Laser processing apparatus and laser processing method

Abstract

The laser processing apparatus (10) of the present application is provided with: a spatial light modulator (12) that inputs laser light (La1) output from a laser light source (11) and outputs laser light (La2) phase-modulated by a hologram; and a control section (18) that causes the spatial light modulator (12) to exhibit a hologram that condenses the phase-modulated laser light (La2) output from the spatial light modulator (12) by a condensing optical system (14) to a plurality of irradiation points (SP) of a workpiece (W). The control section (18) controls the light intensity of at least two irradiation points (SP) included in the plurality of irradiation points (SP) independently of each other. Thus, in the laser processing apparatus that simultaneously performs condensing irradiation to a plurality of irradiation points by phase-modulating laser light using a spatial light modulator, more complex processing can be performed.

Description

Technical Field

[0001] The present disclosure relates to a laser processing device and a laser processing method. Background Art

[0002] Patent Document 1 discloses a technology related to a laser processing method using laser ablation. In this laser processing method, a beam shaping device capable of changing the beam profile is used to irradiate a plurality of processing surfaces arranged along the thickness direction of the workpiece with a laser beam having a beam profile having a different geometric shape.

[0003] Patent Document 2 discloses technologies related to a laser processing apparatus and a laser processing method. In this laser processing method, laser light emitted from a laser source is phase-modulated by a spatial phase modulation element and guided to an imaging optical system. This imaging optical system then irradiates the laser light onto a workpiece, thereby processing the workpiece. The input data for the spatial phase modulation element uses composite data consisting of image reconstruction hologram data that reconstructs the processed shape of the workpiece and position-shifted hologram data that reconstructs the image at a predetermined processing position. Laser processing of the workpiece is performed while sequentially varying this composite data.

[0004] Prior art literature

[0005] Patent Literature

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

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

[0008] Non-patent literature

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

[0010] Problems to be solved by the invention

[0011] Laser light emitted from a laser source is focused by a focusing optical system and then irradiated onto an object to be processed. When focusing the laser light using only a lens, the object can be processed into the desired shape by scanning the laser's focused position. However, in this case, processing takes a long time.

[0012] To shorten processing time, one approach is to simultaneously focus laser light on multiple irradiation points, for example, to perform multi-point simultaneous processing. One method for this purpose involves creating a hologram on a phase-modulation spatial light modulator, phase-modulating laser light output from a single laser source using the spatial light modulator, and then simultaneously focusing this phase-modulated laser light on multiple irradiation points using a focusing optical system. In this case, the hologram created by the spatial light modulator has a phase modulation distribution similar to that achieved by focusing laser light on multiple irradiation points using a focusing optical system.

[0013] In the above-mentioned method, it is desired to freely control the position of the irradiation point and perform more complex processing.

[0014] An object of the present invention is to perform more complex processing in a laser processing apparatus and a laser processing method that simultaneously condense and irradiate a plurality of irradiation points by phase-modulating laser light using a spatial light modulator.

[0015] Means used to solve problems

[0016] An embodiment of the present invention is a laser processing device. The laser processing device includes: a spatial light modulator that receives laser light output from a laser source, creates a hologram that modulates the phase of the laser light in each of a plurality of two-dimensionally arranged pixels, and outputs laser light phase-modulated by the hologram; a focusing optical system disposed downstream of the spatial light modulator; and a control unit that causes the spatial light modulator to create a hologram that focuses the phase-modulated laser light output from the spatial light modulator onto a plurality of irradiation points on a workpiece via the focusing optical system, and independently controls the light intensity of at least two of the plurality of irradiation points.

[0017] An embodiment of the present invention is a laser processing method. The laser processing method repeats: a control step of causing a spatial light modulator to present a hologram of the phase of modulated light in each of a plurality of pixels arranged two-dimensionally; a light modulation step of inputting laser light output from a laser source into the spatial light modulator to modulate the phase of the laser light using the hologram; and a focusing step of focusing the phase-modulated laser light. In the control step, the spatial light modulator is caused to present a hologram, wherein the phase-modulated laser light output from the spatial light modulator is focused at a plurality of irradiation points on the workpiece by the focusing step, and the light intensity of at least two of the plurality of irradiation points is independently controlled.

[0018] In the laser processing apparatus and the laser processing method described above, the control section (in the control step) independently controls the light intensity of at least two of the irradiation points included in the plurality of irradiation points with respect to each other. In this case, when there is a difference in the material of the processed object site, that is, a difference in the processing speed with respect to the same intensity of laser light, laser light can be irradiated at an appropriate light intensity at each irradiation point corresponding to each site. Therefore, according to the above-described structure, a processed object composed of two or more materials can be easily processed into a complex shape.

[0019] In addition, according to the above-described structure, in the case where the processed region is composed of a single material, the removal rate (removal amount) of the processed object can be independently controlled for each portion of the processed region by independently controlling the light intensity for each irradiation point, and thus a more complex shape can be realized.

[0020] Effects of Invention

[0021] According to the embodiment of the present application, in a laser processing apparatus and a laser processing method in which a plurality of irradiation points are simultaneously condensed and irradiated by phase-modulating laser light using a spatial light modulator, more complex processing can be performed. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a block diagram showing the structure of a laser processing apparatus 10 according to an embodiment.

[0023] Figure 2 (a) of FIG. 1 is a plan view showing phase-modulated laser light La2 irradiated on a processed object W via a condensing optical system 14, Figure 2 (b) of FIG. 1 is a view showing a part of (a) enlarged.

[0024] Figure 3 (a) to (e) of FIG. 1 are views showing examples of the planar shape of a processed region A.

[0025] Figure 4 is a block diagram showing a hardware structure example of the control section 18.

[0026] Figure 5 (a) of FIG. 2 is a sectional view showing a mode in which laser light La2 is irradiated on a processed object W including a plurality of regions Wa, Wb, Wc having different materials from each other, Figure 5 (b) of FIG. 2 is a plan view showing a light irradiation surface of the processed object W.

[0027] Figure 6 (a) of FIG. 2 is a sectional view showing a mode in which laser light La2 is irradiated on a processed object W including a plurality of regions Wa, Wb, Wc having different materials from each other, Figure 6 (b) of FIG. 2 is a plan view showing a light irradiation surface of the processed object W.

[0028] Figure 7 (a) is a cross-sectional view showing a state in which a workpiece W including a plurality of regions Wd and We having different materials is irradiated with laser light La2. Figure 7 (b) to (d) are along Figure 7 Cross-sectional views taken along line VIIb-VIIb, line VIIc-VIIc, and line VIId-VIId in (a).

[0029] Figure 8 (a) is a cross-sectional view showing the state of irradiating the workpiece W with the laser La2. Figure 8 (b) is a cross-sectional view showing a hole Ha formed in a workpiece W.

[0030] Figure 9 (a) to (c) schematically illustrate the Figure 8 FIG. 1 is a diagram showing an example of arrangement of irradiation points SP in each cross section along line IXa-IXa, line IXb-IXb, and line IXc-IXc shown in FIG. 1 . FIG.

[0031] Figure 10 (a) to (c) are diagrams schematically showing other arrangement examples of the irradiation points SP in each cross section.

[0032] Figure 11 (a) is a cross-sectional view showing the state of irradiating the workpiece W with the laser La2. Figure 11 (b) is a cross-sectional view showing a hole Hb formed in the workpiece W.

[0033] Figure 12 (a) is a cross-sectional view showing the state of irradiating the workpiece W with the laser La2. Figure 12 (b) is a cross-sectional view showing a hole Hc formed in the workpiece W.

[0034] Figure 13 (a) is a cross-sectional view showing the state of irradiating the workpiece W with the laser La2. Figure 13 (b) is a cross-sectional view showing holes Hc and Hd formed in the workpiece W.

[0035] Figure 14 (a) is a cross-sectional view showing the state of irradiating the workpiece W with the laser La2. Figure 14 (b) is a cross-sectional view showing holes Hc, Hd, and He formed in the workpiece W.

[0036] Figure 15 (a) is a diagram showing the cross-sectional shape of the through hole Hf formed when the contours of the two processed areas A have curvatures. Figure 15 (b) is a diagram showing the cross-sectional shape of a through hole Hg formed when the contour of one processed region A has a curvature.

[0037] Figure 16 (a) is a cross-sectional view showing a hole Hh formed by irradiating laser light La2, Figure 16 (b) is a plan view showing the shape of the hole Hh on one surface W1 of the workpiece W. Figure 16 (c) is a plan view showing the shape of the hole Hh on the other surface W2 of the workpiece W.

[0038] Figure 17 FIG. 1 is a diagram conceptually showing the change in shape of the processed area A in the optical axis direction of the laser light La2 for forming the hole Hh. Figure 17 (a) shows an outline of a structure for irradiating a workpiece W with laser light La2, and a cross section of the workpiece W in the optical axis direction of the laser light La2. Figure 17 (b) to (e) show the shapes of the processed regions A in the respective surfaces of the workpiece W located at different depths, and the plurality of irradiation points SP in the respective surfaces.

[0039] Figure 18 is shown with Figure 17 (b) is a diagram showing an example of a hologram corresponding to the surface, Figure 18 (a) shows Figure 17 The multiple irradiation points SP shown in (b) are Figure 18 (b) to (d) show the methods used to achieve Figure 18 An example of a hologram of a plurality of irradiation points SP shown in (a).

[0040] Figure 19 is shown with Figure 17 (c) is a diagram showing an example of a hologram corresponding to the surface, Figure 19 (a) shows Figure 17 The multiple irradiation points SP shown in (c) are Figure 19 (b) to (d) show the methods used to achieve Figure 19 An example of a hologram of a plurality of irradiation points SP shown in (a).

[0041] Figure 20 is shown with Figure 17 (d) is a diagram showing an example of a hologram corresponding to the surface, Figure 20 (a) shows Figure 17 The multiple irradiation points SP shown in (d) are Figure 20 (b) to (d) show the methods used to achieve Figure 20 An example of a hologram of a plurality of irradiation points SP shown in (a).

[0042] Figure 21 is shown with Figure 17 (e) is a diagram showing an example of a hologram corresponding to the surface, Figure 21 (a) shows Figure 17 The multiple irradiation points SP shown in (e) are Figure 21 (b) to (d) show the methods used to achieve Figure 21 An example of a hologram of a plurality of irradiation points SP shown in (a).

[0043] Figure 22 This is a diagram showing a state in which the irradiation point SP of the laser beam La2 is formed farther from the workpiece W.

[0044] Figure 23 This is a flowchart showing a laser processing method according to one embodiment.

[0045] Figure 24 This is a flowchart showing a case where the storage step S0 is performed before the control step S1.

[0046] Figure 25 This is a diagram for explaining the laser processing method described in Patent Document 1.

[0047] Figure 26 (a) to (e) are diagrams for explaining the laser processing method described in Patent Document 2.

[0048] Figure 27 This is a diagram for explaining the laser processing method described in Patent Document 2. DETAILED DESCRIPTION

[0049] Hereinafter, embodiments of the laser processing apparatus and the laser processing method will be described in detail with reference to the accompanying drawings. In the description of the drawings, identical elements are denoted by identical reference numerals, and repeated descriptions are omitted. The present invention is not limited to these examples.

[0050] Figure 1 1 is a block diagram showing the structure of a laser processing device 10 according to an embodiment. Figure 1 As shown, the laser processing apparatus 10 of this embodiment includes a laser light 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 .

[0051] The laser source 11 outputs pulsed laser light La1 having a duration of 1 picosecond or less (e.g., several femtoseconds). The wavelength of the laser light La1 output from the laser source 11 is, for example, 250 nm to 2500 nm, and in one embodiment, 1030 nm. Furthermore, the power of the laser light La1 output from the laser source 11 is, for example, 0.01 W to 1000 W, and in one embodiment, 1 W. The laser source 11 is, for example, a solid-state laser using a Yb:YAG crystal or a Yb:KGW crystal as the laser medium, or an Yb-doped fiber laser excited by a semiconductor laser.

[0052] The spatial light modulator 12 is optically coupled to the laser light source 11 and receives the laser light La1 output from the laser light source 11. The optical coupling between the spatial light modulator 12 and the laser light source 11 is, for example, spatial coupling. The spatial light modulator 12 has a plurality of pixels arranged two-dimensionally, and by presenting a hologram at these pixels, the phase of the laser light La1 is independently modulated for each pixel.

[0053] The spatial light modulator 12 has, for example, a liquid crystal structure. In this case, a single voltage, which forms a hologram, is applied to a plurality of pixel electrodes arranged two-dimensionally. 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 at each pixel varies depending on the magnitude of the electric field. Consequently, the phase of the laser light La1 can be modulated independently for each pixel.

[0054] The spatial light modulator 12 can be either a transmissive or reflective type. Furthermore, the type of spatial light modulator 12 is not limited to a liquid crystal type; various types of spatial light modulators can be used. The spatial light modulator 12 outputs laser light La2 that has been phase-modulated by the hologram.

[0055] The 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 the dichroic mirror 13 is optically coupled to the spatial light modulator 12. The modulated laser light La2 that reaches the dichroic mirror 13 from the spatial light modulator 12 is reflected (or transmitted) by the dichroic mirror 13 and directed toward the workpiece W. The dichroic mirror 13 is, for example, a short-pass dichroic mirror.

[0056] The laser light La2 passes through a focusing optical system 14 disposed after the spatial light modulator 12 (more precisely, after the dichroic mirror 13) and reaches the workpiece W. The focusing optical system 14 is, for example, a glass lens and is 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 disposed on the optical path between the dichroic mirror 13 and the workpiece W.

[0057] The driver 15 is electrically connected to each pixel electrode of the spatial light modulator 12 and supplies a drive voltage Vd to each pixel electrode to cause the spatial light modulator 12 to produce a hologram. The driver 15 includes a plurality of voltage generating circuits electrically connected to each pixel electrode. Each voltage generating circuit includes an amplifier circuit including a transistor.

[0058] The control unit 18 is electrically connected to the drive unit 15. The control unit 18 creates or reads a hologram from the storage unit and provides the two-dimensional data of the hologram to the drive unit 15. The drive unit 15 generates a drive signal, which is an analog signal based on the hologram, for each pixel. Each amplifier circuit in the drive unit 15 amplifies the drive signal to generate a drive voltage Vd.

[0059] Figure 2 (a) is a plan view showing the phase-modulated laser light La2 irradiated onto the workpiece W via the focusing optical system 14. Figure 2 (b) is to Figure 2 A portion of (a) is enlarged. Figure 2 As shown in (a), the control unit 18 generates a hologram for focusing the phase-modulated laser light La2 output from the spatial light modulator 12 on a plurality of irradiation points SP of the workpiece W through the focusing optical system 14 and causes the spatial light modulator 12 to present the hologram.

[0060] The plurality of irradiation points SP define the processing area A of the workpiece W. That is, the plurality of irradiation points SP are arranged at intervals on a closed imaginary line B, and the processing area A is defined by the imaginary line B. In addition, the control unit 18 causes the spatial light modulator 12 to sequentially present a plurality of holograms in which the positions of the irradiation points SP are changed along the imaginary line B. Thus, as shown in FIG. Figure 2 As shown in (b), each irradiation point SP moves discretely on the imaginary line B.

[0061] The planar shape of the processed region A defined by the plurality of irradiation points SP (the shape within a plane perpendicular to the optical axis of the laser light La2 ) is set in various ways depending on the purpose of processing and the like. Figure 3 : is a diagram showing an example of the planar shape of the processed area A. The processed area A may also be as Figure 3 (a) is a circle, or it can be Figure 3 (b) is an ellipse. In addition, the processed area A can also be as Figure 3 (c) is a triangle, which can also be Figure 3 (d) is a quadrilateral, which can also be Figure 3 (e) shows an arbitrary polygon.

[0062] The control unit 18 controls the light intensity (unit: W / cm2) of at least two irradiation points SP included in the plurality of irradiation points SP independently of each other. 2In other words, energy density (unit: J / cm 2 In one example, the control unit 18 independently controls the light intensity of all irradiation points 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.

[0063] For example, for materials that process faster (i.e., easier) than laser La2, the light intensity can be reduced to slow the processing speed. Conversely, for materials that process slower (i.e., more difficult) than laser La2, the light intensity can be increased to speed up the processing speed. This allows for uniform processing speeds across multiple irradiation points SP, even when materials with varying processing speeds are mixed within the illuminated surface or cross-section of the workpiece W. Alternatively, for materials significantly affected by heat, the light intensity can be reduced to minimize the area affected by the heat.

[0064] Furthermore, the control unit 18 controls at least one of the light intensity and the irradiation time (in other words, the hologram presentation time) at the plurality of irradiation points SP according to the depth positions of the plurality of irradiation points SP on the workpiece W.

[0065] For example, compared to processing the surface of the workpiece W, processing deeper into the workpiece W can reduce the processing speed because debris remaining from the previous laser La2 irradiation can obstruct the irradiation of the laser beam La2. Therefore, increasing the light intensity at multiple irradiation points SP and / or increasing the irradiation time as the workpiece W progresses deeper into the workpiece W improves processing speed and quality. Furthermore, when the workpiece W is composed of multiple layers of different materials (e.g., a semiconductor or printed wiring board), controlling the hologram change cycle or presentation time allows for laser processing tailored to the conditions of each layer.

[0066] The workpiece W to be processed in this embodiment can be made of various materials such as glass, semiconductors, metals (steel, non-ferrous metals, alloys, etc.), and composite materials (carbon fiber reinforced plastics CFRP, etc.).

[0067] Refer again Figure 1 The observation light source 16 is a laser source for irradiating the workpiece W with observation light Lb. The wavelength of the observation light Lb output from the observation light source 16 differs from the wavelengths of the laser beams La1 and La2. The wavelength of the observation light Lb is, for example, between 800 nm and 980 nm, and in one embodiment, is 808 nm. The observation light source 16 is, for example, an Al(In)GaAs-based or InGaAsP-based semiconductor laser.

[0068] The observation light source 16 is optically coupled to the other surface of the dichroic mirror 13. The observation light Lb reaching the dichroic mirror 13 from the observation light source 16 passes through the dichroic mirror 13 (or is reflected) and travels toward the workpiece W along an optical path parallel to the laser light La2, irradiating the workpiece W.

[0069] In addition, in the figure, the optical axis of the observation light Lb and the optical axis of the laser La2 are drawn in parallel, but the optical axis of the observation light Lb and the optical axis of the laser La2 may not coincide with each other. The irradiation area of ​​the observation light Lb of the workpiece W includes, for example, Figure 2 The processed area A is shown in (a).

[0070] When a portion of the observation light Lb reaches the workpiece W, it becomes reflected light Lc and is emitted 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 surface of the dichroic mirror 13 and detects the reflected light Lc via the dichroic mirror 13.

[0071] The photodetector 17 can be a two-dimensional image detector or a detector that acquires three-dimensional information. In the latter case, the photodetector 17 comprises, 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 backlight of a semiconductor laser serving as the observation light source 16), causes this portion of the observation light Lb (or the backlight) to interfere with the reflected light Lc, thereby detecting an interference light image.

[0072] The photodetector 17 is electrically connected to the control unit 18 and supplies an electric signal Sa related to the detection result to the control unit 18. An example of interferometry used in this embodiment is described in Non-Patent Document 1 (F. Mezzapesa et al., Opt. Lett. Vol. 36, pp. 822-824 (2011)).

[0073] The control unit 18 determines the processing state of each irradiation point SP based on the detection results from the photodetector 17. Furthermore, the control unit 18 controls the hologram presented by the spatial light modulator 12 according to the processing state. Hologram control herein refers to, for example, controlling the presentation time of the hologram and changing the hologram to an appropriate one.

[0074] Figure 4 1 is a block diagram showing an example of the hardware configuration of the control unit 18. Figure 4As shown, the control unit 18 is configured as a computer including hardware such as a CPU 181, RAM 182, ROM 183, input device 184, digital / analog converter 185, auxiliary storage device 186, and display output device 187. The control unit 18 realizes the above-described functions by operating these components according to a program pre-stored in the auxiliary storage device 186.

[0075] Hereinafter, a processing example of the laser processing apparatus 10 according to the present embodiment will be described. Figure 5 (a) and Figure 6 (a) is a cross-sectional view showing the state of irradiating the workpiece W including multiple regions Wa, Wb, and Wc of different materials with laser La2, and shows a cross section along the optical axis of the laser La2 (in other words, along the thickness direction of the workpiece W). Figure 5 (b) and Figure 6 (b) is a plan view showing the light-irradiated surface of the workpiece W.

[0076] In these examples, regions Wa, Wb, and Wc are arranged in a direction intersecting the optical axis of laser light La2 (the thickness direction of the workpiece W), with their boundaries exposed on the irradiated surface. For laser light La2 of the same intensity, the processing speeds of the materials in each region Wa, Wb, and Wc differ. Specifically, for laser light La2 of the same intensity, region Wa has the slowest processing speed, while region Wc has the fastest processing speed.

[0077] exist Figure 5 In the example shown, three mutually independent processed areas A are set for each of the areas Wa, Wb, and Wc. Furthermore, a plurality of irradiation points SP are formed in the area Wa to define one processed area A, a plurality of irradiation points SP are formed in the area Wb to define another processed area A, and a plurality of irradiation points SP are formed in the area Wc to define yet another processed area A.

[0078] exist Figure 6 In the example shown, a processed region A spanning regions Wa and Wb, and another processed region A spanning regions Wb and Wc are set. Furthermore, a plurality of irradiation points SP defining a portion of one processed region A are formed in region Wa, a plurality of irradiation points SP defining the remaining portion of one processed region A and a plurality of irradiation points SP defining a portion of another processed region A are formed in region Wb, and a plurality of irradiation points SP defining the remaining portion of another processed region A are formed in region Wc.

[0079] In this case, if Figure 5 (b) and Figure 6As shown in (b), the control unit 18 controls the hologram displayed on the spatial light modulator 12 in such a way that the light intensity of the irradiation point SP formed in the area Wa is the maximum and the light intensity of the irradiation point SP formed in the area Wc is the minimum. Figure 18 In addition, Figure 5 (b) and Figure 6 In (b), the light intensity of each irradiation point SP is represented by the depth of the color. The darker the color, the greater the light intensity, and the lighter the color, the smaller the light intensity.

[0080] This allows the processing speeds at the irradiation points SP in the regions Wa, Wb, and Wc to be close to each other, making the processing depth uniform. Ideally, the relative relationship of the light intensities at the irradiation points SP is adjusted so that the processing speeds at the irradiation points SP are equal.

[0081] 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 in the figure detect the material at each irradiation point SP. Since the reflectivity of the observation light Lb depends on the material, the material at each irradiation point SP can be determined based on the intensity ratio between the observation light Lb and the reflected light Lc. This allows the boundaries of the areas Wa, Wb, and Wc to be detected.

[0082] Furthermore, the spatial light modulator 12 can be caused to generate a hologram that realizes the light intensities of the irradiation points SP corresponding to the respective regions Wa, Wb, and Wc. In other words, in this example, the control unit 18 can generate a hologram for independently setting the light intensities of the irradiation points SP based on the detection results of the light detector 17.

[0083] Alternatively, data on the light intensity of each irradiation point SP corresponding to the distribution of the regions Wa, Wb, and Wc may be stored in advance in a storage unit (eg, Figure 4 In this case, the control unit 18 can control the light intensity of each irradiation point SP based on the data.

[0084] Figure 7 (a) is a cross-sectional view showing a state where a workpiece W including a plurality of regions Wd and We having different materials is irradiated with laser light La2, and shows a cross section along the optical axis of laser light 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 views taken along lines VIIb-VIIb, VIIc-VIIc, and VIId-VIId in (a) show cross-sectional views perpendicular to the optical axis of the laser light La2.

[0085] In this example, regions Wd and We are aligned along the optical axis of laser light La2, and their boundary is tilted relative to an imaginary plane perpendicular to the optical axis of laser light La2. With respect to laser light La2 of the same intensity, the processing speed of the material in each region Wd and We differs. Specifically, with respect to laser light La2 of the same intensity, the processing speed of region Wd is slower than that of region We.

[0086] In this example, a processing area A is set for the workpiece W, and a plurality of irradiation points SP defining the processing area A are formed on the workpiece W. Figure 7 In (b), (c), and (d), the light intensity of each irradiation point SP is also expressed by the depth of the color. The darker the color, the greater the light intensity, and the lighter the color, the smaller the light intensity.

[0087] First, in Figure 7 At the timing shown in (b), the processing speed of each irradiation point SP in the area Wd becomes an arbitrary speed, and the control unit 18 controls the hologram presented on the spatial light modulator 12. When the processing progresses to a certain depth, as shown in FIG. Figure 7 As shown in (c), the processed area A spans the area Wd and 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 light intensity of the irradiation point SP located in the area We becomes smaller than the light intensity of the irradiation point SP located in the area Wd.

[0088] As the processing progresses, the proportion of We in the processed area A gradually increases, and finally Figure 7 As shown in (d), the processed area A includes only the area We. At this time, the control unit 18 controls the hologram presented on the spatial light modulator 12 so that the processing speed at each irradiation point SP in the area We becomes an arbitrary speed.

[0089] In this example, the control unit 18 controls the hologram so that the light intensity of the irradiation point SP formed in the region Wd becomes greater than the light intensity of the irradiation point SP formed in the region We. Figure 7 (c)) can make the processing speeds of the irradiation points SP in each area Wd and We close to each other, making the processing depth uniform. Ideally, the light intensity at each irradiation point SP is adjusted so that the processing speed at each irradiation point SP becomes uniform in the depth direction.

[0090] 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 here detect changes in the material at each irradiation point SP. Since the reflectivity of the observation light Lb depends on the material, the intensity ratio between the observation light Lb and the reflected light Lc changes when the material at each irradiation point SP changes. Therefore, changes in the material from area Wd to area We can be detected.

[0091] Furthermore, at the timing of this change, the spatial light modulator 12 can be caused to present a hologram that changes the light intensity at the irradiation point SP as it changes from the region Wd to the region We. In other words, in this example, the timing of changing the hologram for changing the light intensity at each irradiation point SP can be determined based on the detection results of the light detector 17.

[0092] Alternatively, data on the light intensity at each irradiation point SP corresponding to the material distribution of the workpiece W may be stored in advance in a storage unit (for example, Figure 4 In this case, the control unit 18 can control the light intensity of each irradiation point SP based on the data.

[0093] Figure 8 (a) is a cross-sectional view showing a state where the workpiece W is irradiated with the laser light La2, and shows a cross section along the optical axis of the laser light La2. Figure 8 (b) is a cross-sectional view showing a hole Ha formed in the workpiece W. Figure 8 In the example shown, the size of the processed area A changes continuously along the optical axis of the laser light La2, from the light-irradiated surface W1 of the workpiece W to the opposite surface W2. This continuous change in the size of the processed area A means that the contour of the processed area A does not exhibit any step differences in a cross-section taken along the optical axis of the laser light La2.

[0094] In this example, the holograms are switched sequentially as processing progresses in the direction of the optical axis of the laser light La2 (the depth direction of the workpiece W). Each hologram is a superposition of a hologram for achieving the size and shape of the processed area A within a plane intersecting the optical axis of the laser light La2 and a hologram for the position of that plane in the direction of the optical axis.

[0095] Figure 9 (a), (b), and (c) schematically illustrate the Figure 8 1. (a) shows an example of the arrangement of the irradiation points SP in each cross section of line IXa-IXa, line IXb-IXb, and line IXc-IXc. In this example, the shape of the processed area A in the cross section perpendicular to the optical axis direction of the laser La2 is set to a circle.

[0096] in addition, Figure 10(a), (b), and (c) schematically illustrate other configuration examples of the irradiation points SP in each cross section. In this example, the shape of the processed region A in the cross section perpendicular to the optical axis direction of the laser light La2 is set to an arbitrary complex polygon.

[0097] Figure 9 and Figure 10 The irradiation points SP shown are delineated Figure 8 The processed area A shown in (a) is not limited to the shape of the processed area A in the cross section perpendicular to the optical axis direction of the laser La2. Figure 9 and Figure 10 Examples of the present invention may be various other shapes.

[0098] 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 cross section and the IXb-IXb cross section, which are separated from each other in the optical axis direction, different from each other. In this case, one of the IXa-IXa cross section and the IXb-IXb cross section corresponds to the first surface of this embodiment, and the other corresponds to the second surface of this embodiment.

[0099] Furthermore, if another observation angle is used, the control unit 18 makes the sizes of the processed areas A of the IXb-IXb cross section and the IXc-IXc cross section, which are separated from each other in the optical axis direction, different from each other. In this case, one of the IXb-IXb cross section and the IXc-IXc cross section corresponds to the first surface of this embodiment, and the other corresponds to the second surface of this embodiment.

[0100] In this example, the control unit 18 also causes the spatial light modulator 12 to sequentially present an imaginary line B (see FIG. 1 ) defining the processed area A in each cross section. Figure 2 (b)) A plurality of holograms in which the position of each irradiation point SP is changed. Thus, each irradiation point SP moves discretely on the contour line of the processed area A.

[0101] The control unit 18 can also determine the processing status of each irradiation point SP based on the detection results of the light detector 17, and control the presentation time of the hologram in each cross section 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 the processing).

[0102] When the workpiece W is light-transmissive to the laser light La2, as shown in FIG. Figure 8As shown, an inverted tapered (tapered relative to the surface W2) processed area A may be set on the light-irradiated surface W1 of the workpiece W. In other words, the area of ​​the processed area A in one of the cross sections IXa-IXa and IXb-IXb (or the cross section IXb-IXb and IXc-IXc) farther from the light-irradiated surface W1 of the workpiece W may be larger than the area of ​​the processed area A in the other cross section.

[0103] In this case, the control unit 18 causes the spatial light modulator 12 to produce a hologram that focuses the laser light La2 on each irradiation point SP, thereby cutting off the outline of the processed area A and causing the processed area A to fall downward from the workpiece W. Figure 8 As shown in (b) of FIG. 1 , a hole Ha is formed in the workpiece W as a through hole having an inverted tapered shape relative to the light irradiation surface W1 .

[0104] If the workpiece W is made of a material such as glass that is light-transmissive to the laser light La2, processing can be performed sequentially from the surface W2 of the workpiece W opposite the light-irradiated surface W1 toward the light-irradiated surface W1. This processing is achieved by ensuring that the light intensity exceeds the processing threshold only at the focal point of the laser light La2, while reducing the light intensity to below the threshold in other areas of the workpiece W (the area between the light-irradiated surface W1 and the focal point).

[0105] In this case, since the laser processing can be performed while the remaining objects (fragments or fragments) generated by the laser processing are dropped downward, the degree to which the irradiation of the laser light La2 is blocked by the remaining objects is reduced.

[0106] Figure 11 (a) is a cross-sectional view showing a state where the workpiece W is irradiated with the laser light La2, and shows a cross section along the optical axis of the laser light La2. Figure 11 (b) is a cross-sectional view showing a hole Hb formed in the workpiece W. Figure 11 In the example shown, Figure 8 Similarly to the example shown, the size of the processed area A in the cross section perpendicular to the optical axis of the laser La2 changes continuously in the optical axis direction of the laser La2 from the light irradiated surface W1 of the workpiece W to the opposite surface W2.

[0107] Specifically, the size of the processed area A in the cross section gradually increases as it moves away from the light irradiation surface W1. Figure 11 In the example shown, the contour of the processed area A in the cross section along the optical axis of the laser La2 becomes a shape having an inwardly convex curvature (e.g., an arc shape), rather than a Figure 8 straight line.

[0108] In this case, the control unit 18 causes the spatial light modulator 12 to produce a hologram that focuses the laser light La2 on each irradiation point SP, thereby cutting off the outline of the processed area A and causing the processed area A to fall downward from the workpiece W. Figure 11 As shown in (b) of FIG. 1 , a hole Hb is formed in the workpiece W as a through hole having an inversely tapered shape relative to the light irradiation surface W1 .

[0109] Figures 12 to 14 (a) is a cross-sectional view showing a state where the workpiece W is irradiated with the laser light La2, and shows a cross section along the optical axis of the laser light La2. Figures 12 to 14 (b) is a cross-sectional view showing holes Hc, Hd, and He formed in the workpiece W.

[0110] In this example, first, Figure 12 As shown in (a), a tapered processing area A is set from the approximate center of the workpiece W in the optical axis direction of the laser La2 to a surface W3. And the laser La2 is irradiated from another surface W4 on the opposite side of the surface W3. Figure 8 In the same way as shown in the example, the outline of the processed area A is cut off to form Figure 12 The hole Hc shown in (b) is a tapered (mortar-shaped) recess extending from the approximate center of the workpiece W to one surface W3.

[0111] Then, if Figure 13 As shown in (a), the workpiece W is turned upside down and a tapered processing area A is set from the approximate center of the workpiece W in the optical axis direction of the laser La2 to the other surface W4. And, the laser La2 is irradiated from one surface W3, and the laser beam is irradiated from the other surface W4. Figure 8 In the same way as shown in the example, the outline of the processed area A is cut off to form Figure 13 The hole Hd shown in (b) is a tapered (mortar-shaped) recess extending from the approximate center of the workpiece W to the other surface W4.

[0112] Finally, if Figure 14 As shown in (a), the connection hole Hc and the hole Hd are set to form another processing area A. Then, the laser La2 is irradiated from the surface W3 or W4. Figure 8 In the same way as shown in the example, the outline of the processed area A is cut off to form Figure 14 In this way, a hole is formed that passes through the one surface W3 and the other surface W4 of the workpiece W.

[0113] In the above example, the contours of the processed regions A in the cross section along the optical axis of the laser light La2 are linear, but at least one of them may have a curvature. Figure 15(a) shows the cross-sectional shape of a through hole Hf formed when two processed areas A have curvature. The through hole Hf is formed by connecting a hole Hfa extending from the approximate center of the workpiece W to the surface W3 and a hole Hfb extending from the approximate center of the workpiece W to the surface W4.

[0114] The size of hole Hfa, as measured in a cross section perpendicular to the optical axis of laser light La2, gradually increases as it approaches surface W3 from the approximate center of the workpiece W. The size of hole Hfb, as measured in a cross section perpendicular to the optical axis of laser light La2, gradually increases as it approaches surface W4 from the approximate center of the workpiece W. Furthermore, the side surfaces of these holes Hfa and Hfb have an inwardly convex curvature in a cross section along the thickness direction of the workpiece W.

[0115] in addition, Figure 15 (b) shows the cross-sectional shape of a through hole Hg formed when the contour of a processed area A has curvature. The through hole Hg is formed by connecting a hole Hga extending from the approximate center of the workpiece W to the surface W3 and a hole Hgb extending from the approximate center of the workpiece W to the surface W4.

[0116] The size of the hole Hga in the cross section perpendicular to the optical axis of the laser La2 gradually increases as it approaches the surface W3 from the approximate center of the workpiece W. In addition, the side surface of the hole Hga has a curvature that is convex inward in the cross section along the thickness direction of the workpiece W. Figure 12 The hole Hc and Figure 13 The hole Hd shown similarly has a tapered shape (mortar shape) when viewed from the surface W4.

[0117] Figure 16 (a) is a cross-sectional view showing a hole Hh formed by irradiation with the laser beam La2, and shows a cross section along the thickness direction of the workpiece W. Figure 16 (b) is a plan view showing the shape of the hole Hh on the light irradiated surface W1 of the workpiece W, Figure 16 (c) is a plan view showing the shape of the hole Hh on the surface W2 opposite to the light irradiation surface W1 of the workpiece W.

[0118] In this example, the shape of the hole Hh on the light-irradiated surface W1 (the first surface intersecting the optical axis of the laser beam La2) differs from the shape of the hole Hh on the surface W2 opposite to the light-irradiated surface W1 (the second surface separated from the first surface in the optical axis direction). In the illustrated example, the hole Hh on the light-irradiated surface W1 is circular, while the hole Hh on the opposite surface W2 is an equilateral triangle.

[0119] Such holes Hh can be appropriately formed by varying the shapes of the processed areas A defined by a plurality of irradiation points on each of the light irradiation surfaces W1 and W2 using the control unit 18. In one example, the cross-sectional shape of the hole Hh perpendicular to the thickness direction of the workpiece W continuously changes along the thickness direction of the workpiece W.

[0120] Figure 17 It is a conceptual illustration to form Figure 16 FIG. 1 shows a diagram illustrating a change in the shape of the processed region A in the optical axis direction of the laser light La2 for the hole Hh. Figure 17 (a) shows an outline of a structure for irradiating the workpiece W with the laser light La2 and a cross section of the workpiece W in the optical axis direction of the laser light La2. Figure 17 (b), (c), (d), and (e) show the shapes of the processed regions A on the respective surfaces at different depths in the workpiece W, and the plurality of irradiation points SP on the respective surfaces.

[0121] like Figure 17 As shown in (b), the shape of the processed area A on the light irradiated surface W1 is circular, as shown in FIG. Figure 17 As shown in (c) to (e) of FIG. , the shape of the processed area A gradually shifts from a circle to a triangle as the area moves away from the light-irradiated surface W1 in the optical axis direction. Ultimately, the shape of the processed area A on surface W2 becomes a triangle. Furthermore, as described above, if the workpiece W is light-transmitting, processing can be performed from the surface W2 toward the light-irradiated surface W1.

[0122] Figures 18 to 21 is shown with Figure 17 Figures showing examples of holograms corresponding to the respective surfaces shown in (b) to (e). Figures 18 to 21 (a) shows Figure 17 Multiple irradiation points SP shown in (b) to (e). Figures 18 to 21 (b), (c), and (d) respectively show examples of holograms for realizing the plurality of irradiation points SP shown in (a). Figures 18 to 21 In (b), (c), and (d), the phase size is represented by the depth of the color. 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).

[0123] In addition, Figures 18 to 21 In each figure, (b), (c), and (d) show the contour lines ( Figure 2As shown by the arrows in the figure, the control unit 18 causes the holograms (b), (c), and (d) to be periodically and repeatedly presented to the spatial light modulator 12, thereby performing processing while moving the position of each irradiation point SP along the contour of the processed area A.

[0124] exist Figures 7 to 17 In each of the processing examples shown, it is necessary to change the hologram in the middle of the laser processing. In addition, when changing the hologram, it is necessary to use a memory unit (for example, Figure 4 The ROM 183 or the auxiliary storage device 186 shown in the figure calls out the hologram to be presented subsequently, or generates the time of the hologram to be presented subsequently by calculation based on the detection result of the light detector 17.

[0125] During the period from erasing a certain hologram to presenting another hologram, the control unit 18 causes the spatial light modulator 12 to present a hologram in which the light intensity of the laser light La2 is set to be less than the processing threshold value at any part of the workpiece W. For example, Figure 22 As shown, the control unit 18 may cause the spatial light modulator 12 to produce a hologram such that the irradiation point SP of the laser light La2 is formed farther from the workpiece W. This achieves an effect equivalent to turning off the laser light source 11.

[0126] In addition, Figures 8 to 17 In each processing example shown, in each surface arranged in the optical axis direction of the laser La2, Figures 5 to 7 As in the processing examples shown, the control unit 18 may independently control the light intensity of the plurality of irradiation points SP for each irradiation point SP. Alternatively, the control unit 18 may independently control the light intensity of the irradiation points SP on each surface aligned in the optical axis direction.

[0127] For example, in Figures 8 to 10 In the example shown, the light intensity at the irradiation point SP in the cross sections IXa-IXa, IXb-IXb, and IXc-IXc can be independently set for each cross section according to the material (or processing speed) of each cross section. Furthermore, the irradiation time for each cross section can also be independently set.

[0128] Figure 23 Flowchart showing the laser processing method of this embodiment. The laser processing method can be performed using the laser processing device 10 described above. Figure 23As shown, first, as a control step S1, the spatial light modulator 12 is caused to generate a hologram representing the phase of modulated light in each of a plurality of pixels arranged two-dimensionally. Next, as a light modulation step S2, laser light La1 output from the laser source 11 is input to the spatial light modulator 12, where the phase of the laser light La1 is modulated using the hologram. Furthermore, as a focusing step S3, the phase-modulated laser light La2 is focused using the focusing optical system 14.

[0129] In the previous control step S1, the spatial light modulator 12 is caused to produce a hologram in which the phase-modulated laser light La2 is focused at multiple irradiation points SP on the workpiece W in the focusing step S3. This forms multiple irradiation points SP on the workpiece W, and processing (melting, cracking, cutting, etc.) of the workpiece W is performed at each irradiation point SP. Furthermore, in the light detection step S4, observation light Lb having a wavelength different from that of the laser light La2 is irradiated onto the workpiece W, and the observation light (reflected light Lc) reflected from the workpiece W is detected.

[0130] Afterwards, steps S1 to S4 are repeated while changing the hologram. Figure 2 As shown, the spatial light modulator 12 is caused to sequentially present a plurality of holograms in which the position of each irradiation point SP is changed along an imaginary line B defining the processed area A. Furthermore, if the difference between the set target value of the light intensity at the irradiation point SP and the detection result of the observation light is greater than the target error (step S5: NO), the hologram may be corrected (step S6).

[0131] like Figures 5 to 7 As shown, in the control step S1, the light intensity of the plurality of irradiation points SP is controlled independently for each irradiation point SP. Figures 8 to 17 As shown, in the control step S1, the shape of the processed area A defined by the plurality of irradiation points SP is made different for each of the plurality of surfaces intersecting the optical axis of the laser light La2. Alternatively, in the control step S1, the light intensity of the plurality of irradiation points SP is independently controlled for each irradiation point SP, and the shape of the processed area A defined by the plurality of irradiation points SP is made different for each of the plurality of surfaces intersecting the optical axis of the laser light La2.

[0132] When the light intensity is controlled independently for each irradiation point SP, in the control step S1 , the material change at each irradiation point SP is detected based on the detection result of the previous light detection step S4 , and the light intensity at each irradiation point SP is changed according to the material change.

[0133] Or, as Figure 24As shown, the 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 is pre-stored in the storage unit (for example, Figure 4 ROM 183 or auxiliary storage device 186 shown in FIG. Then, in control step S1, the light intensity at each irradiation point SP is controlled based on this data. Furthermore, if the difference between the set target value of the light intensity at the irradiation point SP and the detection result of the observation light is greater than the target error (step S5: NO), the hologram may be corrected (step S6).

[0134] In addition, when the shape of the processed area A is made different for each of the multiple surfaces intersecting the optical axis of the laser La2, it is also possible to Figures 8 to 15 As shown, the shape of the processed area A is continuously changed in the optical axis direction of the laser La2. In the case where the workpiece W is light-transmissive to the laser La2, it can also be changed as shown in FIG. Figures 8 to 15 As shown, the area of ​​the processed region A on the surface farther from the light irradiation surface W1 of the workpiece W is made larger than the area of ​​the processed region A on the surface closer to the light irradiation surface W1.

[0135] The processing state at each irradiation point SP can be determined based on the detection result in the light detection step S4, and the hologram presentation time for each surface can be controlled according to the processing state. The light intensity of multiple irradiation points SP can also be controlled independently for each surface.

[0136] Furthermore, when changing the hologram in the control step S1, the spatial light modulator 12 is caused to present a hologram in which the light intensity of the laser light La2 is set to be less than the processing threshold at any part of the workpiece W during the period from erasing a certain hologram to presenting another hologram.

[0137] The effects obtained by the laser processing apparatus 10 and the laser processing method according to the present embodiment described above will be described.

[0138] In the laser processing apparatus 10 and laser processing method of this embodiment, the control unit 18 (or in control step S1) independently controls the light intensity of at least two irradiation points SP included in the plurality of irradiation points SP. In this case, if the materials of parts of the workpiece W differ, that is, if the processing speed for laser light La2 of the same intensity differs, laser light La2 can be irradiated at an appropriate light intensity at each irradiation point SP corresponding to each part. This makes it easy to process workpieces W composed of two or more materials into complex shapes.

[0139] Furthermore, according to this embodiment, it is possible to adjust the light intensity at each irradiation point SP, turn each irradiation point SP on and off, and move each irradiation point SP along the imaginary line B without using any mechanical unit. Therefore, the device structure of the laser processing device 10 can be greatly simplified, and processing can be performed at high speed and high precision.

[0140] As in the present embodiment, the laser processing apparatus 10 may include an observation light source 16 for irradiating the workpiece W with observation light Lb, and a light detector 17 for detecting the observation light reflected by the workpiece W, i.e., reflected light Lc. Furthermore, the laser processing method may further include a light detection step S4 of irradiating the workpiece W with observation light Lb and detecting reflected light Lc from the workpiece W.

[0141] Furthermore, the control unit 18 (in control step S1) may determine the processing status at each irradiation point SP based on the detection results of the light detector 17 and control the hologram presentation time for each surface accordingly. Alternatively, the control unit 18 (in control step S1) may detect changes in the material at each irradiation point SP based on the detection results of the light detector 17 (light detection step S4) and adjust the light intensity at at least two irradiation points SP in response to the material changes. In these cases, processing accuracy can be further improved.

[0142] As in the present embodiment, the laser processing apparatus 10 may include a storage unit that pre-stores data related to the light intensity at each irradiation point SP corresponding to the material distribution of the workpiece W, and the control unit 18 may control the light intensity at each irradiation point SP based on this data. Alternatively, the laser processing method may include, before the control step S1, a storage step S0 of pre-stored data related to the light intensity at each irradiation point SP corresponding to the material distribution of the workpiece W, and, in the control step S1, controlling the light intensity at each irradiation point SP based on this data. In these cases, the required light intensity at each irradiation point SP can be quickly obtained, thereby shortening the time required to change a hologram.

[0143] As shown in this embodiment, the control unit 18 (in control step S1) can also make at least one of the shape and size of the processed area A different in multiple surfaces arranged in the optical axis direction of the laser light La2. In this way, by changing the shape and / or size of the processed area A for each of the multiple surfaces separated in the optical axis direction, more complex processing can be performed than before, such as freely setting the shape of a cross section perpendicular to the optical axis direction.

[0144] As in the present embodiment, the control unit 18 (in the control step S1) may cause the spatial light modulator 12 to sequentially present a plurality of holograms in which the positions of the irradiation points SP are changed along the imaginary line B defining the processed area A for each of the plurality of surfaces arranged in the optical axis direction. In this case, sufficient light intensity is given to each irradiation point SP, and a single hologram is used. Figure 1 Compared with the case of the secondary irradiation laser La2 , the output power required for the laser light source 11 can be reduced, which can contribute to the miniaturization of the laser light source 11 .

[0145] As in this embodiment, when a hologram is to be changed, the control unit 18 (in control step S1) may cause the spatial light modulator 12 to present a hologram in which the light intensity of the laser light La2 is set to be less than the processing threshold at any location on the workpiece W, during the period between erasing a certain hologram and presenting a different hologram. In this case, compared to a case where the laser light La2 is blocked by a mechanical mechanism such as a shutter, the mechanical shutter itself or the high-voltage device required to operate the mechanical shutter are not required. Therefore, the structure of the laser processing apparatus 10 can be simplified, contributing to the miniaturization and cost reduction of the laser processing apparatus 10.

[0146] As in the present embodiment, the workpiece W may be optically transparent to the phase-modulated laser light La2, and the area of ​​the processed region A on a surface farther from the light-irradiated surface W1 of the workpiece W may be larger than the area of ​​the processed region A on a surface closer to the light-irradiated surface W1. In this case, complex processing such as forming a hole with an inverted tapered shape whose diameter increases as it moves away from the light-irradiated surface W1 of the workpiece W can be easily performed.

[0147] As in this embodiment, the control unit 18 (in control step S1) may also continuously change at least one of the shape and size of the processed area A in the direction of the optical axis of the laser light La2. In this case, it is possible to easily process a hole, for example, in which the cross-sectional shape perpendicular to the optical axis smoothly deforms in the direction of the optical axis.

[0148] As in this embodiment, the control unit 18 (in control step S1) may independently control the light intensity at the irradiation point SP on at least two surfaces for each surface. In this case, if the materials constituting each surface differ, that is, if the processing speed for laser light La2 of the same intensity differs, laser light La2 can be irradiated at an appropriate light intensity based on the material of each surface.

[0149] An example of a conventional laser processing method will be described. Figure 25 This is a diagram for explaining the laser processing method described in Patent Document 1. This laser processing method is a method of processing a workpiece (processed object) 110 having a processed surface 112 by laser ablation, thereby forming a three-dimensional geometric shape 114 in the workpiece 110 .

[0150] Figure 25 Three 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 irradiated areas 122 and non-irradiated areas 124 at the processing surface 112. In the irradiated area 122, the light intensity is above the ablation threshold. In the non-irradiated area 124, the light intensity is below the dissolution threshold of the material of the workpiece 110.

[0151] Each beam profile 116, 118, 120 differs from one another in terms of 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 a partial notch in workpiece 110, beam profiles 116, 118, 120 may have differing geometries. Consequently, a stepped geometry is created in workpiece 110.

[0152] However, the method described in Patent Document 1 requires a laser source with extremely high output power to achieve a laser beam above the ablation threshold throughout the entire area, since the laser beam is irradiated simultaneously over a large area. This results in a larger laser source. Furthermore, since the beam profile diameter decreases as processing progresses, there are limitations on the shapes that can be formed. Furthermore, if the workpiece 110 contains a mixture of various materials with varying processing speeds, it is difficult to tailor the light intensity and irradiation time to the properties of each material.

[0153] With regard to these problems, according to the laser processing apparatus 10 and the laser processing method of this embodiment, since the laser light La2 is focused on a plurality of irradiation points SP for processing, the output power of the laser source 11 can be relatively low, which can contribute to the miniaturization of the laser source 11. In addition, it is also easy to perform, for example, Figure 8 The inverted cone hole Ha shown, or Figure 16 Processing of complex shapes such as the hole Hh shown.

[0154] Furthermore, since the light intensity and irradiation time are independently controlled for each irradiation point SP, even when a variety of materials are mixed in the processing area, the light intensity and irradiation time can be easily adjusted according to the properties of each material. Furthermore, optical components such as a λ / 2 plate or a polarizing beam splitter for adjusting light intensity are no longer required, further simplifying the structure of the laser processing device.

[0155] Figure 26 and Figure 27 This figure is used to illustrate the laser processing method described in Patent Document 2. In this laser processing method, a plurality of image reconstruction hologram data are prepared and laser processing is performed. Specifically, Figure 26As shown in (a), the processing surface 200 is divided into a plurality of units 201, one irradiation point 202 corresponds to one unit 201, and whether or not to form an irradiation point 202 for each unit 201 is freely selectable.

[0156] The position shift hologram data is overlapped with the image reconstruction hologram data. And, by changing the position shift hologram data, the processed surface 200 is processed to form Figure 26 (b) to (e) show the discrete point images, thus obtaining Figure 27 The complex shape of the machining shape 203 is shown.

[0157] However, in the method described in Patent Document 2, since the light intensity of each irradiation point 202 is not individually controlled, when the processed surface 200 is mixed with a variety of materials with different processing speeds, it is difficult to set the light intensity and irradiation time according to the properties of each material.

[0158] In contrast, according to the laser processing device 10 and the laser processing method of this embodiment, since the light intensity and irradiation time are independently controlled for each irradiation point SP, even when a variety of materials are mixed in the processed area, the light intensity and irradiation time can be easily set according to the properties of each material.

[0159] The laser processing apparatus and laser processing method are not limited to the above-described embodiments and configuration examples, and various other variations are possible. For example, in the above-described embodiment, it was described that, when the processing area A comprises multiple materials, by independently controlling the light intensity at each irradiation point SP, processing with light intensities corresponding to the properties of each material is possible. Without being limited to this example, even when the processing 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 portion of the processing area A, thereby enabling the realization of more complex shapes.

[0160] In addition, in the above embodiment, the case where the light intensity of the plurality of irradiation points SP is independently controlled is exemplified. However, it is not necessary to independently control all of the irradiation points SP. Alternatively, the light intensity of at least two of the plurality of irradiation points SP may be independently controlled. In this case, the effects of the above embodiment can also be achieved.

[0161] The laser processing apparatus of the above embodiment is configured to include: a spatial light modulator that inputs laser light output from a laser source, presents a hologram that modulates a phase of the laser light in each of a plurality of pixels arranged two-dimensionally, and outputs the laser light phase-modulated by the hologram; a condensing optical system provided at a rear stage of the spatial light modulator; and a control section that causes the spatial light modulator to present a hologram that condenses the laser light phase-modulated by the spatial light modulator by the condensing optical system to a plurality of irradiation points of an object to be processed, and controls light intensities of at least two irradiation points included in the plurality of irradiation points independently of each other.

[0162] The laser processing method of the above embodiment is configured to repeatedly perform: a control step of causing the spatial light modulator to present a hologram that modulates a phase of light in each of a plurality of pixels arranged two-dimensionally; a light modulation step of inputting laser light output from a laser source to the spatial light modulator and performing phase modulation of the laser light by the hologram; and a condensing step of condensing the laser light phase-modulated, in the control step, the spatial light modulator is caused to present a hologram that condenses the laser light phase-modulated by the spatial light modulator by the condensing step to a plurality of irradiation points of an object to be processed, and light intensities of at least two irradiation points included in the plurality of irradiation points are controlled independently of each other.

[0163] The laser processing apparatus of the above embodiment can also be configured to further include: an observation light source that irradiates observation light to the object to be processed; and a light detector that detects the observation light reflected by the object to be processed, and the control section detects a change in a material at each irradiation point based on a detection result of the light detector and changes the light intensity of each irradiation point according to the change in the material.

[0164] The laser processing method of the above embodiment can also be configured to further include: a light detection step of irradiating observation light to the object to be processed and detecting the observation light reflected by the object to be processed, and in the control step, a change in a material at each irradiation point is detected based on a detection result of the light detection step and the light intensity of each irradiation point is changed according to the change in the material.

[0165] According to this configuration, the processing accuracy can be further improved.

[0166] The laser processing apparatus of the above embodiment can also be configured to further include: a storage section that stores, in advance, data related to the light intensity of each irradiation point corresponding to a material distribution of the object to be processed, and the control section controls the light intensity of each irradiation point based on the data.

[0167] The laser processing method of the above embodiment can also be configured to further include, before the control step, a storage step of storing, in advance, data related to the light intensity of each irradiation point corresponding to a material distribution of the object to be processed, and in the control step, the light intensity of each irradiation point is controlled based on the data.

[0168] According to this configuration, the required light intensity at each irradiation point can be quickly obtained, and thus the change time of the hologram can be shortened.

[0169] In the laser processing apparatus described above, the control section can make at least one of the shape and size of the two processed regions different from each other, the two processed regions being a processed region defined by the plurality of irradiation points in a first plane intersecting an optical axis of the phase-modulated laser irradiated to the processed object, 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 in the direction of the optical axis.

[0170] In the laser processing method described above, in the control step, at least one of the shape and size of the two processed regions can be made different from each other, the two processed regions being a processed region defined by the plurality of irradiation points in a first plane intersecting an optical axis of the phase-modulated laser irradiated to the processed object, 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 in the direction of the optical axis.

[0171] Thus, by changing the shape and / or size of the processed region for each of the plurality of planes separated in the direction of the optical axis, a more complex processing than the prior art, such as freely setting the cross-sectional shape perpendicular to the direction of the optical axis, can be performed.

[0172] In the laser processing apparatus described above, the control section can cause the spatial light modulator to sequentially present a plurality of holograms that change the position of each irradiation point along an imaginary line that defines the processed region defined by the plurality of irradiation points.

[0173] In the laser processing method described above, in the control step, the spatial light modulator can be caused to sequentially present a plurality of holograms that change the position of each irradiation point along an imaginary line that defines the processed region defined by the plurality of irradiation points.

[0174] According to this configuration, the required light intensity at each irradiation point can be quickly obtained, and thus the change time of the hologram can be shortened. Figure 1 Compared to the case where the laser source is irradiated with the laser light for each irradiation point, the output power required for the laser source can be reduced, and the miniaturization of the laser source can be facilitated.

[0175] In the laser processing apparatus described above, the control section can cause the spatial light modulator to present, during a period from erasing a certain hologram to presenting another hologram, a hologram that sets the light intensity of the laser light to be less than the processing threshold at any part of the processed object, when changing the hologram.

[0176] In the above-mentioned laser processing method, it can also be constructed so that in the control step, when changing the hologram, during the period from eliminating a certain hologram to presenting another hologram, the spatial light modulator is caused to present: the light intensity of the laser is set to a hologram that is less than the processing threshold at any part of the workpiece.

[0177] According to this configuration, the structure of the laser processing apparatus can be simplified compared to a case where the laser light is blocked by a mechanical mechanism such as a shutter.

[0178] [Industrial Applicability]

[0179] The present invention can be used as a laser processing apparatus and a laser processing method that can perform more complex processing in a structure in which a spatial light modulator is used to modulate the phase of laser light and simultaneously condense and irradiate a plurality of irradiation points.

[0180] Explanation of symbols

[0181] 10…Laser processing device; 11…Laser source; 12…Spatial light modulator; 13…Dichroic mirror; 14…Converging optical system; 15…Drive unit; 16…Observation light source; 17…Photodetector; 18…Control unit; 110…Workpiece; 112…Processing surface; 114…Geometric shape; 116, 118, 120…Beam profile; 122: Irradiation area; 124…Non-irradiation area; 181…CPU; 182…RAM; 183…ROM; 184…Input device; 185…Digital / analog converter; 186…Auxiliary storage device; 200…processed surface; 201…cell; 202…irradiation point; 203…processing shape; A…processed 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…driving voltage; W…processed object; W1…light irradiation surface; W2, W3, W4…surface; Wa, Wb, Wc, Wd, We…area.

Claims

1. A laser processing device comprising: a spatial light modulator that inputs laser light output from a laser source, creates a hologram that modulates the phase of the laser light in each of a plurality of two-dimensionally arranged pixels, and outputs laser light phase-modulated by the hologram; a focusing optical system, which is disposed after the spatial light modulator; and a control unit configured to cause the spatial light modulator to produce a hologram by simultaneously focusing the phase-modulated laser light output from the spatial light modulator onto a plurality of irradiation points on a workpiece through the focusing optical system; The workpiece contains two or more materials. The control unit independently controls the light intensity of at least two of the multiple irradiation points, and makes the light intensities of the at least two irradiation points different in multiple areas where the materials of the workpiece are different. The light intensities of the at least two irradiation points are independently controlled according to the respective materials of the at least two irradiation points, so that the processing speed is consistent at the at least two irradiation points.

2. The laser processing device according to claim 1, wherein: Also features: an observation light source for irradiating the workpiece with observation light; and a light detector for detecting the observation light reflected by the workpiece, The control unit detects a change in material at each irradiation point based on a detection result by the light detector, and changes the light intensity at each irradiation point according to the change in material.

3. The laser processing device according to claim 1, wherein The apparatus further comprises a storage unit that stores data related to the light intensity at each irradiation point in advance, corresponding to the material distribution of the workpiece. The control unit controls the light intensity at each irradiation point based on the data.

4. The laser processing device according to claim 2, wherein: The apparatus further comprises a storage unit that stores data related to the light intensity at each irradiation point in advance, corresponding to the material distribution of the workpiece. The control unit controls the light intensity at each irradiation point based on the data.

5. The laser processing device according to any one of claims 1 to 4, wherein: The control unit makes at least one of the shapes and sizes of the following two processed areas different from each other. The two processed areas are: a processed area defined by the multiple irradiation points in a first plane intersecting the optical axis of the phase-modulated laser irradiated on the workpiece, and a processed area defined by the multiple irradiation points in a second plane intersecting the optical axis and separated from the first plane along the optical axis direction.

6. The laser processing device according to any one of claims 1 to 4, wherein: The control unit causes the spatial light modulator to sequentially present a plurality of holograms in which the position of each irradiation point is changed along an imaginary line defining a processed region defined by the plurality of irradiation points.

7. The laser processing device according to claim 5, wherein: The control unit causes the spatial light modulator to sequentially present a plurality of holograms in which the position of each irradiation point is changed along an imaginary line defining a processed region defined by the plurality of irradiation points.

8. The laser processing device according to any one of claims 1 to 4, wherein: When changing the hologram, the control unit causes the spatial light modulator to present a hologram in which the light intensity of the laser light is set to be less than a processing threshold at any portion of the workpiece during a period from erasing a certain hologram to presenting another hologram.

9. The laser processing device according to claim 5, wherein: When changing the hologram, the control unit causes the spatial light modulator to present a hologram in which the light intensity of the laser light is set to be less than a processing threshold at any portion of the workpiece during a period from erasing a certain hologram to presenting another hologram.

10. The laser processing device according to claim 6, wherein: When changing the hologram, the control unit causes the spatial light modulator to present a hologram in which the light intensity of the laser light is set to be less than a processing threshold at any portion of the workpiece during a period from erasing a certain hologram to presenting another hologram.

11. The laser processing apparatus according to claim 7, wherein: When changing the hologram, the control unit causes the spatial light modulator to present a hologram in which the light intensity of the laser light is set to be less than a processing threshold at any portion of the workpiece during a period from erasing a certain hologram to presenting another hologram.

12. A laser processing method, wherein: Repeat: a control step of causing the spatial light modulator to present a hologram of the phase of the modulated light at each of the plurality of pixels arranged two-dimensionally; A light modulation step of inputting laser light output from a laser source into the spatial light modulator and performing phase modulation of the laser light by the hologram; and A focusing step of focusing the phase-modulated laser light. In the control step, the spatial light modulator is caused to present a hologram in which the phase-modulated laser light output from the spatial light modulator is simultaneously focused and irradiated on a plurality of irradiation points of the workpiece by the focusing step. The workpiece contains two or more materials. In the control step, the light intensities of at least two of the multiple irradiation points are controlled independently of each other, and in multiple areas where the materials of the workpiece are different, the light intensities of the at least two irradiation points are made different from each other. The light intensities of the at least two irradiation points are controlled independently of each other according to the respective materials of the at least two irradiation points, so that the processing speed is made consistent at the at least two irradiation points.

13. The laser processing method according to claim 12, wherein: The method further comprises: a light detection step of irradiating the workpiece with observation light and detecting the observation light reflected from the workpiece; In the control step, based on the detection result of the light detection step, a change in the material at each irradiation point is detected, and the light intensity at each irradiation point is changed according to the change in the material.

14. The laser processing method according to claim 12, wherein: Before the control step, the method further includes: a storage step of pre-storing data related to the light intensity of each irradiation point corresponding to the material distribution of the workpiece; In the control step, the light intensity of each irradiation point is controlled based on the data.

15. The laser processing method according to claim 13, wherein: Before the control step, the method further includes: a storage step of pre-storing data related to the light intensity of each irradiation point corresponding to the material distribution of the workpiece; In the control step, the light intensity of each irradiation point is controlled based on the data.

16. The laser processing method according to any one of claims 12 to 15, wherein: In the control step, at least one of the shapes and sizes of the following two processed areas is made different from each other. The two processed areas are: a processed area defined by the multiple irradiation points in a first plane intersecting the optical axis of the phase-modulated laser irradiated on the workpiece, and a processed area defined by the multiple irradiation points in a second plane intersecting the optical axis and separated from the first plane along the optical axis direction.

17. The laser processing method according to any one of claims 12 to 15, wherein: In the control step, the spatial light modulator is caused to sequentially present a plurality of holograms in which the position of each irradiation point is changed along an imaginary line defining a processed region defined by the plurality of irradiation points.

18. The laser processing method according to claim 16, wherein: In the control step, the spatial light modulator is caused to sequentially present a plurality of holograms in which the position of each irradiation point is changed along an imaginary line defining a processed region defined by the plurality of irradiation points.

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

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

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

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

Images