Optical devices and 3D printing devices

Abstract

To increase the amount of light to be inputted to an optical modulator while simplifying the structure of a projection optical system.SOLUTION: An illumination optical system 21 is configured to convert an intensity distribution of incident light in a long axis direction from a Gaussian distribution to bring an intensity distribution of a shaped beam L32 on a modulation surface 224 of an optical modulator 22 in the long axis direction into a top hat distribution, and to guide the incident light to the optical modulator 22 as parallel light in the long axis direction and as convergent light in a short axis direction. A short axis side shielding portion 236 is disposed at a condensing position on a short axis side of a modulated beam L33 which is emitted from the optical modulator 22 and is convergent light on a short axis side and blocks a non-zero-order diffracted beam on the short axis side of the modulated beam L33. A second projection optical element 232 converges the modulated beam L33 in the short axis direction and condenses the modulated beam on an irradiated surface 134. Thus, it is possible to increase the amount of light to be inputted to the optical modulator 22 while simplifying the structure of a projection optical system 23.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an optical device that irradiates a modulated beam onto an object, and a three-dimensional shaping device including the optical device.

Background Art

[0002] In recent years, an SLS (Selective Laser Sintering) type three-dimensional shaping device that performs three-dimensional shaping by irradiating a shaped material such as metal powder or resin powder with a laser beam modulated thereon to sinter the shaped material has been used. In this three-dimensional shaping device, improvement in productivity is required. As a method therefor, for example, by forming a linear pattern light using an optical modulator, it has been considered possible to irradiate a plurality of spots at once. At this time, the optical modulator for forming the pattern light may be irradiated with light having a high power density in order to ensure the power density of the laser light irradiated onto the shaped material (that is, the light intensity per unit area). At this time, when irradiating the optical modulator with laser light having a Gaussian distribution of intensity distribution, the peak intensity (that is, the maximum intensity) on the modulation surface of the modulator becomes excessive, and there is a risk of damaging the optical modulator.

[0003] Therefore, in the three-dimensional shaping device of Patent Document 1, it has been proposed to increase the amount of incident light to the optical modulator without damaging the optical modulator by flattening the intensity distribution of the laser light incident on the optical modulator with a top hat beam shaper.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0006] On the other hand, in such high-power 3D printing devices, it is necessary to improve the performance and placement accuracy of optical elements such as lenses that constitute the projection optical system in order to more accurately focus the modulated laser light onto the printing material. For this reason, there is a need to simplify the structure of the projection optical system, such as by reducing the number of optical elements that constitute the projection optical system. Furthermore, simplification of the projection optical system structure and an increase in the amount of light input to the optical modulator are also required in optical devices installed in devices other than 3D printing devices (for example, laser marking devices).

[0007] This invention has been made in view of the above problems, and aims to increase the amount of light input to the optical modulator while simplifying the structure of the projection optical system. [Means for solving the problem]

[0008] One aspect of the present invention is an optical device for irradiating an object with a modulated beam, comprising: an illumination optical system for shaping laser light into a long, shaped beam in the longitudinal direction; an optical modulator for modulating the shaped beam into a modulated beam; and a projection optical system for guiding the modulated beam to the irradiation surface of the object. The illumination optical system comprises a beam shaper and illumination optical elements. The illumination optical system is configured to convert the intensity distribution of the incident light in the longitudinal direction from a Gaussian distribution to a top-hat distribution for the intensity distribution of the shaped beam in the longitudinal direction at the modulation surface of the optical modulator, and to guide the incident light to the optical modulator as parallel light in the longitudinal direction and converged light in the short direction. The optical modulator comprises a plurality of modulation elements arranged in two dimensions, and performs modulation in the longitudinal direction but not in the short direction. The projection optical system comprises: a short-axis side light-shielding portion positioned at the focal point on the short axis side of the modulated beam, whose short axis side is converged light emitted from the optical modulator, and which blocks non-zero-order diffracted light on the short axis side of the modulated beam; a first projection optical element that focuses the modulated beam that has passed through the short-axis side light-shielding portion in the long axis direction; a long axis side light-shielding portion positioned at the focal point on the long axis side of the modulated beam by the first projection optical element, and which blocks non-zero-order diffracted light on the long axis side of the modulated beam; and a second projection optical element that focuses the modulated beam that has passed through the long axis side light-shielding portion in the short axis direction and focuses it on the illumination surface. The projection optical system makes the modulated surface and the illumination surface optically conjugate with respect to the long axis direction.

[0009] Aspect 2 of the present invention is an optical apparatus according to aspect 1, wherein 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 third projection optical element and the first projection optical element cause the modulated beam that has passed through the short-axis side light-shielding portion to become parallel light in the short-axis direction. The first projection optical element has the same focal position in the short-axis direction as in the long-axis direction. The projection optical system makes the short-axis side light-shielding portion and the illumination surface optically conjugate in the short-axis direction.

[0010] A third aspect of the present invention is an optical apparatus according to aspect 1 (or aspect 1 or 2), wherein the illumination optical system converts the intensity distribution of the laser light in the short axis direction from a Gaussian distribution to a top-hat distribution, thereby making the intensity distribution of the shaping beam in the short axis direction on the modulation plane a top-hat distribution.

[0011] Aspect 4 of the present invention is an optical device according to any one of aspects 1 to 3, wherein the illumination optical element is a single lens, and in the illumination optical system, no optical elements other than the single lens are arranged between the beam shaper and the light modulator.

[0012] Aspect 5 of the present invention is an optical apparatus according to any one of aspects 1 to 3 (or any one of aspects 1 to 4), wherein the modulated beam emitted from the optical modulator is directly incident on the short-axis light-shielding portion without passing through other optical elements.

[0013] Aspect 6 of the present invention is an optical device according to any one of aspects 1 to 3 (or any one of aspects 1 to 5), wherein the optical modulator is a PLV.

[0014] Aspect 7 of the present invention is an optical device according to any one of aspects 1 to 3 (or any one of aspects 1 to 6), wherein the beam shaper is a single optical element that spreads the incident light at mutually different divergence angles in the long axis direction and the short axis direction.

[0015] Aspect 8 of the present invention is an optical apparatus according to any one of aspects 1 to 3 (or any one of aspects 1 to 7), wherein the shaping beam emitted from the illumination optical system is incident obliquely on the modulation surface at a predetermined incident angle, and the modulated beam, which is modulated and reflected by the modulation surface, is incident on the projection optical system.

[0016] Aspect 9 of the present invention is a three-dimensional shaping apparatus, comprising an optical device according to any one of Aspects 1 to 3 (or any one of Aspects 1 to 8), a laser light source that emits the laser light to the optical device, an object irradiated with the modulated beam from the optical device, and a scanning unit that scans the modulated beam on a shaping material.

[0017] Aspect 10 of the present invention is the three-dimensional shaping apparatus of Aspect 9, wherein the scanning unit comprises a galvanometer mirror that changes the traveling direction of the modulated beam by rotating.

Advantages of the Invention

[0018] In the present invention, it is possible to increase the amount of incident light to the optical modulator while simplifying the structure of the projection optical system.

Brief Description of the Drawings

[0019] [Figure 1] It is a diagram showing the configuration of a three-dimensional shaping apparatus according to an embodiment. [Figure 2] It is a diagram showing an optical modulator. [Figure 3] It is a diagram showing the configuration of an optical device. [Figure 4] It is a diagram showing the optical path in an optical device. [Figure 5] It is a diagram showing the optical path in an optical device. [Figure 6] It is a perspective view showing a short-axis side light-shielding portion. [Figure 7] It is a perspective view showing a long-axis side light-shielding portion.

Modes for Carrying Out the Invention

[0020] Figure 1 shows the configuration of a three-dimensional molding apparatus 1 according to one embodiment of the present invention. The three-dimensional molding apparatus 1 is an SLS (Selective Laser Sintering) type three-dimensional molding apparatus that performs three-dimensional molding by irradiating powdered or paste-like molding material with modulated laser light and sintering or melting the molding material. The molding material is, for example, metal, engineering plastic, ceramics, or synthetic resin. The molding material may contain multiple types of materials.

[0021] The 3D printing apparatus 1 comprises a laser light source 11, an optical device 12, a scanning unit 13, and a material supply mechanism 14. Figure 1 shows the material supply mechanism 14 in a longitudinal cross-section. In the 3D printing apparatus 1, the laser beam L31 emitted from the laser light source 11 is guided to the scanning unit 13 by the optical device 12, and the scanning unit 13 scans the printing material 91 in the printing space 140 of the material supply mechanism 14. As a result, the parts of the printing material 91 that are irradiated with the laser beam are sintered. Then, by repeating the supply of printing material 91 to the printing space 140 and the scanning of the laser beam on the printing material 91, a 3D object is formed. In Figure 1, each component of the optical device 12 is enclosed by a dashed line to facilitate understanding of the figure.

[0022] In the 3D printing apparatus 1, the configuration of the laser light source 11, optical device 12, scanning unit 13, and material supply mechanism 14, etc., is controlled by a control unit (not shown) based on the design data (e.g., CAD data) of the 3D object to be manufactured. This control unit is, for example, a conventional computer equipped with a processor, memory, input / output unit, and bus. The configuration of the control unit may be changed in various ways.

[0023] 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. Note that the type of laser light source 11 and the wavelength of the laser light L31 can be changed in various ways.

[0024] The optical device 12 modulates the laser light L31 from the laser light source 11 into a modulated beam L33 and irradiates the scanning unit 13 with it. The optical device 12 comprises an illumination optical system 21, a light modulator 22, and a projection optical system 23. The illumination optical system 21 and the projection optical system 23 each include multiple optical elements such as lenses, as will be described later.

[0025] The illumination optical system 21 shapes the laser light L31 from the laser light source 11 into a roughly 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 roughly rectangular, long in the long axis direction and short in the short axis direction perpendicular to the long axis direction. The long axis direction and the short axis direction are perpendicular to the direction of propagation of the shaped beam L32 (i.e., the optical axis direction). Furthermore, 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 propagation of the shaped beam L32. In the following explanation, the cross-section of light means the cross-section of the light in a plane perpendicular to the direction of propagation of the light, as described above. The cross-sectional shape of the shaped beam L32 can also be considered as a roughly straight line extending in the long axis direction. The shape of the irradiation area of ​​the shaped beam L32 on the optical modulator 22 is, for example, a roughly rectangular shape with a length of approximately 27 mm in the long axis direction and a length of approximately 1 mm in the short axis direction.

[0026] The optical modulator 22 modulates the shaped beam L32 from the illumination optical system 21 into a modulated beam L33 and guides it to the projection 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.

[0027] Figure 2 is a simplified diagram showing the structure of the optical modulator 22 (i.e., LPLV). The optical modulator 22 comprises a plurality of substantially rectangular pixels 221 arranged adjacently in a matrix (i.e., arranged in two dimensions) on a substrate (not shown). In the optical modulator 22, the surface of the plurality of pixels 221 becomes the modulation surface 224. In the example shown in Figure 2, M pixels 221 are arranged vertically and N pixels 221 are arranged horizontally. The horizontal direction in Figure 2 corresponds to the long axis direction of the shaping beam L32 (see Figure 1), and the vertical direction in Figure 2 corresponds to the short axis direction of the shaping beam L32.

[0028] Each pixel 221 is a modulation element comprising a fixed member 222 and a movable member 223. The fixed member 222 is a planar, substantially rectangular member fixed to the substrate, with a substantially circular opening in the 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 front surface in the direction perpendicular to the plane of the paper in Figure 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 plane of the paper in Figure 2.

[0029] At each pixel 221, the relative position of the fixed member 222 and the movable member 223 in the direction perpendicular to the plane of the paper in Figure 2 is changed, thereby switching the reflected light from the pixel 221 between zero-order light (i.e., specular reflection) and non-zero-order diffracted light. In other words, at pixel 221, optical modulation using a diffraction grating is performed by the relative movement of the movable member 223 with respect to the fixed member 222. The zero-order light emitted from the optical modulator 22 is guided to the scanning unit 13 by the projection optical system 23 (see Figure 1). The non-zero-order diffracted light (mainly first-order diffracted light) emitted from the optical modulator 22 is blocked by the projection optical system 23 and does not reach the scanning unit 13.

[0030] In the optical modulator 22, the diffraction state of the reflected light from M pixels 221 arranged in a vertical row in Figure 2 (hereinafter also referred to as the "pixel row") is the same. That is, if the reflected light from one pixel 221 is zero-order light, then the reflected light from all other pixels 221 in the pixel row containing that one pixel 221 (i.e., M-1 pixels 221) is also zero-order light. Also, if the reflected light from one pixel 221 is non-zero-order diffracted light, then the reflected light from all other pixels 221 in the pixel row containing that one pixel 221 is also non-zero-order diffracted light. In other words, the optical modulator 22 does not modulate the shaping beam L32 in the short-axis direction, but modulates it in the long-axis direction.

[0031] In the projection optical system 23, for N rows of pixels arranged in a single line along the long axis of the shaping beam L32 on the optical modulator 22, the reflected light from M pixels 221 contained in each pixel row is integrated and guided to the scanning unit 13. This increases the power density of the modulated beam L33 irradiated from the scanning unit 13 onto the fabrication material 91.

[0032] In addition, in the optical modulator 22, M pixels 221 in one pixel row (i.e., M modulation elements) 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 single row along the long axis of the shaping beam L32 on the optical modulator 22.

[0033] The projection optical system 23 shown in Figure 1 focuses the modulated beam L33 from the optical modulator 22 and guides it to the scanning unit 13. In other words, the scanning unit 13 is the object onto which the modulated beam L33 from the optical device 12 is irradiated. The modulated beam L33 is irradiated onto the irradiation surface 134 of the scanning unit 13. In Figure 1, the irradiation surface 134 is shown as a black circle (the same applies in Figure 3, which will be described later).

[0034] The scanning unit 13 reflects the modulated beam L33 from the projection optical system 23 of the optical device 12 and scans the material 91 in the build space 140 of the material supply mechanism 14. The scanning unit 13 comprises a relay lens 131 and a galvanometer scanner 132. The galvanometer scanner 132 is a scanning mechanism comprising a galvanometer mirror 133 and a galvanometer motor (not shown). The aforementioned illumination surface 134 is an imaging surface where the modulated beam L33 from the projection optical system 23 is imaged, 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 illumination surface 134, which is the imaging surface of the modulated beam L33 from the projection optical system 23, and the surface layer on the material 91 are optically conjugated by the relay lens 131. Furthermore, in the galvanoscanner 132, the galvanosink mirror 133 rotates due to the galvanosink motor, thereby changing the direction of travel of the modulated beam L33 reflected by the galvanosink mirror 133. As a result, the modulated beam L33 irradiated onto the fabrication material 91 is scanned in a scanning direction corresponding to the short axis direction of the modulated beam L33.

[0035] The material supply mechanism 14 comprises a molding section 141 and a supply section 142. The molding section 141 comprises 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 in plan view is, for example, approximately rectangular. The first piston 144 is an approximately flat or columnar member housed in the internal space of the first cylinder 143, and its shape in plan view is approximately the same as 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 molding section 141, the three-dimensional space enclosed by the inner surface of the first cylinder 143 and the upper surface of the first piston 144 becomes the molding space 140 in which three-dimensional molding is performed by the modulated beam L33.

[0036] The supply unit 142 comprises 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 positioned adjacent to the side of the first cylinder 143. The shape of the internal space of the second cylinder 145 in plan view is, for example, approximately rectangular. The second piston 146 is a substantially flat or columnar member housed in the internal space of the second cylinder 145, and its shape in plan view is approximately the same as that of the internal space of the second cylinder 145. The second piston 146 is movable in the vertical direction within the internal space of the second cylinder 145. In the supply unit 142, the three-dimensional space enclosed by the inner surface of the second cylinder 145 and the upper surface of the second piston 146 becomes a storage space where the molding material 91 to be supplied to the molding 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.

[0037] In the supply unit 142, the second piston 146 rises by a predetermined distance, lifting the molding material 91 in the second cylinder 145 upward. Then, as the squeegee 147 moves from above the second cylinder 145 to above the first cylinder 143, the molding material 91 that protrudes above the upper end surface of the second cylinder 145 is supplied into the molding space 140 of the molding unit 141. The upper surface of the molding material 91 held in the molding space 140 is positioned at a predetermined height (for example, the same height as the upper end surface of the first cylinder 143).

[0038] In the 3D printing apparatus 1, the modulated beam L33 described above is scanned over the printing material 91 in the printing space 140. As a result, the area on the surface 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 3D printed object is divided into multiple layers stacked vertically. When the scanning of the modulated beam L33 over the printing material 91 in the printing space 140 is completed, the first piston 144 descends by a predetermined distance. Thereafter, as described above, the printing material 91 is supplied from the supply unit 142 to the printing space 140, and the modulated beam L33 is scanned. In the 3D printing apparatus 1, the supply of printing material 91 to the printing space 140 and the scanning of the printing material 91 in the printing space 140 with the modulated beam L33 are repeated, thereby forming a 3D printed object in the printing space 140.

[0039] Next, the detailed structure of the optical device 12 will be described with reference to Figures 3 to 5. Figure 3 is a diagram showing the configuration of the optical device 12. Figures 4 and 5 are schematic diagrams showing the optical paths of the laser beam L31, the shaping beam L32, and the modulation beam L33 in the optical device 12. As shown in Figure 3, in the optical device 12 according to this embodiment, the illumination optical system 21 and the projection optical system 23 are arranged diagonally (i.e., the optical axis J2 of the illumination optical system 21 and the optical axis J3 of the projection optical system 23 intersect). However, in Figures 4 and 5, in order to facilitate understanding of the diagrams, 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 in a straight line.

[0040] In Figure 4, the optical paths of the shaping beam L32 and the modulation beam L33 are shown such that their short axis directions coincide with the direction perpendicular to the plane of the paper. In Figure 4, the long axis directions of the shaping beam L32 and the modulation beam L33 coincide with the vertical direction in the figure. Similarly, in Figure 5, the optical paths of the shaping beam L32 and the modulation beam L33 are shown such that their long axis directions coincide with the direction perpendicular to the plane of the paper. In Figure 5, the short axis directions of the shaping beam L32 and the modulation beam L33 coincide with the vertical direction in the figure.

[0041] The illumination optical system 21 of the optical device 12 comprises a collimating lens 211, a beam shaper 213, and an illumination optical element 214. The collimating lens 211 is, for example, a spherical lens. In the examples shown in Figures 3 to 5, the collimating lens 211 is a single lens, but the collimating lens 211 may be composed of two or more lenses. Furthermore, the collimating lens 211 is not limited to a spherical lens, but may be a cylindrical lens or an aspherical lens.

[0042] The beam shaper 213 is a top-hat beam shaper that transforms the distribution of light intensity in the long and short axes in the cross-section of the Gaussian-distributed collimated beam L321 (i.e., incident light) incident on the beam shaper 213 from a Gaussian distribution to a top-hat distribution with a wide maximum intensity region (i.e., a substantially flat top). The beam shaper 213 is, for example, a single optical element. In this embodiment, the beam shaper 213 is an aspherical concave lens, but various optical elements other than aspherical concave lenses may be used as the beam shaper 213.

[0043] The illumination optical element 214 is, for example, a single lens, and in the examples shown in Figures 3 to 5, it is a single spherical convex lens. In the following description, the illumination optical element 214 will also be referred to as the "convex lens 214". The convex lens 214 may 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 propagation from the laser light source 11 to the optical modulator 22. In addition, in the illumination optical system 21 illustrated in Figures 3 to 5, no optical elements other than the single convex lens 214 described above are placed between the beam shaper 213 and the optical modulator 22. In other words, the beam L322 emitted from the beam shaper 213 is directly incident on the convex lens 214 without passing through other optical elements, and is emitted from the convex lens 214 as a shaped beam L32. The shaped beam L32 emitted from the convex lens 214 enters the optical modulator 22 directly without passing through any other optical elements.

[0044] As described above, the illumination optical system 21 shapes the laser light L31 emitted from the laser light source 11 into a shaped beam L32 and guides it to the optical modulator 22. The laser light L31 emitted from the laser light source 11 passes through the collimating lens 211, beam shaper 213, and convex lens 214 of the illumination optical system 21, shaping it into a shaped beam L32 having a desired shape in the short axis and long axis directions, and then guides it to the optical modulator 22. The shaped beam L32 refers to the light beam from the time it leaves the illumination optical system 21 until it enters the optical modulator 22.

[0045] The intensity distributions in the short-axis and long-axis directions in the cross-section of the laser beam L31 before it enters the illumination optical system 21 are Gaussian distributions. In reality, these intensity distributions may not be exact Gaussian distributions, but rather distributions with shapes that approximate a Gaussian function. However, in the following explanation, both exact Gaussian distributions and distributions that approximate a Gaussian distribution will be collectively referred to as "Gaussian distributions."

[0046] In the illumination optical system 21, the laser light L31 passes through the collimating lens 211 and becomes a collimated beam L321, which is parallel in the long axis and short axis directions, before being 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 being incident on the beam shaper 213) is a Gaussian distribution in both the long axis and short axis directions, as shown by the rectangular frames enclosed at the bottom of the optical path diagrams in Figures 4 and 5.

[0047] The collimated beam L321 passes through the beam shaper 213, becoming beam L322, which spreads relatively widely in the long axis direction and relatively less in the short axis direction as it travels, and then enters the convex lens 214. The beam shaper 213 diverges the group of rays in the high-intensity central region of the Gaussian intensity distribution of the incident light, which has a Gaussian intensity distribution in the long axis direction, at a larger divergence angle than the group of rays in the low-intensity outer region of the Gaussian distribution. In other words, the beam shaper 213 spreads the collimated beam L321 (i.e., the incident light) entering the beam shaper 213 at different divergence angles in the long axis and short axis directions. The intensity distributions of the collimated beam L321 in the long axis and short axis directions are gradually shaped into an ideal top-hat distribution (also called a rectangular distribution) as they travel along the optical path after passing through the beam shaper 213 and the convex lens 214, respectively. As shown in the rectangular frame below the optical path diagrams in Figures 4 and 5, the intensity distribution of the shaped beam L32 that has passed through the beam shaper 213 and convex lens 214 and reached the optical modulator 22 is a top-hat distribution in both the long axis and short axis directions.

[0048] The collimated beam L321 passes through the beam shaper 213 and the convex lens 214 to become a shaped beam L32, which is parallel in the long axis direction and converged in the short axis direction, and is incident on the modulation surface 224 of the optical modulator 22. As described above, the cross-sectional shape of the shaped beam L32 incident on the optical modulator 22 is a roughly rectangular shape that is long in the long axis direction. The length of the cross-section of the shaped beam L32 incident on the optical modulator 22 in the long axis direction is greater than the diameter of the roughly circular cross-section of the collimated beam L321 incident on the beam shaper 213. Also, the length of the cross-section of the shaped beam L32 incident on the optical modulator 22 in the short axis direction is smaller than the diameter of the cross-section of the collimated beam L321 incident on the beam shaper 213. Since the focal point of the shaping beam L32 formed by the convex lens 214 in the short axis direction is located on the opposite side of the optical modulator 22 from the illumination optical system 21 (i.e., on the projection optical system 23 side of the optical modulator 22), the shaping beam L32 is incident on the optical modulator 22 before it reaches the focal point on the short axis side.

[0049] The intensity distribution of the shaped beam L32 incident on the optical modulator 22 (i.e., the intensity distribution of the shaped beam L32 on the modulation surface 224 of the optical modulator 22) is a top-hat distribution in both the long axis and short axis directions, as shown enclosed in a rectangular frame below the optical path diagrams in Figures 4 and 5.

[0050] The shaping beam L32, which is incident on the optical modulator 22, is modulated by the optical modulator 22 and incident on the projection optical system 23 as a modulated beam L33. The modulated beam L33, which is emitted from the optical modulator 22 and incident on the projection optical system 23, is parallel light in the long axis direction and focused light in the short axis direction.

[0051] The projection optical system 23 comprises a first projection optical element 231, a second projection optical element 232, a third projection optical element 233, a long-axis light-shielding portion 235, and a short-axis light-shielding portion 236. In the projection optical system 23, the short-axis light-shielding portion 236, the third projection optical element 233, the first projection optical element 231, the long-axis light-shielding portion 235, and the second projection optical element 232 are arranged in this order in the direction of propagation of the modulated beam L33 from the optical modulator 22 to the scanning unit 13.

[0052] The short-axis light-shielding portion 236 is, for example, a flat plate member with a substantially rectangular opening 236a extending parallel to the long axis in its central part. The material of the short-axis light-shielding portion 236 is, for example, a metal such as stainless steel or copper, or a ceramic. The third projection optical element 233 is, for example, a lens, and in the example shown in Figures 3 to 5, it is a cylindrical convex lens. In the following description, the third projection optical element 233 will also be referred to as the "third lens 233". As described above, the third projection optical element 233 is located between the short-axis light-shielding portion 236 and the first projection optical element 231.

[0053] The first projection optical element 231 is, for example, a lens, and in the examples shown in Figures 3 to 5, it is a spherical convex lens. In the following description, the first projection optical element 231 will also be referred to as the "first lens 231". The first projection optical element 231 has the same focal position in the direction of the minor axis as in the direction of the major axis. The first lens 231 may be, for example, an aspherical convex lens. The major axis side light shielding portion 235 is, for example, a flat plate member with a substantially rectangular opening 235a extending parallel to the direction of the minor axis in its center. The material of the major axis side light shielding portion 235 may be, for example, a metal such as stainless steel or copper, or a ceramic. The second projection optical element 232 is, for example, a lens, and in the examples shown in Figures 3 to 5, it is a spherical convex lens. In the following description, the second projection optical element 232 will also be referred to as the "second lens 232". The second lens 232 may be, for example, an aspherical convex lens.

[0054] The short-axis side light shielding portion 236 is positioned at the short-axis side focusing position of the modulated beam L33 emitted from the optical modulator 22 (i.e., the short-axis side focusing position of the shaping beam L32 emitted from the illumination optical system 21). However, the short-axis side light shielding portion 236 may be positioned slightly offset from the focusing position in the direction of propagation of the modulated beam L33, as long as it is substantially positioned at the short-axis side focusing position.

[0055] In the projection optical system 23 illustrated in Figures 3 to 5, no other optical elements such as lenses are placed between the optical modulator 22 and the short-axis light-shielding section 236. In other words, the modulated beam L33 emitted from the optical modulator 22 enters the short-axis light-shielding section 236 directly without passing through any other optical elements. Furthermore, the modulated beam L33 that has passed through the aperture 236a of the short-axis light-shielding section 236 enters the third lens 233 directly without passing through any other optical elements.

[0056] The long-axis light-shielding portion 235 is positioned at the rear focal point of the first lens 231. The rear focal point of the first lens 231 coincides with the front focal point of the second lens 232. The position where the long-axis light-shielding portion 235 is positioned is the focal point on the long axis side of the modulated beam L33 after it has passed through the third lens 233 and the first lens 231. However, the long-axis light-shielding portion 235 may be positioned slightly offset from the focal point in the direction of travel of the modulated beam L33, as long as it is substantially positioned at the focal point on the long axis side.

[0057] In the projection optical system 23, the short-axis side light-shielding portion 236 and the illumination surface 134 of the scanning unit 13 are optically conjugate in the short-axis direction. In the example shown in Figure 5, the short-axis side light-shielding portion 236 and the illumination surface 134 of the scanning unit 13 are optically conjugate in the short-axis direction by the third lens 233, the first lens 231, and the second lens 232. In addition, in the projection optical system 23, the modulation surface 224 of the optical modulator 22 and the illumination surface 134 of the scanning unit 13 are optically conjugate in the long-axis direction by the first lens 231 and the second lens 232.

[0058] As described above, the projection optical system 23 guides the modulated beam L33 from the optical modulator 22 to the scanning unit 13. Specifically, the modulated beam L33, whose short-axis side is focused light, is focused on the short-axis side at the focusing position where the short-axis side light shield 236 is located, and passes through the aperture 236a of the short-axis side light shield 236. More specifically, of the modulated beam L33, which is reflected light reflected by the optical modulator 22, the 0th-order light and the non-0th-order diffracted light on the long-axis side pass through the aperture 236a of the short-axis side light shield 236. The cross-sectional shape of the modulated beam L33 passing through the aperture 236a of the short-axis side light shield 236 is approximately straight or approximately rectangular, elongated in the long-axis direction. The intensity distribution of the modulated beam L33 passing through the aperture 236a of the short-axis side light shield 236 is approximately a top-hat distribution in the long-axis direction and a sinc distribution in the short-axis direction, as shown enclosed in a rectangular frame at the bottom of the optical path diagrams in Figures 4 and 5. In reality, the intensity distribution in the short axis direction of the modulated beam L33 may not be a strict sinc distribution, but rather a distribution with a shape that approximates a sinc function. However, in the following explanation, both the strict sinc distribution and distributions that approximate a sinc distribution will be collectively referred to as the "sinc distribution."

[0059] On the other hand, of the modulated beam L33, the non-zero-order diffracted light on the short axis side is blocked by the short axis side light shield 236. 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 or higher. As shown in Figure 6, the non-zero-order diffracted light on the short axis side is irradiated into an irradiation area 81 that is elongated in the long axis direction, both above and below the aperture 236a of the short axis side light shield 236a (i.e., on both sides of the short axis direction of the aperture 236a).

[0060] As shown in Figures 4 and 5, the cross-section of the modulated beam L33 that has passed through the aperture 236a of the short-axis side light-shielding portion 236 widens in the short-axis direction as it travels in the direction of propagation 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. In the long-axis direction, the modulated beam L33 does not refract when passing through the third lens 233, but is focused after passing through the first lens 231 and concentrated at the rear focal position of the first lens 231 (i.e., the front focal position of the second lens 232).

[0061] As described above, a long-axis side light-shielding section 235 is positioned at the focal point on the long axis side of the modulated beam L33 by the first lens 231 (i.e., the rear focal point of the first lens 231). The modulated beam L33 that has passed through the first lens 231 passes through the aperture 235a of the long-axis side light-shielding section 235. Specifically, of the modulated beam L33, which is the reflected light reflected by the optical modulator 22, the 0th-order light passes through the aperture 235a of the long-axis side light-shielding section 235. The cross-sectional shape of the modulated beam L33 passing through the aperture 235a of the long-axis side light-shielding section 235 is approximately straight or approximately rectangular, elongated in the short axis direction. The intensity distribution of the modulated beam L33 passing through the aperture 235a of the long-axis side light-shielding section 235 is a sinc distribution in the long axis direction and a top-hat distribution in the short axis direction, as shown enclosed in a rectangular frame below the optical path diagrams in Figures 4 and 5.

[0062] On the other hand, of the modulated beam L33, the non-zero-order diffracted light on the long axis side (mainly the first-order diffracted light) is blocked by the long axis side light shield 235. As shown in Figure 7, the non-zero-order diffracted light on the long axis side is irradiated into a substantially linear or substantially rectangular irradiation area 82 extending in the short axis direction, at the left and right sides of the aperture 235a of the long axis side light shield 235 (i.e., both sides of the aperture 235a in the long axis direction).

[0063] As shown in Figures 4 and 5, the cross-section of the modulated beam L33 that has passed through the aperture 235a of the long-axis side light-shielding portion 235 widens in the long axis direction as it travels in the direction of propagation of the modulated beam L33, and becomes parallel light in the long axis direction after passing through the second lens 232. Furthermore, the modulated beam L33 that has entered the second lens 232 as parallel light in the short axis direction is focused in the short axis direction after passing through the second lens 232, and is concentrated in the short axis direction on the illumination surface 134 of the scanning unit 13 located at the rear focal position of the second lens 232.

[0064] The cross-sectional shape of the modulated beam L33 on the irradiation surface 134 of the scanning unit 13 is a roughly rectangular shape that is elongated in the long axis direction. The intensity distribution of the modulated beam L33 on the irradiation surface 134 of the scanning unit 13 is a top-hat distribution in the long axis direction and a sinc distribution in the short axis direction, as shown enclosed in a rectangular frame below the optical path diagrams in Figures 4 and 5. Since the sinc distribution has a main peak, similar to a Gaussian distribution, the modulated beam L33 can be suitably focused onto the irradiation surface 134 of the scanning unit 13.

[0065] In the 3D fabrication apparatus 1 shown in Figure 1, as described above, a modulated beam L33, suitably focused on the irradiation surface 134, is scanned by the scanning unit 13 over the fabrication material 91 in the fabrication space 140. A 3D fabricated object is formed by repeatedly supplying the fabrication material 91 to the fabrication space 140 and scanning the laser beam over the fabrication material 91.

[0066] Next, an example of the specific size of the cross-section of the shaping beam L32 and the modulated beam L33 in the optical device 12 will be described. In this example, the wavelength λ of the laser light L31 emitted from the laser light source 11 is 1.070 μm, and the diameter of the approximately circular cross-section of the collimated beam L321 incident on the beam shaper 213 in the illumination optical system 21 is (1 / e 2 The width is 5 mm. The paraxial focal length f on the long axis side of the beam shaper 213. x It is -46mm, and the paraxial focal length f on the minor axis side yThe length is -1250 mm. The paraxial focal length f0 of the convex lens 214 is 250 mm. The distance L1 between the beam shaper 213 and the convex lens 214 is approximately 204 mm, and the distance L2 between the convex lens 214 and the modulation surface 224 of the optical modulator 22 is equal to f0. In this case, the irradiation area of ​​the shaped beam L32 on the modulation surface 224 is roughly rectangular, with a length of approximately 27 mm in the long axis direction and a length of approximately 1 mm in the short axis direction. As described above, the shaped beam L32 incident on the optical modulator 22 is parallel light in the long axis direction and converged light in the short axis direction.

[0067] The combined focal length of the beam shaper 213 and the convex lens 214 on the minor axis side (i.e., f y The combined focal length of f0 is approximately 260 mm, and the focusing position on the short-axis side of the shaping beam L32 incident on the optical modulator 22 (i.e., the position where the short-axis side light-shielding portion 236 is located) is approximately 52 mm away from the modulation surface 224 of the optical modulator 22 (i.e., towards the projection optical system 23). The numerical aperture NA forming this focusing position is 0.01, and the focusing diameter in the short-axis direction of the modulated beam L33 at this focusing position (i.e., the dark ring diameter of the sinc function) is approximately 130 μm.

[0068] In the projection optical system 23, the paraxial focal length f3 of the third lens 233 is 158 mm, the paraxial focal length f1 of the first lens 231 is 240 mm, and the paraxial focal length 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 length of the third lens 233 and the first lens 231 on the minor axis side (i.e., the combined focal length of f3 and f1) is approximately 136 mm. From the ratio of this combined focal length to the paraxial focal length f2 of the second lens 232, the focusing diameter in the minor axis direction of the modulated beam L33 on the illumination surface 134 of the scanning unit 13 (i.e., the dark ring diameter of the sinc function) is approximately 57 μm, which is approximately 0.44 times the focusing diameter in the minor axis direction of the modulated beam L33 at the aforementioned focusing position (approximately 130 μm). Furthermore, the length of the modulated beam L33 in the long axis direction on the illumination surface 134 of the scanning unit 13 is approximately 6.74 mm, which is about 0.25 times the length of the shaping beam L32 in the long axis direction on the modulation surface 224 of the optical modulator 22, based on the ratio of the paraxial focal length f1 of the first lens 231 to the paraxial focal length f2 of the second lens 232.

[0069] The pitch of the pixels 221 in the optical modulator 22 in the long axis and short axis directions is 25.5 μm, and the angle of the first diffracted light relative to the 0th order light is approximately 42 mrad (milliradians). Therefore, in the short axis side light shielding portion 236, the distance in the short axis direction between the 0th order light and the first diffracted light is approximately 2.2 mm. In the long axis side light shielding portion 235, the distance in the long axis direction between the 0th order light and the first diffracted light is approximately 10 mm.

[0070] As shown in Figure 3, in the optical device 12, the illumination optical system 21 is positioned obliquely to the modulation surface 224 of the optical modulator 22, and the convex lens 214, which is the rear end of the illumination optical system 21, faces the modulation surface 224 of the optical modulator 22. The optical axis J2 of the illumination optical system 21 is inclined with respect to the normal direction of the modulation surface 224 of the optical modulator 22, and the shaped beam L32 emitted from the illumination optical system 21 toward the optical modulator 22 is incident obliquely to the modulation surface 224 of the optical modulator 22 at a predetermined incidence angle greater than 0°.

[0071] Furthermore, in the optical device 12, the projection optical system 23 is also positioned obliquely to the modulation surface 224 of the optical modulator 22, and the short-axis side light-shielding portion 236, which is the front end of the projection optical system 23, faces the modulation surface 224 of the optical modulator 22. The optical axis J3 of the projection optical system 23 is inclined with respect to the normal direction of the modulation surface 224 of the optical modulator 22, and the modulated beam L33, which is modulated and reflected at the modulation surface 224 of the optical modulator 22, is incident on the projection optical system 23 along the optical axis J3 of the projection optical system 23. Note that the reflection angle of the modulated beam L33 at the modulation surface 224 of the optical modulator 22 (which can also be considered as the reflection angle of the shaping beam L32) is greater than 0°.

[0072] 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 components of the illumination optical system 21, such as the convex lens 214, and the components of the projection optical system 23, such as the short-axis side light-shielding part 236, are separated in the vertical direction in Figure 3, and mechanical interference between the illumination optical system 21 and the projection optical system 23 is suppressed. As a result, the components of the convex lens 214 can be brought closer to the optical modulator 22 in the direction of the optical axis J2, and the components of the short-axis side light-shielding part 236 can be brought closer to the optical modulator 22 in the direction of the optical axis J3. This makes the optical device 12 smaller in the left-right direction in Figure 3. On the other hand, as the angle θ increases, the size of the optical device 12 in the vertical direction increases.

[0073] Furthermore, as the angle θ decreases, the illumination optical system 21 and the projection optical system 23 move closer together in the vertical direction in Figure 3, allowing the optical device 12 to be miniaturized in that vertical direction. On the other hand, as the angle θ decreases, the components of the illumination optical system 21, such as the convex lens 214, and the components of the projection optical system 23, such as the short-axis light-shielding portion 236, move closer together in the vertical direction in Figure 3. Therefore, in order to suppress mechanical interference between the illumination optical system 21 and the projection optical system 23, it is necessary to separate the components of the illumination optical system 214, such as the convex lens 214, from the optical modulator 22 in the direction of the optical axis J2, and separate the components of the short-axis light-shielding portion 236, such as the short-axis light-shielding portion 236, from the optical modulator 22 in the direction of the optical axis J3. As a result, the size of the optical device 12 in the left-right direction increases.

[0074] In order to achieve both miniaturization of the optical device 12 in the left-right direction and in the up-down direction as shown in Figure 3, 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, and more preferably 10° or more and 20° or less.

[0075] As described above, the optical device 12 is a device that irradiates a modulated beam L33 onto an object (in the above example, the scanning unit 13). The optical device 12 comprises an illumination optical system 21, an optical modulator 22, and a projection optical system 23. The illumination optical system 21 shapes the laser light L31 into a long, shaped beam L32 in the longitudinal direction. The optical modulator 22 modulates the shaped beam L32 into a modulated beam L33. The projection optical system 23 guides the modulated beam L33 to the irradiation surface 134 of the object. The illumination optical system 21 comprises a beam shaper 213 and an illumination optical element 214 (in the above example, a convex lens 214). The illumination optical system 21 is configured to convert the intensity distribution in the longitudinal direction of the incident light from a Gaussian distribution to a top-hat distribution for the intensity distribution in the longitudinal direction of the shaped beam L32 at the modulation surface 224 of the optical modulator 22. Furthermore, the illumination optical system 21 is configured to guide the incident light to the optical modulator 22 as parallel light in the long axis direction and as converged light in the short axis direction. The optical modulator 22 comprises a plurality of modulation elements (pixels 221 in the above example) arranged in two dimensions, and performs modulation in the long axis direction but not in the short axis direction.

[0076] The projection optical system 23 comprises a short-axis side light-shielding section 236, a first projection optical element 231 (first lens 231 in the above example), a long-axis side light-shielding section 235, and a second projection optical element 232 (second lens 232 in the above example). The short-axis side light-shielding section 236 is positioned at the focusing position on the short axis side of the modulated beam L33, which is emitted from the optical modulator 22 and whose short-axis side is focused light, and blocks the non-zero-order diffracted light on the short axis side of the modulated beam L33. The first projection optical element 231 focuses the modulated beam L33 that has passed through the short-axis side light-shielding section 236 in the long axis direction. The long-axis side light-shielding section 235 is positioned at the focusing position on the long axis side of the modulated beam L33 by the first projection optical element 231 and blocks the non-zero-order diffracted light on the long axis side of the modulated beam L33. The second projection optical element 232 focuses the modulated beam L33, which has passed through the long-axis light-shielding portion 235, in the short-axis direction and concentrates it onto the illumination surface 134. The projection optical system 23 makes the modulated surface 224 and the illumination surface 134 optically conjugate in the long-axis direction.

[0077] Thus, in the optical device 12, the intensity distribution in the longitudinal direction of the laser light L31 is made into a top-hat distribution by the illumination optical system 21 equipped with a beam shaper 213 and illumination optical element 214, thereby increasing the total amount of light input while reducing the maximum power density of the shaped beam L32 incident on the optical modulator 22. Furthermore, in the optical device 12, there is no need to provide an optical element in the projection optical system 23 to focus the modulated beam L33, which has been modulated by the optical modulator 22, toward the short-axis side light-shielding portion 236, thus reducing the number of optical elements such as lenses that constitute the projection optical system 23. In other words, the optical device 12 can increase the amount of light input to the optical modulator 22 while simplifying the structure of the projection optical system 23. Moreover, in the optical device 12, the modulation surface 224 of the optical modulator 22 and the irradiation surface 134 of the object are optically conjugate in the longitudinal direction, so the modulation of light on the modulation surface 224 can be accurately reflected on the irradiation surface 134.

[0078] 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 third projection optical element 233 and the first projection optical element 231 make the modulated beam L33 that has passed through the short-axis side light-shielding portion 236 parallel in the short-axis direction. The first projection optical element 231 has the same focal position in the short-axis direction as in the long-axis direction. Preferably, the projection optical system 23 makes the short-axis side light-shielding portion 236 and the irradiation surface 134 of the object optically conjugate in the short-axis direction. This allows the modulated beam L33 to be suitably focused in the short-axis direction on the irradiation surface 134 of the object. As a result, the power density of the modulated beam L33 irradiated onto the object can be suitably increased.

[0079] As described above, it is preferable that the illumination optical system 21 converts the intensity distribution of the laser beam L31 in the short axis direction from a Gaussian distribution to a top-hat distribution, thereby also making the intensity distribution of the shaped beam L32 in the short axis direction at the modulation plane 224 a top-hat distribution. This makes it possible to further increase the total input light amount while reducing the maximum power density of the shaped beam L32 incident on the optical modulator 22. In other words, it is possible to further increase the amount of light input to the optical modulator 22.

[0080] As described above, it is preferable that the illumination optical element 214 is a single lens (a convex lens 214 in the above example). Furthermore, it is preferable that no optical elements other than the single lens are placed between the beam shaper 213 and the light modulator 22 in the illumination optical system 21. This simplifies the structure of the illumination optical system 21. As a result, the degree of freedom in the arrangement of the illumination optical system 21 can be improved, and the optical device 12 can be miniaturized.

[0081] As described above, it is preferable that the modulated beam L33 emitted from the optical modulator 22 directly enters the short-axis 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 arranging the projection optical system 23 can be improved, and the optical device 12 can be miniaturized.

[0082] As mentioned above, the optical modulator 22 is preferably a PLV. Because PLVs have high power handling performance, they are particularly suitable for the optical modulator 22 where an increase in the input light amount is required.

[0083] As described above, it is preferable that the beam shaper 213 is a single optical element that spreads the incident light at different divergence angles in the long axis direction and the short axis direction. This makes it possible to generate a shaped beam L32 having a cross-sectional shape that is long in the long axis direction while simplifying the structure of the illumination optical system 21. As a result, the optical device 12 can be further miniaturized. The beam shaper 213 may also focus the incident light in the short axis direction.

[0084] In the optical device 12, it is preferable that the shaped beam L32 emitted from the illumination optical system 21 is incident obliquely on the modulation surface 224 at a predetermined incident angle, and the modulated beam L33, which is modulated and reflected on the modulation surface 224, is incident on the projection optical system 23. As described above, since the structure of the projection optical system 23 is simplified in the optical device 12, the optical device 12 with the above structure, in which the illumination optical system 21 and the projection optical system 23 are aligned at a position facing the modulation surface 224, can be miniaturized in the direction in which the illumination optical system 21 and the projection optical system 23 are aligned (i.e., the vertical direction in Figures 1 and 3).

[0085] The 3D printing apparatus 1 comprises the optical device 12 described above, a laser light source 11, and a scanning unit 13. The laser light source 11 emits laser light L31 to the optical device 12. The scanning unit 13 is the object to which the modulated beam L33 from the optical device 12 is irradiated, and it scans the modulated beam L33 on the printing material. As described above, the optical device 12 can suitably increase the power density of the modulated beam L33 irradiated onto the object (i.e., the scanning unit 13), and therefore, in the 3D printing apparatus 1, the power density of the modulated beam L33 irradiated onto the printing material 91 can also be suitably increased. As a result, the printing speed of the printed object in the 3D printing apparatus 1 can be increased, and productivity can be improved. Furthermore, as described above, the optical device 12 can be miniaturized by simplifying the structure of the projection optical system 23, and thus the 3D printing apparatus 1 can also be miniaturized.

[0086] As described above, it is preferable that the scanning unit 13 includes a galvanometer mirror 133 that changes the direction of travel of the modulated beam L33 by rotating. This enables high-precision and high-speed scanning of the modulated beam L33 from the optical device 12.

[0087] In the 3D printing apparatus 1, as described above, it is preferable that the scanning direction of the modulated beam L33 by the scanning unit 13 corresponds to the direction of the short axis of the modulated beam L33. On the printing material 91, the intensity distribution in the short axis direction of the modulated beam L33 is a sinc distribution, so a bright ring exists around the focal point, and the region in front of the focal point in the scanning direction (i.e., in the short axis direction) is preheated by this bright ring. Therefore, when scanning the preheated region with the modulated beam L33, the heating time of the region can be shortened. As a result, the productivity of the 3D printing apparatus 1 can be further improved.

[0088] Various modifications are possible to the optical device 12 and the 3D printing device 1 described above.

[0089] For example, the arrangement of the illumination optical system 21, the optical modulator 22, and the projection optical system 23 is not limited to those shown in Figures 1 and 3, and can be changed in various ways. For example, the shaping beam L32 emitted from the illumination optical system 21 does not necessarily have to be incident at an oblique angle to the modulation plane 224 of the optical modulator 22, but may be incident approximately perpendicularly.

[0090] The optical modulator 22 is not necessarily limited to LPLV, and may be a PLV other than LPLV. In addition, other types of optical modulators besides PLV, such as GLV (Grating Light Valve) (registered trademark) and DMD (Digital Micromirror Device), can also be used as the optical modulator 22.

[0091] The divergence angles of the incident light by the beam shaper 213 do not necessarily have to be different in the long axis and short axis directions; they may be the same in both directions. Furthermore, the beam shaper 213 does not necessarily have to be composed of only one optical element; it may be composed of multiple optical elements. The beam shaper 213 is not necessarily limited to an aspherical concave lens; for example, it may 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 light L31 in the short axis direction does not necessarily have to be converted to a top-hat distribution.

[0092] In the illumination optical system 21, the illumination optical element 214 does not necessarily have to be a convex lens, but may be other optical elements. Also, the illumination optical element 214 does not necessarily have to be composed of only one optical element, but may be composed of multiple optical elements. In the illumination optical system 21, other optical elements may be placed between the beam shaper 213 and the light modulator 22 in addition to the illumination optical element 214.

[0093] In the projection optical system 23, an optical element may be placed between the light modulator 22 and the short-axis light-shielding portion 236. In this case, the modulated beam L33 emitted from the light modulator 22 enters the short-axis light-shielding portion 236 via the optical element.

[0094] 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, but may each be composed of two or more optical elements, for example. In addition, 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-shielding portion 235 and the short-axis side light-shielding portion 236 of the projection optical system 23 are not limited to those described above and may be modified in various ways.

[0095] In the optical device 12, the short-axis light-shielding portion 236 and the irradiation surface 134 do not necessarily have to be optically conjugate with respect to the short axis. For example, the irradiation surface 134 may be slightly offset from the position where it is conjugate with respect to the short-axis light-shielding portion 236.

[0096] In the scanning unit 13 of the 3D printing apparatus 1, a scanning mechanism with a different structure, such as a polygon laser scanner, may be provided instead of the galvanometer scanner 132. Alternatively, the scanning unit 13 is not limited to changing the direction of travel of the modulated beam L33 from the projection optical system 23, but may also be a moving mechanism such as a linear motor that moves the printing unit 141, which holds the printing material 91 while the irradiation position of the modulated beam L33 is fixed, in the horizontal direction.

[0097] The optical device 12 does not necessarily have to be installed in the 3D printing device 1; for example, it may be used in a laser processing machine such as a laser marking device.

[0098] The configurations in the above embodiments and each modified example may be combined as appropriate, as long as they do not contradict each other. [Explanation of Symbols]

[0099] 1 3D printing equipment 11 Laser light source 12 Optical equipment 13 Scanning Unit 21 Illumination optical system 22 Optical modulators 23 Projection optical system 91 Modeling Materials 133 Galvano Mirror 134 Irradiation surface 213 Beam Shaper 214 Illumination optical elements 221 pixels (modulation element) 224 Modulation plane 231 First projection optical element 232 Second projection optics element 235 Long axis side light shielding part 236 Short axis side light shielding part L31 Laser Light L32 Shaping Beam L33 Modulated Beam

Claims

1. An optical device that irradiates a modulated beam onto an object, An illumination optical system that shapes laser light into a long, shaped beam along its long axis, A light modulator that modulates the shaping beam into a modulated beam, A projection optical system that guides the modulated beam to the irradiation surface of the object, Equipped with, The illumination optical system is Beam shaper and, Illumination optical element, Equipped with, The illumination optical system is configured to convert the intensity distribution of the incident light in the longitudinal direction from a Gaussian distribution to a top-hat distribution for the intensity distribution of the shaped beam in the longitudinal direction on the modulation plane of the optical modulator, and to guide the incident light to the optical modulator as parallel light in the longitudinal direction and converged light in the short direction. The optical modulator comprises a plurality of modulation elements arranged in a two-dimensional array, and performs modulation in the long axis direction but does not perform modulation in the short axis direction. The aforementioned projection optical system is A short-axis side light-shielding portion is positioned at the focusing position on the short-axis side of the modulated beam, whose short-axis side is focused light emitted from the optical modulator, and blocks the non-zero-order diffracted light on the short-axis side of the modulated beam. A first projection optical element that focuses the modulated beam that has passed through the short-axis side light-shielding portion in the long-axis direction, A long-axis side light-shielding portion is positioned at the focal point on the long axis side of the modulated beam by the first projection optical element and blocks non-zero-order diffracted light on the long axis side of the modulated beam, A second projection optical element that focuses the modulated beam, which has passed through the long-axis light-shielding portion, in the short-axis direction and concentrates it on the irradiation surface, Equipped with, An optical device characterized in that the modulation surface and the illumination surface are optically conjugate with respect to the long axis direction by the projection optical system.

2. The optical apparatus according to claim 1, The projection optical system further comprises a third projection optical element located between the short-axis light-shielding portion and the first projection optical element. The third projection optical element and the first projection optical element cause the modulated beam that has passed through the short-axis side light-shielding portion to become parallel light in the short axis direction. The first projection optical element has the same focal position in the direction of the long axis as in the direction of the short axis, An optical device characterized in that, by the projection optical system, the short-axis side light-shielding portion and the illumination surface are optically conjugate with respect to the short axis direction.

3. The optical apparatus according to claim 1, The illumination optical system is characterized in that, by converting the intensity distribution of the laser light in the short axis direction from a Gaussian distribution, the intensity distribution of the shaping beam in the short axis direction on the modulation plane is also made to a top-hat distribution.

4. An optical apparatus according to any one of claims 1 to 3, The illumination optical element is a single lens, The optical device is characterized in that, in the illumination optical system, no optical elements other than the one lens are arranged between the beam shaper and the light modulator.

5. An optical apparatus according to any one of claims 1 to 3, An optical device characterized in that the modulated beam emitted from the optical modulator is directly incident on the short-axis light-shielding portion without passing through other optical elements.

6. An optical apparatus according to any one of claims 1 to 3, The optical device is characterized in that the optical modulator is a PLV.

7. An optical apparatus according to any one of claims 1 to 3, The optical device is characterized in that the beam shaper is a single optical element that spreads the incident light at different divergence angles in the long axis direction and the short axis direction.

8. An optical apparatus according to any one of claims 1 to 3, An optical device characterized in that the shaping beam emitted from the illumination optical system is incident obliquely on the modulation surface at a predetermined incident angle, and the modulated beam, which is modulated and reflected by the modulation surface, is incident on the projection optical system.

9. It is a 3D modeling device, An optical apparatus according to any one of claims 1 to 3, A laser light source that emits the laser light to the optical device, The object to which the modulated beam from the optical device is irradiated, and comprising a scanning unit that scans the modulated beam on the molding material, A three-dimensional molding apparatus characterized by comprising the following features.

10. A three-dimensional molding apparatus according to claim 9, The scanning unit is characterized by comprising a galvanometer mirror that rotates to change the direction of propagation of the modulated beam, thereby forming a three-dimensional molding apparatus.

Images