Optical modulator, optical unit, and optical processing device

Abstract

Provided is an optical modulator (30) for modulating and emitting incident light, the optical modulator (30) comprising: a substrate formed from a ferroelectric optical crystal (31); pixel electrodes (32) and control electrodes (33) arranged on an upper surface of the substrate; and a control device (60) that controls a voltage to be applied to the control electrodes (33). The ferroelectric optical crystal (31) has a periodic polarity reversal structure provided with a plurality of regions having alternating directions of polarization. A voltage is applied between each of the pixel electrodes (32) and a common electrode (34) disposed on a surface on the opposite side to the surface where said pixel electrode (32) is disposed, and the electric field thus generated within the ferroelectric optical crystal (31) induces a change in refractive index to form a diffraction grating. When applying a voltage to a pixel electrode (32), the control device (60) applies a voltage to a control electrode (33) adjacent to said pixel electrode (32).

Description

Optical modulator, optical unit and optical processing device

[0001] The present invention relates to an optical modulator, an optical unit, and an optical processing device.

[0002] An electro-optic spatial light modulation element is known, for example, from Patent Document 1. Such spatial light modulation elements are required to produce high optical output.

[0003] U.S. Pat. No. 8,175,422

[0004] An optical modulator according to a first aspect of the present invention is an optical modulator that modulates and emits incident light, and includes a substrate made of a ferroelectric optical crystal onto which the incident light is incident from a first direction, electrodes arranged on two surfaces of the ferroelectric optical crystal on both sides of the substrate along a second direction intersecting the first direction, and a control circuit that controls voltages applied to the electrodes, wherein the ferroelectric optical crystal has a periodic polarization inversion structure in which a plurality of regions in which the direction of polarization alternates are arranged along the second direction, and the electrode arranged on one of the two surfaces includes a plurality of pixel electrodes arranged along the second direction and a control electrode arranged between the plurality of pixel electrodes in the second direction, and each of the pixel electrodes applies a voltage between itself and an electrode arranged on the other of the two surfaces opposite to the pixel electrode, thereby changing the refractive index due to an electric field generated in the ferroelectric optical crystal to form a diffraction grating, and the control circuit applies a voltage to the control electrode adjacent to the pixel electrode when applying a voltage to the pixel electrode.

[0005] An optical modulator according to a second aspect of the present invention is an optical modulator that modulates and emits incident light, and includes a substrate made of a ferroelectric optical crystal into which the incident light is incident from a first direction, and electrodes arranged on two surfaces of the ferroelectric optical crystal on both sides of the substrate along a second direction intersecting with the first direction, the ferroelectric optical crystal having a periodic polarization inversion structure in which a plurality of regions in which the direction of polarization alternates are arranged along the second direction, the electrode arranged on one of the two surfaces includes a plurality of pixel electrodes arranged along the second direction and a control electrode arranged between the plurality of pixel electrodes in the second direction, each of the pixel electrodes changes its refractive index by applying a voltage between the pixel electrode and an electrode on the surface opposite to the pixel electrode, thereby generating an electric field within the ferroelectric optical crystal, thereby forming a diffraction grating, and the region on the substrate in which one of the plurality of pixel electrodes is formed overlaps with one or more boundaries of the plurality of regions of the periodic polarization inversion structure when viewed from a third direction intersecting with the first direction and the second direction.

[0006] The optical unit of the present invention comprises the above-mentioned optical modulator and an optical system into which diffracted light emitted from the optical modulator is incident, and the optical system has an attenuation section that attenuates 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 apparatus of the present invention is an optical processing apparatus that processes an object using processing light EL from a light source, and is equipped with the above-mentioned optical unit and an irradiation device that irradiates the object with processing light EL from the light source via the optical unit.

[0008] FIG. 1 is a schematic diagram showing an optical processing apparatus. FIG. 2 is a cross-sectional view showing a processing optical system, which is part of the optical processing apparatus. FIG. 3 is a perspective view showing the configuration of an optical modulator. FIG. 4 is a plan view and a cross-sectional view showing the configuration of the optical modulator. FIG. 5 is an enlarged view of a portion of the substrate shown in FIG. 4. FIG. 6 shows the polarization components of the processing light EL incident on the optical modulator. FIG. 7 is a perspective view showing the configuration of an optical modulator according to a modified example. FIG. 8 is a top view and a cross-sectional view showing the configuration of an optical modulator according to a modified example. FIG. 9 is a cross-sectional view partially showing the electrode structure of an optical modulator according to a modified example. FIG. 10 is an exploded view of the electrode structure of the optical modulator. FIG. 11 is a cross-sectional view showing the processing optical system according to a second embodiment. FIG. 12 shows the configuration of an optical processing apparatus equipped with a polarization intensity balancer. FIG. 13 is a cross-sectional view showing the processing optical system according to a fourth embodiment. FIG. 14 shows a simulation model. FIG. 15 shows the relationship between beam diameter and pixel electrode. FIG. 16 shows the simulation results of the voltage distribution when all channels are turned on (100 V). Figure 17 shows the simulation results of the voltage distribution when only the center channel is turned ON (100V) and the channels on both sides are turned OFF. Figure 18 shows the simulation results of the voltage distribution when only the center channel is turned OFF and the channels on both sides are turned ON (100V). Figure 19 shows the optical system used for the beam shape simulation. Figure 20 shows the beam shape simulation results.

[0009] Preferred embodiments will be described below. First, an optical unit and an optical processing device equipped with an optical modulator according to each embodiment will be described using Fig. 1. In the description of the optical processing device, the directions indicated by the arrows in Fig. 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 each other.

[0010] First Embodiment FIG. 1 is a diagram illustrating an optical processing apparatus 1 including an optical modulator 30. The optical processing apparatus 1 is an optical processing apparatus that performs additive processing, for example, a device that performs modeling using powder bed fusion (PBF). As shown in FIG. 1 , the optical processing apparatus 1 includes a light source 5, a processing optical system 10, an irradiation device 50, a control device 60, and a supply mechanism 70. The optical processing apparatus 1 performs additive processing by irradiating a modeling material M1 supplied by the supply mechanism 70 with processing light EL to form a three-dimensional model 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.

[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 a femtosecond laser, or pulsed light having a pulse width longer than that of a femtosecond laser. In this embodiment, the processing light EL emitted by the light source 5 is randomly polarized.

[0012] The processing light EL may be a type of light other than laser light, as long as it can form a three-dimensional object SC when irradiated onto the modeling material M1. The wavelength range of the processing light EL may be any wavelength range, as long as it can form a three-dimensional object SC when irradiated onto the modeling material M1. For example, the wavelength range of the processing light EL may be the wavelength range of visible light, the wavelength range of infrared light (e.g., 1064 nm), or the wavelength range of ultraviolet light.

[0013] FIG. 2 is a cross-sectional view showing a processing optical system, which is a part of the optical processing apparatus 1. The upper part of FIG. 2 is a view of the processing optical system 10 of the optical processing apparatus 1 as viewed from the Z direction, and the lower part is a view of the processing optical system 10 of the optical processing apparatus 1 as viewed from the X direction. Processing light EL emitted from a 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 light EL (e.g., five processing light EL aligned in the X direction) and emits them toward an irradiation device 50. The multiple processing light EL emitted from the processing optical system 10 are irradiated onto a modeling material M1 via the irradiation device 50. The direction along the optical axis of the processing optical system 10 is defined as the Y direction, the horizontal direction perpendicular to the Y direction is defined as the X direction, and the direction perpendicular to the Y direction and the X direction is defined as the Z direction.

[0014] The processing optical system 10 includes, arranged in order from the light source 5 side, a double-telecentric zoom lens 11, a diffractive optical element 12, a collector lens 13, a collimator lens 14, a polarizing beam splitter (PBS) 15, a half-wave plate 16, a cylindrical lens 17, an optical modulator 30 having a spatial light modulation function, a cylindrical lens 18, a half-wave plate 19, a polarizing beam combiner (PBC) 20, two lens arrays 21 and 22, a first relay lens 23, an aperture 24, and a second relay lens 25.

[0015] The double-telecentric zoom lens 11 changes the beam spot size without changing the beam pitch. This double-telecentric zoom lens 11 may also be referred to as an afocal zoom lens, whose angular magnification can be changed. The processing light EL from the light source 5 passes through the double-telecentric zoom lens 11 and is incident on the diffractive optical element 12. The diffractive optical element 12 diffracts the incident processing light EL, splitting it into multiple processing light beams EL. In the example shown in FIG. 1 , the diffractive optical element 12 splits the incident processing light EL into a processing light EL that travels along the optical axis of the processing optical system 10 and four processing light beams EL that travel at an angle in the ±X direction relative to the optical axis of the processing optical system 10. In other words, the processing light EL that is incident on the processing optical system is split into five processing light beams EL.

[0016] 1, the diffractive optical element 12 divides the processing light EL incident on the diffractive optical element 12 into five processing light beams EL, but the configuration of the diffractive optical element 12 is not limited to this. The diffractive optical element 12 may divide the processing light EL incident on the diffractive optical element 12 into two or more processing light beams EL, for example, may divide the processing light EL into seven processing light beams EL. Furthermore, the diffractive optical element 12 is not limited to dividing the processing light EL into multiple processing light beams EL arranged one-dimensionally (in a row), but may divide the processing light EL so that the multiple processing light beams EL are arranged two-dimensionally.

[0017] The plurality of processing light beams EL emitted from the diffractive optical element 12 are incident on the collector lens 13. The front focal position of the collector lens 13 may be located on the grating plane of the diffractive optical element 12. The collector lens 13 makes the traveling directions of the plurality of processing light beams EL passing through the collector lens 13 parallel to each other. The collector lens 13 also focuses each of the processing light beams EL passing through the collector lens 13.

[0018] A plurality of collimator lenses 14 are arranged side by side in the X direction in alignment with the plurality of processing light beams EL. As shown in FIG. 1 , if the diffractive optical element 12 splits the processing light beam EL into five beams of light, five collimator lenses 14 may be arranged side by side in the X direction. A plurality of processing light beams EL that have passed through the collector lenses 13 are incident on the plurality of collimator lenses 14. The front focal position of each collimator lens 14 may be located on the rear focal plane of the collector lenses 13. The collimator lenses 14 convert the processing light beam EL that passes through the collimator lenses 14 into parallel light.

[0019] The polarizing beam splitter 15 separates the incident light beam into P-polarized light (parallel polarization) and S-polarized light (vertical polarization). In FIG. 1 , light polarized in a direction perpendicular to the paper surface (i.e., the vibration direction of the electric field of the light, i.e., the electromagnetic wave) is referred to as P-polarized light, and light polarized in a direction parallel to the paper surface is referred to as S-polarized light. As shown in FIG. 1 , when the diffractive optical element 12 splits the processing light EL into five beams, five polarizing beam splitters 15 may be arranged in the X direction. The polarizing beam splitter 15 transmits the S-polarized component and reflects the P-polarized component, outputting it parallel to the S-polarized component. The half-wave plate 16 is provided on the path of the S-polarized component of the beam splitter. The half-wave plate 16 converts the S-polarized component separated by the polarizing beam splitter 15 into a P-polarized component.

[0020] A cylindrical lens 17 is disposed downstream of the polarizing beam splitter 15. The cylindrical lens 17 focuses the P-polarized component emitted from the polarizing beam splitter 15 and the P-polarized component converted from the S-polarized component by the half-wave plate in the Z direction, and guides them to the incident surface of the optical modulator 30. Here, the rear focal position of the cylindrical lens 17 may be located on or near the surface on which the electrodes of the optical modulator 30 are formed.

[0021] The optical modulator 30 is irradiated with the P-polarized components of the processing light EL that have passed through the cylindrical lens 17. The optical modulator 30 has a substrate made of a ferroelectric optical crystal that transmits the processing light EL in the Y direction. The processing light EL that passes through the substrate is modulated by applying a voltage to electrodes provided on both surfaces of the substrate in the Z direction. The drive circuit 61 is electrically connected to the electrodes provided on the optical modulator 30 via wiring EW, and is capable of applying a voltage to each electrode of the optical modulator 30.

[0022] When no voltage is applied to the electrodes of the optical modulator 30, the optical modulator 30 emits the processing light EL incident on the optical modulator 30 as zeroth-order diffracted light toward the cylindrical lens 18 located downstream. When a voltage is applied to the electrodes of the optical modulator 30, the processing light EL incident on the optical modulator 30 is diffracted to generate diffracted light of a predetermined order (e.g., +1st or −1st order). Furthermore, when a voltage is applied to some of the electrodes of the optical modulator 30, the processing light EL passing through the area corresponding to that electrode is diffracted to generate diffracted light of the predetermined order. A more detailed configuration of the optical modulator 30 will be described later. Hereinafter, diffracted light of a predetermined order will be described using first-order diffracted light as an example.

[0023] The processing light EL (zeroth-order diffracted light or first-order diffracted light) emitted from the optical modulator 30 is incident on the cylindrical lens 18. The cylindrical lens 18 focuses the processing light EL emitted from the optical modulator 30 in the Z direction. Here, the front focal position of the cylindrical lens 18 may coincide with or nearly coincide with the rear focal position of the cylindrical lens 17. The divergent processing light EL that has passed through the front focal position of the cylindrical lens 18 is converted into a parallel beam and guided to the polarization beam combiner 20.

[0024] A half-wave plate 19 is disposed on the path from the cylindrical lens 18 to the polarization beam combiner 20. The half-wave plate 19 is disposed on the path corresponding to the half-wave plate 16 provided in the polarization beam splitter 15. The half-wave plate 19 converts the P-polarized component emitted from the optical modulator 30 into an S-polarized component. The S-polarized component separated by the polarization beam splitter 15 was converted into a P-polarized component before entering the optical modulator 30, and the wave plate 19 performs a process to convert the converted P-polarized component back into an S-polarized component. The randomly polarized processed light EL is converted into P-polarized light before entering the optical modulator 30 in this manner because the optical modulator 30 used in this embodiment is a device that effectively modulates the P-polarized component.

[0025] The polarization beam combiner 20 combines the P-polarized component and the S-polarized component to form a single processing light EL. The combined processing light EL is incident on a first relay lens 23 via two lens arrays 21 and 22. As shown in FIG. 1 , when the diffractive optical element 12 splits the processing light EL into five beams, the lenses constituting the lens arrays 21 and 22 may be arranged in a row of five in the X direction. The lens arrays 21 and 22 may be positioned so that the rear focal position of one lens in the lens array 21 coincides with the front focal position of a corresponding lens in the lens array 22. Here, the lens arrays 21 and 22 may be considered as an optical system that expands or reduces the beam diameter of each of the multiple incident processing light beams EL while maintaining the spacing between the multiple processing light beams EL.

[0026] The first relay lens 23 focuses the incident processing light EL. An aperture 24 is disposed at the focal position of the first relay lens 23, and the zeroth-order diffracted light transmitted through the optical modulator 30 passes through the opening of the aperture 24. The first-order diffracted light diffracted by the optical modulator 30 is blocked by the diaphragm plate of the aperture 24. Because the first-order diffracted light modulated by the optical modulator 30 is blocked, multiple (here, five) processing light beams EL can be switched on and off depending on whether or not they are modulated. Alternatively, the first-order diffracted light may be transmitted while the zeroth-order diffracted light is blocked. In this case, when the optical modulator 30 is off (no voltage is applied), all light is blocked as the zeroth-order diffracted light. Therefore, when the optical modulator 30 is on, light finally begins to pass through the aperture, resulting in modulated light with a high extinction ratio (on / off ratio).

[0027] Although it has been stated above that the processing light EL can be switched on and off, this refers to the case where only zeroth-order diffracted light or only first-order diffracted light is generated by modulation in the optical modulator 30. The optical modulator 30 can also generate both zeroth-order diffracted light and first-order diffracted light by adjusting the voltage applied to it. In this case, the aperture 24 blocks the first-order diffracted light component and passes the zeroth-order diffracted light component, so the intensity of the processing light EL can be continuously changed by adjusting the amount of zeroth-order diffracted light.

[0028] The aperture 24 is water-cooled to prevent a temperature rise of the aperture 24 due to irradiation of the processing light EL onto the diaphragm plate. Note that instead of the aperture 24, a neutral density filter with an opening in the center may be provided so that the amount of diffracted light is significantly reduced by the neutral density filter. The aperture 24 that blocks first-order diffracted light and the neutral density filter that reduces the amount of first-order diffracted light are neutral density units that attenuate first-order diffracted light.

[0029] The processing light EL that passes through the aperture 24 is incident on the second relay lens 25. An image generated by the second relay lens 25 is projected onto the processing surface made of the modeling material M. Specifically, an irradiation device 50 is provided after the second relay lens 25, and projects the image of the second relay lens 25 onto the processing surface. Of the configuration described above, the light modulator 30 and the optical system from the light modulator 30 to the second relay lens 25 constitute an optical unit 28 that attenuates at least one of the zeroth-order diffracted light and the first-order diffracted light.

[0030] A plurality of beams of processing light EL that have passed through the second relay lens 25 are incident on the irradiation device 50. The irradiation device 50 irradiates the plurality of beams of processing light EL that have entered the irradiation device 50 onto the modeling material M1. As shown in FIG. 1 , the irradiation device 50 includes, in order from the light source 5 side, a condenser lens 51, a galvanometer mirror 52, and a scanning optical system 53. Here, the condenser lens 51 and the scanning optical system 53 of the irradiation device 50 constitute an imaging optical system, and the condenser lens 51 and the scanning optical system 53 re-image, on the surface of the modeling material M1, images of a plurality of focused spots formed by the plurality of beams of processing light EL on the intermediate imaging plane 26.

[0031] The focusing lens 51 focuses the processing light EL emitted from the second relay lens 25 onto the galvanometer mirror 52. The galvanometer mirror 52 changes the emission direction of the processing light EL by swinging or rotating its reflecting surface to change the angle of the processing light EL relative to the optical path. The change in the emission direction of the processing light EL by the galvanometer mirror 52 is converted by the scanning optical system 53 into a change in the irradiation position of the processing light EL. Therefore, by changing the emission direction of the processing light EL by the galvanometer mirror 52, the irradiation position (focusing position) of the processing light EL on the modeling material M1 can be changed. This allows the galvanometer mirror 52 to scan the surface of the modeling material M1 with the processing light EL. Note that instead of the galvanometer mirror 52, a polygon scanner, an acousto-optical element, or the like may be used to scan the surface of the modeling material M1 with the processing light EL.

[0032] The processing light EL emitted from the galvanometer mirror 52 is incident on the scanning optical system 53. The scanning optical system 53 focuses the processing light EL from the galvanometer mirror 52 onto the surface of the modeling material M1. That is, the scanning optical system 53 irradiates the surface of the modeling material M1 with the convergent processing light EL. The scanning optical system may also include a field lens that adjusts the beam profile of the processing light EL and an fθ lens that focuses the processing light EL deflected by the galvanometer mirror 52 on the machining surface.

[0033] Now, when the diameter of the processing light EL incident on the diffractive optical element 12 is changed by the above-mentioned double telecentric zoom lens 11, the diameter of the multiple processing light EL emitted from the diffractive optical element 12 changes, and as a result, the opening angle of the multiple processing light EL focused on the processing surface (the surface of the modeling material M1) changes. Therefore, the size of the irradiation area (focused spot) of the multiple processing light EL irradiated on the processing surface changes.

[0034] 1 and 2, and FIGS. 11 and 13 described later, a plane optically conjugate with the processing surface (surface of the modeling material M1) is indicated by a dashed dotted line.

[0035] The control device 60 is configured using, for example, a CPU (Central Processing Unit), a memory (not shown), etc. The control device 60 controls the operations of the light source 5, the drive circuit 61, the galvanometer mirror 52, etc. based on a control program stored in the memory.

[0036] The supply mechanism 70 includes a build piston 71A and a build cylinder 71B, a feed piston 72A and a feed cylinder 72B, and a leveling roller 73. The build piston 71A and the build cylinder 71B are disposed below the scanning optical system 53. The build piston 71A is attached inside the build cylinder 71B so as to be able to reciprocate up and down. The feed piston 72A and the feed cylinder 72B are disposed side by side with the build piston 71A and the build cylinder 71B.

[0037] The feed piston 72A is arranged inside the feed cylinder 72B so as to be able to reciprocate vertically. The build material M1 is stored above the feed piston 72A inside the feed cylinder 72B. The leveling roller 73 is arranged so as to be able to reciprocate substantially horizontally between the upper edge of the feed cylinder 72B and the upper edge of the build cylinder 71B. The leveling roller 73 rolls from the upper edge of the feed cylinder 72B to the upper edge of the build cylinder 71B, thereby pushing and supplying the build material M1 stored above the feed piston 72A above the build piston 71A. The control device 60 controls the operation of the supply mechanism 70 in addition to the light source 5, the drive circuit 61, the galvanometer mirror 52, etc. The supply mechanism 70 may also include a squeegee instead of the leveling roller 73.

[0038] In the optical processing apparatus 1, the supply mechanism 70 repeatedly supplies a layer of the modeling material M1 having a predetermined thickness above the build piston 71A inside the build cylinder 71B each time the processing light EL is irradiated. At this time, the build piston 71A moves downward by a distance equal to the predetermined thickness, and the feed piston 72A moves upward together with the modeling material M1 stored above the feed piston 72A. The leveling roller 73 then pushes the modeling material M1 protruding from the upper edge of the feed cylinder 72B above the build piston 71A. This results in a layer of the modeling material M1 having a predetermined thickness being supplied above the build piston 71A inside the build cylinder 71B. 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.

[0039] [Configuration of Optical Modulator] Figure 3 is a perspective view showing the configuration of optical modulator 30, and Figure 4 is a top view and a cross-sectional view showing the configuration of optical modulator 30. Optical modulator 30 has a ferroelectric optical crystal 31 to which incident light is incident from the Y direction. For convenience of explanation, the +Z direction will be referred to as the up direction and the -Z direction as the down direction below. Insulating layers 35 and 36 made of, for example, SiO2 are attached to the top and bottom surfaces of ferroelectric optical crystal 31. The ferroelectric optical crystal 31 and insulating layers 35 and 36 form a substrate.

[0040] In this embodiment, the ferroelectric optical crystal 31 is an MgO:LN (MgO-doped lithium niobate) crystal. The material of the ferroelectric optical crystal 31 is not limited to MgO:LN, and other materials such as an LN crystal, an LT (lithium tantalate) crystal, or an MgO:SLT (MgO-doped stoichiometric lithium tantalate) crystal can be used.

[0041] A plurality of pixel electrodes 32 are arranged along the X direction on the upper surface of the substrate. Here, an example is given in which the pixel electrodes 32 are arranged along the X direction, but the direction in which the pixel electrodes 32 are arranged does not necessarily have to be perpendicular to the Y direction, and may be a direction that intersects with the Y direction at an angle other than a right angle. The distance g between the pixel electrodes 32 ｅis the distance g between the two surfaces of the substrate in the Z direction ｔ On the upper surface of the substrate, a control electrode 33 is further disposed between each of the pixel electrodes 32. On the other hand, on the lower surface of the substrate, a common electrode 34 is disposed to cover the entire surface.

[0042] The ferroelectric optical crystal 31 has a periodically poled structure consisting of multiple regions in which the direction of polarization alternates. Fig. 5 is an enlarged view of a portion (region R) of the substrate shown in Fig. 4. The ferroelectric optical crystal 31 has multiple first polarized portions 31a extending in the Z direction and multiple second polarized portions 31b adjacent to the first polarized portions 31a and extending in the Z direction, arranged alternately along the X direction. The second polarized portions 31b are polarized in the opposite direction to the first polarized portions 31a.

[0043] To form a periodic polarization reversal structure in the ferroelectric optical crystal 31, the polarization direction of the portion corresponding to the second polarization portion 31b is reversed by 180° in the ferroelectric optical crystal 31, which is formed in a rectangular parallelepiped shape and has uniform polarization (dielectric polarization). For example, when using a known method called the "electric field application method," an electrode is attached to the portion corresponding to the second polarization portion 31b, and a voltage above a certain level (also called a polarization reversal voltage or coercive field) is applied, thereby reversing the polarization direction of the second polarization portion 31b.

[0044] Here, the widths of the pixel electrode 32 and the first and second polarization portions 31a and 31b in the X direction will be described. A pair of the first polarization portion 31a and the second polarization portion 31b is referred to as a "period" of the periodic polarization inversion structure. The width of the pixel electrode 32 along the X direction is three or more periods of the periodic polarization inversion structure. As an example, one period of the periodic polarization inversion structure is 0.02 mm, and the width of the pixel electrode 32 in the X direction is 4.6 mm. The region on the substrate where one of the pixel electrodes 32 is formed overlaps with one or more of the boundaries of the multiple regions of the periodic polarization inversion structure when viewed from the Z direction. Because the region corresponding to the pixel electrode 32 has a polarization inversion structure with multiple periods, applying a voltage to the pixel electrode 32 can generate diffracted light. For example, when performing intensity modulation of a multi-beam, it is possible to improve diffraction efficiency while providing pixel performance with good channel separation and a high extinction ratio. It should be noted that FIG. 5 is a schematic diagram showing a periodically poled structure, and therefore does not accurately represent the width of the period of the periodically poled structure.

[0045] Applying a voltage between the pixel electrode 32 and the common electrode 34 generates an electric field within the ferroelectric optical crystal 31, which changes the refractive index of the ferroelectric optical crystal 31 and forms a diffraction grating. The formation of the diffraction grating diffracts the processed light EL incident on the ferroelectric optical crystal 31, resulting in the emission of first-order diffracted light. The first-order diffracted light is generated for the processed light EL that passes through the region between the pixel electrode 32 and the common electrode 34 to which a voltage is applied. However, no first-order diffracted light is generated for the processed light EL that passes through the region between the pixel electrode 32 and the common electrode 34 to which no voltage is applied, and the processed light EL passes through the ferroelectric optical crystal 31 as zeroth-order diffracted light.

[0046] However, if the distance between pixel electrodes 32 is reduced to increase the number of channels, or if the crystal thickness of the ferroelectric optical crystal 31 is increased to increase the beam diameter, the voltage applied to a pixel electrode 32 may affect adjacent pixel electrodes 32.

[0047] The optical modulator 30 of this embodiment includes a control electrode 33 between each pixel electrode 32. When a voltage is applied to a pixel electrode 32, a voltage is also applied to the control electrode 33 adjacent to that pixel electrode 32. By placing the control electrodes 33 between the pixel electrodes 32 in this manner and controlling the voltage applied to the control electrodes 33, it is possible to reduce crosstalk while narrowing the channel spacing. Because the electric field from the pixel electrodes 32 on the upper surface of the substrate spreads before reaching the common electrode 34 on the lower surface of the substrate, the control electrode 33 configuration is particularly effective when the crystal thickness is thick (e.g., 300 to 500 μm or more). The configuration of the optical modulator 30 of this embodiment allows for an increase in the number of channels while maintaining high-performance modulation characteristics.

[0048] Although an example has been given here in which a voltage is applied to the adjacent control electrode 33 when a voltage is applied to a pixel electrode 32, a configuration is also possible in which a voltage is applied to the control electrode 33 when a voltage is applied to pixel electrodes 32 on both sides of the control electrode 33, and no voltage is applied to the control electrode 33 when a voltage is applied to only one of the pixel electrodes 32. Even if no voltage is applied to the control electrode 33, the flow of the electric field from the pixel electrode 32 is directed toward the adjacent control electrode 33, so that the effect of reducing or blocking the flow of the electric field to the adjacent pixel electrode 32 can be expected.

[0049] As shown in Figure 2, in this embodiment, two lights, the P-polarized component of one processed light EL and the P-polarized component converted from the S-polarized component, are input to adjacent pixel electrodes 32 of the optical modulator 30, and the P-polarized component emitted from the optical modulator 30 is returned to one processed light EL combined by the polarization beam combiner 20.

[0050] FIG. 6 is a diagram showing the polarization components of the processed light EL incident on the optical modulator 30. As can be seen from FIG. 6, the two pixel electrodes of the optical modulator 30 are involved in the combined light. For example, when a voltage is applied to both the pixel electrodes 32a and 32b, first-order diffracted light is generated from the P-polarized and S-polarized components, and the combined light combined by the polarization beam combiner 20 is also first-order diffracted light. For example, when no voltage is applied to both the pixel electrodes 32a and 32b, the P-polarized and S-polarized components pass through the optical modulator 30 as zeroth-order diffracted light, and the combined light is zeroth-order diffracted light. In this way, zeroth-order diffracted light is generated when both the pixel electrodes 30a and 30b are off, and first-order diffracted light is generated when both the pixel electrodes 30a and 30b are on.

[0051] When a voltage is applied to one of the pixel electrodes 32a and 32b and no voltage is applied to the other, the combined light is a mixture of zeroth-order diffracted light and first-order diffracted light. In this way, the pixel electrode 32 of this embodiment controls one pixel using two pixel electrodes 32a and 32b. Therefore, it can be said that multiple electrodes that control one pixel are arranged in the X direction.

[0052] While it has been described that the intensity of the processing light EL can be adjusted by adjusting the amount of the zeroth-order diffracted light using the optical modulator 30, the optical modulator 30 can also adjust the amount of the P-polarized component and the S-polarized component. For example, if there is a difference in magnitude between the P-polarized component and the S-polarized component separated by the polarizing beam splitter 15, the optical modulator 30 can adjust the voltage applied to the pixel electrodes 32 a, 32 b so that the zeroth-order diffracted light generated from the P-polarized light and the zeroth-order diffracted light generated from the S-polarized light have the same magnitude.

[0053] [Modification of Optical Modulator] Figure 7 is a perspective view showing the configuration of an optical modulator 30 according to a modification, and Figure 8 is a top view and a cross-sectional view showing the configuration of the optical modulator 30 according to a modification. The basic configuration of the optical modulator 30 is the same as the optical modulator 30 described with reference to Figures 3 to 5. The optical modulator 30 according to the modification has a configuration in which the control electrodes 33 arranged between the pixel electrodes 32 are connected to each other, enabling the same voltage control. This makes it possible to appropriately prevent crosstalk between the pixel electrodes 32 with a simple configuration.

[0054] Fig. 9 is a cross-sectional view partially showing the electrode structure of an optical modulator 30 according to a modified example, and Fig. 10 is an exploded view of the electrode structure of the optical modulator 30. In Figs. 9 and 10, the bottom surface of the substrate is shown facing up and the top surface of the substrate is shown facing down. Here, the electrode structure of the optical modulator according to the modified example will be described, but the electrode structure of an optical modulator 30 (see Figs. 3 to 5) having an independent control electrode 33 between pixel electrodes 32 is also the same as the structure described here.

[0055] The electrode structure includes a ceramic spacer 37 that covers the pixel electrodes 32 and control electrodes 33 on the upper surface of the substrate, and a ceramic electrode substrate 38 on top of that. An opening 39 is formed in the ceramic spacer 37 at a position corresponding to the pixel electrode 32, and a probe terminal 40 is inserted into this opening 39. The probe terminal 40 and the pixel electrode 32 are in surface contact, which distributes the stress caused by the probe terminal 40 abutting against the pixel electrode 32, making the pixel electrode 32 less likely to crack. A probe pin 40 a of the probe terminal 40 is connected to a pad 43 on the ceramic electrode substrate 38.

[0056] A plurality of sets of wiring layers 41 and GND layers 42 are formed on the ceramic electrode substrate 38. Pads 43 and predetermined wiring layers 41 are electrically connected through vias 44. An area having wiring lead-out terminals 45 for leading out wiring from the wiring layers 41 is formed at the end of the ceramic electrode substrate 38 in the X direction.

[0057] Second Embodiment Next, an optical processing apparatus according to a second embodiment will be described. In the first embodiment, randomly polarized processing light EL is incident on the processing optical system, but in the optical processing apparatus according to the second embodiment, processing light EL consisting of a P-polarized component is incident on the processing optical system.

[0058] 11 is a cross-sectional view showing a processing optical system according to the second embodiment. The processing optical system 10 includes, arranged in order from the light source 5 side, a double-telecentric zoom lens 11, a diffractive optical element 12, a collector lens 13, a collimator lens 14, a cylindrical lens 17, a light modulator 30 having a spatial light modulation function, a cylindrical lens 18, a first relay lens 23, an aperture 24, and a second relay lens 25. The components included in the processing optical system of the second embodiment have the same functions as those in the processing optical system of the first embodiment, which are designated by the same reference numerals.

[0059] In the second embodiment, since the processing light EL is made up of a P-polarized component, the polarizing beam splitter 15, which separates the P-polarized component from the randomly polarized light, and the half-wave plate 16, which converts the S-polarized component separated from the randomly polarized light into a P-polarized component, are not required. The half-wave plate 19 and the polarization beam combiner 20 downstream of the optical modulator 30 are also not required. Furthermore, since the processing light EL is not separated into a P-polarized component and an S-polarized component, the length of the optical modulator 30 in the X direction is also shortened. Furthermore, the lens arrays 21 and 22 between the optical modulator 30 and the first relay lens 23 in the first embodiment are also not required. As such, the processing optical system of the optical processing apparatus of the second embodiment can be realized with a simpler configuration than the optical processing apparatus 1 of the first embodiment.

[0060] 12 is a diagram showing the configuration of an optical processing apparatus according to a third embodiment. The optical processing apparatus according to the third embodiment includes a polarization intensity balancer 80 that adjusts the polarization state of the laser between the fiber laser 6, which is the light source, and the scan units 1 a and 1 b.

[0061] Generally, when the power of a laser is changed, the polarization direction and ellipticity may change. It is also known that the polarization state changes over time in the initial stage of laser irradiation. The polarization intensity balancer 80 has the function of absorbing changes in the polarization state of the laser emitted from the fiber laser 6. A detailed configuration of the polarization intensity balancer 80 is described in U.S. Patent Publication No. 2022 / 203477. In the optical processing apparatus of the third embodiment, the processing light EL output from the polarization intensity balancer 80 is split by a polarizing beam splitter 90 and is incident on each of the two scan units 1a and 1b.

[0062] [Polarization Intensity Balancer] The polarization intensity balancer 80 includes a polarizing beam splitter 81, quarter-wave plates 82 and 84, reflecting mirrors 83 and 85, and a wave plate 86 to adjust or stabilize the intensity of the processing light EL. The processing light EL from the fiber laser 6 is incident on the polarizing beam splitter 81, where it is separated into an S-polarized component and a P-polarized component. The S-polarized light reflected by the polarizing beam splitter passes through the quarter-wave plate 82. As a result, the S-polarized light is converted into circularly polarized light. The circularly polarized light that passed through the quarter-wave plate 82 is reflected by the reflecting mirror 83. The circularly polarized light reflected by the reflecting mirror 83 passes through the quarter-wave plate 82 again and is converted into P-polarized light. The P-polarized light that passed through the quarter-wave plate 82 is incident on the polarizing beam splitter 81.

[0063] On the other hand, the P-polarized light reflected by the polarizing beam splitter passes through the quarter-wave plate 84 and is converted into circularly polarized light. The circularly polarized light that passed through the quarter-wave plate 84 is reflected by the reflecting mirror 85. The circularly polarized light reflected by the reflecting mirror 85 passes through the quarter-wave plate 84 again and is converted into S-polarized light. The S-polarized light that passed through the quarter-wave plate 84 is incident on the polarizing beam splitter 81.

[0064] The P-polarized light and S-polarized light that enter the polarizing beam splitter 81 are reflected in the same direction by the polarizing beam splitter 81, aligning the optical paths of the P-polarized light and the S-polarized light. In other words, the optical paths of the P-polarized light and the S-polarized light that exit the polarizing beam splitter 81 overlap. The polarizing beam splitter 81 emits a combined light of the P-polarized light and the S-polarized light. Because the polarization intensity balancer 80 overlaps the two polarized lights separated by the polarizing beam splitter 81, even if there is an imbalance between the S-polarized light and the P-polarized light, such as when one of the S-polarized light and the P-polarized light is strong and the other is weak, the combined light is balanced and has a constant intensity.

[0065] The combined light emitted by the polarizing beam splitter 81 is incident on the wave plate 86. The wave plate 86 is an optical element that can change the polarization state of the combined light passing through the wave plate 86. The wave plate 86 is, for example, a quarter-wave plate, but may be another type of wave plate (for example, at least one of a half-wave plate, a one-eighth-wave plate, and a one-wave plate). For example, the wave plate 86 may be capable of converting the combined light into circularly polarized light (or polarized light other than linearly polarized light or unpolarized light). If the wave plate 86 is a quarter-wave plate, the wave plate 86 can convert the linearly polarized combined light into circularly polarized light. Alternatively, even if the wave plate 86 is not a quarter-wave plate, the wave plate 86 can convert the combined light into circularly polarized light (or polarized light other than linearly polarized light or unpolarized light) if the characteristics of the wave plate 86 are appropriately set.

[0066] The optical processing apparatus of the third embodiment has a polarization intensity balancer 80 between the fiber laser 6 and the scanner units 1a and 1b, thereby realizing an optical processing apparatus that is less susceptible to the influence of polarization state due to changes in laser power, etc.

[0067] Fourth Embodiment Next, an optical processing apparatus according to a fourth embodiment will be described. In the third embodiment, the processing light that has passed through the polarization intensity balancer 80 is split by the polarizing beam splitter 90 and incident on the two scan units 1 a and 1 b. However, in the processing apparatus according to the fourth embodiment, a plurality of optical modulators, typically two, are provided in one scan unit.

[0068] Fig. 13 is a cross-sectional view showing a processing optical system according to the fourth embodiment. The upper part of Fig. 13 is a view of the processing optical system 10 of the optical processing apparatus 1 as seen from the Z direction, and the lower part is a view of the processing optical system 10 as seen from the X direction. In Fig. 13, components having the same functions as those in the first embodiment are denoted by the same reference numerals. In the following explanation, in order to avoid redundant explanation, the configuration from the collimator lens 14 to the cylindrical lens 18 will be explained.

[0069] 13, the multiple beams of processing light EL that have been converted into nearly parallel beams by the collimator lens 14 are incident on a cylindrical lens 17. The multiple beams of processing light EL that have been condensed in the Z direction in the figure by the cylindrical lens 17 are incident on a polarizing beam splitter 15A. The S-polarized component of the processing light that becomes S-polarized with respect to the polarization splitting surface of the polarizing beam splitter 15A is reflected by this polarization splitting surface, and the P-polarized component of the processing light that becomes P-polarized with respect to this polarization splitting surface is transmitted through the polarizing beam splitter 15A.

[0070] The S-polarized light components of the processing light beams reflected by the polarization splitting surface of the polarizing beam splitter 15A each pass through a half-wave plate 101 to be converted into P-polarized light components, and then are reflected by the optical path bending mirror 102 and enter the optical modulator 30A1. Meanwhile, the P-polarized light components of the processing light beams transmitted through the polarizing beam splitter 15A enter the optical modulator 30A2. Here, the directions of travel of the P-polarized light components of the processing light beams transmitted through the polarizing beam splitter 15A and the P-polarized light components of the processing light beams reflected by the optical path bending mirror 102 are substantially parallel to each other. The configurations of the optical modulators 30A1 and 30A2 are similar to the configuration of the optical modulator 30 described above, and therefore will not be described here.

[0071] The processing light EL emitted from the optical modulator 30A1 enters the polarization beam combiner 20A. The processing light EL emitted from the optical modulator 30A2 is reflected by the optical path bending mirror 103, passes through a half-wave plate, is converted into an S-polarized component, and enters the polarization beam combiner 20A. The polarization beam combiner 20A has a polarization combining surface that reflects the S-polarized component and transmits the P-polarized component. The polarization beam combiner 20A reflects the S-polarized processing light EL from the optical modulator 30A1 and transmits the P-polarized processing light EL from the optical modulator 30A2. These multiple processing light beams EL are focused in the Z direction by the cylindrical lens 18 and proceed toward the first relay lens 23.

[0072] In the fourth embodiment, the optical modulators 30A1 and 30A2 are arranged in an optically corresponding positional relationship. That is, the points where the rear focal position of the cylindrical lens 17 and the front focal position of the cylindrical lens 18 coincide are located on each of the two optical paths between the polarizing beam splitter 15A and the polarizing beam combiner 20A, and the surfaces on which the electrodes of the optical modulators 30A1 and 30A2 are formed are positioned at these coincident points. The optical modulators 30A1 and 30A2 are positioned so that the pitch directions of the pixel electrodes 32 are parallel to each other. Therefore, when the optical modulators 30A1 and 30A2 are driven with the same control signal (a set of voltages applied to each of the pixel electrodes 32), the diffracted light from the optical modulators 30A1 and 30A2 is generated in the same state, and the diffracted light from the optical modulators 30A1 and 30A2 that have passed through the polarizing beam combiner 20A overlap spatially.

[0073] In the above description, the optical modulators 30A1 and 30A2 are controlled by the same control signal, but the optical modulators 30A1 and 30A2 may be driven so as to eliminate individual differences.

[0074] Therefore, even if the polarization state of the processing light EL from the light source 5 fluctuates, it does not affect the modulation state of the processing light from the polarization beam combiner 20A.

[0075] In addition, a quarter-wave plate may be placed in the optical path between the polarized beam combiner 20A and the processing surface (the surface of the molding material M1) to make the polarization state of the processing light EL irradiated onto the processing surface a circular polarization state.

[0076] According to the fourth embodiment, the degree of freedom in selecting the light source 5 can be improved.

[0077] The following shows the results of a simulation of the voltage distribution in the optical modulator of this embodiment. 1. Simulation Model Figure 14 is a diagram showing the simulation model. Two control electrodes between pixel electrodes are controlled together. For three beams, the period of the periodically poled structure is 20 μm, and Bragg diffraction is assumed. The pitch between channels is set to 1 mm to reduce the calculation area. The control electrodes are common and connected to GND. RSoft's BeamPROP was used for the calculation.

[0078] Figure 15 shows the relationship between the beam diameter and the pixel electrode. In the simulation, the horizontal width was reduced. The channel pitch was 1 mm, the control electrode width was 200 μm, and the pixel electrode width was 600 μm.

[0079] 2. Voltage Distribution Simulation Results Figure 16 shows the results of a simulation of voltage distribution when all channels are turned on (100 V). The upper row shows the voltage distribution of the present invention, and the lower row shows the voltage distribution of the comparative example. It can be seen that by setting the control electrode 33 to GND (0 V), there is no influence from the voltage of adjacent channels, and crosstalk occurs very little, resulting in good separation between channels.

[0080] Figure 17 shows the simulation results of the voltage distribution when only the center channel is turned ON (100V) and the channels on both sides are turned OFF. The upper row shows the voltage distribution of the present invention, and the lower row shows the voltage distribution of the comparative example. It can be seen that the presence of the control electrode 33 results in almost no change compared to the voltage distribution when all channels are ON. On the other hand, without the control electrode 33, the voltage distribution becomes wider.

[0081] Figure 18 shows the results of a simulation of the voltage distribution when only the center channel is turned OFF and the channels on both sides are turned ON (100 V). The upper row shows the voltage distribution of the present invention, and the lower row shows the voltage distribution of the comparative example. In this case, too, it can be seen that the presence of the control electrode 33 results in almost no change compared to the voltage distribution when all channels are ON. On the other hand, without the control electrode 33, the center channel is affected by the spread of the voltage distribution on both sides, causing crosstalk.

[0082] The results of a beam shape simulation using the optical modulator of this embodiment are shown below. 1. Simulation Model Figure 19 is a diagram showing the optical system used in the beam shape simulation. Three adjacent beams were incident on the optical modulator, Bragg diffracted, and only the zeroth-order diffracted light (transmitted light) was subjected to electromagnetic optical calculations using RSoft's BeamPROP. The complex amplitude data immediately after exiting the modulator was Fourier transformed and then inverse Fourier transformed through a frequency filter to obtain the beam shape. The channel pitch remained at 1 mm, and the beam size was 500 μm horizontal (half maximum) and 250 μm vertical (half maximum), with three conditions of 1.0×, 1.22×, and 1.41×.

[0083] 2. Simulation Results Figure 20 shows the results of the beam shape simulation. The horizontal axis represents the beam arrangement axis, and the vertical axis represents light intensity. To allow for a clear overview, a perspective view of the beam shape is shown in the upper right corner of each condition. The top three show cases where there is no control electrode, and the bottom three show cases where the control electrode is set to 0 V. The middle two show cases where -15 V is applied to the control electrode 33. Starting from the leftmost row, the beam sizes are arranged in the order of 1.0x, 1.22x, and 1.41x, with a channel pitch of 1 mm, and a horizontal beam size of 500 μm (half value) and a vertical beam size of 250 μm (half value).

[0084] The point to note is the minimum level of light intensity between the beams. The lower the minimum level of light intensity, the better the separation between the channels. Comparing the minimum levels of light intensity, it is clear that channel separation is better when the control electrode 33 is inserted and controlled than when no control electrode 33 is used. The best results are obtained by actively controlling the control electrode by applying a potential to it, but it can be seen that sufficient effects can be expected even when the control electrode 33 is simply grounded.

[0085] The following supplementary notes are further provided with respect to the above-described embodiment: [Supplementary Note 1] An optical modulator that modulates and emits incident light, comprising: a substrate made of a ferroelectric optical crystal onto which the incident light is incident from a first direction; electrodes arranged on two surfaces of the ferroelectric optical crystal on both sides of the substrate along a second direction intersecting the first direction; and a control circuit that controls voltages applied to the electrodes, wherein the ferroelectric optical crystal has a periodically poled structure in which a plurality of regions whose polarization directions alternate are provided along the second direction, the electrode arranged on one of the two surfaces includes a plurality of pixel electrodes arranged along the second direction and a control electrode arranged between the plurality of pixel electrodes in the second direction, each of the pixel electrodes changes its refractive index by applying a voltage between itself and an electrode arranged on the other of the two surfaces opposite to the pixel electrode, thereby generating an electric field in the ferroelectric optical crystal to change the refractive index, thereby forming a diffraction grating, and the control circuit applies a voltage to the control electrode adjacent to the pixel electrode when applying a voltage to the pixel electrode. [Supplementary Note 2] The optical modulator according to Supplementary Note 1, wherein an electric field flows from the pixel electrode toward the control electrode when a voltage is applied to the pixel electrode. [Supplementary Note 3] An optical modulator that modulates and emits incident light, comprising: a substrate made of a ferroelectric optical crystal into which the incident light is incident from a first direction; and electrodes arranged on two opposing surfaces of the substrate of the ferroelectric optical crystal along a second direction intersecting the first direction, the ferroelectric optical crystal having a periodically poled structure in which a plurality of regions whose polarization direction alternates are provided along the second direction, the electrodes arranged on one of the two surfaces include a plurality of pixel electrodes arranged along the second direction and a plurality of control electrodes arranged between the plurality of pixel electrodes in the second direction, the pixel electrode changes its refractive index by applying a voltage between the pixel electrode and an electrode on the surface opposite to the pixel electrode, thereby forming a diffraction grating, and the electric field flows from the pixel electrode toward the control electrode when a voltage is applied to the pixel electrode.[Supplementary Note 4] The optical modulator according to any one of Supplementary Notes 1 to 3, wherein the width of the pixel electrode along the second direction is three times or more the width along the second direction of a pair of two adjacent regions among the plurality of regions of the periodically poled structure. [Supplementary Note 5] A distance g between two surfaces on both sides of the substrate. ｔ (However, 50 μm≦g ｔ ≦5000 μm) and the gap distance g between adjacent pixel electrodes ｅ is the distance g ｅ ≦distance g ｔ The optical modulator according to any one of Supplementary Notes 1 to 4, which satisfies the following: [Supplementary Note 6] The period of the region of the periodically poled structure is Λ ｐｐ , the width W of the pixel electrode in the second axis direction ｅ is 3Λ ｐｐ ≦W ｅ[Supplementary Note 7] The optical modulator according to any one of Supplementary Notes 1 to 6, wherein a region on the substrate in which one of the pixel electrodes is formed and one or more boundaries among the boundaries of the plurality of regions of the periodic polarization inversion structure overlap when viewed from a third direction intersecting the first direction and the second direction. [Supplementary Note 8] An optical modulator that modulates and emits incident light, comprising: a substrate made of a ferroelectric optical crystal into which the incident light is incident from a first direction; and electrodes arranged on two surfaces of the ferroelectric optical crystal on both sides of the substrate along a second direction intersecting with the first direction, wherein the ferroelectric optical crystal has a periodically poled structure in which a plurality of regions whose polarization directions alternate are provided along the second direction, the electrodes arranged on one of the two surfaces include a plurality of pixel electrodes arranged along the second direction, and a control electrode arranged between the plurality of pixel electrodes in the second direction, wherein a voltage is applied between the pixel electrode and an electrode on the surface opposite to the pixel electrode to change the refractive index due to an electric field generated in the ferroelectric optical crystal, thereby forming a diffraction grating, and wherein a region on the substrate in which one of the plurality of pixel electrodes is formed and one or more boundaries of the plurality of regions of the periodically poled structure overlap when viewed from a third direction intersecting with the first direction and the second direction. [Supplementary Note 9] The optical modulator according to Supplementary Note 8, wherein a plurality of the control electrodes are provided, each disposed between the plurality of pixel electrodes, and the plurality of control electrodes are connected to each other so as to be capable of controlling the same voltage. [Supplementary Note 10] The optical modulator according to any of Supplements 1 to 9, wherein the diffraction grating formed in the substrate of the ferroelectric optical crystal has a pitch along the second direction. [Supplementary Note 11] The optical modulator according to any of Supplements 1 to 10, wherein one or more of the pixel electrodes are composed of a plurality of electrodes. [Supplementary Note 12] The optical modulator according to any of Supplements 1 to 11, wherein the width of the control electrode in the second direction is narrower than the width of the pixel electrode in the second direction.[Supplementary Note 13] An optical modulator that modulates and emits incident light, comprising: a substrate made of a ferroelectric optical crystal onto which the incident light is incident from a first direction; and electrodes arranged on two opposing surfaces of the substrate of the ferroelectric optical crystal along a second direction intersecting with the first direction, wherein the ferroelectric optical crystal has a periodic polarization inversion structure in which a plurality of regions, the direction of polarization of which alternates, are provided along the second direction, and the electrodes arranged on one of the two surfaces include a plurality of pixel electrodes arranged along the second direction, and a plurality of control electrodes arranged between the plurality of pixel electrodes in the second direction, wherein the pixel electrodes change their refractive index by applying a voltage between the pixel electrodes and an electrode on the opposing surface thereof, thereby generating an electric field in the ferroelectric optical crystal, thereby forming a diffraction grating, and wherein the width of the control electrodes in the second direction is narrower than the width of the pixel electrodes in the second direction. [Supplementary Note 14] An optical unit comprising: an optical modulator according to any one of Supplements 1 to 13; and an optical system into which diffracted light emitted from the optical modulator is incident, the optical system having a light attenuation unit 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. [Supplementary Note 15] An optical processing device that processes an object with processing light from a light source, comprising: the optical unit according to Supplementary Note 14; and an irradiation device that irradiates the object with the processing light from the light source via the optical unit.

[0086] 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.

[0087] The present invention is not limited to the above-described embodiments, but 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 optical modulators, optical units, and optical processing devices that involve such modifications are also included in the technical scope of the present invention.

[0088] REFERENCE SIGNS LIST 1 Optical processing device 1a, 1b Scanner unit 5 Light source 6 Fiber laser 10 Processing optical system 11 Double telecentric zoom lens 12 Diffractive optical element 13 Collector lens 14 Collimator lens 15 Polarizing beam splitter 16 Half-wave plate 17 Cylindrical lens 18 Cylindrical lens 19 Half-wave plate 20 Polarized beam combiner 21 Lens array 22 Lens array 23 First relay lens 24 Aperture 25 Second relay lens 30 Optical modulator 31 Ferroelectric optical crystal 32 Pixel electrode 33 Control electrode 34 Common electrode 35 Insulating layer 36 Insulating layer 37 Ceramic spacer 38 Ceramic electrode substrate 39 Opening 40 Probe terminal 40a Probe pin 40a 41 Wiring layer 42 GND layer 43 Pad 44 Via 50 Irradiation device 51 Galvanometer mirror 52 Scanning optical system 60 Control device 61 Drive circuit 70 Supply mechanism 71A Build piston 71B Build cylinder 72A Feed piston 72B Feed cylinder 73 Leveling roller 80 Polarization intensity balancer 81 Polarizing beam splitter 82 1 / 4 wavelength plate 83 Reflecting mirror 84 1 / 4 wavelength plate 85 Reflecting mirror 86 Wave plate 90 Polarizing beam splitter 91 Reflecting mirror

Claims

1. An optical modulator that modulates and emits incident light, comprising: a substrate made of a ferroelectric optical crystal onto which the incident light is incident from a first direction; electrodes arranged on two surfaces of the ferroelectric optical crystal on both sides of the substrate along a second direction intersecting the first direction; and a control circuit that controls voltages applied to the electrodes, wherein the ferroelectric optical crystal has a periodic polarization inversion structure in which a plurality of regions whose polarization directions alternate are arranged along the second direction, the electrodes arranged on one of the two surfaces include a plurality of pixel electrodes arranged along the second direction and a control electrode arranged between the plurality of pixel electrodes in the second direction, each of the pixel electrodes applying a voltage between itself and an electrode arranged on the surface opposite to the pixel electrode, thereby changing the refractive index due to an electric field generated in the ferroelectric optical crystal to form a diffraction grating, and the control circuit applies a voltage to the control electrode between the two pixel electrodes when applying a voltage to two adjacent pixel electrodes of the plurality of pixel electrodes.

2. The optical modulator according to claim 1, wherein when a voltage is applied to the pixel electrode, an electric field flows from the pixel electrode toward the control electrode.

3. An optical modulator according to claim 1 or 2, wherein the width of the pixel electrode along the second direction is at least three times the width along the second direction of a pair of two adjacent regions among the plurality of regions of the periodic polarization inversion structure.

4. The distance g between the two surfaces on both sides of the substrate ｔ (However, 50 μm≦g ｔ ≦5000 μm) and the gap distance g between adjacent pixel electrodes ｅ is the distance g ｅ ≦distance g ｔ 4. The optical modulator according to claim 1, wherein the above formula (1) is satisfied.

5. The period of the region of the periodically poled structure is Λ ｐｐ , the width W of the pixel electrode in the second direction ｅ is 3Λ ｐｐ ≦W ｅ 5. The optical modulator according to claim 1, wherein the above formula (1) is satisfied.

6. An optical modulator according to any one of claims 1 to 5, wherein an area on the substrate in which one of the pixel electrodes is formed and one or more of the boundaries of the plurality of areas of the periodic polarization inversion structure overlap when viewed from a third direction intersecting the first direction and the second direction.

7. An optical modulator that modulates and emits incident light, comprising: a substrate made of a ferroelectric optical crystal onto which the incident light is incident from a first direction; and electrodes arranged on two surfaces of the ferroelectric optical crystal on both sides of the substrate along a second direction intersecting with the first direction, wherein the ferroelectric optical crystal has a periodic polarization inversion structure in which a plurality of regions whose polarization direction alternates are provided along the second direction, and the electrodes arranged on one of the two surfaces include a plurality of pixel electrodes arranged along the second direction and a control electrode arranged between the plurality of pixel electrodes in the second direction, and each of the pixel electrodes changes its refractive index by applying a voltage between the pixel electrode and an electrode on the surface opposite to the pixel electrode, thereby generating an electric field within the ferroelectric optical crystal, thereby forming a diffraction grating, and wherein a region on the substrate in which one of the plurality of pixel electrodes is formed and one or more boundaries of the plurality of regions of the periodic polarization inversion structure overlap when viewed from a third direction intersecting with the first and second directions.

8. An optical modulator according to claim 7, wherein a plurality of said control electrodes are provided, each of said control electrodes being disposed between said plurality of pixel electrodes, and said plurality of control electrodes are connected to each other so that the same voltage control can be performed.

9. An optical modulator according to any one of claims 1 to 8, wherein the diffraction grating formed in the substrate of the ferroelectric optical crystal has a pitch along the second direction.

10. An optical modulator according to any one of claims 1 to 9, wherein at least one of said pixel electrodes is composed of a plurality of electrodes.

11. An optical modulator according to any one of claims 1 to 10, wherein the width of said control electrode in said second direction is narrower than the width of said pixel electrode in said second direction.

12. An optical unit comprising: an optical modulator according to any one of claims 1 to 11; and an optical system into which diffracted light emitted from said optical modulator is incident, said optical system having a light-attenuating section that attenuates at least one of the zeroth-order diffracted light in said diffracted light and diffracted light of an order different from said zeroth-order diffracted light.

13. An optical processing device for processing an object with processing light from a light source, comprising: an optical unit according to claim 12; and an irradiation device for irradiating the object with the processing light from the light source via the optical unit.

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