Light irradiation device

Abstract

To provide a technique capable of improving drawing efficiency when rotating laser light using a rotating optical element to draw a pattern.SOLUTION: A light irradiation device 1 includes: a light source; a beam shaping unit 3 that expands laser light from the light source in one direction; a beam modulation unit 4 that modulates an intensity distribution of the laser light from the beam shaping unit 3 in one direction; a beam rotation unit 5 having a plurality of rotating optical elements 531, 551 that rotate the laser light from the beam modulation unit 4 about an optical axis; and a scanning unit 6 that scans a surface of an object with the laser light from the beam rotation unit 5. The beam rotation unit 5 includes a switching part 51 that switches a path of the laser light from the beam modulation unit 4 between a first path and a second path, a rotating optical element 531 that rotates the laser light about the optical axis on the first path, and a rotating optical element 551 that rotates the laser light about the optical axis on the second path.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The subject matter disclosed herein relates to a light irradiation device. [Background technology]

[0002] Patent Document 1 discloses a laser processing device that forms a pattern on the surface of an object to be printed by scanning the surface of the object with a linear beam spot whose intensity distribution in the major axis direction is modulated. Patent Document 2 also discloses a laser irradiation device equipped with a laser beam rotation means that rotates the irradiated laser beam around the optical axis. Rotating the laser beam makes it possible to scan in any direction, thereby efficiently drawing patterns. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-000231 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-004877 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when scanning by rotating a laser beam as in Patent Document 2, it is necessary to continuously change the rotation angle of the laser beam. In this case, if the operation of the rotating optical element is slow, it takes time to change the rotation angle of the laser beam, which may result in a decrease in drawing efficiency.

[0005] An object of the present invention is to provide a technique capable of improving drawing efficiency when a pattern is drawn by rotating a laser beam using a rotating optical element. [Means for solving the problem]

[0006] In order to solve the above problem, a first aspect is a light irradiation device comprising: a light source that emits laser light; a beam shaping unit that expands the laser light from the light source in one direction; a beam modulation unit that modulates the intensity distribution in the one direction of the laser light from the beam shaping unit; a beam rotation unit having a plurality of rotating optical elements that rotate the laser light from the beam modulation unit about an optical axis; and a scanning unit that scans a surface of an object with the laser light from the beam rotation unit, wherein the beam rotation unit includes a switching unit that switches the path of the laser light from the beam modulation unit to either a first path or a second path; a first rotating optical element that rotates the laser light about the optical axis on the first path; and a second rotating optical element that rotates the laser light about the optical axis on the second path.

[0007] A second aspect is the light irradiation device of the first aspect, wherein the first rotating optical element further includes a first mirror that reflects the incident laser light, a second mirror that reflects the laser light reflected by the first mirror, a third mirror that reflects the laser light reflected by the second mirror, and a rotation drive unit that rotates the first mirror, the second mirror, and the third mirror together.

[0008] A third aspect is a light irradiation device that irradiates a line-shaped spot beam onto the surface of an object, and includes a light source that emits laser light, a beam shaping unit that expands the laser light from the light source in one direction, a beam modulation unit that modulates the intensity distribution in the one direction of the laser light from the beam shaping unit, a beam rotation unit having a plurality of rotating optical elements that rotate the laser light from the beam modulation unit about an optical axis, and a scanning unit that scans the surface of the object with the laser light from the beam rotation unit, wherein the plurality of rotating optical elements are arranged in series on the path of the laser light. [Effects of the Invention]

[0009] According to the light irradiation devices of the first and second aspects, the laser beam can be rotated by switching between the first and second paths. Therefore, while drawing is being performed with the laser beam that has passed through one path, the rotating optical element of the other path can be rotated. This allows the rotation angle of the laser beam to be changed simply by switching the path, thereby improving drawing efficiency.

[0010] According to the light irradiation device of the second aspect, the optical path is configured only with total reflection mirrors, so that even if the incident laser beam is not collimated, it is possible to rotate the laser beam satisfactorily.

[0011] According to the light irradiation device of the third aspect, by arranging a plurality of rotating optical elements in series, the final rotation angle of the laser beam becomes the sum of the rotation angles of the individual rotating optical elements. This reduces the rotation angle of each rotating optical element. Therefore, the rotation angle of the laser beam can be quickly changed, thereby improving the drawing efficiency. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing a configuration of a light irradiation device according to an embodiment. [Figure 2] 2 is a diagram showing the structure of the spatial light modulator shown in FIG. 1. FIG. [Figure 3] FIG. 2 is a diagram showing the configuration of a beam rotation unit shown in FIG. [Figure 4] 2 is a diagram showing the configuration of a rotating optical element included in the beam rotating unit shown in FIG. 1. FIG. [Figure 5] 2 is a block diagram showing a hardware configuration of a control unit shown in FIG. 1. FIG. [Figure 6] FIG. 1 is a conceptual diagram illustrating scanning of the surface of an object with a modulated beam. [Figure 7] 10 is a timing chart showing the timing of control of the rotation angle by the control unit. [Figure 8] FIG. 10 is a diagram showing the configuration of a rotating optical element according to a first modified example. [Figure 9]FIG. 10 is a diagram showing the configuration of a rotating optical element according to a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the components described in the embodiment are merely examples and are not intended to limit the scope of the present invention. In the drawings, the dimensions and numbers of each part may be exaggerated or simplified as necessary to facilitate understanding.

[0014] <1. Embodiment> FIG. 1 is a diagram showing the configuration of a light irradiation device 1 according to an embodiment. The light irradiation device 1 is a device that irradiates a laser beam onto the surface of an object 9 held by a holder 11. The light irradiation device 1 may be configured as, for example, a laser marker device. In this case, by irradiating the object 9 with a laser beam, an oxide film is formed on the surface of the object 9, or a microstructure is formed by peeling, etc., thereby marking characters or figures. In the case of a laser marker device, the surface of the object 9 is formed of a metal such as stainless steel, copper, or titanium. In the following description, the object 9 is assumed to be plate-shaped. However, the shape of the object 9 is not limited to being plate-shaped.

[0015] The light irradiation device 1 includes a laser light source 2, a beam shaping unit 3, a beam modulation unit 4, a beam rotation unit 5, a scanning unit 6, and a control unit 7. The laser light source 2 emits laser light L31 to the beam shaping unit 3. The laser light source 2 is, for example, a fiber laser light source. The wavelength of the laser light L31 is, for example, 1064 nm. The wavelength of the laser light L31 is selected appropriately depending on the type of the target object 9.

[0016] The beam shaping unit 3 shapes the laser light from the laser light source 2 into a linear laser light L32 that is long in one direction by expanding it in one direction, and then guides it to the beam modulation unit 4. Hereinafter, the direction in which the laser light L32 expands will be referred to as the long axis direction. The cross-sectional shape of the laser light L32 emitted from the beam shaping unit 3 is approximately rectangular, being long in the long axis direction and short in the short axis direction perpendicular to the long axis direction. Note that the cross section of light refers to the surface of the cut when the light is cut along a plane perpendicular to the optical axis of the light. The laser light L32 is preferably a parallel beam. Note that it is not essential that the laser light L32 be a parallel beam, and the laser light L32 may be a diverging beam.

[0017] The beam modulation unit 4 modulates the laser light L32 from the beam shaping unit 3 into a modulated beam L33 and guides the modulated beam L33 to the beam rotation unit 5. The beam modulation unit 4 has a spatial light modulator 41. The spatial light modulator 41 changes the intensity distribution of the laser light L32 in the major axis direction. The spatial light modulator 41 has, for example, a PLV (Planar Light Valve). The following describes a case where the spatial light modulator 41 has an LPLV (Linear Planar Light Valve), which is a type of PLV. Compared to, for example, a GLV (Grating Light Valve) (registered trademark), an LPLV has the same power resistance per unit area of ​​the element but a larger effective area. In other words, the larger effective area allows it to handle higher power than a GLV.

[0018] FIG. 2 is a diagram showing the structure of the spatial light modulator 41 shown in FIG. 1. The spatial light modulator 41 has a plurality of substantially rectangular pixels 411. The plurality of pixels 411 are arranged adjacent to each other on a substrate (not shown). The plurality of pixels 411 are arranged in a matrix of a plurality of rows and a plurality of columns. That is, the pixels 411 are arranged two-dimensionally. In the spatial light modulator 41, the surfaces of the plurality of pixels 411 serve as modulation surfaces. In the example shown in FIG. 2, M pixels 411 are arranged in the vertical direction and N pixels 411 are arranged in the horizontal direction. The horizontal direction in FIG. 2 corresponds to the long-axis direction of the laser light L32, and the vertical direction in FIG. 2 corresponds to the short-axis direction of the laser light L32. In the following description, the M pixels 411 arranged in a vertical row may be referred to as a "pixel row."

[0019] Each pixel 411 is a modulation element including a fixed member 412 and a movable member 413. The fixed member 412 is a planar, approximately rectangular member fixed to the substrate and has a substantially circular opening in the center. The movable member 413 is approximately circular and is located in the opening of the fixed member 412. The upper surface of the fixed member 412 (i.e., the surface on the near side in the direction perpendicular to the paper surface in FIG. 2) has a fixed reflecting surface. The upper surface of the movable member 413 has a movable reflecting surface. The movable member 413 is movable in the direction perpendicular to the paper surface in FIG. 2.

[0020] By changing the relative position of the movable member 413 with respect to the fixed member 412, the reflected light from the pixel 411 is switched between zeroth-order light (i.e., specularly reflected light) and non-zeroth-order diffracted light. In other words, by moving the movable member 413 relative to the fixed member 412, light modulation using a diffraction grating is performed. The zeroth-order light emitted from the spatial light modulator 41 passes through several lenses that make up the projection optical system and is guided in this order to the beam rotation unit 5 and the scanning unit 6. Note that the non-zeroth-order diffracted light (mainly first-order diffracted light) emitted from the spatial light modulator 41 is guided, for example, in a direction different from the beam rotation unit 5 and is appropriately shielded.

[0021] The cross-sectionally linear laser beam L32 emitted from the beam shaping unit 3 is appropriately expanded in the minor axis direction in accordance with the size of the modulation surface of the spatial light modulator 41. In addition, in the beam modulation unit 4, the reflected light from each pixel row in FIG. 2 is collected and integrated by a lens (i.e., contracted in the minor axis direction), and is then output to the beam rotation unit 5 as a modulated beam L33. In other words, this integration of reflected light increases the power density of the modulated beam L33 irradiated onto the scanning unit 6 or the object 9. In the spatial light modulator 41, M pixels 411 (i.e., M modulation elements) constituting one pixel row constitute one modulation element 414 corresponding to one unit space. The spatial light modulator 41 functions as a modulator having N modulation elements 414 aligned in the major axis direction of the laser beam L32 on the spatial light modulator 41. In other words, the beam modulation unit 4 can modulate the intensity distribution in the major axis direction by changing the intensity of each of the N modulation elements 414 of the spatial light modulator 41.

[0022] The beam rotator 5 rotates the modulated beam L33 from the beam modulator 4 by a predetermined angle around its optical axis. The beam rotator 5 rotates the modulated beam L33 by a predetermined angle in accordance with a command from the controller 7.

[0023] The scanning unit 6 scans the surface of the object 9 held by the holding unit 11 with the modulated beam L33 from the beam rotation unit 5. That is, the scanning unit 6 projects a modulated image, which is an image of the modulated beam L33, onto the surface of the object 9 at a predetermined magnification, and moves the modulated image along the surface of the object 9. Specifically, the scanning unit 6 is a galvano scanning system, and includes a collimator lens 61, a galvano scanner 63, and a scanning lens 65 (F-θ lens).

[0024] In the scanning unit 6, the modulated image of the modulated beam L33 is collimated by a collimator lens 61 and is irradiated onto a galvanometer scanner 63. The galvanometer scanner 63 is a two-axis galvanometer scanner having two pairs of mirrors arranged in series on the modulated beam L33 and galvanometer motors that rotate the two pairs of mirrors individually.

[0025] The collimated modulated beam L33 is reflected by the galvanometer scanner 63, and its traveling direction is changed. Then, the modulated beam L33 reflected by the galvanometer scanner 63 is re-imaged by the scanning lens 65 at a position according to the rotation angle of the galvanometer scanner 63. As a result, the modulated image of the modulated beam L33 irradiated onto the surface of the object 9 moves in the scanning direction corresponding to the minor axis direction of the modulated beam L33. In this way, the surface of the object 9 is scanned with the modulated beam L33.

[0026] It is not essential that the scanning unit 6 includes the galvano scanner 63. For example, the scanning unit 6 may include a movement mechanism (a linear motor mechanism or a ball screw movement mechanism) that moves the holder 11 that holds the object 9 in the horizontal direction while the position of the modulated beam L33 is fixed.

[0027] FIG. 3 is a diagram showing the configuration of the beam rotator 5. The beam rotator 5 includes a switching unit 51, a first rotation unit 53, and a second rotation unit 55. The switching unit 51 switches the optical path of the modulated beam L33 from the beam modulator 4 between a first path and a second path. Specifically, the switching unit 51 includes a first switching mirror 511, a first switching motor 512, a first reflecting mirror 513, and a second reflecting mirror 514. The first switching mirror 511 is supported so as to rotate around a predetermined axis. The first switching motor 512 rotates the first switching mirror 511 around the predetermined axis. The first switching motor 512 is electrically connected to the control unit 7 and operates according to commands from the control unit 7. The first switching mirror 511 rotates to reflect the modulated beam L33 from the beam modulator 4 toward either the first reflecting mirror 513 arranged on the first path or the second reflecting mirror 514 arranged on the second path.

[0028] The first reflecting mirror 513 reflects the modulated beam L33 reflected by the first switching mirror 511 and guides it to the first rotation unit 53. The second reflecting mirror 514 reflects the modulated beam L33 reflected by the first switching mirror 511 again and guides it to the second rotation unit 55.

[0029] The switching unit 51 further includes a third reflecting mirror 515, a fourth reflecting mirror 516, a second switching mirror 517, and a second switching motor 518. The third reflecting mirror 515 reflects the modulated beam L33 from the first rotating unit 53, which is disposed on the first path, to the second switching mirror 517. The fourth reflecting mirror 516 reflects the modulated beam L33 from the second rotating unit 55, which is disposed on the second path, to the second switching mirror 517. The second switching mirror 517 is supported rotatably around a predetermined axis. The second switching motor 518 rotates the second switching mirror 517 around the predetermined axis. The second switching motor 518 is electrically connected to the control unit 7 and operates according to commands from the control unit 7. The second switching mirror 517 rotates to reflect the modulated beam L33 from either the first rotating unit 53 or the second rotating unit 55 toward the scanning unit 6.

[0030] The first rotation unit 53 is disposed on the first path and rotates the modulated beam L33 traveling on the first path about its optical axis, while the second rotation unit 55 is disposed on the second path and rotates the modulated beam L33 traveling on the second path about its optical axis.

[0031] The first rotation unit 53 has two rotating optical elements 531 and 533. The rotating optical elements 531 and 533 are arranged in series on the first path. The upstream rotating optical element 531 rotates the modulated beam L33 reflected by the first reflecting mirror 513 by an angle θ1 around the optical axis and guides it to the downstream rotating optical element 533. The rotating optical element 533 further rotates the modulated beam L33 from the rotating optical element 531 by an angle θ2 around the optical axis. The modulated beam L33 incident on the first rotation unit 53 is rotated by an angle ω1, which is the sum of θ1 and θ2, and is guided to the scanning unit 6.

[0032] The second rotation unit 55 also has two rotating optical elements 551 and 553. The rotating optical elements 551 and 553 are arranged in series on the second path. The upstream rotating optical element 551 rotates the modulated beam L33 reflected by the second reflecting mirror 514 by an angle θ1' around the optical axis and guides it to the downstream rotating optical element 553. The rotating optical element 553 further rotates the modulated beam L33 from the rotating optical element 551 by an angle θ2' around the optical axis. The modulated beam L33 incident on the second rotation unit 55 is rotated by an angle ω2, which is the sum of θ1' and θ2', and is guided to the scanning unit 6.

[0033] The rotating optical elements 533, 551, and 552 may have the same configuration as the rotating optical element 531. Therefore, hereinafter, an example configuration of the rotating optical element 531 will be mainly described.

[0034] 4 is a diagram showing the configuration of the rotating optical element 531 included in the beam rotation unit 5 shown in FIG. The rotating optical element 531 includes a first mirror 541, a second mirror 542, a third mirror 543, and a rotation drive unit 544. The first mirror 541 reflects the incident modulated beam L33 toward the second mirror 542. The second mirror 542 reflects the modulated beam L33 from the first mirror 541 toward the third mirror 543. The third mirror 543 reflects the modulated beam L33 from the second mirror 542.

[0035] The rotation driver 544 rotates the first mirror 541, the second mirror 542, and the third mirror 543 together. The rotation driver 544 is, for example, a cylindrical hollow motor with a cavity in the center. The first mirror 541, the second mirror 542, and the third mirror 543 are disposed in the cavity of the hollow motor. The optical axis of the modulated beam L33 incident on the first mirror 541, the optical axis of the modulated beam L33 reflected by the third mirror 543, and the rotation axis of the rotation driver 544 are all aligned. The rotation driver 544 is electrically connected to the control unit 7 and operates according to commands from the control unit 7.

[0036] In the rotating optical element 531, the rotation drive unit 544 rotates the first mirror 541, the second mirror 542, and the third mirror 543 by θ1 / 2 around the optical axis of the modulated beam L33, thereby rotating the modulated beam L33 by θ1.

[0037] In the case of the rotating optical element 531, the optical path is formed only by total reflection by three mirrors. Therefore, when the rotating optical element 531 is used, the modulated beam L33 does not need to be a collimated parallel beam.

[0038] 5 is a block diagram showing the hardware configuration of the control unit 7 shown in FIG. 1. The control unit 7 is an electronic circuit device that controls the operation of each unit in the light irradiation device 1. The control unit 7 is a computer including a processor 71 and a memory 72. The memory 72 is connected to the processor 71 via a bus wiring (not shown). The processor 71 has, for example, a CPU (Central Processor Unit). The memory 72 has a ROM (Read Only Memory), which is a read-only memory that stores a basic program, and a RAM (Random Access Memory), which is a readable and writable memory that stores various information. The memory 72 may also have storage such as a hard disk drive (HDD) or a solid state drive (SSD).

[0039] The memory 72 stores a computer program P and pattern data. The computer program P is provided to the control unit 7 via a non-transitory recording medium or a network line such as the Internet. The pattern data is data that indicates a pattern of light (e.g., figures or characters) to be irradiated onto the surface of the object 9. The irradiation process in the light irradiation device 1 progresses as the processor 71 executes processing in accordance with the computer program P and the pattern data.

[0040] The control unit 7 is electrically connected to a display 751 and an input device 753. The display 751 is a device that displays various information, and is, for example, a liquid crystal display device. The input device 753 is a device that inputs commands from the user to the control unit 7, and is, for example, a mouse and a keyboard. Note that the display 751 may function as the input device 753 by providing a touch panel on the display 751.

[0041] The control unit 7 is electrically connected to the laser light source 2, the spatial light modulator 41, the first switching motor 512, the second switching motor 518, and the four rotation drive units 544, and controls the operations of these units.

[0042] FIG. 6 is a conceptual diagram illustrating scanning of the surface of an object 9 with a modulated beam L33. In the following description, the X and Y directions are defined as being orthogonal to each other. The light irradiation device 1 scans the surface of the object 9 while rotating the modulated beam L33, which has a linear cross-sectional shape, at an arbitrary angle. The light irradiation device 1 draws a pattern on the surface of the object 9 by moving the modulated beam L33 so that it traces a trajectory along a pattern such as text or a graphic. FIG. 6 illustrates the drawing of the alphabetic characters "Z" and "A." Note that the line widths of the "Z" and "A" are smaller than the length of the rectangular beam spot Sp1 of the modulated beam L33 in the major axis direction. The intensity distribution of the beam spot Sp1 in the major axis direction is appropriately modulated according to the shape of the pattern to be drawn. The intensity distribution of the beam spot Sp1 in the minor axis direction follows a Gaussian distribution.

[0043] As shown in FIG. 6, first, the light irradiation device 1 scans along the three straight line segments Ln1, Ln2, and Ln3 that make up the letter "Z" to draw the letter "Z." First, to draw the straight line segment Ln1 extending in the X direction at the top of the letter "Z," the beam spot Sp1 is moved along a trajectory Tr1 toward the +X direction. At this time, the rotation angle is set to 0°, so that the long axis direction of the beam spot Sp1 is parallel to the Y direction and the short axis direction is parallel to the X direction. This draws the straight line segment Ln1.

[0044] Next, the light irradiation device 1 uses the beam spot Sp1 to draw a straight line segment Ln2 extending obliquely with respect to the X direction. Specifically, the beam spot Sp1 is rotated by −60° with respect to the Y direction to make the minor axis direction of the beam spot Sp1 parallel to the straight line segment Ln2. The beam spot Sp1 is then moved along the minor axis direction on a locus Tr2 to draw the straight line segment Ln2. Furthermore, the light irradiation device 1 sets the rotation angle of the beam spot Sp1 to 0° and moves the beam spot along the minor axis direction on a locus Tr3 to draw a straight line segment Ln3 extending in the X direction. In this way, the letter "Z" is drawn. After completing the drawing of the letter "Z," the light irradiation device 1 draws the next letter, "A."

[0045] "A" is also drawn by rotating the beam spot Sp1 by a predetermined angle. Specifically, the light irradiation device 1 sets the rotation angle of the beam spot Sp1 to -70° and moves the beam spot Sp1 along the minor axis direction on a locus Tr4 to draw a straight line segment Ln4. Next, the light irradiation device 1 sets the rotation angle of the beam spot Sp1 to +70° and moves the beam spot Sp1 along the minor axis direction on a locus Tr5 to draw a straight line segment Ln5. Furthermore, the light irradiation device 1 sets the rotation angle of the beam spot Sp1 to 0° and moves the beam spot Sp1 along the minor axis direction on a locus Tr6 to draw a straight line segment Ln6. As described above, in this embodiment, the beam rotation unit 5 rotates the modulated beam L33 and moves the modulated beam L33 along the minor axis direction. As a result, a pattern is drawn on the surface of the object 9 by scanning the surface of the object 9 with the modulated beam L33.

[0046] The beam rotation unit 5 is preferably configured to be able to rotate the modulated beam L33 by 180° or more. In other words, the range of the rotation angle ω1 of the first rotation unit 53 and the range of the rotation angle ω2 of the second rotation unit 55 are preferably 180° or more. By doing so, when the scanning direction of the beam spot Sp1 is set to the direction along the minor axis direction, the scanning direction can be set to any direction.

[0047] Fig. 7 is a timing chart showing the control timing of the rotation angle by the control unit 7. Fig. 7 shows the rotation angle ω1 of the first rotating unit 53 on the first path, the rotation angle ω2 of the second rotating unit 55, the rotation angle of the first switching mirror 511, and the rotation angle of the second switching mirror 517.

[0048] 7, the control unit 7 alternately switches the path of the modulated beam L33 between the first path and the second path to draw the straight line segments Ln1 to Ln6. Specifically, when drawing the straight line segments Ln1, Ln3, and Ln5, the control unit 7 switches the path of the modulated beam L33 to the second path by setting the rotation angle of the first switching mirror 511 to −45° and the rotation angle of the second switching mirror 517 to +45°. Then, the control unit 7 adjusts the rotation angle ω2 of the second rotation unit 55 to draw the straight line segments Ln1, Ln3, and Ln5. Furthermore, when drawing the straight line segments Ln2, Ln4, and Ln6, the control unit 7 switches the path of the modulated beam L33 to the first path by setting the rotation angle of the first switching mirror 511 to +45° and the rotation angle of the second switching mirror 517 to −45°. Then, the control unit 7 adjusts the rotation angle ω1 of the first rotating unit 53 as appropriate to draw the straight line segments Ln2, Ln4, and Ln6.

[0049] While drawing is being performed with the modulated beam L33 that has passed through one of the first and second paths, the control unit 7 changes the rotation angle of the rotating optical element disposed on the other path. For example, while drawing the straight line segment Ln3 is being performed, the control unit 7 changes the rotation angle ω1 of the first rotating unit 53 on the first path from −60° corresponding to the straight line segment Ln2 to −80° corresponding to the straight line segment Ln4. As a result, after drawing the straight line segment Ln3 is completed, drawing of the straight line segment Ln4 can be started simply by changing the path of the modulated beam L33 from the second path to the first path. In this way, the rotation angle of the modulated beam L33 can be quickly changed, thereby improving drawing efficiency.

[0050] Furthermore, because multiple rotating optical elements 531, 533 are arranged in series, the final rotation angle of the modulated beam L33 is the sum of the rotation angles of the rotating optical elements 531, 533. In this case, the rotation angle of each rotating optical element 531, 533 can be made smaller than when the final required rotation angle is achieved with a single rotating optical element. This reduces the time required for the rotation operation of the rotating optical elements 531, 533 to change the rotation angle of the modulated beam L33. Therefore, the rotation of the modulated beam L33 can be completed in a short time, allowing for rapid pattern writing.

[0051] Furthermore, by arranging multiple rotating optical elements 531, 533 in series, the final rotation angle can be increased even if the rotatable range of each of the rotating optical elements 531, 533 is small. In particular, to set the scanning direction arbitrarily, the rotation angle needs to be 180° or more. Therefore, by arranging multiple rotating optical elements 531, 533 in series, it becomes easy to rotate the modulated beam L33 by 180° or more.

[0052] <2. Variations> Although the embodiments have been described above, the present invention is not limited to the above and various modifications are possible.

[0053] For example, in the above embodiment, the first rotating unit 53 includes two rotating optical elements, but it may include three or more rotating elements, or may include only one rotating element. The same applies to the second rotating unit 55.

[0054] In the above embodiment, the beam rotator 5 is configured to switch the path of the modulated beam L33 between the first path and the second path and rotate the modulated beam L33 on each path. However, the beam rotator 5 may be configured with only one path. For example, the beam rotator 5 may have only the first rotator 53 by omitting the switching unit 51 and the second rotator 55.

[0055] Furthermore, in the above embodiment, the rotating optical element 531 is provided with three mirrors, but the configuration of the rotating optical element is not limited to this.

[0056] 8 is a diagram showing the configuration of a rotary optical element 531a according to a first modified example. The rotary optical element 531a has a tab prism 545 and a rotary drive unit 544 that rotates the tab prism 545. The tab prism 545 is disposed in a cavity inside the rotary drive unit 544, which is a hollow motor. The rotation axis of the rotary drive unit 544 (i.e., the rotation axis of the tab prism 545) coincides with the optical axis of the modulated beam L33 that enters the tab prism 545.

[0057] The modulated beam L33 incident on the tab prism 545 is refracted at the incident surface, totally reflected at the bottom surface, and then refracted at the exit surface. When the tab prism 545 is rotated around its longitudinal axis, the image of the exiting light from the exit surface rotates by twice the rotation angle of the tab prism 545 relative to the image of the incident light. For example, when the tab prism 545 is rotated 90°, the image of the modulated beam L33 rotates 180°. Note that because the tab prism 545 utilizes refraction, if the NA of the incident beam is large, the refraction angle changes depending on the angle of incidence, causing the emitted light beam to become distorted. For this reason, the incident beam needs to be a parallel beam that is as collimated as possible.

[0058] 9 is a diagram showing the configuration of a rotating optical element 531b according to a second modified example. The rotating optical element 531b has a polarizing beam splitter 561, two half-wave plates 562 and 563, a uniaxial retroreflecting mirror 564, and a galvanometer motor 565. The half-wave plate 563 and the uniaxial retroreflecting mirror 564 are connected to the galvanometer motor 565 and supported so as to be rotatable around a predetermined rotation axis.

[0059] When the modulated beam L33 is incident on the uniaxial retroreflecting mirror 564, the image of the modulated beam L33 rotates by twice the rotation angle of the uniaxial retroreflecting mirror 564. The incident light and reflected light of the uniaxial retroreflecting mirror 564 travel parallel paths. Therefore, the polarizing beam splitter 561 separates the modulated beam L33 incident on the uniaxial retroreflecting mirror 564 from the modulated beam L33 reflected by the uniaxial retroreflecting mirror 564 (the rotated modulated beam L33). The half-wave plates 562 and 563 control the linear polarization directions of the input light and output light so that they are orthogonal. For example, if the modulated beam L33 incident on the half-wave plate 562 from the polarizing beam splitter 561 is linearly polarized at 0°, the modulated beam L33 that passes through the half-wave plate 562 becomes right-handed circularly polarized and becomes 45° linearly polarized after passing through the half-wave plate 563. Modulated beam L33 is then reflected by uniaxial retroreflecting mirror 564 to become 135° linearly polarized light, and passes through half-wave plate 563 to become left-handed circularly polarized light. Modulated beam L33 further passes through half-wave plate 562 to become 90° linearly polarized light.

[0060] When the rotating optical element 531b is used, the drive unit for rotating the element is not limited to a hollow motor, so the degree of freedom in the configuration can be increased. In particular, when the galvanometer motor 565 is used, the uniaxial retroreflecting mirror 564 can be rotated at high speed, so the rotation angle of the modulated beam L33 can be changed at high speed. Therefore, drawing can be performed quickly.

[0061] The swing angle of a typical galvanometer motor is approximately 22.5°. In this case, one rotating optical element 531b can only rotate the modulated beam L33 by 90°. Therefore, by arranging two or more rotating optical elements 531b in series, the modulated beam L33 can be rotated by 180°.

[0062] Although the present invention has been described in detail, the above description is merely illustrative in all respects and does not limit the present invention. It is understood that countless variations not illustrated can be envisioned without departing from the scope of the present invention. The configurations described in the above embodiments and variations can be combined or omitted as appropriate as long as they are not mutually inconsistent. [Explanation of symbols]

[0063] 1 : Light irradiation device 2: Laser light source 3: Beam shaping section 4: Beam modulation section 5: Beam rotation section 6: Scanning section 9: Object 41: Spatial light modulator 51: Switching section 53: First rotating part 55: Second rotating part 531, 531a, 531b: Rotating optical element 541: 1st mirror 542: Second mirror 543: Third mirror 544: Rotation drive unit L31, L32: Laser light L33: Modulated beam

Claims

1. A light irradiation device, a light source that emits laser light; a beam shaping unit that expands the laser light from the light source in one direction; a beam modulation unit that modulates the intensity distribution of the laser light from the beam shaping unit in the one direction; a beam rotation unit having a plurality of rotating optical elements that rotate the laser light from the beam modulation unit about an optical axis; a scanning unit that scans a surface of an object with the laser light from the beam rotating unit; Equipped with The beam rotation unit includes: a switching unit that switches the path of the laser light from the beam modulation unit to either a first path or a second path; a first rotating optical element that rotates the laser light around an optical axis on the first path; a second rotating optical element that rotates the laser light around an optical axis on the second path; A light irradiation device comprising:

2. The light irradiation device according to claim 1, The first rotating optical element is a first mirror that reflects the incident laser light; a second mirror that reflects the laser light reflected by the first mirror; a third mirror that reflects the laser light reflected by the second mirror; a rotation drive unit that rotates the first mirror, the second mirror, and the third mirror together; The light irradiation device further comprises:

3. A light irradiation device that irradiates a line-shaped spot beam onto a surface of an object, a light source that emits laser light; a beam shaping unit that expands the laser light from the light source in one direction; a beam modulation unit that modulates the intensity distribution of the laser light from the beam shaping unit in the one direction; a beam rotation unit having a plurality of rotating optical elements that rotate the laser light from the beam modulation unit about an optical axis; a scanning unit that scans a surface of an object with the laser light from the beam rotating unit; Equipped with The light irradiation device, wherein the plurality of rotating optical elements are arranged in series on a path of the laser light.

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