Laser processing equipment and laser processing methods

Abstract

The laser processing apparatus (10) of the present invention comprises: a spatial light modulator (12) that receives a laser (La1) output from a laser source (11) and outputs a laser (La2) phase-modulated by a hologram; and a control unit (18) that causes the spatial light modulator (12) to present a hologram of a plurality of irradiation points (SP) on a workpiece (W) by a focusing optical system (14) focusing the phase-modulated laser (La2) output from the spatial light modulator (12) onto the workpiece (W). The control unit (18) makes at least one of the following two processing regions different in shape and size: a processing region (A) defined by a plurality of irradiation points (SP) in a first plane intersecting the optical axis of the laser (La2) irradiating the workpiece (W), and a processing region (A) defined by a plurality of irradiation points (SP) in a second plane intersecting the optical axis and separated from the first plane along the optical axis direction. Therefore, more complex processing can be performed in laser processing devices that simultaneously focus light on multiple irradiation points by using a spatial light modulator to phase-modulate the laser.

Description

Technical Field

[0001] This disclosure relates to a laser processing apparatus and a laser processing method. Background Technology

[0002] Patent Document 1 discloses a laser processing method involving laser ablation. In this laser processing method, a beam-forming device with a variable beam profile is used to irradiate each of a plurality of processing surfaces arranged along the thickness direction of the workpiece with a laser beam having a different geometric shape.

[0003] Patent Document 2 discloses technology related to a laser processing apparatus and a laser processing method. In this laser processing method, a laser emitted from a laser source is phase-modulated by a spatial phase modulation element and guided to an imaging optical system. The imaging optical system then irradiates the workpiece with the laser, processing the workpiece. As input data to the spatial phase modulation element, composite data consisting of image reconstructed hologram data showing the processed shape of the workpiece and position-shifting hologram data showing image reconstruction at a predetermined processing position is used. Furthermore, the workpiece is laser-processed while this composite data is sequentially changed.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Publication No. 2015-521108

[0007] Patent Document 2: Japanese Patent Application Publication No. 2006-119427

[0008] Non-patent literature

[0009] Non-patent document 1: F. Mezzapesa et al., "High-resolution monitoring of the hole depth during ultrafast laser ablation drilling by diode laser self-mixing interferometry", Opt. Lett. Vol. 36, pp. 822-824 (2011) Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] The object to be processed can be processed by focusing the laser light emitted from a laser source onto the object using a focusing optical system. When only a lens is used to focus the laser light, the object can be processed into the desired shape by scanning the focusing position of the laser. However, in this case, the processing takes a relatively long time.

[0012] To shorten processing time, multi-point simultaneous processing is considered, for example, by simultaneously focusing laser light onto multiple illumination points. One method for this purpose involves presenting a hologram in a phase-modulated spatial light modulator, phase-modulating a laser output from a single laser source via the spatial light modulator, and simultaneously focusing the phase-modulated laser light onto multiple illumination points via a focusing optical system. In this case, the hologram presented by the spatial light modulator has a phase modulation distribution similar to that of the laser light focused onto multiple illumination points by the focusing optical system.

[0013] In methods like those described above, it is desirable to be able to freely control the position of the irradiation point and perform more complex processing.

[0014] The purpose of this invention is to enable more complex processing in a laser processing apparatus and method that simultaneously focuses laser light onto multiple irradiation points by using a spatial light modulator to phase-modulate the laser.

[0015] means for solving problems

[0016] The present invention relates to a laser processing apparatus. The laser processing apparatus includes: a spatial light modulator that receives laser light output from a laser source, presents a hologram of the phase of the modulated laser light in each of a plurality of pixels arranged in a two-dimensional array, and outputs laser light modulated by the phase of the hologram; a focusing optical system disposed at the rear end of the spatial light modulator; and a control unit that causes the spatial light modulator to present a hologram of the phase-modulated laser light output from the spatial light modulator being focused by the focusing optical system onto a plurality of irradiation points on a workpiece, wherein the control unit causes at least one of the shapes and sizes of two processing regions to be different from each other: a processing region defined by a plurality of irradiation points in a first plane intersecting the optical axis of the phase-modulated laser light irradiating the workpiece, and a processing region defined by a plurality of irradiation points in a second plane intersecting the optical axis and separated from the first plane along the optical axis direction.

[0017] The present invention is a laser processing method. The laser processing method repeatedly performs the following steps: a control step, in each of a plurality of pixels arranged in two dimensions, causing a spatial light modulator to present a hologram of the phase of the modulated light; a light modulation step, inputting laser light output from a laser source into the spatial light modulator, and performing phase modulation of the laser light through the hologram; and a focusing step, focusing the phase-modulated laser light. In the control step, the spatial light modulator presents a hologram of the phase-modulated laser light focused on a plurality of irradiation points on the workpiece by the focusing step, such that at least one of the following two processing regions has a different shape and size: a processing region defined by a plurality of irradiation points in a first plane intersecting the optical axis of the phase-modulated laser light irradiating the workpiece, and a processing region defined by a plurality of irradiation points in a second plane intersecting the optical axis and separated from the first plane along the optical axis direction.

[0018] In the aforementioned laser processing apparatus and method, at least one of the shapes and sizes of the processing areas defined by multiple irradiation points within the first and second surfaces, which are separated from each other along the optical axis, is different. Thus, by varying the shape and / or size of the processing area on each of the multiple surfaces separated along the optical axis, more complex processing than existing methods can be performed, such as freely setting the shape of a cross-section perpendicular to the optical axis.

[0019] Invention Effects

[0020] According to embodiments of the present invention, in a laser processing apparatus and laser processing method that simultaneously focuses laser light onto multiple irradiation points by using a spatial light modulator to phase-modulate the laser, more complex processing can be performed. Attached Figure Description

[0021] Figure 1 This is a block diagram showing the structure of a laser processing apparatus 10 according to one embodiment.

[0022] Figure 2 (a) is a top view showing the phase-modulated laser La2 irradiated onto the workpiece W via the focusing optical system 14. Figure 2 (b) is a magnified view of a portion of (a).

[0023] Figure 3 Figures (a) to (e) are examples of the planar shape of the processed area A.

[0024] Figure 4 This is a block diagram showing an example of the hardware structure of the control unit 18.

[0025] Figure 5 (a) is a cross-sectional view showing the morphology of a workpiece W irradiated with laser La2, which contains multiple regions Wa, Wb, and Wc of different materials. Figure 5 (b) is a top view showing the laser-irradiated surface of the workpiece W.

[0026] Figure 6 (a) is a cross-sectional view showing the morphology of a workpiece W irradiated with laser La2, which contains multiple regions Wa, Wb, and Wc of different materials. Figure 6 (b) is a top view showing the laser-irradiated surface of the workpiece W.

[0027] Figure 7 (a) is a cross-sectional view showing the morphology of a workpiece W containing multiple regions Wd and We of different materials after being irradiated with laser La2. Figure 7 (b) to (d) are along Figure 7 Cross-sectional view of lines VIIb-VIIb, VIIc-VIIc and VIId-VIId in (a).

[0028] Figure 8 (a) is a cross-sectional view showing the morphology of the workpiece W irradiated with laser La2. Figure 8 (b) is a cross-sectional view showing the hole Ha formed in the workpiece W.

[0029] Figure 9 (a) to (c) schematically show along Figure 8 (a) is a diagram showing an example of the configuration of the irradiation points SP in each section of the IXa-IXa line, IXb-IXb line and IXc-IXc line.

[0030] Figure 10 Figures (a) to (c) are schematic diagrams showing other configurations of the irradiation points SP within each cross section.

[0031] Figure 11 (a) is a cross-sectional view showing the morphology of the workpiece W irradiated with laser La2. Figure 11 (b) is a cross-sectional view showing the hole Hb formed in the workpiece W.

[0032] Figure 12 (a) is a cross-sectional view showing the morphology of the workpiece W irradiated with laser La2. Figure 12 (b) is a cross-sectional view showing the hole Hc formed in the workpiece W.

[0033] Figure 13 (a) is a cross-sectional view showing the morphology of the workpiece W irradiated with laser La2. Figure 13 (b) is a cross-sectional view showing the holes Hc and Hd formed in the workpiece W.

[0034] Figure 14(a) is a cross-sectional view showing the morphology of the workpiece W irradiated with laser La2. Figure 14 (b) is a cross-sectional view showing the holes Hc, Hd, and He formed in the workpiece W.

[0035] Figure 15 (a) is a diagram showing the cross-sectional shape of the through hole Hf formed when the contours of the two machined regions A have curvature. Figure 15 (b) is a diagram showing the cross-sectional shape of the through hole Hg formed when the contour of a machined area A has curvature.

[0036] Figure 16 (a) is a cross-sectional view showing the hole Hh formed by irradiation with laser La2. Figure 16 (b) is a top view showing the shape of the hole Hh on one face W1 of the workpiece W. Figure 16 (c) is a top view showing the shape of the hole Hh on the other side W2 of the workpiece W.

[0037] Figure 17 This is a conceptual diagram illustrating the shape variation of the processed region A along the optical axis of laser La2, used to form the hole Hh. Figure 17 (a) shows an outline of the structure used to irradiate the workpiece W with laser La2, and a cross-section of the workpiece W along the optical axis of laser La2. Figure 17 (b) to (e) show the shape of the processing area A in the workpiece W at different depths and the multiple irradiation points SP in each face.

[0038] Figure 18 It is shown that... Figure 17 The diagram shows an example of a hologram corresponding to the surface shown in (b). Figure 18 (a) shows Figure 17 The multiple irradiation points SP shown in (b) Figure 18 (b) to (d) show the methods used to achieve Figure 18 Example of a hologram of multiple illumination points SP shown in (a).

[0039] Figure 19 It is shown that... Figure 17 The diagram shows an example of a hologram corresponding to the surface shown in (c). Figure 19 (a) shows Figure 17 The multiple irradiation points SP shown in (c) Figure 19 (b) to (d) show the methods used to achieve Figure 19 Example of a hologram of multiple illumination points SP shown in (a).

[0040] Figure 20 It is shown that... Figure 17The figure shows an example of a hologram corresponding to the surface shown in (d). Figure 20 (a) shows Figure 17 The multiple irradiation points SP shown in (d) Figure 20 (b) to (d) show the methods used to achieve Figure 20 Example of a hologram of multiple illumination points SP shown in (a).

[0041] Figure 21 It is shown that... Figure 17 The diagram shows an example of a hologram corresponding to the surface shown in (e). Figure 21 (a) shows Figure 17 The multiple irradiation points SP shown in (e) Figure 21 (b) to (d) show the methods used to achieve Figure 21 Example of a hologram of multiple illumination points SP shown in (a).

[0042] Figure 22 This is a diagram showing the shape of the irradiation point SP where laser La2 is formed at a distance greater than the workpiece W.

[0043] Figure 23 This is a flowchart illustrating one embodiment of a laser processing method.

[0044] Figure 24 This is a flowchart illustrating the case where the storage step S0 is performed before the control step S1.

[0045] Figure 25 This is a diagram used to illustrate the laser processing method described in Patent Document 1.

[0046] Figure 26 Figures (a) to (e) are used to illustrate the laser processing method described in Patent Document 2.

[0047] Figure 27 This is a diagram used to illustrate the laser processing method described in Patent Document 2. Detailed Implementation

[0048] Hereinafter, embodiments of the laser processing apparatus and laser processing method will be described in detail with reference to the accompanying drawings. Furthermore, in the description of the drawings, the same symbols are used to refer to the same elements, and repeated descriptions are omitted. Also, the present invention is not limited to these examples.

[0049] Figure 1 This is a block diagram illustrating the structure of a laser processing apparatus 10 according to one embodiment. (As shown...) Figure 1 As shown, the laser processing apparatus 10 of this embodiment includes: a laser source 11, a spatial light modulator 12, a dichroic mirror 13, a focusing optical system 14, a driving unit 15, an observation light source 16, a photodetector 17, and a control unit (PC, etc.) 18.

[0050] Laser source 11 outputs a pulsed laser La1 with a duration of less than 1 picosecond (e.g., several femtoseconds). The wavelength of the laser La1 output from laser source 11 is, for example, 250 nm or more and 2500 nm or less, and in one embodiment, 1030 nm. Furthermore, the power of the laser La1 output from laser source 11 is, for example, 0.01 W or more and 1000 W or less, and in one embodiment, 1 W. Laser source 11 is, for example, a solid-state laser having Yb:YAG crystal or Yb:KGW crystal as the laser medium, or a Yb-doped fiber laser excited by a semiconductor laser.

[0051] The spatial light modulator 12 is optically coupled to the laser source 11, and receives the laser La1 output from the laser source 11 as input. The optical coupling between the spatial light modulator 12 and the laser source 11 is, for example, spatial coupling. The spatial light modulator 12 has a plurality of pixels arranged in two dimensions, and the phase of the laser La1 is modulated independently for each pixel by presenting a hologram on the plurality of pixels.

[0052] The spatial light modulator 12 has, for example, a liquid crystal type structure. When the spatial light modulator 12 is a liquid crystal type, individual voltages constituting a hologram are applied to a plurality of pixel electrodes arranged in a two-dimensional pattern. This controls the magnitude of the electric field applied to the liquid crystal layer for each pixel electrode. The optical path length of the liquid crystal layer for each pixel varies according to the magnitude of the electric field. Therefore, the phase of the laser La1 can be modulated independently for each pixel.

[0053] The spatial light modulator 12 can be either transmissive or reflective. Furthermore, the spatial light modulator 12 is not limited to liquid crystal type; various other types of spatial light modulators can also be used. The output of the spatial light modulator 12 is laser La2, which has been phase-modulated by a hologram.

[0054] Dichroic mirror 13 is an optical element that transmits light within a certain wavelength range and reflects light within other wavelength ranges. One surface of dichroic mirror 13 is optically coupled to spatial light modulator 12. Modulated laser La2 from spatial light modulator 12 reaches dichroic mirror 13 and is reflected (or transmitted) by dichroic mirror 13 toward the workpiece W. Dichroic mirror 13 is, for example, a short-pass dichroic mirror.

[0055] Laser La2 reaches the workpiece W via a focusing optical system 14 located at the rear end of the spatial light modulator 12 (more precisely, at the rear end of the dichroic mirror 13). The focusing optical system 14, for example, is a glass lens, optically coupled to the spatial light modulator 12 via the dichroic mirror 13. The optical coupling between the spatial light modulator 12, the dichroic mirror 13, and the focusing optical system 14 is, for example, spatial coupling. The focusing optical system 14 is positioned in the optical path between the dichroic mirror 13 and the workpiece W.

[0056] The driving unit 15 is electrically connected to each pixel electrode of the spatial light modulator 12, and provides a driving voltage Vd to each pixel electrode to enable the spatial light modulator 12 to display a hologram. The driving unit 15 includes multiple voltage generation circuits electrically connected to each pixel electrode. Each voltage generation circuit includes an amplifier circuit containing a transistor.

[0057] The control unit 18 is electrically connected to the driving unit 15. The control unit 18 generates or reads a hologram from the storage unit and provides the 2D data of the hologram to the driving unit 15. The driving unit 15 generates an analog signal, i.e., a driving signal, based on the hologram for each pixel. Each amplification circuit of the driving unit 15 generates a driving voltage Vd by amplifying the driving signal.

[0058] Figure 2 (a) is a top view showing the phase-modulated laser La2 irradiated onto the workpiece W via the focusing optical system 14. Additionally, Figure 2 (b) is to Figure 2 A portion of (a) is shown in an enlarged view. (See diagram below.) Figure 2 As shown in (a), the control unit 18 generates a hologram for focusing the phase-modulated laser La2 output from the spatial light modulator 12 onto multiple irradiation points SP of the workpiece W through the focusing optical system 14, and makes the spatial light modulator 12 present the hologram.

[0059] Multiple illumination points SP define the processing area A of the workpiece W. That is, the multiple illumination points SP are arranged at intervals along a closed imaginary line B, and the processing area A is defined by the imaginary line B. Furthermore, the control unit 18 causes the spatial light modulator 12 to sequentially display multiple holograms that change the position of each illumination point SP along the imaginary line B. Thus, as... Figure 2 As shown in (b), each irradiation point SP moves discretely along the imaginary line B.

[0060] The planar shape of the processing area A, defined by multiple irradiation points SP (the shape in a plane perpendicular to the optical axis of laser La2), is set in various ways depending on the processing purpose, etc. Figure 3 This is a diagram showing an example of the planar shape of the area being processed, A. The area being processed, A, can also be as follows: Figure 3 As shown in (a), it is a circle, or it can be like... Figure 3 As shown in (b), it is elliptical. Alternatively, the processed area A can also be as follows: Figure 3 (c) shows a triangle, or it can be shown as... Figure 3 (d) shows a quadrilateral, or it can be represented as... Figure 3 (e) shows an arbitrary polygon.

[0061] The control unit 18 independently controls the light intensity (unit: W / cm) of at least two of the multiple illumination points SP.2 In other words, energy density (unit: J / cm³) 2 In one example, the control unit 18 independently controls the light intensity of each irradiation point SP. The light intensity of each irradiation point SP is determined by, for example, the processing speed of the material of the workpiece W at each irradiation point SP and / or other factors.

[0062] For example, when processing materials that are relatively fast (i.e., easy to process) compared to laser La2, reducing the light intensity slows down the processing speed. Conversely, when processing materials that are relatively slow (i.e., difficult to process) compared to laser La2, increasing the light intensity speeds up the processing speed. Thus, even when materials with varying processing speeds are mixed within the surface or cross-section of the workpiece W under light irradiation, the processing speed can be made consistent across multiple irradiation points SP. Alternatively, for materials significantly affected by heat, reducing the light intensity minimizes the area affected by the heat.

[0063] In addition, the control unit 18 controls at least one of the light intensity and irradiation time (in other words, hologram presentation time) of the multiple irradiation points SP based on the depth position of the multiple irradiation points SP of the workpiece W.

[0064] For example, compared to processing the surface of the workpiece W under light illumination, processing deeper parts of the workpiece is slower because debris or other debris left over from previous laser irradiation of La2 can obstruct the irradiation of La2. Therefore, the deeper the workpiece W is processed, the greater the light intensity of the multiple irradiation points SP and / or the longer the irradiation time, thereby improving processing speed and quality. Furthermore, when the workpiece W is composed of multiple layers of different materials (e.g., semiconductors or printed wiring substrates), laser processing can be tailored to the conditions of each layer by controlling the hologram's change cycle or presentation time.

[0065] Furthermore, in this embodiment, the workpiece W that is the object of processing can be made of various materials such as glass, semiconductors, metals (steel materials, non-ferrous metals, alloys, etc.), and composite materials (carbon fiber reinforced plastic CFRP, etc.).

[0066] Refer again Figure 1 The observation light source 16 is a laser source used to irradiate the workpiece W with the observation light Lb. The wavelength of the observation light Lb output from the observation light source 16 is different from the wavelengths of the lasers La1 and La2. The wavelength of the observation light Lb is, for example, 800 nm to 980 nm, and in one embodiment, 808 nm. The observation light source 16 is, for example, an Al(In)GaAs-based or InGaAsP-based semiconductor laser.

[0067] The observation light source 16 is optically coupled to the other side of the dichroic mirror 13. The observation light Lb from the observation light source 16 reaches the dichroic mirror 13 and passes through the dichroic mirror 13 (or is reflected) and shines on the workpiece W along a light path parallel to the laser La2.

[0068] Furthermore, in the figure, the optical axis of the observation light Lb is depicted alongside the optical axis of the laser La2, but the optical axes of the observation light Lb and the laser La2 may not be aligned. The irradiated area of ​​the workpiece W by the observation light Lb, for example, contains... Figure 2 The processed area A is shown in (a).

[0069] If a portion of the observation light Lb reaches the workpiece W, it becomes reflected light Lc, which exits from the workpiece W. Since the wavelength of the reflected light Lc is the same as that of the observation light Lb, the reflected light Lc passes through the dichroic mirror 13. The photodetector 17 is optically coupled to the other side of the dichroic mirror 13 and detects the reflected light Lc via the dichroic mirror 13.

[0070] The photodetector 17 is a 2D image detector or a detector that acquires 3D information. In the latter case, the photodetector 17 has, for example, an interferometric optical system. In this case, the photodetector 17 branches and acquires a portion of the observation light Lb output from the observation light source 16 (or the back light of the semiconductor laser of the observation light source 16), and causes this portion of the observation light Lb (or the back light) to interfere with the reflected light Lc, thereby detecting the interference light image.

[0071] The photodetector 17 is electrically connected to the control unit 18 and provides the electrical signal Sa related to the detection result to the control unit 18. In addition, an example of interferometric measurement used in this embodiment is described in Non-Patent Document 1 (F. Mezzapesa et al., Opt. Lett. Vol. 36, pp. 822-824 (2011)).

[0072] Based on the detection results from the photodetector 17, the control unit 18 determines the processing state of each illumination point SP. Furthermore, according to the processing state, the control unit 18 controls the hologram presented by the spatial light modulator 12. Here, hologram control refers to, for example, controlling the hologram presentation time or changing it to an appropriate hologram.

[0073] Figure 4 This is a block diagram illustrating an example of the hardware structure of the control unit 18. For example... Figure 4As shown, the control unit 18 is configured to include a computer, which includes hardware such as a CPU 181, RAM 182, ROM 183, input device 184, digital-to-analog converter 185, auxiliary storage device 186, and display output device 187. The control unit 18 performs the above-mentioned functions by causing these components to operate according to a program pre-stored in the auxiliary storage device 186.

[0074] Hereinafter, a processing example of the laser processing apparatus 10 of this embodiment will be described. Figure 5 (a) and Figure 6 (a) is a cross-sectional view showing the shape of a workpiece W irradiated with laser La2, which contains multiple regions Wa, Wb, and Wc of different materials. The cross-section is shown along the optical axis of laser La2 (in other words, along the thickness direction of the workpiece W). Figure 5 (b) and Figure 6 (b) is a top view showing the light-irradiated surface of the workpiece W.

[0075] In these examples, regions Wa, Wb, and Wc are arranged in a direction intersecting the optical axis of laser La2 (the thickness direction of the workpiece W), and the boundaries of regions Wa, Wb, and Wc are exposed on the light-irradiated surface. The processing speed of the material in each region Wa, Wb, and Wc differs relative to the same laser intensity of La2. Specifically, relative to the same laser intensity of La2, region Wa has the slowest processing speed, and region Wc has the fastest processing speed.

[0076] exist Figure 5 In the example shown, three independent processing areas A are set in each of the regions Wa, Wb, and Wc. Furthermore, multiple irradiation points SP are formed in region Wa to define one processing area A, multiple irradiation points SP are formed in region Wb to define the other processing areas A, and multiple irradiation points SP are formed in region Wc to define the other processing areas A.

[0077] exist Figure 6 In the example shown, a processing area A spanning regions Wa and Wb is defined, along with other processing areas A spanning regions Wb and Wc. Furthermore, multiple irradiation points SP are formed in region Wa to define a portion of one processing area A; multiple irradiation points SP are formed in region Wb to define the remaining portion of one processing area A and multiple irradiation points SP to define a portion of another processing area A; and multiple irradiation points SP are formed in region Wc to define the remaining portion of another processing area A.

[0078] In this case, such as Figure 5 (b) and Figure 6As shown in (b), the control unit 18 controls the hologram presented by the spatial light modulator 12 so that the light intensity at the illumination point SP formed in region Wa is the maximum and the light intensity at the illumination point SP formed in region Wc is the minimum. Figure 18 Furthermore, in Figure 5 (b) and Figure 6 In (b), the light intensity of each illumination point SP is represented by the shade of color. The darker the color, the greater the light intensity, and the lighter the color, the smaller the light intensity.

[0079] This allows the processing speeds of the irradiation points SP in each region Wa, Wb, and Wc to be similar, resulting in uniform processing depth. Ideally, the relative light intensities of the SP at each irradiation point are adjusted so that the processing speeds at each irradiation point SP are equal.

[0080] exist Figure 5 and Figure 6 In the example shown, the control unit 18 can also be based on Figure 1 The detection results of the photodetector 17 shown indicate the material at each illumination point SP. Since the reflectivity of the observation light Lb depends on the material, the material at each illumination point SP can be determined based on the intensity ratio of the observation light Lb to the reflected light Lc. Therefore, the boundaries of the detection regions Wa, Wb, and Wc can be determined.

[0081] Furthermore, the spatial light modulator 12 can be made to display holograms that realize the light intensities of each illumination point SP corresponding to each of the regions Wa, Wb, and Wc. In other words, in this example, the control unit 18 can generate holograms for independently setting the light intensity of each illumination point SP based on the detection results of the photodetector 17.

[0082] Alternatively, data relating to the light intensity of each irradiation point SP corresponding to the distribution of regions Wa, Wb, and Wc can be pre-stored in the storage unit (e.g., Figure 4 (as shown in ROM 183 or auxiliary storage device 186). In this case, the control unit 18 can control the light intensity of each irradiation point SP based on this data.

[0083] Figure 7 (a) is a cross-sectional view showing the shape of a workpiece W containing multiple regions Wd and We of different materials irradiated with laser La2, showing a cross-section along the optical axis of laser La2 (in other words, along the thickness direction of the workpiece W). Figure 7 (b), (c), and (d) are respectively along Figure 7 The cross-sectional view of lines VIIb-VIIb, VIIc-VIIc and VIId-VIId in (a) shows a section perpendicular to the optical axis of the laser La2.

[0084] In this example, regions Wd and We are aligned along the optical axis of laser La2, and the boundary surfaces of regions Wd and We are inclined relative to an imaginary plane perpendicular to the optical axis of laser La2. The processing speeds of the materials in each region Wd and We differ relative to laser La2 of the same intensity. Specifically, the processing speed of region Wd is slower than that of region We relative to laser La2 of the same intensity.

[0085] In this example, a processing area A is defined on the workpiece W, and multiple irradiation points SP are formed on the workpiece W to define the processing area A. Furthermore, in Figure 7 In (b), (c), and (d), the light intensity of each illumination point SP is also represented by the shade of color. The darker the color, the greater the light intensity; the lighter the color, the lower the light intensity.

[0086] Firstly, in Figure 7 As shown in (b), the processing speed at each illumination point SP in region Wd becomes arbitrary, and the control unit 18 controls the hologram presented on the spatial light modulator 12. When processing progresses to a certain depth, such as Figure 7 As shown in (c), the processed area A spans regions Wd and We. At this time, the control unit 18 controls the hologram presented on the spatial light modulator 12 in such a way that the light intensity of the illumination point SP located in region We becomes less than the light intensity of the illumination point SP located in region Wd.

[0087] As processing progresses, the proportion of We in the processed area A gradually increases, eventually reaching... Figure 7 As shown in (d), the processed area A contains only the area We. At this time, the control unit 18 controls the hologram presented on the spatial light modulator 12 in such a way that the processing speed at each illumination point SP in the area We becomes arbitrary.

[0088] In this example, the control unit 18 controls the hologram in such a way that the light intensity at the illumination point SP formed in region Wd becomes greater than the light intensity at the illumination point SP formed in region We. Therefore, at the moment when regions Wd and We are mixed in within the processed region A ( Figure 7 (c) allows the processing speeds of the irradiation points SP in each region Wd and We to be similar, resulting in uniform processing depth. Ideally, the light intensity of each irradiation point SP is adjusted so that the processing speed at each irradiation point SP is equal in the depth direction.

[0089] exist Figure 7 In the example shown, the control unit 18 can also be based on Figure 1The detection results of the photodetector 17 shown indicate changes in material properties at each illumination point SP. Since the reflectivity of the observed light Lb depends on the material, the intensity ratio of the observed light Lb to the reflected light Lc changes as the material properties change at each illumination point SP. Therefore, changes in material properties from region Wd to region We can be detected.

[0090] Furthermore, at the moment of change, the spatial light modulator 12 can present a hologram showing the change in light intensity at illumination point SP as it changes from region Wd to region We. In other words, in this example, the moment of change of the hologram used to change the light intensity at each illumination point SP can be determined based on the detection result of the photodetector 17.

[0091] Alternatively, data relating to the light intensity at each irradiation point SP, corresponding to the material distribution of the workpiece W, can be pre-stored in the storage unit (e.g., Figure 4 (as shown in ROM 183 or auxiliary storage device 186). In this case, the control unit 18 can control the light intensity of each irradiation point SP based on this data.

[0092] Figure 8 (a) is a cross-sectional view showing the shape of the workpiece W irradiated by laser La2, showing the cross-section along the optical axis of laser La2. Figure 8 (b) is a cross-sectional view showing the hole Ha formed in the workpiece W. Figure 8 In the example shown, the size of the processed region A varies continuously along the optical axis of laser La2 from the light-irradiated surface W1 of the workpiece W to its opposite surface W2. This continuous variation in size means that, in a cross-section along the optical axis of laser La2, the contour of the processed region A does not exhibit any step differences.

[0093] In this example, as processing progresses along the optical axis of laser La2 (the depth direction of the workpiece W), holograms are switched sequentially. Each hologram is formed by overlapping a hologram showing the size and shape of the processed region A within a plane intersecting the optical axis of laser La2 with a hologram showing the position of that plane along the optical axis.

[0094] Figure 9 (a), (b), and (c) schematically show along Figure 8 Example of the arrangement of irradiation points SP within each cross section of lines IXa-IXa, IXb-IXb, and IXc-IXc shown in (a). In this example, the shape of the processed area A in the cross section perpendicular to the optical axis of laser La2 is set to be circular.

[0095] in addition, Figure 10(a), (b), and (c) are schematic examples of other configurations of the irradiation point SP within each cross section. In this example, the shape of the processed region A in the cross section perpendicular to the optical axis of laser La2 is set as an arbitrary complex polygon.

[0096] Figure 9 and Figure 10 SP delineation of each irradiation point shown Figure 8 The processed area A is shown in (a). Furthermore, the shape of the processed area A in the cross-section perpendicular to the optical axis of laser La2 is not limited to... Figure 9 and Figure 10 For example, it can be set to various other shapes.

[0097] exist Figure 8 In the example shown, if the viewing angle is changed, the control unit 18 makes the sizes of the processed areas A of the IXa-IXa and IXb-IXb sections, which are separated in the optical axis direction, different. In this case, one of the IXa-IXa and IXb-IXb sections corresponds to the first surface of this embodiment, and the other corresponds to the second surface of this embodiment.

[0098] Furthermore, if other viewing angles are set, the control unit 18 makes the sizes of the processed areas A of the IXb-IXb and IXc-IXc sections, which are separated from each other in the optical axis direction, different. In this case, one of the IXb-IXb and IXc-IXc sections corresponds to the first surface of this embodiment, and the other corresponds to the second surface of this embodiment.

[0099] Furthermore, in this example, the control unit 18 also causes the spatial light modulator 12 to sequentially present an imaginary line B along the defined processing area A (see reference) at each cross section. Figure 2 (b) Multiple holograms that change the position of each irradiation point SP. Thus, each irradiation point SP moves discretely along the contour line of the processed area A.

[0100] The control unit 18 can also determine the processing status of each irradiation point SP based on the detection results from the photodetector 17, and control the presentation time of the hologram at each of the aforementioned cross sections according to the processing status. The processing status refers to, for example, the processing speed at each irradiation point SP (in other words, the progress of processing).

[0101] When the workpiece W is translucent relative to the laser La2, such as Figure 8As shown, an inverted cone-shaped (conical relative to surface W2) processing area A can also be set on the light-irradiated surface W1 of the workpiece W. In other words, the area of ​​the processing area A on one of the cross sections (IXa-IXa and IXb-IXb, or IXb-IXb and IXc-IXc) that is farther away from the light-irradiated surface W1 of the workpiece W can be larger than the area of ​​the processing area A on the other cross section.

[0102] In this case, the control unit 18 causes the spatial light modulator 12 to display a hologram that focuses the laser La2 onto each irradiation point SP, thereby cutting off the outline of the processed area A, and the processed area A falls downward from the workpiece W. Thus, as... Figure 8 As shown in (b), a through hole, namely hole Ha, is formed in the workpiece W in an inverted conical shape relative to the light-irradiated surface W1.

[0103] When the workpiece W is made of a material such as glass that is translucent relative to the laser La2, it can be processed sequentially from the side W2, which is opposite to the light-irradiated surface W1, toward the light-irradiated surface W1. This processing can be performed by making the light intensity greater than the processing threshold only at the focal point of the laser La2, and making the light intensity less than the threshold in other areas of the workpiece W (the area between the light-irradiated surface W1 and the focal point).

[0104] In this case, since laser processing can be carried out while the residue (fragments or shards) generated by laser processing falls downwards, the degree to which the residue obstructs the laser La2 irradiation is reduced.

[0105] Figure 11 (a) is a cross-sectional view showing the shape of the workpiece W irradiated by laser La2, showing the cross-section along the optical axis of laser La2. Figure 11 (b) is a cross-sectional view showing the hole Hb formed in the workpiece W. Figure 11 In the example shown, with Figure 8 Similarly, in the example shown, the size of the processed area A in the cross section perpendicular to the optical axis of laser La2 varies continuously from the light-irradiated surface W1 of the workpiece W to the surface W2 on its opposite side in the direction of the optical axis of laser La2.

[0106] Specifically, the size of the processed area A in this cross-section gradually increases as it moves away from the light-irradiated surface W1. However, in Figure 11 In the example shown, the profile of the processed region A in the cross-section along the optical axis of laser La2 becomes a shape with an inwardly convex curvature (e.g., an arc shape), rather than as... Figure 8 A straight line.

[0107] In this case, the control unit 18 causes the spatial light modulator 12 to display a hologram that focuses the laser La2 onto each irradiation point SP, thereby cutting off the outline of the processed area A and causing the processed area A to detach downwards from the workpiece W. Thus, as... Figure 11 As shown in (b), a through hole, namely hole Hb, is formed in the workpiece W in an inverted conical shape relative to the light-irradiated surface W1.

[0108] Figures 12-14 (a) is a cross-sectional view showing the shape of the workpiece W irradiated by laser La2, showing the cross-section along the optical axis of laser La2. Figures 12-14 (b) is a cross-sectional view showing the holes Hc, Hd, and He formed in the workpiece W.

[0109] In this example, firstly, as Figure 12 As shown in (a), a cone-shaped processing area A is defined, extending from approximately the center of the workpiece W along the optical axis of laser La2 to a surface W3. Furthermore, laser La2 is irradiated from another surface W4, opposite to surface W3, and... Figure 8 Similarly, in the example shown, the outline of the area to be processed, A, is cut off to form... Figure 12 The hole Hc shown in (b) is a conical (mortar-shaped) recess extending from approximately the center of the workpiece W to a face W3.

[0110] Next, as Figure 13 As shown in (a), the workpiece W is reversed vertically, and a cone-shaped processing area A is set from approximately the center of the workpiece W along the optical axis of laser La2 to another surface W4. Furthermore, laser La2 is irradiated from one surface W3, and... Figure 8 Similarly, in the example shown, the outline of the processed area A is cut off to form... Figure 13 (b) shows the hole Hd. Hole Hd is a conical (mortar-shaped) recess that extends from approximately the center of the workpiece W to another surface W4.

[0111] Finally, as Figure 14 As shown in (a), the connecting hole Hc and hole Hd are set to form other machined areas A. Furthermore, laser La2 is irradiated from surface W3 or W4, and... Figure 8 Similarly, in the example shown, the outline of the processed area A is cut off to form... Figure 14 The hole He shown in (b) thus forms a hole that passes between one surface W3 and another surface W4 of the workpiece W.

[0112] Furthermore, in the above example, the contours of each processed region A along the optical axis of laser La2 are set to be straight, but at least one of them may also have curvature. Figure 15(a) shows the cross-sectional shape of a through hole Hf formed when the two machined regions A have curvature. The through hole Hf is formed by connecting a hole Hfa that extends from approximately the center of the workpiece W to surface W3 and a hole Hfb that extends from approximately the center of the workpiece W to surface W4.

[0113] The size of the hole Hfa in the cross-section perpendicular to the optical axis of laser La2 gradually increases as it approaches surface W3 from approximately the center of the workpiece W. Similarly, the size of the hole Hfb in the cross-section perpendicular to the optical axis of laser La2 gradually increases as it approaches surface W4 from approximately the center of the workpiece W. Furthermore, the sides of these holes Hfa and Hfb have an inwardly convex curvature in the cross-section along the thickness direction of the workpiece W.

[0114] in addition, Figure 15 (b) shows the cross-sectional shape of a through hole Hg formed when the contour of a workpiece A has curvature. The through hole Hg is formed by connecting a hole Hga that extends from approximately the center of the workpiece W to surface W3 and a hole Hgb that extends from approximately the center of the workpiece W to surface W4.

[0115] The size of the hole Hga in the cross-section perpendicular to the optical axis of laser La2 gradually increases as it approaches surface W3 from approximately the center of the workpiece W. Furthermore, the side surface of hole Hga has an inwardly convex curvature in the cross-section along the thickness direction of the workpiece W. Hole Hgb and... Figure 12 The hole Hc shown and Figure 13 Similarly, the hole Hd shown is cone-shaped (mortar-shaped) when viewed from surface W4.

[0116] Figure 16 (a) is a cross-sectional view showing the hole Hh formed by irradiation with laser La2, showing a cross-section along the thickness direction of the workpiece W. Figure 16 (b) is a top view showing the shape of the hole Hh on the light-irradiated surface W1 of the workpiece W. Figure 16 (c) is a top view showing the shape of the hole Hh on the face W2, which is opposite to the light-irradiated surface W1 of the workpiece W.

[0117] In this example, the shape of the aperture Hh on the light-irradiated surface W1 (the first surface intersecting the optical axis of laser La2) is different from the shape of the aperture Hh on the opposite side of the light-irradiated surface W1 (the second surface separated from the first surface in the optical axis direction). In the example shown, the aperture Hh on the light-irradiated surface W1 is circular, while the aperture Hh on the opposite side of the surface W2 is equilateral triangular.

[0118] This type of hole Hh can be appropriately formed by the control unit 18, which makes the shapes of the processed areas A defined by multiple irradiation points on each of the light-irradiated surfaces W1 and W2 different. In one example, the cross-sectional shape of the hole Hh, which is perpendicular to the thickness direction of the workpiece W, changes continuously along the thickness direction of the workpiece W.

[0119] Figure 17 It is a conceptual illustration used to form Figure 16 The diagram shows the shape change of the processed area A along the optical axis of laser La2 in the hole Hh. Figure 17 (a) shows an outline of the structure used to irradiate the workpiece W with laser La2, and a cross section of the workpiece W in the direction of the optical axis of laser La2. Figure 17 (b), (c), (d), and (e) show the shape of the processed area A located at different depths in the workpiece W, and the multiple irradiation points SP in each face.

[0120] like Figure 17 As shown in (b), the processed area A on the light-irradiated surface W1 is circular in shape, as... Figure 17 As shown in (c) to (e), as the processed area A moves away from the light-irradiated surface W1 along the optical axis, its shape gradually changes from a circle to a triangle. Ultimately, the shape of the processed area A on surface W2 becomes a triangle. Furthermore, as described above, when the workpiece W is light-transmitting, processing can be performed from the surface W2 side towards the light-irradiated surface W1.

[0121] Figures 18-21 It is shown that... Figure 17 The diagram shows examples of holograms corresponding to each face shown in (b) to (e). Figures 18-21 (a) shows respectively Figure 17 The multiple irradiation points SP shown in (b) to (e) are shown. Figures 18-21 (b), (c), and (d) respectively show examples of holograms used to implement the multiple illumination points SP shown in (a). Furthermore, in Figures 18-21 In (b), (c), and (d), the intensity of the color indicates the phase size; the darker the color, the smaller the phase (close to 0 radians), and the lighter the color, the larger the phase (close to 2π radians).

[0122] In addition, Figures 18-21 In the figures, (b), (c), and (d) show the outline used along the processed area A. Figure 2The imaginary line B) shows multiple holograms that change the position of each illumination point SP. As shown by the arrows in the figure, the control unit 18 performs processing by periodically and repeatedly presenting each hologram shown in (b), (c), and (d) relative to the spatial light modulator 12, thereby moving the position of each illumination point SP along the outline of the processed area A.

[0123] exist Figures 7 to 17 In the processing examples shown, the hologram needs to be changed midway through the laser processing. Furthermore, when changing the hologram, it is necessary to retrieve data from the storage unit (e.g., ...). Figure 4 The ROM 183 or auxiliary storage device 186 shown can recall the hologram to be presented later, or the time to generate the hologram to be presented later can be calculated based on the detection result of the photodetector 17.

[0124] During the period from the removal of a hologram to the presentation of other holograms, the control unit 18 causes the spatial light modulator 12 to present a hologram in which the light intensity of laser La2 is set to be less than a processing threshold at any location on the workpiece W. For example, such as Figure 22 As shown, the control unit 18 can also cause the spatial light modulator 12 to display a hologram, such as the irradiation point SP of the laser La2 being formed at a distance greater than the workpiece W. This achieves an effect equivalent to setting the laser source 11 to an off state.

[0125] In addition, Figures 8 to 17 In the processing examples shown, within each plane arranged along the optical axis of laser La2, there is also... Figures 5-7 Similarly, in the processing examples shown, the control unit 18 can also independently control the light intensity of multiple irradiation points SP for each irradiation point SP. In addition, the control unit 18 can also independently control the light intensity of irradiation points SP arranged in the optical axis direction on each surface.

[0126] For example, in Figures 8-10 In the example shown, the light intensity at the irradiation point SP on sections IXa-IXa, IXb-IXb, and IXc-IXc can be set independently for each section based on its material (or processing speed). Furthermore, the irradiation time for each section can also be set independently.

[0127] Figure 23 This is a flowchart illustrating the laser processing method of this embodiment. This laser processing method can be performed using the laser processing apparatus 10 described above. Figure 23As shown, firstly, as a control step S1, the spatial light modulator 12 presents a hologram of the phase of the modulated light in each of the multiple pixels arranged in two dimensions. Next, as a light modulation step S2, the laser La1 output from the laser source 11 is input into the spatial light modulator 12, and the phase of the laser La1 is modulated by the hologram. Furthermore, as a focusing step S3, the phase-modulated laser La2 is focused using the focusing optical system 14.

[0128] In the preceding control step S1, the spatial light modulator 12 presents a hologram of multiple irradiation points SP on the workpiece W, which is formed by focusing the phase-modulated laser La2 through the focusing step S3. This creates multiple irradiation points SP on the workpiece W, and processing (melting, cracking, cutting, etc.) is performed at each irradiation point SP. Furthermore, as a light detection step S4, an observation light Lb having a wavelength different from that of the laser La2 is irradiated onto the workpiece W, and the observation light reflected from the workpiece W (reflected light Lc) is detected.

[0129] Subsequently, while changing the hologram, steps S1 to S4 are repeated. In control step S1, as follows... Figure 2 As shown, the spatial light modulator 12 sequentially presents multiple holograms in which the positions of each illumination point SP are changed along an imaginary line B that defines the processing area A. Furthermore, if the difference between the set target value of the light intensity at the illumination point SP and the detection result of the observed light is greater than the target error (step S5: NO), the hologram can be corrected (step S6).

[0130] like Figures 5-7 As shown, in control step S1, the light intensity of multiple illumination points SP is independently controlled for each illumination point SP. Alternatively, as... Figures 8 to 17 As shown, in control step S1, for each of the plurality of surfaces intersecting the optical axis of laser La2, the shape of the processed area A defined by the plurality of irradiation points SP is made different. Alternatively, in control step S1, the light intensity of the plurality of irradiation points SP is controlled independently for each irradiation point SP, and for each of the plurality of surfaces intersecting the optical axis of laser La2, the shape of the processed area A defined by the plurality of irradiation points SP is made different.

[0131] In the case of independently controlling the light intensity of each illumination point SP, in the control step S1, based on the detection results of the previous light detection step S4, the change of material at each illumination point SP is detected, and the light intensity of each illumination point SP is changed according to the change of material.

[0132] Or, such as Figure 24As shown, a storage step S0 is performed before the control step S1. In the storage step S0, data related to the light intensity of each irradiation point SP corresponding to the material distribution of the workpiece W are pre-stored in the storage unit (e.g., Figure 4 (as shown in ROM 183 or auxiliary storage device 186). Furthermore, in control step S1, the light intensity of each illumination point SP is controlled based on this data. Additionally, if the difference between the set target value of the light intensity of the illumination point SP and the detection result of the observed light is greater than the target error (step S5: NO), the hologram can be corrected (step S6).

[0133] Furthermore, when the shape of the processed area A is different for each of the multiple surfaces intersecting the optical axis of laser La2, it is also possible to achieve the following: Figures 8-15 As shown, the shape of the processed area A is continuously varied along the optical axis of the laser La2. This can also be achieved when the workpiece W is translucent to the laser La2. Figures 8-15 As shown, the area of ​​the processed region A on the surface that is farther away from the light-irradiated surface W1 of the workpiece W is greater than the area of ​​the processed region A on the surface that is closer to the light-irradiated surface W1.

[0134] The processing status at each illumination point SP can also be determined based on the detection results in the photodetector step S4, and the presentation time of the hologram for each surface can be controlled according to the processing status. Alternatively, the light intensity of multiple illumination points SP can be controlled independently for each surface.

[0135] In addition, during the control step S1, when changing the hologram, during the period from eliminating a certain hologram to presenting other holograms, the spatial light modulator 12 presents a hologram in which the light intensity of the laser La2 is set to be less than the processing threshold at any part of the workpiece W.

[0136] The effects obtained by the laser processing apparatus 10 and laser processing method of this embodiment as described above will be explained.

[0137] In the laser processing apparatus 10 and laser processing method of this embodiment, at least two surfaces separated from each other in the optical axis direction have different shapes and sizes for the processed region A. Thus, by varying the shape and / or size of the processed region A on each of the plurality of surfaces separated in the optical axis direction, more complex processing than existing methods can be performed, such as freely setting the shape of a cross-section perpendicular to the optical axis direction.

[0138] Furthermore, according to this embodiment, the adjustment of light intensity at each irradiation point SP, the disconnection / connection of each irradiation point SP, and the movement of each irradiation point SP along the imaginary line B can be achieved without using any mechanical components. Therefore, the structure of the laser processing apparatus 10 can be greatly simplified, and processing can be performed at high speed and with high precision.

[0139] As in this embodiment, the workpiece W may be translucent relative to the phase-modulated laser La2, and the area of ​​the processed region A on the surface farther from the light-irradiated surface W1 of the workpiece W may be larger than the area of ​​the processed region A on the surface closer to it. In this case, complex processing, such as forming an inverted conical hole with an aperture that expands as it moves away from the light-irradiated surface W1 of the workpiece W, can be easily performed.

[0140] In this embodiment, the control unit 18 (in control step S1) may also cause at least one of the shape and size of the processed area A to continuously change in the optical axis direction of the laser La2. In this case, it is easy to process holes and the like, whose cross-sectional shape is perpendicular to the optical axis direction and smoothly deformed in the optical axis direction.

[0141] As in this embodiment, the control unit 18 (in control step S1) may also cause the spatial light modulator 12 to sequentially present multiple holograms of each of the multiple surfaces arranged in the optical axis direction, wherein the position of each illumination point SP is changed along the hypothetical line B that defines the processing area A. In this case, sufficient light intensity is imparted to each illumination point SP, and through a single hologram... Figure 1 Compared to the case of secondary irradiation with laser La2, the output power required by laser source 11 can be reduced, which can help to miniaturize laser source 11.

[0142] As in this embodiment, the laser processing apparatus 10 may also include: an observation light source 16 that illuminates the workpiece W with observation light Lb; and a photodetector 17 that detects the observation light reflected from the workpiece W, i.e., the reflected light Lc. Additionally, the laser processing method may further include: a photodetection step S4, in which the observation light Lb is illuminated on the workpiece W, and the reflected light Lc from the workpiece W is detected.

[0143] Furthermore, the control unit 18 (in control step S1) can also determine the processing state at each irradiation point SP based on the detection results from the photodetector 17 (detection step S4), and control the presentation time of the hologram for each surface according to the processing state. Alternatively, the control unit 18 (in control step S1) can also detect changes in the material of each irradiation point SP based on the detection results from the photodetector 17, and change the light intensity of each irradiation point SP according to the changes in material. In these cases, processing accuracy can be further improved.

[0144] As in this embodiment, the control unit 18 (in control step S1) can also independently control the light intensity of at least two irradiation points SP included in the plurality of irradiation points SP on each surface. In this case, when there are differences in the material of a part of the workpiece W, that is, when there are differences in the processing speed relative to the same intensity of laser La2, laser La2 can be irradiated with an appropriate light intensity at each irradiation point SP corresponding to each part. Therefore, workpiece W made of two or more materials can be easily processed into complex shapes.

[0145] In this embodiment, the control unit 18 (in control step S1) may also independently control the light intensity of the irradiation point SP in at least two surfaces. In this case, when there are differences in the materials constituting each surface, that is, when there are differences in the processing speed relative to the laser La2 of the same intensity, the laser La2 can be irradiated with an appropriate light intensity according to the material of each surface.

[0146] In this embodiment, the control unit 18 (in control step S1) may also, when a hologram needs to be changed, cause the spatial light modulator 12 to present a hologram in which the light intensity of laser La2 is set to be less than the processing threshold at any part of the workpiece W during the period from the elimination of a certain hologram to the presentation of other holograms. In this case, compared with the case where laser La2 is blocked by a mechanical mechanism such as a shutter, since there is no need for the mechanical shutter itself or the high-voltage device required to operate the mechanical shutter, the structure of the laser processing apparatus 10 can be simplified, which helps to miniaturize the laser processing apparatus 10 and reduce its cost.

[0147] As in this embodiment, the laser processing apparatus 10 may also include a storage unit that pre-stores data related to the light intensity of each irradiation point SP corresponding to the material distribution of the workpiece W, and the control unit 18 controls the light intensity of each irradiation point SP based on this data. Alternatively, the laser processing method may include a storage step S0 before the control step S1, whereby data related to the light intensity of each irradiation point SP corresponding to the material distribution of the workpiece W is pre-stored, and the light intensity of each irradiation point SP is controlled based on this data in the control step S1. In these cases, since the required light intensity for each irradiation point SP can be obtained quickly, the hologram modification time can be shortened.

[0148] Examples of existing laser processing methods are given for illustration. Figure 25 This diagram illustrates the laser processing method described in Patent Document 1. This laser processing method involves ablation of a workpiece (workpiece) 110 having a processing surface 112 using laser ablation, forming a three-dimensional geometric shape 114 within the workpiece 110.

[0149] Figure 25Three different beam profiles 116, 118, and 120 are shown. In each beam profile 116, 118, and 120, the vertical axis represents light intensity, and the horizontal axis represents position. In each beam profile 116, 118, and 120, the laser beam has a pattern of an irradiated area 122 and a non-irradiated area 124 at the location of the processed surface 112. In the irradiated area 122, the light intensity is higher than the ablation threshold. In the non-irradiated area 124, the light intensity is lower than the dissolution threshold of the material of the workpiece 110.

[0150] Each beam profile 116, 118, 120 is different in terms of its diameter, equivalent diameter, and / or geometry. That is, beam profiles 116, 118, 120 have successively smaller diameters or equivalent diameters. Furthermore, as shown in the cross-sectional view of the partial notch in workpiece 110, these beam profiles 116, 118, 120 may have different geometries. Therefore, a stepped geometry is produced in workpiece 110.

[0151] However, in the method described in Patent Document 1, since the area irradiated by a single laser is relatively large, a laser source with extremely high output power is required to cover the entire area above the ablation threshold. This results in a large laser source. Furthermore, since the diameter of the beam profile generally decreases as processing progresses, the shapes that can be formed are limited. Moreover, when the workpiece 110 contains a mixture of various materials with different processing speeds, it is difficult to set the light intensity and irradiation time according to the properties of each material.

[0152] Regarding these issues, the laser processing apparatus 10 and laser processing method of this embodiment, since the laser La2 is focused onto multiple irradiation points SP for processing, only a small output power of the laser source 11 is needed, which helps to miniaturize the laser source 11. Furthermore, it is also easy to perform, for example... Figure 8 The inverted conical hole Ha shown, or Figure 16 The machining of complex shapes such as the hole Hh shown.

[0153] Furthermore, since the light intensity and irradiation time are independently controlled at each irradiation point (SP), the light intensity and irradiation time can be easily set according to the properties of each material even when the processed area contains a mixture of various materials. In addition, the elimination of optical components such as λ / 2 plates or beam splitters for adjusting light intensity further simplifies the structure of the laser processing equipment.

[0154] Figure 26 and Figure 27 This diagram illustrates the laser processing method described in Patent Document 2. In this laser processing method, multiple image reconstructing hologram data are prepared and then laser processing is performed. Specifically, as follows... Figure 26As shown in (a), the surface to be processed 200 is divided into multiple units 201, such that one irradiation point 202 corresponds to one unit 201, and it is free to choose whether to form an irradiation point 202 for each unit 201.

[0155] The position-shifting hologram data is superimposed on the image reconstructing hologram data. Furthermore, the image is formed on the processing surface 200 while the position-shifting hologram data is being modified. Figure 26 The discrete point images shown in (b) to (e) are obtained, thus yielding Figure 27 The complex shape shown is the processed shape 203.

[0156] However, in the method described in Patent Document 2, since the light intensity of each irradiation point 202 is not controlled individually, it is difficult to set the light intensity and irradiation time according to the properties of each material when the surface being processed 200 is mixed with multiple materials with different processing speeds.

[0157] In contrast, according to the laser processing apparatus 10 and laser processing method of this embodiment, since the light intensity and irradiation time are independently controlled for each irradiation point SP, the light intensity and irradiation time can be easily set according to the properties of each material when multiple materials are mixed in the processing area.

[0158] The laser processing apparatus and method are not limited to the embodiments and structural examples described above, and various other variations are possible. For example, in the above embodiments, it was described that when the processed area A contains multiple materials, processing corresponding to the light intensity of each material property becomes possible by independently controlling the light intensity at each irradiation point SP. Not limited to this example, for instance, even when the processed area A is composed of a single material, by independently controlling the light intensity at each irradiation point SP, the removal rate (removal amount) of the workpiece W can be independently controlled for each part of the processed area A, and more complex shapes can be achieved.

[0159] Furthermore, while the above embodiments illustrate the case where the light intensity of multiple illumination points SP is controlled independently, it is also possible to independently control the light intensity of at least two of the multiple illumination points SP when it is not necessary to control all illumination points SP independently. In this case, the effects of the above embodiments can also be achieved.

[0160] The laser processing apparatus of the above embodiment is configured to include: a spatial light modulator that receives laser light output from a laser source, presents a hologram of the phase of the modulated laser light in each of a plurality of pixels arranged in two dimensions, and outputs laser light modulated by the phase of the hologram; a focusing optical system disposed at the rear end of the spatial light modulator; and a control unit that causes the spatial light modulator to present a hologram of the phase-modulated laser light output from the spatial light modulator being focused by the focusing optical system onto a plurality of irradiation points on a workpiece, and the control unit causes at least one of the shapes and sizes of the following two processing regions to be different from each other: a processing region defined by a plurality of irradiation points in a first surface intersecting the optical axis of the phase-modulated laser light irradiating the workpiece, and a processing region defined by a plurality of irradiation points in a second surface intersecting the optical axis and separated from the first surface along the optical axis direction.

[0161] The laser processing method described above is configured to repeatedly perform: a control step, in each of a plurality of pixels arranged in two dimensions, causing a spatial light modulator to present a hologram of the phase of the modulated light; a light modulation step, inputting a laser beam output from a laser source into the spatial light modulator and performing phase modulation of the laser beam through the hologram; and a focusing step, focusing the phase-modulated laser beam. In the control step, the spatial light modulator presents a hologram of the phase-modulated laser beam focused on a plurality of irradiation points on the workpiece by the focusing step, and at least one of the following two processing regions has a different shape and size: a processing region defined by a plurality of irradiation points in a first surface intersecting the optical axis of the phase-modulated laser beam irradiating the workpiece, and a processing region defined by a plurality of irradiation points in a second surface intersecting the optical axis and separated from the first surface along the optical axis direction.

[0162] The aforementioned laser processing apparatus may also be configured such that the workpiece is translucent to the phase-modulated laser, and the area of ​​the processed region on the side farther from the light-irradiated surface of the workpiece in the first and second surfaces is larger than the area of ​​the processed region on the other side.

[0163] The laser processing method described above can also be configured such that the workpiece is translucent relative to the phase-modulated laser, and in the control step, the area of ​​the processed region on the side farther from the light-irradiated surface of the workpiece in the first and second surfaces is greater than the area of ​​the processed region on the other side.

[0164] Based on this structure, complex processes such as forming inverted conical holes with an aperture that expands as light travels away from the surface of the workpiece can be easily performed.

[0165] In the aforementioned laser processing apparatus, the control unit may also be configured such that at least one of the shape and size of the processed area continuously changes in the direction of the optical axis.

[0166] In the laser processing method described above, it can also be configured such that, in the control step, at least one of the shape and size of the processed area continuously changes in the direction of the optical axis.

[0167] Based on this structure, it is easy to process holes and the like with a cross-sectional shape that is perpendicular to the optical axis and smoothly deformed in the optical axis direction.

[0168] In the aforementioned laser processing apparatus, the control unit may also be configured such that the spatial light modulator sequentially presents multiple holograms on the first and second surfaces, each having a position of an irradiation point that changes along an imaginary line defining the processing area.

[0169] In the above-mentioned laser processing method, it can also be configured such that, in the control step, the spatial light modulator sequentially presents multiple holograms in the first and second surfaces, each of which changes the position of each irradiation point along an imaginary line defining the area to be processed.

[0170] Based on this structure, sufficient light intensity is imparted to each illumination point and through a single hologram. Figure 1 Compared to the case of secondary laser irradiation, this method can reduce the output power required by the laser source and can help to miniaturize the laser source.

[0171] The aforementioned laser processing apparatus may also be configured to further include: an observation light source that irradiates the workpiece with observation light; and a photodetector that detects the observation light reflected from the workpiece. Based on the detection results of the photodetector, the control unit determines the processing status at each irradiation point and controls the presentation time of the holograms on the first and second surfaces according to the processing status.

[0172] The laser processing method described above may also include: a photodetection step, in which observation light is irradiated onto the workpiece and the observation light reflected from the workpiece is detected; and in a control step, based on the detection results in the photodetection step, the processing status at each irradiation point is determined, and the presentation time of the holograms on the first and second surfaces is controlled according to the processing status.

[0173] This structure allows for further improvement in machining accuracy.

[0174] In the aforementioned laser processing apparatus, the control unit is configured to independently control the light intensity of at least two irradiation points included in the plurality of irradiation points on each surface.

[0175] In the above-mentioned laser processing method, it can also be configured such that, in the control step, the light intensity of at least two irradiation points included in the plurality of irradiation points in each surface is controlled independently.

[0176] Based on this structure, when there are differences in the material of the workpiece, i.e., when there are differences in the processing speed relative to the same laser intensity, the laser can be irradiated with an appropriate light intensity at each irradiation point corresponding to each part. Therefore, workpieces composed of two or more materials can be easily processed into complex shapes. In addition, even when the processed area is composed of a single material, the removal rate (removal amount) of the workpiece can be independently controlled by independently controlling the light intensity at each irradiation point, thus enabling the realization of more complex shapes.

[0177] In the aforementioned laser processing apparatus, the control unit independently controls the light intensity of multiple irradiation points on the first surface and the light intensity of multiple irradiation points on the second surface.

[0178] In the aforementioned laser processing method, the light intensity of multiple irradiation points on the first surface and the light intensity of multiple irradiation points on the second surface are controlled independently during the control step.

[0179] Based on this structure, when the materials constituting the first and second surfaces are different, that is, when the processing speed relative to the same intensity of laser is different, the laser can be irradiated with an appropriate light intensity according to the material of each surface.

[0180] In the aforementioned laser processing apparatus, the control unit may also be configured such that, when changing a hologram, during the period from the elimination of a certain hologram to the presentation of other holograms, the spatial light modulator presents a hologram in which the light intensity of the laser is set to be less than the processing threshold at any part of the workpiece.

[0181] In the above-mentioned laser processing method, it can also be configured such that, in the control step, when changing the hologram, during the period from the elimination of a certain hologram to the presentation of other holograms, the spatial light modulator presents a hologram in which the light intensity of the laser is set to be less than the processing threshold at any part of the workpiece.

[0182] This structure simplifies the laser processing device compared to methods that use mechanical mechanisms like shutters to block the laser.

[0183] [Industry availability]

[0184] This invention can be used as a laser processing apparatus and laser processing method that enables more complex processing in a structure that simultaneously focuses light onto multiple irradiation points by using a spatial light modulator to modulate the laser phase.

[0185] Symbol Explanation

[0186] 10…Laser processing apparatus; 11…Laser source; 12…Spatial light modulator; 13…Dial mirror; 14…Focusing optical system; 15…Drive unit; 16…Observation light source; 17…Photodetector; 18…Control unit; 110…Workpiece; 112…Processed surface; 114…Geometry; 116, 118, 120…Beam profile; 122:Irradiated area; 124…Non-irradiated area; 181…CPU; 182…RAM; 183…ROM; 184…Input device; 185…Digital-to-analog converter; 186…Auxiliary storage device; 200…Workpiece surface; 201…Cell; 202…Irradiation point; 203…Workpiece shape; A…Workpiece area; B…Imaginary line; Ha, Hb, Hc, Hd, He, Hh…Hole; Hf, Hg…Through hole; Hfa, Hfb, Hga, Hgb…Hole; La1, La2…Laser; Lb…Observation light; Lc…Reflected light; Sa…Signal; SP…Irradiation point; Vd…Drive voltage; W…Workpiece; W1…Irradiated surface; W2, W3, W4…Surface; Wa, Wb, Wc, Wd, We…Region.

Claims

1. A laser processing apparatus, comprising: A spatial light modulator takes as input a laser beam output from a laser source, presents a hologram of phase modulation of the laser beam in each of multiple pixels arranged in a two-dimensional array, and outputs a laser beam modulated by the phase of the hologram. A focusing optical system, which is disposed at the rear end of the spatial light modulator; and The control unit enables the spatial light modulator to display a hologram in which the phase-modulated laser output from the spatial light modulator is simultaneously focused onto multiple illumination points on the workpiece by the focusing optical system. The control unit ensures that at least one of the following two processing areas has a different shape and size: a processing area defined by the plurality of irradiation points in a first plane intersecting the optical axis of the phase-modulated laser irradiating the workpiece, and a processing area defined by the plurality of irradiation points in a second plane intersecting the optical axis and separated from the first plane along the direction of the optical axis. The control unit independently controls the light intensity of at least two of the multiple illumination points within each surface, and The control unit independently controls the light intensity of the plurality of irradiation points in the first surface and the light intensity of the plurality of irradiation points in the second surface according to the depth position of each surface.

2. The laser processing apparatus according to claim 1, wherein, The workpiece is transmissive to the phase-modulated laser. The area of ​​the processed region on the side that is farther from the light-irradiated surface of the workpiece in the first and second sides is greater than the area of ​​the processed region on the other side.

3. The laser processing apparatus according to claim 1, wherein, The control unit causes at least one of the shape and size of the processed area to change continuously in the direction of the optical axis.

4. The laser processing apparatus according to claim 2, wherein, The control unit causes at least one of the shape and size of the processed area to change continuously in the direction of the optical axis.

5. The laser processing apparatus according to any one of claims 1 to 4, wherein, The control unit causes the spatial light modulator to sequentially display multiple holograms on each of the first and second surfaces, in which the position of each irradiation point is changed along an imaginary line defining the processed area.

6. The laser processing apparatus according to any one of claims 1 to 4, wherein, It also has: An observation light source that illuminates the workpiece; and A photodetector that detects the observed light reflected from the workpiece. The control unit determines the processing status at each irradiation point based on the detection results of the photodetector, and controls the presentation time of the holograms on the first and second surfaces according to the processing status.

7. The laser processing apparatus according to claim 5, wherein, It also has: An observation light source that illuminates the workpiece; and A photodetector that detects the observed light reflected from the workpiece. The control unit determines the processing status at each irradiation point based on the detection results of the photodetector, and controls the presentation time of the holograms on the first and second surfaces according to the processing status.

8. The laser processing apparatus according to any one of claims 1 to 4, wherein, When the control unit changes the hologram, during the period from eliminating a certain hologram to presenting other holograms, it causes the spatial light modulator to present a hologram in which the light intensity of the laser is set to be less than the processing threshold at any part of the workpiece.

9. The laser processing apparatus according to claim 5, wherein, When the control unit changes the hologram, during the period from eliminating a certain hologram to presenting other holograms, it causes the spatial light modulator to present a hologram in which the light intensity of the laser is set to be less than the processing threshold at any part of the workpiece.

10. The laser processing apparatus according to claim 6, wherein, When the control unit changes the hologram, during the period from eliminating a certain hologram to presenting other holograms, it causes the spatial light modulator to present a hologram in which the light intensity of the laser is set to be less than the processing threshold at any part of the workpiece.

11. The laser processing apparatus according to claim 7, wherein, When the control unit changes the hologram, during the period from eliminating a certain hologram to presenting other holograms, it causes the spatial light modulator to present a hologram in which the light intensity of the laser is set to be less than the processing threshold at any part of the workpiece.

12. A laser processing method, wherein, Repeat: The control steps involve making the spatial light modulator present a hologram of the phase of the modulated light in each of the multiple pixels arranged in a two-dimensional array. In the optical modulation step, the laser output from the laser source is input into the spatial light modulator, and the phase of the laser is modulated through the hologram; and The focusing step involves focusing the phase-modulated laser light. In the control step, the spatial light modulator produces a hologram by simultaneously focusing the phase-modulated laser light onto multiple illumination points of the workpiece through the focusing step. The two processed regions are to be at least different in shape and size, namely, a processed region defined by the plurality of irradiation points in a first plane intersecting the optical axis of the phase-modulated laser irradiating the workpiece, and a processed region defined by the plurality of irradiation points in a second plane intersecting the optical axis and separated from the first plane along the direction of the optical axis. In the control step, the light intensity of at least two of the plurality of illumination points within each surface is controlled independently, and In the control step, the light intensity of the plurality of irradiation points in the first surface and the light intensity of the plurality of irradiation points in the second surface are controlled independently of each other according to the depth position of each surface.

13. The laser processing method according to claim 12, wherein, The workpiece is transmissive to the phase-modulated laser. In the control step, the area of ​​the processed region on the side that is farther away from the light-irradiated surface of the workpiece in the first and second surfaces is made larger than the area of ​​the processed region on the other side.

14. The laser processing method according to claim 12, wherein, In the control step, at least one of the shape and size of the processed area is continuously varied in the direction of the optical axis.

15. The laser processing method according to claim 13, wherein, In the control step, at least one of the shape and size of the processed area is continuously varied in the direction of the optical axis.

16. The laser processing method according to any one of claims 12 to 15, wherein, In the control step, the spatial light modulator sequentially presents multiple holograms on each of the first and second surfaces, in which the positions of each illumination point are changed along an imaginary line defining the area to be processed.

17. The laser processing method according to any one of claims 12 to 15, wherein, It also includes: a light detection step, wherein observation light is shone onto the workpiece, and the observation light reflected from the workpiece is detected. In the control step, based on the detection results in the light detection step, the processing status at each irradiation point is determined, and the presentation time of the holograms on the first and second surfaces is controlled according to the processing status.

18. The laser processing method according to claim 16, wherein, It also includes: a light detection step, wherein observation light is shone onto the workpiece, and the observation light reflected from the workpiece is detected. In the control step, based on the detection results in the light detection step, the processing status at each irradiation point is determined, and the presentation time of the holograms on the first and second surfaces is controlled according to the processing status.

19. The laser processing method according to any one of claims 12 to 15, wherein, In the control step, when changing a hologram, during the period from eliminating a hologram to presenting other holograms, the spatial light modulator presents a hologram in which the light intensity of the laser is set to be less than the processing threshold at any part of the workpiece.

20. The laser processing method according to claim 16, wherein, In the control step, when changing a hologram, during the period from eliminating a hologram to presenting other holograms, the spatial light modulator presents a hologram in which the light intensity of the laser is set to be less than the processing threshold at any part of the workpiece.

21. The laser processing method according to claim 17, wherein, In the control step, when changing a hologram, during the period from eliminating a hologram to presenting other holograms, the spatial light modulator presents a hologram in which the light intensity of the laser is set to be less than the processing threshold at any part of the workpiece.

22. The laser processing method according to claim 18, wherein, In the control step, when changing a hologram, during the period from eliminating a hologram to presenting other holograms, the spatial light modulator presents a hologram in which the light intensity of the laser is set to be less than the processing threshold at any part of the workpiece.

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