Spatial light modulation element, optical unit, and light processing device

Abstract

A spatial light modulation element (100) is provided with: an optical member (110) which is formed using a ferroelectric material having light transmissivity, and on which processing light traveling along a Z direction is incident as incident light; positive and negative electrodes (120, 125) that are disposed on a disposition surface (113) of the optical member (110) along an X direction; and wiring (positive lines (130) and ground lines (135)) that applies voltage to the positive electrodes (120) such that a potential difference is generated between the positive and negative electrodes (120, 125). When the potential difference has been generated between the positive and negative electrodes (120, 125), the refractive index in the optical member (110) changes along the X direction.

Description

Spatial light modulation element, optical unit, and optical processing device

[0001] The present invention relates to a spatial light modulation element, an optical unit, and an optical processing device.

[0002] Known electro-optic spatial light modulation elements include a spatial light modulation element in which an electrode is provided on one side of an optical member that propagates light (see, for example, Patent Document 1), and a spatial light modulation element in which electrodes are provided on both sides of an optical member that propagates light. Such spatial light modulation elements are required to modulate light at high speed.

[0003] U.S. Patent No. 6,169,565

[0004] A first spatial light modulation element according to the present invention is a spatial light modulation element that modulates and emits incident light, and includes an optical element on which the incident light traveling along a first axis is incident and which is formed using a translucent ferroelectric material, first and second electrodes that are arranged on the surface of the optical element along a second axis that intersects with the first axis, and wiring that applies a voltage to at least one of the first and second electrodes so as to create a potential difference between the first and second electrodes.

[0005] A second spatial light modulation element according to the present invention is a spatial light modulation element that modulates and emits incident light, and includes an optical element that receives the incident light traveling along a first axis and is formed using a translucent ferroelectric material, and first and second electrodes that are arranged on the surface of the optical element along a second axis that intersects with the first axis, and when a potential difference is generated between the first and second electrodes, the refractive index within the optical element changes along the second axis.

[0006] The optical unit according to the present invention comprises the above-mentioned spatial light modulation element and an optical system into which diffracted light emitted from the spatial light modulation element is incident, and the optical system has a dimming section that dims at least one of the zeroth-order diffracted light in the diffracted light and diffracted light of an order different from the zeroth-order diffracted light.

[0007] The optical processing device according to the present invention is an optical processing device that processes an object using processing light from a light source, and includes the above-mentioned optical unit and an irradiation device that irradiates the object with the processing light from the light source via the optical unit.

[0008] 1 is a schematic configuration diagram showing an optical processing device; FIG. 2 is a cross-sectional view showing a part of the optical processing device; FIG. 3 is a schematic view of a spatial light modulation element unit as viewed from the incident surface side; FIG. 4 is a front view of a lens array; FIG. 5 is a schematic configuration diagram showing a first modified example of the optical processing device; FIG. 6 is a schematic configuration diagram showing a second modified example of the optical processing device; FIG. 7 is a plan view of a spatial light modulation element according to the first embodiment; FIG. 8 is a plan view showing a state in which processing light is incident on the spatial light modulation element according to the first embodiment; FIG. 9 is a side view of the spatial light modulation element according to the first embodiment; FIG. 10 is a cross-sectional view of the spatial light modulation element according to the first embodiment; FIG. 11 is a plan view of a conventional spatial light modulation element; FIG. 12 is a side view of a conventional spatial light modulation element; FIG. 13 is a cross-sectional view of a conventional spatial light modulation element; FIG. 14 is a cross-sectional view of a conventional spatial light modulation element; FIG. 15 is a cross-sectional view showing a case in which the distance between electrodes is narrowed in a conventional spatial light modulation element; FIG. 16 is a cross-sectional view showing a case in which the distance between electrodes is widened in a conventional spatial light modulation element; FIG. 17 is a side view of a first modified example of the spatial light modulation element according to the first embodiment; FIG. 18 is a side view of a second modified example of the spatial light modulation element according to the first embodiment; FIG. 19 is a plan view of a spatial light modulation element according to the second embodiment; FIG. 19 is a plan view showing a state in which processing light is incident on the spatial light modulation element according to the second embodiment. FIG. 1 is a side view of a spatial light modulation element according to a second embodiment. FIG. 2 is a cross-sectional view of the spatial light modulation element according to the second embodiment. FIG. 3 is a plan view of a spatial light modulation element according to a third embodiment. FIG. 4 is a side view of a spatial light modulation element according to the third embodiment. FIG. 5 is a plan view showing a modified example of the spatial light modulation element according to the third embodiment. FIG. 6 is a plan view of a spatial light modulation element according to a fourth embodiment. FIG. 7 is a side view of a spatial light modulation element according to the fourth embodiment. FIG. 8 is a plan view showing a modified example of the spatial light modulation element according to the fourth embodiment. FIG. 9 is a plan view of a spatial light modulation element according to a fifth embodiment. FIG. 10 is a plan view of a spatial light modulation element according to a sixth embodiment.

[0009] Preferred embodiments will be described below. First, an optical unit and an optical processing device equipped with a spatial light modulation element according to each embodiment will be described with reference to Figures 1 to 4. In the description of the optical processing device, the directions indicated by the arrows in Figure 1 may be referred to as the X direction, Y direction, and Z direction, respectively. The X direction, Y direction, and Z direction are directions that are perpendicular to one another.

[0010] 1, the optical processing device 1 includes a light source 5, a processing optical system 10, an irradiation device 30, and a control device 40. The optical processing device 1 performs removal processing on the workpiece W1 by irradiating the workpiece W1 placed at a predetermined position (for example, the upper surface of the stage ST) with processing light EL.

[0011] The light source 5 emits processing light EL, such as laser light. The light source 5 may be a laser light source that emits pulsed light as the processing light EL. In this case, the pulsed light may be pulsed light also known as femtosecond laser. The processing light EL may be a type of light different from laser light, as long as it can process the workpiece W1 when irradiated onto the workpiece W1. The wavelength range of the processing light EL may be any wavelength range, as long as it can process the workpiece W1 when irradiated onto the workpiece W1. For example, the wavelength range of the processing light EL may be the wavelength range of visible light, the wavelength range of infrared light, or the wavelength range of ultraviolet light.

[0012] Processing light EL emitted from the light source 5 is incident on the processing optical system 10. The processing optical system 10 splits the processing light EL incident on the processing optical system 10 into multiple processing lights (for example, nine processing lights arranged in threes vertically and threes horizontally) and emits them toward the irradiation device 30. The multiple processing lights EL emitted from the processing optical system 10 are irradiated onto the workpiece W1 via the galvanometer mirror 31 and scanning optical system 35 of the irradiation device 30. The direction along the optical axis of the processing optical system 10 is defined as the Z direction. The horizontal direction perpendicular to the Z direction may be defined as the X direction, and the direction perpendicular to the Z direction and the X direction may be defined as the Y direction.

[0013] The machining optical system 10 includes, arranged in order from the light source 5 side, a diffractive optical element 11, a collector lens 12, a collimator lens 13, an optical isolator 14, a cylindrical expander 15, a cylindrical lens 16, an optical unit 20 having a spatial light modulation function, and a condenser lens 29. The machining light EL emitted from the light source 5 is incident on the diffractive optical element 11. The diffractive optical element 11 splits the machining light EL incident on the diffractive optical element 11 into multiple machining light beams through diffraction. In the example shown in FIG. 1 , the diffractive optical element 11 splits the machining light EL incident on the diffractive optical element 11 into a machining light EL that travels along the optical axis of the machining optical system 10 and two machining light beams that travel at an angle in the ±Y direction with respect to the optical axis of the machining optical system 10.

[0014] 1, the diffractive optical element 11 splits the processing light EL incident on the diffractive optical element 11 into three processing light beams, but this is not limited thereto. The diffractive optical element 11 may split the processing light EL incident on the diffractive optical element 11 into five processing light beams, and it is only necessary that the diffractive optical element 11 splits the processing light EL incident on the diffractive optical element 11 into two or more processing light beams.

[0015] The plurality of processing light beams EL emitted from the diffractive optical element 11 are incident on the collector lens 12. The front focal position of the collector lens 12 may be located on the grating plane of the diffractive optical element 11. The collector lens 12 makes the traveling directions of the plurality of processing light beams EL passing through the collector lens 12 parallel to each other. The collector lens 12 also focuses each of the processing light beams EL passing through the collector lens 12.

[0016] A plurality of collimator lenses 13 are arranged side by side in the Y direction in alignment with the plurality of processing light beams EL. When the diffractive optical element 11 splits the processing light beam EL into three beams as shown in Fig. 1, three collimator lenses 13 may be arranged side by side in the Y direction. The plurality of processing light beams EL that have passed through the collector lenses 12 are incident on the plurality of collimator lenses 13. The collimator lenses 13 convert the processing light beams EL that have passed through the collector lenses 12 into parallel beams.

[0017] The optical isolator 14 is incident on a plurality of processing light beams EL that have passed through a plurality of collimator lenses 13. The optical isolator 14 transmits the plurality of processing light beams EL that have entered the optical isolator 14 from the plurality of collimator lenses 13. On the other hand, the optical isolator 14 blocks the processing light EL that has been reflected by the workpiece W1.

[0018] A plurality of cylindrical expanders 15 are arranged side by side in the Y direction in alignment with the plurality of collimator lenses 13. When the diffractive optical element 11 splits the processing light EL into three beams as shown in Fig. 1, three cylindrical expanders 15 may be arranged side by side in the Y direction. A plurality of processing light beams EL that have passed through the optical isolator 14 are incident on the plurality of cylindrical expanders 15. The cylindrical expanders 15 expand the width of the processing light EL that passes through the cylindrical expanders 15 in the X direction (see Fig. 2).

[0019] A plurality of beams of processing light EL that have passed through a plurality of cylindrical expanders 15 are incident on the cylindrical lens 16. The cylindrical lens 16 focuses each beam of processing light EL that passes through the cylindrical lens 16 in the Y direction. As a result, the cross-sectional shape of the processing light EL that enters the spatial light modulator 100 of the optical unit 20 becomes an ellipse whose width in the Y direction is smaller than its width in the X direction (see FIG. 3). The processing light EL that has an elliptical cross-sectional shape and enters the spatial light modulator 100 may also be referred to as a sheet-shaped processing light EL. The cylindrical expander 15 and cylindrical lens 16 that shape the beam cross-sectional shape of the processing light EL from the light source 5 into an ellipse may also be referred to as a shaping optical system.

[0020] The optical unit 20 receives a plurality of beams of processing light EL that have passed through the cylindrical lens 16. The optical unit 20 includes, in order from the light source 5 side, a spatial light modulation element unit 21, a lens array 23, and a Schlieren optical system 25. The spatial light modulation element unit 21 includes a plurality of spatial light modulation elements 100 stacked in the Y direction and a drive circuit 22. The plurality of spatial light modulation elements 100 may be disposed at the rear focal position of the collector lens 12. As shown in FIG. 1 , when the diffractive optical element 11 splits the processing light EL into three beams of light, the spatial light modulation element unit 21 may include three spatial light modulation elements 100 stacked in the Y direction. Details of the spatial light modulation elements 100 will be described later. The drive circuit 22 is electrically connected to a plurality of electrodes provided on the plurality of spatial light modulation elements 100 via wiring EW, and is capable of applying a voltage to each electrode of the spatial light modulation elements 100.

[0021] A plurality of processed light beams EL that have passed through the cylindrical lenses 16 are incident on the plurality of spatial light modulators 100. When no voltage is applied to each electrode of the spatial light modulator 100, the spatial light modulator 100 emits the processed light beam EL that has entered the spatial light modulator 100 as zeroth-order diffracted light toward the lens array 23. When a voltage is applied to each electrode of the spatial light modulator 100, the processed light beam EL that has entered the spatial light modulator 100 is diffracted to generate diffracted light beams of a predetermined order (e.g., +1st or −1st order). Furthermore, when a voltage is applied to some of the electrodes of the spatial light modulator 100, a portion of the processed light beam EL that has entered the spatial light modulator 100 is diffracted to generate diffracted light beams of a predetermined order.

[0022] 2, when a voltage is applied to an electrode located on the central side of the spatial light modulator 100, the spatial light modulator 100 emits, toward the lens array 23, diffracted light DL of a predetermined order generated by the diffraction of the central portion of the processed light EL having an elliptical (sheet-like) cross section that is incident on the spatial light modulator 100, and emits the light of the remaining portion of the processed light EL (portions on the end sides in the ±X directions) as zeroth-order diffracted light toward the lens array 23. Furthermore, when a voltage is applied to an electrode located on the end side of the spatial light modulator 100 in the +X direction (or the −X direction), the spatial light modulator 100 emits, toward the lens array 23, diffracted light of a predetermined order generated by the diffraction of the light of the end side of the processed light EL in the +X direction (or the −X direction) of the processed light EL that is incident on the spatial light modulator 100, and emits the light of the remaining portion of the processed light EL as zeroth-order diffracted light toward the lens array 23.

[0023] 2, when a voltage is applied to the electrodes of the spatial light modulation element 100, two diffracted lights DL (e.g., ±1st-order diffracted lights) are emitted from the spatial light modulation element 100 instead of the processed light EL (0th-order diffracted light), but this is not limited to this. For example, when a voltage is applied to the electrodes of the spatial light modulation element 100, one diffracted light (e.g., +1st-order diffracted light or −1st-order diffracted light) may be emitted from the spatial light modulation element 100 instead of the processed light EL (0th-order diffracted light). Furthermore, the diffracted light of a predetermined order may be, for example, +1st-order diffracted light or −1st-order diffracted light, as long as it is diffracted light of an order different from the 0th-order diffracted light.

[0024] The processing light EL or diffracted light DL emitted from the plurality of spatial light modulators 100 is incident on the lens array 23. As shown in FIG. 4 , the lens array 23 has a plurality of lenses 24 arranged in two directions, the X direction and the Y direction. Each lens 24 of the lens array 23 is generally composed of a lens (anamorphic lens) having different power in the X direction and the Y direction, and is aligned in the Y direction in alignment with the plurality of spatial light modulators 100. As shown in FIG. 1 , when the diffractive optical element 11 splits the processing light EL into three beams of light, each lens 24 of the lens array 23 may be aligned in the Y direction in alignment with the three spatial light modulators 100.

[0025] Furthermore, the lenses 24 of the lens array 23 are arranged in a row in the X direction within the X-direction width of the spatial light modulator 100. In the example shown in FIGS. 2 and 4 , three lenses 24 of the lens array 23 are arranged in a row in the X direction within the X-direction width of the spatial light modulator 100, and are aligned with the electrodes of the spatial light modulator 100, which are divided into three control groups. As a result, the lens array 23 divides the processing light EL incident on the lens array 23 into three in the X direction and causes the divided light to enter the Schlieren optical system 25. Also, as shown in FIG. 2 , the lens array 23 causes the diffracted light DL incident on the lens array 23 to enter the Schlieren optical system 25. Note that in the example shown in FIG. 2 , the processing light EL emitted from the lenses 24 on the ±X-direction end sides of the lens array 23 is shown as a chief ray and marginal rays (upper ray and lower ray).

[0026] 2 and 4, the lenses 24 of the lens array 23 are arranged in groups of three in the X direction, but this is not limited to this. The lenses 24 of the lens array 23 may be arranged in groups of five in the X direction within the range of the X-direction width of the spatial light modulation element 100, or in groups of two or more in the X direction. Furthermore, the lenses 24 of the lens array 23 may be arranged in a single row in the X direction, i.e., in a single line in the Y direction. Furthermore, the lens array 23 may not be provided, and the position of the intermediate image located on the front focal plane of the Schlieren optical system 25 may be aligned with the position of the exit end of the spatial light modulation element 100.

[0027] 1 and 2 , the Schlieren optical system 25 includes a first relay lens 26, an aperture stop 27, and a second relay lens 28, which are arranged in this order from the light source 5 side. The processing light EL or diffracted light DL that has passed through each lens 24 of the lens array 23 is incident on the first relay lens 26. The first relay lens 26 collects the multiple processing light beams EL that have entered the first relay lens 26 toward the center of the aperture stop 27.

[0028] The diaphragm 27 is disposed at the rear focal position of the first relay lens 26. An opening 27a is formed in the center of the diaphragm 27, through which the multiple beams of processing light EL that are transmitted through the first relay lens 26 and converge can pass. The diaphragm 27 blocks the diffracted light DL from the spatial light modulation element unit 21 that has transmitted through the first relay lens 26.

[0029] The plurality of processing light beams EL that have passed through the opening 27 a of the diaphragm 27 are incident on the second relay lens 28. The second relay lens 28 parallels the traveling directions of the plurality of processing light beams EL that pass through the second relay lens 28. The second relay lens 28 is positioned so that the front focal position of the second relay lens 28 is located at the rear focal position of the first relay lens 26.

[0030] The plurality of beams of processing light EL that have passed through the second relay lens 28 are incident on the condenser lens 29. The condenser lens 29 collects the plurality of beams of processing light EL that have entered the condenser lens 29 toward the galvanometer mirror 31 of the irradiation device 30. The condenser lens 29 may be positioned so that the front focal position of the condenser lens 29 is located at the rear focal position of the second relay lens 28.

[0031] A plurality of beams of processing light EL that have passed through the condenser lens 29 are incident on the irradiation device 30 (galvanometer mirror 31). The irradiation device 30 irradiates the workpiece W1 with the plurality of beams of processing light EL that have entered the irradiation device 30. As shown in FIG. 1 , the irradiation device 30 includes the galvanometer mirror 31 and a scanning optical system 35, which are arranged in this order from the light source 5 side.

[0032] The galvanometer mirror 31 changes the emission direction of the multiple processing light beams EL by swinging or rotating the reflecting surface to change the angle relative to the optical path of the processing light beam EL. The change in the emission direction of the multiple processing light beams EL by the galvanometer mirror 31 is converted into a change in the irradiation position of the multiple processing light beams EL by the scanning optical system 35. Therefore, by changing the emission direction of the multiple processing light beams EL by the galvanometer mirror 31, the irradiation position (focusing position) of the processing light beam EL on the workpiece W1 can be changed. This allows the galvanometer mirror 31 to scan the surface of the workpiece W1 with the multiple processing light beams EL. Note that instead of the galvanometer mirror 31, a polygon scanner, an acousto-optical element, or the like may be used to scan the surface of the workpiece W1 with the multiple processing light beams EL.

[0033] The processing light EL emitted from the galvanometer mirror 31 is incident on the scanning optical system 35. The scanning optical system 35 focuses the processing light EL from the galvanometer mirror 31 onto the surface of the workpiece W1. That is, the scanning optical system 35 irradiates the surface of the workpiece W1 with the processing light EL in a converged state.

[0034] The control device 40 is configured using, for example, a CPU (Central Processing Unit), a memory (not shown), etc. The control device 40 controls the operations of the light source 5, the drive circuit 22, the galvanometer mirror 31, etc. based on a control program stored in the memory.

[0035] In the optical processing apparatus 1 configured as described above, the processing light EL emitted from the light source 5 enters the processing optical system 10. The processing optical system 10 splits the processing light EL into multiple processing lights (e.g., nine processing lights arranged three by three) and emits them toward the irradiation device 30. The multiple processing lights EL emitted from the processing optical system 10 are irradiated onto the workpiece W1 via the galvanometer mirror 31 and scanning optical system 35 of the irradiation device 30. At this time, the galvanometer mirror 31 changes the emission direction of the multiple processing lights EL, thereby changing the irradiation position (focusing position) of the processing light EL relative to the workpiece W1. As a result, the galvanometer mirror 31 scans the surface of the workpiece W1 with the multiple processing lights EL.

[0036] In the processing optical system 10, multiple beams of processing light EL emitted from the diffractive optical element 11 are incident on the collector lens 12. The multiple beams of processing light EL that have passed through the collector lens 12 are incident on multiple collimator lenses 13. The multiple beams of processing light EL that have passed through the multiple collimator lenses 13 are incident on the optical isolator 14. The multiple beams of processing light EL that have passed through the optical isolator 14 are incident on multiple cylindrical expanders 15. The multiple beams of processing light EL that have passed through the multiple cylindrical expanders 15 are incident on the cylindrical lenses 16. The multiple beams of processing light EL that have passed through the cylindrical lenses 16 are incident on multiple spatial light modulators 100 of the optical unit 20 (spatial light modulator unit 21). The cross-sectional shape of the processing light EL that enters each spatial light modulator 100 is an ellipse whose width in the Y direction is smaller than its width in the X direction (see FIG. 3).

[0037] When no voltage is applied to the electrodes of the spatial light modulators 100, the processing light EL incident on the spatial light modulator 100 is emitted from the spatial light modulator 100 as zero-order diffracted light and enters the lens array 23. The processing light EL (e.g., nine processing light beams EL arranged in groups of three in the X and Y directions) that are split after passing through the lenses 24 of the lens array 23 are temporarily focused at the focal position (position of the first intermediate image IM1) of the lens array 23 to form multiple (nine) discrete focused beams. The processing light EL that has been temporarily focused at the focal position of the lens array 23 enters the first relay lens 26 of the Schlieren optical system 25. The processing light EL that has passed through the first relay lens 26 passes through the opening 27a of the diaphragm 27 and enters the second relay lens 28. The plurality of processing light beams EL that have passed through the second relay lens 28 are re-focused at the rear focal position (position of the second intermediate image IM2) of the second relay lens 28 to form a plurality (nine) of discrete focused beams. The plurality of processing light beams EL that have been re-focused at the rear focal position of the second relay lens 28 are incident on the focusing lens 29. The plurality of processing light beams EL that have passed through the focusing lens 29 are collected by the galvanometer mirror 31 of the irradiation device 30.

[0038] When a voltage is applied to each electrode of the spatial light modulator 100, the processed light EL incident on the spatial light modulator 100 is diffracted, generating diffracted light of a predetermined order. Furthermore, when a voltage is applied to electrodes of a control group corresponding to some of the lenses 24 of the lens array 23 in the spatial light modulator 100, a portion of the processed light EL incident on the spatial light modulator 100 is diffracted, generating diffracted light of a predetermined order. For example, when a voltage is applied to electrodes of a control group corresponding to the central lens 24 of the lens array 23 in the spatial light modulator 100, the central portion of the processed light EL, which has an elliptical (sheet-like) cross section and is incident on the spatial light modulator 100, is diffracted with a diffraction efficiency corresponding to the applied voltage, and diffracted light DL of a predetermined order is emitted from the spatial light modulator 100. At this time, a portion of the central portion of the processed light EL is emitted from the spatial light modulator 100 as zeroth-order diffracted light. When an appropriate voltage that results in a diffraction efficiency of 100% is applied to the electrodes, all of the light in the central portion of the processing light EL is diffracted, and diffracted light DL of a predetermined order (zeroth-order diffracted light is not emitted) is emitted from the spatial light modulator 100. Furthermore, when a voltage is applied to the electrodes of the control group corresponding to the central lens 24 of the lens array 23 in the spatial light modulator 100 and no voltage is applied to the electrodes of the control group corresponding to the lenses 24 on both ends of the lens array 23, the light in the other portions of the processing light EL (portions on the ends in the ±X directions) is emitted from the spatial light modulator 100 as zeroth-order diffracted light.

[0039] The diffracted light DL emitted from the spatial light modulator 100 passes through the lens array 23, travels at an inclination in the X direction relative to the optical axis of the processing optical system 10, and enters the first relay lens 26 of the Schlieren optical system 25. The diffracted light DL traveling at an inclination relative to the optical axis of the processing optical system 10 and transmitted through the first relay lens 26 is blocked by the aperture 27. In other words, the processing light EL is diffracted by the spatial light modulator 100 and attenuated by the aperture 27. As a result, by applying a voltage to at least some of the electrodes of the spatial light modulator 100, at least one of the multiple processing light beams EL (e.g., nine processing light beams arranged three by three) can be selected and prevented from being irradiated onto the workpiece W1 (when a voltage is applied to the electrodes such that the diffraction efficiency is 100%). Furthermore, the intensity of some of the multiple processing light beams EL can be continuously or stepwise changed to irradiate the workpiece W1.

[0040] Therefore, by controlling the drive circuit 22 with the control device 40 and changing which of the multiple electrodes provided on the multiple spatial light modulators 100 to which voltage is applied, it is possible to selectively change the processing light EL irradiated onto the workpiece W1 in a short period of time. Furthermore, the intensity of the processing light irradiated onto the workpiece W1 can also be changed continuously or stepwise. Therefore, with the optical processing device 1 equipped with the optical unit 20 (spatial light modulator 100), the shape of the processing light irradiated onto the workpiece W1 can be changed in a short period of time within the range in which the voltage can be controlled, enabling a wider variety of processing to be performed.

[0041] A shaping optical system (cylindrical expander 15 and cylindrical lens 16) may also be provided to shape the cross-sectional beam shape of the processing light EL from light source 5 into an elliptical shape. This allows spatial light modulator 100 to emit diffracted light DL of a predetermined order, which is generated by diffracting a portion of the processing light EL having an elliptical cross-section that is incident on spatial light modulator 100, and emit the remaining portion of the processing light EL as zeroth-order diffracted light. Therefore, using a relatively small number of spatial light modulators 100, it is possible to selectively change the processing light EL to be irradiated onto workpiece W1 from among multiple processing light EL (e.g., nine processing light beams arranged in a matrix of three vertically and three horizontally).

[0042] Note that, although the configuration is such that the zeroth-order diffracted light emitted from the spatial light modulation element 100 passes through the opening 27a of the diaphragm 27 and the diffracted light of a predetermined order emitted from the spatial light modulation element 100 is blocked by the diaphragm 27, the present invention is not limited to this. For example, the configuration may be such that the diffracted light of a predetermined order emitted from the spatial light modulation element 100 passes through the opening 27a of the diaphragm 27 and the zeroth-order diffracted light emitted from the spatial light modulation element 100 is blocked by the diaphragm 27. Furthermore, instead of the diaphragm 27, a neutral density filter having an opening in its center may be provided so that the amount of diffracted light is significantly reduced by the neutral density filter. The diaphragm 27 that blocks diffracted light and the neutral density filter that reduces the amount of diffracted light can also be considered as neutral density units that attenuate diffracted light.

[0043] In the above-described optical processing device 1, the Schlieren optical system 25 between the lens array 23 and the condenser lens 29 may be omitted. In this case, a light-attenuating unit that attenuates the diffracted light of a predetermined order emitted from the spatial light modulator 100 may be provided in the galvanometer mirror 31, on which the plurality of processing lights EL are converged by the condenser lens 29. As such a light-attenuating unit, for example, a galvanometer mirror having a reflecting surface of a size or shape that prevents the diffracted light of a predetermined order emitted from the spatial light modulator 100 from entering may be used.

[0044] [Modifications of Optical Processing Apparatus] The optical processing apparatus equipped with the spatial light modulator 100 is not limited to the optical processing apparatus 1 that performs subtractive processing described above, but may also be an optical processing apparatus 51 (see FIG. 5) that performs additive processing. As shown in FIG. 5, the optical processing apparatus 51 according to a first modification includes a light source 5, a processing optical system 10, an irradiation device 30, a control device 40, and a supply mechanism 55. The optical processing apparatus 51 performs additive processing by irradiating a modeling material M1 supplied by the supply mechanism 55 with processing light EL to form a three-dimensional object SC. The modeling material M1 is formed in powder form using, for example, a metal material such as titanium or stainless steel, a resin material such as engineering plastic, or a ceramic material.

[0045] The light source 5, processing optical system 10, irradiation device 30, and control device 40 have the same configurations as the light source 5, processing optical system 10, irradiation device 30, and control device 40 of the optical processing device 1 described above, and therefore the same reference numerals are used and detailed description thereof is omitted. The light source 5 may be a laser light source that emits pulsed light as the processing light EL. In this case, the pulsed light may have a pulse width longer than that of a femtosecond laser. The wavelength of the processing light EL may be in the infrared wavelength range (e.g., 1064 nm).

[0046] The supply mechanism 55 includes a build piston 56A and a build cylinder 56B, a feed piston 57A and a feed cylinder 57B, and a leveling roller 58. The build piston 56A and the build cylinder 56B are disposed below the scanning optical system 35. The build piston 56A is attached inside the build cylinder 56B so as to be able to reciprocate up and down. The feed piston 57A and the feed cylinder 57B are disposed side by side with the build piston 56A and the build cylinder 56B. The feed piston 57A is disposed inside the feed cylinder 57B so as to be able to reciprocate up and down. The modeling material M1 is stored above the feed piston 57A inside the feed cylinder 57B. The leveling roller 58 is disposed so as to be able to reciprocate in a substantially horizontal direction between the upper edge of the feed cylinder 57B and the upper edge of the build cylinder 56B. The leveling roller 58 rolls from the upper edge of the feed cylinder 57B to the upper edge of the build cylinder 56B, thereby pushing the modeling material M1 stored above the feed piston 57A outward and supplying it above the build piston 56A. The control device 40 controls the operation of the supply mechanism 55 in addition to the light source 5, the drive circuit 22, the galvanometer mirror 31, etc. The supply mechanism 55 may also include a squeegee instead of the leveling roller 58.

[0047] In the optical processing apparatus 51 according to the first modification, the supply mechanism 55 repeatedly supplies a layer of the modeling material M1 having a predetermined thickness above the build piston 56A inside the build cylinder 56B each time the processing light EL is irradiated. At this time, the build piston 56A moves downward by a distance equal to the predetermined thickness, and the feed piston 57A moves upward together with the modeling material M1 stored above the feed piston 57A. The leveling roller 58 then pushes the modeling material M1 protruding from the upper edge of the feed cylinder 57B above the build piston 56A. This results in a layer of the modeling material M1 having a predetermined thickness being supplied above the build piston 56A inside the build cylinder 56B. The predetermined thickness is the thickness of the modeling material M1 that can form part of a three-dimensional model SC by irradiation with the processing light EL.

[0048] As in the case of the optical processing apparatus 1 described above, the processing light EL emitted from the light source 5 enters the processing optical system 10. The processing optical system 10 splits the processing light EL into multiple processing lights (e.g., nine processing lights arranged three by three) and emits them toward the irradiation device 30. The multiple processing light lights EL emitted from the processing optical system 10 are irradiated onto the top layer of the modeling material M1 supplied above the build piston 56A inside the build cylinder 56B via the galvanometer mirror 31 and scanning optical system 35 of the irradiation device 30. At this time, the galvanometer mirror 31 changes the emission direction of the multiple processing light lights EL, thereby changing the irradiation position (focusing position) of the processing light EL relative to the modeling material M1. As a result, the galvanometer mirror 31 scans the top layer of the modeling material M1 with the multiple processing light lights EL.

[0049] As described above, the light source 5, processing optical system 10, irradiation device 30, and control device 40 are configured similarly to the light source 5, processing optical system 10, irradiation device 30, and control device 40 of the optical processing apparatus 1 described above. Therefore, similar to the optical processing apparatus 1 described above, the control device 40 controls the drive circuit 22 to change the electrodes to which voltage is applied among the multiple electrodes provided on the multiple spatial light modulators 100, thereby selectively changing the processing light EL (e.g., nine processing lights arranged three by three) irradiated onto the shaping material M1 in a short period of time. Furthermore, the intensity of the processing light irradiated onto the shaping material M1 can be changed continuously or stepwise. Therefore, the same effects as those of the optical processing apparatus 1 described above can be obtained.

[0050] Furthermore, the optical processing device equipped with the spatial light modulator 100 may be an optical processing device 61 (see FIG. 6 ) capable of forming a shaped object by laser metal deposition (LMD) as an additional processing method. As shown in FIG. 6 , the optical processing device 61 according to the second modification includes a shaping head 71, a head drive system 76, a stage 81, a measuring device 86, and a control device 91. The optical processing device 61 irradiates a shaping material M2 supplied from a supply nozzle 73 of the shaping head 71 with processing light EL, and performs additional processing on the workpiece W2 to form a three-dimensional shaped object.

[0051] The optical processing device 61 forms a three-dimensional object on a workpiece W2, which serves as a base (i.e., a base material) for forming the object. When the workpiece W2 is the stage 81, the optical processing device 61 can form a three-dimensional object on the stage 81. The forming material M2 is a material that can be melted by irradiation with processing light EL of a predetermined intensity or higher. The forming material M2 is formed into a powder or granular form using, for example, at least one of a metal material and a resin material.

[0052] The modeling head 71 includes an irradiation unit 72 and a supply nozzle 73. The irradiation unit 72 includes a processing optical system (not shown) and an irradiation device (not shown). The processing optical system and irradiation device of the irradiation unit 72 have the same configurations as the processing optical system 10 and irradiation device 30 of the optical processing apparatus 1 described above. That is, the irradiation unit 72 is provided with an optical unit and a spatial light modulator similar to the optical unit 20 and spatial light modulator 100 described above. The irradiation unit 72 is optically connected to a light source (not shown) via an optical transmission member (not shown) such as an optical fiber. The light source emits processing light EL, such as laser light. The wavelength range of the processing light EL may be, for example, the wavelength range of visible light, infrared light, or ultraviolet light. The irradiation unit 72 splits the processing light EL transmitted from the light source via the optical transmission member into multiple processing light beams and irradiates them downward.

[0053] A stage 81 is disposed below the irradiation unit 72. When the workpiece W2 is held on the stage 81, the irradiation unit 72 can irradiate (plural) processing light beams EL toward the workpiece W2. Specifically, the irradiation unit 72 irradiates the processing light EL onto an irradiation area EA of a predetermined shape that is set on the workpiece W2 as an area to be irradiated (focused) with the processing light.

[0054] The supply nozzle 73 supplies the modeling material M2 from a supply port 74 formed at the tip of the supply nozzle 73. Specifically, the supply nozzle 73 sprays, ejects, or injects the modeling material M2 from the supply port 74 formed at the tip of the supply nozzle 73. The supply nozzle 73 is physically connected to a material supply device (not shown), which is a supply source of the modeling material M2, via a material conveying member (not shown) such as a pipe. The supply nozzle 73 supplies the modeling material M2 conveyed from the material supply device via the conveying member downward.

[0055] A stage 81 is disposed below the supply nozzle 73. When the workpiece W2 is held on the stage 81, the supply nozzle 73 can irradiate the workpiece W2 with the modeling material M2. The supply nozzle 73 is aligned with the irradiation unit 72 so that the supply nozzle 73 supplies the modeling material M2 toward the irradiation area EA onto which the irradiation unit 72 irradiates the processing light EL. That is, the supply nozzle 73 and the irradiation unit 72 are aligned so that the supply area MA, which is set on the workpiece W2 as the area onto which the supply nozzle 73 supplies the modeling material M2, coincides with (or at least partially overlaps with) the irradiation area EA.

[0056] The head drive system 76 is configured using, for example, a motor. The head drive system 76 moves the object-forming head 71 in three-dimensional directions. By moving the object-forming head 71, the head drive system 76 can change the positional relationship between the workpiece W2 and the irradiation area EA. Furthermore, by moving the object-forming head 71, the head drive system 76 can change the positional relationship between the workpiece W2 and the supply area MA.

[0057] The stage 81 removably holds the workpiece W2 on an upper surface 82 that can face the modeling head 71. The measuring device 86 measures the state of the measurement object on the stage 81. The measurement object may include the workpiece W2 and a test mark (not shown) formed on the stage 81. The measurement object measures the position of the measurement object on the stage 81 as an example of the state of the measurement object. For example, the measurement object may measure the absolute position of the test mark on the stage 81. The measurement object may also measure the relative position of the test mark with respect to the workpiece W2 on the stage 81.

[0058] The control device 91 is configured using, for example, a CPU (central processing unit), a memory (not shown), etc. The control device 91 controls the operations of the irradiation unit 72, the supply nozzle 73, the head drive system 76, the measurement device 86, etc. based on a control program stored in the memory.

[0059] In the optical processing apparatus 61 according to the second modification, as described above, the processing optical system and the irradiation device of the irradiation unit 72 are configured similarly to the processing optical system 10 and the irradiation device 30 of the optical processing apparatus 1 described above. Therefore, similar to the optical processing apparatus 1 described above, the control device 91 controls a voltage generator (not shown) to change the electrode to which voltage is applied among the multiple electrodes provided on the multiple spatial light modulators, thereby selectively changing the processing light irradiated onto the shaping material M2 among the multiple processing light beams (e.g., nine processing light beams arranged three by three vertically and horizontally) in a short period of time. Furthermore, the intensity of the processing light irradiated onto the shaping material M2 can be changed continuously or stepwise. Therefore, the same effects as those of the optical processing apparatus 1 described above can be achieved.

[0060] First Embodiment Next, a spatial light modulation element 100 according to the first embodiment will be described. The spatial light modulation element 100 according to the first embodiment is a line-type (also referred to as a linear type) electro-optic spatial light modulation element, and has a configuration advantageous for Raman-Nath diffraction. As shown in FIGS. 7 to 9 , the spatial light modulation element 100 according to the first embodiment includes an optical element 110, multiple positive electrodes 120, multiple negative electrodes 125, multiple positive wires 130, and multiple negative wires 135. The spatial light modulation element 100 modulates and emits sheet-shaped processing light EL having a cross-sectional shape shaped into a flattened ellipse. In the first embodiment, the directions indicated by the arrows in FIG. 7 may be referred to as the X direction, Y direction, and Z direction, respectively. The X direction, Y direction, and Z direction are perpendicular to each other.

[0061] The optical element 110 is formed in a flat rectangular parallelepiped shape using a light-transmitting ferroelectric material. A ferroelectric is a type of dielectric, an optical crystal in which electric dipoles are aligned even in the absence of an external electric field, and the dipole direction can be changed by an electric field. Examples of light-transmitting ferroelectric materials include lithium niobate (lithium niobate), lithium tantalate (lithium tantalate), MgO:LN (MgO-doped lithium niobate), and MgO:SLT (MgO-doped stoichiometric lithium tantalate). An incident surface 111 is formed at one end (negative Z direction) of the optical element 110. A sheet-shaped (elliptical cross-sectional shape) processing light EL traveling in the Z direction is incident on the incident surface 111 as incident light. The Z direction may also be referred to as a first axis direction, and the incident surface 111 may intersect with the first axis. An exit surface 112 is formed at the end (in the +Z direction) of the optical member 110 opposite the entrance surface 111. Light that enters the optical member 110 from the entrance surface 111 exits from the exit surface 112.

[0062] An arrangement surface 113 on which positive and negative electrodes 120, 125 are arranged is formed on a side surface on the +Y direction side of the optical element 110. Multiple pairs of positive and negative electrodes 120, 125 are arranged along the X direction on the arrangement surface 113. The positive and negative electrodes 120, 125 are formed using a metal material containing, for example, gold (Au). A buffer layer 114 (see FIG. 10 ) is formed between the arrangement surface 113 and the multiple pairs of positive and negative electrodes 120, 125. The buffer layer 114 is formed using, for example, silicon dioxide (SiO ). The X direction may be referred to as a second axis direction, and the Y direction may be referred to as a third axis direction. The arrangement surface 113 may also intersect with the third axis.

[0063] The optical element 110 has a periodically poled structure. The optical element 110 includes a plurality of first polarized portions 115 extending in the Z direction and a plurality of second polarized portions 116 extending in the Z direction adjacent to the first polarized portions 115, arranged alternately along the X direction. For example, when three lenses 24 of the lens array 23 of the optical processing device are arranged side by side in the X direction, the optical element 110 may have at least 18 first and second polarized portions 115, 116. When five lenses 24 of the lens array 23 of the optical processing device are arranged side by side in the X direction, the optical element 110 may have at least 30 first and second polarized portions 115, 116. The second polarized portions 116 are polarized in a different direction (specifically, the opposite direction) from the first polarized portions 115. To provide the optical element 110 with a periodic polarization inversion structure, the polarization direction of the portion corresponding to the second polarization portion 116 of an optical element formed in a rectangular parallelepiped shape with uniform polarization (dielectric polarization) is inverted by 180°. For example, when using a known method known as the "electric field application method," an electrode is attached to the portion corresponding to the second polarization portion 116, and a voltage above a certain level (also referred to as a polarization inversion voltage or coercive field) is applied to invert the polarization direction of the second polarization portion 116. Note that the polarization direction of the first polarization portion 115 may also be inverted, not limited to the second polarization portion 116.

[0064] A pair of positive and negative electrodes 120, 125 is provided in each portion of the placement surface 113 where the first polarized portion 115 is located. In the portion of the placement surface 113 where the first polarized portion 115 is located, the positive and negative electrodes 120, 125 are formed extending parallel to the Z direction from one end side to the other end side of the first polarized portion 115. The negative electrode 125 is arranged adjacent to the positive electrode 120 on the +X direction side. The positive and negative electrodes 120, 125 of the first polarized portion 115 may also be referred to as first and second electrodes.

[0065] Furthermore, pairs of positive and negative electrodes 120, 125 are provided in the portions of the arrangement surface 113 where the second polarized portions 116 are located. In the portions of the arrangement surface 113 where the second polarized portions 116 are located, the positive and negative electrodes 120, 125 are formed extending parallel to the Z direction from one end side to the other end side of the second polarized portion 116. Furthermore, the negative electrode 125 is arranged adjacent to the positive electrode 120 on the +X direction side. The positive and negative electrodes 120, 125 of the second polarized portion 116 may also be referred to as third and fourth electrodes.

[0066] The multiple positive electrodes 120 are individually electrically connected to multiple positive wires 130. The multiple positive wires 130 are electrically connected to the drive circuit 22 described above. The multiple positive wires 130 apply voltages supplied from the drive circuit 22 to the multiple positive electrodes 120 individually. By applying a voltage to the positive electrodes 120 via the positive wires 130, a potential difference can be created between adjacent positive and negative electrodes 120, 125. The multiple negative electrodes 125 are individually electrically connected to multiple ground wires 135. The multiple ground wires 135 are electrically connected to the drive circuit 22. The multiple positive wires 130 and the multiple ground wires 135 constitute the wiring EW described above.

[0067] 8 and 9, in the spatial light modulation element 100 configured as described above, sheet-shaped (elliptical in cross section) processed light EL is incident as incident light on the incident surface 111 of the optical element 110. When no voltage is applied to the positive and negative electrodes 120, 125, the sheet-shaped processed light EL that enters the optical element 110 from the incident surface 111 is totally reflected at the positions of the positive and negative electrodes 120, 125 on the arrangement surface 113 and emerges from the emergence surface 112 as zero-order diffracted light.

[0068] As shown in Figure 10, when a voltage (lower than the aforementioned polarization inversion voltage) is applied to the positive electrode 120 via the positive wire 130, a potential difference is generated between the adjacent positive and negative electrodes 120, 125, and an electric field is generated inside the optical element 110, directed from the positive electrode 120 to the negative electrode 125. As described above, the optical element 110 has a periodically polarization inversion structure. In Figure 10, the polarization directions in the first polarization portion 115 and the second polarization portion 116 are schematically indicated by thick arrows. The graph shown in Figure 10 also shows changes in the refractive index in the first polarization portion 115 and the second polarization portion 116.

[0069] When a voltage is applied to the positive electrode 120 in the portion of the placement surface 113 where the first polarization portion 115 is located, an electric field is generated from the positive electrode 120 toward the first polarization portion 115, and the electric field gradually changes direction and moves toward the negative electrode 125. As the electric field moves from the positive electrode 120 toward the negative electrode 125, the refractive index inside the first polarization portion 115 changes due to the electro-optic effect. The refractive index of the region inside the first polarization portion 115 near the placement surface 113 changes along the X direction, for example, so that the refractive index is higher at a position closer to the positive electrode 120 and lower at a position closer to the negative electrode 125.

[0070] When a voltage is applied to the positive electrode 120 in a portion of the placement surface 113 where the second polarization portion 116 is located, an electric field is generated from the positive electrode 120 toward the second polarization portion 116, and the electric field gradually changes direction toward the negative electrode 125. As the electric field moves from the positive electrode 120 toward the negative electrode 125, the refractive index within the second polarization portion 116 changes due to an electro-optic effect. The second polarization portion 116 is polarized in a different direction (specifically, the opposite direction) from the first polarization portion 115. Therefore, the refractive index of a region within the second polarization portion 116 near the placement surface 113 changes along the X direction, for example, becoming lower toward the positive electrode 120 and higher toward the negative electrode 125. A diffraction grating 117 having a pitch direction along the X direction is generated in the region where the refractive index changes within the optical element 110 (the first polarization portion 115 and the second polarization portion 116).

[0071] When a voltage is applied to the positive electrode 120, the sheet-like processed light EL incident on the incident surface 111 and entering the optical element 110 is diffracted by Raman-Nath diffraction in the region where the diffraction grating 117 is generated (i.e., the region where the refractive index is changed). The diffracted light DL (e.g., ±1st-order diffracted light) generated by Raman-Nath diffraction is totally reflected at the positions of the positive and negative electrodes 120, 125 on the arrangement surface 113 and emitted from the emission surface 112. In this way, the spatial light modulator 100 modulates the processed light EL incident on the incident surface 111 of the optical element 110 by the potential difference between the adjacent positive and negative electrodes 120, 125, and emits the diffracted light DL from the emission surface 112.

[0072] Here, a conventional spatial light modulation element will be described. The conventional spatial light modulation element 150 illustrated in Figures 11 to 13 is a line-type electro-optic spatial light modulation element that uses total internal reflection (TIR). A spatial light modulation element that uses total internal reflection (TIR) ​​is disclosed in, for example, U.S. Patent No. 6,169,565. The conventional spatial light modulation element 150 includes an optical member 160, a plurality of positive electrodes 170, and a plurality of negative electrodes 175.

[0073] The optical element 160 is formed in a flat rectangular parallelepiped shape using a translucent ferroelectric material. The optical element 160 has an incident surface 161, an exit surface 162, and an arrangement surface 163. Sheet-shaped (elliptical in cross section) processing light EL enters the incident surface 161 as incident light. The light entering the optical element 160 from the incident surface 161 exits from the exit surface 162. Multiple positive and negative electrodes 170, 175 are arranged on the arrangement surface 163. The positive and negative electrodes 170, 175 are formed using a metal material containing, for example, gold (Au). A buffer layer 164 is formed between the arrangement surface 163 and the multiple pairs of positive and negative electrodes 170, 175. The buffer layer 164 is formed using, for example, silicon dioxide (SiO2). The positive electrode 170 is electrically connected to a positive wire (not shown). The negative electrode 175 is electrically connected to a ground line (not shown).

[0074] When a voltage is applied to the positive electrode 170, an electric field is generated from the positive electrode 170 toward the optical element 160, and the electric field gradually changes direction and moves toward the negative electrode 175. As the electric field moves from the positive electrode 170 to the negative electrode 175, the refractive index within the optical element 160 changes due to an electro-optic effect. A diffraction grating 167 is generated in the region of the optical element 160 where the refractive index changes. In a conventional spatial light modulation element 150, for example, if the positive and negative electrodes 170, 175 formed of gold (Au) are disposed on a buffer layer 164 having a thickness of approximately 1 μm, the penetration depth of the electric field into the optical element 160 can be maximized by setting the distance between the positive and negative electrodes 170, 175 to approximately 20 μm. FIG. 13 schematically illustrates a conventional spatial light modulation element 150 when the distance between the positive and negative electrodes 170, 175 is 20 μm. 13, thick arrows schematically indicate the direction of polarization (dielectric polarization) in the optical member 160. The graph shown in FIG.

[0075] As shown in Figure 14, when the distance between the positive and negative electrodes 170, 175 is narrower than 20 μm, the penetration depth of the electric field becomes shallower. On the other hand, as shown in Figure 15, when the distance between the positive and negative electrodes 170, 175 is wider than 20 μm, the penetration depth of the electric field does not change significantly. However, although a uniform electric field is required on the surfaces of the positive and negative electrodes 170, 175, the electric field concentrates at the edges of the positive and negative electrodes 170, 175, and the electric field decreases in the central portions of the positive and negative electrodes 170, 175, so the desired change in refractive index cannot be obtained.

[0076] Here, the wavelength of the incident light (processing light) is λ, the period (grating pitch) of the diffraction grating is Λ, the thickness (interaction length) of the diffraction grating is L, and the refractive index of the crystal (optical member) at wavelength λ is n. The tendency of diffraction caused by the interaction between the incident light and the diffraction grating is expressed as the Q parameter by the following equation (1).

[0077]

[0078] In equation (1), it is known that the diffraction of light when Q > 10 is Bragg diffraction, and the diffraction of light when Q < 1 is Raman-Nath diffraction. In a conventional spatial light modulator 150, if the distance between the positive and negative electrodes 170, 175 is 20 μm, the period Λ of the diffraction grating 167 is 40 μm. Here, the wavelength λ of the incident light (processing light) is 1 μm, and the refractive index n of the crystal (optical element 160) at wavelength λ (λ = 1 μm) is 2.2. In this case, to generate a Raman-Nath diffraction type diffraction grating in the conventional spatial light modulator 150, equation (1) indicates that the thickness (interaction length) L of the diffraction grating 167 must be less than 0.56 mm. As a result, it can be seen that the thickness of the diffraction grating 167 can only be approximately 0.5 mm.

[0079] In contrast, the spatial light modulation element 100 according to the first embodiment has a periodic polarization inversion structure, and the manner in which the refractive index changes due to the potential difference between the positive and negative electrodes 120, 125 is reversed between the first polarization portion 115 and the second polarization portion 116. Therefore, in the spatial light modulation element 100 according to the first embodiment, if the distance between the positive and negative electrodes 120, 125 is 20 μm, the period Λ of the diffraction grating 117 is 80 μm. That is, the period of the diffraction grating 117 in the spatial light modulation element 100 according to the first embodiment is twice the period of the diffraction grating 167 in the conventional spatial light modulation element 150. Note that a periodic polarization inversion structure with a period of 80 μm and a duty ratio of 1:1 can be easily fabricated due to its relatively long period. Here, the wavelength λ of the incident light (processing light) is assumed to be 1 μm, and the refractive index n of the crystal (optical element 110) at the wavelength λ (λ = 1 μm) is assumed to be 2.2. In this case, to generate a Raman-Nath diffraction grating in the spatial light modulation element 100 according to the first embodiment, the thickness (interaction length) L of the diffraction grating 117 should be set to be less than 2.24 mm according to formula (1). As a result, the thickness of the diffraction grating 117 that can be generated by the spatial light modulation element 100 according to the first embodiment is approximately 2.2 mm, which is approximately four times the thickness of the diffraction grating 167 that can be generated by the conventional spatial light modulation element 150.

[0080] In addition, the diffraction efficiency of Raman-Nath diffraction, η ｑ is expressed by the following equation (2).

[0081]

[0082] In formula (2), J ｑ (2κL) indicates the Bessel function (q=0, ±1, ±2, ±3, ...) of the thickness (interaction length) L of the diffraction grating. Also, κ is expressed by the following equation (3).

[0083]

[0084] In formula (3), Δn ｅ is expressed by the following equation (4).

[0085]

[0086] In formula (4), n ｅ is the refractive index of the crystal (optical element) at wavelength λ. ３３ is the Pockels constant; g is the electrode spacing distance; c is the conversion factor of the electric field penetration depth; and V is the voltage applied to the electrodes.

[0087] As can be seen from equation (2), the diffraction efficiency is proportional to the square of the Bessel function of the diffraction grating thickness (interaction length) L. Therefore, when using the spatial light modulator 100 according to the first embodiment, the desired diffraction efficiency can be obtained with approximately one-quarter the voltage required when using the conventional spatial light modulator 150. Furthermore, since the desired diffraction efficiency can be obtained with a low voltage, the burden on the drive circuit is reduced, and the processing light EL can be modulated at high speed. The voltage required to obtain the desired diffraction efficiency is approximately 80 V for the conventional spatial light modulator 150, while it is approximately 20 V, or one-quarter, for the spatial light modulator 100 according to the first embodiment. Thus, by adding an easily fabricated long-period polarization reversal structure to the optical element 110 formed using a ferroelectric material, the drive voltage required to obtain the desired diffraction efficiency can be reduced, enabling the processing light EL to be modulated at high speed.

[0088] Spatial light modulators with electrodes on both sides of an optical element are also known, as disclosed in, for example, Japanese Patent No. 5058935. In such spatial light modulators, electrodes are provided on both sides of a thin optical element, and by applying a voltage to each electrode, an electric field can be transmitted throughout the entire thickness of the optical element. This eliminates the need to consider the penetration depth of the electric field, compared to conventional spatial light modulators 150 with electrodes on one side of the optical element. Even in Raman-Nath diffraction gratings with a short interaction length L, the strength of the electric field can be increased by thinning the optical element. This allows for a lower drive voltage to achieve the desired diffraction efficiency, enabling high-speed modulation of the processed light EL.

[0089] However, when a spatial light modulator having electrodes on both sides of an optical element is applied to an optical processing device using high-power laser light, the optical power density increases within the thin optical element, making it difficult to use a material with low optical power resistance. Furthermore, it is necessary to thin the optical element, provide electrodes on both sides of the optical element, and bond a reinforcing member to the thinned optical element, making manufacturing the spatial light modulator difficult. In contrast, when the spatial light modulator 100 according to the first embodiment is used, the positive and negative electrodes 120, 125 are provided only on one side (the placement surface 113) of the optical element 110, allowing the optical element 110 to be thicker. This suppresses the increase in optical power density within the optical element 110, even when high-power laser light is used as the processing light EL. Since the positive and negative electrodes 120, 125 are provided on only one side of the optical element 110, there is no need to thin the optical element 110, lay electrodes on both sides of the optical element 110, or join reinforcing members to thin the optical element 110, making it easier to manufacture the spatial light modulation element.

[0090] Furthermore, as disclosed in the literature "Masahide Okazaki and Toshiaki Suhara, "High-performance 1024-pixel EO spatial light modulator using cascaded periodically-poled Raman-Nath gratings," IEEE / OSA Journal of Lightwave Technology, vol. 33, no. 24, pp. 5195-5200, Nov. 2015," independently modulating a portion of the incident light requires, taking into account the divergence angle of the light source, three or more periods of refractive index change in the diffraction grating, i.e., in the first embodiment, at least six pairs of positive and negative electrodes must be collectively controlled. In the spatial light modulation element 100 according to the first embodiment, the multiple positive electrodes 120 are individually electrically connected to the drive circuit 22 via multiple positive lines 130. The multiple negative electrodes 125 are individually electrically connected to the drive circuit 22 via multiple ground lines 135. The drive circuit 22 independently controls the voltage for each control group consisting of at least six pairs of positive and negative electrodes 120, 125, so that a portion of the incident light (processed light EL) can be independently modulated.

[0091] For example, when three lenses 24 of the lens array 23 of the optical processing device are arranged side by side in the X direction, applying a voltage to the positive electrodes 120 of the first to sixth pairs of positive and negative electrodes 120, 125 counting from the bottom of the paper in Fig. 7 may independently modulate the light in the end 1 / 3 portion of the sheet-like processing light EL in the -X direction, and emit diffracted light DL from the emission surface 112. Applying a voltage to the positive electrodes 120 of the seventh to twelfth pairs of positive and negative electrodes 120, 125 counting from the bottom of the paper in Fig. 7 may independently modulate the light in the central 1 / 3 portion of the sheet-like processing light EL, and emit diffracted light DL from the emission surface 112. By applying a voltage to the positive electrodes 120 of the 13th to 18th pairs of positive and negative electrodes 120, 125 counting from the bottom of the paper in Figure 7, the light in the 1 / 3 portion of the sheet-shaped processing light EL on the end side in the +X direction can be independently modulated, and diffracted light DL can be emitted from the emission surface 112.

[0092] [Characteristic Configuration of First Embodiment] The spatial light modulation element 100 according to the first embodiment includes an optical element 110 formed using a light-transmitting ferroelectric material, on which processing light EL traveling along the Z direction (first axis) is incident as incident light, positive and negative electrodes 120, 125 arranged on a placement surface 113 of the optical element 110 along the X direction (second axis), and wiring (a positive line 130 and a ground line 135) that applies a voltage to the positive electrode 120 so as to create a potential difference between the positive and negative electrodes 120, 125. In other words, the spatial light modulation element 100 according to the first embodiment includes the optical element 110 and the positive and negative electrodes 120, 125, and when a potential difference is generated between the positive and negative electrodes 120, 125, the refractive index within the optical element 110 changes along the X direction.

[0093] This enables high-speed modulation of the processing light EL (incident light) by modulating the processing light EL using the potential difference between the positive and negative electrodes 120, 125. Furthermore, since the positive and negative electrodes 120, 125 are provided only on one side (the placement surface 113) of the optical element 110, the optical element 110 can be made thicker, and even when high-power laser light is used as the processing light EL, an increase in the optical power density within the optical element 110 can be suppressed. Since the positive and negative electrodes 120, 125 are provided only on one side of the optical element 110, there is no need to thin the optical element 110, install electrodes on both sides of the optical element 110, or bond a reinforcing member to thin the optical element 110, facilitating the manufacture of a spatial light modulator. The positive and negative electrodes 120, 125 may be arranged adjacent to each other along the X direction. The placement surface 113 of the optical element 110 may intersect with the Y axis (third axis).

[0094] The optical element 110 also has a first polarization portion 115 extending along the Z direction and a second polarization portion 116 extending along the Z direction, polarized in a different direction from the first polarization portion 115, and positioned adjacent to the first polarization portion 115 on the X direction side. The refractive index differs between the position within the optical element 110 where the positive electrode 120 is provided and the position within the optical element 110 where the negative electrode 125 is provided. The change in refractive index within the optical element 110 generates a diffraction grating 117 having a pitch direction along the X direction within the optical element 110. Adding an easily fabricated long-period polarization reversal structure to the optical element 110 formed using a ferroelectric material reduces the drive voltage required to achieve the desired diffraction efficiency, enabling high-speed modulation of the processed light EL.

[0095] Additionally, positive and negative electrodes 120, 125 (first and second electrodes) are provided on the placement surface 113 of the optical element 110 at a location where the first polarization portion 115 is located. An electric field is generated in the first polarization portion 115, directed from the positive electrode 120 to the negative electrode 125. Positive and negative electrodes 120, 125 (third and fourth electrodes) are provided on the placement surface 113 of the optical element 110 at a location where the second polarization portion 116 is located. An electric field is generated in the second polarization portion 116, directed from the positive electrode 120 to the negative electrode 125. This allows for the generation of a diffraction grating 117 with a long period (grating pitch) without narrowing the period at which the electrodes are arranged. Therefore, the thickness (interaction length) of the diffraction grating can be increased while satisfying the Q parameter condition for obtaining a Raman-Nath diffraction grating. This allows for a lower drive voltage to obtain the desired diffraction efficiency, enabling high-speed modulation of the processed light EL.

[0096] Furthermore, the processing light EL incident on the optical element 110 passes through a region in the optical element 110 where the refractive index changes along a direction intersecting the X direction. At this time, the processing light EL incident on the incident surface 111 of the optical element 110 is totally reflected at the positions of the positive and negative electrodes 120, 125 on the arrangement surface 113 and is emitted from the emission surface 112. This facilitates interaction between the processing light EL and the electric field, making it possible to lower the drive voltage required to obtain the desired diffraction efficiency and modulate the processing light EL at high speed.

[0097] In the first embodiment described above, the processing light EL incident on the incident surface 111 of the optical element 110 is totally reflected at the positions of the positive and negative electrodes 120, 125 on the mounting surface 113, but this is not limited thereto. The optical element 110 may also include a slab waveguide configured so that the processing light EL incident on the incident surface 111 passes through a region of the optical element 110 where the refractive index changes. The slab waveguide allows the optical path of the processing light EL to continue close to the electrodes, allowing interaction between the processing light EL and the electric field to be achieved over a long distance. This allows the driving voltage required to achieve the desired diffraction efficiency to be reduced, enabling high-speed modulation of the processing light EL. In this case, as in the spatial light modulator 100A shown in FIG. 16 , the slab waveguide 119A may be configured so that the processing light EL incident on the incident surface 111 passes linearly parallel to the mounting surface 113. As in the spatial light modulation element 100B shown in Figure 17, the slab waveguide 119B may be configured so that the processing light EL incident from the incident surface 111 is totally reflected at the positions of the positive and negative electrodes 120, 125 on the placement surface 113 and passes through.

[0098] In the first embodiment described above, a Raman-Nath diffraction grating is generated in the spatial light modulation element 100, but this is not limiting, and a Bragg diffraction grating can also be generated.

[0099] Second Embodiment The spatial light modulation element applicable to the optical processing apparatuses 1, 51, and 61 described above is not limited to the spatial light modulation element 100 according to the first embodiment, but may also be any of the spatial light modulation elements according to the second to sixth embodiments. Next, a spatial light modulation element according to the second embodiment will be described. The spatial light modulation element according to the second embodiment is a line-type electro-optic spatial light modulation element having a configuration advantageous for Bragg diffraction. As shown in FIGS. 18 to 20 , the spatial light modulation element 200 according to the second embodiment includes an optical element 210, multiple positive electrodes 220, multiple negative electrodes 225, multiple positive wires 230, and multiple negative wires 235. The spatial light modulation element 200 modulates and emits sheet-shaped processing light EL having a cross-sectional shape shaped into a flattened ellipse.

[0100] In the second embodiment, the directions indicated by the arrows in FIG. 18 may be referred to as the X direction, the Y direction, and the Z direction, respectively. The X direction, the Y direction, and the Z direction are directions perpendicular to one another. The spatial light modulation element 200 according to the second embodiment is disposed so as to be tilted (rotated) around the Y axis by the Bragg angle with respect to the direction in which the processing light EL travels (the Z direction). The direction tilted by the Bragg angle with respect to the Z direction may be referred to as the Z1 direction, and the direction tilted by the Bragg angle with respect to the X direction may be referred to as the X1 direction. The X1 direction, the Y direction, and the Z1 direction are directions perpendicular to one another.

[0101] The optical element 210 is formed in the same manner as the optical element 110 according to the first embodiment. An incident surface 211 is formed at one end (in the -Z1 direction) of the optical element 110. A sheet-shaped (elliptical in cross section) processing light EL traveling in the Z direction is incident on the incident surface 211 as incident light. The Z direction may also be referred to as the first axis direction, and the incident surface 111 may intersect with the first axis. The Z1 direction may also be referred to as the direction along the first axis. An exit surface 212 is formed at the end (in the +Z1 direction) of the optical element 210 opposite the incident surface 211. Light entering the optical element 210 from the incident surface 211 is emitted from the exit surface 212.

[0102] An arrangement surface 213 on which positive and negative electrodes 220, 225 are arranged is formed on a side surface on the +Y direction side of the optical element 210. Multiple pairs of positive and negative electrodes 220, 225 are arranged along the X1 direction on the arrangement surface 213. The positive and negative electrodes 220, 225 are formed using a metal material containing, for example, gold (Au). A buffer layer 214 (see FIG. 21 ) is formed between the arrangement surface 213 and the multiple pairs of positive and negative electrodes 220, 225. The buffer layer 214 is formed using, for example, silicon dioxide (SiO2). The X1 direction may also be referred to as the second axis direction, and the Y direction may also be referred to as the third axis direction. The arrangement surface 213 may also intersect with the third axis.

[0103] The optical element 210 has a periodically poled structure similar to the optical element 110 according to the first embodiment. The optical element 210 includes a plurality of first polarized portions 215 extending in the Z1 direction and a plurality of second polarized portions 216 extending in the Z1 direction adjacent to the first polarized portions 215, arranged alternately along the X1 direction. For example, when three lenses 24 of the lens array 23 of the optical processing device are arranged side by side in the X direction, the optical element 210 may have at least nine first polarized portions 215 and at least eight second polarized portions 216. When five lenses 24 of the lens array 23 of the optical processing device are arranged side by side in the X direction, the optical element 210 may have at least fifteen first polarized portions 215 and at least fourteen second polarized portions 216. The second polarized portions 216 are polarized in a different direction (specifically, the opposite direction) from the first polarized portions 215. Similar to the optical element 110 according to the first embodiment, a periodic polarization inversion structure is provided in the optical element 210. The second polarization portion 216 located adjacent to the first polarization portion 215 on the −X1 direction side may be referred to as a third polarization portion.

[0104] A positive electrode 220 is provided on the arrangement surface 213 at a position spanning the first polarized portion 215 and the second polarized portion 216 (third polarized portion) located adjacent to the first polarized portion 215 on the −X1 direction side. The positive electrode 220 is formed extending in the Z1 direction from one end side to the other end side of the first polarized portion 215 (and the third polarized portion). A negative electrode 225 is provided on the arrangement surface 213 at a position spanning the first polarized portion 215 and the second polarized portion 216 located adjacent to the first polarized portion 215 on the +X1 direction side. The negative electrode 225 is formed extending in the Z1 direction parallel to the positive electrode 220 from one end side to the other end side of the first polarized portion 215 (and the second polarized portion 216). It can also be said that the positive electrode 220 is provided at a position on the arrangement surface 213 spanning the second polarized portion 216 and the first polarized portion 215 located adjacent to the second polarized portion 216 on the +X1 direction side (the opposite side to the negative electrode 225) of the second polarized portion 216. The positive electrode 220 spanning the second polarized portion 216 and the first polarized portion 215 located adjacent to the second polarized portion 216 on the +X1 direction side (the opposite side to the negative electrode 225) may be referred to as a third electrode.

[0105] The multiple positive electrodes 220 are individually electrically connected to multiple positive wires 230. The multiple positive wires 230 are electrically connected to the drive circuit 22 described above. The multiple positive wires 230 apply voltages supplied from the drive circuit 22 to the multiple positive electrodes 220 individually. By applying a voltage to the positive electrodes 220 via the positive wires 230, a potential difference can be created between adjacent positive and negative electrodes 220, 225. The multiple negative electrodes 225 are individually electrically connected to multiple ground wires 235. The multiple ground wires 235 are electrically connected to the drive circuit 22. The multiple positive wires 230 and the multiple ground wires 235 constitute the wiring EW described above.

[0106] 19 and 20 , in the spatial light modulation element 200 configured as described above, sheet-shaped (elliptical in cross section) processing light EL is incident as incident light on the incident surface 211 of the optical element 210. When no voltage is applied to the positive and negative electrodes 220, 225, the sheet-shaped processing light EL that enters the optical element 210 from the incident surface 211 is totally reflected at the positions of the positive and negative electrodes 220, 225 on the arrangement surface 213 and emerges from the emergence surface 212 as zero-order diffracted light.

[0107] As shown in Figure 21 , when a voltage (a voltage lower than the aforementioned polarization inversion voltage) is applied to the positive electrode 220 via the positive wire 230, a potential difference is generated between the adjacent positive and negative electrodes 220, 225, and an electric field is generated inside the optical element 210, directed from the positive electrode 220 to the negative electrode 225. As described above, the optical element 210 has a periodically polarization inversion structure. In Figure 21 , the polarization directions in the first polarization portion 215 and the second polarization portion 216 are schematically indicated by thick arrows. The graph shown in Figure 21 also shows changes in the refractive index in the first polarization portion 215 and the second polarization portion 216.

[0108] A voltage is applied to the positive electrode 220 that spans the first polarized portion 215 and the second polarized portion 216 (third polarized portion) located adjacent to the first polarized portion 215 on the −X1 direction side. This generates an electric field from the positive electrode 220 toward the first polarized portion 215 in the portion of the placement surface 213 where the first polarized portion 215 is located. The electric field gradually changes direction and moves toward the adjacent negative electrode 225 on the +X1 direction side. As the electric field moves from the positive electrode 220 toward the adjacent negative electrode 225 on the +X1 direction side, the refractive index within the first polarized portion 215 changes due to the electro-optic effect. The refractive index of the region inside the first polarized portion 215 near the placement surface 213 varies along the X1 direction, for example, becoming higher the closer to the positive electrode 220 and becoming lower the closer to the negative electrode 225.

[0109] A voltage is applied to the positive electrode 220 (third electrode) that spans the second polarized portion 216 and the first polarized portion 215 located adjacent to the second polarized portion 216 on the +X1 direction side. This generates an electric field from the positive electrode 220 toward the negative electrode 225 in the portion of the placement surface 213 where the second polarized portion 216 is located, and the electric field gradually changes direction toward the adjacent negative electrode 225 on the −X1 direction side. As the electric field moves from the positive electrode 220 toward the adjacent negative electrode 225 on the −X1 direction side, the refractive index within the second polarized portion 216 changes due to the electro-optic effect. The second polarized portion 216 is polarized in a different direction (specifically, the opposite direction) from the first polarized portion 215. Therefore, the refractive index of the region inside the second polarizing portion 216 near the placement surface 213 changes along the X1 direction, for example, so that the refractive index becomes lower at a position closer to the positive electrode 220 and becomes higher at a position closer to the negative electrode 225. A diffraction grating 217 having a pitch direction along the X1 direction is generated in the region inside the optical member 210 (the first polarizing portion 215 and the second polarizing portion 216) where the refractive index changes.

[0110] With a voltage applied to the positive electrode 220, the sheet-like processing light EL incident on the incident surface 211 and entering the optical element 210 is diffracted by Bragg diffraction in the region where the diffraction grating 217 is generated (i.e., the region where the refractive index is changed). The diffracted light DL (e.g., +1st-order diffracted light) generated by Bragg diffraction is totally reflected at the positions of the positive and negative electrodes 220, 225 on the arrangement surface 213 and emitted from the emission surface 212. In this way, the spatial light modulator 200 modulates the processing light EL incident on the incident surface 211 of the optical element 210 by the potential difference between the adjacent positive and negative electrodes 220, 225, and emits the diffracted light DL from the emission surface 212.

[0111] Here, a comparison will be made with the conventional spatial light modulation element 150 described in the first embodiment. As described above, in the conventional spatial light modulation element 150, if the distance between the positive and negative electrodes 170, 175 is 20 μm, the period Λ of the diffraction grating 167 is 40 μm.

[0112] The spatial light modulation element 200 according to the second embodiment has a periodic polarization inversion structure, and the refractive index changes in the same way in the first polarization portion 215 and the second polarization portion 216 due to the potential difference between the positive and negative electrodes 220, 225. Therefore, the spatial light modulation element 200 according to the second embodiment has a periodic polarization inversion structure with a period of 40 μm and a duty ratio of 1:1, and the distance between the positive and negative electrodes 220, 225 is maintained at 20 μm. In this case, the period Λ of the diffraction grating 217 is 20 μm. That is, the period of the diffraction grating 217 in the spatial light modulation element 200 according to the second embodiment is half the period of the diffraction grating 167 in the conventional spatial light modulation element 150. Note that a periodic polarization inversion structure with a period of 40 μm and a duty ratio of 1:1 is relatively long and therefore easy to fabricate. Here, the wavelength λ of the incident light (processing light) is 1 μm, and the refractive index n of the crystal (optical element 210) at the wavelength λ (λ = 1 μm) is 2.2. The thickness (interaction length) L of the diffraction grating 217 is 2.24 mm, the same as the thickness (interaction length) L of the diffraction grating 117 according to the first embodiment. In this case, in the spatial light modulation element 200 according to the second embodiment, Q is approximately 16 according to the above-described formula (1), and a Bragg diffraction type diffraction grating can be generated.

[0113] As can be seen from the above-mentioned equation (2), the diffraction efficiency is proportional to the square of the Bessel function of the diffraction grating thickness (interaction length) L. When a Bragg diffraction grating is generated in the spatial light modulation element 200 according to the second embodiment, the thickness (interaction length) L of the diffraction grating 217 can be made larger than 2.24 mm, thereby achieving the desired diffraction efficiency at a lower voltage than when using the conventional spatial light modulation element 150. Furthermore, since the desired diffraction efficiency can be achieved at a low voltage, the burden on the drive circuit is reduced and the processing light EL can be modulated at high speed. Furthermore, since the period of the diffraction grating 217 is shortened, the processing light EL can be modulated precisely.

[0114] As described in the first embodiment, in order to independently modulate a portion of the incident light, taking into account the divergence angle of the light source, it is necessary to collectively control the refractive index change of three periods or more in the diffraction grating, i.e., at least three pairs of positive and negative electrodes in the second embodiment. In the spatial light modulation element 200 according to the second embodiment, the multiple positive electrodes 220 are individually electrically connected to the drive circuit 22 via multiple positive wires 230. The multiple negative electrodes 225 are individually electrically connected to the drive circuit 22 via multiple ground wires 235. By using the drive circuit 22 to independently control the voltage of each control group consisting of at least three pairs of positive and negative electrodes 220, 225, it is possible to independently modulate a portion of the incident light (processing light EL).

[0115] For example, when three lenses 24 of the lens array 23 of the optical processing device are arranged side by side in the X direction, applying a voltage to the positive electrodes 220 of the first to third pairs of positive and negative electrodes 220, 225 counting from the bottom of the paper in Fig. 19 may independently modulate the light in the end 1 / 3 portion of the sheet-like processing light EL in the -X direction, and emit diffracted light DL from the emission surface 212. Applying a voltage to the positive electrodes 220 of the fourth to sixth pairs of positive and negative electrodes 220, 225 counting from the bottom of the paper in Fig. 19 may independently modulate the light in the central 1 / 3 portion of the sheet-like processing light EL, and emit diffracted light DL from the emission surface 212. By applying a voltage to the positive electrodes 220 of the 7th to 9th pairs of positive and negative electrodes 220, 225 counting from the bottom of the paper in Figure 19, the light in the 1 / 3 portion on the end side in the +X direction of the sheet-shaped processing light EL can be independently modulated, and diffracted light DL can be emitted from the emission surface 212.

[0116] The positive and negative electrodes 220, 225 are arranged side by side in the X1 direction, which is inclined by the Bragg angle with respect to the X direction in which the lenses 24 of the lens array 23 are arranged. When three lenses 24 of the lens array 23 are arranged side by side in the X direction, the lenses 24 located at the end in the -X direction may be arranged opposite the portion (exit surface 212) of the optical element 210 in which the first to third pairs of positive and negative electrodes 220, 225 are arranged. The lenses 24 located in the center may be arranged opposite the portion (exit surface 212) of the optical element 210 in which the fourth to sixth pairs of positive and negative electrodes 220, 225 are arranged. The lenses 24 located at the end in the +X direction may be arranged opposite the portion (exit surface 212) of the optical element 210 in which the seventh to ninth pairs of positive and negative electrodes 220, 225 are arranged.

[0117] [Characteristic Configuration of Second Embodiment] The spatial light modulation element 200 according to the second embodiment includes an optical element 210 formed using a light-transmitting ferroelectric material, on which processing light EL traveling along the Z direction (first axis) is incident as incident light, positive and negative electrodes 220, 225 arranged on a placement surface 213 of the optical element 210 along the X1 direction (second axis), and wiring (a positive line 230 and a ground line 235) that applies a voltage to the positive electrode 220 so as to create a potential difference between the positive and negative electrodes 220, 225. In other words, the spatial light modulation element 200 according to the second embodiment includes the optical element 210 and the positive and negative electrodes 220, 225, and when a potential difference is generated between the positive and negative electrodes 220, 225, the refractive index within the optical element 210 changes along the X direction.

[0118] This enables high-speed modulation of the processing light EL (incident light) by modulating the processing light EL using the potential difference between the positive and negative electrodes 220, 225. Furthermore, since the positive and negative electrodes 220, 225 are provided only on one side (the placement surface 213) of the optical element 210, the optical element 210 can be made thicker, and even when high-power laser light is used as the processing light EL, an increase in the optical power density within the optical element 210 can be suppressed. Since the positive and negative electrodes 220, 225 are provided only on one side of the optical element 210, there is no need to thin the optical element 210, install electrodes on both sides of the optical element 210, or bond a reinforcing member to thin the optical element 210, facilitating the manufacture of the spatial light modulator. The positive and negative electrodes 220, 225 may be arranged adjacent to each other along the X1 direction. The placement surface 213 of the optical element 210 may intersect with the Y axis (third axis).

[0119] The optical element 210 also includes a first polarization portion 215 extending along the Z1 direction and a second polarization portion 216 extending along the Z1 direction, polarized in a different direction from the first polarization portion 215, and positioned adjacent to the first polarization portion 215 on the X1 direction side. The refractive index differs between the position within the optical element 210 where the positive electrode 220 is provided and the position within the optical element 210 where the negative electrode 225 is provided. The change in refractive index within the optical element 210 generates a diffraction grating 217 having a pitch direction along the X direction within the optical element 210. Adding an easily fabricated long-period polarization reversal structure to the optical element 210, which is formed using a ferroelectric material, reduces the drive voltage required to achieve the desired diffraction efficiency, enabling high-speed modulation of the processed light EL.

[0120] A positive electrode 220 is provided on the arrangement surface 213 at a position spanning the first polarization portion 215 and the second polarization portion 216 (third polarization portion) located adjacent to the first polarization portion 215 on the −X1 direction side. A negative electrode 225 is provided on the arrangement surface 213 at a position spanning the first polarization portion 215 and the second polarization portion 216 located adjacent to the first polarization portion 215 on the +X1 direction side. An electric field is generated in the first polarization portion 215 from the positive electrode 220 to the negative electrode 225. A positive electrode 220 (third electrode portion) is provided on the arrangement surface 213 at a position opposite the negative electrode 225 of the second polarization portion 216. An electric field is generated in the second polarization portion 116 from the positive electrode 220 to the negative electrode 225. This makes it possible to generate a diffraction grating 217 with a short period (grating pitch). Therefore, since the thickness (interaction length) of the diffraction grating can be increased while satisfying the Q parameter condition for obtaining a Bragg diffraction grating, the drive voltage for obtaining a desired diffraction efficiency can be reduced, and the processing light EL can be modulated at high speed. In addition, since the period of the diffraction grating 217 is shortened, the processing light EL can be modulated precisely.

[0121] Furthermore, the processing light EL incident on the optical element 210 passes through a region in the optical element 210 where the refractive index changes along a direction intersecting the X1 direction. At this time, the processing light EL incident on the incident surface 211 of the optical element 210 is totally reflected at the positions of the positive and negative electrodes 220, 225 on the arrangement surface 213 and is emitted from the emission surface 212. This facilitates interaction between the processing light EL and the electric field, making it possible to lower the drive voltage required to obtain the desired diffraction efficiency and modulate the processing light EL at high speed.

[0122] In the second embodiment described above, similarly to the first embodiment, the optical element 210 may include a slab waveguide configured so that the processing light EL incident from the incident surface 211 passes through a region in the optical element 210 where the refractive index is changed. The slab waveguide allows the optical path of the processing light EL to continue close to the electrode, enabling interaction between the processing light EL and the electric field to be obtained over a long distance. This allows the drive voltage required to obtain a desired diffraction efficiency to be lowered, enabling high-speed modulation of the processing light EL.

[0123] In the second embodiment described above, a Bragg diffraction grating is generated in the spatial light modulation element 200, but this is not limiting, and it is also possible to generate a Raman-Nath diffraction grating.

[0124] Third Embodiment Next, a spatial light modulation element according to a third embodiment will be described. The spatial light modulation element according to the third embodiment is a line-type electro-optic spatial light modulation element that generates a Bragg diffraction grating. As shown in FIGS. 22 and 23 , the spatial light modulation element 300 according to the third embodiment includes an optical element 310, a plurality of positive electrodes 320A, 320B, and 320C, a plurality of negative electrodes 325A, 325B, and 325C, a plurality of positive wires (not shown), and a plurality of negative wires (not shown). The spatial light modulation element 300 modulates and emits a sheet-shaped processed light EL having a cross-sectional shape shaped into a flattened ellipse.

[0125] In the third embodiment, the directions indicated by the arrows in FIG. 22 may be referred to as the X direction, the Y direction, and the Z direction, respectively. The X direction, the Y direction, and the Z direction are perpendicular to one another. The spatial light modulation element 300 according to the third embodiment is disposed tilted (rotated) around the Y axis by the Bragg angle with respect to the direction in which the processing light EL travels (the Z direction). The direction tilted by the Bragg angle with respect to the Z direction may be referred to as the Z1 direction, and the direction tilted by the Bragg angle with respect to the X direction may be referred to as the X1 direction. The X1 direction, the Y direction, and the Z1 direction are perpendicular to one another.

[0126] The optical element 310 is formed in the same manner as the optical element 110 according to the first embodiment. An incident surface 311 is formed at one end (in the -Z1 direction) of the optical element 310. A sheet-like (elliptical in cross section) processing light EL traveling in the Z direction is incident on the incident surface 311 as incident light. The Z direction may also be referred to as the first axis direction, and the incident surface 311 may intersect with the first axis. The Z1 direction may also be referred to as the direction along the first axis. An exit surface 312 is formed at the end (in the +Z1 direction) of the optical element 310 opposite the incident surface 311. Light entering the optical element 310 from the incident surface 311 is emitted from the exit surface 312.

[0127] An arrangement surface 313 on which a plurality of positive electrodes 320A, 320B, and 320C and a plurality of negative electrodes 325A, 325B, and 325C are arranged is formed on a side surface on the +Y direction side of the optical member 310. The plurality of positive electrodes 320A, 320B, and 320C and the plurality of negative electrodes 325A, 325B, and 325C are formed using a metal material containing, for example, gold (Au). As in the first embodiment, a buffer layer 314 is formed between the arrangement surface 313 and the plurality of positive electrodes 320A, 320B, and 320C and the plurality of negative electrodes 325A, 325B, and 325C.

[0128] The optical member 310 has a periodic polarization reversal structure similar to the optical member 110 according to the first embodiment. The optical member 310 includes first polarization portions 315 extending in the Z1 direction and second polarization portions 316 adjacent to the first polarization portions 315 and extending in the Z1 direction, which are alternately arranged along the X1 direction. The second polarization portions 316 are polarized in a different direction (specifically, the opposite direction) from the first polarization portions 315. The X1 direction may be referred to as the second axis direction, and the Y direction may be referred to as the third axis direction. The placement surface 313 may intersect with the third axis.

[0129] In the first region 301A at the end side in the -Z1 direction of the placement surface 313, a pair of positive and negative electrodes 320A, 325A is provided in the portion where the first polarization portion 315 is located. The positive and negative electrodes 320A, 325A of the first region 301A are formed extending parallel to the Z1 direction from one end side to the other end side of the first region 301A in the portion where the first polarization portion 315 is located on the placement surface 313. The negative electrode 325A of the first region 301A is arranged adjacent to the positive electrode 320A of the first region 301A on the +X1 direction side. The positive and negative electrodes 320A, 325A of the first region 301A may be referred to as the first and second electrodes of the first region 301A in the portion of the placement surface 313 where the first polarization portion 315 is located.

[0130] Furthermore, a pair of positive and negative electrodes 320A, 325A are provided in the first region 301A in the placement surface 313, in a portion where the second polarization portion 316 is located. The positive and negative electrodes 320A, 325A of the first region 301A are formed in the portion of the placement surface 313 where the second polarization portion 316 is located, extending parallel to the Z1 direction from one end to the other end of the first region 301A. The negative electrode 325A of the first region 301A is arranged adjacent to the positive electrode 320A of the first region 301A on the +X1 direction side. The positive and negative electrodes 320A, 325A of the first region 301A may be referred to as the third and fourth electrodes of the first region 301A in the portion of the placement surface 313 where the second polarization portion 316 is located.

[0131] In a second region 301B (toward the center of the arrangement surface 313) adjacent to the first region 301A on the +Z1 direction side of the arrangement surface 313, pairs of positive and negative electrodes 320B, 325B are provided in the portions where the first polarization portions 315 are located. The positive and negative electrodes 320B, 325B of the second region 301B are formed to extend parallel to the Z1 direction from one end side to the other end side of the second region 301B in the portions where the first polarization portions 315 are located on the arrangement surface 313. The negative electrode 325B of the second region 301B is arranged adjacent to the positive electrode 320B of the second region 301B on the +X1 direction side. The positive and negative electrodes 320B, 325B of the second region 301B may be referred to as the first and second electrodes of the second region 301B in the portion of the placement surface 313 where the first polarized portion 315 is located.

[0132] Furthermore, in the second region 301B on the placement surface 313, a pair of positive and negative electrodes 320B, 325B is provided in a portion where the second polarization portion 316 is located. The positive and negative electrodes 320B, 325B of the second region 301B are formed in the portion where the second polarization portion 316 is located on the placement surface 313, extending parallel to the Z1 direction from one end side to the other end side of the second region 301B. The negative electrode 325B of the second region 301B is arranged adjacent to the positive electrode 320B of the second region 301B on the +X1 direction side. The positive and negative electrodes 320B, 325B of the second region 301B may be referred to as the third and fourth electrodes of the second region 301B in the portion where the second polarization portion 316 is located on the placement surface 313.

[0133] In a third region 301C adjacent to the second region 301B on the +Z1 direction side of the arrangement surface 313 (at the end side of the arrangement surface 313 in the +Z1 direction), a pair of positive and negative electrodes 320C, 325C is provided in each portion where the first polarization portion 315 is located. The positive and negative electrodes 320C, 325C of the third region 301C are formed to extend parallel to the Z1 direction from one end side to the other end side of the third region 301C in the portion of the arrangement surface 313 where the first polarization portion 315 is located. The negative electrode 325C of the third region 301C is arranged adjacent to the positive electrode 320C of the third region 301C on the +X1 direction side. The positive and negative electrodes 320C, 325C of the third region 301C may be referred to as the first and second electrodes of the third region 301C in the portion of the placement surface 313 where the first polarized portion 315 is located.

[0134] Furthermore, in the third region 301C on the placement surface 313, a pair of positive and negative electrodes 320C, 325C is provided in a portion where the second polarization portion 316 is located. The positive and negative electrodes 320C, 325C of the third region 301C are formed in the portion where the second polarization portion 316 is located on the placement surface 313, extending parallel to the Z1 direction from one end side to the other end side of the third region 301C. The negative electrode 325C of the third region 301C is arranged adjacent to the positive electrode 320C of the third region 301C on the +X1 direction side. The positive and negative electrodes 320C, 325C of the third region 301C may be referred to as the third and fourth electrodes of the third region 301C in the portion where the second polarization portion 316 is located on the placement surface 313.

[0135] The positive and negative electrodes 320A, 325A of the first region 301A, the positive and negative electrodes 320B, 325B of the second region 301B, and the positive and negative electrodes 320C, 325C of the third region 301C are provided separated from one another along the Z1 direction. As shown by hatching in Fig. 22 , the positive and negative electrodes 320A, 325A of the first region 301A in the first polarization portion 315, the positive and negative electrodes 320B, 325B of the second region 301B in the second polarization portion 316 adjacent to the first polarization portion 315 on the +X1 direction side, and the positive and negative electrodes 320C, 325C of the third region 301C in the other first polarization portion 315 adjacent to the second polarization portion 316 on the +X1 direction side are arranged side by side along the traveling direction of the diffracted light DL due to Bragg diffraction. The positive and negative electrodes 320A, 325A of the first region 301A in the second polarization portion 316, the positive and negative electrodes 320B, 325B of the second region 301B in the first polarization portion 315 adjacent to the +X1 direction side of the second polarization portion 316, and the positive and negative electrodes 320C, 325C of the third region 301C in the other second polarization portion 316 adjacent to the +X1 direction side of the first polarization portion 315 are arranged side by side along the direction of propagation of the diffracted light DL due to Bragg diffraction.

[0136] The multiple positive electrodes 320A, 320B, 320C are individually electrically connected to multiple positive wires (not shown). The multiple positive wires are electrically connected to the drive circuit 22 described above. The multiple positive wires apply voltages supplied from the drive circuit 22 to the multiple positive electrodes 320A, 320B, 320C individually. By applying voltages to the positive electrodes via the positive wires, a potential difference can be created between adjacent positive and negative electrodes. The multiple negative electrodes 325A, 325B, 325C are individually electrically connected to multiple ground wires (not shown). The multiple ground wires are electrically connected to the drive circuit 22. The multiple positive wires and multiple ground wires constitute the wiring EW described above.

[0137] 22 and 23 , in the spatial light modulation element 300 configured as described above, sheet-shaped (elliptical in cross section) processed light EL is incident as incident light on the incident surface 311 of the optical element 310. When no voltage is applied to the plurality of positive electrodes 320A, 320B, 320C and the plurality of negative electrodes 325A, 325B, 325C, the sheet-shaped processed light EL that enters the interior of the optical element 310 from the incident surface 311 is totally reflected at the arrangement surface 313 within the optical element 310 and emerges from the emergence surface 312 as zero-order diffracted light.

[0138] When a voltage (a voltage lower than the above-described polarization inversion voltage) is applied to the positive electrode 320A of the first region 301A via a positive line (not shown), an electric field is generated from the positive electrode 320A of the first region 301A toward the negative electrode 325A, and the refractive index in the first polarization portion 315 and the second polarization portion 316 located in the first region 301A changes due to the electro-optic effect, as in the first embodiment. In the third embodiment, a Bragg diffraction type first diffraction grating (not shown) having a pitch direction along the X1 direction is generated in the region where the refractive index changes inside the optical element 310 (the first polarization portion 315 and the second polarization portion 316) located in the first region 301A.

[0139] When a voltage (a voltage lower than the above-mentioned polarization inversion voltage) is applied to the positive electrode 320B of the second region 301B via a positive line (not shown), an electric field is generated from the positive electrode 320B of the second region 301B toward the negative electrode 325B, and the refractive index in the first polarization portion 315 and the second polarization portion 316 located in the second region 301B changes due to the electro-optic effect, In the third embodiment, a Bragg diffraction type second diffraction grating (not shown) having a pitch direction along the X1 direction is generated in the region where the refractive index changes inside the optical member 310 (the first polarization portion 315 and the second polarization portion 316) located in the second region 301B.

[0140] When a voltage (a voltage lower than the above-described polarization inversion voltage) is applied to the positive electrode 320C of the third region 301C via a positive line (not shown), an electric field is generated from the positive electrode 320C of the third region 301C toward the negative electrode 325C, and the refractive index in the first polarization portion 315 and the second polarization portion 316 located in the third region 301C changes due to the electro-optic effect. In the third embodiment, a Bragg diffraction type third diffraction grating (not shown) having a pitch direction along the X1 direction is generated in the region where the refractive index changes inside the optical element 310 (the first polarization portion 315 and the second polarization portion 316) located in the third region 301C.

[0141] With a voltage applied to the positive electrodes 320A, 320B, and 320C, the sheet-like processing light EL incident on the incident surface 311 and entering the interior of the optical element 310 is diffracted by Bragg diffraction in the regions where the first to third diffraction gratings are generated (i.e., the regions where the refractive index changes). The diffracted light DL (e.g., +1st-order diffracted light) generated by Bragg diffraction is totally reflected at the arrangement surface 313 inside the optical element 310 and emitted from the emission surface 312. In this way, the spatial light modulator 300 modulates the processing light EL incident on the incident surface 311 of the optical element 310 by the potential difference between the adjacent positive and negative electrodes, and emits the diffracted light DL from the emission surface 312.

[0142] As disclosed in the literature "Masahide Okazaki, Syuhei Yoshimoto, Takao Chichibu, and Toshiaki Suhara, "Electro-optic spatial light modulator using periodically-poled MgO:s-LiTaO3 waveguide," IEEE Photonics Technology Letters, vol. 27, no. 15, pp. 1646-1648, August 2015," it is desirable to rotate the electrodes in the direction in which light is diffracted in Bragg diffraction. In the third embodiment, the positive and negative electrodes 320A, 325A of the first region 301A in the first polarization portion 315, the positive and negative electrodes 320B, 325B of the second region 301B in the second polarization portion 316 adjacent to the +X1 direction side of the first polarization portion 315, and the positive and negative electrodes 320C, 325C of the third region 301C in another first polarization portion 315 adjacent to the +X1 direction side of the second polarization portion 316 are arranged side by side along the propagation direction of the diffracted light DL due to Bragg diffraction. The positive and negative electrodes 320A, 325A of the first region 301A in the second polarization portion 316, the positive and negative electrodes 320B, 325B of the second region 301B in the first polarization portion 315 adjacent to the second polarization portion 316 on the +X1 direction side, and the positive and negative electrodes 320C, 325C of the third region 301C in the other second polarization portion 316 adjacent to the first polarization portion 315 on the +X1 direction side are arranged side by side along the traveling direction of the diffracted light DL due to Bragg diffraction. This makes it possible to clearly identify the boundary of applied voltage when viewed from the traveling direction of the diffracted light DL due to Bragg diffraction.

[0143] As described in the first embodiment, to independently modulate a portion of the incident light, it is necessary to collectively control the refractive index change of three or more periods in the diffraction grating, i.e., at least six pairs of positive and negative electrodes in the third embodiment. In the spatial light modulation element 300 according to the third embodiment, the multiple positive electrodes 320A, 320B, and 320C are individually electrically connected to the drive circuit 22 via multiple positive lines (not shown). The multiple negative electrodes 325A, 325B, and 325C are individually electrically connected to the drive circuit 22 via multiple ground lines (not shown). The drive circuit 22 independently controls the voltage for each control group consisting of at least six pairs of combinations of positive and negative electrodes 320A, 325A in the first region 301A, positive and negative electrodes 320B, 325B in the second region 301B, and positive and negative electrodes 320C, 325C in the third region 301C, which are aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction, thereby independently modulating a portion of the incident light (processed light EL).

[0144] [Characteristic Configuration of the Third Embodiment] According to the third embodiment, it is possible to obtain the same effects as those of the first embodiment. Furthermore, in the spatial light modulation element 300 according to the third embodiment, a first region 301A on the placement surface 313 of the optical element 310 has a plurality of positive and negative electrodes 320A, 325A that generate a first diffraction grating arranged along the X1 direction (second axis). A second region 301B on the placement surface 313 of the optical element 310 has a plurality of positive and negative electrodes 320B, 325B that generate a second diffraction grating arranged along the X1 direction. A third region 301C on the placement surface 313 of the optical element 310 has a plurality of positive and negative electrodes 320C, 325C that generate a third diffraction grating arranged along the X1 direction.

[0145] The positive and negative electrodes 320A and 325A in the first region 301A, the positive and negative electrodes 320B and 325B in the second region 301B, and the positive and negative electrodes 320C and 325C in the third region 301C are arranged side by side along the direction of propagation of diffracted light DL due to Bragg diffraction. In such an arrangement (e.g., the arrangement shown by hatching in FIG. 22 ), the first diffraction grating generated by the positive and negative electrodes 320A and 325A in the first region 301A, the second diffraction grating generated by the positive and negative electrodes 320B and 325B in the second region 301B, and the third diffraction grating generated by the positive and negative electrodes 320C and 325C in the third region 301C have mutually different phases of refractive index change in the X1 direction. However, the phase of the refractive index change of the second diffraction grating and the third diffraction grating is equal to the phase of the refractive index change of the first diffraction grating in the direction perpendicular to the propagation direction of the diffracted light DL due to Bragg diffraction, which makes it possible to clearly define the boundary of applied voltage when viewed from the propagation direction of the diffracted light DL due to Bragg diffraction.

[0146] [Modification of Third Embodiment] In the third embodiment described above, the positive and negative electrodes 320A, 325A in the first region 301A, the positive and negative electrodes 320B, 325B in the second region 301B, and the positive and negative electrodes 320C, 325C in the third region 301C are arranged separately from each other along the Z1 direction, but this is not limited to this. For example, as in the spatial light modulation element 350 shown in Figure 24, the positive and negative electrodes 370A, 375A in the first region 301A, the positive and negative electrodes 370B, 375B in the second region 301B, and the positive and negative electrodes 370C, 375C in the third region 301C, which are aligned along the propagation direction of diffracted light DL due to Bragg diffraction, may be formed so that electrodes located at the same positions in the X1 direction are connected to each other.

[0147] 24, the second pair of positive and negative electrodes, counting in the X1 direction, may be formed by connecting the positive and negative electrodes 370A, 375A in the first region 301A to the positive and negative electrodes 370B, 375B in the second region 301B. The third to sixth pairs of positive and negative electrodes, counting in the X1 direction, may be formed by connecting the positive and negative electrodes 370A, 375A in the first region 301A to the positive and negative electrodes 370B, 375B in the second region 301B to the positive and negative electrodes 370C, 375C in the third region 301C. In the seventh pair of positive and negative electrodes counting in the X1 direction, the positive and negative electrodes 370B, 375B in the second region 301B and the positive and negative electrodes 370C, 375C in the third region 301C may be formed so as to be connected to each other.

[0148] In the third embodiment described above, similarly to the first embodiment, the optical element 310 may include a slab waveguide configured so that the processing light EL incident on the incident surface 311 passes through a region of the optical element 310 where the refractive index is changed. The slab waveguide allows the optical path of the processing light EL to continue close to the electrode, enabling interaction between the processing light EL and the electric field to be obtained over a long distance. This allows the drive voltage required to obtain the desired diffraction efficiency to be lowered, enabling high-speed modulation of the processing light EL.

[0149] [Fourth Embodiment] Next, a spatial light modulation element according to a fourth embodiment will be described. The spatial light modulation element according to the fourth embodiment is a line-type electro-optic spatial light modulation element that generates a Bragg diffraction grating. As shown in FIGS. 25 and 26 , the spatial light modulation element 400 according to the fourth embodiment includes an optical element 410, a plurality of positive electrodes 420A-420E, a plurality of negative electrodes 425A-425E, a plurality of positive wires (not shown), and a plurality of negative wires (not shown). The spatial light modulation element 400 modulates and emits sheet-shaped processing light EL whose cross section is shaped into a flattened ellipse.

[0150] In the fourth embodiment, the directions indicated by the arrows in FIG. 25 may be referred to as the X direction, the Y direction, and the Z direction, respectively. The X direction, the Y direction, and the Z direction are perpendicular to one another. The spatial light modulation element 400 according to the fourth embodiment is disposed tilted (rotated) around the Y axis by the Bragg angle with respect to the direction in which the processing light EL travels (the Z direction). The direction tilted by the Bragg angle with respect to the Z direction may be referred to as the Z1 direction, and the direction tilted by the Bragg angle with respect to the X direction may be referred to as the X1 direction. The X1 direction, the Y direction, and the Z1 direction are perpendicular to one another.

[0151] The optical element 410 is formed in the same manner as the optical element 210 according to the second embodiment. An incident surface 411 is formed at one end (in the -Z1 direction) of the optical element 410. A sheet-shaped (elliptical in cross section) processing light EL traveling in the Z direction is incident on the incident surface 411 as incident light. The Z direction may also be referred to as the first axis direction, and the incident surface 411 may intersect with the first axis. The Z1 direction may also be referred to as the direction along the first axis. An exit surface 412 is formed at the end (in the +Z1 direction) of the optical element 410 opposite the incident surface 411. Light entering the optical element 410 from the incident surface 411 is emitted from the exit surface 412.

[0152] An arrangement surface 413 on which a plurality of positive electrodes 420A-420E and a plurality of negative electrodes 425A-425E are arranged is formed on a side surface on the +Y direction side of the optical member 410. The plurality of positive electrodes 420A-420E and the plurality of negative electrodes 425A-425E are formed using a metal material containing, for example, gold (Au). As in the second embodiment, a buffer layer 414 is formed between the arrangement surface 413 and the plurality of positive electrodes 420A-420E and the plurality of negative electrodes 425A-425E.

[0153] The optical member 410 has a periodic polarization reversal structure similar to the optical member 210 according to the second embodiment. The optical member 410 includes a plurality of first polarization portions 415 extending in the Z1 direction and second polarization portions 416 adjacent to the first polarization portions 415 and extending in the Z1 direction, arranged alternately along the X1 direction. The second polarization portions 416 are polarized in a different direction (specifically, the opposite direction) from the first polarization portions 415. The X1 direction may be referred to as the second axis direction, and the Y direction may be referred to as the third axis direction. The placement surface 413 may intersect with the third axis.

[0154] In the first region 401A at the end side in the -Z1 direction of the placement surface 413, a positive electrode 420A is provided at a position straddling the first polarization portion 415 and the second polarization portion 416 (third polarization portion) located adjacent to the first polarization portion 415 on the -X1 direction side. The positive electrode 420A in the first region 401A is formed extending in the Z1 direction from one end side to the other end side of the first region 401A at a position straddling the first polarization portion 415 and the second polarization portion 416 (third polarization portion). In the first region 401A, a negative electrode 425A is provided at a position straddling the first polarization portion 415 and the second polarization portion 416 located adjacent to the first polarization portion 415 on the +X1 direction side. The negative electrode 425A of the first region 401A is formed to extend in the Z1 direction parallel to the positive electrode 420A from one end to the other end of the first region 401A at a position straddling the first polarization portion 415 and the second polarization portion 416. It can also be said that the positive electrode 420A is provided in the first region 401A at a position straddling the second polarization portion 416 and the first polarization portion 415 located adjacent to the second polarization portion 416 on the +X1 direction side (the opposite side to the negative electrode 425A). The positive electrode 420A straddling the second polarization portion 416 and the first polarization portion 415 located adjacent to the second polarization portion 416 on the +X1 direction side (the opposite side to the negative electrode 425A) may be referred to as a third electrode.

[0155] In a second region 401B adjacent to the first region 401A on the placement surface 413 on the +Z1 direction side, positive and negative electrodes 420B, 425B of the second region 401B are provided similarly to the positive and negative electrodes 420A, 425A of the first region 401A. In a third region 401C adjacent to the second region 401B on the placement surface 413 on the +Z1 direction side, positive and negative electrodes 420C, 425C of the third region 401C are provided similarly to the positive and negative electrodes 420A, 425A of the first region 401A. In a fourth region 401D adjacent to the third region 401C on the placement surface 413 on the +Z1 direction side, positive and negative electrodes 420D, 425D of the fourth region 401D are provided similarly to the positive and negative electrodes 420A, 425A of the first region 401A. In the fifth region 401E adjacent to the +Z1 direction side of the fourth region 401D on the placement surface 413 (on the end side of the placement surface 413 in the +Z1 direction), positive and negative electrodes 420E, 425E of the fifth region 401E are provided, similar to the positive and negative electrodes 420A, 425A of the first region 401A.

[0156] The positive and negative electrodes 420A, 425A in the first region 401A, the positive and negative electrodes 420B, 425B in the second region 401B, the positive and negative electrodes 420C, 425C in the third region 401C, the positive and negative electrodes 420D, 425D in the fourth region 401D, and the positive and negative electrodes 420E, 425E in the fifth region 401E are arranged separated from each other along the Z1 direction. 25, the positive and negative electrodes 420A, 425A of the first region 401A in the first polarized portion 415, the positive and negative electrodes 420B, 425B of the second region 401B in the first polarized portion 415 arranged on the +X1 direction side of the first polarized portion 415 (through the second polarized portion 416), and the positive and negative electrodes 420B, 425B of the third region 401C in the first polarized portion 415 arranged on the +X1 direction side of the first polarized portion 415 (through the second polarized portion 416) The electrodes 420C, 425C, the positive and negative electrodes 420D, 425D of the fourth region 401D in the first polarization section 415 aligned on the +X1 direction side of the first polarization section 415 (via the second polarization section 416), and the positive and negative electrodes 420E, 425E of the fifth region 501E in the first polarization section 415 aligned on the +X1 direction side of the first polarization section 415 (via the second polarization section 416) are arranged side by side along the propagation direction of the diffracted light DL due to Bragg diffraction.

[0157] The multiple positive electrodes 420A to 420E are individually electrically connected to multiple positive wires (not shown). The multiple positive wires are electrically connected to the drive circuit 22 described above. The multiple positive wires apply voltages supplied from the drive circuit 22 to the multiple positive electrodes 420A to 420E individually. By applying voltages to the positive electrodes via the positive wires, a potential difference can be created between adjacent positive and negative electrodes. The multiple negative electrodes 425A to 425E are individually electrically connected to multiple ground wires (not shown). The multiple ground wires are electrically connected to the drive circuit 22. The multiple positive wires and multiple ground wires constitute the wiring EW described above.

[0158] 25 and 26, in the spatial light modulation element 400 configured as described above, sheet-shaped (elliptical in cross section) processing light EL is incident as incident light on the incident surface 411 of the optical element 410. When no voltage is applied to the plurality of positive electrodes 420A-420E and the plurality of negative electrodes 425A-425E, the sheet-shaped processing light EL that enters the interior of the optical element 410 from the incident surface 411 is totally reflected at the arrangement surface 413 within the optical element 410 and emerges from the emergence surface 412 as zero-order diffracted light.

[0159] When a voltage (a voltage lower than the above-described polarization inversion voltage) is applied to the positive electrode 420A of the first region 401A via a positive line (not shown), an electric field is generated from the positive electrode 420A of the first region 401A toward the negative electrode 425A, and the refractive index in the first polarization portion 415 and the second polarization portion 416 located in the first region 401A changes due to the electro-optic effect, as in the second embodiment. In the fourth embodiment, a Bragg diffraction type first diffraction grating (not shown) having a pitch direction along the X1 direction is generated in the region where the refractive index changes inside the optical element 410 (the first polarization portion 415 and the second polarization portion 416) located in the first region 401A.

[0160] When a voltage (a voltage lower than the above-mentioned polarization inversion voltage) is applied to the positive electrode 420B of the second region 401B via a positive line (not shown), an electric field is generated from the positive electrode 420B of the second region 401B toward the negative electrode 425B, and the refractive index in the first polarization portion 415 and the second polarization portion 416 located in the second region 401B changes due to the electro-optic effect, In the fourth embodiment, a Bragg diffraction type second diffraction grating (not shown) having a pitch direction along the X1 direction is generated in the region where the refractive index changes inside the optical element 410 (the first polarization portion 415 and the second polarization portion 416) located in the second region 401B.

[0161] When a voltage (a voltage lower than the above-described polarization inversion voltage) is applied to the positive electrode 420C of the third region 401C via a positive line (not shown), an electric field is generated from the positive electrode 420C of the third region 401C toward the negative electrode 425C, and the refractive index in the first polarization portion 415 and the second polarization portion 416 located in the third region 401C changes due to the electro-optic effect, In the fourth embodiment, a Bragg diffraction type third diffraction grating (not shown) having a pitch direction along the X1 direction is generated in the region where the refractive index changes inside the optical element 410 (the first polarization portion 415 and the second polarization portion 416) located in the third region 401C.

[0162] When a voltage (a voltage lower than the above-mentioned polarization inversion voltage) is applied to the positive electrode 420D of the fourth region 401D via a positive line (not shown), an electric field is generated from the positive electrode 420D of the fourth region 401D toward the negative electrode 425D, as in the second embodiment, and the refractive index in the first polarization portion 415 and the second polarization portion 416 located in the fourth region 401D changes due to the electro-optic effect. In the fourth embodiment, a Bragg diffraction type fourth diffraction grating (not shown) having a pitch direction along the X1 direction is generated in the region where the refractive index changes inside the optical element 410 (the first polarization portion 415 and the second polarization portion 416) located in the fourth region 401D.

[0163] When a voltage (a voltage lower than the above-described polarization inversion voltage) is applied to the positive electrode 420E of the fifth region 401E via a positive line (not shown), an electric field is generated from the positive electrode 420E of the fifth region 401E toward the negative electrode 425E, and the refractive index in the first polarization portion 415 and the second polarization portion 416 located in the fifth region 401E changes due to the electro-optic effect. In the fourth embodiment, a Bragg diffraction type fifth diffraction grating (not shown) having a pitch direction along the X1 direction is generated in the region where the refractive index changes inside the optical element 410 (the first polarization portion 415 and the second polarization portion 416) located in the fifth region 401E.

[0164] With a voltage applied to the positive electrodes 420A-420E, the sheet-like processing light EL incident on the incident surface 411 and entering the interior of the optical element 410 is diffracted by Bragg diffraction in the regions where the first to fifth diffraction gratings are generated (i.e., the regions where the refractive index changes). The diffracted light DL (e.g., +1st-order diffracted light) generated by Bragg diffraction is totally reflected at the arrangement surface 413 inside the optical element 410 and emitted from the emission surface 412. In this way, the spatial light modulator 400 modulates the processing light EL incident on the incident surface 411 of the optical element 410 by the potential difference between the adjacent positive and negative electrodes, and emits the diffracted light DL from the emission surface 412.

[0165] As described in the third embodiment, in the Bragg diffraction, it is desirable to rotate the electrodes in the direction in which light is diffracted. In the fourth embodiment, the positive and negative electrodes 420A, 425A of the first region 401A in the first polarized portion 415, the positive and negative electrodes 420B, 425B of the second region 401B in the first polarized portion 415 arranged on the +X1 direction side of the first polarized portion 415 (through the second polarized portion 416), and the positive and negative electrodes 420C, 425D of the third region 401C in the first polarized portion 415 arranged on the +X1 direction side of the first polarized portion 415 (through the second polarized portion 416) are arranged. 20C, 425C, the positive and negative electrodes 420D, 425D of the fourth region 401D in the first polarization portion 415 aligned on the +X1 direction side of the first polarization portion 415 (via the second polarization portion 416), and the positive and negative electrodes 420E, 425E of the fifth region 501E in the first polarization portion 415 aligned on the +X1 direction side of the first polarization portion 415 (via the second polarization portion 416) are arranged aligned along the traveling direction of the diffracted light DL due to Bragg diffraction. This makes it possible to clarify the boundary of applied voltage when viewed from the traveling direction of the diffracted light DL due to Bragg diffraction.

[0166] As described in the first embodiment, to independently modulate a portion of the incident light, it is necessary to collectively control the refractive index change of three or more periods in the diffraction grating, that is, at least three pairs of positive and negative electrodes in the fourth embodiment. In the spatial light modulation element 400 according to the fourth embodiment, the multiple positive electrodes 420A-420E are individually electrically connected to the drive circuit 22 via multiple positive lines (not shown). The multiple negative electrodes 425A-425E are individually electrically connected to the drive circuit 22 via multiple ground lines (not shown). The drive circuit 22 independently controls the voltage for each control group consisting of at least three pairs of combinations of positive and negative electrodes 420A, 425A in the first region 401A, a pair of positive and negative electrodes 420B, 425B in the second region 401B, a pair of positive and negative electrodes 420C, 425C in the third region 401C, a pair of positive and negative electrodes 420D, 425D in the fourth region 401D, and a pair of positive and negative electrodes 420E, 425E in the fifth region 401E, which are aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction, thereby independently modulating a portion of the incident light (processed light EL).

[0167] [Characteristic Configuration of Fourth Embodiment] According to the fourth embodiment, the same effects as those of the second embodiment can be obtained. Furthermore, in the spatial light modulation element 400 according to the fourth embodiment, a first region 401A on the mounting surface 413 of the optical element 410 is provided with a plurality of positive and negative electrodes 420A, 425A that generate a first diffraction grating, arranged along the X1 direction (second axis). A second region 401B on the mounting surface 413 of the optical element 410 is provided with a plurality of positive and negative electrodes 420B, 425B that generate a second diffraction grating, arranged along the X1 direction. A third region 401C on the mounting surface 413 of the optical element 410 is provided with a plurality of positive and negative electrodes 420C, 425C that generate a third diffraction grating, arranged along the X1 direction. A fourth region 401D on the mounting surface 413 of the optical element 410 is provided with a plurality of positive and negative electrodes 420D, 425D that generate a fourth diffraction grating, arranged along the X1 direction. In a fifth region 401E on the placement surface 413 of the optical member 410, a plurality of positive and negative electrodes 420E and 425E that generate a fifth diffraction grating are provided along the X1 direction.

[0168] The positive and negative electrodes 420A, 425A in the first region 401A, the positive and negative electrodes 420B, 425B in the second region 401B, the positive and negative electrodes 420C, 425C in the third region 401C, the positive and negative electrodes 420D, 425D in the fourth region 401D, and the positive and negative electrodes 420E, 425E in the fifth region 401E are arranged side by side along the direction of propagation of the diffracted light DL due to Bragg diffraction. In such an arrangement (for example, the arrangement shown by hatching in FIG. 25 ), the first diffraction grating generated by the positive and negative electrodes 320A, 325A in the first region 301A, the second diffraction grating generated by the positive and negative electrodes 320B, 325B in the second region 301B, the third diffraction grating generated by the positive and negative electrodes 320C, 325C in the third region 301C, the fourth diffraction grating generated by the positive and negative electrodes 420D, 425D in the fourth region 401D, and the fifth diffraction grating generated by the positive and negative electrodes 420E, 425E in the fifth region 401E have mutually different phases of refractive index change in the X1 direction. However, the phases of the refractive index change of the second to fifth diffraction gratings are equal to the phase of the refractive index change of the first diffraction grating in a direction perpendicular to the propagation direction of the diffracted light DL due to Bragg diffraction. This makes it possible to clearly define the boundary of the applied voltage when viewed from the direction in which the diffracted light DL due to Bragg diffraction travels.

[0169] [Variation of the Fourth Embodiment] In the above-described fourth embodiment, the positive and negative electrodes 420A, 425A in the first region 401A, the positive and negative electrodes 420B, 425B in the second region 401B, the positive and negative electrodes 420C, 425C in the third region 401C, the positive and negative electrodes 420D, 425D in the fourth region 401D, and the positive and negative electrodes 420E, 425E in the fifth region 401E are arranged separated from each other along the Z1 direction, but this is not limited to this. For example, as in the spatial light modulation element 450 shown in Figure 27, the positive and negative electrodes 470A, 475A in the first region 401A, the positive and negative electrodes 470B, 475B in the second region 401B, the positive and negative electrodes 470C, 475C in the third region 401C, the positive and negative electrodes 470D, 475D in the fourth region 401D, and the positive and negative electrodes 470E, 475E in the fifth region 401E, which are aligned along the direction of propagation of diffracted light DL due to Bragg diffraction, may be formed by connecting electrodes that are positioned in the same direction in the X1 direction.

[0170] 27, the second pair of positive and negative electrodes, counting in the X1 direction, may be formed by connecting the positive and negative electrodes 470A, 475A in the first region 401A to the positive and negative electrodes 470B, 475B in the second region 401B. The third pair of positive and negative electrodes, counting in the X1 direction, may be formed by connecting the positive and negative electrodes 470A, 475A in the first region 401A to the positive and negative electrodes 470B, 475B in the second region 401B to the positive and negative electrodes 470C, 475C in the third region 401C. In the fourth pair of positive and negative electrodes counting in the X1 direction, the positive and negative electrodes 470B, 475B in the second region 401B, the positive and negative electrodes 470C, 475C in the third region 401C, and the positive and negative electrodes 470D, 475D in the fourth region 401D may be connected to each other. In the fifth pair of positive and negative electrodes counting in the X1 direction, the positive and negative electrodes 470C, 475C in the third region 401C, the positive and negative electrodes 470D, 475D in the fourth region 401D, and the positive and negative electrodes 470E, 475E in the fifth region 401E may be connected to each other. In the sixth pair of positive and negative electrodes counting in the X1 direction, the positive and negative electrodes 470D, 475D in the fourth region 401D and the positive and negative electrodes 470E, 475E in the fifth region 401E may be formed so as to be connected to each other.

[0171] In the fourth embodiment, as in the first embodiment, the optical element 410 may include a slab waveguide configured so that the processing light EL incident on the incident surface 411 passes through a region of the optical element 410 where the refractive index is changed. The slab waveguide allows the optical path of the processing light EL to continue close to the electrode, allowing interaction between the processing light EL and the electric field to be obtained over a long distance. This allows the drive voltage required to obtain a desired diffraction efficiency to be lowered, enabling high-speed modulation of the processing light EL.

[0172] Fifth Embodiment Next, a spatial light modulation element according to a fifth embodiment will be described. The spatial light modulation element according to the fifth embodiment shares essential components with the spatial light modulation element 300 according to the third embodiment, except for the inclusion of a positive connection and a negative connection. Therefore, components similar to those of the third embodiment are denoted by the same reference numerals as in the third embodiment, and detailed descriptions thereof will be omitted. As shown in FIG. 28 , the spatial light modulation element 500 according to the fifth embodiment includes an optical element 310, a plurality of positive electrodes 320A, 320B, and 320C, a plurality of negative electrodes 325A, 325B, and 325C, a plurality of positive wires (not shown), a plurality of negative wires (not shown), first and second positive wires 540A and 540B, and first and second negative wires 545A and 545B. The spatial light modulation element 500 modulates and emits a sheet-shaped processed light EL having a cross-sectional shape shaped like a flattened ellipse.

[0173] The first positive side connection 540A electrically connects the positive electrode 320A in the first region 301A to the positive electrode 320B in the second region 301B, which are aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction. The second positive side connection 540B electrically connects the positive electrode 320B in the second region 301B to the positive electrode 320C in the third region 301C, which are aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction. As a result, the positive electrode 320A in the first region 301A, the positive electrode 320B in the second region 301B, and the positive electrode 320C in the third region 301C, which are aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction, are electrically connected by the first and second positive side connections 540A and 540B.

[0174] The first negative side connection 545A electrically connects the negative electrode 325A in the first region 301A to the negative electrode 325B in the second region 301B, which are aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction. The second negative side connection 545B electrically connects the negative electrode 325B in the second region 301B to the negative electrode 325C in the third region 301C, which are aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction. As a result, the negative electrode 325A in the first region 301A, the negative electrode 325B in the second region 301B, and the negative electrode 325C in the third region 301C, which are aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction, are electrically connected by the first and second negative side connections 545A and 545B.

[0175] A plurality of sets of positive electrodes 320A in the first region 301A, positive electrodes 320B in the second region 301B, and positive electrodes 320C in the third region 301C are arranged side by side along the direction of propagation of diffracted light DL due to Bragg diffraction and are electrically connected to a plurality of positive wires (not shown). The plurality of positive wires are electrically connected to the aforementioned drive circuit 22. The plurality of positive wires individually apply voltages supplied from the drive circuit 22 to the plurality of sets of positive electrodes 320A, 320B, and 320C arranged side by side along the direction of propagation of diffracted light DL due to Bragg diffraction. By applying a voltage to the positive electrodes via the positive wires, a potential difference can be created between adjacent positive and negative electrodes. A plurality of sets of negative electrodes 325A in the first region 301A, negative electrodes 325B in the second region 301B, and negative electrodes 325C in the third region 301C are arranged side by side along the direction of propagation of diffracted light DL due to Bragg diffraction, and are electrically connected to a plurality of ground lines (not shown). The plurality of ground lines are electrically connected to the drive circuit 22. The plurality of positive lines and the plurality of ground lines constitute the wiring EW described above.

[0176] In the spatial light modulation element 500 configured as described above, as in the third embodiment, sheet-shaped (elliptical in cross section) processing light EL is incident as incident light on the incident surface 311 of the optical element 310. When no voltage is applied to the plurality of positive electrodes 320A, 320B, 320C and the plurality of negative electrodes 325A, 325B, 325C, the sheet-shaped processing light EL that enters the interior of the optical element 310 from the incident surface 311 is totally reflected at the arrangement surface 313 within the optical element 310 and emerges from the emergence surface 312 as zero-order diffracted light.

[0177] When a voltage (a voltage lower than the above-described polarization inversion voltage) is applied to multiple sets of positive electrodes 320A, 320B, and 320C arranged along the traveling direction of diffracted light DL due to Bragg diffraction via multiple positive lines (not shown), a first Bragg diffraction grating (not shown) having a pitch direction along the X1 direction is generated in a region where the refractive index changes inside the optical element 310 (first polarization portions 315 and second polarization portions 316) located in the first region 301A, as in the third embodiment.A second Bragg diffraction grating (not shown) having a pitch direction along the X1 direction is generated in a region where the refractive index changes inside the optical element 310 (first polarization portions 315 and second polarization portions 316) located in the second region 301B. A third diffraction grating (not shown) of the Bragg diffraction type having a pitch direction along the X1 direction is generated in the region where the refractive index changes inside the optical element 310 (the first polarization portion 315 and the second polarization portion 316) located in the third region 301C.

[0178] With voltages applied to the multiple pairs of positive electrodes 320A, 320B, and 320C, the sheet-like processing light EL incident on the incident surface 311 and entering the interior of the optical element 310 is diffracted by Bragg diffraction in the regions where the first to third diffraction gratings are generated (i.e., the regions where the refractive index changes). The diffracted light DL (e.g., +1st-order diffracted light) resulting from the Bragg diffraction is totally reflected at the arrangement surface 313 within the optical element 310 and emitted from the emission surface 312. In this way, the spatial light modulator 500 modulates the processing light EL incident on the incident surface 311 of the optical element 310 by the potential difference between the adjacent positive and negative electrodes, and emits the diffracted light DL from the emission surface 312.

[0179] [Characteristic Configuration of Fifth Embodiment] According to the fifth embodiment, the same effects as those of the third embodiment can be obtained. Furthermore, in the spatial light modulation element 500 according to the fifth embodiment, the positive electrode 320A in the first region 301A, the positive electrode 320B in the second region 301B, and the positive electrode 320C in the third region 301C, which are aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction, are electrically connected by first and second positive side connections 540A and 540B. The negative electrode 325A in the first region 301A, the negative electrode 325B in the second region 301B, and the negative electrode 325C in the third region 301C, which are aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction, are electrically connected by first and second negative side connections 545A and 545B. This makes it possible to clearly identify the boundaries of applied voltages when viewed from the direction of propagation of the diffracted light DL due to Bragg diffraction. Furthermore, as shown by the hatching in Figure 28, by applying a voltage to at least six pairs of positive electrodes 320A, 320B, 320C arranged along the direction of propagation of the diffracted light DL due to Bragg diffraction, it is possible to independently modulate a portion of the incident light (processing light EL).

[0180] In the above-described fifth embodiment, as in the third embodiment, the optical element 310 may be provided with a slab waveguide configured so that the processing light EL incident from the incident surface 311 passes through a region within the optical element 310 where the refractive index is changed.

[0181] Sixth Embodiment Next, a spatial light modulation element according to the sixth embodiment will be described. The spatial light modulation element according to the sixth embodiment shares essential components with the spatial light modulation element 400 according to the fourth embodiment, except for the additional provision of a positive connection and a negative connection. Therefore, components similar to those of the fourth embodiment are denoted by the same reference numerals as in the fourth embodiment, and detailed descriptions thereof will be omitted. As shown in FIG. 29 , the spatial light modulation element 600 according to the sixth embodiment includes an optical element 410, a plurality of positive electrodes 420A-420E, a plurality of negative electrodes 425A-425E, a plurality of positive wires (not shown), a plurality of negative wires (not shown), first to fourth positive wire connections 640A-640D, and first to fourth negative wire connections 645A-645D. The spatial light modulation element 600 modulates and emits a sheet-shaped processing light EL having a cross-sectional shape shaped into a flattened ellipse.

[0182] The first positive side connection 640A electrically connects the positive electrode 420A in the first region 401A to the positive electrode 420B in the second region 401B, which are aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction. The second positive side connection 640B electrically connects the positive electrode 420B in the second region 401B to the positive electrode 420C in the third region 401C, which are aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction. The third positive side connection 640C electrically connects the positive electrode 420C in the third region 401C to the positive electrode 420D in the fourth region 401D, which are aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction. The fourth positive side connection 640D electrically connects the positive electrode 420D in the fourth region 401D and the positive electrode 420E in the fifth region 401E, which are aligned along the traveling direction of the diffracted light DL due to Bragg diffraction. As a result, the positive electrode 420A in the first region 401A, the positive electrode 420B in the second region 401B, the positive electrode 420C in the third region 401C, the positive electrode 420D in the fourth region 401D, and the positive electrode 420E in the fifth region 401C, which are aligned along the traveling direction of the diffracted light DL due to Bragg diffraction, are electrically connected by the first to fourth positive side connections 640A to 640D.

[0183] The first negative side connection 645A electrically connects the negative electrode 425A in the first region 401A to the negative electrode 425B in the second region 401B, which are aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction. The second negative side connection 645B electrically connects the negative electrode 425B in the second region 401B to the negative electrode 425C in the third region 401C, which are aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction. The third negative side connection 645C electrically connects the negative electrode 425C in the third region 401C to the negative electrode 425D in the fourth region 401D, which are aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction. The fourth negative side connection 645D electrically connects the negative electrode 425D in the fourth region 401D and the negative electrode 425E in the fifth region 401E, which are aligned along the traveling direction of the diffracted light DL due to Bragg diffraction. As a result, the negative electrode 425A in the first region 401A, the negative electrode 425B in the second region 401B, the negative electrode 425C in the third region 401C, the negative electrode 425E in the fourth region 401E, and the negative electrode 425E in the fifth region 401E, which are aligned along the traveling direction of the diffracted light DL due to Bragg diffraction, are electrically connected by the first to fourth negative side connections 645A to 645D.

[0184] A plurality of sets of positive electrodes 420A in the first region 401A, positive electrodes 420B in the second region 401B, positive electrodes 420C in the third region 401C, positive electrodes 420D in the fourth region 401D, and positive electrodes 420E in the fifth region 401C are arranged in a line along the direction of propagation of the diffracted light DL due to Bragg diffraction and are electrically connected to a plurality of positive wires (not shown). The plurality of positive wires are electrically connected to the aforementioned drive circuit 22. The plurality of positive wires individually apply voltages supplied from the drive circuit 22 to the plurality of sets of positive electrodes 420A-420E arranged in a line along the direction of propagation of the diffracted light DL due to Bragg diffraction. By applying a voltage to the positive electrodes via the positive wires, a potential difference can be created between adjacent positive and negative electrodes. A plurality of sets of negative electrodes 425A in the first region 401A, negative electrodes 425B in the second region 401B, negative electrodes 425C in the third region 401C, negative electrodes 425E in the fourth region 401E, and negative electrodes 425E in the fifth region 401E are arranged side by side along the direction of propagation of diffracted light DL due to Bragg diffraction, and are electrically connected to a plurality of ground lines (not shown). The plurality of ground lines are electrically connected to the drive circuit 22. The plurality of positive lines and the plurality of ground lines constitute the wiring EW described above.

[0185] In the spatial light modulation element 600 configured as described above, as in the fourth embodiment, sheet-shaped (elliptical in cross section) processing light EL is incident as incident light on the incident surface 411 of the optical element 410. When no voltage is applied to the plurality of positive electrodes 420A-420E and the plurality of negative electrodes 425A-425E, the sheet-shaped processing light EL that enters the interior of the optical element 410 from the incident surface 411 is totally reflected at the arrangement surface 413 within the optical element 410 and emerges from the emergence surface 412 as zero-order diffracted light.

[0186] When a voltage (a voltage lower than the aforementioned polarization inversion voltage) is applied to multiple sets of positive electrodes 420A-420E arranged along the propagation direction of diffracted light DL due to Bragg diffraction via multiple positive lines (not shown), a first Bragg-diffraction type diffraction grating (not shown) having a pitch direction along the X1 direction is generated in a region where the refractive index changes within the optical element 410 (first polarization portion 415 and second polarization portion 416) located in the first region 401A, as in the fourth embodiment. A second Bragg-diffraction type diffraction grating (not shown) having a pitch direction along the X1 direction is generated in a region where the refractive index changes within the optical element 410 (first polarization portion 415 and second polarization portion 416) located in the second region 401B. A third Bragg-diffraction type diffraction grating (not shown) having a pitch direction along the X1 direction is generated in a region where the refractive index changes within the optical element 410 (first polarization portion 415 and second polarization portion 416) located in the third region 401C. A fourth diffraction grating (not shown) of a Bragg diffraction type having a pitch direction along the X1 direction is generated in a region where the refractive index changes inside the optical member 410 (the first polarized portion 415 and the second polarized portion 416) located in the fourth region 401D. A fifth diffraction grating (not shown) of a Bragg diffraction type having a pitch direction along the X1 direction is generated in a region where the refractive index changes inside the optical member 410 (the first polarized portion 415 and the second polarized portion 416) located in the fifth region 401E.

[0187] With voltages applied to the multiple sets of positive electrodes 420A-420E, the sheet-like processing light EL incident on the incident surface 411 and entering the interior of the optical element 410 is diffracted by Bragg diffraction in the regions where the first to fifth diffraction gratings are generated (i.e., the regions where the refractive index changes). The diffracted light DL (e.g., +1st-order diffracted light) generated by Bragg diffraction is totally reflected at the arrangement surface 413 inside the optical element 410 and emitted from the emission surface 412. In this way, the spatial light modulator 600 modulates the processing light EL incident on the incident surface 411 of the optical element 410 by the potential difference between adjacent positive and negative electrodes, and emits the diffracted light DL from the emission surface 412.

[0188] [Characteristic Configuration of Sixth Embodiment] According to the sixth embodiment, it is possible to obtain the same effects as in the fourth embodiment. Furthermore, in the spatial light modulation element 600 according to the sixth embodiment, the positive electrode 420A in the first region 401A, the positive electrode 420B in the second region 401B, the positive electrode 420C in the third region 401C, the positive electrode 420D in the fourth region 401D, and the positive electrode 420E in the fifth region 401C, which are aligned along the traveling direction of diffracted light DL due to Bragg diffraction, are electrically connected by first to fourth positive side connections 640A to 640D. The negative electrode 425A in the first region 401A, the negative electrode 425B in the second region 401B, the negative electrode 425C in the third region 401C, the negative electrode 425E in the fourth region 401E, and the negative electrode 425E in the fifth region 401E, which are aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction, are electrically connected by first to fourth negative side connections 645A to 645D. This makes it possible to clearly define the boundaries of applied voltage when viewed from the direction of propagation of the diffracted light DL due to Bragg diffraction. Furthermore, as shown by the hatching in Figure 29, by applying a voltage to at least three pairs of positive electrodes 420A to 420E aligned along the direction of propagation of the diffracted light DL due to Bragg diffraction, it is possible to independently modulate a portion of the incident light (processing light EL).

[0189] In the above-described sixth embodiment, as in the fourth embodiment, the optical element 410 may be provided with a slab waveguide configured so that the processing light EL incident from the incident surface 411 passes through a region within the optical element 410 where the refractive index is changed.

[0190] In each of the above-described embodiments, the negative electrode is electrically connected to the drive circuit 22 via a ground line, but this is not limited to this and the negative electrode may also be electrically connected to the drive circuit 22 via a negative line.

[0191] The following supplementary notes are further provided with respect to the above-described embodiments. [Supplementary Note 1] A spatial light modulation element that modulates and emits incident light, comprising: an optical member formed using a light-transmitting ferroelectric material, the optical member having first polarization portions extending along a first axis and second polarization portions extending along the first axis and polarized in a different direction from the first polarization portions and positioned adjacent to the first polarization portions in a direction along a second axis intersecting the first axis; a first electrode provided on a surface of the optical member that intersects with a third axis intersecting the first axis and the second axis; and a second electrode disposed on the surface of the optical member on the side of the first electrode in a direction along the second axis, the spatial light modulation element generating an electric field in the first polarization portions from the first electrode toward the second electrode, thereby changing the refractive index of the first polarization portions along the second axis. [Supplementary Note 2] The spatial light modulation element according to Supplementary Note 1, wherein the incident light passes through a region of the optical member where the refractive index changes along a direction intersecting the second axis. [Supplementary Note 3] The spatial light modulation element according to Supplementary Note 1 or 2, wherein the first electrode and the second electrode are provided in a portion of the surface of the optical element where the first polarization portion is located. [Supplementary Note 4] The spatial light modulation element according to Supplementary Note 3, wherein an electric field directed from the first electrode to the second electrode is generated in the first polarization portion. [Supplementary Note 5] The spatial light modulation element according to Supplementary Note 4, wherein the refractive index differs between a position in the first polarization portion where the first electrode is provided in the direction of the second axis and a position in the first polarization portion where the second electrode is provided in the direction of the second axis. [Supplementary Note 6] The spatial light modulation element according to any one of Supplementary Notes 3 to 5, further comprising: a third electrode arranged on the surface of the optical element on a side of the second electrode in a direction along the second axis; and a fourth electrode arranged on the surface of the optical element on a side of the third electrode in a direction along the second axis, wherein the third electrode and the fourth electrode are provided in a portion of the surface of the optical element where the second polarization portion is located. [Supplementary Note 7] The spatial light modulation element according to any one of Supplementary Notes 1 to 5, wherein the optical member has a third polarization portion that extends along the first axis, is polarized in a direction different from that of the first polarization portion, and is located adjacent to the first polarization portion on the opposite side of the second polarization portion.[Supplementary Note 8] The spatial light modulation element according to Supplementary Note 7, wherein the first electrode is provided at a position on the surface of the optical element that straddles the first polarization portion and the third polarization portion, and the second electrode is provided at a position on the surface of the optical element that straddles the first polarization portion and the second polarization portion. [Supplementary Note 9] The spatial light modulation element according to Supplementary Note 8, further comprising a third electrode provided at a position on the surface of the optical element on the opposite side of the second polarization portion from the two electrodes, wherein an electric field is generated in the first polarization portion from the first electrode to the second electrode, and an electric field is generated in the second polarization portion from the third electrode to the second electrode. [Supplementary Note 10] The spatial light modulation element according to Supplementary Note 6 or 9, wherein the first electrode and the third electrode are electrically connected. [Supplementary Note 11] The spatial light modulation element according to any one of Supplements 1 to 10, wherein a diffraction grating having a pitch direction along the second axis is generated in the optical element by a change in the refractive index in the optical element. [Supplementary Note 12] The spatial light modulation element according to Supplementary Note 11, wherein a first region on the surface of the optical member has a plurality of electrodes that generate the diffraction grating provided along the second axis direction, and a second region on the surface of the optical member adjacent to the first region in the direction along the first axis has a plurality of electrodes that generate the diffraction grating provided along the second axis direction. [Supplementary Note 13] The spatial light modulation element according to Supplementary Note 12, wherein a first diffraction grating generated by the plurality of electrodes in the first region and a second diffraction grating generated by the plurality of electrodes in the second region have mutually different phases of refractive index change. [Supplementary Note 14] The spatial light modulation element according to Supplementary Note 13, wherein the incident light incident on the optical member is Bragg diffracted at the first diffraction grating, and the phase of the refractive index change of the second diffraction grating is equal to the phase of the refractive index change of the first diffraction grating in a direction perpendicular to the propagation direction of the Bragg-diffracted diffracted light. [Supplementary Note 15] The spatial light modulation element according to any one of Supplementary Notes 1 to 14, wherein the optical member includes an incident surface that intersects with the first axis and on which the incident light is incident, and an exit surface that is located on the opposite side of the incident surface in the direction of the first axis and from which light from the optical member is exited.[Supplementary Note 16] The spatial light modulation element according to Supplementary Note 15, wherein the incident light incident from the entrance surface is totally reflected at the positions of the first and second electrodes on the surface of the optical element and exits from the exit surface. [Supplementary Note 17] The spatial light modulation element according to Supplementary Note 15, wherein the optical element includes a slab waveguide arranged so that the incident light incident from the entrance surface passes through a region in the optical element where the refractive index is changed. [Supplementary Note 18] An optical unit comprising: the spatial light modulation element according to any one of Supplements 1 to 17; and an optical system into which diffracted light exiting from the spatial light modulation element is incident, the optical system having a light attenuation section that attenuates at least one of a zeroth-order diffracted light in the diffracted light and diffracted light of an order different from the zeroth-order diffracted light. [Supplementary Note 19] An optical processing device that processes an object with processing light from a light source, comprising: the optical unit according to Supplementary Note 18; and an irradiation device that irradiates the object with the processing light from the light source via the optical unit.

[0192] At least some of the components of each of the above-described embodiments can be appropriately combined with at least some of the other components of each of the above-described embodiments. Some of the components of each of the above-described embodiments may not be used.

[0193] The present invention is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the claims and the gist or idea of ​​the invention as can be read from the entire specification, and spatial light modulation elements, optical units, and optical processing devices that involve such modifications are also included in the technical scope of the present invention.

[0194] REFERENCE SIGNS LIST 1 Optical processing device 20 Optical unit 51 Optical processing device (first modified example) 61 Optical processing device (second modified example) 100 Spatial light modulation element (first embodiment) 110 Optical member 111 Incident surface 112 Exit surface 113 Arrangement surface 115 First polarized portion 116 Second polarized portion 117 Diffraction grating 120 Positive electrode 125 Negative electrode 130 Positive line 135 Ground line 119A,119B Slab waveguide 150 Conventional spatial light modulation element 200 Spatial light modulation element (second embodiment) 210 Optical member 211 Incident surface 212 Emitting surface 213 Arrangement surface 215 First polarization portion 216 Second polarization portion 217 Diffraction grating 220 Positive electrode 225 Negative electrode 230 Positive line 235 Ground line 300 Spatial light modulation element (third embodiment) 310 Optical member 311 Incident surface 312 Emitting surface 313 Arrangement surface 315 First polarization portion 316 Second polarization portion 320A to 320C Positive electrodes 325A to 325C Negative electrodes 350 Spatial light modulation element (modified example of third embodiment) 370A to 370C Positive electrodes 375A to 375C Negative electrode 400 Spatial light modulation element (fourth embodiment) 410 Optical member 411 Incident surface 412 Exit surface 413 Arrangement surface 415 First polarized portion 416 Second polarized portion 420A to 420E Positive electrode 425A to 425E Negative electrode 450 Spatial light modulation element (modified example of fourth embodiment) 470A to 470E Positive electrode 475A to 475E Negative electrode 500 Spatial light modulation element (fifth embodiment) 540A First positive side connection 540B Second positive side connection 545A First negative side connection 545B Second negative side connection 600 Spatial light modulation element (sixth embodiment) 640A First positive side connection 640B Second positive side connection 640C Third positive side connection 640D Fourth positive side connection 645A First negative side connection 645B Second negative side connection 645C Third negative side connection 645D Fourth negative side connection EW Wiring,

Claims

1. A spatial light modulation element that modulates incident light and emits the modulated light, an optical member on which the incident light traveling along a first axis is incident and which is formed using a light-transmitting ferroelectric material; first and second electrodes disposed on a surface of the optical element along a second axis intersecting the first axis; and wiring for applying a voltage to at least one of the first and second electrodes so as to create a potential difference between the first and second electrodes.

2. 2. The spatial light modulation element according to claim 1, wherein the incident light is modulated by a potential difference between the first and second electrodes.

3. The spatial light modulation element according to claim 1 , wherein the first and second electrodes are adjacent to each other in a direction along the second axis.

4. The spatial light modulation element according to claim 1 , wherein the surface of the optical member intersects with a third axis that intersects with the first axis and the second axis.

5. The spatial light modulation element according to claim 1 , wherein the refractive index in the optical member changes along the second axis due to the application of the voltage from the wiring.

6. A spatial light modulation element that modulates incident light and emits the modulated light, an optical member on which the incident light traveling along a first axis is incident and which is formed using a light-transmitting ferroelectric material; first and second electrodes disposed on the surface of the optical element along a second axis intersecting the first axis; A spatial light modulation element in which, when a potential difference is generated between the first and second electrodes, the refractive index within the optical member changes along the second axis.

7. 6. The spatial light modulation element according to claim 5, wherein the refractive index differs between a position within the optical element where the first electrode is provided in the direction of the second axis and a position within the optical element where the second electrode is provided in the direction of the second axis.

8. The spatial light modulation element of claim 5 , wherein the change in refractive index within the optical element creates a diffraction grating within the optical element having a pitch direction along the second axis.

9. a plurality of electrodes that generate the diffraction grating are provided along the second axis in the first region of the surface of the optical member; a second region adjacent to the first region on the surface of the optical member in a direction along the first axis, the second region including a plurality of electrodes that generate the diffraction grating and are provided along the second axis; The spatial light modulation element according to claim 8 , wherein the plurality of electrodes includes the first and second electrodes.

10. 10. The spatial light modulation element according to claim 9, wherein a first diffraction grating generated by the plurality of electrodes in the first region and a second diffraction grating generated by the plurality of electrodes in the second region have mutually different phases of refractive index change.

11. the incident light incident on the optical member is Bragg diffracted at the first diffraction grating, 11. The spatial light modulation element according to claim 10, wherein the phase of the refractive index change of the second diffraction grating is equal to the phase of the refractive index change of the first diffraction grating in a direction perpendicular to the propagation direction of the Bragg-diffracted diffracted light.

12. The spatial light modulation element according to claim 5 , wherein the incident light that has entered the optical member passes through a region in the optical member where the refractive index changes along a direction intersecting the second axis.

13. The optical member is a first polarizing portion extending along the first axis; A spatial light modulation element according to any one of claims 1 to 12, having a second polarization portion extending along the first axis and polarized in a direction different from that of the first polarization portion, and positioned adjacent to the first polarization portion on the side along the second axis.

14. The spatial light modulation element according to claim 13 , wherein the first and second electrodes are provided on the surface of the optical member at a portion where the first polarized portion is located.

15. The spatial light modulation element according to claim 14 , wherein an electric field is generated in the first polarized portion from the first electrode toward the second electrode.

16. 16. The spatial light modulation element according to claim 15, wherein the refractive index is different between a position in the optical element where the first electrode is provided in the direction of the second axis and a position in the optical element where the second electrode is provided in the direction of the second axis.

17. The spatial light modulation element according to claim 14 , further comprising third and fourth electrodes provided on the surface of the optical member at a portion where the second polarized portion is located.

18. The first electrode and the third electrode are electrically connected, The spatial light modulation element according to claim 17 , wherein the second electrode and the fourth electrode are electrically connected to each other.

19. The spatial light modulation element according to claim 13, wherein the optical element has a third polarization portion extending along the first axis, polarized in a direction different from the first polarization portion, and positioned adjacent to the first polarization portion on the opposite side of the second polarization portion.

20. the first electrode is provided at a position on the surface of the optical member that spans the first polarized portion and the third polarized portion, The spatial light modulation element according to claim 19 , wherein the second electrode is provided at a position on the surface of the optical member that straddles the first polarized portion and the second polarized portion.

21. a third electrode provided on the surface of the optical member on the opposite side of the second polarizing portion from the second electrode; an electric field is generated in the first polarized portion from the first electrode toward the second electrode; 20. The spatial light modulation element according to claim 19, wherein an electric field directed from the third electrode to the second electrode is generated in the second polarized portion.

22. The spatial light modulation element according to claim 17 , wherein the first electrode and the third electrode are electrically connected.

23. The spatial light modulation element according to any one of claims 1 to 12, wherein the optical element has an incident surface that intersects with the first axis and on which the incident light is incident, and an exit surface that is located on the opposite side of the incident surface in the direction of the first axis and from which light from the optical element is emitted.

24. 24. The spatial light modulation element according to claim 23, wherein the incident light incident on the entrance surface is totally reflected at the positions of the first and second electrodes on the surface of the optical member and is emitted from the exit surface.

25. a refractive index within the optical member changes along the second axis upon application of a voltage to at least one of the first and second electrodes; 24. The spatial light modulation element according to claim 23, wherein the optical element comprises a slab waveguide configured so that the incident light entering from the incident surface passes through a region in the optical element where the refractive index changes.

26. The spatial light modulation element according to any one of claims 1 to 12; an optical system onto which the diffracted light emitted from the spatial light modulation element is incident, The optical system is an optical device having a light-attenuating section that attenuates at least one of a zeroth-order diffracted light in the diffracted light and a diffracted light of an order different from the zeroth-order diffracted light.

27. An optical processing device that processes an object with processing light from a light source, an optical device according to claim 26; an irradiation device that irradiates the object with processing light from the light source via the optical device.

28. a refractive index within the optical member changes along the second axis upon application of a voltage to at least one of the first and second electrodes; 28. The optical processing apparatus according to claim 27, further comprising a shaping optical system that shapes the beam cross-sectional shape of the processing light from the light source so that the processing light from the light source passes through a region in the optical element where the refractive index changes along a direction intersecting the second axis.