Laser processing device

Abstract

To provide a laser processing device capable of performing a plurality of measurement tasks while suppressing complication and cost increase of the device.SOLUTION: A laser processing device 1 comprises a monitoring portion 5 that acquires a plurality of measured values from monitoring light L3 branched from laser light L1. Therein the monitoring portion 5 includes: a first lens 24 and a second lens 26; a second branching portion 23 that polarizes and separates the monitoring light into first monitoring light L31 and second monitoring light L32; a merging portion 25; a detecting portion 30 that forms monitoring data DM indicating the intensity distribution of the monitoring light L3; and an analyzing portion 40. The optical image of the first monitoring light L31 is formed on the light incident surface 30a of the detecting unit 30 by the first lens 24 and the second lens 26. The second monitoring light L32 is condensed on the light incident surface 30a by the second lens 26. The analyzing portion 40 acquires a first measured value based on the first monitoring light L31 and a second measured value based on the second monitoring light L32 as measured values by analyzing one of the monitoring data DM.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[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, the laser light transmitted through a reflection mirror is split into reflected light and transmitted light by a beam splitter. The transmitted light is condensed onto a two-dimensional infrared sensor by a condenser lens and used for measuring the pointing state. On the other hand, the reflected light is transferred and imaged onto another two-dimensional infrared sensor by a transfer lens and used for measuring the beam profile.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a laser processing apparatus that irradiates a processing object with laser light, there is a possibility that processing defects may occur due to displacement of the emission position or emission angle over time or depending on the environment (such as ambient temperature, vibration, and shock) of the laser main body or the light guiding optical system, or due to a change in the divergence angle. In order to suppress such processing defects, it is necessary to acquire a plurality of measured values such as the beam profile and beam pointing of the laser light.

[0005] For this purpose, similar to the laser light source device described in Patent Document 1 mentioned above, it is conceivable to adopt a configuration in which laser light is branched into a plurality of lights, each light is made to enter an infrared sensor via a predetermined optical system, and a plurality of measured values of the laser light are acquired based on the detection results of the infrared sensor. However, in this case, software for analyzing the detection results of the optical system, the infrared sensor, and further each infrared sensor is required for the number of measured values to be acquired, resulting in complexity and high cost.

[0006] Therefore, an object of the present invention is to provide a laser processing apparatus capable of performing a plurality of measurements while suppressing complication and high cost of the apparatus.

Means for Solving the Problems

[0007] The laser processing apparatus according to the present invention 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 measured values from the monitor light. The monitor unit includes a first lens and a second lens disposed on the optical path of the monitor light, a second branching unit that polarization-separates the monitor light into first monitor light and second monitor light, a merging unit that merges the first monitor light and the second monitor light to form and emit the monitor light, a detection unit that forms monitor data indicating the intensity distribution of the monitor light by detecting the monitor light emitted from the merging unit, and an analysis unit that acquires a plurality of types of the measured values by performing a plurality of types of analyses on one piece of the monitor data. The first lens is disposed so that only the first monitor light among the monitor light passes through, the second lens is disposed 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, the second monitor light is condensed on the light incident surface by the second lens, and the analysis unit acquires, as the measured values, a first measured value based on the first monitor light and a second measured value based on the second monitor light by analyzing one piece of the monitor data."

[0008] In this laser processing apparatus, monitor light branched from the laser light is branched into first monitor light and second monitor light by a second branching unit. The first monitor light and the second monitor light are combined by a combining unit and are detected by a detection unit while constituting the monitor light again. At this time, the first monitor light is imaged on the light incident surface of the detection unit by a first lens and a second lens, and the second monitor light is condensed on the light incident surface of the detection unit by the second lens. That is, in the monitor light detected by the detection unit, the condensing state of the first monitor light and the condensing state of the second monitor light are made different. As a result, by analyzing one piece of monitor data formed by the detection unit, it becomes possible to acquire a plurality of 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. Thus, in this laser processing apparatus, while at least partially sharing an optical system (second lens) among a plurality of lights for obtaining a plurality of measurement values, the plurality of lights are combined and detected by one detection unit. Therefore, according to this laser processing apparatus, it is possible to perform a plurality of measurements while suppressing complication and high cost of the apparatus.

[0009] The laser processing apparatus according to the present invention may be the one described in [2] "The analysis unit acquires the beam diameter of the monitor light as the first measurement value by performing Gaussian fitting on the monitor data, in the laser processing apparatus according to [1] above". In this case, it is possible to detect a change in the beam diameter of the laser light.

[0010] The laser processing apparatus according to the present invention may be the one described in [3] "The analysis unit acquires the incident position of the monitor light on the light incident surface as the first measurement value by performing a centroid calculation on the monitor data, in the laser processing apparatus according to [1] or [2] above". In this case, it is possible to detect a change in the incident position of the laser light.

[0011] The laser processing apparatus according to the present invention may be "[4] the laser processing apparatus according to any one of [1] to [3] above, wherein the analysis unit obtains the maximum value of the intensity of the monitor light and the condensing 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, it is possible to detect a change in the emission angle of the laser light based on the condensing position of the monitor light, and it is possible to detect a change in the divergence angle of the laser light based on the maximum value of the intensity of the monitor light.

[0012] The laser processing apparatus according to the present invention may be "[5] the laser processing apparatus according to any one of [1] to [4] above, wherein the second lens is disposed in a subsequent stage of the confluence portion in the optical path of the monitor light". In this case, since the condensing diameter on the light incident surface can be reduced by shortening the optical path length from the light incident surface to the second lens, the incident position of the laser light can be measured with high resolution.

[0013] The laser processing apparatus according to the present invention may be "[6] the laser processing apparatus according to any one of [1] to [4] above, wherein the second lens is disposed in a preceding stage of the second branching portion in the optical path of the monitor light". In this case, since the condensing diameter on the light incident surface can be increased by lengthening the optical path length from the light incident surface to the second lens, damage to the detection unit can be suppressed.

[0014] The laser processing apparatus according to the present invention may be "[7] the laser processing apparatus according to any one of [1] to [6] above, wherein the monitor unit further includes a wavelength plate that adjusts a polarization component of the monitor light, and the wavelength plate is disposed in a preceding stage of the second branching portion in the optical path of the monitor light". In this case, by adjusting the polarization component of the monitor light in the wavelength plate, the light quantity ratio between the first monitor light and the second monitor light can be adjusted.

[0015] The laser processing apparatus according to the present invention may be the one described in "[8] 'The focal length of one of the first lens and the second lens that is disposed at a position far from the detection unit is equal to or less than the optical path length from the light source to the one lens, and the focal length of the other lens of the first lens and the second lens is equal to the optical path length from the other lens to the light incident surface, the laser processing apparatus according to any one of [1] to [7] above'. 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 detected more accurately.

[0016] The laser processing apparatus according to the present invention may be the one described in "[9] 'The focal length of the second lens is equal to the optical path length from the second lens to the light incident surface, the laser processing apparatus according to any one of [1] to [8] above'. In this case, changes in the optical axis angle of the laser light and changes in the divergence angle of the laser light can be detected more accurately.

[0017] The laser processing apparatus according to the present invention may be the one described in "

[10] '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 irradiated with the processing light, the laser processing apparatus according to any one of [1] to [9] above', or may be the one described in "

[11] 'The optical path length of the monitor light from the first branching unit to the light incident surface is 300 mm or less, the laser processing apparatus according to any one of [1] to

[10] above'. In these cases, changes in the monitor light caused by the optical system through which the monitor light passes in the monitor unit can be suppressed.

[0018] The laser processing apparatus according to the present invention may be the one described in "

[12] In the light incident surface, the condensing position of the second monitor light is located in a region within 50% of the distance from the beam center to the beam outer edge of the first monitor light, the laser processing apparatus according to any one of [1] to

[11] above". In this case, when performing Gaussian fitting on the monitor data, it is possible to suppress the second monitor light from becoming noise.

[0019] The laser processing apparatus according to the present invention may be the one described in "

[13] 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, the laser processing apparatus according to any one of [1] to

[12] above". 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.

Advantages of the Invention

[0020] According to the present invention, it is possible to provide a laser processing apparatus that can perform a plurality of measurements simultaneously while suppressing the price of the apparatus.

Brief Description of the Drawings

[0021]

Figure 1

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Figure 8

Figure 9

DETAILED DESCRIPTION OF THE INVENTION

[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 descriptions may be omitted.

[0023] FIG. 1 is a schematic diagram showing a laser processing apparatus according to the present 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 for performing laser processing on a processing object 10, such as a semiconductor wafer. More specifically, the laser processing apparatus 1 emits a laser beam L1 from the light source 2, generates a processing beam (laser beam) L2 by branching the laser beam L1 by the first branching unit 3, and condenses the processing beam L2 onto the processing surface 10a of the processing object 10 by the lens 4 to perform laser processing on the processing object 10. Hereinafter, each part will be specifically described.

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

[0025] The lens 4 is disposed on the optical path of the processed light L2 branched at the first branching portion 3. The lens 4 is, for example, an objective lens, and condenses the processed light L2 toward the processing surface 10a of the object to be processed 10. The mirrors 6 and 7 are arranged in this order between the light source 2 and the first branching portion 3 on the optical path of the laser beam L1. The mirrors 6 and 7 cause the laser beam L1 emitted from the light source 2 to be incident on the first branching portion 3 while sequentially reflecting it. Note that the laser processing apparatus 1 can be provided with a mechanism for adjusting the divergence angle of the laser beam L1, such as a collimator lens or a beam expander, between the light source 2 and the first branching portion 3.

[0026] The monitor unit 5 receives the monitor light (laser light) L3 branched at the first branching portion 3, and acquires a plurality of measurement values (for example, beam profile, beam pointing, and collimation state) of the laser beam L1 using the monitor light L3. The monitor unit 5 includes an optical system 20, a detection unit 30, and an analysis unit 40. The optical system 20 is for causing the monitor light L3 emitted from the first branching portion 3 to be incident on the light incident surface 30a of the detection unit 30.

[0027] The optical system 20 includes a mirror 21, a wavelength plate 22, a second branching portion 23, a first lens 24, a combining portion (wavelength multiplexing portion) 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 portion 3 into a first monitor light L31 and a second monitor light L32 by the second branching portion 23, combines the first monitor light L31 and the second monitor light L32 by the combining portion 25 to re-form the monitor light L3, and causes it to be incident on the light incident surface 30a of the detection unit 30. Subsequently, each part of the optical system 20 will be specifically described.

[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 portion 3 and the second branching portion 23. The mirror 21 reflects the monitor light L3 emitted from the first branching portion 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 portion 23. That is, the wave plate 22 is arranged in front of the second branching portion 23 on the optical path of the monitor light L3.

[0029] The second branching portion 23 is, for example, a polarization beam splitter, and splits the monitor light L3 emitted from the wave plate 22 into a first monitor light L31 and a second monitor light L32 by polarization separation. As an example, the second branching portion 23 transmits the p-polarization component of the monitor light L3 as the first monitor light L31 and reflects the s-polarization component of the monitor light L3 as the second monitor light L32, thereby branching the monitor light L3 into the first monitor light L31 and the second monitor light L32. The first monitor light L31 is used for measuring the first measurement value of the laser light L1, and the second monitor light L32 is used for measuring the 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 detection 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 quantity 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 detection unit 30. As an example, the light quantity ratio may be set such that the light quantity of the first monitor light L31 is about 80% of the light quantity of the monitor light L3, and the light quantity of the second monitor light L32 is about 20% of the light quantity of the monitor light L3. In this case, the wave plate 22 may be set to change the deflection direction of the monitor light L3 so that when the polarization component ratio of the monitor light L3 before passing through the wave plate 22 is 0% for the p-polarization component and 100% for the s-polarization component, the polarization component ratio of the monitor light L3 after passing through the wave plate 22 is 80% for the p-polarization component and 20% for the s-polarization component.

[0031] The first lens 24 and the second lens 26 are arranged on the optical path of the monitor light L3. More specifically, the first lens 24 is arranged between the second branching portion 23 and the confluence portion 25 on the optical path of the first monitor light L31. Therefore, the second monitor light L32 does not pass through the first lens 24. That is, the first lens 24 is arranged such that only the first monitor light L31 passes through. The focal length of the first lens 24 is less than or equal to the optical path length from the light source 2 to the first lens 24. Thereby, the front focal point of the first lens 24 is positioned between the light source 2 and the first lens 24.

[0032] The confluence portion 25 is, for example, a polarization beam splitter. By confluencing the first monitor light L31 and the second monitor light L32 that are polarization-separated at the second branching portion 23, the monitor light L3 is reconfigured and emitted. The monitor light L3 emitted from the confluence portion 25 passes through the second lens 26 and is incident on the light incident surface 30a of the detection unit 30.

[0033] The second lens 26 is arranged between the confluence portion 25 and the detection unit 30 on the optical path of the monitor light L3 emitted from the confluence portion 25. That is, the second lens 26 is arranged such that the monitor light L3 including the first monitor light L31 and the second monitor light L32 passes through. Also, in the present embodiment, among the first lens 24 and the second lens 26, the first lens 24 corresponds to one lens arranged at a position far from the detection unit 30 (light incident surface 30a), and the second lens 26 corresponds to the other lens. Note that the mirror 27a and the mirror 27b are sequentially arranged on the optical path of the second monitor light L32 so as to sequentially reflect the second monitor light L32 branched at the second branching portion 23 and make it incident on the confluence portion 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 at 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 light image of the first monitor light L31 (the light image at the front focal point of the first lens 24) is formed on the light incident surface 30a by the first lens 24 and the second lens 26, and the second monitor light L32 is condensed on the light incident surface 30a.

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

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

[0037] The detection unit 30 forms monitor data DM (see FIG. 2) indicating the intensity distribution of the monitor light L3 emitted from the confluence portion 25. The detection unit 30 is a sensor having a light incident surface 30a formed of, for example, pixels arranged in a two-dimensional manner. The detection unit 30 may include an image forming unit that forms a monitor image M described later from the monitor data DM, and the image forming unit may be integrally formed with the detection unit 30 or may be arranged as a separate body (such as a computer connected to the detection unit 30) from the detection unit 30. Further, the detection unit 30 may be an image sensor or the like.

[0038] Referring to FIGS. 2 and 3, the monitor data DM will be described. FIG. 2 is a display example of the monitor data DM and 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 shown by the shade of color. Further, in the monitor image M, the intensity distribution A1 in one cross section passing through a point of the monitor image M and the intensity distribution A2 in another cross section (a cross section orthogonal to the one cross section) passing through the same point of the image are superimposed. The reference point of the cross section is, for example, a point (pixel) corresponding to the condensing position P of the monitor light L3. The monitor image M shown in FIG. 2 corresponds to the sum of an image M1 which is a display example of comparison data showing the intensity distribution when only the first monitor light L31 shown in FIG. 3(a) is imaged and an image M2 which is a display example of comparison data showing the intensity distribution when only the second monitor light L32 shown in FIG. 3(b) is imaged.

[0039] The analysis unit 40 shown in FIG. 1 analyzes the monitor data DM formed by the detection unit 30. The analysis unit 40 is configured as a computer device including a processor, a memory, a storage, a communication device, and the like. In the analysis unit 40, software (program) read into the memory or the like is executed by the processor, and the reading and writing of data in the memory and the storage, as well as the communication by the communication device, are controlled by the processor. Thereby, the analysis unit 40 realizes various functions.

[0040] Hereinafter, the analysis unit 40 will be described 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 process 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 (the pixel of the light incident surface 30a). The vertical axis represents the intensity of the monitor light L3.

[0041] As shown in FIG. 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 centroid calculation unit 45. The analysis unit 40 acquires a plurality of types of measurement values by performing a plurality of types of analyses on one piece of monitor data DM indicating the intensity distribution of the monitor light L3. Specifically, the analysis unit 40 acquires, 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 by analyzing one piece of monitor data DM.

[0042] The data acquisition unit 41 acquires the monitor data DM formed by the detection unit 30. The data acquisition unit 41 outputs the monitor data DM to the maximum value position detection unit 42.

[0043] As shown in FIG. 5(a), the maximum value position detection unit 42 extracts the maximum value I1 of the intensity of the monitor light L3 from the intensity distribution A (the above-described intensity distribution A1 or intensity distribution A2) of the monitor data DM. Thereby, as the position where the maximum value I1 is obtained, the condensing position P (beam pointing) in the plane intersecting the optical axis of the monitor light L3 is acquired. Further, the maximum value position detection unit 42 acquires the collimation state of the laser light L1 based on the maximum value I1 of the intensity of the monitor light L3 and the characteristics of the optical system (for example, the second lens 26) for condensing the second monitor light L32 on the light incident surface 30a. As an example, based on the comparison between the maximum value (peak intensity) of the intensity of the monitor light L3 detected when the divergence angle of the laser light L1 is the reference value and the actually detected maximum value I1 (peak intensity) based on the characteristics of the second lens 26 and the like, the collimation state can be acquired.

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

[0045] First, as shown in FIG. 5(b), the fitting unit 43 performs Gaussian fitting on the intensity distribution A of the monitor data DM. Specifically, the fitting unit 43 creates an intensity distribution (approximate curve) F that approximates the intensity distribution A by fitting based on a Gaussian function to the intensity distribution A of the monitor data DM.

[0046] Next, the fitting unit 43 obtains the beam diameter of the monitor light L3 using the intensity distribution F. To do so, first, the fitting unit 43 detects the beam outer edge of the monitor light L3 (in the illustrated example, the position where the intensity becomes 1 / e of the maximum intensity I2 in the intensity distribution F) based on the intensity distribution F. Here, the positions of two points indicating the beam outer edge in the intensity distribution F are defined as position d1 and position d2, respectively. Then, the fitting unit 43 obtains the distance (position d2 - position d1) between the position d1 and the position d2 indicating the beam outer edge as the beam diameter of the monitor light L3. Note that the intensity distribution F is formed mainly by the part other than the peak due to the second monitor light L32 in the intensity distribution A being dominant. Therefore, the intensity distribution F is mainly formed 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 the first measurement value based on the first monitor light L31. 2 The binarization processing unit 44 obtains a binarized intensity distribution G by performing binarization on the intensity distribution A of the monitor data DM as shown by the dashed line in FIG. 5(c). Note that the binarization processing unit 44 may perform binarization based on the intensity distribution F. The binarization processing unit 44 outputs data indicating the binarized intensity distribution G to the centroid calculation unit 45.

[0047]

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

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

[0050] In the example of FIG. 6, the case where the condensing position P and the beam center C coincide is illustrated. However, the condensing position P and the beam center C may deviate within a certain range. The above-mentioned region R2 indicates the range of the deviation. That is, on the light incident surface 30a, the condensing position P only needs to be located in the region R2 within 50% of the distance from the beam center C to the beam outer edge.

[0051] Here, as described above, in the laser processing apparatus, due to time-dependent or environment-dependent factors (such as ambient temperature, vibration, shock, etc.) of the laser body and the light guiding optical system, deviations in the emission position and emission angle, and changes in the divergence angle may occur.

[0052] The deviation of the emission position of the laser beam shifts the optical axis of the laser beam incident on the objective lens (optical axis shift). When the optical axis incident on the objective lens shifts (i.e., when the incident position on the objective lens changes), the condensing pattern collapses on the processing surface. Such an optical axis shift can be confirmed by detecting the position of the laser beam based on the beam profile of the laser beam. That is, 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 the beam profile of the laser beam when an optical axis shift occurs by each value from 0.25 to 1.0. In the laser processing apparatus 1 according to the present embodiment, the monitor unit 5 acquires the beam center C based on the intensity distribution (beam profile) of the monitor light L3. Therefore, based on this beam center C, it is possible to confirm the optical axis shift.

[0053] Also, the deviation of the emission angle of the laser beam (angle deviation) inclines the optical axis incident on the objective lens. When the optical axis incident on the objective lens inclines, as shown in FIG. 8(a), the position of the condensing pattern of the laser beam shifts with respect to the principal axis of the objective lens on the processing surface. Each graph in FIG. 8(a) shows the condensing pattern of the laser beam when no inclination of the optical axis occurs (reference (no inclination)), and the condensing pattern of the laser beam when an inclination of the optical axis occurs by each value from 0.2° to 1.0°. Such an angle deviation can be confirmed by detecting the optical axis angle (inclination angle) by beam pointing of the laser beam. In the laser processing apparatus 1 according to the present embodiment, the monitor unit 5 acquires the condensing position P (beam pointing) of the monitor light L3. Therefore, based on this condensing position P, it is possible to detect the optical axis angle and confirm the angle deviation.

[0054] Furthermore, the change in the divergence angle of the laser beam changes the focusing position of the laser beam in the direction of the optical axis of the laser beam. In other words, when the divergence angle of the laser beam changes, as a result, the focusing position changes in the direction of the optical axis of the laser beam, and as shown in FIG. 8(b), the peak intensity of the laser beam changes (decreases). Each graph in FIG. 8(b) shows the peak intensity of the laser beam when the divergence angle is 0.1 mrad (reference) and 0.5 mrad. Therefore, the change in the divergence angle can be confirmed by detecting the collimation state of the laser beam (i.e., the change in the peak intensity). In the laser processing apparatus 1 according to the present embodiment, the monitor unit 5 acquires the collimation state of the laser beam L1 based on the maximum value I1 of the intensity of the monitor light L3. Therefore, based on this collimation state, it is possible to confirm the change in the divergence angle of the laser beam L1.

[0055] Conventionally, in order to acquire the collimation state of the laser beam, it has been necessary to move a detection unit such as a camera along the optical axis of the laser beam. On the other hand, in the laser processing apparatus 1, since the collimation state of the laser beam L1 can be acquired based on the maximum value I1 of the intensity of the monitor light L3, it is not necessary to move the detection unit 30. [Operation and Effect]

[0056] As described above, in the laser processing apparatus 1, the monitor light L3 branched from the laser light L1 is branched into a first monitor light L31 and a second monitor light L32 by the second branching unit 23. The first monitor light L31 and the second monitor light L32 are combined by the combining unit 25 and detected by the detection unit 30 while forming the monitor light L3 again. At this time, the first monitor light L31 is imaged on the light incident surface 30a of the detection 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 of the detection unit 30 by the second lens 26. That is, in the monitor light L3 detected by the detection unit 30, the condensing state of the first monitor light L31 and the condensing 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, a plurality of 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, condensing position P) based on the second monitor light L32 can be obtained. Thus, in this laser processing apparatus 1, while at least partially sharing the optical system (second lens 26) among a plurality of lights for obtaining a plurality of measurement values, the plurality of lights are combined and detected by one detection unit 30. Therefore, according to this laser processing apparatus 1, it is possible to perform a plurality of measurements while suppressing the complication and high cost of the apparatus. Since the complication of the apparatus can be suppressed, it is also possible to reduce the apparatus size.

[0057] Further, in the laser processing apparatus 1, by monitoring each parameter of the first measurement value and the second measurement value, each parameter during processing can be recorded. Furthermore, it is possible to detect a shift or inclination of the processing optical axis and a change in the beam diameter during processing, and it becomes possible to provide a stable processing process.

[0058] As described above, the monitor light L3 is polarization-separated into the first monitor light L31 and the second monitor light L32 in the second branching unit 23. Therefore, since the polarization components of the first monitor light L31 and the second monitor light L32 are different, even if both monitor lights are incident on one detection unit 30 at the same time, interference between the two monitor lights can be suppressed.

[0059] The fitting part 43 of the analysis part 40 performs Gaussian fitting on the intensity distribution F of the monitor data DM, thereby obtaining the beam diameter of the monitor light L3 as the first measurement value. Thereby, the change in the beam diameter of the laser beam L1 can be detected.

[0060] The centroid calculation part 45 performs centroid calculation on the binarized intensity distribution G output from the binarization processing part 44, thereby obtaining the beam center C on the light incident surface 30a of the monitor light L3 as the first measurement value. Thereby, the change in the incident position of the laser beam L1 with respect to the objective lens (that is, the optical axis shift) can be detected.

[0061] The maximum value position detection part 42 extracts the maximum value I1 of the intensity of the monitor light L3 from the intensity distribution A of the monitor data DM, thereby obtaining the maximum value I1 of the intensity of the monitor light L3 and the condensing position P on the light incident surface 30a as the second measurement value based on the second monitor light L32. Thereby, based on the condensing position P, it is possible to detect the inclination (angle deviation) of the optical axis incident on the lens 4 due to the deviation of the emission angle of the laser beam L1, and based on the maximum value I1, it is possible to detect the change in the divergence angle of the laser beam L1.

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

[0063] The second lens 26 is disposed between the confluence part 25 and the detection part 30 on the third optical path of the monitor light L3. That is, the second lens 26 is disposed at the subsequent stage of the confluence part 25 in the optical path of the monitor light L3. Thereby, by shortening the optical path length from the light incident surface 30a to the second lens 26, the condensing diameter on the light incident surface 30a can be reduced. Therefore, the incident position of the laser beam can be measured with high resolution.

[0064] The wavelength plate 22 is disposed in front of the second branching portion 23 in the optical path of the monitor light L3. Thereby, by adjusting the polarization component of the monitor light L3 in the wavelength plate 22, the light quantity ratio of the first monitor light L31 and the second monitor light L32 branched in the second branching portion 23 can be adjusted. Further, as described above, by adjusting the light quantity ratio in the wavelength plate 22, it is possible to suppress the occurrence of crosstalk 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 lens 24 and the second lens 26 disposed at a position far from the detection unit 30 (the first lens 24 in the present embodiment) is equal to or less than the optical path length from the light source 2 to the one lens, and the focal length of the other lens of the first lens 24 and the second lens 26 (the second lens 26 in the present embodiment) is equal to the optical path length from the other lens to the light incident surface 30a. Thereby, in the present embodiment, since 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, the laser beam L1 can be more accurately imaged on the light incident surface 30a. Therefore, changes in the beam diameter and the incident position of the laser beam L1 can be detected more accurately.

[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 30a. Thereby, the rear focal point of the second lens 26 is positioned on the light incident surface 30a. Therefore, changes in the optical axis angle of the laser beam and changes in the divergence angle of the laser beam can be detected more accurately.

[0067] The optical path length of the monitor light L3 from the first branch portion 3 to the light incident surface 30a is, for example, 300 mm or less, and is shorter than the optical path length of the processing light L2 from the first branch portion 3 to the processing surface 10a irradiated with the processing light L2. Thereby, changes in the monitor light L3 due to the optical system 20 through which the monitor light L3 of the monitor unit 5 passes can be suppressed.

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

[0069] 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. Thereby, 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 optical image of the first monitor light L31 (the optical image at the front focal point of the first lens 24) is formed on the light incident surface 30a by the first lens 24 and the second lens 26, and the second monitor light L32 is condensed on the light incident surface 30a. Therefore, changes in the optical axis of the monitor light L3 due to the optical system 20 of the monitor unit 5 through which the monitor light L3 passes can be suppressed. [Modification Example]

[0070] The above embodiments illustrate one aspect of the present invention. Therefore, the present invention is not limited to the laser processing apparatus 1 described above and can be arbitrarily modified.

[0071] FIG. 9 is a schematic diagram showing a laser processing apparatus according to a modification example. The laser processing apparatus 1A shown in FIG. 9 is different from the laser processing apparatus 1 according to the above embodiment in that the second lens 26 is disposed in front of the second branch portion 23 in the optical path of the monitor light L3. Specifically, in the laser processing apparatus 1A, the second lens 26 is disposed between the wavelength plate 22 and the second branch portion 23 on the optical path of the monitor light L3.

[0072] That is, in the example of FIG. 9, among the first lens 24 and the second lens 26, the second lens 26 corresponds to one lens disposed at a position far from the detection unit 30 (light incident surface 30a), 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 less 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 30a. 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 30a. In this case, since the second lens 26 has a function of condensing the second monitor light L32 onto the light incident surface 30a, the optical path length from the second lens 26 to the light incident surface 30a is the optical path length including the optical path of the second monitor light L32 via the mirrors 27a and 27b.

[0073] According to the example of FIG. 9 as described above, since the optical path length from the light incident surface 30a to the second lens 26 can be increased, the condensing diameter of the monitor light L3 on the light incident surface 30a can be increased. Thereby, damage to the detection unit 30 can be suppressed.

[0074] Note that, in the above-described embodiment and the example of FIG. 9, the focal length of one lens disposed at a position far from the detection unit 30 among the first lens 24 and the second lens 26 may not be equal to or less than the optical path length from the light source 2 to the one lens, and the focal length of the other lens among the first lens 24 and the second lens 26 may not be equal to the optical path length from the other lens to the light incident surface 30a. Also, the focal length of the second lens 26 may not be equal to the optical path length from the second lens 26 to the light incident surface 30a. Further, the optical path length between the first lens 24 and the second lens 26 may not be equal to the sum of the focal length of the first lens 24 and the focal length of the second lens 26.

[0075] The present invention is not limited to the above-described embodiment and modified examples. The materials and shapes of each component are not limited to the materials and shapes described above, and various materials and shapes can be adopted.

[0076] For example, the polarization component ratio of the monitor light L3 after passing through the waveplate 22 is not limited to the ratio of the above embodiment. For example, by adjusting the waveplate 22 to change the polarization component ratio of the monitor light L3, only the first monitor light L31 can be imaged on the detection unit 30. Similarly, by adjusting the waveplate 22, only the second monitor light L32 can be condensed on the detection unit 30. Thereby, it is possible to optically switch to obtain only the first measurement value or only the second measurement value.

[0077] In addition, in the above embodiment, the case where the monitor unit 5 obtains the beam diameter of the monitor light L3 by performing Gaussian fitting on the monitor data DM is exemplified. However, the monitor unit 5 may obtain the beam diameter of the monitor light L3 by any other method.

[0078] In addition, in the above embodiment, the case where the monitor unit 5 obtains the beam center C by performing a centroid operation on the intensity distribution G obtained by binarizing the intensity distribution A (or intensity distribution F) of the monitor light L3 is exemplified. However, the monitor unit 5 is not limited to the binarized intensity distribution G, and may obtain the beam center C based on the centroid operation of any intensity distribution (for example, intensity distribution A or intensity distribution F) obtained from the monitor data DM. Furthermore, the monitor unit 5 may obtain the beam center C by other methods instead of the centroid operation.

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

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

Explanation of reference numerals

[0081] 1,1A... Laser processing apparatus, 2... Light source, 3... First branching section, 5... Monitor section, 10a... Processing surface, 22... Wavelength 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 (incidence 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... Focus position, R2... Region.

Claims

1. A light source that emits a laser beam, A first branching unit that branches the laser beam emitted from the light source into a processing beam and a monitor beam, A monitor unit that acquires a plurality of measurement values from the monitor beam, Comprising: The monitor unit A first lens and a second lens disposed on the optical path of the monitor beam, A second branching unit that polarization-separates the monitor beam into a first monitor beam and a second monitor beam, A merging unit that merges the first monitor beam and the second monitor beam to form and emit the monitor beam, A detection unit that forms monitor data indicating the intensity distribution of the monitor beam by detecting the monitor beam emitted from the merging unit, An analysis unit that acquires a plurality of types of the measurement values by performing a plurality of types of analyses on one piece of the monitor data, Having: The first lens is disposed so that only the first monitor beam among the monitor beams passes therethrough, The second lens is disposed so that the monitor beam including the first monitor beam and the second monitor beam passes therethrough, The first monitor beam is imaged on the light incident surface of the detection unit by the first lens and the second lens, The second monitor beam is condensed on the light incident surface by the second lens, The analysis unit acquires, as the measurement values, a first measurement value based on the first monitor beam and a second measurement value based on the second monitor beam by analyzing one piece of the monitor data, A laser processing apparatus.

2. The analysis unit acquires the beam diameter of the monitor beam as the first measurement value by performing Gaussian fitting on the monitor data, The laser processing apparatus according to Claim 1.

3. The analysis unit acquires the incident position of the monitor beam on the light incident surface as the first measurement value by performing a centroid calculation on the monitor data, The laser processing apparatus according to Claim 1.

4. The analysis unit extracts the maximum value of the intensity of the monitor beam in the monitor data to acquire the maximum value of the intensity of the monitor beam and the condensing position as the second measurement value, The laser processing apparatus according to Claim 1.

5. The second lens is disposed at a subsequent stage of the merging unit in the optical path of the monitor beam, The laser processing apparatus according to Claim 1.

6. The second lens is disposed at a preceding stage of the second branching unit in the optical path of the monitor beam, The laser processing apparatus according to Claim 1.

7. The monitor unit further includes a wavelength plate that adjusts the polarization component of the monitor light. The wavelength plate is disposed in front of the second branching portion in the optical path of the monitor light. The laser processing apparatus according to claim 1.

8. The focal length of one of the first lens and the second lens that is disposed at a position far from the detection unit is equal to or less than the optical path length from the light source to the one lens. The focal length of the other lens of the first lens and the second lens is equal to the optical path length from the other lens to the light incident surface. The laser processing apparatus according to claim 1.

9. The focal length of the second lens is equal to the optical path length from the second lens to the light incident surface. The laser processing apparatus according to claim 1.

10. 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 irradiated with the processing light. The laser processing apparatus according to claim 1.

11. The optical path length of the monitor light from the first branching portion to the light incident surface is 300 mm or less. The laser processing apparatus according to claim 1.

12. At the light incident surface, the condensing position of the second monitor light is located in a region within 50% of the distance from the beam center to the beam outer edge of the first monitor light. The laser processing apparatus according to claim 1.

13. 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. The laser processing apparatus according to claim 1.

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