Laser irradiation device, molding device, and laser irradiation method

Abstract

To efficiently irradiate an irradiation target region with laser.SOLUTION: A laser irradiation device 100 comprises: a plurality of AODs that deflect laser light; and a galvano-scanner 30 that deflects the laser light on the downstream side of the AODs. As the AODs, at least a first AOD 21 and a first AOD 22 are provided. Laser light that is raster-scanned by deflection with the galvano-scanner 30 is further deflected by either the first AOD 21 or the first AOD 22 and an unirradiated region is irradiated with the laser light. At least one of a case where the laser light is deflected only by the first AOD 21 and a case where the laser light is deflected only by the first AOD 22 is included.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a laser irradiation device, a modeling device, and a laser irradiation method. Regarding. [Background technology]

[0002] As a method for irradiating a target area of an object with laser light, raster scanning laser light irradiation is generally known.

[0003] For irradiation patterns with many complex structures, such as character strings, raster scanning, which has a high scanning speed, can shorten the time required for a series of laser irradiation operations, which has a certain effect on improving the productivity of laser irradiation devices.However, with raster scanning, the laser is turned off in non-irradiated areas, resulting in wasted scanning time, so there is room for improvement in terms of productivity.

[0004] Such a laser irradiation device also has a deflector that deflects the laser light. By deflecting the zero-order light emitted from the light source with the deflector, the laser light can be irradiated at a desired position, such as for raster scanning.

[0005] As a deflector for deflecting the above-described laser light, for example, Patent Document 1 (JP 2012-528011 A) describes an AOD system that deflects laser light in a first direction and a galvano system that deflects it in a second direction. Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to efficiently irradiate a target region with a laser. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a laser irradiation device comprising a plurality of upstream deflectors that deflect laser light, and a downstream deflector that deflects the laser light downstream of the upstream deflectors, wherein the upstream deflectors include at least a first upstream deflector and a second upstream deflector, and the laser light that is raster scanned by deflection by the downstream deflector is deflected by the first upstream deflector or the second upstream deflector to be irradiated onto an unirradiated area, and the present invention is characterized in that the laser irradiation device includes at least one of a case where the laser light is deflected only by the first upstream deflector of the first upstream deflector and the second upstream deflector, and a case where the laser light is deflected only by the second upstream deflector. [Effects of the Invention]

[0008] According to the present invention, the irradiation target area can be efficiently irradiated with laser. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 10 is a plan view showing a laser irradiation device different from the embodiment of the present invention. [Figure 2] FIG. 2 is a flow diagram of marking with laser light using the laser irradiation device of FIG. [Figure 3] 1 is a diagram showing the raster scanning trajectory of a galvanometer scanner and the deflection direction of an acousto-optic deflector (AOD). [Figure 4] Figure (a) shows the image pattern to be marked, Figure (b) shows a conventional marking method for marking the image pattern, and Figures (c) and (d) show a marking method using the laser irradiation device of Figure 2. [Figure 5] 1A and 1B are diagrams showing the configuration of a laser irradiation device according to a first embodiment of the present invention, in which FIG. 1A is a diagram viewed from the -y direction to the +y direction, and FIG. 1B is a diagram viewed from the +x direction to the -x direction. [Figure 6] Figure (a) shows an example of the installation of the first AOD, Figure (b) shows an example of the installation of the second AOD, and Figure (c) shows the deflection area at the installation positions of Figures (a) and (b). [Figure 7] FIG. 1(a) is a diagram showing an image pattern to be marked, FIG. 1(b) is a diagram showing an area that can be irradiated with zero-order light by the laser irradiation device of the first embodiment, and FIG. 1(c) is a diagram showing an example of a marking method. [Figure 8] FIG. 2(a) is a diagram showing an area that can be irradiated with zero-order light by the laser irradiation device of FIG. 1, and FIG. 2(b) is a diagram showing an example of a marking method. [Figure 9] FIG. 1(a) is a diagram showing the relationship between the deflection direction of the first AOD and the pixel size, and FIG. 1(b) is a diagram showing the relationship between the deflection direction of the first AOD and the second AOD and the pixel size. [Figure 10] 10A to 10D are diagrams showing deflection directions passing through the pixel centers for pixels of different sizes. [Figure 11] FIG. 10 is a diagram showing deviation from the pixel center depending on the deflection direction of the AOD. [Figure 12] 10 is a diagram showing a case where both a deviation from the pixel center due to the deflection direction of each AOD and a deviation from the image center due to the distance between the two deflection directions of the first AOD and the second AOD occur. FIG. [Figure 13] 10A and 10B are diagrams illustrating multiple irradiations of laser light in an acceleration / deceleration region. [Figure 14] FIG. 10 is a diagram illustrating a case where two pixels are marked while one pixel is passed by the galvanometer scanner during main scanning. [Figure 15] FIG. 2 is a block diagram showing a control unit of the laser irradiation device. [Figure 16] FIG. 1(a) is a diagram showing an example of marking, and FIG. 1(b) is a diagram showing a timing chart of the control of the first AOD for the marking of FIG. 1(a). [Figure 17] 10A and 10B are diagrams showing other embodiments in which the deflection directions of the first and second AODs are different. [Figure 18] FIG. 10 shows the deflectable regions in an embodiment of a laser irradiation device having three AODs. [Figure 19] FIG. 19 shows the deflectable regions in an embodiment of the laser irradiation device different from that of FIG. 18, which has three AODs. [Figure 20] FIG. 10 is a diagram showing the deflection distance by the first AOD. [Figure 21] FIG. 1 illustrates a powder bed fusion apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and redundant explanations will be appropriately simplified or omitted.

[0011] ●Laser irradiation device 1 shows a plan view of a laser irradiation device 200 different from the embodiments of the present invention. This laser irradiation device 200 includes a laser oscillator 10 as a light source, an acousto-optic deflector 20 as an upstream deflector, a galvanometer scanner 30 as a downstream deflector, and an fθ lens 40. Hereinafter, the acousto-optic deflector will be referred to as an "AOD" (Acousto-Optic Deflector). The laser irradiation device 200 differs particularly from the laser irradiation devices of the embodiments of the present invention described below in that it includes only one AOD.

[0012] The AOD 20 includes a piezoelectric transducer coupled to the crystal and a radio frequency (RF) driver that drives the piezoelectric transducer, generating RF frequency acoustic waves within the crystal, e.g., acoustic waves in a frequency range between about 50 MHz and about 1500 MHz.

[0013] The incident laser light is diffracted by the acoustic waves generated in the crystal in proportion to the RF frequency, and a portion of the input beam power is deflected as first-order light (diffracted light) A1.

[0014] The laser light emitted from the laser irradiation device 200 is deflected by the AOD 20, and the first-order light (diffracted light) A1 thereof is incident on the galvano scanner 30. The laser light incident on the galvano scanner 30 is raster-scanned by the galvano scanner 30.

[0015] The raster-scanned laser light is incident on an fθ lens 40, which is a condenser lens. The laser light emitted from the fθ lens 40 is irradiated onto a marking object 50, which is an irradiation object, and forms a marking on the surface (or inside) of the marking object 50.

[0016] The fθ lens 40 is configured to focus the laser light scanned by the galvanometer scanner 30 onto the marking object 50. For example, the fθ lens 40 is configured to scan the laser light scanned by the galvanometer scanner 30 at a predetermined angle on the imaging surface of the marking object 50 at a predetermined pitch.

[0017] FIG. 2 shows the flow from when light (laser light) emitted from the laser oscillator 10 is incident on the marking target 50 to when the laser irradiation position is marked. Light emitted from the light source at S1 enters the AOD 20 at S2, and a portion of the light is diffracted at an angle corresponding to the wavelength of the incident light, the speed of sound in the AOD 20 crystal, and the RF signal frequency applied from the RF driver connected to the AOD 20, to become first-order light (diffracted light) A1. The component of the light incident on the AOD 20 that is not diffracted travels straight as zero-order light (transmitted light) A0 as shown in FIG. 1 and is blocked (terminated) by the beam damper 35. In FIG. 1, the zero-order light A0 is blocked by the beam damper 35, but in cases where the power of the zero-order light A0 is so low that the marking target 50 is not marked even when the zero-order light A0 is incident on the marking target 50, the zero-order light A0 does not necessarily need to be blocked.

[0018] The primary light A1 is incident on the galvanometer scanner 30 and deflected by the galvanometer scanner 30 (S3). The light deflected by the galvanometer scanner 30 is focused by the fθ lens 40 at a marking position on the marking object 50 that corresponds to the angle of incidence on the fθ lens (S4).

[0019] The surface of the marking location on the marking object 50 irradiated with the laser is scraped or modified by the laser, thereby forming a visible marking (S5).

[0020] The first-order light A1 diffracted by the AOD 20 is scanned by the galvanometer scanner 30, and the laser irradiation position on the marking object 50 is controlled by two means: the AOD 20 and the galvanometer scanner 30. If necessary, a beam diameter conversion element, a beam profile shaping element, a wave plate, etc. can be provided before or after the AOD 20 of the laser irradiation device 200 in FIG.

[0021] The laser oscillator 10 may be a pulsed laser with a wavelength of, for example, 355 nm, 532 nm, or 1064 nm. A pulsed laser is a type of laser whose laser output fluctuates over time. The pulse width is, for example, from several tens of femtoseconds to several hundreds of nanoseconds.

[0022] A CW (Continuous Wave) oscillation laser may be switched instead of a pulse oscillation laser as the laser oscillator 10. A CW oscillation laser is a type of laser in which the laser output does not change over time and remains constant.

[0023] The AOD20 is driven by an RF driver, and the first-order diffracted light propagates at an angle proportional to the RF frequency. Therefore, the deflection position of the AOD20 can be controlled by controlling the RF frequency.

[0024] The deflection control by the AOD 20 does not have inertia like the galvanometer scanner 30 or polygon scanner, and therefore the deflection control by the AOD 20 can deflect the laser light at high speed (for example, in a time of 5 us or less).

[0025] Furthermore, deflection control by the AOD 20 can provide a different deflection position for each pulse, even for a pulse laser with a high repetition rate (e.g., 200 kHz). In this embodiment, the AOD 20 is used as the deflection means, but the deflection means is not limited to this. The deflection means can be configured with any deflection means having a desired response speed. The upstream deflector may be an acousto-optical element such as the AOD 20, or an electro-optical element such as an electro-optical deflector (EOD) or a mirror optical deflector using a piezoelectric element (piezo element) capable of high-speed response.

[0026] As shown in Figure 3, in the following description, the sub-scanning direction in raster scanning by a galvanometer scanner is referred to as direction x, the main scanning direction as direction y, and in particular, the direction from upstream to downstream in raster scanning is referred to as the +x sub-scanning direction. With respect to raster scanning trajectory (raster scanning path) B, the laser light is deflected, for example, in the direction of arrow C by deflection by the AOD. The direction of arrow C is the deflection direction by the AOD. The angle between the +x direction and the line segment in the direction of arrow C is referred to as angle θ. In the example of Figure 3, the deflection direction of the AOD is the direction tilted from the +x direction to the +y direction by angle θ.

[0027] ● Marking of 4x5 pixel images A specific marking method and an embodiment that reduces the time required for marking will be described using the example of a simple image pattern in Figure 4. Consider marking a 4 x 5 pixel image as shown in Figure 4(a). Here, for simplicity, a small image size of 4 x 5 pixels is used, but the actual image size may be, for example, several hundred pixels x several hundred pixels, or even larger.

[0028] For convenience, let area H0 in Figure 4(b) have coordinates (1,1), the x coordinate of the (m-1)th column in the +x direction from area H0 be m, and the y coordinate of the (n-1)th row in the +y direction be n, and the coordinates of (x,y) = (m,n) will simply be written as (m,n). Pixels filled in with light ink are marking pixels (irradiated areas). White pixels are non-marking pixels (non-irradiated areas).

[0029] ● Conventional marking 4(b) shows the relationship between the scanning trajectory of the laser light and the laser irradiation position in a typical raster scan as a comparative example. The main scanning direction of the galvano scanner 30 is y, the sub-scanning direction is x, and the scanning direction is from -x to +x.

[0030] Main scanning refers to scanning in the column direction (±y direction), and sub-scanning refers to moving to the next column. In general raster scanning, all main scanning columns that contain at least one marking pixel are scanned. Therefore, in the example of Figure 4(b), marking of the marking pixel is completed after four main scanning passes.

[0031] For simplicity, unless otherwise specified, the laser light source is a pulsed laser, and one pixel is marked by one pulse irradiation.

[0032] Furthermore, the laser irradiation pitch (pitch [m] = galvanometer main scanning speed [m / s] / repetition frequency [1 / s]) calculated from the galvanometer main scanning speed and the laser repetition frequency is assumed to match the pixel size. However, if multiple pulse irradiations are required to mark one pixel, or if the light source is not a pulsed laser, or if the laser irradiation pitch and pixel size do not necessarily match, the present invention will still have the same effect.

[0033] Marking in this embodiment Figure 4(c) shows an example of a marking method using the laser irradiation device of Figure 2. In Figure 4(c), "scanning trajectory of laser light by galvanometer scanner (path of raster scanning by downstream deflector)" means the scanning trajectory of laser light generated by raster scanning of galvanometer scanner 30 when the deflection position of AOD 20 is maintained at a certain reference value.

[0034] The deflection direction of the laser light by the AOD 20 is set to the direction of θ=0 (+x direction). The x and y coordinates of the scanning trajectory of the laser light by the galvano scanner 30 at a certain point in time are set to x0 and y0, respectively.

[0035] The deviation of the x and y coordinates of the laser light due to the deflection position control of the AOD 20 is expressed as Δx and Δy (unit: pixel) relative to x0 and y0, respectively. For example, when x0 = 2 and Δx = 1, the x coordinate of the irradiation position of the laser light is 3. The maximum and minimum values of Δx are Δx_max and Δx_min, respectively, and the maximum and minimum values of Δy are Δy_max and Δy_min, respectively.

[0036] The scannable range of the AOD 20 on the marking object 50 (on the marking surface) is determined by the scanning angle of the AOD 20 and the fθ lens 40. The possible ranges of Δx and Δy are determined by the relationship between the scannable range of the AOD 20 and the pixel size.

[0037] For example, in this embodiment, the fθ lens focal length is 200 mm, the scanning field angle of the AOD 20 (the range of deflection positions that can be modulated) is 2 mrad, and the pixel size is 200 μm × 200 μm. In this case, the scannable range is 200 mm × 2 mrad = 400 μm.

[0038] Here, since θ=0, Δx_max−Δx_min and Δy_max−Δy_min are respectively Δx_max−Δx_min=400um×cos(θ) / 200um=2 and Δy_max−Δy_min=400um×sin(θ) / 200um=0. Also, Δy / Δx=tan(θ).

[0039] The scanning locus of the laser light by the galvano scanner 30 is set to the case where Δx is minimized (that is, Δx_min=0), and the pixel size is set to 200 μm×200 μm. In this case, Δx can be in the range of 0≦Δx≦2.

[0040] Table 1 shows the settings of x0, y0, and Δy in the marking method of FIG.

[0041] [Table 1]

[0042] The first row in the main scan scans the row x=1, just like in Figure 4(b). The (1,3) pixel is not a marking pixel but a non-marking pixel (non-irradiated area), and the (2,3) pixel is an unmarked pixel (unirradiated area of the irradiation target). Therefore, when the laser light scanning trajectory by raster scanning becomes (x0,y0)=(1,3), the deflection position of the AOD20 is controlled to make Δx=1, and the laser light, which was previously turned off, is turned on and irradiated at the position of the (2,3) pixel (unirradiated area).

[0043] Next, at the time when (x0, y0) = (1, 4), the (1, 4) pixel is a marking pixel, so the deflection position of the AOD 20 is controlled to set Δx = 0, and the (1, 4) pixel is irradiated with laser. Similarly, at (x0, y0) = (1, 5), the deflection position of the AOD 20 is controlled to set Δx = 1, and the laser light, which was previously turned off, is turned on, and the (2, 5) pixel (unirradiated area) is irradiated with laser.

[0044] Up to this point, one main scan is completed, and marking for two rows of x = 1, 2 is completed. Next, select row x0 = 3, for example, as the second main scan row, and set Δx to Δx = 1, 1, 0, 0, 1 for each of the galvano scanner scanning trajectory positions (x0, y0) = (3, 5), (3, 4), (3, 3), (3, 2), (3, 1), respectively.

[0045] By doing this, marking of the marking image in Figure 4(a) previously required four main scans, but can now be completed with just two. This reduction in the number of main scans (faster marking) is possible because a high-speed deflection scanning means such as the AOD20 can modulate the laser irradiation position for each pixel, making it possible to mark during times when the laser is turned off and marking is not possible with conventional general raster scanning.

[0046] In other words, by combining the galvanometer scanner 30 with the AOD 20, marking can be performed by instantaneous deflection scanning with the AOD 20 even at times when marking could not be performed by conventional general raster scanning using only the galvanometer scanner 30. This embodiment is particularly effective when it is desired to draw relatively sparse image patterns such as characters (which have a large margin for utilizing laser output) in a short time by high-speed marking using raster scanning.

[0047] In FIG. 4(c), x0=3 is set in the second main scan, but other scans such as x0=2 as shown in FIG. 4(d) are also possible.

[0048] Table 2 shows the settings of x0, y0, and Δy in the marking method of FIG.

[0049] [Table 2]

[0050] Figure 4(d) differs from Figure 4(c) in that the main scan for the second row is x=2. In Figure 4(d), Δx is set to Δx=2,2,1,1,2 for each of the scanning trajectory positions of the galvano scanner 30, (x0, y0)=(2,5), (2,4), (2,3), (2,2), and (2,1). The same effect can be obtained by scanning as in Figure 4(d).

[0051] As shown in Fig. 4(d), the deflection position of the laser light by the AOD 20, which is the first deflector, can be made different between the pth and p+qth raster scans at a predetermined coordinate in the raster scan direction (p and q are any integers). That is, for example, in Fig. 4(d), when (x0, y0) = (1, 5), Δx = 1, whereas when (x0, y0) = (2, 5), Δx = 2.

[0052] As such, there is more than one marking method that can achieve the same effect (faster marking). However, depending on the conditions of the fθ lens 40, etc., if there is a constraint that Δx≦1, marking as shown in Figure 4(d) is not possible, so the marking method shown in Figure 4(c) is preferable.

[0053] 5A and 5B are diagrams showing the configuration of a laser irradiation device according to a first embodiment of the present invention, in which (a) is a view from the -y direction to the +y direction, and (b) is a view from the +x direction to the -x direction. The following explanation will focus on the differences from the laser irradiation device 200 shown in FIG. 1 above.

[0054] 5(a) and 5(b), the laser irradiation device 100 includes a laser oscillator 10 as a light source, a first AOD 21 (first upstream deflector) and a second AOD 22 (second upstream deflector) as upstream deflectors, half-wave plates 23 and 24, a galvanometer scanner 30 as a downstream deflector, and an fθ lens 40. The direction of emission of the laser light is from the laser oscillator 10 toward the marking object 50, that is, the direction from left to right in FIG. 5 is the direction from upstream to downstream in the laser irradiation direction. The first AOD 21 and the second AOD 22 are disposed upstream of the galvanometer scanner 30.

[0055] The marking object 50, which is the irradiation object in this embodiment, is an object made of resin, such as a PET bottle. By irradiating the resin surface with laser light using the laser irradiation device 100, the surface is processed into a concave shape, and an image such as a letter is formed on the resin surface. However, the irradiation object of the present invention is not limited to this, and the purpose of laser light irradiation is not limited to forming an image or the like.

[0056] In this embodiment, the primary light D1 deflected by the first AOD 21 or the primary light D2 deflected by the second AOD 22 is deflected by the galvanometer scanner 30, enters the fθ lens 40, and is irradiated onto the marking target 50. The first AOD 21 and the second AOD 22 are never in the ON state at the same time. In other words, the first AOD 21 and the second AOD 22 do not deflect the same laser light, and the laser light passes through at least either the first AOD 21 or the second AOD 22 without being deflected. However, there may be cases where the laser light passes through both the first AOD 21 and the second AOD 22.

[0057] The half-wave plates 23 and 24 are disposed upstream of the first AOD 21 or the second AOD 22, respectively, and are used to align the polarization direction of the first AOD 21 or the second AOD 22.

[0058] The first AOD 21 and the second AOD 22 are arranged so as to deflect (diffract) the incident light in different directions, which makes it possible to deflect the laser light in different directions depending on which AOD is turned on.

[0059] Figure 6(a) shows an example of the installation of the first AOD, Figure 6(b) shows an example of the installation of the second AOD, and Figure 6(c) shows the deflectable area at the installation positions of Figure 6(a) and Figure 6(b).

[0060] As shown in Figure 6(a), the first AOD 21 is installed tilted from the +x direction to the -y direction (counterclockwise in Figure 6(a)) by the angle θ1 shown in Figure 6(a). Note that the clockwise direction is the positive direction of the angle θ, so the angle θ1 is a negative value. As shown in Figure 6(b), the second AOD 22 is installed tilted from the +x direction to the +y direction (clockwise in Figure 6(b)) by the angle θ2. These AODs deflect the incident laser light in the same direction even on their mirror surfaces.

[0061] 6(c), the region F1 that can be deflected by the first AOD 21 is a region in a direction tilted by an angle θ1 from the irradiation position E of the zero-order light (a region inclined counterclockwise by the absolute value of the angle θ1), and the region F2 that can be deflected by the second AOD 22 is a region in a direction tilted by an angle θ2 counterclockwise from the irradiation position E of the zero-order light. In this way, by providing two AODs, deflection regions can be provided in two directions, which increases the options compared to when there is only one AOD.

[0062] Here, because the AOD modulates the deflection direction by modulating the diffraction angle of the diffracted light, it cannot deflect light into a region below the minimum diffraction angle of the first-order light. Specifically, it cannot deflect light into the range from the irradiation position E of the zero-order light shown in Figure 6(c) to a distance L1. The deflection width of the first AOD 21 is indicated by a distance L2. Note that while Figure 6 shows a case where light is deflected toward the +x side, it can also be deflected toward the -x side. The relationship between the installation position of the AOD and the deflectable region on the image plane shown here is one example, and this relationship will change depending on the configuration of the optical system installed along the way, such as by rotating the image plane.

[0063] Next, an example of a marking method (laser irradiation method) using the laser irradiation device of this embodiment will be shown using Fig. 7. Fig. 7(a) is a diagram showing an image pattern to be marked, Fig. 7(b) is a diagram showing an area that the laser irradiation device can irradiate with zero-order light, and Fig. 7(c) is a diagram showing an example of a marking method using the laser irradiation device of the first embodiment. Note that the black circle in Fig. 7(b) indicates the case where laser light is irradiated at that position (when Δx and Δy = 0), and the same is true for Fig. 8(b).

[0064] The case of marking an image of 7 pixels x 18 pixels shown in FIG. 7(a) will be described. The entire region of 7 pixels x 18 pixels arranged in a grid pattern is the entire scanning region to be scanned by the laser irradiation device of this embodiment. Each pixel constituting this entire scanning region is also referred to as a "scanning target region." Each pixel (scanning target region) includes marking pixels (irradiation target region) that are to be irradiated with laser light and non-marking pixels (non-irradiation region) that are not to be irradiated with laser light. That is, the lightly shaded pixels in FIG. 7(a) are particularly unmarked pixels of the marking target pixels (particularly unirradiated regions of the irradiation target region). The white pixels are non-marked pixels (non-irradiation regions). The darkly shaded pixels in FIG. 7(b) are marked pixels of the marking target pixels (particularly irradiated regions of the irradiation target region). In Figure 7, the angle θ1 of the deflection direction of the first AOD 21 relative to the +x direction is -45°, the angle θ2 of the deflection direction of the second AOD 22 relative to the +x direction is 45°, the focal length of the fθ lens 40 is 150 mm, the angular range in which the first AOD 21 and the second AOD 22 can diffract is 2 mrad to 4 mrad, and the pixel size is 106 μm × 106 μm. Figure 7(b) shows the regions F1 and F2 on the image plane that can be irradiated by the first AOD 21 and the second AOD 22 relative to the zero-order light irradiation position E. The deflection range of the first AOD 21 and the second AOD 22 is 150 μm × 2 mrad = 300 μm, and the range in which Δx can be taken is 0≦Δx≦2.

[0065] If the leftmost deflection position by the first AOD is defined as point G(x0, y0), the seven pixels that can be irradiated by using three patterns: only the first AOD 21 is ON (the first AOD is ON and the second AOD is OFF), only the second AOD 22 is ON (the first AOD is OFF and the second AOD is ON), or both are OFF, are (x0, y0), (x0+1, y0-1), (x0+2, y0-2), (x0, y0+4), (x0+1, y0+5), (x0+1, y0+6), and (x0-2, x0+2). In this embodiment, point G is defined as the reference deflection position by the first AOD. This reference deflection position is the point where Δx = Δy = 0. Turning the AOD ON means that the AOD deflects the laser light, and turning the AOD OFF means that the AOD does not deflect the laser light.

[0066] Figure 7(c) shows marking when main scanning is performed on the column where x0=1. For convenience, the cross marks at the laser irradiation positions are omitted in Figure 7(c). The settings for x0, y0, Δx, Δy, x, and y in this case are shown in Table 3. Note that in this embodiment, the path of the raster scan by the galvano scanner passes through the center of the pixel, but the present invention is not necessarily limited to this.

[0067] [Table 3]

[0068] In the laser irradiation device of this embodiment, all three rows of marking pixels (x = 1 to 3) were successfully marked by main scanning within the range of 1≦y≦16 from x = 1. This was because one of the AODs deflected the zero-order light as it passed through the non-irradiated area of the raster scan, allowing the laser light to be irradiated onto the non-irradiated area. For example, a laser light moving through the area (x, y) = (1, 1) on the raster scan due to deflection by the galvanometer scanner can be deflected by the second AOD to irradiate the non-irradiated area (x, y) = (3, 7) with Δx = 2 and Δy = 6. This "position (area) on the raster scan" refers to the position through which the laser light passes when Δx = 0 and Δy = 0, and does not refer to all points on the raster scan trajectory. In other words, it refers to the position through which the laser light passes when the first AOD deflects the zero-order light to point G, which is the reference deflection position, and the second AOD is turned off. However, the reference deflection position is not necessarily limited to point G.

[0069] Next, as a comparative example, the case of marking the image pattern of Fig. 7(a) using the laser irradiation device of Fig. 1 will be described with reference to Fig. 8. Fig. 8(a) is a diagram showing an area that can be irradiated with zero-order light by the laser irradiation device of Fig. 1, and Fig. 8(b) is a diagram showing an example of a marking method.

[0070] As shown in FIG. 8(a), the laser irradiation device 200 of FIG. 1 is configured to have only one AOD 20, and therefore the deflectable region is also one of the regions F1.

[0071] Figure 8(b) shows marking when main scanning is performed on the column where x0=1. For simplicity, the cross marks at the laser irradiation positions are omitted in Figure 8(b). The settings for x0, y0, Δx, Δy, x, and y in this case are shown in Table 4. Note that a "-" in the x and y columns in Table 4 indicates that there are no pixels that can be marked.

[0072] [Table 4]

[0073] As shown in Figure 8(b), when the laser irradiation device of Figure 1 performs main scanning on the column x0=1, it is not possible to irradiate all of the marking pixels x=1 to x=3 with laser light, and marking pixel H1 remains as an unirradiated pixel. Therefore, while in the example of Figure 7(c) the column x0=4 can be selected as the second column, in Figure 8(b) the column x0=3, which has only one unirradiated pixel, must be selected as the second column, resulting in a difference in efficiency in marking the second column. This is due to the fact that there is only one AOD, which means there are fewer options for deflectable regions compared to the laser irradiation device of this embodiment of Figure 5.

[0074] As described above, the laser irradiation device of this embodiment deflects the laser beam from a raster scanning path using the AOD, thereby efficiently irradiating the target area on the irradiation target with the laser beam. In particular, in this embodiment, by providing multiple AODs as upstream deflectors, the number of possible deflection positions can be increased compared to the laser irradiation device 200 of FIG. 1, which uses a single upstream deflector. This enables efficient laser irradiation of the target area on the irradiation target, as shown by the comparison between FIG. 7(c) and FIG. 8(b) above. In particular, in the case of FIG. 8(a), where only one deflection direction is possible, irradiation of pixels aligned in this direction is impossible within the same main scanning row, making laser irradiation of pixels aligned in the deflection direction difficult. However, by providing multiple deflection directions using multiple upstream deflectors as in this embodiment, it is possible to irradiate pixels aligned in the same direction with laser beams using different deflection directions.

[0075] Specifically, the laser beam irradiation efficiency in the cases of Figure 7(c) and Figure 8(b) will be compared. If the laser pulse period is τ [s], in Figure 8(b), 14 pixels are irradiated over 18τ, while in Figure 7(c), 15 pixels are irradiated over 16τ. This means that the irradiation efficiency of this embodiment is approximately 16% better. Note that Figure 7(c) uses small pixels for convenience, so it is not possible to deflect the laser beam at positions y=17 and 18 to irradiate unirradiated areas of any of the target irradiation areas. However, if there are pixels beyond y=19, it may be possible to deflect the laser beam at positions y=17 and 18 to irradiate unirradiated areas. Furthermore, in such a large image, the pixels expand in the x direction, increasing the unirradiated area, resulting in a larger difference in irradiation efficiency between this embodiment and the laser irradiation device of Figure 1. Furthermore, when considering the irradiation efficiency from the second row onward, as described above, this embodiment has even better irradiation efficiency.

[0076] Alternatively, as a method different from the present embodiment, it is possible to simultaneously use the first AOD 21 and the second AOD 22 to create a two-dimensional deflection area. However, while this increases the number of deflection positions, it also has the adverse effect of reducing diffraction efficiency. In other words, if the diffraction efficiency of the AOD is approximately 80%, the first-order light in this embodiment has 80% of the energy of the zero-order light. However, when two AODs are used simultaneously, the energy decreases to 64% of the zero-order light. This can result in insufficient laser irradiation of the irradiation target, or in increased costs for the laser irradiation device in order to achieve sufficient laser irradiation. In this way, the laser irradiation device of this embodiment can achieve both highly efficient laser irradiation of the irradiation target and a sufficient amount of laser light energy.

[0077] When deflecting only in the +x direction, the x coordinate of the main scanning row for raster scanning is set to the smallest x coordinate in the unexposed area of the image of the irradiation object. For example, the second row in Figure 8(b) is at x=3. However, this does not apply when deflection in the -x direction is possible, and the x coordinate of the main scanning row for raster scanning can be determined so that it can be changed to the smallest x coordinate in the unexposed area of the image of the irradiation object.

[0078] Controlling the deflection position of an AOD is constrained by the response characteristics of the AOD element (such as the relationship between sound speed and beam diameter) and the response time imposed by the electrical characteristics of the control unit. If the pulse lighting interval of the laser light (the inverse of the repetition frequency) is T [s] and the time required to control the deflection position of the AOD is τ [s], then if T ≥ τ, the deflection position can be controlled independently for each laser pulse. In other words, since Δx and Δy can be set independently for each laser irradiation, there is a high degree of freedom, which is highly effective in speeding up marking. The time required to control the deflection position of the AOD is the time from irradiating a certain area with laser light to changing the deflection position to match the next area (i.e., changing Δx and Δy to match the next area).

[0079] When T<τ, the time required for deflection position control is longer than the pulse lighting interval. This makes it necessary to discard pulses during deflection position control (not lighting pulses at times when they can be turned on). In this case, it may be possible to achieve faster marking speeds by minimizing the number of times the deflection position is changed.

[0080] The deflection directions of the first AOD 21 and the second AOD 22 can be changed by changing the installation angle, etc. It is preferable to set the deflection direction to an angle that allows efficient image formation according to the irradiation pattern of the irradiation target. For example, if the angle θ' is the angle formed between the line segment with the longest length and the line segment parallel to the +x direction in the irradiation pattern on the xy coordinate plane of the irradiation target, it is preferable to set the deflection directions of the first AOD 21 and the second AOD 22 so that the angles θ1 and θ2 are different from the angles θ' and -θ'. As mentioned above, it is most difficult to deflect the laser light toward a line segment in the same direction as the deflection direction. Therefore, this setting allows efficient irradiation of the irradiation target area with laser light. For example, in the example of FIG. 7(a), the line segment with the longest length is a line segment parallel to the x direction, so it is preferable to set the angles θ1 and θ2 to values other than 0 degrees or 180 degrees.

[0081] Next, the relationship between the deflection position by the AOD and the pixel position will be explained using Figure 9. Figure 9(a) is a diagram showing the relationship between the deflection direction by the first AOD and the pixel size, and Figure 9(b) is a diagram showing the relationship between the deflection direction by the first AOD and the second AOD and the pixel size. The pixel size here refers to the width in the x direction and the y direction of one pixel (scanning area) on the xy coordinate system on the irradiation target.

[0082] As in the example of Figure 7, the focal length of the fθ lens was set to 150 mm, and the angular range in which the first and second AODs can diffract light was set to 2 mrad to 4 mrad. Here, as shown in Figure 9(a), if the pixel width in the x direction is Dx and the pixel width in the y direction is Dy, the deflection direction of the first AOD can be set to pass through the center of the pixel by satisfying the following formula (2). For example, if the pixel is square, that is, if Dy / Dx = 1, then formula (2) can be satisfied by setting θ1 = ±45 degrees or ±135 degrees. Also, in Figure 9(a), by setting Dx = 100 μm and Dy = 50 μm, and setting θ1 = ±arctan(50 / 100) = -0.464 rad, the deflection direction of the first AOD can pass through the center of the pixel, as shown in Figure 9(a). θ1=±arctan(Dy / Dx) (2)

[0083] As in Figure 6(c), by setting the angle θ2 = 0.464 rad that the deflection direction of the second AOD makes with respect to the +x direction, while keeping the absolute value the same, but changing the direction (reversing ±), the deflection direction of each AOD can be made symmetrical with respect to the 0th-order irradiation position E (the line segment in the X direction passing through it).

[0084] 9(b), the distance δ from point G at the left end of the deflection region F1 of the first AOD to point F2A at the left end of the deflection region F2 of the second AOD is 300 μm × sin(0.464 rad) × 2 = 269 μm, which is not an integer multiple of Dy. As a result, at least one of points G and F2A deviates from the center of the pixel.

[0085] To address this pixel misalignment, one method is to allow for deviation of the irradiation position from the pixel center. Another method is to select the deflection position not at the leftmost point G, F2A, but at a position to the right of that point where the distance δ is an integer multiple of Dy. In this case, part of the left side of the deflection area cannot be set as the deflection position, so depending on the relationship between the deflection distance L2 and the pixel size, the number of positions that can be changed may be limited. Another method is to change the pixel size. In the above example, if Dx = 107.6 μm and Dy = 53.8 μm, δ can be set to exactly 5 pixels. Another method is to select the x-coordinate of the laser light irradiation position so that the y-coordinate distance between the deflection areas of the first AOD and the second AOD is an integer multiple of Dy or a value close to it.

[0086] Fig. 10 shows the deflection direction passing through the pixel center for each pixel of different sizes in Figs. 1(a) to 1(d). Fig. 11 shows the deviation from the pixel center due to the deflection direction of the AOD. The dotted arrow in Fig. 11 indicates the deflection direction of the AOD. The same applies to subsequent Figs. 12 and so on.

[0087] Specifically, when point G is (m, n) = (0, 0), the angle θ (i.e., the deflection direction of the AOD) is set so that it passes through (m, n) = (1, 1), (2, 1), (1, 2), and (2, 3) in each of the diagrams (a) to (d). Specifically, the angle θ between the deflection direction of the AOD and the sub-scanning direction of the galvanometer scanner is set so as to satisfy the following equation (3). This allows the laser light to be deflected from point G on the trajectory of the raster scan by the galvanometer scanner to the pixel center at each of the above positions (m, n). Note that n and m are integers. θ=±arctan(n×Dy / m×Dx) (3)

[0088] Here, the angle θ can be adjusted not only by rotating the AOD deflection direction around the z-axis in Figure 5, but also by rotating the galvanometer scanner around the z-axis or by rotating the scanning direction of the galvanometer scanner without changing the optical system. Since the light incident on the AOD must have a specific polarization direction relative to the AOD, when the AOD is rotated, the polarization of the incident light must also be rotated accordingly using a half-wave plate or the like.

[0089] For example, when the angle θ1 = -arctan(Dy / (3Dx)) is used to deflect the laser beam from pixel (x0, y0) to the center of another pixel, the laser beam can only be deflected to a pixel represented by (x0 + 3k, y0 + k), where k is an integer. However, this limitation can be alleviated by allowing misalignment of the marking position. As shown in FIG. 11, if misalignment is not allowed, the laser beam can only be deflected to points G and F3C. However, by allowing a misalignment of Dy / 3 in the y direction (Dy is the y-direction pixel size), the laser beam from pixel (x0, y0) can also be deflected to pixels represented by (x0 + 3k-2, y0 + k-1) and (x0 + 3k-1, y0 + k) (k is an integer). In other words, the laser beam can also be deflected to points F3A and F3B.

[0090] FIG. 12 is a diagram showing a case where both a deviation from the pixel center due to the deflection direction of the AOD and a deviation from the image center due to the distance between the two deflection directions of the first AOD and the second AOD occur.

[0091] As shown in FIG. 12, there are cases where both the offset from the pixel center due to the deflection direction of the AOD described in FIG. 11 and the distance δ between the two deflection directions of the first and second AODs described in FIG. 9(b) occur. The overlap of these two offsets can result in the deflection position being positioned at the pixel center. For example, in the example of FIG. 12, θ1 = -arctan(Dy / (3Dx)), θ2 = arctan(Dy / (3Dx)), δ = 5Dy / 3, and point G where Δx = 0 and Δy = 0 is positioned at the pixel center. In this case, for example, in the deflection direction of the first AOD, point F3A, the second from the left, is offset by Dy / 3 from the pixel center toward the top of FIG. 12, while in the deflection direction of the second AOD, point F4B, the second from the left, is positioned at the pixel center. This is because δ=5Dy / 3 causes the deflection direction of the second AOD to be shifted by 2Dy / 3 in the vertical direction in Fig. 12 relative to the deflection direction of the first AOD, so that the position of the second AOD relative to the pixel center is shifted by 2Dy / 3. Note that in the deflection direction of the first AOD, the first, fourth, seventh, etc. points from the left are placed at the pixel center, whereas in the deflection direction of the second AOD, the second, fifth, eighth, etc. points from the left are placed at the pixel center.

[0092] So far, we have explained the case where the laser irradiation pitch calculated from the galvanometer main scanning speed and repetition frequency is equal to the pixel size, that is, the case where the laser can be irradiated once while the galvanometer scanning trajectory passes over one pixel (and where one pixel can be marked with one pulse), but we will now explain other cases.

[0093] Fig. 13 is a diagram illustrating multiple irradiations of laser light during acceleration / deceleration. Note that Fig. 13 shows, as an example, a case in which only the first AOD is used and the angle θ between the deflection direction of the first AOD and the +x direction is 0.

[0094] The galvanometer scanner needs to be accelerated until the main scanning speed is sufficiently high. As shown in FIG. 13 here, let A be the length required for accelerating or decelerating the main scanning speed, L be the main scanning length, and Y be the marking image length in the main scanning direction. At this time, when L - 2A < Y, that is, when the length of the region where a sufficient main scanning speed can be obtained is shorter than the full length of the image, the galvanometer scanner cannot achieve a sufficient speed at the ends of the image region in the main scanning direction. Therefore, in this region, the laser light may be irradiated two or more times while the galvanometer scanning trajectory passes through one pixel. For example, while passing through the pixel (non-irradiated region) at (x0, y0) = (1, 1) in FIG. 13, two pixels at (5, 1) and (6, 1) are marked. Similarly, at the pixel (irradiated region) at (x0, y0) = (1, 18), two pixels at (1, 18) and (2, 18) are marked. Since the irradiation timings of each two pixels are different, the irradiation positions are shifted in the main scanning direction.

[0095] In the above explanation, for simplicity, the case of irradiating twice has been described, but the number of irradiations may be more than two. Also, the number of (x0, y0) where multiple irradiations are possible changes depending on the relationship with the acceleration / deceleration length and the pixel size. In FIG. 13, L > Y is assumed, but L ≤ Y may also be acceptable. By providing a plurality of AODs, the drawable range in the main scanning direction can be made larger than the main scanning length, so it becomes possible to draw the entire image region after setting L ≤ Y. In FIG. 13, an example of drawing the pixels at the ends in the main scanning direction in the acceleration / deceleration region A is shown, but it is also possible to draw pixels other than the ends by setting θ to an angle other than 0 or by using the second AOD in this region.

[0096] In addition, for example, a method is also possible where the laser irradiation pitch calculated from the galvanometer main scanning speed and the repetition frequency is set to half of the pixel size, and two pixels are marked while passing through one pixel as shown in FIG. 14. In FIG. 14, θ = -arctan(Dy / 2Dx). The solid arrows in FIG. 14 indicate the scanning trajectory of the laser light by the galvanometer scanner, the dotted arrows indicate the deflection positions by the AOD, and the cross marks indicate the laser irradiation positions.

[0097] Here, the example shows a case where the laser irradiation pitch is half the pixel size, but the laser irradiation pitch may be smaller than half the pixel size. In that case, in principle, it is possible to mark two or more pixels while the laser passes through one pixel. When the number of pulses that can be irradiated while passing through one pixel is m, it is preferable to set θ = arctan(n × Dy / (m × Dx)), as this increases the number of pulses that can be deflected toward the pixel center. For simplicity, Figure 14 shows the use of only the first AOD, but it is also possible to use other AODs.

[0098] Furthermore, the configurations of Figures 13 and 14 may be combined. For example, in a laser irradiation device capable of irradiating laser light multiple times (twice in Figure 14) while passing through one pixel as shown in Figure 14, in a section where the main scanning speed of the galvano scanner is accelerating or decelerating as shown in Figure 13, it is also possible to configure the device to irradiate laser light more times (three or more times) than the number of times (twice) that laser light is irradiated in a section where the main scanning speed is constant.

[0099] FIG. 15 is a block diagram showing the control unit of the laser irradiation device.

[0100] As shown in FIG. 15, the control unit 150 of the laser irradiation device includes an image pattern data input unit 151, a storage unit 152, a processing data generation unit 153, a laser irradiation control unit 154, a first laser scanning control unit 157, a second laser scanning control unit 158, etc.

[0101] A processing data generation unit 153 generates processing data based on image pattern data input to an image pattern data input unit 151. This processing data is input to a laser irradiation control unit 154, a first laser scanning control unit 157, and a second laser scanning control unit 158. A light intensity control unit 155 and a pulse control unit 156 in the laser irradiation control unit 154 determine the intensity of the laser light to be irradiated, the pulse interval, etc. based on the processing data, and cause the laser oscillator 10 to irradiate the laser light. The first laser scanning control unit 157 controls the ON / OFF of the first AOD 21 and the second AOD 22 based on the processing data. The second laser scanning control unit 158 controls the galvano scanner 30 based on the processing data.

[0102] Figure 16(b) shows a timing chart of the control of the first AOD for the marking example in Figure 16(a). For convenience, Figure 16 shows an example of control using only the first AOD. The correspondence between the aod_data value and the displacement Δx due to deflection is shown in Table 5 below.

[0103] [Table 5]

[0104] As shown in Figures 16(a) and 16(b), the aod_data signal is the frequency value (here, 4 bits) of the RF signal to be applied to the AOD element, and the frequency value is reflected in the AOD element by the latch signal. Next, the laser light is turned on at the timing of the laser_pulse signal. The laser light is deflected in the x direction by the AOD element at an angle corresponding to the frequency value set at the time of turning on the laser light.

[0105] It is desirable to be able to adjust the time between the laser_pulse signal and the latch signal in order to adjust the timing of the laser lighting and the timing of the deflection by the AOD. It is desirable to input the latch signal prior to the timing of the laser lighting, taking into account the latency of the AOD response.

[0106] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0107] In the above description, the case where the laser light is raster scanned by the galvanometer scanner (downstream deflector) has been described, but the present invention is not necessarily limited to this. In other words, the present invention may also be configured such that the laser light deflected by the downstream deflector to a position other than the raster scanning position is deflected to a plurality of different positions by a plurality of upstream deflectors.

[0108] In the above explanation, we have described a case where the raster scanning trajectory of the laser light by the galvanometer scanner (downstream deflector) passes through the center position of the scanned area. In other words, if the line connecting the centers of each pixel in the same column (each pixel at the same position in the x direction) is defined as the center axis of that column, we have described a case where the main scanning axis of the raster scanning coincides with the center axis of each column. However, the present invention is not necessarily limited to this, and the main scanning axis of the raster scanning may be shifted in the x direction from the center axis of the column.

[0109] Although the above examples show the use of the first-order diffracted light of the AOD, the same effect can be obtained by using -1st-order light or higher-order light of the second or higher order. Furthermore, it is also possible to use a combination of light of multiple orders, such as using both zeroth-order and first-order light.

[0110] The above explanation shows the case where the absolute values of the angles θ1 and θ2 are the same, and in particular in FIG. 6(c), θ1 and θ2 are set so as to be symmetrical with respect to the sub-scanning direction passing through the zero-order light E, that is, so as to pass through the same x-coordinate, but the present invention is not limited to this.

[0111] 17, the absolute value of the angle θ1 is larger than the absolute value of the angle θ2, and the x-coordinates of the deflection directions F1 and F2 are different. However, only the absolute values may differ, or the x-coordinates may be partially the same.

[0112] Although the above description has been given of a laser irradiation device having only two AODs, it may have three or more AODs. For example, the following description will be given of a laser irradiation device having a third AOD as an upstream deflector in addition to the first and second AODs.

[0113] As shown in Figure 18, the third AOD has a deflection direction different from the first and second AODs, and the angle θ3 between the deflection direction and the +x direction is 0. This allows the laser irradiation device to have a deflection region F3 in addition to deflection regions F1 and F2. This increases the number of deflection positions available, allowing the laser irradiation device to more efficiently irradiate the irradiation target with laser light. However, θ1, θ2, and θ3 can be set to any value.

[0114] In the above embodiments, only one AOD is turned on at a time, i.e., multiple AODs are not turned on at the same time. However, the present invention is not limited to this. For example, in the embodiment shown in FIG. 19, the first and second AODs are turned on simultaneously. As a result, the laser irradiation device shown in FIG. 19 can deflect laser light to the deflection region indicated by arrow F3 and to a position within the rectangular deflection region J obtained by combining arrows F1 and F2. This increases the number of possible deflection positions, allowing the laser irradiation device to more efficiently irradiate the irradiation target with laser light. However, when deflecting laser light within the rectangular region J, the energy efficiency of the laser light decreases compared to when deflecting laser light to the region indicated by arrow F3. On the other hand, when deflecting laser light to the rectangular deflection region J, for example, the irradiation density of the laser pulse may be increased. In particular, as shown in FIG. 19, setting θ1 and θ2 so that arrows F1 and F2 are orthogonal increases the diffraction efficiency of the laser light when deflected to the rectangular region J, which is preferable.

[0115] In the above explanation, for convenience, each deflection position is shown as an arrow from a position on the raster scan. However, the actual scanning trajectory of the laser light differs from this, and the deflection position change time by each AOD is set to be the shortest. Taking the first AOD as an example, consider the case where, as shown in FIG. 20 , the laser light is deflected to point HA at a distance a from the irradiation position E of the zero-order light at the jth time, and to point HB at a distance b from point E at the j+1th time. These distances a and b are defined as the deflection distance by the first AOD (the distance from point E when deflection by the first AOD is not performed). In this case, the deflection position of the first AOD is set to be between points HA and HB in the jth to j+1th section. In other words, the deflection position by the first AOD is set so that the deflection distance is between the deflection distance a from point E and the change distance b within the deflection direction F1 by the first AOD. Note that deflection by another AOD may be interposed between the jth and j+1th AODs. In this case, in the section between the jth and j+1th beams, in the section deflected by the first AOD, the deflection position by the first AOD is set to be a position between points HA and HB.

[0116] The laser irradiation device according to the embodiment of the present invention can be applied to a three-dimensional object molding device. Fig. 21 shows a powder bed fusion bonding device 400, which is an example of the three-dimensional object molding device.

[0117] The powder bed fusion and bonding system 400 irradiates a powder bed, which is made up of multiple powder layers, with a laser beam to fuse and bond specific laser beam irradiated areas of the powder bed to form a three-dimensional object. Specifically, powder material is first spread evenly to form a layer. Next, a laser beam is irradiated at desired positions on the layer to selectively sinter or melt particles contained in the powder material, thereby bonding the particles.

[0118] This separates the three-dimensional object into multiple layers in the thickness direction, forming one layer. A layer of powder material is then spread on top of the layer, and the next layer is formed by irradiating it with laser light.

[0119] By repeating this procedure and stacking the layers of the object, a three-dimensional object of the desired shape is produced. The powder material may be a resin material or a metal material, and two or more types may be mixed as appropriate, or additives may be further added.

[0120] The powder bed fusion apparatus 400 includes a build stage 310, a layer formation unit 320, a preheating unit 330, a temperature measuring device 335, and a laser irradiation device 100. The build stage 310 is a stage on which a three-dimensional object is built. The stage support unit 350 supports the build stage 310 so that its vertical position can be changed.

[0121] The modeling stage 310 is configured to be precisely movable in the vertical direction by a stage support unit 350. The stage support unit 350 can have various configurations, but for example, it can be configured with a holding member that holds the modeling stage 310, a guide member that guides the holding member in the vertical direction, and a ball screw or the like that engages with a screw hole provided in the guide member.

[0122] The layer forming unit 320 forms a layer. The layer forming unit 320 includes a powder supplying unit 321 that supplies powder and a recoater 322a that flattens the powder on the modeling stage 310.

[0123] The layer formation unit 320 includes, for example, an opening whose edge is substantially flush with the edge of the opening through which the modeling stage 310 moves up and down, and a powder material storage unit extending vertically downward from the opening. The powder supply unit 321 includes a supply piston that is provided at the bottom of the powder material storage unit and moves up and down within the opening. The powder supply unit 321 may also include a powder material storage unit provided vertically above the modeling stage 310 and a nozzle, so that the powder material is dispensed onto the same horizontal plane as the modeling stage.

[0124] The preheating unit 330 preheats the layer formed in the layer forming unit 320. The preheating unit 330 may be any unit that can heat at least the area of the surface of the layer where the model layer is to be formed and maintain that temperature.

[0125] For example, the preheating unit 330 may be configured to include a first heater 331a that can heat the surface of the layer formed on the modeling stage 310, or may further include a second heater 332 that heats the powder material before it is supplied to the modeling stage. The preheating unit 330 may be configured to selectively heat an area where a model layer is to be formed, or may be configured to heat the entire interior of the device and adjust the surface temperature of the formed layer to a predetermined temperature.

[0126] The first heater 331 may be heater 331a that heats the layer from the top, heater 331b that heats the layer from the side, heater 331c that heats the layer from the bottom, or any combination of these. However, the surface temperature of the layer tends to increase near the first heaters 331a, 331b, and 331c, and the surface temperature of the layer tends to increase less the further away from the first heaters 331a, 331b, and 331c.

[0127] Therefore, from the viewpoint of preventing temperature unevenness on the surface of the layer and preventing deformation of the model layer due to temperature unevenness on the surface of the layer, it is preferable that the first heater 331 includes a plurality of heaters that are spaced apart from one another. In this case, it is preferable that the plurality of first heaters 331a, the plurality of first heaters 331b, and the plurality of first heaters 331c are spaced apart from one another at equal intervals.

[0128] The temperature measuring device 335 measures the temperature of the layer. Any device capable of measuring the surface temperature of the area where the model layer is to be formed in a non-contact manner may be used, such as an infrared sensor or an optical pyrometer.

[0129] The laser irradiation device 100 irradiates a powder bed with laser light. A model layer is formed by the irradiation of the laser light. The laser irradiation device 100 includes a laser oscillator 10, a first AOD 21, a second AOD 22, half-wave plates 23 and 24, and a galvanometer scanner 30.

[0130] The laser irradiation device 100 may include a laser window 343 that transmits laser light. The laser window 343 may be made of any material that transmits laser light.

[0131] In the powder bed fusion apparatus 400, if there is any unevenness in the pre-heating temperature applied in the pre-heating section 330, there will also be an unevenness in the rate of change in the volume (specific volume) of the powder irradiated with laser light, resulting in a decrease in the accuracy of the three-dimensional object. Therefore, the temperature is measured by the temperature measuring device 335, and the energy of the laser light irradiated by the laser irradiation device 100 is adjusted according to the temperature result.

[0132] Specifically, when the preheating temperature is low, the energy given to the particles in the irradiated portion from the laser light is increased, and when the preheating temperature is high, the energy given to the particles in the irradiated portion from the laser light is reduced.

[0133] When the scanning means scans two or more irradiation regions and non-irradiation regions sandwiched between the irradiation regions, the laser irradiation device 100 controls the irradiation means and the scanning means so that the scanning is performed at a constant speed within the irradiation regions and the scanning speed is changed within the non-irradiation regions. In other words, in order to increase or decrease the energy due to laser irradiation, the laser irradiation device 100 controls the energy due to laser irradiation that a particle receives per unit time by changing the scanning speed of the laser scan.

[0134] In the laser irradiation device 100 shown in Fig. 21, the scanning speed can be precisely controlled for each irradiation region, and therefore the energy of the laser beam applied to the powder particles for sintering or melting can be precisely controlled. As a result, the rate of change in the volume (specific volume) of the resin due to unevenness in the pre-heating can be made uniform, preventing a decrease in the accuracy of the three-dimensional object. Furthermore, in the raster scanning of the laser beam, the laser output can be effectively utilized and productivity can be improved.

[0135] By applying the configuration of the above-described embodiment to the laser irradiation apparatus 100 provided in the powder bed fusion bonding apparatus 400, the laser can be efficiently irradiated onto the irradiation target area of the laser irradiation target.

[0136] The aspects of the present invention are as follows, for example. <1> a plurality of upstream deflectors for deflecting the laser beam; a downstream deflector that deflects laser light downstream of the upstream deflector, the upstream deflector includes at least a first upstream deflector and a second upstream deflector; the laser light deflected by the downstream deflector is deflected by the first upstream deflector or the second upstream deflector to be irradiated onto an unirradiated region; This laser irradiation device is characterized by including at least one of the cases where laser light is deflected only by the first upstream deflector and the second upstream deflector, and the case where laser light is deflected only by the second upstream deflector. <2> There is only one upstream deflector that deflects the laser light at the same time. <1> The laser irradiation device described above. <3> The laser light, which moves to a non-irradiation area by the downstream deflector when deflected to a reference deflection position by the upstream deflector, is deflected by the upstream deflector to a position different from the reference deflection position, thereby irradiating an unirradiated area spaced apart from the non-irradiation area. <1> or <2> The laser irradiation device described above. <4> Of the first upstream deflector and the second upstream deflector, the present invention includes both a case where the laser light is deflected only by the first upstream deflector and a case where the laser light is deflected only by the second upstream deflector. <1> from <3> The laser irradiation device according to any one of the preceding claims. <5> The plurality of upstream deflectors perform a plurality of deflections in different deflection directions. <1> from <4> The laser irradiation device according to any one of the preceding claims. <6> The upstream deflector is an acousto-optical element or an electro-optical element. <1> from <5> The laser irradiation device according to any one of the preceding claims. <7> The time from when a laser beam is irradiated onto a certain area until the laser beam is deflected to a deflection position corresponding to the next area is equal to or less than the lighting period of the laser beam. <1> from <6> The laser irradiation device according to any one of the preceding claims. <8> The downstream deflector raster-scans the laser beam. <1> from <7> The laser irradiation device according to any one of the preceding claims. <9> The sub-scanning direction of the raster scan is defined as direction x, the main scanning direction is defined as direction y, and in a plurality of scanning target areas of the irradiation object arranged in a grid pattern, the direction x is defined as the column of the scanning target area, the direction y is defined as the row of the scanning target area, and the line connecting the center positions of the direction x of each scanning target area in the same column is defined as the central axis of the column. a main scanning axis of a raster scan by the downstream deflector coincides with the central axis of any one of the rows; The laser beam is deflected by the upstream deflector to a position on the raster scan at the time of the deflection, the position being different from the value of the direction x. <8> The laser irradiation device described above. <10> If the main scanning direction of the raster scan is direction y, the sub-scanning direction of the raster scan is direction x, and the upstream side of the raster scan is the negative direction of direction x and the downstream side is the positive direction of direction x, then: The x coordinate of the main scanning row to be raster scanned is determined so that the laser light can be irradiated onto the area with the smallest value in the direction x among the irradiation target area and non-irradiated area of the irradiation target object, and the laser light is irradiated onto the area with the smallest value in the direction x when the row is raster scanned. <8> or <9> The laser irradiation device according to any one of the preceding claims. <11> The x-coordinate of the unirradiated area having the smallest value in the x direction among the irradiation target area and unirradiated area of the irradiation target is set as the column for performing the raster scan. <10> The laser irradiation device described above. <12> On an xy plane where the main scanning direction of the raster scan is direction y and the sub-scanning direction of the raster scan is direction x, the angle formed by the deflection direction of the upstream deflector with respect to the sub-scanning direction of the downstream deflector is angle θ, the distance between the scanning target areas in the direction x is Dx, the distance between the scanning target areas in the direction y is Dy, and n and m are integers, the following formula (1) is satisfied: <8> from <11> The laser irradiation device according to any one of the preceding claims. θ=±arctan((n×Dy) / (m×Dx)) ···(1) <13> On an xy plane where the main scanning direction of the raster scan is direction y and the sub-scanning direction of the raster scan is direction x, the angle formed by the deflection direction of the upstream deflector with respect to the sub-scanning direction of the downstream deflector is angle θ, and the upstream deflector has a plurality of deflectors whose absolute values of angle θ are equal but whose directions are different. <8> from <12> The laser irradiation device according to any one of the preceding claims. <14> On an xy plane, where the main scanning direction of the raster scanning is direction y and the sub-scanning direction of the raster scanning is direction x, the angle formed by the deflection direction of the upstream-side deflector with respect to the sub-scanning direction of the downstream-side deflector is angle θ, The angle θ is determined so that the deflection direction of the upstream deflector is different from the direction of the largest line segment formed by the irradiation target area of the irradiation target. <8> from <13> The laser irradiation device according to any one of the preceding claims. <15> Let the j-th deflection distance by an upstream deflector be distance a, and the j+1-th deflection distance be distance b. The upstream deflector deflects the laser light by a distance between a distance a and a distance b with respect to a position on the raster scan in a section between the j-th deflection position and the j+1-th deflection position in which the upstream deflector deflects the laser light. <8> from <14> The laser irradiation device according to any one of the preceding claims. <16> The downstream deflector performs raster scanning, allowing the laser beam to be irradiated multiple times while passing through one scanning target area. <8> from <15> The laser irradiation device according to any one of the preceding claims. <17> The number of times that the laser light can be irradiated while passing through one scanning target area by the raster scanning is greater in a section where the raster scanning by the downstream deflector is accelerating or decelerating in the main scanning direction than in a section where the raster scanning by the downstream deflector is at a constant speed. <8> from <16> The laser irradiation device according to any one of the preceding claims. <18> The object to be irradiated is resin, and the resin is irradiated with laser light to form a concave shape on its surface. <1> from <17> The laser irradiation device according to any one of the preceding claims. <19> For an irradiated area of a powder bed where powder layers are formed sequentially in multiple layers, <1> from <17> A modeling apparatus that models a three-dimensional object by repeatedly irradiating laser light using any one of the laser irradiation apparatuses. <20> A laser irradiation method in which a laser beam deflected by an upstream deflector is deflected by a downstream deflector and then irradiated onto an irradiation object, comprising: At least a first upstream deflector and a second upstream deflector are used as the upstream deflector; the laser light deflected by the downstream deflector is deflected by the first upstream deflector or the second upstream deflector to be irradiated onto an unirradiated region; This is a laser irradiation method characterized by including at least one of a case where the laser light is deflected only by the first upstream deflector and a case where the laser light is deflected only by the second upstream deflector, out of the first upstream deflector and the second upstream deflector. [Explanation of symbols]

[0137] 10 Laser oscillator (light source) 21 1st AOD (Upstream deflector or 1st upstream deflector) 22 Second AOD (Upstream deflector or second upstream deflector) 30 Galvanometer scanner (downstream deflector) 50 Marking object (irradiation object) 100 Laser irradiation device B Raster scanning trajectory by galvanometer scanner C AOD deflection direction G. Reference deflection position by the first AOD (reference deflection position by the upstream deflector) x Sub-scan direction of raster scan y Main scanning direction of raster scan θ is the angle between the deflection direction of the AOD and the sub-scanning direction of the raster scan [Prior art documents] [Patent documents]

[0138] [Patent Document 1] Special Publication No. 2012-528011

Claims

1. a plurality of upstream deflectors for deflecting the laser beam; a downstream deflector that deflects laser light downstream of the upstream deflector, the upstream deflector includes at least a first upstream deflector and a second upstream deflector; the laser light deflected by the downstream deflector is deflected by the first upstream deflector or the second upstream deflector to be irradiated onto an unirradiated region; A laser irradiation device characterized by including at least one of a case where laser light is deflected only by the first upstream deflector and a case where laser light is deflected only by the second upstream deflector, out of the first upstream deflector and the second upstream deflector.

2. 2. The laser irradiation device according to claim 1, wherein the number of said upstream deflectors that deflect the laser beams at the same timing is one.

3. 2. The laser irradiation device according to claim 1, wherein the laser light, which moves to a non-irradiation area by the downstream deflector when deflected to a reference deflection position by the upstream deflector, is deflected by the upstream deflector to a position different from the reference deflection position, thereby irradiating an unirradiated area spaced from the non-irradiation area.

4. 2. The laser irradiation device according to claim 1, wherein the laser irradiation device includes both a case where the laser light is deflected only by the first upstream deflector and a case where the laser light is deflected only by the second upstream deflector.

5. 2. The laser irradiation device according to claim 1, wherein a plurality of deflections in different directions are performed by a plurality of said upstream deflectors.

6. 2. The laser irradiation device according to claim 1, wherein the upstream deflector is an acousto-optical element or an electro-optical element.

7. 2. The laser irradiation device according to claim 1, wherein the time from when a region is irradiated with laser light until the laser light is deflected to a deflection position corresponding to the next region is equal to or less than the lighting period of the laser light.

8. 2. The laser irradiation device according to claim 1, wherein the downstream deflector raster-scans the laser beam.

9. The sub-scanning direction of the raster scan is defined as direction x, the main scanning direction is defined as direction y, and in a plurality of scanning target areas of an irradiation object arranged in a grid pattern, the direction x is defined as a column of the scanning target area, the direction y is defined as a row of the scanning target area, and a line connecting the center positions of the direction x of each scanning target area in the same column is defined as the central axis of the column. a main scanning axis of a raster scan by the downstream deflector coincides with the central axis of any one of the rows; 9. The laser irradiation device according to claim 8, wherein the laser beam is deflected by the upstream deflector to a position on the raster scan line having a different value of the direction x from the position at the time of the deflection.

10. If the main scanning direction of the raster scan is direction y, the sub-scanning direction of the raster scan is direction x, and the upstream side of the raster scan is the negative direction of direction x and the downstream side is the positive direction of direction x, then:

9. The laser irradiation device according to claim 8, wherein the x coordinate of the main scanning row to be raster scanned is determined so that the laser light can be irradiated onto an area having the smallest value in the direction x among the irradiation target area and non-irradiated areas of the irradiation object, and when raster scanning the row, the laser light is irradiated onto the area having the smallest value in the direction x.

11. 11. The laser irradiation device according to claim 10, wherein the x coordinate of the non-irradiated area having the smallest value in the x direction among the non-irradiated areas of the irradiation target area is set as the row for performing the raster scan.

12. 9. The laser irradiation device according to claim 8, wherein on an xy plane, where the main scanning direction of the raster scanning is direction y and the sub-scanning direction of the raster scanning is direction x, the angle formed by the deflection direction of the upstream deflector with respect to the sub-scanning direction of the downstream deflector is angle θ, the distance between the scanning target areas in direction x is Dx, the distance between the scanning target areas in direction y is Dy, and n and m are integers, satisfies the following formula (1): θ=±arctan((n×Dy) / (m×Dx))...(1)

13. 9. The laser irradiation device according to claim 8, wherein, on an xy plane in which the main scanning direction of the raster scanning is direction y and the sub-scanning direction of the raster scanning is direction x, the angle formed by the deflection direction of the upstream deflector with respect to the sub-scanning direction of the downstream deflector is angle θ, the laser irradiation device has a plurality of upstream deflectors having the same absolute value of angle θ but different directions.

14. On an xy plane, where the main scanning direction of the raster scan is direction y and the sub-scanning direction of the raster scan is direction x, the angle formed by the deflection direction of the upstream-side deflector with respect to the sub-scanning direction of the downstream-side deflector is angle θ, 9. The laser irradiation device according to claim 8, wherein the angle .theta. is determined so that the deflection direction of the upstream deflector is different from the direction of the largest line segment formed by the irradiation target area of the irradiation target.

15. If the j-th deflection distance by a certain upstream deflector is distance a, and the j+1-th deflection distance is distance b, then 9. The laser irradiation device according to claim 8, wherein the upstream deflector deflects the laser light by a distance between a distance a and a distance b relative to a position on a raster scan in a section between the jth deflection position and the j+1th deflection position in which the upstream deflector deflects the laser light.

16. 9. The laser irradiation device according to claim 8, wherein the laser beam can be irradiated a plurality of times while passing through one scanning target area by raster scanning by the downstream deflector.

17. 9. The laser irradiation device according to claim 8, wherein the number of times that the laser light can be irradiated while passing through one scanning target area by the raster scanning is greater in a section where the raster scanning by the downstream deflector is accelerating or decelerating in the main scanning direction than in a section where the raster scanning by the downstream deflector is at a constant speed.

18. 18. The laser irradiation device according to claim 1, wherein the object to be irradiated is a resin, and the laser irradiation device irradiates the resin with laser light to process the resin so as to form a concave shape on its surface.

19. 18. A molding apparatus for molding a three-dimensional object by repeatedly irradiating an irradiation area of a powder bed in which powder layers are sequentially formed in a plurality of layers with laser light by the laser irradiation apparatus according to claim 1.

20. A laser irradiation method in which a laser beam deflected by an upstream deflector is deflected by a downstream deflector and then irradiated onto an irradiation object, comprising: At least a first upstream deflector and a second upstream deflector are used as the upstream deflectors; the laser light deflected by the downstream deflector is deflected by the first upstream deflector or the second upstream deflector to be irradiated onto an unirradiated region; A laser irradiation method comprising at least one of a case where the laser beam is deflected only by the first upstream deflector and a case where the laser beam is deflected only by the second upstream deflector, out of the first upstream deflector and the second upstream deflector.

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