the main surface; and a second electrode disposed on the back surface and configured to form the electric field in the electro-optical crystal together with the first electrode; The first electrode is a transparent electrode configured to transmit the second parallel light. One or both of the first electrode and the second electrode include a structure that is periodic in the 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 any one of claims 1 to 3, wherein: The multiple areas of the light-shielding component are respectively constructed to allow the light respectively focused by the multiple second lenses to pass through when the electric field of the corresponding electric field forming part among the multiple electric field forming parts is in an off state, and to shield the light respectively focused by the multiple second lenses when the electric field of the electric field forming part is in an on state.

5. The optical device according to any one of claims 1 to 4, wherein: Each of the plurality of first lenses and each of the plurality of second lenses is a cylindrical lens having refractive power mainly in the direction, The plurality of regions respectively include a slit extending along an extending direction of the cylindrical lens.

6. An optical device, wherein: have: A plate-shaped electro-optical crystal having a main surface and a back surface, configured to receive first parallel light on the main surface and output the first parallel light from the back surface; a plurality of electric field forming portions arranged in a one-dimensional or two-dimensional manner along the main surface or the back surface of the electro-optical crystal, each forming an electric field in the electro-optical crystal whose intensity periodically changes in a direction along the main surface or the back surface, and configured to be able to control the state of the electric field independently of each other; a first lens array having a plurality of first lenses corresponding to the plurality of electric field forming portions, and configured to respectively focus the first parallel light output from the back surface of the electro-optical crystal through the plurality of first lenses; a light reflecting portion having a plurality of regions corresponding to the plurality of electric field forming portions, the light reflected by the plurality of first lenses being reflected or passing through the plurality of regions, respectively, according to a state of the electric field of a corresponding electric field forming portion among the plurality of electric field forming portions; and a light absorbing portion configured to absorb the light having passed through the light reflecting portion, The first lens array converts the light reflected by the light reflecting portion into output light as parallel light through the first lens, and the electro-optical crystal transmits the output light.

7. The optical device according to claim 6, wherein: The plurality of electric field forming parts respectively include: a first electrode disposed on the main surface; and a second electrode disposed on the back surface and configured to form the electric field in the electro-optical crystal together with the first electrode; The first electrode and the second electrode are transparent electrodes configured to transmit the first parallel light. One or both of the first electrode and the second electrode include a structure that is periodic in the 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 any one of claims 6 to 8, wherein: The multiple areas of the light reflecting portion are respectively constructed to reflect the light respectively focused by the multiple first lenses when the electric field of the corresponding electric field forming portion among the multiple electric field forming portions is in an off state, and to allow the light respectively focused by the multiple first lenses to pass through when the electric field of the electric field forming portion is in an on state.

10. The optical device according to any one of claims 6 to 9, wherein: The plurality of first lenses are cylindrical lenses having refractive power mainly in the direction, Each of the plurality of regions includes a light reflecting surface extending along an extending direction of the cylindrical lens.

11. The optical device according to any one of claims 1 to 10, wherein: It also includes a wiring substrate carrying the electro-optical crystal, The wiring substrate includes a plurality of terminals, each of which is electrically connected to the plurality of electric field forming units and supplies a drive voltage for forming the electric field to each of the plurality of electric field forming units.

12. The optical device according to any one of claims 1 to 11, wherein: The electro-optical crystal includes a KTN crystal.

13. An optical device, wherein: have: The optical device according to any one of claims 1 to 12; and A liquid crystal spatial light modulator having a plurality of pixels, configured to receive the output light from the optical device and modulate the phase of the output light for each pixel. The spatial light modulator has a plurality of modulation regions corresponding to the plurality of electric field forming parts of the optical device, respectively.

14. The optical device according to claim 13, wherein further comprising: a control unit configured to control the states of the electric fields of the plurality of electric field forming units and the modulation pattern of the spatial light modulator, The control section controls the plurality of electric field forming sections so that the output light is incident on the plurality of modulation regions in sequence, and updates the modulation pattern after the output light is incident on the plurality of modulation regions.

15. An optical device, wherein: have: The optical device according to any one of claims 1 to 12; a light source configured to output the first parallel light; a polarizing plate configured to convert the first parallel light output from the light source into linearly polarized light; a polarization beam splitter configured to guide the first parallel light, which has become linearly polarized light, to the optical device by transmitting or reflecting the first parallel light; and A quarter wave plate is arranged on the optical path between the polarization beam splitter and the optical device. The polarization beam splitter reflects or transmits the output light output from the optical device and passing through the 1 / 4 wave plate.

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