Laser processing device

Abstract

This laser processing device comprises a light source that emits laser light, a first branching portion that causes the laser light emitted from the light source to branch into processing light and monitoring light, and a monitoring portion that acquires a plurality of measured values from the monitoring light, wherein the monitoring portion includes: a first lens and a second lens that are arranged on an optical path of the monitoring light; a second branching portion that polarizes and separates the monitoring light into first monitoring light and second monitoring light; a merging portion that causes the first monitoring light and the second monitoring light to merge to form the monitoring light, and emits the same; a detecting portion that detects the monitoring light emitted from the merging portion to form monitoring data indicating the intensity distribution of the monitoring light; and an analyzing portion that subjects one item of the monitoring data to a plurality of types of analysis to acquire a plurality of types of the measured values.

Description

Laser Processing Equipment

[0001] The present disclosure relates to a laser processing apparatus.

[0002] Patent Document 1 describes a laser light source device having an optical sensor unit for measuring the beam profile and beam pointing of laser light. In this laser light source device, laser light transmitted through a reflecting mirror is split into reflected light and transmitted light by a beam splitter. The transmitted light is focused by a focusing lens on a two-dimensional infrared sensor and used to measure the pointing state. Meanwhile, the reflected light is transferred by a transfer lens onto another two-dimensional infrared sensor to form an image and used to measure the beam profile.

[0003] JP 2016-58742 A

[0004] In a laser processing device that irradiates a workpiece with laser light, processing defects may occur due to deviations in the output position or output angle or changes in the divergence angle caused by aging or environmental factors (ambient temperature, vibration, impact, etc.) in the laser body or light guide optical system. In order to prevent such processing defects, it is necessary to obtain multiple measurement values ​​such as the beam profile and beam pointing of the laser light.

[0005] To achieve this, it is conceivable to adopt a configuration in which laser light is split into multiple beams, each beam is made incident on an infrared sensor via a predetermined optical system, and multiple measurement values ​​of the laser light are obtained based on the detection results of the infrared sensor, as in the laser light source device described in Patent Document 1. However, in this case, the optical systems and infrared sensors, as well as software for analyzing the detection results of each infrared sensor, are required for each measurement value to be obtained, making the device complex and expensive.

[0006] Therefore, an object of one aspect of the present disclosure is to provide a laser processing apparatus that can perform multiple measurements while suppressing the complexity and high cost of the apparatus.

[0007] A laser processing apparatus according to one aspect of the present disclosure includes: [1] "a light source that emits laser light; a first branching unit that branches the laser light emitted from the light source into processing light and monitor light; and a monitor unit that acquires a plurality of measurement values ​​from the monitor light, wherein the monitor unit includes a first lens and a second lens arranged on an optical path of the monitor light; a second branching unit that polarizes and separates the monitor light into first monitor light and second monitor light; a merging unit that configures the monitor light by merging the first monitor light and the second monitor light and emits the monitor light; a detection unit that detects the monitor light emitted from the merging unit to form monitor data indicating an intensity distribution of the monitor light; and a detection unit that generates monitor data for one of the monitor data, the plurality of types of monitor data for one of the monitor data. and an analysis unit that acquires the plurality of types of measurement values ​​by performing a plurality of analyses of the plurality of types of monitor light, wherein the first lens is arranged so that only the first monitor light of the monitor light passes through, the second lens is arranged so that the monitor light including the first monitor light and the second monitor light passes through, the first monitor light is imaged on the light incident surface of the detection unit by the first lens and the second lens, and the second monitor light is condensed on the light incident surface by the second lens, and the analysis unit acquires, as the measurement values, a first measurement value based on the first monitor light and a second measurement value based on the second monitor light by analyzing one of the monitor data.

[0008] In this laser processing apparatus, monitor light split from the laser light is split into first and second monitor lights by a second splitter. The first and second monitor lights are joined by a joining unit to form a monitor light again, which is then detected by a detector. At this time, the first monitor light is imaged on the light incident surface of the detector by the first and second lenses, and the second monitor light is focused on the light incident surface of the detector by the second lens. That is, in the monitor light detected by the detector, the focused state of the first monitor light differs from the focused state of the second monitor light. As a result, by analyzing a single monitor data piece formed by the detector, it is possible to obtain multiple measurement values, such as a first measurement value based on the first monitor light and a second measurement value based on the second monitor light. In this way, in this laser processing apparatus, the multiple light beams for obtaining multiple measurement values ​​are joined and detected by a single detector, while at least partially sharing the optical system (second lens) between the multiple light beams. Therefore, this laser processing device makes it possible to perform multiple measurements while preventing the device from becoming too complicated and expensive.

[0009] The laser processing device according to one aspect of the present disclosure may be [2] "the laser processing device according to the above [1], wherein the analyzer acquires the beam diameter of the monitor light as the first measurement value by performing a Gaussian fit on the monitor data." In this case, a change in the beam diameter of the laser light can be detected.

[0010] The laser processing device according to one aspect of the present disclosure may be [3] "the laser processing device according to the above [1] or [2], wherein the analyzer performs a centroid calculation on the monitor data to obtain the incident position of the monitor light on the light incident surface as the first measurement value." In this case, a change in the incident position of the laser light can be detected.

[0011] A laser processing device according to one aspect of the present disclosure may be [4] "the laser processing device according to any one of the above [1] to [3], wherein the analyzer obtains the maximum intensity value of the monitor light and the focusing position as the second measurement value by extracting the maximum value of the intensity of the monitor light in the monitor data." In this case, a change in the emission angle of the laser light can be detected based on the focusing position of the monitor light, and a change in the divergence angle of the laser light can be detected based on the maximum intensity value of the monitor light.

[0012] The laser processing device according to one aspect of the present disclosure may be [5] "the laser processing device according to any one of [1] to [4] above, wherein the second lens is disposed after the junction in the optical path of the monitor light." In this case, the optical path length from the light incident surface to the second lens can be shortened to reduce the diameter of the focused light on the light incident surface, thereby enabling the incident position of the laser light to be measured with high resolution.

[0013] The laser processing device according to one aspect of the present disclosure may be [6] "the laser processing device according to any one of [1] to [4] above, wherein the second lens is disposed in the optical path of the monitor light before the second branching portion." In this case, by lengthening the optical path length from the light incident surface to the second lens, the diameter of the focused light at the light incident surface can be increased, thereby suppressing damage to the detection unit.

[0014] A laser processing device according to one aspect of the present disclosure may be [7] "the laser processing device according to any one of the above [1] to [6], wherein the monitor unit further includes a wave plate that adjusts the polarization component of the monitor light, and the wave plate is disposed in the optical path of the monitor light before the second branch unit." In this case, the light intensity ratio between the first monitor light and the second monitor light can be adjusted by adjusting the polarization component of the monitor light using the wave plate.

[0015] A laser processing device according to one aspect of the present disclosure may be [8] "the laser processing device according to any one of [1] to [7] above, wherein the focal length of one of the first and second lenses that is located farther from the detection unit is equal to or shorter than the optical path length from the light source to the one lens, and the focal length of the other of the first and second lenses is equal to the optical path length from the other lens to the light incident surface." In this case, since the focal position of one lens is between the light source and the one lens and the focal position of the other lens is on the light incident surface, the laser light can be more accurately imaged on the light incident surface. Therefore, changes in the beam diameter and incident position of the laser light can be more accurately detected.

[0016] The laser processing device according to one aspect of the present disclosure may be [9] "the laser processing device according to any one of [1] to [8] above, wherein the focal length of the second lens is equal to the optical path length from the second lens to the light incident surface." In this case, it is possible to more accurately detect changes in the optical axis angle of the laser beam and changes in the divergence angle of the laser beam.

[0017] A laser processing device according to one aspect of the present disclosure may be

[10] "the laser processing device according to any one of [1] to [9] above, in which the optical path length of the monitor light from the first branching unit to the light incident surface is shorter than the optical path length of the processing light from the first branching unit to the processing surface onto which the processing light is irradiated," or

[11] "the laser processing device according to any one of [1] to

[10] above, in which the optical path length of the monitor light from the first branching unit to the light incident surface is 300 mm or less." In these cases, changes in the monitor light caused by an optical system through which the monitor light in the monitor unit passes can be suppressed.

[0018] The laser processing device according to one aspect of the present disclosure may be

[12] "the laser processing device according to any one of [1] to

[11] above, wherein, on the light incident surface, the focusing position of the second monitor light is located in an area that is within 50% of the distance from the beam center to the beam outer edge of the first monitor light." In this case, when a Gaussian fit is performed on the monitor data, the second monitor light can be prevented from becoming noise.

[0019] The laser processing device according to one aspect of the present disclosure may be

[13] "the laser processing device according to any one of the above [1] to

[12] , wherein the optical path length between the first lens and the second lens is equal to the sum of the focal length of the first lens and the focal length of the second lens." In this case, it is possible to suppress a change in the optical axis of the monitor light caused by the optical system of the monitor unit through which the monitor light passes.

[0020] According to one aspect of the present disclosure, it is possible to provide a laser processing device that can perform multiple measurements simultaneously while keeping the cost of the device low.

[0021] FIG. 1 is a schematic diagram showing a laser processing apparatus according to this embodiment. FIG. 2 is a display example of monitor data showing the intensity distribution of monitor light. FIG. 3(a) is a display example of comparison data showing the intensity distribution of only the first monitor light, and FIG. 3(b) is a display example of comparison data showing the intensity distribution of only the second monitor light. FIG. 4 is a diagram for explaining the analysis processing performed by each function of the analysis unit on the monitor data. FIGS. 5(a) to 5(c) are diagrams for explaining the analysis processing of the analysis unit in detail. FIG. 6 is a diagram for explaining the focus position of the second monitor light. FIG. 7 is a diagram for explaining changes in the beam profile of the laser light due to optical axis shift. FIG. 8(a) is a diagram for explaining changes in the position of the focus pattern of the laser light due to the tilt angle of the optical axis, and FIG. 8(b) is a diagram for explaining changes in peak intensity due to the divergence angle of the laser light. FIG. 9 is a schematic diagram showing a laser processing apparatus according to a modified example.

[0022] Hereinafter, a laser processing apparatus according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant description may be omitted.

[0023] FIG. 1 is a schematic diagram showing a laser processing apparatus according to this embodiment. As shown in FIG. 1, the laser processing apparatus 1 includes a light source 2, a first branching unit 3, a lens 4, a monitor unit 5, a mirror 6, and a mirror 7. The laser processing apparatus 1 is configured to perform laser processing of a workpiece 10, such as a semiconductor wafer, by irradiating the workpiece 10 with laser light. More specifically, the laser processing apparatus 1 causes the light source 2 to emit laser light L1, splits the laser light L1 using the first branching unit 3 to generate processing light (laser light) L2, and focuses the processing light L2 toward a processing surface 10a of the workpiece 10 using the lens 4, thereby performing laser processing of the workpiece 10. Each component will be described in detail below.

[0024] The light source 2 emits laser light L1. The first branching unit 3 is disposed on the optical path of the laser light L1. The first branching unit 3 branches the laser light L1 emitted from the light source 2 into processing light L2 and monitor light L3. The first branching unit 3 is, for example, a beam sampler, and can branch the laser light L1 into processing light L2 and monitor light L3 by reflecting a portion of the laser light L1 as monitor light L3 and transmitting the remaining portion of the laser light L1 as processing light L2.

[0025] The lens 4 is disposed on the optical path of the processing light L2 branched by the first branching section 3. The lens 4 is, for example, an objective lens, and focuses the processing light L2 toward the processing surface 10a of the workpiece 10. The mirrors 6 and 7 are disposed in this order on the optical path of the laser light L1, between the light source 2 and the first branching section 3. The mirrors 6 and 7 sequentially reflect the laser light L1 emitted from the light source 2 and cause it to enter the first branching section 3. The laser processing apparatus 1 may include a mechanism for adjusting the divergence angle of the laser light L1, such as a collimator lens or a beam expander, between the light source 2 and the first branching section 3.

[0026] The monitor unit 5 receives the monitor light (laser light) L3 branched by the first branch unit 3 and acquires a plurality of measurement values ​​of the laser light L1 (e.g., beam profile, beam pointing, and collimation state) using the monitor light L3. The monitor unit 5 has an optical system 20, a detection unit 30, and an analysis unit 40. The optical system 20 causes the monitor light L3 emitted from the first branch unit 3 to be incident on a light incident surface 30a of the detection unit 30.

[0027] The optical system 20 includes a mirror 21, a wave plate 22, a second branching unit 23, a first lens 24, a combining unit (wave combining unit) 25, a second lens 26, a mirror 27a, and a mirror 27b. The optical system 20 branches the monitor light L3 from the first branching unit 3 into first monitor light L31 and second monitor light L32 by the second branching unit 23, and combines the first monitor light L31 and the second monitor light L32 by the combining unit 25 to form monitor light L3 again, which is incident on the light incident surface 30a of the detection unit 30. Next, each component of the optical system 20 will be described in detail.

[0028] The mirror 21 and the wave plate 22 are arranged in this order on the optical path of the monitor light L3 between the first branching unit 3 and the second branching unit 23. The mirror 21 reflects the monitor light L3 emitted from the first branching unit 3 and makes it incident on the wave plate 22. The wave plate 22 adjusts the polarization direction of the monitor light L3 reflected by the mirror 21 and emits it toward the second branching unit 23. In other words, the wave plate 22 is arranged before the second branching unit 23 on the optical path of the monitor light L3.

[0029] The second splitter 23 is, for example, a polarizing beam splitter, and splits the monitor light L3 output from the wave plate 22 into a first monitor light L31 and a second monitor light L32 by polarization. For example, the second splitter 23 transmits the p-polarized component of the monitor light L3 as the first monitor light L31 and reflects the s-polarized component of the monitor light L3 as the second monitor light L32, thereby splitting the monitor light L3 into the first monitor light L31 and the second monitor light L32. The first monitor light L31 is used to measure a first measurement value of the laser light L1, and the second monitor light L32 is used to measure a second measurement value of the laser light L1.

[0030] As will be described later, the first monitor light L31 is imaged on the light incident surface 30a of the detecting unit 30 by the first lens 24 and the second lens 26, and the second monitor light L32 is condensed on the light incident surface 30a by the second lens 26. Therefore, the light intensity ratio between the first monitor light L31 and the second monitor light L32 can be set so that saturation due to the second monitor light L32 does not occur in the detecting unit 30. As an example, the light intensity ratio may be set so that the light intensity of the first monitor light L31 is about 80% of the light intensity of the monitor light L3, and the light intensity of the second monitor light L32 is about 20% of the light intensity of the monitor light L3. In this case, the wavelength plate 22 is set to change the polarization direction of the monitor light L3 so that when the polarization component ratio of the monitor light L3 before passing through the wavelength plate 22 is 0% p-polarized component and 100% s-polarized component, the polarization component ratio of the monitor light L3 after passing through the wavelength plate 22 becomes 80% p-polarized component and 20% s-polarized component.

[0031] The first lens 24 and the second lens 26 are disposed on the optical path of the monitor light L3. More specifically, the first lens 24 is disposed on the optical path of the first monitor light L31, between the second branching section 23 and the merging section 25. Therefore, the second monitor light L32 does not pass through the first lens 24. That is, the first lens 24 is disposed so that only the first monitor light L31 passes through. The focal length of the first lens 24 is equal to or less than the optical path length from the light source 2 to the first lens 24. As a result, the front focus of the first lens 24 is positioned between the light source 2 and the first lens 24.

[0032] The combining unit 25 is, for example, a polarizing beam splitter, and combines the first monitor light L31 and the second monitor light L32, which have been polarized and separated by the second branching unit 23, to form and emit monitor light L3 again. The monitor light L3 emitted from the combining unit 25 passes through a second lens 26 and is incident on the light incident surface 30a of the detecting unit 30.

[0033] The second lens 26 is disposed between the junction 25 and the detection unit 30 on the optical path of the monitor light L3 emitted from the junction 25. That is, the second lens 26 is disposed so that the monitor light L3 including the first monitor light L31 and the second monitor light L32 passes through the second lens 26. In this embodiment, of the first lens 24 and the second lens 26, the first lens 24 corresponds to one lens disposed farther from the detection unit 30 (light incident surface 30a), and the second lens 26 corresponds to the other lens. The mirrors 27a and 27b are disposed in order on the optical path of the second monitor light L32 so as to sequentially reflect the second monitor light L32 branched at the second branch 23 and cause it to enter the junction 25.

[0034] The focal length of the second lens 26 is equal to the optical path length from the second lens 26 to the light incident surface 30a. As a result, the rear focal point of the second lens 26 is positioned on the light incident surface 30a. The optical path length between the first lens 24 and the second lens 26 is equal to the sum of the focal length of the first lens 24 and the focal length of the second lens 26. As a result, the rear focal point of the first lens 24 and the front focal point of the second lens 26 are made to coincide. As a result, the first lens 24 and the second lens 26 form an optical image of the first monitor light L31 (an optical image at the front focal point of the first lens 24) on the light incident surface 30a, and the second monitor light L32 is condensed on the light incident surface 30a.

[0035] In addition, the optical path length of the monitor light L3 from the first branching section 3 to the light incident surface 30a, i.e., the total optical path length of the monitor light L3 from the first branching section 3 to the second branching section 23, the optical path length of the first monitor light L31 (or the second monitor light L32) from the second branching section 23 to the confluence section 25, and the optical path length of the monitor light L3 from the confluence section 25 to the light incident surface 30a, is, for example, 300 mm or less, which is shorter than the optical path length of the processing light L2 from the first branching section 3 to the processing surface 10a onto which the processing light L2 is irradiated.

[0036] As described above, the first monitor light L31 branched by the second branching section 23 is imaged on the light incident surface 30a of the detection section 30 by the first lens 24 and the second lens 26, and the second monitor light L32 branched by the second branching section 23 does not pass through the first lens 24 but is focused on the light incident surface 30a by the second lens 26.

[0037] The detection unit 30 generates monitor data DM (see FIG. 2 ) that indicates the intensity distribution of the monitor light L3 emitted from the confluence unit 25. The detection unit 30 is, for example, a sensor having a light incident surface 30a configured with pixels arranged two-dimensionally. The detection unit 30 may include an image forming unit that forms a monitor image M (described below) from the monitor data DM. The image forming unit may be formed integrally with the detection unit 30 or may be arranged separately from the detection unit 30 (e.g., a computer connected to the detection unit 30). The detection unit 30 may also be an image sensor or the like.

[0038] The monitor data DM will be described with reference to FIGS. 2 and 3. FIG. 2 is a display example of the monitor data DM, which is a monitor image M showing the intensity distribution of the monitor light L3. In the monitor image M shown in FIG. 2, the intensity distribution is indicated by color shading. Furthermore, in the monitor image M, an intensity distribution A1 in a cross section passing through a point on the monitor image M is superimposed on an intensity distribution A2 in another cross section (a cross section perpendicular to the cross section) passing through the same point on the image. The reference point on the cross section is, for example, a point (pixel) corresponding to the focusing position P of the monitor light L3. The monitor image M shown in FIG. 2 corresponds to a sum of an image M1 of a display example of comparison data showing the intensity distribution when only the first monitor light L31 is captured as shown in FIG. 3(a) and an image M2 of a display example of comparison data showing the intensity distribution when only the second monitor light L32 is captured as shown in FIG. 3(b).

[0039] 1 analyzes the monitor data DM generated by the detection unit 30. The analysis unit 40 is configured as a computer device including a processor, memory, storage, and communication devices. In the analysis unit 40, software (programs) loaded into the memory are executed by the processor, and the processor controls the reading and writing of data in the memory and storage, as well as communication by the communication devices. In this way, the analysis unit 40 realizes various functions.

[0040] The analysis unit 40 will be described below with reference to Figs. 4 and 5. Fig. 4 is a diagram for explaining the functions of the analysis unit 40. Fig. 5 is a diagram for explaining the analysis processing performed by each function of the analysis unit 40 on the monitor data DM. Each diagram in Fig. 5 shows the intensity distribution of a monitor image M, which is a display example of the monitor data DM. The horizontal axis represents the position on the monitor image M (pixels on the light incident surface 30a). The vertical axis represents the intensity of the monitor light L3.

[0041] 4, the analysis unit 40 includes a data acquisition unit 41, a maximum value position detection unit 42, a fitting unit 43, a binarization processing unit 44, and a center of gravity calculation unit 45. The analysis unit 40 acquires multiple types of measurement values ​​by performing multiple types of analyses on one piece of monitor data DM indicating the intensity distribution of the monitor light L3. Specifically, the analysis unit 40 analyzes the one piece of monitor data DM to acquire, as measurement values, a first measurement value based on the first monitor light L31 and a second measurement value based on the second monitor light L32.

[0042] The data acquiring unit 41 acquires the monitor data DM formed by the detecting unit 30. The data acquiring unit 41 outputs the monitor data DM to the maximum value position detecting unit .

[0043] As shown in FIG. 5A, the maximum value position detector 42 extracts the maximum intensity value I1 of the monitor light L3 from the intensity distribution A (the intensity distribution A1 or A2) of the monitor data DM. This obtains the focusing position P (beam pointing) in a plane intersecting the optical axis of the monitor light L3 as the position where the maximum value I1 is obtained. The maximum value position detector 42 also obtains the collimation state of the laser light L1 based on the maximum intensity value I1 of the monitor light L3 and the characteristics of an optical system (e.g., the second lens 26) for focusing the second monitor light L32 on the light incident surface 30a. As an example, the collimation state can be obtained by comparing the maximum intensity value (peak intensity) of the monitor light L3 detected when the divergence angle of the laser light L1 is a reference value with the actually detected maximum value I1 (peak intensity) based on the characteristics of the second lens 26.

[0044] In the intensity distribution A of the monitor data DM, a peak is formed and a maximum value is provided by the second monitor light L32 of the monitor light L3 that is focused on the light incident surface 30a. Therefore, the focusing position P is also the focusing position of the second monitor light L32. Therefore, the maximum value I1 and the focusing position P are based on the second monitor light L32 of the monitor light L3, and are acquired as the second measurement value.

[0045] 5B, the fitting unit 43 first performs a Gaussian fit on the intensity distribution A of the monitor data DM. Specifically, the fitting unit 43 creates an intensity distribution (approximation curve) F that approximates the intensity distribution A by fitting the intensity distribution A of the monitor data DM based on a Gaussian function.

[0046] Next, the fitting unit 43 obtains the beam diameter of the monitor light L3 using the intensity distribution F. To this end, the fitting unit 43 first obtains the beam diameter of the monitor light L3 based on the intensity distribution F. ２Here, the positions of the two points indicating the outer edge of the beam in the intensity distribution F are defined as positions d1 and d2, respectively. The fitting unit 43 then obtains the distance between positions d1 and d2 indicating the outer edge of the beam (position d2 - position d1) as the beam diameter of the monitor light L3. Note that the intensity distribution F is formed by a portion of the intensity distribution A other than the peak due to the second monitor light L32 being dominant. Therefore, the intensity distribution F is formed mainly based on the first monitor light L31. For this reason, the beam diameter of the monitor light L3 is also the beam diameter of the first monitor light L31, and is obtained as a first measurement value based on the first monitor light L31.

[0047] 5(c), the binarization processing unit 44 binarizes the intensity distribution A of the monitor data DM to obtain a binarized intensity distribution G. The binarization processing unit 44 may also perform binarization based on the intensity distribution F. The binarization processing unit 44 outputs data indicating the binarized intensity distribution G to the center of gravity calculation unit 45.

[0048] The center of gravity calculation unit 45 obtains the beam center C of the monitor light L3 (i.e., the incident position of the monitor light L3 on the light incident surface 30a) by performing a center of gravity calculation on the binarized intensity distribution G output from the binarization processing unit 44. Note that the intensity distribution G is formed mainly based on the first monitor light L31. Therefore, the beam center C of the monitor light L3 is also the incident position of the first monitor light L31 on the light incident surface 30a, and is obtained as a first measurement value based on the first monitor light L31.

[0049] FIG. 6 is a diagram illustrating the relationship between the focusing position P, beam center C, and beam outer edge of the monitor light L3. The horizontal and vertical axes are the same as those in FIG. 5 . FIG. 6 shows the beam center C, focusing position P, region R1, and region R2 of the monitor light L3. In FIG. 6, the beam center C and the focusing position P coincide with each other. Region R1 indicates the region between the beam outer edges detected by the fitting unit 43. That is, the length of region R1 corresponds to the beam diameter of the monitor light L3. Region R2 indicates a region within 50% of the distance from the beam center C to the beam outer edge. That is, the distance from the beam center C to the outer edge of region R2 is 50% of the distance from the beam center C to the outer edge of region R1. As shown in FIG. 6 , the focusing position P is located in region R2. That is, the monitor light L3 is adjusted by the optical system 20 or the like so that the focusing position P is located in region R2.

[0050] 6 illustrates a case where the light-focusing position P and the beam center C coincide with each other. However, the light-focusing position P and the beam center C may be misaligned within a certain range. The region R2 indicates the range of this misalignment. That is, on the light incident surface 30a, the light-focusing position P may be located in the region R2 that is within 50% of the distance from the beam center C to the outer edge of the beam.

[0051] As described above, in a laser processing device, deviations in the emission position and emission angle, and changes in the divergence angle may occur due to factors that depend on the laser body or light-guiding optical system over time or on the environment (e.g., ambient temperature, vibration, impact, etc.).

[0052] A shift in the emission position of the laser beam causes a shift in the optical axis of the laser beam incident on the objective lens (optical axis shift). A shift in the optical axis incident on the objective lens (i.e., a change in the incident position on the objective lens) disrupts the focused light pattern on the processing surface. Such optical axis shift can be confirmed by detecting the position of the laser beam based on the beam profile of the laser beam. Specifically, as shown in FIG. 7 , when an optical axis shift occurs, the beam incident position (beam center) shifts. Each graph in FIG. 7 shows the beam profile of the laser beam when no optical axis shift occurs (reference (no movement)) and when the optical axis shift occurs by values ​​ranging from 0.25 mm to 1.0 mm. In the laser processing apparatus 1 according to this embodiment, the monitor unit 5 acquires the beam center C based on the intensity distribution (beam profile) of the monitor light L3. Therefore, the optical axis shift can be confirmed based on this beam center C.

[0053] Furthermore, deviations in the emission angle (angular deviation) of the laser beam tilt the optical axis incident on the objective lens. When the optical axis incident on the objective lens is tilted, the position of the laser beam focusing pattern on the processing surface shifts relative to the principal axis of the objective lens, as shown in FIG. 8(a). Each graph in FIG. 8(a) shows the focusing pattern of the laser beam when the optical axis is not tilted (reference (no tilt)) and when the optical axis is tilted by values ​​ranging from 0.2° to 1.0°. Such angular deviations can be confirmed by detecting the optical axis angle (tilt angle) through beam pointing of the laser beam. In the laser processing apparatus 1 according to this embodiment, the monitor unit 5 acquires the focusing position P (beam pointing) of the monitor light L3. Therefore, the optical axis angle can be detected based on this focusing position P, and the angular deviation can be confirmed.

[0054] Furthermore, a change in the divergence angle of the laser beam changes the focal position of the laser beam in the optical axis direction of the laser beam. In other words, a change in the divergence angle of the laser beam changes the focal position of the laser beam in the optical axis direction of the laser beam, resulting in a change (decrease) in the peak intensity of the laser beam, as shown in FIG. 8B. The graphs in FIG. 8B show the peak intensity of the laser beam when the divergence angle is 0.1 mrad (reference) and 0.5 mrad. Therefore, a change in the divergence angle can be confirmed by detecting the collimation state of the laser beam (i.e., a change in peak intensity). In the laser processing apparatus 1 according to this embodiment, the monitor unit 5 acquires the collimation state of the laser beam L1 based on the maximum intensity I1 of the monitor beam L3. Therefore, a change in the divergence angle of the laser beam L1 can be confirmed based on this collimation state.

[0055] In addition, in the past, in order to obtain the collimated state of the laser light, it was necessary to move a detector such as a camera along the optical axis of the laser light. On the other hand, with the laser processing device 1, the collimated state of the laser light L1 can be obtained based on the maximum intensity I1 of the monitor light L3, so there is no need to move the detector 30. [Operation and Effects]

[0056] As described above, in the laser processing apparatus 1, the monitor light L3 branched from the laser light L1 is branched into the first monitor light L31 and the second monitor light L32 by the second branching unit 23. The first monitor light L31 and the second monitor light L32 are merged by the merging unit 25 to form the monitor light L3 again, which is then detected by the detecting unit 30. At this time, the first monitor light L31 is imaged on the light incident surface 30a of the detecting unit 30 by the first lens 24 and the second lens 26, and the second monitor light L32 is focused on the light incident surface 30a of the detecting unit 30 by the second lens 26. That is, in the monitor light L3 detected by the detecting unit 30, the focused state of the first monitor light L31 and the focused state of the second monitor light L32 are different. As a result, by analyzing one piece of monitor data DM formed by the detection unit 30, it is possible to obtain multiple measurement values, such as a first measurement value (beam diameter, beam center C) based on the first monitor light L31 and a second measurement value (maximum value I1, light focus position P) based on the second monitor light L32. In this way, in this laser processing apparatus 1, the optical system (second lens 26) is at least partially shared among the multiple light beams used to obtain multiple measurement values, and the multiple light beams are merged and detected by a single detection unit 30. Therefore, this laser processing apparatus 1 makes it possible to perform multiple measurements while minimizing the complexity and cost of the apparatus. Minimizing the complexity of the apparatus also makes it possible to reduce the size of the apparatus.

[0057] Furthermore, the laser processing device 1 can record each parameter during processing by monitoring each parameter of the first measurement value and the second measurement value. Furthermore, it can detect shifts and inclinations of the processing optical axis and changes in the beam diameter during processing, making it possible to provide a stable processing process.

[0058] As described above, the monitor light L3 is polarized and split into the first monitor light L31 and the second monitor light L32 at the second branching unit 23. Therefore, since the first monitor light L31 and the second monitor light L32 have different polarization components, even if both monitor light beams are simultaneously incident on one detecting unit 30, interference between the two monitor light beams can be suppressed.

[0059] The fitting unit 43 of the analysis unit 40 performs a Gaussian fit on the intensity distribution F of the monitor data DM to obtain the beam diameter of the monitor light L3 as a first measurement value, thereby making it possible to detect a change in the beam diameter of the laser light L1.

[0060] The center of gravity calculation unit 45 obtains the beam center C of the monitor light L3 on the light incident surface 30a as a first measurement value by performing a center of gravity calculation on the binarized intensity distribution G output from the binarization processing unit 44. This makes it possible to detect a change in the incident position of the laser light L1 with respect to the objective lens (i.e., optical axis shift).

[0061] The maximum value position detector 42 extracts the maximum value I1 of the intensity of the monitor light L3 from the intensity distribution A of the monitor data DM, and thereby obtains the maximum value I1 of the intensity of the monitor light L3 and the focusing position P on the light incident surface 30a as a second measurement value based on the second monitor light L32. This makes it possible to detect the tilt (angle deviation) of the optical axis incident on the lens 4 caused by a deviation in the emission angle of the laser light L1 based on the focusing position P, and also to detect a change in the divergence angle of the laser light L1 based on the maximum value I1.

[0062] Here, if the laser processing device 1 is provided with a mechanism for adjusting the spread angle of the laser light, such as a collimator lens or an expander, between the light source 2 and the first branching section 3, the spread angle of the laser light L1 can be adjusted by adjusting these mechanisms so that the maximum value I1 obtained as the second measurement value becomes larger, and processing defects caused by changes in the spread angle can be suppressed.

[0063] The second lens 26 is disposed on the third optical path of the monitor light L3 between the junction 25 and the detection unit 30. That is, the second lens 26 is disposed after the junction 25 on the optical path of the monitor light L3. This shortens the optical path length from the light incident surface 30a to the second lens 26, thereby reducing the diameter of the focused light on the light incident surface 30a. Therefore, the incident position of the laser light can be measured with high resolution.

[0064] The wave plate 22 is disposed in the optical path of the monitor light L3 before the second branching unit 23. This makes it possible to adjust the light intensity ratio between the first monitor light L31 and the second monitor light L32 branched in the second branching unit 23 by adjusting the polarization component of the monitor light L3 in the wave plate 22. Furthermore, as described above, adjusting the light intensity ratio in the wave plate 22 makes it possible to suppress saturation caused by the second monitor light L32 in the detection unit 30.

[0065] The focal length of the first lens 24 is equal to or less than the optical path length from the light source 2 to the first lens 24, and the focal length of the second lens 26 is equal to the optical path length from the second lens 26 to the light incident surface 30a. That is, the focal length of one of the first and second lenses 24 and 26 (the first lens 24 in this embodiment), which is located farther from the detection unit 30, is equal to or less than the optical path length from the light source 2 to that lens, and the focal length of the other of the first and second lenses 24 and 26 (the second lens 26 in this embodiment) is equal to the optical path length from the other lens to the light incident surface 30a. As a result, in this embodiment, the front focal position of the first lens 24 is between the light source 2 and the first lens 24, and the focal position of the second lens 26 is on the light incident surface 30a, so that the laser light L1 can be more accurately imaged on the light incident surface 30a. Therefore, changes in the beam diameter and incident position of the laser light L1 can be more accurately detected.

[0066] The focal length of the second lens 26 is equal to the optical path length from the second lens 26 to the light incident surface 30 a. This allows the rear focal point of the second lens 26 to be positioned on the light incident surface 30 a. This makes it possible to more accurately detect changes in the optical axis angle of the laser light and changes in the divergence angle of the laser light.

[0067] The optical path length of the monitor light L3 from the first branching unit 3 to the light incident surface 30a is, for example, 300 mm or less, which is shorter than the optical path length of the processing light L2 from the first branching unit 3 to the processing surface 10a onto which the processing light L2 is irradiated. This makes it possible to suppress changes in the monitor light L3 caused by the optical system 20 through which the monitor light L3 of the monitor unit 5 passes.

[0068] On the light incident surface 30a, the focusing position P of the second monitor light L32 is located in a region R2 that is within 50% of the distance from the beam center C to the outer edge of the beam of the first monitor light L31. This makes it possible to prevent the second monitor light L32 from becoming noise when performing a Gaussian fit on the intensity distribution A of the monitor data DM.

[0069] The optical path length between the first lens 24 and the second lens 26 is equal to the sum of the focal lengths of the first lens 24 and the second lens 26. This causes the rear focal point of the first lens 24 to coincide with the front focal point of the second lens 26. As a result, the first lens 24 and the second lens 26 form an optical image of the first monitor light L31 (an optical image at the front focal point of the first lens 24) on the light incident surface 30a, and the second monitor light L32 is condensed on the light incident surface 30a. This makes it possible to suppress changes in the optical axis of the monitor light L3 caused by the optical system 20 of the monitor unit 5 through which the monitor light L3 passes. [Modification]

[0070] The above embodiment has described one aspect of the present disclosure. Therefore, the present disclosure is not limited to the above-described laser processing apparatus 1 and can be modified as desired.

[0071] Fig. 9 is a schematic diagram showing a laser processing apparatus according to a modified example. The laser processing apparatus 1A shown in Fig. 9 differs from the laser processing apparatus 1 according to the above embodiment in that the second lens 26 is arranged in the optical path of the monitor light L3 before the second branching unit 23. Specifically, in the laser processing apparatus 1A, the second lens 26 is arranged between the wave plate 22 and the second branching unit 23 on the optical path of the monitor light L3.

[0072] 9 , of the first lens 24 and the second lens 26, the second lens 26 corresponds to one lens arranged farther from the detection unit 30 (light incident surface 30 a), and the first lens 24 corresponds to the other lens. Therefore, in the example of FIG. 9 , the focal length of the second lens 26 is equal to or shorter than the optical path length from the light source 2 to the second lens 26, and the focal length of the first lens 24 is equal to the optical path length from the first lens 24 to the light incident surface 30 a. Also, in the example of FIG. 9 , the focal length of the second lens 26 may be equal to the optical path length from the second lens 26 to the light incident surface 30 a. In this case, since the second lens 26 has the function of focusing the second monitor light L32 on the light incident surface 30 a, the optical path length from the second lens 26 to the light incident surface 30 a is the optical path length including the optical path of the second monitor light L32 via the mirrors 27 a and 27 b.

[0073] 9, the optical path length from the light incident surface 30a to the second lens 26 can be increased, and the diameter of the collected monitor light L3 at the light incident surface 30a can be increased, thereby suppressing damage to the detection unit 30.

[0074] 9 , the focal length of one of the first lens 24 and the second lens 26 that is located farther from the detection unit 30 does not have to be equal to or shorter than the optical path length from the light source 2 to that one lens, and the focal length of the other of the first lens 24 and the second lens 26 does not have to be equal to the optical path length from the other lens to the light incident surface 30 a. Furthermore, the focal length of the second lens 26 does not have to be equal to the optical path length from the second lens 26 to the light incident surface 30 a. Furthermore, the optical path length between the first lens 24 and the second lens 26 does not have to be equal to the sum of the focal lengths of the first lens 24 and the second lens 26.

[0075] The present disclosure is not limited to the above-described embodiments and modifications, and various materials and shapes can be adopted for the materials and shapes of each component, without being limited to those described above.

[0076] For example, the polarization component ratio of the monitor light L3 after passing through the wave plate 22 is not limited to the ratio in the above embodiment. For example, by adjusting the wave plate 22 to change the polarization component ratio of the monitor light L3, it is possible to image only the first monitor light L31 on the detection unit 30. Similarly, by adjusting the wave plate 22, it is possible to focus only the second monitor light L32 on the detection unit 30. This makes it possible to optically switch between acquiring only the first measurement value or only the second measurement value.

[0077] In the above embodiment, the monitor unit 5 acquires the beam diameter of the monitor light L3 by performing Gaussian fitting on the monitor data DM. However, the monitor unit 5 may acquire the beam diameter of the monitor light L3 by any other method.

[0078] In the above embodiment, the monitor unit 5 acquires the beam center C by calculating the center of gravity of the intensity distribution G obtained by binarizing the intensity distribution A (or intensity distribution F) of the monitor light L3. However, the monitor unit 5 may acquire the beam center C based on the center of gravity of any intensity distribution (e.g., the intensity distribution A or the intensity distribution F) obtained from the monitor data DM, not limited to the binarized intensity distribution G. Furthermore, the monitor unit 5 may acquire the beam center C by other methods instead of calculating the center of gravity.

[0079] Furthermore, the optical path length of the monitor light L3 from the first branching section 3 to the light incident surface 30a may be longer than the optical path length of the processing light L2 from the first branching section 3 to the processing surface 10a onto which the processing light L2 is irradiated, or may be longer than 300 mm.

[0080] Furthermore, on the light incident surface 30a, the focusing position of the second monitor light L32 does not have to be located in the region R2 that is within 50% of the distance from the beam center C to the outer edge of the beam of the first monitor light L31.

[0081] 1, 1A...laser processing device, 2...light source, 3...first branching section, 5...monitor section, 10a...processing surface, 22...wave plate, 23...second branching section, 24...first lens, 25...confluence section, 26...second lens, 30...detection section, 30a...light incident surface, 40...analysis section, C...beam center (incident position), I1...maximum value, L1...laser light, L2...processing light, L3...monitor light, L31...first monitor light, L32...second monitor light, DM...monitor data, P...focusing position, R2...area.

Claims

a first branching section that splits the laser light emitted from the light source into processing light and monitor light; and a monitor section that acquires a plurality of measurement values ​​from the monitor light, wherein the monitor section has: a first lens and a second lens arranged on an optical path of the monitor light; a second branching section that polarizes and separates the monitor light into first monitor light and second monitor light; a junction section that configures the monitor light by merging the first monitor light and the second monitor light and emits the monitor light; a detection section that forms monitor data indicating an intensity distribution of the monitor light by detecting the monitor light emitted from the junction section; and an analysis section that acquires a plurality of types of the measurement values ​​by performing a plurality of types of analyses on one of the monitor data, wherein the first lens is arranged so that only the first monitor light of the monitor light passes through, and the second lens is arranged so that the monitor light including the first monitor light and the second monitor light passes through, and the first monitor light is imaged by the first lens and the second lens on a light incident surface of the detection section, the second monitor light is focused on the light incident surface by the second lens, and the analysis unit obtains, as the measurement values, a first measurement value based on the first monitor light and a second measurement value based on the second monitor light by analyzing one of the monitor data.

2. The laser processing device according to claim 1, wherein the analysis unit obtains the beam diameter of the monitor light as the first measurement value by performing a Gaussian fit on the monitor data.

3. The laser processing device according to claim 1 or 2, wherein the analysis unit performs a center of gravity calculation on the monitor data to obtain the incident position of the monitor light on the light incident surface as the first measurement value.

4. A laser processing device as described in any one of claims 1 to 3, wherein the analysis unit obtains the maximum intensity value of the monitor light and the focusing position as the second measurement value by extracting the maximum intensity value of the monitor light in the monitor data.

5. A laser processing device according to any one of claims 1 to 4, wherein the second lens is disposed in the optical path of the monitor light subsequent to the junction.

6. A laser processing device according to any one of claims 1 to 4, wherein the second lens is disposed in the optical path of the monitor light, before the second branching portion.

7. A laser processing device as claimed in any one of claims 1 to 6, wherein the monitor section further has a wave plate that adjusts the polarization component of the monitor light, and the wave plate is arranged in the optical path of the monitor light upstream of the second branch section.

8. A laser processing device as described in any one of claims 1 to 7, wherein the focal length of one of the first lens and the second lens that is arranged farther from the detection unit is equal to or less than the optical path length from the light source to that one lens, and the focal length of the other of the first lens and the second lens is equal to the optical path length from the other lens to the light incident surface.

9. A laser processing device according to any one of claims 1 to 8, wherein the focal length of the second lens is equal to the optical path length from the second lens to the light incident surface.

10. A laser processing device as described in any one of claims 1 to 9, wherein the optical path length of the monitor light from the first branching portion to the light incident surface is shorter than the optical path length of the processing light from the first branching portion to the processing surface onto which the processing light is irradiated.

11. The laser processing device according to any one of claims 1 to 10, wherein the optical path length of the monitor light from the first branching portion to the light incident surface is 300 mm or less.

12. A laser processing device as described in any one of claims 1 to 11, wherein, on the light incident surface, the focusing position of the second monitor light is located in an area that is within 50% of the distance from the beam center to the beam outer edge of the first monitor light.

13. A laser processing device according to any one of claims 1 to 12, wherein an optical path length between the first lens and the second lens is equal to the sum of a focal length of the first lens and a focal length of the second lens.

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