Optical device and three-dimensional modeling device

Abstract

The present application provides an optical device for irradiating a modulated light beam on an object and a three-dimensional modeling device, which simplifies the structure of a projection optical system and increases the amount of input light to a light modulator. The illumination optical system of the optical device is configured to transform the intensity distribution in the long axis direction of incident light from a Gaussian distribution so that the intensity distribution in the long axis direction of a shaped light beam in the modulation plane of the light modulator is a flat-top distribution, and to guide the incident light to the light modulator in a manner that the light is parallel in the long axis direction and convergent in the short axis direction. A short axis side light shielding portion is arranged at a condensing position of the short axis side of the modulated light beam, which is convergent in the short axis side, emitted from the light modulator, and shields the non-zero order diffracted light of the short axis side of the modulated light beam. A second projection optical element converges the modulated light beam in the short axis direction and condenses it on an irradiation plane. Thus, the structure of the projection optical system can be simplified, and the amount of input light to the light modulator can be increased.

Description

Technical Field

[0001] The present invention relates to an optical device for irradiating a modulated light beam onto an object, and a three-dimensional modeling device having the optical device.

[0002] Reference to relevant applications

[0003] This application claims the benefit of priority to Japanese Patent Application JP2022-129836, filed on August 17, 2022, and incorporates the entire disclosure of that application. Background Technology

[0004] In recent years, SLS (Selective Laser Sintering) type 3D modeling devices have been developed, which perform 3D modeling by irradiating modulated lasers onto modeling materials such as metal powder or resin powder and sintering the material. In these 3D modeling devices, there is a demand for increased productivity. One method studied is the use of an optical modulator to form linear patterned light, enabling the simultaneous irradiation of multiple light spots. However, in this case, to ensure the power density (i.e., light intensity per unit area) of the laser irradiating the modeling material, high power density light is sometimes used in the optical modulator used to form the patterned light. If a laser with a Gaussian intensity distribution is used to irradiate the optical modulator, the peak intensity (i.e., maximum intensity) on the modulation surface of the modulator becomes excessively large, potentially damaging the optical modulator.

[0005] Therefore, in the three-dimensional modeling apparatus disclosed in Japanese Patent Application Publication No. 2021-165769 (Document 1), a scheme was proposed to increase the amount of light input to the light modulator without damaging the light modulator by flattening the intensity distribution of the laser incident on the light modulator through a flat-top beam shaper.

[0006] However, in the three-dimensional modeling device of Reference 1, a relatively large number of optical elements are provided in the projection optical system that guides the laser modulated by the light modulator to the object. For example, in this projection optical system, in order to block the non-zero-order diffraction light in the laser modulated by the light modulator and guide only the zero-order light to the modeling material, a cylindrical lens is provided at a position adjacent to the light modulator, and a light-blocking part is provided at the focusing position of the cylindrical lens.

[0007] On the other hand, in such high-power 3D modeling devices, in order to more accurately focus the modulated laser onto the modeling material, it is necessary to improve the performance and configuration accuracy of optical components such as lenses that constitute the projection optical system. Therefore, it is necessary to simplify the structure of the projection optical system, for example, by reducing the number of optical components that constitute the projection optical system. In addition, the simplification of the projection optical system structure and the increase of the amount of light injected into the light modulator can also be achieved in the optical device of a device set outside the 3D modeling device (such as a laser marking device). Summary of the Invention

[0008] The purpose of this invention is to provide an optical device for irradiating a modulated beam onto an object, thereby simplifying the structure of the projection optical system and increasing the amount of light input to the light modulator.

[0009] An optical device according to a preferred embodiment of the present invention comprises: an illumination optical system for shaping a laser beam into a long beam along its long axis; an optical modulator for modulating the shaped beam into a modulated beam; and a projection optical system for guiding the modulated beam to an illumination surface of an object. The illumination optical system includes a beam shaper and illumination optical elements. The illumination optical system is configured such that by transforming the intensity distribution of the incident light along its long axis from a Gaussian distribution, the intensity distribution of the shaped beam along its long axis in the modulation surface of the optical modulator becomes a flat-topped distribution, and the incident light is guided to the optical modulator as parallel light along its long axis and convergent light along its short axis. The optical modulator has a plurality of modulation elements arranged in a two-dimensional pattern, and the optical modulator modulates in the long axis direction but does not modulate in the short axis direction. The projection optical system includes: a short-axis light-blocking portion disposed at a focusing position on the short-axis side of the modulated beam emitted from the light modulator, where the short-axis side is converging light, and blocking non-zero-order diffracted light on the short-axis side of the modulated beam; a first projection optical element that converges the modulated beam passing through the short-axis light-blocking portion in the long-axis direction; a long-axis light-blocking portion disposed at a focusing position of the first projection optical element on the long-axis side of the modulated beam, and blocking non-zero-order diffracted light on the long-axis side of the modulated beam; and a second projection optical element that converges the modulated beam passing through the long-axis light-blocking portion in the short-axis direction and focuses it on the illumination surface. The modulation surface and the illumination surface are optically conjugate in the long-axis direction using the projection optical system.

[0010] Based on the above optical device, the structure of the projection optical system can be simplified and the amount of light input to the light modulator can be increased.

[0011] Preferably, the projection optical system further comprises a third projection optical element located between the short-axis side light-shielding portion and the first projection optical element. The modulated beam passing through the short-axis side light-shielding portion becomes parallel light in the short-axis direction using the third projection optical element and the first projection optical element. The first projection optical element has a focal position in the short-axis direction that is the same as that in the long-axis direction. The short-axis side light-shielding portion and the illumination surface are optically conjugate in the short-axis direction using the projection optical system.

[0012] Preferably, the illumination optical system transforms the intensity distribution of the laser beam along its short axis from a Gaussian distribution, thereby making the intensity distribution of the shaped beam in the modulation surface along its short axis also a flat-top distribution.

[0013] Preferably, the illumination optical element is a lens, and in the illumination optical system, no optical elements other than the lens are disposed between the beam shaper and the light modulator.

[0014] Preferably, the modulated light beam emitted from the light modulator is directly incident on the short axis side light shield without passing through other optical elements.

[0015] Preferably, the optical modulator is a PLV.

[0016] Preferably, the beam shaper is an optical element that causes the incident light to spread at different divergence angles in the long axis direction and the short axis direction.

[0017] Preferably, the shaped beam emitted from the illumination optical system is incident obliquely onto the modulation surface at a predetermined incident angle, and the modulated beam, modulated and reflected by the modulation surface, is incident onto the projection optical system.

[0018] The present invention also provides a three-dimensional modeling apparatus. A preferred embodiment of the three-dimensional modeling apparatus of the present invention includes: the aforementioned optical device; a laser source that emits the laser beam into the optical device; and a scanning unit that scans the object irradiated by the modulated beam from the optical device onto a modeling material.

[0019] Preferably, the scanning unit has a galvanometer reflector, which changes the direction of travel of the modulated beam by rotating.

[0020] The above-mentioned objects, as well as other objects, features, methods, and advantages, will become apparent from the detailed description of the invention as follows, with reference to the accompanying drawings. Attached Figure Description

[0021] Figure 1This is a diagram showing the structure of a three-dimensional modeling device according to one embodiment.

[0022] Figure 2 This is a diagram representing an optical modulator.

[0023] Figure 3 This is a diagram showing the structure of an optical device.

[0024] Figure 4 It is a diagram showing the optical path in an optical device.

[0025] Figure 5 It is a diagram showing the optical path in an optical device.

[0026] Figure 6 This is a three-dimensional view showing the light-blocking part on the short axis side.

[0027] Figure 7 This is a three-dimensional view showing the light-blocking part on the long axis side.

[0028] Explanation of reference numerals in the attached figures

[0029] 1. Three-dimensional modeling device

[0030] 11 Laser source

[0031] 12 Optical devices

[0032] 13 Scanning Department

[0033] 21 Illumination Optical System

[0034] 22 Optical modulator

[0035] 23 Projection Optical System

[0036] 91. Molding Materials

[0037] 133 Galvanometer reflector

[0038] 134 Irradiation surface

[0039] 213 Beam Shaper

[0040] 214 Illumination Optical Components

[0041] 221 pixels (modulation element)

[0042] 224 modulation surface

[0043] 231 First projection optical element

[0044] 232 Second projection optical element

[0045] 233 Third projection optical element

[0046] 235 Long axis side light-blocking section

[0047] 236 Short axis side light-shielding part

[0048] L31 laser

[0049] L32 Shaping Beam

[0050] L33 Modulated Beam Detailed Implementation

[0051] Figure 1 This diagram illustrates the structure of a three-dimensional modeling apparatus 1 according to one embodiment of the present invention. The three-dimensional modeling apparatus 1 is an SLS (Selective Laser Sintering) type three-dimensional modeling apparatus that performs three-dimensional modeling by irradiating a powdered or paste-like modeling material with a modulated laser, causing the material to sinter or melt. The modeling material can be, for example, metal, engineering plastic, ceramic, or synthetic resin. The modeling material may also include a variety of materials.

[0052] The three-dimensional modeling device 1 includes a laser light source 11, an optical device 12, a scanning unit 13, and a material supply mechanism 14. Figure 1 The longitudinal section shows the material supply mechanism 14. In the three-dimensional modeling apparatus 1, a laser L31 emitted from the laser source 11 is guided by the optical device 12 to the scanning unit 13, which scans the modeling material 91 within the modeling space 140 of the material supply mechanism 14. As a result, the laser-irradiated portions of the modeling material 91 are sintered. Then, by repeatedly supplying the modeling material 91 to the modeling space 140 and scanning the modeling material 91 with the laser, a three-dimensional model is formed. Figure 1 In the accompanying drawings, for ease of understanding, the various structures of the optical device 12 are enclosed in double-dotted lines.

[0053] In the 3D modeling apparatus 1, based on design data (e.g., CAD data) of the predetermined 3D model to be manufactured, a control unit (not shown) controls the structure of the laser light source 11, optical device 12, scanning unit 13, and material supply mechanism 14, etc. This control unit is, for example, a general-purpose computer equipped with a processor, memory, input / output unit, and bus. Furthermore, the structure of the control unit can be modified in various ways.

[0054] Laser source 11 emits laser light L31 into optical device 12. Laser source 11 is, for example, a fiber laser source. The wavelength of laser light L31 is, for example, 1.070 μm. Furthermore, the type of laser source 11 and the wavelength of laser light L31 can be varied.

[0055] The optical device 12 modulates the laser L31 from the laser source 11 into a modulated beam L33 and illuminates the scanning unit 13. The optical device 12 includes an illumination optical system 21, a light modulator 22, and a projection optical system 23. As described later, the illumination optical system 21 and the projection optical system 23 each include multiple optical elements such as lenses.

[0056] The illumination optics system 21 shapes the laser L31 from the laser source 11 into a roughly rectangular beam L32 that is longer in one direction (hereinafter referred to as the "major axis direction") and guides it to the light modulator 22. In other words, the cross-sectional shape of the shaped beam L32 is a roughly rectangular shape that is longer in the major axis direction and shorter in the minor axis direction perpendicular to the major axis direction. The major axis direction and the minor axis direction are directions perpendicular to the direction of travel of the shaped beam L32 (i.e., the optical axis direction). In addition, the cross-sectional shape of the shaped beam L32 is the shape of the shaped beam L32 in a plane perpendicular to the direction of travel of the shaped beam L32. In the following description, as described above, the cross-section of light refers to the cross-section of the light in a plane perpendicular to the direction of travel of the light. The cross-sectional shape of the shaped beam L32 can also be understood as a roughly straight line extending along the major axis direction. The shape of the irradiation area of ​​the shaped beam L32 on the light modulator 22 is, for example, a roughly rectangular shape with a length of about 27 mm in the major axis direction and a length of about 1 mm in the minor axis direction.

[0057] The light modulator 22 modulates the shaped beam L32 from the illumination optics system 21 into a modulated beam L33 and guides it to the projection optics system 23. The light modulator 22 may be, for example, an LPLV (Linear Planar Light Valve), which is a type of PLV (Planar Light Valve).

[0058] Figure 2 This is a simplified diagram illustrating the structure of an optical modulator 22 (i.e., LPLV). The optical modulator 22 includes a plurality of generally rectangular pixels 221 arranged adjacent to each other in a matrix (i.e., a two-dimensional arrangement) on a substrate (not shown). In the optical modulator 22, the surface of these pixels 221 is called a modulation surface 224. Figure 2 In the example shown, there are M pixels 221 arranged vertically and N pixels 221 arranged horizontally in the figure. Figure 2 Lateral and shaping beam L32 (refer to) Figure 1 Corresponding to the direction of the major axis of ) Figure 2 The longitudinal direction corresponds to the short axis direction of the shaping beam L32.

[0059] Each pixel 221 is a modulation element having a fixed member 222 and a movable member 223. The fixed member 222 is a planar, generally rectangular member fixed to the substrate, with a generally circular opening in the center. The movable member 223 is a generally circular member disposed at the opening of the fixed member 222. On the upper surface of the fixed member 222 (i.e., Figure 2 A fixed reflective surface is provided on the front side of the movable member 223 in a direction perpendicular to the paper surface. A movable reflective surface is provided on the upper surface of the movable member 223. The movable member 223 can be aligned with the front side of the paper surface. Figure 2 The paper moves vertically.

[0060] In each pixel 221, by changing Figure 2 The relative positions of the fixed member 222 and the movable member 223 in the direction perpendicular to the paper plane allow the reflected light from the pixel 221 to switch between zero-order light (i.e., normal reflection light) and non-zero-order diffracted light. In other words, within the pixel 221, light modulation using a diffraction lattice is achieved by the relative movement of the movable member 223 relative to the fixed member 222. The zero-order light emitted from the light modulator 22 passes through the projection optical system 23 (see reference 222). Figure 1 The light is guided to the scanning unit 13. In addition, the non-zero order diffraction light (mainly first order diffraction light) emitted from the light modulator 22 is blocked by the projection optical system 23 and does not reach the scanning unit 13.

[0061] In the optical modulator 22, from... Figure 2 The diffraction states of the reflected light from the M pixels 221 arranged vertically in a column (hereinafter also referred to as a "pixel column") are the same. That is, if the reflected light from one pixel 221 is zero-order light, the reflected light from all other pixels 221 in the pixel column containing that pixel 221 (i.e., M-1 pixels 221) is also zero-order light. Furthermore, if the reflected light from one pixel 221 is non-zero-order diffracted light, the reflected light from all other pixels 221 in the pixel column containing that pixel 221 is also non-zero-order diffracted light. In other words, in the light modulator 22, modulation is not performed in the short-axis direction of the shaping beam L32, but modulation is performed in the long-axis direction.

[0062] In the projection optical system 23, for the N columns of pixels arranged in a row along the long axis of the shaping beam L32 on the light modulator 22, the reflected light from the M pixels 221 contained in each pixel column is accumulated and guided to the scanning unit 13. As a result, the power density of the modulated beam L33 irradiating the shaping material 91 from the scanning unit 13 can be increased.

[0063] Furthermore, in the optical modulator 22, M pixels 221 (i.e., M modulation elements) in a pixel column can be regarded as a modulation element corresponding to a unit space. The optical modulator 22 functions as an optical modulator having N modulation elements arranged in a column along the long axis direction of the shaping beam L32 on the optical modulator 22.

[0064] Figure 1 The projection optical system 23 shown focuses and guides the modulated beam L33 from the light modulator 22 to the scanning unit 13. In other words, the scanning unit 13 is the object irradiated by the modulated beam L33 from the optical device 12. The modulated beam L33 irradiates the irradiation surface 134 of the scanning unit 13. Figure 1 In the diagram, the irradiated surface 134 is represented by a black circle (described later). Figure 3 (The same applies to China).

[0065] The scanning unit 13 reflects the modulated beam L33 from the projection optical system 23 of the optical device 12 and scans the modeling material 91 within the modeling space 140 of the material supply mechanism 14. The scanning unit 13 includes a relay lens 131 and a galvanometer scanner 132. The galvanometer scanner 132 is a scanning mechanism that includes a galvanometer reflector 133 and a galvanometer motor (not shown). The illumination surface 134 is the imaging surface of the modulated beam L33 from the projection optical system 23, located upstream of the relay lens 131 in the illumination direction of the optical device (i.e., between the projection optical system 23 and the relay lens 131). In the scanning unit 13, the imaging surface 134 of the modulated beam L33 from the projection optical system 23 is optically conjugate with the surface layer of the modeling material 91 using the relay lens 131. Furthermore, in the galvanometer scanner 132, the galvanometer reflector 133 is rotated by the galvanometer motor, thereby changing the travel direction of the modulated beam L33 reflected by the galvanometer reflector 133. As a result, the modulated beam L33 illuminating the molding material 91 scans in a scanning direction corresponding to the minor axis direction of the modulated beam L33.

[0066] The material supply mechanism 14 includes a shaping section 141 and a supply section 142. The shaping section 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 shape of the internal space of the first cylinder 143 when viewed from above is, for example, approximately rectangular. The first piston 144 is a generally flat or generally cylindrical member housed in the internal space of the first cylinder 143, and its shape when viewed from above is approximately 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 shaping section 141, the three-dimensional space surrounded by the inner surface of the first cylinder 143 and the upper surface of the first piston 144 becomes a shaping space 140 for three-dimensional shaping using a modulated beam L33.

[0067] The supply unit 142 includes a second cylinder 145, a second piston 146, and a scraper 147. The second cylinder 145 is a cylindrical member extending vertically and is disposed adjacent to the side of the first cylinder 143. The internal space of the second cylinder 145 has a generally rectangular shape when viewed from above. The second piston 146 is a generally flat or generally cylindrical member housed within the internal space of the second cylinder 145, and its shape when viewed from above is approximately the same as the internal space of the second cylinder 145. The second piston 146 is movable vertically within the internal space of the second cylinder 145. In the supply unit 142, the 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 for storing the predetermined shaping material 91 supplied to the shaping unit 141. The scraper 147 is a rod-shaped (e.g., generally cylindrical) member that extends horizontally through the upper opening of the second cylinder 145. The scraper 147 can move horizontally along the upper end face of the second cylinder 145.

[0068] In the supply section 142, the second piston 146 rises a predetermined distance, lifting the shaping material 91 within the second cylinder 145 upwards. Then, a scraper 147 moves from the second cylinder 145 onto the first cylinder 143, supplying the shaping material 91, which protrudes upwards beyond the upper surface of the second cylinder 145, into the shaping space 140 of the shaping section 141. The upper surface of the shaping material 91, held within the shaping space 140, is at a predetermined height (e.g., the same height as the upper surface of the first cylinder 143).

[0069] In the three-dimensional modeling apparatus 1, the modeling material 91 within the modeling space 140 is scanned by the aforementioned modulated beam L33. As a result, the surface portion of the modeling material 91 within the modeling space 140 that is irradiated by the modulated beam L33 is sintered, forming a portion equivalent to one layer in a scenario where the three-dimensional model is divided into multiple layers stacked vertically. When the scanning of the modeling material 91 within the modeling space 140 by the modulated beam L33 ends, the first piston 144 descends a predetermined distance. Then, as described above, the modeling material 91 is supplied to the modeling space 140 from the supply unit 142, and the scanning by the modulated beam L33 is performed. In the three-dimensional modeling apparatus 1, by repeatedly supplying the modeling material 91 to the modeling space 140 and scanning the modeling material 91 within the modeling space 140 by the modulated beam L33, a three-dimensional model is formed within the modeling space 140.

[0070] Next, refer to Figures 3 to 5 The detailed structure of the optical device 12 will be described. Figure 3 This is a diagram showing the structure of the optical device 12. Figure 4 and Figure 5This is a schematic diagram showing the optical paths of the laser L31, the shaping beam L32, and the modulation beam L33 in the optical device 12. (See diagram for example.) Figure 3 As shown, in the optical device 12 of this embodiment, the illumination optical system 21 and the projection optical system 23 are arranged at an angle (i.e., such that the optical axis J2 of the illumination optical system 21 intersects the optical axis J3 of the projection optical system 23). Figure 4 and Figure 5 In order to make the diagram easier to understand, the positions of the illumination optical system 21 and the projection optical system 23 are changed so that the optical axis J2 of the illumination optical system 21 and the optical axis J3 of the projection optical system 23 are aligned as a straight line.

[0071] exist Figure 4 In the diagram, the optical paths of the shaping beam L32 and the modulation beam L33 are shown such that their minor axes align with the direction perpendicular to the plane of the paper. Figure 4 In the diagram, the major axes of the shaping beam L32 and the modulation beam L33 align with the vertical direction. Additionally, in... Figure 5 In the diagram, the optical paths of the shaping beam L32 and the modulation beam L33 are shown such that their major axes align with the direction perpendicular to the plane of the paper. Figure 5 In the figure, the minor axis directions of the shaping beam L32 and the modulation beam L33 are consistent with the up and down directions.

[0072] The illumination optical system 21 of the optical device 12 includes a collimating lens 211, a beam shaper 213, and an illumination optical element 214. The collimating lens 211 is, for example, a spherical lens. Furthermore, in... Figures 3 to 5 In the example shown, collimating lens 211 is a single lens, but it can also be composed of two or more lenses. Furthermore, collimating lens 211 is not limited to a spherical lens; it can be a cylindrical lens or an aspherical lens.

[0073] The beam shaper 213 is a flat-top beam shaper that transforms the intensity distribution (hereinafter referred to as "intensity distribution") along the long and short axes of the cross-section of the collimated beam L321 (i.e., the incident light) with a Gaussian distribution into a flat-top distribution with a wider (i.e., generally flat at the top) region of maximum intensity. The beam shaper 213 is, for example, an optical element. In this embodiment, the beam shaper 213 is an aspherical concave lens, but various optical elements other than aspherical concave lenses can also be used as the beam shaper 213.

[0074] The illumination optical element 214 is, for example, a lens, in Figures 3 to 5In the example shown, a spherical convex lens is used. In the following description, the illumination optical element 214 will also be referred to as "convex lens 214". Convex lens 214 can also be an aspherical convex lens. In the illumination optical system 21, the collimating lens 211, the beam shaper 213, and the convex lens 214 are arranged in this order in the direction of light travel from the laser source 11 towards the light modulator 22. Furthermore, in Figures 3 to 5 In the illustrated illumination optical system 21, no optical element other than the single convex lens 214 is disposed between the beam shaper 213 and the light modulator 22. In other words, the light beam L322 emitted from the beam shaper 213 is directly incident on the convex lens 214 without passing through any other optical element, and is emitted from the convex lens 214 as the shaped beam L32. The shaped beam L32 emitted from the convex lens 214 is directly incident on the light modulator 22 without passing through any other optical element.

[0075] As described above, the illumination optics system 21 shapes the laser L31 emitted from the laser source 11 into a shaped beam L32 and guides it to the light modulator 22. The laser L31 emitted from the laser source 11 passes through the collimating lens 211, the beam shaper 213, and the convex lens 214 of the illumination optics system 21, thereby being shaped into a shaped beam L32 with desired shapes in both the minor and major axes and guided to the light modulator 22. The shaped beam L32 refers to the beam emitted from the illumination optics system 21 and incident on the light modulator 22.

[0076] The intensity distributions along the minor and major axes of the laser L31 incident on the illumination optical system 21 are Gaussian distributions. In reality, these intensity distributions are not strictly Gaussian distributions; sometimes they approximate the shape of a Gaussian function. In the following description, both strictly Gaussian distributions and distributions approximating Gaussian distributions are collectively referred to as "Gaussian distributions".

[0077] In the illumination optical system 21, the laser L31 passes through the collimating lens 211, thus becoming a collimated beam L321 that is parallel in both the major and minor axes, and is then incident on the beam shaper 213. The cross-sectional shape of the collimated beam L321 incident on the beam shaper 213 is, for example, approximately circular. The intensity distribution of the collimated beam L321 between the collimating lens 211 and the beam shaper 213 (i.e., before incident on the beam shaper 213) is as follows: Figure 4 as well as Figure 5 As shown in the rectangular frame at the bottom of the ray path diagram, the ray path diagram has a Gaussian distribution along the major and minor axes.

[0078] The collimated beam L321 passes through the beam shaper 213, thus becoming a beam L322 that extends significantly in the long axis direction and extends less significantly in the short axis direction, and is incident on the convex lens 214. The beam shaper 213 causes the light rays in the central high-intensity region of the Gaussian distribution in the incident light, which has a Gaussian intensity distribution in the long axis direction, to diverge at a greater angle than the light rays in the outer low-intensity region of the Gaussian distribution. That is, the beam shaper 213 causes the collimated beam L321 (i.e., the incident light) incident on the beam shaper 213 to extend with different divergence angles in the long axis direction and the short axis direction. After passing through the beam shaper 213 and the convex lens 214, the intensity distributions of the collimated beam L321 in the long axis direction and the short axis direction are gradually shaped into an ideal flat-top distribution (also called a rectangular distribution) as it propagates along the optical path. Figure 4 and Figure 5 The lower side of the optical path diagram is shown in a rectangular frame. The intensity distribution of the shaped beam L32 that reaches the optical modulator 22 through the beam shaper 213 and the convex lens 214 is flat-topped in both the long axis and short axis directions.

[0079] The collimated beam L321 passes through the beam shaper 213 and the convex lens 214, thus becoming a shaped beam L32 that is parallel in the long axis direction and convergent in the short axis direction, and is incident on the modulation surface 224 of the light modulator 22. The cross-sectional shape of the shaped beam L32 incident on the light modulator 22 is, as described above, approximately rectangular with a longer long axis. The length of the cross-section of the shaped beam L32 incident on the light modulator 22 in the long axis direction is greater than the diameter of the approximately circular cross-section of the collimated beam L321 incident on the beam shaper 213. Furthermore, the length of the cross-section of the shaped beam L32 incident on the light modulator 22 in the short axis direction is less than the diameter of the cross-section of the collimated beam L321 incident on the beam shaper 213. Since the focusing position of the convex lens 214 on the short axis of the shaping beam L32 is located on the opposite side of the illumination optical system 21 (i.e., the projection optical system 23 side of the light modulator 22) through the light modulator 22, the shaping beam L32 is incident on the light modulator 22 before reaching the focusing position on the short axis side.

[0080] The intensity distribution of the shaped beam L32 incident on the optical modulator 22 (i.e., the intensity distribution of the shaped beam L32 in the modulation surface 224 of the optical modulator 22) is flat-topped in both the long-axis and short-axis directions, as shown in... Figure 4 and Figure 5 The lower side of the optical path diagram is shown, enclosed by a rectangular frame.

[0081] The shaped beam L32 incident on the light modulator 22 is modulated by the light modulator 22 and becomes the modulated beam L33 incident on the projection optical system 23. The modulated beam L33 emitted from the light modulator 22 and incident on the projection optical system 23 is parallel light in the long axis direction and convergent light in the short axis direction.

[0082] The projection optical system 23 includes a first projection optical element 231, a second projection optical element 232, a third projection optical element 233, a long-axis side light-blocking portion 235, and a short-axis side light-blocking portion 236. In the projection optical system 23, the short-axis side light-blocking portion 236, the third projection optical element 233, the first projection optical element 231, the long-axis side light-blocking portion 235, and the second projection optical element 232 are arranged in this order in the direction of travel of the modulated beam L33 from the light modulator 22 toward the scanning portion 13.

[0083] The short-axis light-shielding portion 236 is, for example, a flat plate member with a generally rectangular opening 236a extending parallel to the long axis direction at its central portion. The material of the short-axis light-shielding portion 236 is, for example, a metal such as stainless steel or copper, or ceramic. The third projection optical element 233 is, for example, a lens. Figures 3 to 5 The example shown is a cylindrical convex lens. In the following description, the third projection optical element 233 will also be referred to as "third lens 233". As described above, the third projection optical element 233 is located between the short axis side light-blocking portion 236 and the first projection optical element 231.

[0084] The first projection optical element 231 is, for example, a lens. Figures 3 to 5 The example shown is a spherical convex lens. In the following description, the first projection optical element 231 will be referred to as "first lens 231". The first projection optical element 231 has a focal point in the short axis direction that is the same as in the long axis direction. Furthermore, the first lens 231 may also be, for example, an aspherical convex lens. The long axis side light-shielding portion 235 is, for example, a flat plate member with a generally rectangular opening 235a extending parallel to the short axis direction at its center. The material of the long axis side light-shielding portion 235 is, for example, a metal such as stainless steel or copper, or ceramic. The second projection optical element 232 is, for example, a lens, in... Figures 3 to 5 The example shown is a spherical convex lens. In the following description, the second projection optical element 232 will also be referred to as "second lens 232". The second lens 232 may also be an aspherical convex lens, for example.

[0085] The short-axis light-blocking portion 236 is disposed at the focusing position on the short axis side of the modulated beam L33 emitted from the light modulator 22 (i.e., the focusing position on the short axis side of the shaping beam L32 emitted from the illumination optical system 21). Furthermore, the short-axis light-blocking portion 236 can be disposed substantially at this focusing position on the short axis side, or it can be disposed at a position slightly offset from this focusing position in the travel direction of the modulated beam L33.

[0086] exist Figures 3 to 5 In the illustrated projection optical system 23, no other optical elements such as lenses are disposed between the light modulator 22 and the short-axis light-shielding part 236. In other words, the modulated beam L33 emitted from the light modulator 22 is directly incident on the short-axis light-shielding part 236 without passing through other optical elements. In addition, the modulated beam L33 passing through the opening 236a of the short-axis light-shielding part 236 is directly incident on the third lens 233 without passing through other optical elements.

[0087] The long-axis light-blocking portion 235 is disposed at the rear focal position of the first lens 231. The rear focal position of the first lens 231 coincides with the front focal position of the second lens 232. The position where the long-axis light-blocking portion 235 is disposed is the long-axis focusing position of the modulated beam L33 passing through the third lens 233 and the first lens 231. Furthermore, the long-axis light-blocking portion 235 can be disposed substantially at this focusing position on the long axis, or it can be disposed at a position slightly offset from this focusing position in the travel direction of the modulated beam L33.

[0088] In the projection optical system 23, the short-axis side light-blocking part 236 and the illumination surface 134 of the scanning part 13 are optically conjugate in the short-axis direction. Figure 5 In the example shown, the short-axis light-shielding portion 236 and the illumination surface 134 of the scanning portion 13 are optically conjugate in the short-axis direction via the third lens 233, the first lens 231, and the second lens 232. Furthermore, in the projection optical system 23, the modulation surface 224 of the light modulator 22 and the illumination surface 134 of the scanning portion 13 are optically conjugate in the long-axis direction. Figure 5 In the example shown, the modulation surface 224 of the light modulator 22 and the illumination surface 134 of the scanning unit 13 are optically conjugate in the long axis direction through the first lens 231 and the second lens 232.

[0089] As described above, the projection optical system 23 guides the modulated beam L33 from the light modulator 22 toward the scanning section 13. Specifically, the modulated beam L33, which is convergent on the short axis, is focused on the short axis at the focusing position where the short axis light shield 236 is disposed, and passes through the opening 236a of the short axis light shield 236. More specifically, the zero-order light and the non-zero-order diffracted light on the long axis of the modulated beam L33, which are reflected by the light modulator 22, pass through the opening 236a of the short axis light shield 236. The cross-sectional shape of the modulated beam L33 passing through the opening 236a of the short axis light shield 236 is approximately straight or approximately rectangular in the long axis direction. The intensity distribution of the modulated beam L33 passing through the opening 236a of the short axis light shield 236 is as follows: Figure 4 and Figure 5 The lower part of the optical path diagram is shown enclosed by a rectangular frame. It has a roughly flat-top distribution along the major axis and a sinc distribution along the minor axis. In reality, the intensity distribution along the minor axis of the modulated beam L33 is sometimes not a strict sinc distribution, but rather a distribution with a shape approximating the sinc function. In the following description, both the strict sinc distribution and the distribution approximating the sinc distribution will be referred to as the "sinc distribution".

[0090] On the other hand, in the modulated beam L33, the non-zero order diffracted light on the short axis side is blocked by the short axis side shielding part 236. The non-zero order diffracted light mainly consists of first-order diffracted light (i.e., (+1) order diffracted light and (-1) order diffracted light), but also includes diffracted light of second order and above. Figure 6 As shown, the non-zero order diffracted light on the short axis side illuminates the generally linear or generally rectangular irradiation area 81 that is longer in the long axis direction at the portion of the short axis side shielding part 236 that is above and below the opening 236a (i.e., on both sides of the opening 236a in the short axis direction).

[0091] like Figure 4 and Figure 5 As shown, the cross-section of the modulated beam L33 passing through the opening 236a of the short-axis side light-blocking part 236 expands in the short-axis direction as it travels in the direction of travel of the modulated beam L33, and becomes parallel light in the short-axis direction after passing through the third lens 233 and the first lens 231. The modulated beam L33 does not refract in the long-axis direction when passing through the third lens 233, and is focused by the first lens 231, with the light focused at the rear focal position of the first lens 231 (i.e., the front focal position of the second lens 232).

[0092] As described above, a long-axis light-blocking portion 235 is disposed at the focusing position (i.e., the rear focal position of the first lens 231) on the long axis side of the modulation beam L33. The modulation beam L33 passing through the first lens 231 passes through the opening 235a of the long-axis light-blocking portion 235. Specifically, the reflected light after being reflected by the light modulator 22, i.e., the zero-order light in the modulation beam L33, passes through the opening 235a of the long-axis light-blocking portion 235. The cross-sectional shape of the modulation beam L33 passing through the opening 235a of the long-axis light-blocking portion 235 is approximately straight or approximately rectangular in the short axis direction. The intensity distribution of the modulation beam L33 passing through the opening 235a of the long-axis light-blocking portion 235 is as follows: Figure 4 and Figure 5 As shown in the image, the lower side of the optical path diagram is enclosed by a rectangular frame. The path is sinc-shaped along the major axis and flat-topped along the minor axis.

[0093] On the other hand, the non-zero order diffracted light (mainly first order diffracted light) on the long axis side of the modulated beam L33 is blocked by the long axis side light-blocking part 235. For example... Figure 7 As shown, the non-zero order diffracted light on the long axis side illuminates the light-shielding part 235 on the long axis side, at the left and right sides of the opening 235a (i.e., on both sides of the long axis direction of the opening 235a) in the figure, towards the generally linear or generally rectangular irradiation area 82 extending along the short axis direction.

[0094] like Figure 4 and Figure 5 As shown, the cross-section of the modulated beam L33 passing through the opening 235a of the long-axis side light-blocking portion 235 expands in the long-axis direction as it travels in the direction of travel of the modulated beam L33. Passing through the second lens 232, it becomes parallel light in the long-axis direction. Furthermore, in the short-axis direction, the modulated beam L33, as parallel light incident on the second lens 232, converges in the short-axis direction, focusing on the illumination surface 134 of the scanning portion 13 located at the rear focal position of the second lens 232.

[0095] The cross-sectional shape of the modulated beam L33 on the illumination surface 134 of the scanning unit 13 is approximately rectangular, elongated along its major axis. The intensity distribution of the modulated beam L33 on the illumination surface 134 of the scanning unit 13 is as follows: Figure 4 and Figure 5 As shown in the lower part of the optical path diagram, which is surrounded by a rectangular frame, the optical path has a flat-top distribution along the major axis and a sinc distribution along the minor axis. Since the sinc distribution is roughly the same as the Gaussian distribution in that it has a main peak, the modulated beam L33 can be properly focused onto the illumination surface 134 of the scanning section 13.

[0096] As mentioned above, in Figure 1In the three-dimensional modeling apparatus 1 shown, a modulated light beam L33, appropriately focused on the irradiation surface 134, scans the modeling material 91 within the modeling space 140 via the scanning unit 13. Then, by repeatedly supplying the modeling material 91 to the modeling space 140 and scanning the modeling material 91 with the laser, a three-dimensional model is formed.

[0097] Next, an example will be described regarding the specific size of the cross-section of the shaped beam L32 and the cross-section of the modulated beam L33 in the optical device 12. In this example, the wavelength λ of the laser L31 emitted from the laser source 11 is 1.070 μm, and the diameter (1 / e) of the approximately circular cross-section of the collimated beam L321 incident on the beam shaper 213 in the illumination optical system 21 is... 2 The width is 5mm. The paraxial focal distance f on the long axis side of the beam shaper 213 is... x The paraxial focal distance f on the minor axis side is -46mm. y The focal length is -1250mm. Additionally, the paraxial focal distance f0 of the convex lens 214 is 250mm. The distance L1 between the beam shaper 213 and the convex lens 214 is approximately 204mm, and the distance L2 between the convex lens 214 and the modulation surface 224 of the light modulator 22 is equal to f0. In this case, the illumination area of ​​the shaped beam L32 on the modulation surface 224 becomes a roughly rectangular shape with a length of approximately 27mm in the major axis direction and approximately 1mm in the minor axis direction. As described above, the shaped beam L32 incident on the light modulator 22 is parallel light in the major axis direction and convergent light in the minor axis direction.

[0098] The distance between the combined focal point of the beam shaper 213 and the convex lens 214 on the short axis (i.e., f) y The focal distance (to f0) is approximately 260 mm. The focusing position on the short axis side of the shaped beam L32 incident on the light modulator 22 (i.e., the position where the short axis side light-blocking part 236 is arranged) is approximately 52 mm away from the modulation surface 224 of the light modulator 22 (i.e., the projection optical system 23 side). The number of openings NA forming this focusing position is 0.01, and the focusing diameter (i.e., the dark ring diameter of the sinc function) of the modulated beam L33 in the short axis direction at this focusing position is approximately 130 μm.

[0099] In the projection optical system 23, the paraxial focal distance f3 of the third lens 233 is 158 mm, the paraxial focal distance f1 of the first lens 231 is 240 mm, and the paraxial focal distance f2 of the second lens 232 is 60 mm. The distance L5 between the third lens 233 and the first lens 231 is approximately 120 mm. The combined focal distance between the third lens 233 and the first lens 231 on the minor axis side (i.e., the combined focal distance of f3 and f1) is approximately 136 mm. Based on the ratio of this combined focal distance to the paraxial focal distance f2 of the second lens 232, the focusing diameter (i.e., the dark ring diameter of the sinc function) of the modulation beam L33 in the minor axis direction on the illumination surface 134 of the scanning unit 13 is approximately 0.44 times, or approximately 57 μm, the focusing diameter (approximately 130 μm) of the modulation beam L33 in the minor axis direction at the aforementioned focusing position. Furthermore, the length of the modulated beam L33 on the illumination surface 134 of the scanning unit 13 in the long axis direction is approximately 0.25 times the length of the shaped beam L32 on the modulation surface 224 of the light modulator 22, i.e., approximately 6.74 mm, based on the ratio of the paraxial focal distance f1 of the first lens 231 to the paraxial focal distance f2 of the second lens 232.

[0100] Furthermore, the pixel spacing of the light modulator 222 pixels 221 along both the major and minor axes is 25.5 μm, and the angle between the first-order diffracted light and the zero-order diffracted light is approximately 42 mrad (milliradians). Therefore, in the minor-axis side shading portion 236, the distance between the zero-order light and the first-order diffracted light along the minor axis is approximately 2.2 mm. Additionally, in the major-axis side shading portion 235, the distance between the zero-order light and the first-order diffracted light along the major axis is approximately 10 mm.

[0101] like Figure 3 As shown, in the optical device 12, the illumination optical system 21 is arranged obliquely relative to the modulation surface 224 of the light modulator 22, and the rear end of the illumination optical system 21, i.e., the convex lens 214, is opposite to the modulation surface 224 of the light modulator 22. The optical axis J2 of the illumination optical system 21 is obliquely relative to the normal direction of the modulation surface 224 of the light modulator 22, and the shaped light beam L32 emitted from the illumination optical system 21 toward the light modulator 22 is obliquely incident on the modulation surface 224 of the light modulator 22 at a predetermined incident angle greater than 0°.

[0102] Furthermore, in the optical device 12, the projection optical system 23 is also arranged obliquely relative to the modulation surface 224 of the light modulator 22, and the front end of the projection optical system 23, namely the short axis side light-shielding part 236, faces the modulation surface 224 of the light modulator 22. The optical axis J3 of the projection optical system 23 is oblique relative to the normal direction of the modulation surface 224 of the light modulator 22, and the modulated beam L33, after being modulated and reflected by the modulation surface 224 of the light modulator 22, is incident on the projection optical system 23 along the optical axis J3 of the projection optical system 23. In addition, the reflection angle of the modulated beam L33 in the modulation surface 224 of the light modulator 22 (which can be regarded as the reflection angle of the shaping beam L32) is greater than 0°.

[0103] If we call the angle (acute angle) between the optical axis J2 of the illumination optical system 21 and the optical axis J3 of the projection optical system 23 θ, then as the angle θ increases, the interaction between the convex lens 214 and other structures of the illumination optical system 21 and the short-axis light-blocking part 236 and other structures of the projection optical system 23 will change. Figure 3 Separating the illumination optical system 21 and the projection optical system 23 in the vertical direction suppresses mechanical interference. Therefore, structures such as the convex lens 214 can be brought closer to the light modulator 22 along the optical axis J2, and structures such as the short-axis light-shielding part 236 can be brought closer to the light modulator 22 along the optical axis J3. Thus, the optical device 12 can be... Figure 3 The size of the optical device 12 is reduced in the left-right direction. On the other hand, as the angle θ increases, the size of the optical device 12 in the up-down direction increases.

[0104] Furthermore, as the angle θ decreases, the illumination optical system 21 and the projection optical system 23... Figure 3 The structures are close together in the vertical direction, thus enabling the optical device 12 to be miniaturized in this direction. On the other hand, as the angle θ decreases, the structures of the convex lens 214, etc., in the illumination optical system 21 and the structures of the short-axis side light-shielding part 236, etc., in the projection optical system 23 become more compact. Figure 3 The optical devices 12 are close together in the vertical direction. Therefore, in order to suppress mechanical interference between the illumination optical system 21 and the projection optical system 23, it is necessary to move the various structures such as the convex lens 214 away from the light modulator 22 in the optical axis J2 direction, and to move the various structures such as the short axis side light-blocking part 236 away from the light modulator 22 in the optical axis J3 direction. As a result, the size of the optical device 12 in the horizontal direction becomes larger.

[0105] In order to make the optical device 12 Figure 3 Miniaturization in the left-right direction and miniaturization in the up-down direction are achieved simultaneously. The angle θ between the optical axis J2 of the illumination optical system 21 and the optical axis J3 of the projection optical system 23 is preferably 10° or more and 30° or less, more preferably 10° or more and 20° or less.

[0106] As explained above, the optical device 12 is a device for irradiating a modulated beam L33 onto an object (scanning unit 13 in the above example). The optical device 12 includes an illumination optical system 21, a light modulator 22, and a projection optical system 23. The illumination optical system 21 shapes the laser L31 into a shaped beam L32 that is long in the long axis direction. The light modulator 22 modulates the shaped beam L32 into a modulated beam L33. The projection optical system 23 guides the modulated beam L33 to the illumination surface 134 of the object. The illumination optical system 21 includes a beam shaper 213 and an illumination optical element 214 (a convex lens 214 in the above example). The illumination optical system 21 is configured such that by transforming the intensity distribution of the incident light in the long axis direction from a Gaussian distribution, the intensity distribution of the shaped beam L32 in the modulation surface 224 of the light modulator 22 in the long axis direction is a flat-top distribution. Furthermore, the illumination optical system 21 is configured to guide the incident light to the light modulator 22 in a manner that is parallel light in the long axis direction and convergent light in the short axis direction. The light modulator 22 has a plurality of modulation elements (pixels 221 in the above example) arranged in two dimensions, and the light modulator 22 modulates in the long axis direction but does not modulate in the short axis direction.

[0107] The projection optical system 23 includes a short-axis light-blocking portion 236, a first projection optical element 231 (in the above example, a first lens 231), a long-axis light-blocking portion 235, and a second projection optical element 232 (in the above example, a second lens 232). The short-axis light-blocking portion 236 is positioned at the short-axis focusing position of the modulated beam L33 emitted from the light modulator 22, and blocks the non-zero-order diffracted light of the modulated beam L33 on the short-axis side. The first projection optical element 231 focuses the modulated beam L33 that has passed through the short-axis light-blocking portion 236 in the long-axis direction. The long-axis light-blocking portion 235 is positioned at the long-axis focusing position of the first projection optical element 231 on the first projection optical element 231, and blocks the non-zero-order diffracted light of the modulated beam L33 on the long-axis side. The second projection optical element 232 converges the modulated beam L33, which has passed through the long-axis side light-blocking part 235, in the short-axis direction and focuses it onto the illumination surface 134. The modulation surface 224 and the illumination surface 134 are optically conjugated in the long-axis direction by the projection optical system 23.

[0108] Thus, in the optical device 12, by utilizing the illumination optical system 21 equipped with the beam shaper 213 and the illumination optical element 214, the intensity distribution of the laser L31 along its long axis is made into a flat-top distribution. This reduces the maximum power density of the shaped beam L32 incident on the light modulator 22 and increases the total amount of light input. Furthermore, in the optical device 12, there is no need to include an optical element in the projection optical system 23 to focus the modulated beam L33 modulated by the light modulator 22 towards the short-axis shielding portion 236. Therefore, the number of optical elements, such as lenses, constituting the projection optical system 23 can be reduced. In other words, the structure of the projection optical system 23 can be simplified in the optical device 12, and the amount of light input to the light modulator 22 can be increased. Moreover, in the optical device 12, the modulation surface 224 of the light modulator 22 and the illumination surface 134 of the object are optically conjugate along their long axis, thus enabling the modulation of light in the modulation surface 224 to be accurately reflected on the illumination surface 134.

[0109] As described above, preferably, the projection optical system 23 further includes a third projection optical element 233 located between the short-axis side light-shielding portion 236 and the first projection optical element 231. The modulated beam L33 passing through the short-axis side light-shielding portion 236 becomes parallel light in the short-axis direction using the third projection optical element 233 and the first projection optical element 231. The first projection optical element 231 has the same focal position in the short-axis direction as in the long-axis direction. Moreover, it is preferable that the short-axis side light-shielding portion 236 and the illumination surface 134 of the object are optically conjugate in the short-axis direction using the projection optical system 23. As a result, the modulated beam L33 can be appropriately focused on the illumination surface 134 of the object in the short-axis direction. Consequently, the power density of the modulated beam L33 illuminating the object can be appropriately increased.

[0110] As described above, preferably, the illumination optical system 21 transforms the intensity distribution of the laser L31 along its short axis from a Gaussian distribution, thereby causing the intensity distribution of the shaped beam L32 in the modulation surface 224 along its short axis to also be a flat-top distribution. This reduces the maximum power density of the shaped beam L32 incident on the light modulator 22 and further increases the total amount of light input. That is, it further increases the amount of light input to the light modulator 22.

[0111] As described above, preferably, the illumination optical element 214 is a lens (a convex lens 214 in the above example). Furthermore, in the illumination optical system 21, it is preferable that no optical elements other than this lens are disposed between the beam shaper 213 and the light modulator 22. This simplifies the structure of the illumination optical system 21. As a result, the flexibility in the arrangement of the illumination optical system 21 is increased, and the optical device 12 can be miniaturized.

[0112] As described above, preferably, the modulated beam L33 emitted from the light modulator 22 is directly incident on the short-axis side light-shielding portion 236 without passing through other optical elements. This further simplifies the structure of the projection optical system 23. As a result, the degree of freedom in the configuration of the projection optical system 23 can be increased, and the optical device 12 can be miniaturized.

[0113] As described above, preferably, the optical modulator 22 is a PLV. Because PLVs have high power tolerance, they are particularly suitable for optical modulators 22 that require increased input light volume.

[0114] As described above, preferably, the beam shaper 213 is an optical element that expands the incident light by different divergence angles in the long axis and short axis directions. This simplifies the structure of the illumination optical system 21 and generates a shaped beam L32 with a long cross-sectional shape in the long axis direction. As a result, the optical device 12 can be further miniaturized. Furthermore, the beam shaper 213 can also converge the incident light in the short axis direction.

[0115] In the optical device 12, preferably, the shaped beam L32 emitted from the illumination optical system 21 is incident obliquely onto the modulation surface 224 at a predetermined incident angle, and the modulated beam L33, modulated and reflected by the modulation surface 224, is incident onto the projection optical system 23. As described above, in the optical device 12, since the structure of the projection optical system 23 is simplified, the optical device 12 with the above-described structure, in which the illumination optical system 21 and the projection optical system 23 are arranged opposite to the modulation surface 224, is able to achieve the following in the direction in which the illumination optical system 21 and the projection optical system 23 are arranged (i.e., Figure 1 as well as Figure 3 Miniaturization in the vertical direction.

[0116] The 3D modeling apparatus 1 includes the aforementioned optical device 12, laser light source 11, and scanning unit 13. The laser light source 11 emits a laser beam L31 towards the optical device 12. The scanning unit 13 scans the object being irradiated by the modulated beam L33 from the optical device 12 onto the modeling material. As described above, by appropriately increasing the power density of the modulated beam L33 irradiating the object (i.e., the scanning unit 13) in the optical device 12, the power density of the modulated beam L33 irradiating the modeling material 91 can be appropriately increased in the 3D modeling apparatus 1. As a result, the modeling speed of the object in the 3D modeling apparatus 1 can be increased, thereby improving productivity. Furthermore, as described above, by simplifying the structure of the projection optical system 23 in the optical device 12, the optical device 12 can be miniaturized, thus also enabling the miniaturization of the 3D modeling apparatus 1.

[0117] As described above, preferably, the scanning unit 13 includes a galvanometer reflector 133 that changes the travel direction of the modulated beam L33 by rotation. This enables high-precision and high-speed scanning of the modulated beam L33 from the optical device 12.

[0118] In the 3D modeling apparatus 1, as described above, it is preferable that the scanning direction of the modulation beam L33 based on the scanning unit 13 is a direction corresponding to the minor axis direction of the modulation beam L33. On the modeling material 91, since the intensity distribution along the minor axis direction of the modulation beam L33 is a sinc distribution, a bright ring exists around the focal point, and the area ahead of the focal point in the scanning direction (i.e., the minor axis direction) is preheated by this bright ring. Therefore, when scanning this preheated area with the modulation beam L33, the heating time of this area can be shortened. As a result, the productivity of the 3D modeling apparatus 1 can be further improved.

[0119] Various modifications can be made to the aforementioned optical device 12 and three-dimensional modeling device 1.

[0120] For example, the configuration of the illumination optics system 21, the light modulator 22, and the projection optics system 23 is not limited to Figure 1 and Figure 3 The configuration shown can be modified in various ways. For example, the shaped beam L32 emitted from the illumination optics 21 does not necessarily need to be incident at an angle relative to the modulation surface 224 of the light modulator 22; it can also be incident approximately perpendicularly.

[0121] The optical modulator 22 is not necessarily limited to an LPLV; it can also be a PLV other than an LPLV. In addition, the optical modulator 22 can also be an optical modulator other than a PLV, such as a GLV (Grating Light Valve) (registered trademark) or a DMD (Digital Micromirror Device).

[0122] The divergence angle of the incident light in the beam shaper 213 does not necessarily need to be different in the major and minor axis directions; it can also be the same in both directions. Furthermore, the beam shaper 213 does not necessarily need to consist of only one optical element; it can be composed of multiple optical elements. The beam shaper 213 is not necessarily limited to an aspherical concave lens; for example, it can be a refractive optical element such as a freeform lens, or a diffractive optical element (DOE). In the beam shaper 213, the intensity distribution of the laser L31 in the minor axis direction does not necessarily need to be transformed into a flat-top distribution.

[0123] In the illumination optical system 21, the illumination optical element 214 does not necessarily need to be a convex lens; it can also be other optical elements. Furthermore, the illumination optical element 214 does not necessarily need to consist of only one optical element; it can also consist of multiple optical elements. In the illumination optical system 21, other optical elements besides the illumination optical element 214 can be configured between the beam shaper 213 and the light modulator 22.

[0124] In the projection optical system 23, an optical element may also be arranged between the light modulator 22 and the short-axis side light shield 236. In this case, the modulated beam L33 emitted from the light modulator 22 is incident on the short-axis side light shield 236 via the optical element.

[0125] In the projection optical system 23, the first projection optical element 231, the second projection optical element 232, and the third projection optical element 233 are not limited to a single lens; for example, they may be composed of two or more optical elements. Furthermore, optical elements other than the first projection optical element 231, the second projection optical element 232, and the third projection optical element 233 may be added to the projection optical system 23. The material, shape, and structure of the long-axis side light-blocking portion 235 and the short-axis side light-blocking portion 236 of the projection optical system 23 are not limited to those described above and can be modified in various ways.

[0126] In the optical device 12, the short-axis side light-shielding portion 236 and the irradiation surface 134 may not be optically conjugate in the short-axis direction. For example, the irradiation surface 134 may be slightly offset from the conjugate position of the short-axis side light-shielding portion 236 in the short-axis direction.

[0127] In the scanning unit 13 of the three-dimensional modeling device 1, a scanning mechanism with other structures, such as a polygonal laser scanner, may be provided instead of the galvanometer scanner 132. Alternatively, the scanning unit 13 is not limited to a scanning unit that changes the travel direction of the modulation beam L33 from the projection optical system 23. For example, when the irradiation position of the modulation beam L33 is fixed, it may be a moving mechanism such as a linear motor that moves the modeling part 141 that holds the modeling material 91 in the horizontal direction.

[0128] The optical device 12 does not necessarily need to be installed in the three-dimensional modeling device 1. For example, it can also be used in a laser processing machine such as a laser marking device.

[0129] The structures in the above-described embodiments and their variations can be appropriately combined as long as they do not contradict each other.

[0130] Although the invention has been described and illustrated in detail, the above description is merely an example and is not intended to limit it. Therefore, various modifications and implementations are possible without departing from the scope of the invention.

Claims

1. An optical device for irradiating a modulated light beam onto an object, characterized in that, have: The illumination optics system shapes the laser into a long beam along its long axis. An optical modulator modulates the shaped beam into a modulated beam; and The projection optical system guides the modulated beam onto the illumination surface of the object. The illumination optical system includes a beam shaper and illumination optical elements. The illumination optical system is configured such that by transforming the intensity distribution of the incident light along its long axis from a Gaussian distribution, the intensity distribution of the shaped beam in the modulation surface of the light modulator along its long axis becomes a flat-top distribution, and the incident light is guided to the light modulator in a manner that makes it parallel in the long axis direction and convergent in the short axis direction. The optical modulator has multiple modulation elements arranged in a two-dimensional pattern. The optical modulator modulates along the long axis but does not modulate along the short axis. The projection optical system has: The short-axis light-blocking part is disposed at the focusing position of the short-axis side of the modulated beam emitted from the light modulator, where the short-axis side is the converging light, and blocks the non-zero order diffracted light of the short-axis side of the modulated beam; The first projection optical element causes the modulated light beam that has passed through the short axis side light shield to converge in the long axis direction; The long axis side light-blocking part is disposed at the focusing position of the first projection optical element on the long axis side of the modulation beam, and blocks the non-zero order diffraction light on the long axis side of the modulation beam; as well as The second projection optical element causes the modulated light beam that has passed through the long-axis side light-blocking part to converge in the short-axis direction and focus on the irradiation surface. The modulation surface and the illumination surface are optically conjugate along the long axis using the projection optics system.

2. The optical device as claimed in claim 1, characterized in that, The projection optical system also has a third projection optical element located between the short axis side light-blocking portion and the first projection optical element. The modulated light beam passing through the short-axis side light-blocking part becomes parallel light in the short-axis direction using the third projection optical element and the first projection optical element. The first projection optical element has the same focal position in the minor axis direction as in the major axis direction. The short-axis side shading portion and the irradiation surface are optically conjugate in the short-axis direction using the projection optics system.

3. The optical device as claimed in claim 1, characterized in that, The illumination optical system transforms the intensity distribution of the laser beam along its minor axis from a Gaussian distribution, thereby making the intensity distribution of the shaped beam in the modulation surface along its minor axis also a flat-top distribution.

4. The optical device as described in any one of claims 1 to 3, characterized in that, The illumination optics element is a lens. In the illumination optical system, no optical elements other than the lens are disposed between the beam shaper and the light modulator.

5. The optical device as described in any one of claims 1 to 3, characterized in that, The modulated beam emitted from the light modulator is directly incident on the short axis side light shield without passing through other optical elements.

6. The optical device as claimed in any one of claims 1 to 3, characterized in that, The optical modulator is a planar optical valve.

7. The optical device as claimed in any one of claims 1 to 3, characterized in that, The beam shaper is an optical element that causes incident light to spread at different divergence angles in the long axis direction and the short axis direction.

8. The optical device as claimed in any one of claims 1 to 3, characterized in that, The shaped beam emitted from the illumination optical system is incident obliquely onto the modulation surface at a predetermined incident angle, and the modulated beam, modulated and reflected by the modulation surface, is incident onto the projection optical system.

9. A three-dimensional modeling device, characterized in that, have: The optical device according to any one of claims 1 to 3; A laser source emits the laser beam into the optical device; and The scanning unit is the object being irradiated by the modulated beam from the optical device, which scans the modeling material with the modulated beam.

10. The three-dimensional modeling device as described in claim 9, characterized in that, The scanning unit has a galvanometer reflector, which changes the direction of travel of the modulated beam by rotating.

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