Optical device and three-dimensional shaping device

Abstract

A second optical system (23) of this optical device comprises a short-axis-side light shielding portion (236), a third lens (233), a long-axis-side light shielding portion (235), a fourth lens (234), and a scanning mechanism (237). The long-axis-side light shielding portion (235) is disposed at a long axis side condensing position, resulting from the third lens (233), of a modulated beam (L33). The long-axis-side light shielding portion (235) blocks long axis side non-zero-order diffracted light of the modulated beam (L33). The scanning mechanism (237) is disposed between the third lens (233) and the fourth lens (234), adjacent to the long-axis-side light shielding portion (235). The scanning mechanism (237) scans the modulated beam (L33) that is incident on the long-axis-side light shielding portion (235) or the modulated beam (L33) that has passed through the long-axis-side light shielding portion (235) in at least one of the long axis direction and the short axis direction. As a result, the structure of the optical device (12) can be simplified.

Description

Optical device and three-dimensional modeling device

[0001] The present invention relates to an optical device that irradiates and scans a spot light array on an object, and a three-dimensional modeling apparatus that includes the optical device. [Reference to Related Applications] This application claims the benefit of priority from Japanese Patent Application JP2023-215365, filed on December 21, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] In recent years, SLS (Selective Laser Sintering) type three-dimensional modeling devices have been used, which irradiate a modeling material such as metal powder or resin powder with modulated laser light and sinter the modeling material to create a three-dimensional shape.

[0003] For example, in the three-dimensional object manufacturing apparatus disclosed in Japanese Patent Laid-Open No. 2011-127192 (Document 1), a laser beam irradiation unit 61 provided above a powder layer irradiates and scans a single spot of laser beam onto the top surface of the powder layer. The laser beam irradiation unit 61 includes an optical fiber connector 83 connected to a laser oscillator, a collimating lens 85 that converts the laser beam emitted from the optical fiber connector 83 into parallel beams, a galvano optical scanner 89 that is a scanning mechanism that performs two-dimensional scanning with the laser beam that has passed through the collimating lens 85, and an Fθ lens 99 that focuses the laser beam scanned by the galvano optical scanner 89 and irradiates the powder layer.

[0004] In addition, in order to improve productivity in three-dimensional modeling devices, it is being considered to use an optical modulator to form a line-shaped pattern of light and to scan the modeling material by simultaneously irradiating it with multiple light spots (i.e., by irradiating it with a spot light array).

[0005] In a three-dimensional modeling device that emits a spot light array, a light modulator that forms a line-shaped pattern of light is irradiated with high-power-density light in order to increase the power density (i.e., light intensity per unit area) of the laser light irradiated onto the modeling material. In this case, if the light modulator is irradiated with line-shaped laser light having a Gaussian intensity distribution, the peak intensity (i.e., maximum intensity) on the modulation surface of the modulator becomes excessive, which may damage the light modulator.

[0006] Therefore, in the three-dimensional modeling device of Patent Publication No. 2021-165769 (Document 2), it is proposed to increase the amount of light input to the optical modulator without damaging the optical modulator by flattening the intensity distribution of the linear laser light incident on the optical modulator using a top-hat beam shaper.

[0007] In the three-dimensional printing apparatus of Document 2, the illumination optical system and the projection optical system each include a relatively large number of lenses, etc. In addition, although not described in detail in Document 2, the scanning unit of the three-dimensional printing apparatus needs to include a plurality of optical elements (i.e., collimator lenses, galvanometer scanners, Fθ lenses, etc.) similar to those of Document 1 in order to image and scan the linear laser light that has passed through the projection optical system onto the upper surface of the printing material (i.e., the scanned surface). For this reason, in the three-dimensional printing apparatus, there is a limit to how simply the structure of the optical device that guides the laser light emitted from the light source to the scanned surface of the printing material for scanning is simplified.

[0008] The present invention is directed to a technology for irradiating and scanning an array of spot lights onto an object, and aims to simplify the structure of an optical device.

[0009] Aspect 1 of the present invention is an optical device that irradiates an object with a spot light array for scanning, and includes a first optical system that shapes laser light into a shaped beam that is long in the major axis direction, an optical modulator that modulates the shaped beam and forms a modulated beam having a pattern in the major axis direction, and a second optical system that guides the modulated beam to a scanned surface of the object to form a spot light array on the scanned surface that extends in the major axis direction, and scans the spot light array on the scanned surface. The second optical system includes a minor axis side light shielding portion that is arranged at a light-converging position on the minor axis side of the modulated beam and that blocks non-zero order diffracted light on the minor axis side of the modulated beam, a first projection optical element that is arranged between the minor axis side light shielding portion and the scanned surface and that focuses the modulated beam in the major axis direction, a major axis side light shielding portion that is arranged at a light-converging position on the major axis side of the modulated beam by the first projection optical element between the first projection optical element and the scanned surface and that blocks non-zero order diffracted light on the major axis side of the modulated beam, and a second projection optical element that is arranged between the major axis side light shielding portion and the scanned surface. a second projection optical element arranged adjacent to the long-axis side light-shielding portion and configured to converge the modulated beam that has passed through the long-axis side light-shielding portion in the short-axis direction and collect the beam on the scanned surface, thereby forming a spot light array on the scanned surface, and a scanning mechanism arranged adjacent to the long-axis side light-shielding portion between the first projection optical element and the second projection optical element and configured to scan the modulated beam that is incident on the long-axis side light-shielding portion or the modulated beam that has passed through the long-axis side light-shielding portion in at least one of the long-axis direction and the short-axis direction. The second optical system makes the modulation surface of the optical modulator and the scanned surface optically conjugate with each other in the long-axis direction.

[0010] According to the present invention, the structure of the optical device can be simplified.

[0011] A second aspect of the present invention is the optical device of the first aspect, wherein the scanning mechanism is a galvanometer scanner that changes the reflection direction of the modulated beam.

[0012] Aspect 3 of the present invention is an optical device of aspect 2, wherein the galvanometer scanner comprises a first galvanometer mirror arranged adjacent to the long axis side shading portion between the first projection optical element and the long axis side shading portion, and which rotates to change the reflection direction of the modulated beam in one of the long axis direction and the short axis direction, and a second galvanometer mirror arranged adjacent to the long axis side shading portion between the long axis side shading portion and the second projection optical element, and which rotates to change the reflection direction of the modulated beam in the other of the long axis direction and the short axis direction.

[0013] A fourth aspect of the present invention is the optical device of the third aspect, wherein the first galvanometer mirror changes the reflection direction of the modulated beam in the minor axis direction.

[0014] Aspect 5 of the present invention is the optical device of Aspect 1 (which may be any one of Aspects 1 to 4), wherein the first optical system includes a beam shaper that converts the intensity distribution of the laser light in the major axis direction from a Gaussian distribution, thereby making the intensity distribution of the shaped beam in the major axis direction at the modulation plane a top hat distribution.

[0015] A sixth aspect of the present invention is the optical device of the fifth aspect, wherein the beam shaper converts the intensity distribution of the laser light in the minor axis direction from a Gaussian distribution, so that the intensity distribution of the shaped beam in the minor axis direction on the modulation plane also becomes a top-hat distribution.

[0016] Aspect 7 of the present invention is the optical device of aspect 1 (which may be any one of aspects 1 to 6), in which no optical element is disposed between the scanning mechanism and the long axis side light blocking portion.

[0017] Aspect 8 of the present invention is the optical device of aspect 1 (which may be any one of aspects 1 to 7), in which the optical modulator is a PLV.

[0018] Aspect 9 of the present invention is a three-dimensional modeling device comprising an optical device according to any one of aspects 1 to 8, a laser light source that emits the laser light to the optical device, and a material holding unit that holds a modeling material, which is the object that is irradiated with the modulated beam from the optical device.

[0019] The above and other objects, features, aspects and advantages will become more apparent from the following detailed description of the invention which proceeds with reference to the accompanying drawings.

[0020] FIG. 1 is a diagram showing the configuration of a three-dimensional modeling device according to a first embodiment; FIG. 2 is a diagram showing the structure of an optical modulator; FIG. 3 is a diagram showing the structure of an optical device and optical paths in the optical device; FIG. 4 is a diagram showing the structure of an optical device and optical paths in the optical device; FIG. 5 is a perspective view showing a minor axis side light-shielding part; FIG. 6 is a perspective view showing a major axis side light-shielding part; FIG. 7 is a diagram showing the structure of an optical device according to a second embodiment and optical paths in the optical device; FIG. 8 is a diagram showing the structure of an optical device and optical paths in the optical device;

[0021] FIG. 1 is a diagram showing the configuration of a three-dimensional modeling apparatus 1 according to a first embodiment of the present invention. The three-dimensional modeling apparatus 1 is a selective laser sintering (SLS) type three-dimensional modeling apparatus that irradiates a powdered or paste-like modeling material with modulated laser light to sinter or melt the modeling material, thereby performing three-dimensional modeling. The modeling material may be, for example, metal, engineering plastic, ceramic, or synthetic resin. The modeling material may contain multiple types of materials.

[0022] The three-dimensional modeling apparatus 1 includes a laser light source 11, an optical device 12, and a material supply mechanism 14. FIG. 1 illustrates the material supply mechanism 14 in a longitudinal cross section. In the three-dimensional modeling apparatus 1, the laser light L31 emitted from the laser light source 11 is guided by the optical device 12 to the material supply mechanism 14 and scanned onto the modeling material 91 in the modeling space 140 of the material supply mechanism 14. As a result, the portion of the modeling material 91 irradiated with the laser light is sintered. Then, a three-dimensional model is formed by repeatedly supplying the modeling material 91 to the modeling space 140 and scanning the modeling material 91 with the laser light. In FIG. 1, each component of the optical device 12 is surrounded by a two-dot chain line to facilitate understanding of the drawing.

[0023] In the 3D printing apparatus 1, the components of the laser light source 11, the optical device 12, the material supply mechanism 14, etc. are controlled by a control unit (not shown) based on design data (e.g., CAD data) of the 3D object to be manufactured. The control unit is, for example, a typical computer including a processor, a memory, an input / output unit, and a bus. Note that the configuration of the control unit may be modified in various ways.

[0024] The laser light source 11 emits laser light L31 to the optical device 12. The laser light source 11 is, for example, a fiber laser light source. The wavelength of the laser light L31 is, for example, 1.070 μm. The type of the laser light source 11 and the wavelength of the laser light L31 may be changed in various ways.

[0025] The optical device 12 modulates the laser light L31 from the laser light source 11 into a modulated beam L33 and irradiates the modulated beam L33 onto an upper surface 92 (hereinafter also referred to as the "scanned surface 92") of the building material 91 in the building space 140. On the scanned surface 92, a spot light array in which multiple spot light beams are arranged in a substantially straight line is formed by the modulated beam L33 guided by the optical device 12. The optical device 12 also scans the spot light array over the scanned surface 92.

[0026] The optical device 12 includes a first optical system 21, an optical modulator 22, and a second optical system 23. As described below, the first optical system 21 and the second optical system 23 each include a plurality of optical elements such as lenses. The first optical system 21 is an illumination optical system that guides the laser light L31 from the laser light source 11 to the optical modulator 22. The second optical system 23 is an optical system that incorporates a scanning mechanism that scans the modulated beam L33 over the scanned surface 92 within a projection optical system that guides the modulated beam L33 from the optical modulator 22 to the scanned surface 92 of the building material 91.

[0027] The first optical system 21 shapes the laser light L31 from the laser light source 11 into a substantially rectangular shaped beam L32 that is long in one direction (hereinafter referred to as the "long axis direction") and guides it to the optical modulator 22. In other words, the cross-sectional shape of the shaped beam L32 is a substantially rectangular shape that is long in the long axis direction and short in the short axis direction perpendicular to the long axis direction. The shaped beam L32 refers to the light beam that passes through the first optical system 21 and enters the optical modulator 22.

[0028] The above-mentioned major axis direction and minor axis direction are directions perpendicular to the traveling direction of the shaped beam L32 (i.e., the optical axis direction). Furthermore, the cross-sectional shape of the shaped beam L32 refers to the shape of the shaped beam L32 on a plane perpendicular to the optical axis direction of the shaped beam L32. In the following description, the cross section of light refers to the cross section of the light on a plane perpendicular to the optical axis direction of the light, as described above. The cross-sectional shape of the shaped beam L32 can also be considered to be a substantially linear shape extending in the major axis direction. The shape of the irradiation area of ​​the shaped beam L32 on the optical modulator 22 is, for example, a substantially rectangular shape with a length in the major axis direction of approximately 28 mm and a length in the minor axis direction of approximately 1 mm.

[0029] The optical modulator 22 modulates the shaped beam L32 from the first optical system 21 to form a modulated beam L33 having a pattern in the major axis direction, and guides the modulated beam L33 to the second optical system 23. As the optical modulator 22, for example, an LPLV (Linear Planar Light Valve), which is a type of PLV (Planar Light Valve), is used.

[0030] FIG. 2 is a simplified diagram showing the structure of the optical modulator 22 (i.e., LPLV). The optical modulator 22 includes a plurality of substantially rectangular pixels 221 arranged adjacent to each other in a matrix (i.e., two-dimensionally arranged) on a substrate (not shown). In the optical modulator 22, the surfaces of the plurality of pixels 221 serve as modulation surfaces. In the example shown in FIG. 2, M pixels 221 are arranged vertically and N pixels 221 are arranged horizontally. The horizontal direction in FIG. 2 corresponds to the major axis direction of the shaped beam L32 (see FIG. 1), and the vertical direction in FIG. 2 corresponds to the minor axis direction of the shaped beam L32.

[0031] Each pixel 221 is a modulation element including a fixed member 222 and a movable member 223. The fixed member 222 is a planar, substantially rectangular member fixed to the substrate, and has a substantially circular opening in its center. The movable member 223 is a substantially circular member provided in the opening of the fixed member 222. A fixed reflective surface is provided on the upper surface of the fixed member 222 (i.e., the surface on the near side in the direction perpendicular to the paper surface in FIG. 2 ). A movable reflective surface is provided on the upper surface of the movable member 223. The movable member 223 is movable in the direction perpendicular to the paper surface in FIG. 2 .

[0032] In each pixel 221, the relative position of the fixed member 222 and the movable member 223 in the direction perpendicular to the paper surface in FIG. 2 is changed, thereby switching the reflected light from the pixel 221 between zeroth-order light (i.e., specularly reflected light) and non-zeroth-order diffracted light. In other words, in the pixel 221, the movable member 223 moves relative to the fixed member 222, thereby performing light modulation using a diffraction grating. The zeroth-order light generated by the optical modulator 22 is guided to the scanned surface 92 of the modeling material 91 by the second optical system 23 (see FIG. 1). The non-zeroth-order diffracted light generated by the optical modulator 22 is blocked by the second optical system 23 and does not reach the scanned surface 92 of the modeling material 91. The non-zeroth-order diffracted light is mainly first-order diffracted light (i.e., (+1)-order diffracted light and (−1)-order diffracted light), but also includes second-order or higher diffracted light.

[0033] In the optical modulator 22, the diffraction state of reflected light from M pixels 221 arranged in a vertical row in FIG. 2 (hereinafter also referred to as a "pixel column") is the same. That is, when the reflected light from one pixel 221 is zeroth-order light, the reflected light from all other pixels 221 in the pixel column including that pixel 221 (i.e., M-1 pixels 221) is also zeroth-order light. Furthermore, when the reflected light from one pixel 221 is non-zeroth-order diffracted light, the reflected light from all other pixels 221 in the pixel column including that pixel 221 is also non-zeroth-order diffracted light. That is, in the optical modulator 22, modulation is not performed in the minor axis direction of the shaped beam L32, but is performed in the major axis direction.

[0034] In the second optical system 23, for N pixel rows arranged in a row in the long axis direction of the shaped beam L32 on the optical modulator 22, reflected light from M pixels 221 included in each pixel row is integrated and directed to the scanned surface 92 of the modeling material 91, and N spot lights arranged in the long axis direction (i.e., a spot light array extending in the long axis direction) are formed on the scanned surface 92. This makes it possible to increase the power density of each spot light in the spot light array.

[0035] In the optical modulator 22, M pixels 221 (i.e., M modulation elements) in one pixel row can also be considered as one modulation element corresponding to one unit space. The optical modulator 22 functions as an optical modulator having N modulation elements arranged in a row in the direction of the major axis of the shaped beam L32 on the optical modulator 22.

[0036] The material supply mechanism 14 shown in FIG. 1 includes a modeling unit 141 and a supply unit 142. The modeling unit 141 includes a first cylinder 143 and a first piston 144. The first cylinder 143 is a cylindrical member extending in the vertical direction. The internal space of the first cylinder 143 has, for example, a substantially rectangular shape in a plan view. The first piston 144 is a substantially flat or columnar member housed in the internal space of the first cylinder 143, and its shape in a plan view is substantially the same as that of the internal space of the first cylinder 143. The first piston 144 is movable in the vertical direction within the internal space of the first cylinder 143. In the modeling unit 141, a three-dimensional space surrounded by the inner surface of the first cylinder 143 and the upper surface of the first piston 144 becomes a modeling space 140 where three-dimensional modeling using the modulated beam L33 is performed.

[0037] The supply unit 142 includes a second cylinder 145, a second piston 146, and a squeegee 147. The second cylinder 145 is a cylindrical member extending in the vertical direction and is disposed adjacent to the side of the first cylinder 143. The internal space of the second cylinder 145 has, for example, a substantially rectangular shape in a plan view. The second piston 146 is a substantially flat or columnar member housed in the internal space of the second cylinder 145 and has a shape substantially the same as that of the internal space of the second cylinder 145 in a plan view. The second piston 146 is movable in the vertical direction within the internal space of the second cylinder 145. In the supply unit 142, a three-dimensional space surrounded by the inner surface of the second cylinder 145 and the upper surface of the second piston 146 serves as a storage space in which the modeling material 91 to be supplied to the modeling unit 141 is stored. The squeegee 147 is a rod-shaped (for example, substantially cylindrical) member that extends horizontally across the upper opening of the second cylinder 145. The squeegee 147 is movable horizontally along the upper end surface of the second cylinder 145.

[0038] In the supply unit 142, the second piston 146 rises a predetermined distance, lifting the modeling material 91 in the second cylinder 145 upward. Then, the squeegee 147 moves from above the second cylinder 145 to above the first cylinder 143, whereby the modeling material 91 protruding above the upper end surface of the second cylinder 145 is supplied to and held in the modeling space 140 of the modeling unit 141. The modeling unit 141 is a material holding unit that holds the modeling material 91, which is an object to be irradiated with the modulated beam L33 from the optical device 12. The scanned surface 92, which is the upper surface of the modeling material 91 held in the modeling space 140, is located at a predetermined height (for example, the same height as the upper end surface of the first cylinder 143).

[0039] In the three-dimensional printing apparatus 1, the printing material 91 in the printing space 140 is scanned with the spot light array formed by the modulated beam L33. As a result, the surface portion of the printing material 91 in the printing space 140 that is irradiated with the modulated beam L33 is sintered, forming a portion that corresponds to one layer when the three-dimensional object is divided into multiple layers stacked in the vertical direction. When the scanning of the printing material 91 in the printing space 140 with the spot light array is completed, the first piston 144 descends a predetermined distance. Thereafter, as described above, the printing material 91 is supplied from the supply unit 142 to the printing space 140, and scanning with the spot light array is performed. In the three-dimensional printing apparatus 1, the supply of the printing material 91 to the printing space 140 and the scanning of the printing material 91 in the printing space 140 with the spot light array are repeated, thereby forming a three-dimensional object in the printing space 140.

[0040] Next, the detailed structure of the optical device 12 will be described with reference to FIGS. 3 and 4. FIGS. 3 and 4 are diagrams schematically showing the optical paths of the laser light L31, the shaped beam L32, and the modulated beam L33 in the optical device 12. In the optical device 12 illustrated in FIG. 1, the first optical system 21 and the second optical system 23 are disposed obliquely (i.e., so that the optical axis of the first optical system 21 intersects with the optical axis of the second optical system 23). However, in FIGS. 3 and 4, for ease of understanding, the positions of the first optical system 21 and the second optical system 23 are changed so that the optical axis of the first optical system 21 and the optical axis of the second optical system 23 are aligned. The same applies to FIGS. 7 and 8, which will be described later.

[0041] In Fig. 3, the optical paths of the shaped beam L32 and the modulated beam L33 are shown so that the minor axis directions of the shaped beam L32 and the modulated beam L33 coincide with the direction perpendicular to the paper surface. In Fig. 3, the major axis directions of the shaped beam L32 and the modulated beam L33 coincide with the up-and-down direction in the figure. In Fig. 4, the optical paths of the shaped beam L32 and the modulated beam L33 are shown so that the major axis directions of the shaped beam L32 and the modulated beam L33 coincide with the direction perpendicular to the paper surface. In Fig. 4, the minor axis directions of the shaped beam L32 and the modulated beam L33 coincide with the up-and-down direction in the figure. The same applies to Figs. 7 and 8, which will be described later.

[0042] The first optical system 21 of the optical device 12 includes a collimating lens 211, a beam shaper 213, and a beam expander 216. The collimating lens 211, the beam shaper 213, and the beam expander 216 are arranged in this order in the optical axis direction from the laser light source 11 to the optical modulator 22. The collimating lens 211 generates parallel light from the laser light L31. The lens shape of the collimating lens 211 may be spherical, aspherical, or cylindrical. Note that although the collimating lens 211 is composed of a single lens in the examples shown in FIGS. 3 and 4 , it may also be composed of multiple lenses.

[0043] The beam shaper 213 is a top-hat beam shaper that converts the distribution of light intensity in the major and minor axis directions in the cross section of a Gaussian-distributed collimated beam incident on the beam shaper 213 (hereinafter simply referred to as "intensity distribution") from a Gaussian distribution to a top-hat distribution in which the width of the maximum intensity region is wide (i.e., the top is approximately flat). The beam shaper 213 is, for example, a single optical element. In this embodiment, the beam shaper 213 is an aspherical concave lens. Note that various optical elements other than an aspherical concave lens (for example, a refractive optical element such as a freeform lens, or a diffractive optical element (DOE)) may also be used as the beam shaper 213.

[0044] The beam expander 216 expands the rectangular image generated by passing through the beam shaper 213 by different magnifications in the directions of the major axis and the minor axis, and forms an image on the modulation surface of the optical modulator 22. The beam expander 216 includes a cylinder lens 214a and a cylinder lens 214b for expanding the rectangular image in the direction of the major axis. The beam expander 216 also includes a cylinder lens 215a and a cylinder lens 215b for expanding the rectangular image in the direction of the minor axis. In the example shown in FIGS. 3 and 4 , the cylinder lens 214a, the cylinder lens 215a, the cylinder lens 214b, and the cylinder lens 215b are arranged in this order in the direction of the optical axis from the laser light source 11 to the optical modulator 22.

[0045] Note that optical elements other than those described above may be added to the first optical system 21. The configuration of the beam expander 216 may be modified in various ways. The first optical system 21 does not necessarily need to include the beam expander 216, and for example, a beam shaper 213 that directly forms a rectangular image of a desired size on the modulation surface of the optical modulator 22 may be used.

[0046] As described above, the first optical system 21 converts the laser light L31 emitted from the laser light source 11 into a collimated beam and guides it to the optical modulator 22. The intensity distributions in the major axis direction and the minor axis direction in the cross section of the laser light L31 incident on the first optical system 21 are each Gaussian distributions. In reality, these intensity distributions may not be strict Gaussian distributions but may be distributions with shapes that approximate Gaussian functions. In the following description, however, strict Gaussian distributions and distributions that approximate Gaussian distributions will be collectively referred to as "Gaussian distributions."

[0047] In the first optical system 21, the laser light L31 emitted from the laser light source 11 passes through the collimator lens 211 to become a collimated beam that is parallel light in the major axis direction and the minor axis direction. The collimated beam passes through the beam shaper 213 and the beam expander 216 and is guided to the optical modulator 22. The intensity distribution of the collimated beam before entering the beam shaper 213 is a Gaussian distribution in the major axis direction and also a Gaussian distribution in the minor axis direction, as shown by the rectangular frames at the bottom of the optical path diagrams in Figures 3 and 4.

[0048] By passing through the beam shaper 213, the intensity distribution of the collimated beam in the major axis direction and the minor axis direction is converted from a Gaussian distribution to a top-hat distribution (also called a rectangular distribution), as shown by the rectangular frames at the bottom of the optical path diagrams in Figures 3 and 4. Furthermore, the intensity distribution of the collimated beam in the major axis direction and the minor axis direction is maintained as a top-hat distribution when passing through the beam expander 216. Therefore, the intensity distribution of the shaped beam L32 that passes through the first optical system 21 and enters the optical modulator 22 (i.e., the intensity distribution of the shaped beam L32 on the modulation surface of the optical modulator 22) is a top-hat distribution in each of the major axis direction and the minor axis direction.

[0049] The second optical system 23 includes a first lens 231, a second lens 232, a third lens 233, a fourth lens 234, a major axis side light shielding portion 235, a minor axis side light shielding portion 236, and a scanning mechanism 237. The first lens 231 and the second lens 232 are, for example, cylindrical convex lenses. The third lens 233 and the fourth lens 234 are, for example, spherical convex lenses. The major axis side light shielding portion 235 is, for example, a flat plate member having a rectangular opening 2350 extending parallel to the minor axis direction at its center. The minor axis side light shielding portion 236 is, for example, a flat plate member having a rectangular opening 2360 extending parallel to the major axis direction at its center. The major axis side light shielding portion 235 and the minor axis side light shielding portion 236 are made of, for example, a metal such as stainless steel or ceramics.

[0050] In the present embodiment, the scanning mechanism 237 is a galvanometer scanner. The scanning mechanism 237 includes a first galvanometer mirror 371, a second galvanometer mirror 372, a first galvanometer motor (not shown), and a second galvanometer motor (not shown). The first galvanometer motor rotates the first galvanometer mirror 371 to change the reflection direction of the modulated beam L33 by the first galvanometer mirror 371. The second galvanometer motor rotates the second galvanometer mirror 372 to change the reflection direction of the modulated beam L33 by the second galvanometer mirror 372.

[0051] The second lens 232 and the third lens 233 are located on the scanned surface 92 side of the first lens 231 in the optical axis direction (i.e., the opposite side from the light modulator 22). In other words, the second lens 232 and the third lens 233 are located closer to the scanned surface 92 on the optical axis than the first lens 231. In the example shown in FIGS. 3 and 4 , the third lens 233 is located on the scanned surface 92 side of the second lens 232 in the optical axis direction (i.e., the opposite side from the first lens 231). In other words, the second lens 232 is located between the first lens 231 and the third lens 233. Note that the third lens 233 may be disposed between the first lens 231 and the second lens 232. The fourth lens 234 is located on the scanned surface 92 side of the first lens 231, the second lens 232, and the third lens 233 in the optical axis direction. In other words, the fourth lens 234 is located closer to the scanned surface 92 on the optical axis than the first lens 231, the second lens 232, and the third lens 233.

[0052] In the second optical system 23 illustrated in Figures 3 and 4, the first lens 231, the short axis side light shielding portion 236, the second lens 232, the third lens 233, the long axis side light shielding portion 235 and the fourth lens 234 are arranged in this order on the optical axis from the optical modulator 22 toward the scanned surface 92.

[0053] The minor axis side light shielding portion 236 is disposed near the focusing position on the minor axis side of the modulated beam L33 between the first lens 231 and the second and third lenses 232 and 233. Specifically, the minor axis side light shielding portion 236 is disposed near the focusing position on the minor axis side of the modulated beam L33 between the first lens 231 and the second lens 232 and the third lens 233. １ When the first-order diffraction angle from the optical modulator 22 in the minor axis direction is θ1 and the angle (NA) of the light incident on the minor axis side light shielding portion 236 and collected is θ2, the distance from the light collecting position on the optical axis (f １ / 2)×(tan θ1 / tan θ2), and more preferably on the light-condensing position. The minor-axis side light-shielding portion 236 is disposed, for example, at the rear focal position on the minor axis side of the first lens 231.

[0054] The long-axis side light-shielding portion 235 is disposed between the third lens 233 and the fourth lens 234, near the focusing position on the long-axis side of the modulated beam L33. Specifically, the long-axis side light-shielding portion 235 is disposed between the third lens 233 and the fourth lens 234, and the focal length of the third lens 233 is set to f ３ When the first-order diffraction angle from the optical modulator 22 in the long axis direction is θ3 and the angle (NA) of the light incident on the long axis side light shielding portion 235 and focused is θ4, the focused position (f ３ The long axis side light blocking portion 235 is preferably disposed within a range of (tan θ3 / tan θ4)×(tan θ3 / tan θ4), and more preferably disposed on the light collecting position. The position where the long axis side light blocking portion 235 is disposed is, for example, near the rear focal position of the third lens 233.

[0055] In the second optical system 23, a scanning mechanism 237 is also disposed on the optical axis between the third lens 233 and the fourth lens 234. The scanning mechanism 237 is disposed adjacent to the long axis side light shielding portion 235 and in the vicinity of the long axis side light shielding portion 235. In the optical axis direction, the distance between the scanning mechanism 237 and the long axis side light shielding portion 235 is smaller than the distance between the scanning mechanism 237 and the third lens 233 and the distance between the scanning mechanism 237 and the fourth lens 234.

[0056] Specifically, the first galvanometer mirror 371 of the scanning mechanism 237 is disposed on the optical modulator 22 side of the long axis side light shielding unit 235 in the optical axis direction. In other words, the first galvanometer mirror 371 is disposed on the optical axis between the second lens 232 and the third lens 233 and the long axis side light shielding unit 235. In the optical axis direction, the distance between the first galvanometer mirror 371 and the long axis side light shielding unit 235 is smaller than the distance between the first galvanometer mirror 371 and the third lens 233 and the distance between the first galvanometer mirror 371 and the second lens 232. The second galvanometer mirror 372 is disposed on the scanned surface 92 side of the long axis side light shielding unit 235 in the optical axis direction. In other words, the second galvanometer mirror 372 is disposed on the optical axis between the long axis side light shielding unit 235 and the fourth lens 234. In the optical axis direction, the distance between the second galvanometer mirror 372 and the major axis side light shielding portion 235 is smaller than the distance between the second galvanometer mirror 372 and the fourth lens 234 .

[0057] The first galvanometer mirror 371 and the second galvanometer mirror 372 are each disposed adjacent to the major axis side light-shielding portion 235 and in the vicinity of the major axis side light-shielding portion 235. The distance between the first galvanometer mirror 371 and the major axis side light-shielding portion 235 in the optical axis direction is, for example, 10 mm to 20 mm. The distance between the major axis side light-shielding portion 235 and the second galvanometer mirror 372 in the optical axis direction is, for example, 10 mm to 20 mm. The distance between the first galvanometer mirror 371 and the major axis side light-shielding portion 235 in the optical axis direction and the distance between the major axis side light-shielding portion 235 and the second galvanometer mirror 372 in the optical axis direction may be different, but are preferably approximately the same.

[0058] 3 and 4, it is preferable that no optical elements other than those shown are provided. For example, no optical elements other than the long axis side light shielding portion 235 and the scanning mechanism 237 are arranged between the third lens 233 and the fourth lens 234 on the optical axis. Naturally, no other optical elements are arranged between the third lens 233 and the first galvanometer mirror 371, and between the first galvanometer mirror 371 and the long axis side light shielding portion 235. Therefore, the modulated beam L33 passing through the third lens 233 is directly incident on the first galvanometer mirror 371 (i.e., without passing through other optical elements), and the modulated beam L33 reflected by the first galvanometer mirror 371 is directly incident on the long axis side light shielding portion 235 (i.e., without passing through other optical elements).

[0059] Furthermore, no other optical elements are arranged between the long axis side light shielding portion 235 and the second galvanometer mirror 372, and between the second galvanometer mirror 372 and the fourth lens 234. Therefore, the modulated beam L33 that passes through the long axis side light shielding portion 235 is directly incident on the second galvanometer mirror 372 (i.e., without passing through other optical elements), and the modulated beam L33 that is reflected by the second galvanometer mirror 372 is directly incident on the fourth lens 234 (i.e., without passing through other optical elements).

[0060] In addition, when the third lens 233 is placed between the first lens 231 and the second lens 232, it is preferable that no optical elements other than the long axis side shading portion 235 and the scanning mechanism 237 are placed between the second lens 232 and the fourth lens 234 on the optical axis.

[0061] In the second optical system 23, it is preferable that the front focal position on the short axis side of the first lens 231 (i.e., the focal position on the optical modulator 22 side) coincides with the modulation surface of the optical modulator 22. In this way, by setting the distance between the optical modulator 22 and the first lens 231 to be equal to or less than the front focal length of the first lens 231 (preferably less than this front focal length), the distance between the focal points of the zeroth-order diffracted light and the first-order diffracted light generated after passing through the first lens 231 increases. As a result, it is possible to easily separate the zeroth-order diffracted light from non-zeroth-order diffracted light such as the first-order diffracted light.

[0062] In the second optical system 23, the front focal position of the third lens 233 coincides with the modulation surface of the optical modulator 22. The rear focal position on the short axis side of the first lens 231 (i.e., the focal position on the scanned surface 92 side) coincides with the front composite focal position on the short axis side of the second lens 232 and the third lens 233. The rear focal position of the third lens 233 coincides with the front focal position of the fourth lens 234. The rear focal position of the fourth lens 234 coincides with the scanned surface 92 of the modeling material 91.

[0063] In the second optical system 23, the third lens 233 and the fourth lens 234 make the modulation surface of the optical modulator 22 and the scanned surface 92 of the modeling material 91 optically conjugate in the major axis direction. Additionally, the first lens 231, the second lens 232, and the third lens 233 make the modulation surface of the optical modulator 22 and the front focal position of the fourth lens 234 optically conjugate in the minor axis direction. The fourth lens 234 focuses the modulated beam L33 on the scanned surface 92 in the minor axis direction. The second lens 232, the third lens 233, and the fourth lens 234 make the scanned surface 92 optically conjugate with the rear focal position of the first lens 231 in the minor axis direction. In other words, the second lens 232, the third lens 233, and the fourth lens 234 make the minor axis side light shielding portion 236 and the scanned surface 92 optically conjugate in the minor axis direction.

[0064] In the second optical system 23, the types of the first lens 231, the second lens 232, the third lens 233, and the fourth lens 234 may be variously changed, and optical elements other than those described above may be added. In addition, the material, shape, and structure of the long axis side light shielding portion 235 and the short axis side light shielding portion 236 may also be variously changed.

[0065] As described above, the second optical system 23 guides the modulated beam L33 from the optical modulator 22 to the scanned surface 92 of the forming material 91, forms a spot light array on the scanned surface 92, and scans the spot light array on the scanned surface 92.

[0066] Specifically, the modulated beam L33, which is parallel light generated by the optical modulator 22, passes through the first lens 231 and is thereby condensed in the short axis direction at the rear focal position of the first lens 231 (i.e., the front composite focal position of the second lens 232 and the third lens 233). The modulated beam L33 is not refracted in the long axis direction when passing through the first lens 231.

[0067] The modulated beam L33 that has passed through the first lens 231 passes through an opening 2360 of the minor axis side light shielding portion 236 that is located at the rear focal position on the minor axis side of the first lens 231. Specifically, of the light reflected by the optical modulator 22, the zeroth order light and the non-zeroth order diffracted light on the major axis side pass through the rectangular opening 2360 of the minor axis side light shielding portion 236. Furthermore, of the light reflected by the optical modulator 22, the non-zero order diffracted light on the minor axis side (mainly the first order diffracted light) is blocked by the minor axis side light shielding portion 236. As shown in FIG. 5 , the non-zero order diffracted light on the minor axis side is irradiated onto a substantially linear irradiation region 81 extending in the major axis direction at locations above and below the opening 2360 of the minor axis side light shielding portion 236 (i.e., on both sides of the opening 2360 in the minor axis direction).

[0068] The cross section of the modulated beam L33 that has passed through the opening 2360 of the minor axis side light shielding portion 236 widens in the minor axis direction as it moves away from the minor axis side light shielding portion 236 in the optical axis direction. The modulated beam L33 that has passed through the minor axis side light shielding portion 236 becomes parallel light in the minor axis direction by passing through the second lens 232, and does not refract when passing through the third lens 233. Note that the modulated beam L33 that has passed through the minor axis side light shielding portion 236 may be refracted in the minor axis direction when passing through each of the second lens 232 and the third lens 233, and thereby become parallel light when passing through the third lens 233. The modulated beam L33 does not refract when passing through the second lens 232 in the major axis direction, and is focused at the rear focal position of the third lens 233 (i.e., the front focal position of the fourth lens 234) by passing through the third lens 233.

[0069] The modulated beam L33 that passes through the second lens 232 and the third lens 233 is incident on the first galvanometer mirror 371 of the scanning mechanism 237. Specifically, the zeroth-order light of the modulated beam L33 is incident on the first galvanometer mirror 371, while the non-zeroth-order diffracted light (mainly first-order diffracted light) on the major axis side is not incident on the first galvanometer mirror 371. The zeroth-order light of the modulated beam L33 reflected by the first galvanometer mirror 371 passes through the opening 2350 of the major axis side light shielding unit 235. In the scanning mechanism 237, the first galvanometer mirror 371 is rotated by the first galvanometer motor, thereby changing the reflection direction of the zeroth-order light in the minor axis direction by the first galvanometer mirror 371. As a result, the position in the minor axis direction of the zeroth-order light that passes through the opening 2350 is changed in the major axis side light shielding unit 235 that is arranged at the focusing position on the major axis side of the modulated beam L33.

[0070] On the other hand, the non-zeroth order diffracted light on the major axis side of the modulated beam L33 does not enter the first galvanometer mirror 371 as described above, but directly enters and is blocked by the major axis side light shielding portion 235. As shown in Fig. 6 , the non-zero order diffracted light on the major axis side is irradiated onto a substantially linear irradiation region 82 extending in the minor axis direction at positions to the left and right of the opening 2350 of the major axis side light shielding portion 235 in the drawing (i.e., on both sides of the opening 2350 in the major axis direction).

[0071] The cross section of the modulated beam L33 (i.e., zero-order light) that has passed through the opening 2350 of the major axis side light shielding portion 235 widens in the major axis direction as it moves away from the major axis side light shielding portion 235 in the optical axis direction. The modulated beam L33 that has passed through the opening 2350 of the major axis side light shielding portion 235 is incident on the second galvanometer mirror 372 of the scanning mechanism 237. The modulated beam L33 reflected by the second galvanometer mirror 372 is incident on the fourth lens 234. In the scanning mechanism 237, the second galvanometer mirror 372 is rotated by the second galvanometer motor, thereby changing the reflection direction of the modulated beam L33 by the second galvanometer mirror 372 in the major axis direction. This changes the position of the modulated beam L33 that is incident on the fourth lens 234 in the major axis direction.

[0072] The modulated beam L33 passes through the fourth lens 234, becoming parallel light in the long axis direction and incident on the scanned surface 92 of the modeling material 91. The modulated beam L33, which has entered the fourth lens 234 as parallel light in the short axis direction, passes through the fourth lens 234 and is thereby focused in the short axis direction on the scanned surface 92 located at the rear focal position of the fourth lens 234.

[0073] As described above, the modulation surface of the optical modulator 22 and the scanned surface 92 of the modeling material 91 are optically conjugate in the long axis direction. Furthermore, the intensity distribution of the collimated beam in the long axis direction on the modulation surface of the optical modulator 22 is a top-hat distribution, as shown in the rectangular frame in FIG. 3 . Therefore, the intensity distribution of the modulated beam L33 in the long axis direction on the scanned surface 92 is also a top-hat distribution. In other words, the intensity distribution in the long axis direction of the spot light array formed on the scanned surface 92 by the modulated beam L33 is a top-hat distribution.

[0074] In addition, the modulation surface of the optical modulator 22 and the front focal position of the fourth lens 234 (i.e., the rear focal position of the third lens 233) are optically conjugate in the minor axis direction. Furthermore, the intensity distribution in the minor axis direction of the collimated beam on the modulation surface of the optical modulator 22 is converted into a top-hat distribution by the beam shaper 213, as shown in the rectangular frame in Fig. 4. Therefore, the intensity distribution in the minor axis direction of the modulated beam L33 that has passed through the third lens 233 becomes a top-hat distribution at the front focal position of the fourth lens 234.

[0075] Therefore, due to the Fourier transform effect of the fourth lens 234, the intensity distribution in the minor axis direction of the modulated beam L33 at the focal point (i.e., the above-mentioned spot light array) on the scanned surface 92 of the modeling material 91 becomes a distribution obtained by squaring a sinc function. In reality, the intensity distribution in the minor axis direction of the modulated beam L33 may not be a strict distribution obtained by squaring a sinc function, but may be a distribution approximating the square of a sinc function. In the following description, the distribution obtained by squaring a strict sinc function and the distribution approximating the distribution obtained by squaring a sinc function are collectively referred to as the "squared distribution of a sinc function." The squared distribution of a sinc function has a main peak, similar to a Gaussian distribution, and therefore the modulated beam L33 can be suitably focused on the scanned surface 92.

[0076] In the three-dimensional printing apparatus 1, the first galvanometer mirror 371 of the scanning mechanism 237 of the optical device 12 rotates, causing the spot light array to scan the scanned surface 92 of the printing material 91 in a direction corresponding to the short axis direction (i.e., a direction perpendicular to the arrangement direction of the plurality of spot lights in the spot light array). Furthermore, the second galvanometer mirror 372 of the scanning mechanism 237 rotates, causing the spot light array to scan the scanned surface 92 of the printing material 91 in a direction corresponding to the long axis direction (i.e., a direction parallel to the arrangement direction of the plurality of spot lights in the spot light array). In the three-dimensional printing apparatus 1, a three-dimensional object is formed by repeatedly scanning the printing material 91 with the spot light array and supplying the printing material 91 to the printing space 140.

[0077] The size of the modulated beam L33 on the scanned surface 92 of the modeling material 91 can be calculated as follows: For example, the wavelength λ of the laser light L31 is 1.070 μm, and the irradiation area on the modulation surface of the optical modulator 22 has a length L in the major axis direction. １ is 28 mm, and the length of the minor axis L ２ The focal length f of the first lens 231 and the second lens 232 on the minor axis side is approximately linear (or approximately rectangular). １ , f ２ are 40 mm and 400 mm, respectively, and the focal lengths f ３ , f ４ are 240 mm and 240 mm, respectively. The distance d between the second lens 232 and the third lens 233 is 50 mm. In this case, the combined focal length f ２３ is approximately 163 mm.

[0078] In the minor axis direction, as described above, the modulated beam L33 is focused at the rear focal position of the first lens 231 (i.e., the position where the minor axis side light blocking portion 236 is disposed). The focused width in the minor axis direction of the modulated beam L33 at the rear focal position of the first lens 231 (i.e., the first dark line width of the squared distribution of the sinc function) d Ｓ１ is 2.0 x λ x f １ / L ２ The rear focal position of the first lens 231 is optically conjugate with the scanned surface 92 of the modeling material 91 in the minor axis direction. Therefore, the focused diameter of the modulated beam L33 on the scanned surface 92 in the minor axis direction is 86 μm×f ４ / f ２３ ≒126 μm.

[0079] As described above, in the long axis direction, the modulated beam L33 is focused at the rear focal position of the third lens 233. The focused width in the long axis direction of the modulated beam L33 at the rear focal position of the third lens 233 (i.e., the width between the first dark lines of the squared distribution of the sinc function) d Ｌ３ is 2.0 x λ x f ３ / L １The length L of the modulated beam L33 in the minor axis direction at the rear focal position of the third lens 233 is approximately 18 μm. ３ Is, L ２ xf ２３ / f １ = 4 mm. In the long axis direction, the modulation surface of the optical modulator 22 and the scanned surface 92 of the modeling material 91 are optically conjugate. Therefore, the length of the modulated beam L33 in the long axis direction on the scanned surface 92 is L １ xf ４ / f ３ = 28 mm.

[0080] As described above, the minor axis side light shielding portion 236 is disposed at the rear focal position of the first lens 231. Therefore, the irradiation area 81 (see FIG. 5) of the first-order diffracted light (i.e., the (+1)-order diffracted light and the (−1)-order diffracted light) irradiated on both sides of the minor axis direction of the opening 2360 of the minor axis side light shielding portion 236 is such that the major axis direction is L １ = 28 mm, and the minor axis direction is d Ｓ１ In addition, since the long-axis side light-shielding portion 235 is disposed at the rear focal position of the third lens 233, the irradiation area 82 (see FIG. 6) of the first-order diffracted light irradiated on both sides of the long-axis direction of the opening 2350 of the long-axis side light-shielding portion 235 is approximately linear with a length of d Ｌ３ ≒18 μm, and the minor axis direction is L ３ = 4 mm, resulting in a substantially linear shape.

[0081] On the other hand, assuming an optical device (hereinafter referred to as the "comparative optical device") in which modulated beam L33 is focused by a single convex lens at the same position on the optical path (i.e., the rear focal position of the convex lens) in both the major axis direction and the minor axis direction, the first-order diffracted light is irradiated onto a point-like irradiation area on the light-shielding portion located at the rear focal position. For example, if the focal length of the convex lens is 240 mm, the diameter of the irradiation area of ​​the first-order diffracted light on the light-shielding portion will be approximately 326 μm.

[0082] Therefore, in the optical device 12 of this embodiment, the power density of first-order diffracted light on the short axis side shading portion 236 and the power density of first-order diffracted light on the long axis side shading portion 235 are reduced to 10% or less of the power density of first-order diffracted light on the shading portions of the optical device of the comparative example.

[0083] The sizes of the first galvanometer mirror 371 and the second galvanometer mirror 372 are changed depending on the positions of the first galvanometer mirror 371 and the second galvanometer mirror 372. For example, the first galvanometer mirror 371 is disposed 20 mm in front of the long-axis side light-shielding portion 235 (i.e., on the optical modulator 22 side in the optical axis direction), and the second galvanometer mirror 372 is disposed 20 mm behind the long-axis side light-shielding portion 235 (i.e., on the scanned surface 92 side in the optical axis direction). In this case, as described above, the irradiation area of ​​the modulated beam L33 on the major axis side light-shielding portion 235 is approximately linear with a major axis direction of 22 μm and a minor axis direction of 4 mm, and the NA forming the modulated beam L33 is approximately 0.058 on the major axis side and approximately 0 on the minor axis side, so the irradiation area of ​​the modulated beam L33 on the first galvanometer mirror 371 and the second galvanometer mirror 372 is approximately rectangular with a major axis direction of approximately 2.3 mm and a minor axis direction of approximately 4 mm. Therefore, the size of the first galvanometer mirror 371 and the second galvanometer mirror 372 is set to be large enough to accommodate the irradiation area or larger.

[0084] Next, an optical device 12a according to a second embodiment of the present invention will be described with reference to Figures 7 and 8. Figures 7 and 8 are diagrams schematically showing the optical paths of the laser light L31, the shaped beam L32, and the modulated beam L33 in the optical device 12a, and correspond to Figures 3 and 4 described above.

[0085] 7 and 8, the optical device 12a is provided with a first optical system 21a and a second optical system 23a having configurations different from those of the first optical system 21 and the second optical system 23, instead of the first optical system 21 and the second optical system 23 shown in FIGS. 3 and 4. Specifically, the first optical system 21a includes an illumination optical element 216a instead of the beam expander 216 (i.e., the cylinder lens 214a, the cylinder lens 215a, the cylinder lens 214b, and the cylinder lens 215b) shown in FIGS. 3 and 4. The second optical system 23a includes a first lens 231a, a second lens 232a, and a third lens 233a instead of the first lens 231, the second lens 232, the third lens 233, and the fourth lens 234 shown in FIGS. 3 and 4. The other configurations of the optical device 12a are substantially similar to those of the optical device 12, and in the following description, the same reference numerals as those of the corresponding configurations of the optical device 12 will be used.

[0086] Similar to the first optical system 21 described above, the first optical system 21a shapes the laser light L31 emitted from the laser light source 11 into a substantially rectangular shaped beam L32 that is long in the major axis direction and guides the beam to the optical modulator 22. In the first optical system 21a, a collimator lens 211, a beam shaper 213, and an illumination optical element 216a are arranged in this order in the traveling direction of the light from the laser light source 11 to the optical modulator 22 (i.e., the optical axis direction). The illumination optical element 216a is, for example, a single lens, and in the examples shown in FIGS. 7 and 8, is a single spherical convex lens. The illumination optical element 216a may also be an aspherical convex lens. Alternatively, the illumination optical element 216a may be composed of multiple optical elements.

[0087] 7 and 8, no optical element other than the illumination optical element 216a, which is a single lens, is disposed between the beam shaper 213 and the optical modulator 22. In other words, the beam emitted from the beam shaper 213 is incident directly on the illumination optical element 216a (i.e., without passing through any other optical elements). Furthermore, the shaped beam L32 that has passed through the illumination optical element 216a is incident directly on the optical modulator 22 (i.e., without passing through any other optical elements).

[0088] In the first optical system 21a, similarly to the first optical system 21, the laser light L31 emitted from the laser light source 11 passes through the collimating lens 211 to become a collimated beam that is parallel light in the major axis direction and the minor axis direction. The collimated beam passes through the beam shaper 213 and the illumination optical element 216a and is guided to the optical modulator 22. The intensity distribution of the collimated beam before entering the beam shaper 213 is a Gaussian distribution in the major axis direction and also a Gaussian distribution in the minor axis direction, as shown by the rectangular frames at the bottom of the optical path diagrams in FIGS. 7 and 8 .

[0089] The beam shaper 213 expands the collimated beam (i.e., incident light) incident thereon at different divergence angles in the major axis direction and the minor axis direction. The intensity distribution of the collimated beam in the major axis direction and the minor axis direction is converted from a Gaussian distribution to a top-hat distribution (also called a rectangular distribution) by passing through the beam shaper 213. Furthermore, the intensity distribution of the collimated beam in the major axis direction and the minor axis direction is maintained as a top-hat distribution when passing through the illumination optical element 216a. Therefore, as shown by a rectangular frame at the bottom of the optical path diagrams in FIGS. 7 and 8 , the intensity distribution of the shaped beam L32 that passes through the first optical system 21a and enters the optical modulator 22 (i.e., the intensity distribution of the shaped beam L32 on the modulation surface of the optical modulator 22) is a top-hat distribution in both the major axis direction and the minor axis direction.

[0090] In the first optical system 21a, the collimated beam passes through the beam shaper 213 and the illumination optical element 216a, becoming a shaped beam L32 that is parallel light in the major axis direction and convergent light in the minor axis direction, and is incident on the modulation surface of the optical modulator 22. The condensing position in the minor axis direction of the shaped beam L32 by the illumination optical element 216a is located on the opposite side of the optical modulator 22 from the first optical system 21a (i.e., on the scanned surface 92 side of the optical modulator 22). Therefore, the shaped beam L32 is incident on the optical modulator 22 before reaching the condensing position on the minor axis side.

[0091] The shaped beam L32 incident on the optical modulator 22 is modulated by the optical modulator 22 and enters the second optical system 23a as a modulated beam L33. The modulated beam L33 incident on the second optical system 23a from the optical modulator 22 is a parallel light in the major axis direction and a convergent light in the minor axis direction. The optical modulator 22 is, for example, an LPLV.

[0092] The second optical system 23a is substantially similar to the above-described second optical system 23, and is an optical system in which a scanning mechanism 237 that scans the modulated beam L33 on the scanned surface 92 is incorporated inside a projection optical system that guides the modulated beam L33 from the optical modulator 22 to the scanned surface 92 of the building material 91. The second optical system 23a includes a first lens 231a, a second lens 232a, a third lens 233a, a long axis side light shielding portion 235, a short axis side light shielding portion 236, and the scanning mechanism 237.

[0093] The first lens 231a is, for example, a single lens, and in the example shown in Figures 7 and 8, it is a single spherical convex lens. The second lens 232a is, for example, a single lens, and in the example shown in Figures 7 and 8, it is a single spherical convex lens. The first lens 231a and the second lens 232a may each be an aspherical convex lens. The third lens 233a is, for example, a single lens, and in the example shown in Figures 7 and 8, it is a single cylindrical convex lens.

[0094] In the present embodiment, as in the above, the scanning mechanism 237 is a galvanometer scanner. In the scanning mechanism 237, a first galvanometer motor (not shown) rotates a first galvanometer mirror 371, thereby changing the reflection direction of the modulated beam L33 by the first galvanometer mirror 371. Furthermore, a second galvanometer motor (not shown) rotates a second galvanometer mirror 372, thereby changing the reflection direction of the modulated beam L33 by the second galvanometer mirror 372.

[0095] In the second optical system 23a illustrated in Figures 7 and 8, the short axis side shading portion 236, the third lens 233a, the first lens 231a, the long axis side shading portion 235 and the second lens 232a are arranged in this order on the optical axis extending from the optical modulator 22 toward the scanned surface 92.

[0096] The minor axis side light shielding portion 236 is disposed between the optical modulator 22 and the third lens 233a, in the same manner as in the second optical system 23 described above, near the focusing position on the minor axis side of the modulated beam L33. In the second optical system 23a illustrated in Figures 7 and 8, no other optical elements such as lenses are disposed between the optical modulator 22 and the minor axis side light shielding portion 236. In other words, the modulated beam L33 modulated by the optical modulator 22 is directly incident on the minor axis side light shielding portion 236 (i.e., without passing through other optical elements). Furthermore, the modulated beam L33 that passes through the opening 2360 of the minor axis side light shielding portion 236 is directly incident on the third lens 233 (i.e., without passing through other optical elements).

[0097] The long-axis side light-shielding portion 235 is disposed between the first lens 231a and the second lens 232a near the focusing position on the long axis side of the modulated beam L33, similar to the second optical system 23 described above. The position where the long-axis side light-shielding portion 235 is disposed is, for example, near the rear focal position of the first lens 231a. The rear focal position of the first lens 231a coincides with the front focal position of the second lens 232a.

[0098] In the second optical system 23a, a scanning mechanism 237 is disposed on the optical axis between the first lens 231a and the second lens 232a. Similar to the second optical system 23 described above, the scanning mechanism 237 is disposed adjacent to the long axis side light shielding portion 235 and in the vicinity of the long axis side light shielding portion 235. In the optical axis direction, the distance between the scanning mechanism 237 and the long axis side light shielding portion 235 is smaller than the distance between the scanning mechanism 237 and the first lens 231a and the distance between the scanning mechanism 237 and the second lens 232a.

[0099] Specifically, the first galvanometer mirror 371 of the scanning mechanism 237 is disposed on the optical modulator 22 side of the long axis side light shielding portion 235 in the optical axis direction. In other words, the first galvanometer mirror 371 is disposed on the optical axis between the first lens 231a and the long axis side light shielding portion 235. In the optical axis direction, the distance between the first galvanometer mirror 371 and the long axis side light shielding portion 235 is shorter than the distance between the first galvanometer mirror 371 and the first lens 231a. The second galvanometer mirror 372 is disposed on the scanned surface 92 side of the long axis side light shielding portion 235 in the optical axis direction. In other words, the second galvanometer mirror 372 is disposed on the optical axis between the long axis side light shielding portion 235 and the second lens 232a. In the optical axis direction, the distance between the second galvanometer mirror 372 and the long-axis side light-shielding portion 235 is shorter than the distance between the second galvanometer mirror 372 and the second lens 232 a. The positional relationship between the first galvanometer mirror 371, the second galvanometer mirror 372, and the long-axis side light-shielding portion 235, etc. is substantially the same as that in the second optical system 23 described above.

[0100] 7 and 8, it is preferable that no optical elements other than those shown are provided. For example, no optical elements other than the long axis side light shielding unit 235 and the scanning mechanism 237 are arranged between the first lens 231a and the second lens 232a on the optical axis. Naturally, no other optical elements are arranged between the first lens 231a and the first galvanometer mirror 371, and between the first galvanometer mirror 371 and the long axis side light shielding unit 235. Therefore, the modulated beam L33 passing through the first lens 231a is directly incident on the first galvanometer mirror 371 (i.e., without passing through other optical elements), and the modulated beam L33 reflected by the first galvanometer mirror 371 is directly incident on the long axis side light shielding unit 235 (i.e., without passing through other optical elements).

[0101] Furthermore, no other optical elements are disposed between the long-axis side light-shielding portion 235 and the second galvanometer mirror 372, and between the second galvanometer mirror 372 and the second lens 232a. Therefore, the modulated beam L33 that passes through the long-axis side light-shielding portion 235 is directly incident on the second galvanometer mirror 372 (i.e., without passing through other optical elements), and the modulated beam L33 that is reflected by the second galvanometer mirror 372 is directly incident on the second lens 232a (i.e., without passing through other optical elements).

[0102] In the second optical system 23a, the first lens 231a and the second lens 232a make the modulation surface of the optical modulator 22 and the scanned surface 92 of the modeling material 91 optically conjugate in the long axis direction. In addition, in the short axis direction, the third lens 233a, the first lens 231a, and the second lens 232a make the short axis side light blocking portion 236 and the scanned surface 92 optically conjugate. Note that in the second optical system 23a, the types of the first lens 231a, the second lens 232a, and the third lens 233a may be changed in various ways, and optical elements other than those described above may be added.

[0103] Similar to the second optical system 23, the second optical system 23a guides the modulated beam L33 from the optical modulator 22 to the scanned surface 92 of the forming material 91, forms a spot light array on the scanned surface 92, and scans the spot light array on the scanned surface 92.

[0104] Specifically, the modulated beam L33, which is a convergent light on the minor axis side, is focused on the minor axis side at the focusing position where the minor axis side light shielding portion 236 is disposed, and passes through the opening 2360 of the minor axis side light shielding portion 236. More specifically, of the modulated beam L33, which is reflected light reflected by the optical modulator 22, the zeroth order light and non-zeroth order diffracted light on the major axis side pass through the opening 2360 of the minor axis side light shielding portion 236. The cross-sectional shape of the modulated beam L33 passing through the opening 2360 of the minor axis side light shielding portion 236 is an approximately linear or approximately rectangular shape that is elongated in the major axis direction. The intensity distribution of the modulated beam L33 passing through the opening 2360 of the minor axis side light shielding portion 236 is an approximately top-hat distribution in the major axis direction and a squared distribution of a sinc function in the minor axis direction, as shown by the rectangular frames at the bottom of the optical path diagrams in FIGS. 7 and 8 .

[0105] On the other hand, of modulated beam L33, non-zero-order diffracted light on the minor axis side is blocked by minor axis side light shielding portion 236. The non-zero-order diffracted light on the minor axis side is irradiated onto a substantially linear or substantially rectangular irradiation region 81 that is long in the major axis direction, in areas above and below opening 2360 of minor axis side light shielding portion 236 shown in FIG.

[0106] As shown in Figures 7 and 8, the cross section of the modulated beam L33 that has passed through the opening 2360 of the minor axis side light shielding portion 236 widens in the minor axis direction as it moves away from the minor axis side light shielding portion 236 in the optical axis direction. The modulated beam L33 that has passed through the minor axis side light shielding portion 236 becomes parallel light in the minor axis direction by passing through the third lens 233a and the first lens 231a. For example, the modulated beam L33 that has passed through the minor axis side light shielding portion 236 becomes parallel light in the minor axis direction by passing through the third lens 233a, and is not refracted in the minor axis direction when passing through the first lens 231a. Furthermore, the modulated beam L33 is not refracted in the major axis direction when passing through the third lens 233a, but is converged by passing through the first lens 231a and collected at the rear focal position of the first lens 231a (i.e., the front focal position of the second lens 232a).

[0107] The modulated beam L33 that passes through the third lens 233a and the first lens 231a is incident on the first galvanometer mirror 371 of the scanning mechanism 237. Specifically, the zeroth-order light of the modulated beam L33 is incident on the first galvanometer mirror 371, while the non-zeroth-order diffracted light (mainly first-order diffracted light) on the major axis side is not incident on the first galvanometer mirror 371. The zeroth-order light of the modulated beam L33 reflected by the first galvanometer mirror 371 passes through the opening 2350 of the major axis side light shielding unit 235. In the scanning mechanism 237, the first galvanometer mirror 371 is rotated by the first galvanometer motor, thereby changing the reflection direction of the zeroth-order light by the first galvanometer mirror 371 in the minor axis direction. As a result, the position in the minor axis direction of the zeroth-order light that passes through the opening 2350 is changed in the major axis side light shielding unit 235 that is arranged at the focusing position on the major axis side of the modulated beam L33.

[0108] On the other hand, the non-zeroth order diffracted light on the major axis side of the modulated beam L33 does not enter the first galvanometer mirror 371 as described above, but directly enters and is blocked by the major axis side light shielding portion 235. The non-zero order diffracted light on the major axis side is irradiated onto a substantially linear irradiation region 82 extending in the minor axis direction at positions to the left and right of the opening 2350 of the major axis side light shielding portion 235 shown in FIG. 6 (i.e., on both sides of the opening 2350 in the major axis direction).

[0109] The cross-sectional shape of the modulated beam L33 passing through the opening 2350 of the major axis side light shielding portion 235 is a substantially linear or substantially rectangular shape that is long in the minor axis direction. The intensity distribution of the modulated beam L33 passing through the opening 2350 of the major axis side light shielding portion 235 is a square distribution of a sinc function in the major axis direction and a top-hat distribution in the minor axis direction, as shown by a rectangular frame at the bottom of the optical path diagrams in Figures 7 and 8.

[0110] The cross section of the modulated beam L33 (i.e., zero-order light) that has passed through the opening 2350 of the major axis side light shielding portion 235 widens in the major axis direction as it moves away from the major axis side light shielding portion 235 in the optical axis direction. The modulated beam L33 that has passed through the opening 2350 of the major axis side light shielding portion 235 is incident on the second galvanometer mirror 372 of the scanning mechanism 237. The modulated beam L33 reflected by the second galvanometer mirror 372 is incident on the second lens 232a. In the scanning mechanism 237, the second galvanometer mirror 372 is rotated by the second galvanometer motor, thereby changing the reflection direction of the modulated beam L33 by the second galvanometer mirror 372 in the major axis direction. This changes the position in the major axis direction of the modulated beam L33 that is incident on the second lens 232a.

[0111] The modulated beam L33 passes through the second lens 232a, becoming parallel light in the long axis direction and incident on the scanned surface 92 of the modeling material 91. The modulated beam L33, which has entered the second lens 232a as parallel light in the short axis direction, passes through the second lens 232a and is condensed in the short axis direction on the scanned surface 92 located at the rear focal position of the second lens 232a.

[0112] The cross-sectional shape of the modulated beam L33 on the scanned surface 92 of the building material 91 is a substantially rectangular shape that is long in the major axis direction. The intensity distribution of the modulated beam L33 on the scanned surface 92 is a top-hat distribution in the major axis direction and a squared distribution of a sinc function in the minor axis direction, as shown by the rectangular frame at the bottom of the optical path diagrams in Figures 7 and 8. In other words, the intensity distribution in the major axis direction and the intensity distribution in the minor axis direction of the spot light array formed on the scanned surface 92 by the modulated beam L33 are a top-hat distribution and a squared distribution of a sinc function, respectively. This allows the modulated beam L33 to be suitably focused on the scanned surface 92.

[0113] In the three-dimensional printing apparatus 1 provided with the optical device 12a, the first galvanometer mirror 371 of the scanning mechanism 237 of the optical device 12a rotates, causing the spot light array to scan the scanned surface 92 of the printing material 91 in a direction corresponding to the short axis direction (i.e., a direction perpendicular to the arrangement direction of the plurality of spot lights in the spot light array), in substantially the same manner as described above. Furthermore, the second galvanometer mirror 372 of the scanning mechanism 237 rotates, causing the spot light array to scan the scanned surface 92 of the printing material 91 in a direction corresponding to the long axis direction (i.e., a direction parallel to the arrangement direction of the plurality of spot lights in the spot light array). In the three-dimensional printing apparatus 1, a three-dimensional object is formed by repeatedly scanning the printing material 91 with the spot light array and supplying the printing material 91 to the printing space 140.

[0114] In the optical devices 12 and 12a described above, if the optical element arranged between the short-axis side light-shielding portion 236 and the scanned surface 92 of the building material 91 and converging the modulated beam L33 in the long-axis direction is referred to as the "first projection optical element," then the third lens 233 is the first projection optical element in the optical device 12, and the first lens 231a is the first projection optical element in the optical device 12a. Also, if the optical element arranged between the long-axis side light-shielding portion 235 and the scanned surface 92 and converging the modulated beam L33 that has passed through the long-axis side light-shielding portion 235 in the short-axis direction and converging it onto the scanned surface 92 is referred to as the "second projection optical element," then the fourth lens 234 is the second projection optical element in the optical device 12, and the second lens 232a is the second projection optical element in the optical device 12.

[0115] In the above-described optical device 12, 12a, the first galvanometer mirror 371 rotates to change the reflection direction of the modulated beam L33 in the minor axis direction, and the second galvanometer mirror 372 rotates to change the reflection direction of the modulated beam L33 in the major axis direction, but this is not limited to this. For example, the first galvanometer mirror 371 may rotate to change the reflection direction of the modulated beam L33 in the major axis direction, and the second galvanometer mirror 372 may rotate to change the reflection direction of the modulated beam L33 in the minor axis direction. That is, the first galvanometer mirror 371 rotates to change the reflection direction of the modulated beam L33 in one of the major axis and minor axis directions. Furthermore, the second galvanometer mirror 372 rotates to change the reflection direction of the modulated beam L33 in the other of the major axis and minor axis directions.

[0116] In the optical device 12, 12a described above, the first galvanometer mirror 371 is disposed between the first projection optical element (i.e., the third lens 233 / first lens 231a) and the long axis side light shielding portion 235, and the second galvanometer mirror 372 is disposed between the long axis side light shielding portion 235 and the second projection optical element (i.e., the fourth lens 234 / second lens 232a), but this is not limited thereto. For example, the first galvanometer mirror 371 and the second galvanometer mirror 372 may be disposed between the long axis side light shielding portion 235 and the second projection optical element. In this case, since there is no mechanism for changing the direction of the modulated beam L33 closer to the optical modulator 22 than the long axis side light shielding portion 235 in the optical axis direction, the opening 2350 of the long axis side light shielding portion 235 can be made smaller. Furthermore, since non-zero-order diffracted light on the major axis side does not enter the galvanometer mirror, the design of the scanning mechanism 237 and the major axis side light blocking portion 235 can be simplified.

[0117] Alternatively, the first galvanometer mirror 371 and the second galvanometer mirror 372 may be disposed between the above-described first projection optical element and the long-axis side light-shielding unit 235. In this manner, by disposing the first galvanometer mirror 371 and the second galvanometer mirror 372 on either side of the long-axis side light-shielding unit 235 in the optical axis direction, it is possible to reduce the distance in the optical axis direction between the first galvanometer mirror 371 and the second galvanometer mirror 372. As a result, it is possible to reduce the size of the second galvanometer mirror 372, which needs to receive the modulated beam L33 whose reflection direction has been changed by the first galvanometer mirror 371.

[0118] It is preferable that the arrangement of the first galvanometer mirror 371 and the second galvanometer mirror 372 is determined so that the shape of the irradiation area of ​​the modulated beam L33 on the scanned surface 92 of the forming material 91 is close to the desired shape, taking into consideration the distortion characteristics due to the arrangement and the distortion characteristics of the second projection optical element described above.

[0119] In the optical device 12, 12a, the scanning mechanism 237 may include only one of the first galvanometer mirror 371 and the second galvanometer mirror 372. The one galvanometer mirror may be disposed on the optical modulator 22 side of the long-axis side light-shielding portion 235 in the optical axis direction, or may be disposed on the scanned surface 92 side of the long-axis side light-shielding portion 235. Furthermore, the reflection direction of the modulated beam L33 changed by the rotation of the one galvanometer mirror may be in the long-axis direction or in the short-axis direction.

[0120] That is, when the one galvanometer mirror is disposed on the optical modulator 22 side of the long-axis side light-shielding portion 235 in the optical axis direction, the rotation of the one galvanometer mirror scans the modulated beam L33 in one of the long-axis direction and the short-axis direction before it enters the long-axis side light-shielding portion 235. Also, when the one galvanometer mirror is disposed on the scanned surface 92 side of the long-axis side light-shielding portion 235 in the optical axis direction, the rotation of the one galvanometer mirror scans the modulated beam L33 that has passed through the long-axis side light-shielding portion 235 in one of the long-axis direction and the short-axis direction. Scanning of the modulated beam L33 in the other of the long-axis direction and the short-axis direction is achieved by, for example, moving the modeling material 91 in the modeling space 140 in a direction corresponding to the other direction by a moving mechanism such as a linear motor provided in the material supply mechanism 14.

[0121] As described above, the optical device 12, 12a is a device that irradiates and scans an object (in the above example, the build material 91) with a spot light array. The optical device 12, 12a includes a first optical system 21, 21a, an optical modulator 22, and a second optical system 23, 23a. The first optical system 21, 21a shapes the laser light L31 into a shaped beam L32 that is long in the major axis direction. The optical modulator 22 modulates the shaped beam L32 to form a modulated beam L33 that has a pattern in the major axis direction. The second optical system 23, 23a guides the modulated beam L33 to a scanned surface 92 of the object to form a spot light array on the scanned surface 92 that extends in the major axis direction, and scans the scanned surface 92 with the spot light array.

[0122] The second optical system 23, 23a includes a short axis side shading portion 236, a first projection optical element (in the above example, the third lens 233 or the first lens 231a), a long axis side shading portion 235, a second projection optical element (in the above example, the fourth lens 234 or the second lens 232a), and a scanning mechanism 237.

[0123] The minor axis side light shielding portion 236 is disposed at a focusing position on the minor axis side of the modulated beam L33. The minor axis side light shielding portion 236 blocks non-zero order diffracted light on the minor axis side of the modulated beam L33. The first projection optical element is disposed between the minor axis side light shielding portion 236 and the scanned surface 92. The first projection optical element focuses the modulated beam L33 in the major axis direction. The major axis side light shielding portion 235 is disposed between the first projection optical element and the scanned surface 92 at a focusing position on the major axis side of the modulated beam L33 by the first projection optical element. The major axis side light shielding portion 235 blocks non-zero order diffracted light on the major axis side of the modulated beam L33. The second projection optical element is disposed between the major axis side light shielding portion 235 and the scanned surface 92. The second projection optical element forms a spot light array on the scanned surface 92 by converging the modulated beam L33 that has passed through the long axis side light shielding portion 235 in the short axis direction and focusing it on the scanned surface 92.

[0124] The scanning mechanism 237 is disposed adjacent to the long axis side light shielding portion 235 between the first projection optical element and the second projection optical element. The scanning mechanism 237 scans the modulated beam L33 incident on the long axis side light shielding portion 235 or the modulated beam L33 that has passed through the long axis side light shielding portion 235 in at least one of the long axis direction and the short axis direction. In the optical device 12, 12a, the second optical system 23, 23a makes the modulation surface of the optical modulator 22 and the scanned surface 92 optically conjugate in the long axis direction.

[0125] Thus, in the second optical system 23, 23a of the optical device 12, 12a, a scanning mechanism 237 that scans the spot light array on the scanned surface 92 is incorporated within a projection optical system that relays the modulated beam L33 from the optical modulator 22 to the target object and forms a spot light array on the scanned surface 92. Therefore, when the projection optical system and the scanning unit are provided separately, optical elements other than the scanning mechanism that are required in the scanning unit (e.g., collimating lenses and Fθ lenses provided before and after the galvano scanner in the scanning unit) can be omitted. As a result, the structure of the optical device 12, 12a can be simplified. Furthermore, the optical device 12, 12a can be made smaller. Furthermore, the manufacturing cost of the optical device 12, 12a can be reduced.

[0126] As described above, the scanning mechanism 237 is preferably a galvanometer scanner that changes the reflection direction of the modulated beam L33. This allows the scanning of the spot light array on the scanned surface 92 to be achieved with a simple structure. As a result, the structure of the optical device 12, 12a can be further simplified.

[0127] As described above, the galvanometer scanner preferably includes a first galvanometer mirror 371 and a second galvanometer mirror 372. The first galvanometer mirror 371 is preferably disposed adjacent to the long-axis side light-shielding portion 235 between the first projection optical element and the long-axis side light-shielding portion 235. The first galvanometer mirror 371 changes the reflection direction of the modulated beam L33 in one of the long-axis and short-axis directions by rotating. The second galvanometer mirror 372 is preferably disposed adjacent to the long-axis side light-shielding portion 235 between the long-axis side light-shielding portion 235 and the second projection optical element. The second galvanometer mirror 372 changes the reflection direction of the modulated beam L33 in the other of the long-axis and short-axis directions by rotating.

[0128] In this way, by arranging the first galvanometer mirror 371 and the second galvanometer mirror 372 on both the front and rear sides of the major axis side light shielding portion 235 in the optical axis direction, the distance between the first projection optical element and the major axis side light shielding portion 235 and the distance between the major axis side light shielding portion 235 and the second projection optical element can be made substantially the same. That is, in the optical axis direction, the distance between the focusing position of the modulated beam L33 on the major axis side and the first projection optical element and the distance between the focusing position of the modulated beam L33 on the major axis side and the second projection optical element can be made substantially the same. This makes it possible to improve the distortion characteristics of the optical device 12, 12a.

[0129] As described above, it is preferable that the first galvanometer mirror 371 changes the reflection direction of the modulated beam L33 in the minor axis direction. This allows the width of the opening 2350 in the major axis side light shielding portion 235 in the major axis direction (i.e., the width in the left-right direction in FIG. 6 ) to be reduced. As a result, it is possible to prevent non-zero-order diffracted light on the major axis side from entering the opening 2350, and the light modulator 22 can accurately modulate the spot light array.

[0130] As described above, the first optical system 21, 21a preferably includes a beam shaper 213. The beam shaper 213 preferably converts the intensity distribution of the laser light L31 in the major axis direction from a Gaussian distribution to a top-hat distribution in the major axis direction of the shaped beam L32 at the modulation plane. This makes it possible to increase the total amount of light input while reducing the maximum power density of the shaped beam L32 incident on the optical modulator 22. Therefore, it is possible to increase the amount of light input to the optical modulator 22 while reducing the risk of damage to the optical modulator 22. As a result, it is possible to suitably increase the power density of the modulated beam L33 irradiated onto the target object.

[0131] As described above, it is preferable that the beam shaper 213 converts the intensity distribution of the laser light L31 in the minor axis direction from a Gaussian distribution, thereby converting the intensity distribution of the shaped beam L32 in the minor axis direction on the modulation plane into a top-hat distribution as well. This makes it possible to further increase the total amount of input light while further reducing the maximum power density of the shaped beam L32 incident on the optical modulator 22.

[0132] As described above, it is preferable that no optical element is disposed between the scanning mechanism 237 and the long axis side light blocking portion 235. This allows the structure of the optical device 12, 12a to be further simplified.

[0133] As described above, a PLV is preferably used as the optical modulator 22. Because a PLV has high power resistance, it is particularly suitable for the optical modulator 22 that requires an increased amount of input light.

[0134] The above-described three-dimensional printing apparatus 1 includes an optical device 12, 12a, a laser light source 11, and a material holding unit (the printing unit 141 in the above example). The laser light source 11 emits laser light L31 to the optical device 12, 12a. The material holding unit holds a printing material 91, which is the object to be irradiated with the modulated beam L33 from the optical device 12, 12a. As described above, in the three-dimensional printing apparatus 1, the structure of the optical device 12, 12a can be simplified. Therefore, the structure of the three-dimensional printing apparatus 1 can be simplified and made smaller.

[0135] The optical devices 12 and 12a and the three-dimensional modeling device 1 described above can be modified in various ways.

[0136] For example, the optical modulator 22 is not necessarily limited to an LPLV, and may be a PLV other than an LPLV. Also, as the optical modulator 22, devices other than a PLV, such as a Grating Light Valve (GLV) (registered trademark) or a Digital Micromirror Device (DMD), may be used.

[0137] The scanning mechanism 237 does not necessarily have to be a galvano scanner, but may be a scanning mechanism having another structure, such as a polygon laser scanner.

[0138] In the optical device 12, 12a, the beam shaper 213 does not necessarily have to be a single optical element, but may be composed of multiple optical elements. The beam shaper 213 may convert only the intensity distribution in the major axis direction of the laser beam L31 into a top hat distribution, without converting the intensity distribution in the minor axis direction of the laser beam L31 into a top hat distribution. Alternatively, in the optical device 12, 12a, the beam shaper 213 that converts the intensity distribution of the laser beam L31 into a top hat distribution may be omitted.

[0139] In the optical device 12 or 12 a, other optical elements may be disposed between the scanning mechanism 237 and the long axis side light blocking portion 235 .

[0140] The optical devices 12 and 12a may be provided in a three-dimensional printing device having a structure different from that of the above-described three-dimensional printing device 1. Furthermore, the optical devices 12 and 12a do not necessarily need to be provided in the three-dimensional printing device 1, and may be used in various devices other than three-dimensional printing devices (for example, laser processing machines such as laser marking devices and laser drilling devices).

[0141] The configurations in the above-described embodiment and each modification may be combined as appropriate as long as they are not mutually contradictory.

[0142] While the invention has been particularly illustrated and described, it should be understood that the foregoing description is illustrative and not restrictive, and that numerous modifications and variations are possible without departing from the scope of the invention.

[0143] REFERENCE SIGNS LIST 1 Three-dimensional modeling device 11 Laser light source 12, 12a Optical device 21, 21a First optical system 22 Optical modulator 23, 23a Second optical system 91 Modeling material 92 Scanned surface 141 Modeling unit 213 Beam shaper 231, 231a First lens 232, 232a Second lens 233, 233a Third lens 234 Fourth lens 235 Long axis side light shielding unit 236 Short axis side light shielding unit 237 Scanning mechanism 371 First galvanometer mirror 372 Second galvanometer mirror L31 Laser light L32 Shaped beam L33 Modulated beam

Claims

1. An optical device for irradiating an object with a spot light array for scanning, comprising: a first optical system for shaping laser light into a shaped beam that is long in a major axis direction; an optical modulator for modulating the shaped beam to form a modulated beam having a pattern in the major axis direction; and a second optical system for guiding the modulated beam to a scanned surface of the object to form a spot light array extending in the major axis direction on the scanned surface and scanning the spot light array on the scanned surface, wherein the second optical system comprises: a minor axis side light shielding portion that is arranged at a focusing position on the minor axis side of the modulated beam and blocks non-zeroth order diffracted light on the minor axis side of the modulated beam; a first projection optical element that is arranged between the minor axis side light shielding portion and the scanned surface and focuses the modulated beam in the major axis direction; and a major axis side light shielding portion that is arranged between the first projection optical element and the scanned surface at a focusing position on the major axis side of the modulated beam by the first projection optical element and blocks non-zero order diffracted light on the major axis side of the modulated beam. An optical device comprising: a second projection optical element arranged between the long axis side light shielding portion and the scanned surface, which forms a spot light array on the scanned surface by converging the modulated beam that has passed through the long axis side light shielding portion in the short axis direction and focusing it on the scanned surface; and a scanning mechanism arranged adjacent to the long axis side light shielding portion between the first projection optical element and the second projection optical element, which scans the modulated beam that is incident on the long axis side light shielding portion or the modulated beam that has passed through the long axis side light shielding portion in at least one of the long axis direction and the short axis direction, wherein the second optical system optically conjugates the modulation surface of the optical modulator and the scanned surface in the long axis direction.

2. An optical device according to claim 1, wherein the scanning mechanism is a galvanometer scanner that changes the reflection direction of the modulated beam.

3. An optical device as described in claim 2, wherein the galvanometer scanner comprises: a first galvanometer mirror arranged adjacent to the long axis side shading portion between the first projection optical element and the long axis side shading portion, and configured to change the reflection direction of the modulated beam in one of the long axis direction and the short axis direction by rotating; and a second galvanometer mirror arranged adjacent to the long axis side shading portion between the long axis side shading portion and the second projection optical element, and configured to change the reflection direction of the modulated beam in the other of the long axis direction and the short axis direction by rotating.

4. An optical device according to claim 3, wherein the first galvanometer mirror changes the reflection direction of the modulated beam in the minor axis direction.

5. An optical device as described in claim 1, wherein the first optical system is equipped with a beam shaper that converts the intensity distribution of the laser light in the major axis direction from a Gaussian distribution to make the intensity distribution of the shaped beam in the major axis direction at the modulation plane a top hat distribution.

6. An optical device as described in claim 5, wherein the beam shaper converts the intensity distribution of the laser light in the short axis direction from a Gaussian distribution, so that the intensity distribution of the shaped beam in the short axis direction on the modulation plane also becomes a top hat distribution.

7. An optical device according to claim 1, wherein no optical element is disposed between said scanning mechanism and said long axis side light shielding portion.

8. An optical device according to claim 1, wherein said optical modulator is a PLV.

9. A three-dimensional modeling apparatus comprising: an optical device according to any one of claims 1 to 8; a laser light source which emits the laser light to the optical device; and a material holding section which holds a modeling material which is the object to be irradiated with the modulated beam from the optical device.

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