Processing state monitoring device, method, program, and recording medium

Abstract

This processing state monitoring device, which monitors a processing state caused by laser processing, comprises: a first sensor that detects first radiation light from a processing part of a processing object that receives laser light emitted from a laser oscillator via a processing optical element, and acquires first temperature information pertaining to the temperature of the processing part on the basis of the first radiation light; and a second sensor that detects second radiation light from the processing optical element and acquires second temperature information pertaining to the temperature of the processing optical element on the basis of the second radiation light.

Description

Machining state monitoring device, method, program, and recording medium

[0001] The present disclosure relates to a machining state monitoring device, method, program, and recording medium.

[0002] Monitoring the processing state during laser processing has been studied. The temperature of the processing part may be used to determine the processing state. For example, Patent Document 1 discloses a laser processing device equipped with a data processing unit that determines the beam profile of laser light passing through a target from the temperature distribution of the target measured by a radiation thermometer.

[0003] JP 2015-166094 A

[0004] The laser processing device described in Patent Document 1 still has room for improvement in terms of improving the accuracy of temperature measurement of the processing portion during laser processing.

[0005] The present disclosure provides a processing state monitoring device, method, program, and recording medium that improve the accuracy of temperature measurement of a processing portion in laser processing.

[0006] A processing state monitoring device according to one aspect of the present disclosure is a device for monitoring a processing state by laser processing, and includes: a first sensor that detects first radiation light from a processing portion of a workpiece that receives laser light emitted from a laser oscillator via a processing optical element, and acquires first temperature information related to the temperature of the processing portion based on the first radiation light; and a second sensor that detects second radiation light from the processing optical element, and acquires second temperature information related to the temperature of the processing optical element based on the second radiation light.

[0007] A control method for a processing state monitoring device according to one aspect of the present disclosure includes: acquiring first temperature information from a first sensor that detects first radiation light from a processing portion of a workpiece that receives laser light emitted from a laser oscillator via a processing optical element and acquires first temperature information related to the temperature of the processing portion based on the first radiation light; acquiring second temperature information from a second sensor that detects second radiation light from the processing optical element and acquires second temperature information related to the temperature of the processing optical element; controlling a position of a first lens that focuses the first radiation light on the first sensor based on the second temperature information; and determining a processing state of laser processing based on the first temperature information after controlling the position of the first lens.

[0008] A program according to one aspect of the present disclosure causes a computer to execute the above-described method.

[0009] A computer-readable recording medium according to one aspect of the present disclosure causes a computer to execute the above-described method.

[0010] According to the present disclosure, it is possible to provide a processing state monitoring device, method, program, and recording medium that improve the accuracy of temperature measurement of a processing portion in laser processing.

[0011] Graph showing the relationship between wavelength and radiant energy density according to Planck's law; Graph showing wavelengths showing maximum radiant energy densities at each temperature; Schematic diagram for explaining the relationship between the measurement position, the pinhole, and the second sensor; Schematic diagram showing a state where the measurement position of FIG. 3A is shifted; Graph showing the relationship between the detected light intensity of the second sensor and the shift in the measurement position of the second radiant light; Schematic diagram showing the state of the laser beam and the first radiant light when no thermal lens effect occurs; Schematic diagram showing the state of the laser beam and the first radiant light when thermal lens effect occurs; Schematic diagram for explaining adjustment of the position of the first lens when thermal lens effect occurs; Flowchart for explaining control of the processing state monitoring device 100; Schematic diagram showing the processing state monitoring device according to a first modification of the first embodiment; Schematic diagram showing the processing state monitoring device according to a second embodiment.

[0012] (Background to the present disclosure) Laser processing technology is known in which a workpiece is irradiated with laser light to melt or vaporize the surface of the workpiece to weld it to another workpiece, or to melt or vaporize a portion of the workpiece to change its shape. Laser processing technology is generally widespread in a wide range of fields, such as home appliances, precision instruments, and automotive parts. When processing using laser processing technology, the laser processing state is monitored to achieve stable processing.

[0013] One method for monitoring the laser processing state is to measure the temperature of the processing area. By measuring the temperature of the processing area, the processing state by laser processing can be grasped.

[0014] For example, Patent Document 1 discloses a laser processing device that includes a laser light source, a beam splitter, first and second mirrors, first and second galvanometer scanning mechanisms, an fθ lens, an imaging lens, a radiation thermometer, a data processing unit, and a beam profile and control unit.

[0015] In recent years, fiber lasers have been increasingly used in laser processing using high-power lasers for welding, cutting, etc. When a high-power laser is used, the processing optical system is heated by the high-power laser, and therefore the laser processing device described in Patent Document 1 has a problem in that it is not possible to grasp the temperature of the processing area with high accuracy.

[0016] Therefore, the present inventors have studied ways to improve the accuracy of temperature measurement of a processed portion in laser processing, and have arrived at the following invention.

[0017] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In each drawing, elements are exaggerated for ease of explanation.

[0018] As used herein, terms such as "first," "second," etc. are used for descriptive purposes only and should not be understood as expressing or implying relative importance or ranking of technical features. Features qualified as "first" and "second" expressly or imply the inclusion of one or more of that feature.

[0019] First Embodiment [Overall Configuration] FIG. 1 is a schematic diagram illustrating a machining state monitoring device 100 according to a first embodiment.

[0020] The processing state monitoring device 100 according to this embodiment is a device for monitoring the processing state by laser processing. In this embodiment, the processing state by laser processing is monitored using information about the temperature of the processing portion 6 when the laser light L1 emitted from the laser oscillator 1 is reflected by the first mirror 2 and irradiated onto the processing portion 6 of the workpiece 4 via the processing optical element 3.

[0021] First, with reference to FIG. 1, a laser oscillator 1, a first mirror 2, and an optical element for processing 3 will be described.

[0022] The laser oscillator 1 is configured by, for example, a fiber laser. In this embodiment, for example, the laser oscillator 1 outputs a continuous wave (CW) laser beam having a wavelength of 1.07 μm. The laser beam L1 is intended for use in laser welding and is emitted with a maximum output of 3 kW. The laser beam L1 emitted by the laser oscillator 1 is collimated by a collimating optical system (not shown) so that the laser beam propagates to the processing portion 6.

[0023] The laser beam L1 emitted by the laser oscillator 1 is reflected by the first mirror 2 toward the processing optical element 3. The first mirror 2 is positioned, for example, at a 45-degree angle with respect to the optical axis O1 of the laser beam L1 emitted from the laser oscillator 1 to propagate the laser beam L1 to the processing position. The first mirror 2 has a coating that reflects the laser beam L1 with a wavelength of 1.07 μm and transmits the radiation M1 from the processing portion 6. The radiation M1 from the processing portion 6 has a wide wavelength range, including the visible and near-infrared regions. Therefore, the first mirror 2 transmits 10% or more of light with at least some wavelengths in the wavelength range of 0.35 μm to 10 μm, excluding the 1.07 μm wavelength of the laser beam L1. The first mirror 2 also reflects 90% or more of the light with a wavelength of 1.07 μm of the laser beam L1. The transmission wavelength range, reflection wavelength range, reflectance, and transmittance of the first mirror 2 are not limited to the values ​​described above.

[0024] The processing optical element 3 includes at least one of a lens or a mirror. In the present embodiment, the processing optical element 3 is configured as a condenser lens. The processing optical element 3 condenses the laser light L1 reflected by the first mirror 2 onto a processing portion 6 of the workpiece 4. The processing portion 6 is a portion of the surface of the workpiece 4 where welding is performed by the laser light L1. In the present embodiment, the processing optical element 3 also has the function of transmitting and collimating the light radiated from the processing portion 6. The processing optical element 3 is configured of a material that transmits the first radiated light M1. More specifically, the processing optical element 3 has a focal length f3 of 250 mm, for example, and is configured to transmit at least 50% of light with a wavelength of 1.07 μm and at least 10% of light with a wavelength of 0.35 μm to 10 μm.

[0025] The workpiece 4 to be machined with the laser beam L1 is supported on a machining stage 5, which is composed of, for example, an XYZθ table and a fixture for fixing the workpiece 4. The machining stage 5 is controlled so that the irradiation position of the laser beam L1 on the workpiece 4 can be moved. The movement of the irradiation position of the laser beam L1 can be achieved, for example, by moving the machining stage 5 while the irradiation position of the laser beam L1 is fixed. Alternatively, the irradiation position of the laser beam L1 can be moved by changing the irradiation angle of the laser beam L1 using a mirror or the like and then focusing the laser beam L1 at the irradiation position using a focusing lens. Alternatively, the irradiation position of the laser beam L1 can be moved by installing an optical scanner such as a galvanometer mirror. Furthermore, the irradiation position of the laser beam L1 can be moved by combining the above methods.

[0026] The machining state monitoring device 100 monitors the machining state when the work-piece 4 is machined with the laser light L1. The machining state monitoring device 100 will be described below.

[0027] As shown in Fig. 1, the machining state monitoring device 100 includes a first sensor 10 and a second sensor 13. The first sensor 10 detects a first radiation M1 from a machining portion 6 of a workpiece 4 and acquires first temperature information related to the temperature of the machining portion 6 based on the first radiation M1. The machining portion 6 is a part of the workpiece 4 and receives a laser beam L1 emitted from the laser oscillator 1 via a machining optical element 3. The second sensor 13 detects a second radiation M2 from the machining optical element 3 and acquires second temperature information related to the temperature of the machining optical element 3 based on the second radiation M2.

[0028] The processing state monitoring device 100 is disposed on the opposite side of the first mirror 2 from the workpiece 4. In this embodiment, the processing state monitoring device 100 has a filter 7, a spectral mirror 8, a first lens 9, a second lens 11, and a pinhole 12.

[0029] The first lens 9 is a lens that focuses the first radiation light M1 on the first sensor 10. The second lens 11 is a lens that focuses the second radiation light M2 on the second sensor 13. The filter 7 is a filter that blocks reflected light of the laser light L1. The spectroscopic mirror 8 is a mirror that reflects light of a predetermined wavelength and transmits light of other wavelengths. The pinhole 12 is an optical element that has a hole that passes the second radiation light M2. Note that these components are not essential components of the processing state monitoring device 100.

[0030] The processing state monitoring device 100 further includes a control unit 15 that controls the first lens 9. Note that the control unit 15 is not an essential component of the processing state monitoring device 100.

[0031] The first sensor 10 and the second sensor 13 are configured, for example, by photodetectors. In this embodiment, sensors sensitive to light with wavelengths of 0.35 μm or more and 10 μm or less are used as the first sensor 10 and the second sensor 13. The first sensor 10 may be a sensor with a single detector surface, or may be a camera-type sensor configured with multiple pixels.

[0032] 1, a first radiation beam M1 and a second radiation beam M2 are emitted from the processing portion 6. A first sensor 10 detects the first radiation beam M1, and a second sensor 13 detects the second radiation beam M2.

[0033] The first radiation light M1 includes reflected light and radiation light from the processing portion 6. The first radiation light M1 includes, for example, light of 0.35 μm or more and 10 μm or less, which includes the wavelength range of infrared light. When the laser light L1 is irradiated onto the workpiece 4, a processing phenomenon such as welding or cutting occurs at the processing portion 6. The first radiation light M1 includes reflected light that is reflected when the laser light L1 is irradiated onto the workpiece 4, and light emitted by an interaction between the workpiece 4 and the laser light L1. Examples of light emitted by an interaction include plasma light emitted when the workpiece 4 is evaporated by the laser light L1 and turned into plasma, and thermal radiation light emitted when the workpiece 4 is heated and melted.

[0034] The second radiated light M2 includes radiated light from the processing optical element 3. The radiated light from the processing optical element 3 is radiated light from a measurement position 14 that is virtually set at an arbitrary position inside the processing optical element 3. The second radiated light M2 includes, for example, thermal radiation light that is emitted when the processing optical element 3 is heated by the power absorbed by the processing optical element 3 when the laser beam L1 passes through the processing optical element 3. The second radiated light M2 includes light in at least a wavelength range of 0.35 μm or more and 10 μm or less.

[0035] The first sensor 10 detects the first radiation M1 and acquires first temperature information regarding the temperature of the processing portion 6. The first temperature information can be acquired, for example, by converting the first radiation M1 into electricity by photoelectric conversion and based on the intensity of the resulting voltage.

[0036] FIG. 2A is a graph showing the relationship between wavelength and radiant energy density according to Planck's law. FIG. 2B is a graph showing the wavelength at which the radiant energy density is maximum at each temperature. The first sensor 10 detects the first radiant light M1 from the processing unit 6. The processing unit 6 performs laser welding or laser cutting of a workpiece 4 made of, for example, aluminum, copper, or iron. For example, if the workpiece 4 is made of aluminum, the temperature of the processing unit 6 will be approximately 933 K (approximately 660°C), which is the melting point of aluminum. Similarly, if the workpiece 4 is made of copper or iron, the temperatures of the processing unit 6 will be approximately 1353 K (approximately 1080°C) and 1773 K (approximately 1500°C). Referring to FIGS. 2A and 2B, for example, the radiant energy density at 933 K, the melting point of aluminum, is maximum at a wavelength of 3.07 μm. Similarly, the radiant energy density at 1353 K, the melting point of copper, is maximum at a wavelength of 2.11 μm, and the radiant energy density at 1773 K, the melting point of iron, is maximum at a wavelength of 1.61 μm. For this reason, it is preferable that the first sensor 10 be able to detect light with a wavelength of 0.35 μm or more and less than 6.0 μm.

[0037] The second sensor 13 detects the second radiation M2 and acquires second temperature information regarding the temperature of the optical processing element 3. The second temperature information can be acquired, for example, by converting the second radiation M2 into electricity by photoelectric conversion and based on the intensity of the resulting voltage.

[0038] During processing, the processing optical element 3 is heated by the laser light L1, causing the temperature of the processing optical element 3 to rise. If the temperature of the processing optical element 3 rises too much, cracks or the like may occur in the processing optical element 3. Therefore, the temperature rise of the processing optical element 3 is considered to be in the range of approximately 100°C to 200°C (373K to 473K). As shown in Figures 2A and 2B, the radiant energy density at 473K is maximum at a wavelength of 6.07 μm, and the radiant energy density at 373K is maximum at a wavelength of 7.72 μm. For this reason, it is preferable that the second sensor 13 be able to detect light with a wavelength of 6 μm or more.

[0039] In this embodiment, the predetermined branch wavelength is set to 6 μm, and the light is branched by the spectral mirror 8 into a first radiation M1 that is less than the predetermined branch wavelength and a second radiation M2 that is equal to or greater than the predetermined branch wavelength. That is, the spectral mirror 8 functions as a first branching element that branches the radiation including the first radiation M1 and the second radiation M2 into the first radiation M1 that is less than the predetermined branch wavelength and the second radiation M2 that is equal to or greater than the predetermined branch wavelength. The predetermined branch wavelength can be, for example, 5 μm or more and 10 μm or less.

[0040] The spectral mirror 8 is an optical element that reflects light having a wavelength equal to or greater than a predetermined branch wavelength and transmits light having a wavelength less than the predetermined branch wavelength. In this embodiment, the predetermined branch wavelength is 6.0 μm, so that the first radiation M1 having a wavelength less than 6.0 μm passes through the spectral mirror 8 and reaches the first sensor 10, and the second radiation M2 having a wavelength equal to or greater than 6.0 μm is reflected by the spectral mirror 8 and reaches the second sensor 13.

[0041] In this embodiment, the first radiation M1 transmitted through the spectral mirror 8 passes through the first lens 9 and reaches the first sensor 10. The first radiation M1 passes through the processing optical element 3 from the processing unit 6 and is collimated. The first mirror 2 then reflects the 1.07 μm wavelength laser light L1 contained in the first radiation M1. Furthermore, a filter 7 disposed between the first mirror 2 and the spectral mirror 8 blocks the 1.07 μm wavelength laser light L1 contained in the first radiation M1. The filter 7 may be a notch filter that blocks the wavelength of the laser light L1. The filter 7 preferably has an optical density (OD) in the range of 4 to 6 so that the laser light L1 reflected by the processing unit 6 does not enter the processing state monitoring device 100. Note that, for example, when the workpiece 4 is a highly reflective material such as copper, the use of the filter 7 is preferable because the intensity of the reflected light is high. On the other hand, if the workpiece 4 is a material with low reflectivity, the reflected light can be sufficiently attenuated by the first mirror 2, so the filter 7 does not need to be provided. Also, the optical density of the filter 7 may be adjusted according to the intensity of the reflected light.

[0042] The first mirror 2 and the filter 7 attenuate the light with a wavelength of 1.07 μm contained in the first radiation M1 before it reaches the spectral mirror 8. The first radiation M1 passes through the spectral mirror 8 and is imaged by the first sensor 10. The first lens 9 is disposed between the spectral mirror 8 and the first sensor 10 so that the first sensor 10 and the processing unit 6 have a conjugate relationship.

[0043] The diameter of the imaging spot of the first radiation M1 on the first sensor 10 is preferably smaller than the detector surface size or pixel size of the first sensor 10 .

[0044] Because the first sensor 10 and the processing unit 6 are in a conjugate relationship, the spot diameter d1 of the first synchrotron radiation M1 is determined by the size of the processing area in the processing unit 6. The size of the processing area in the processing unit 6 refers to the size of the area in the processing unit 6 that emits the first synchrotron radiation M1. If the ratio of the spot diameter d1 of the first synchrotron radiation M1 in the first sensor 10 to the size of the processing area is taken as m1, then the ratio m1 can be expressed by the following formula A using the focal length f1 of the first lens 9 and the focal length f3 of the processing optical element 3.

[0045] m1 = f1 / f3 (Equation A) For example, if the focal length f3 of the processing optical element 3 is 250 mm and the focal length f1 of the first lens 9 is 25 mm, the ratio m1 is m1 = 25 / 250 = 0.1. In this case, if the size of the processing area in the processing unit 6 is 1.0 mm, the spot diameter d1 of the first radiation M1 on the first sensor 10 is d1 = 1.0 × 0.1 = 0.1 mm. Therefore, under the above conditions, it is preferable that the detector surface size or pixel size of the first sensor 10 be larger than 0.1 mm. The detector surface size or pixel size of the first sensor 10 should be selected to an appropriate size depending on the focal lengths of the processing optical element 3 and the first lens 9.

[0046] The second radiation light M2 reflected by the spectral mirror 8 is collected by the second lens 11 disposed between the spectral mirror 8 and the second sensor 13, and reaches the second sensor 13. The second radiation light M2 is radiation from the processing optical element 3. As described above, the temperature of the processing optical element 3 is lower than that of the processing portion 6, and therefore, light having a longer wavelength than the first radiation light M1 reaches the second sensor 13.

[0047] Between the second lens 11 and the second sensor 13, the pinhole 12 is arranged at a position that is conjugate with a measurement position 14 that is virtually set in the processing optical element 3. The pinhole 12 is arranged so that the hole of the pinhole 12 is conjugate with the measurement position 14.

[0048] Fig. 3A is a schematic diagram illustrating the relationship between the measurement position 14 and the pinhole 12 and the second sensor 13. Fig. 3B is a schematic diagram illustrating a state in which the measurement position 14 in Fig. 3A is shifted. Fig. 3C is a graph showing the relationship between the detected light intensity P of the second sensor 13 and the shift in the measurement position of the second radiation light M2.

[0049] 3A shows a state in which the second radiation light M2 from the measurement position 14 is imaged on the hole of the pinhole 12. The state in which the second radiation light M2 from the measurement position 14 is imaged on the hole of the pinhole 12 is defined as a state in which the displacement Z of the measurement position 14 is 0.

[0050] The relationship expressed by Equation B holds between the focal length f2 of the second lens 11, the optical distance S1 between the measurement position 14 and the second lens 11, and the optical distance S2 between the second lens 11 and the pinhole 12, which is the imaging position.

[0051] 1 / S1+1 / S2=1 / f2 (Equation B) When the processing optical element 3 is heated by the laser light L1, a positional shift of the measurement position 14 occurs, for example, due to the thermal lens effect described below. The example of Fig. 3B shows a state in which the shift Z of the measurement position 14 is Z1. That is, the example of Fig. 3B shows a state in which the optical distance between the measurement position 14 and the second lens 11 is S1-Z1. That is, in the example of Fig. 3B, the optical distance between the measurement position 14 and the second lens 11 is shorter than in the case of Fig. 3A.

[0052] According to Equation B, as the optical distance between the measurement position 14 and the second lens 11 decreases, the distance between the second lens 11 and the image position of the second radiation light M2 from the measurement position 14 increases. Therefore, when the measurement position 14 is misaligned, the image position of the second radiation light M2 from the measurement position 14 is located closer to the sensor than the pinhole 12. As a result, as shown in FIG. 3B , a portion of the second radiation light M2 is blocked by the pinhole 12. Therefore, as shown in FIG. 3C , the light intensity P detected by the second sensor 13 is smaller than when the shift Z of the measurement position 14 is 0. Similarly, when the measurement position 14 is misaligned in the opposite direction, i.e., in the direction in which the optical distance between the measurement position 14 and the second lens 11 increases, the light intensity P detected by the second sensor 13 also decreases. Therefore, as shown in FIG. 3C , when the detected light intensity P of the second sensor 13 is at its maximum, the measurement position 14 and the pinhole 12 are in a conjugate relationship.

[0053] When the shift Z of the measurement position 14 is 0, the measurement position 14 and the pinhole 12 are in a conjugate relationship. At this time, the second radiation light M2 is imaged on the hole of the pinhole 12. The second radiation light M2 reaches the second sensor 13 while spreading from the imaging position of the pinhole 12. Therefore, light with a spot diameter larger than the spot diameter at the imaging position is incident on the second sensor 13. The spot diameter D on the second sensor 13 can be calculated using equation C using the spot diameter d2 at the imaging position of the pinhole 12, the optical distance X between the second sensor 13 and the pinhole 12, and the collection angle θ of the light emitted from the second lens 11.

[0054] D=d2+θX (Formula C) It is preferable that the detector surface size or pixel size of the second sensor 13 is equal to or larger than the spot diameter D.

[0055] The first lens 9 and the second lens 11 may be lenses with a focal length of 25 mm, for example, but lenses with any focal length can be selected depending on the spot diameters d1 and d2.

[0056] The control unit 15 functions as a controller that controls the entire machining state monitoring device 100. The control unit 15 is configured by a processor that realizes predetermined functions by executing programs stored in a built-in recording device, for example. The control unit 15 is not limited to a device that performs predetermined functions through cooperation between hardware and software, but may also be a hardware circuit designed to realize the predetermined functions. In other words, the control unit 15 can be configured by various processors such as a microcomputer, a CPU, an MPU, a GPU, a DSP, an FPGA, an ASIC, etc.

[0057] The control unit 15 adjusts the focusing position of the first radiation M1 by moving the first lens 9 based on the second temperature information acquired by the second sensor 13 .

[0058] Variations occur in the first temperature information due to the thermal lens effect of the processing optical element 3. For this reason, the control unit 15 adjusts the focusing position of the first radiation M1 by moving the position of the first lens 9 based on the second temperature information, thereby suppressing the variations in the first temperature information.

[0059] The thermal lens effect occurs when the processing optical element 3 is heated due to the high output of the laser light L1.

[0060] Fig. 4A is a schematic diagram showing the state of the laser beam L1 and the first emitted light M1 when the thermal lens effect is not occurring, Fig. 4B is a schematic diagram showing the state of the laser beam L1 and the first emitted light M1 when the thermal lens effect is occurring, and Fig. 4C is a schematic diagram for explaining adjustment of the position of the first lens 9 when the thermal lens effect is occurring.

[0061] As shown in Figures 4A and 4B, the laser beam L1 has a Gaussian intensity distribution G with a strong central intensity. Therefore, irradiation of the laser beam L1 increases the temperature near the center of the optical processing element 3. For example, if the optical processing element 3 is a single lens as shown in Figures 4A to 4C, the temperature of the optical processing element 3 increases significantly at the center of the lens, where the temperature change is greater than around the lens. Specifically, the optical processing element 3 is heated by irradiation of the laser beam L1, and the central portion of the optical processing element 3 expands from thickness C1 to thickness C2, as shown in Figures 4A and 4B. Meanwhile, the peripheral portion of the lens, where the temperature change is smaller than around the lens, expands from thickness E1 to thickness E2. The expansion width around the lens is smaller than that of the central portion of the optical processing element 3.

[0062] The difference in the expansion width between the periphery and the center of the lens causes deviation from the originally designed surface shape of the optical processing element 3. As a result, the focal length of the optical processing element 3 changes to focal length f30, causing a phenomenon called the thermal lens effect, in which defocusing occurs, shifting the focal position by a distance DF. Due to the thermal lens effect, the focal position of the laser light L1 moves from the processing portion 6 to the focal position 60. Therefore, as shown in FIG. 4B , the spot diameter at the processing portion 6 becomes larger than when the thermal lens effect does not occur.

[0063] If the processing optical element 3 is a single lens, as described above, the expansion width of the central part of the lens increases, and therefore the focal length of the processing optical element 3 decreases due to the thermal lens effect. In other words, the focusing position often moves toward the laser oscillator 1. On the other hand, if the processing optical element 3 is configured not as a single lens but as an aspherical lens or a combination lens, the direction or magnitude of the shift in the focusing position is determined by the material or configuration of the lens. Therefore, the shift in the focusing position may not be from the processing portion 6 toward the laser oscillator 1, but may be from the processing portion 6 toward the opposite side of the laser oscillator 1. Furthermore, the processing optical element 3 is configured as a single lens, an aspherical lens, a combination lens, an fθ lens, or the like. Regardless of which lens the processing optical element 3 is configured as, the thermal lens effect can occur.

[0064] The first radiation M1 from the processing portion 6 passes through the processing optical element 3 and reaches the first sensor 10. As described above, the processing optical element 3 is heated by the laser beam L1. As described above, the thermal lens effect caused by the heating of the processing optical element 3 changes the focal length f3 of the processing optical element 3 shown in FIG. 4A to the focal length f30 shown in FIG. 4B . This causes a shift in the imaging position of the first radiation M1. Due to the shift in the imaging position of the first radiation M1, the spot diameter d1 of the first radiation M1 on the first sensor 10 becomes larger than when the thermal lens effect is not occurring. As a result, the spot diameter d1 becomes larger than the detector surface size or pixel size of the first sensor 10, making it difficult to accurately acquire first temperature information, which is information about the temperature of the processing portion 6.

[0065] Therefore, the spot diameter d1 on the first sensor 10 can be adjusted by moving the position of the first lens 9 in the optical axis direction based on the second temperature information acquired by the second sensor 13, thereby making it possible to acquire the first temperature information with higher accuracy. The adjustment of the position of the first lens 9 can be achieved, for example, by fixing the first lens 9 to a stage mechanism (not shown) such as a linear stage that is movable in the optical axis direction of the first lens 9, and moving the first lens 9 a predetermined distance.

[0066] As shown in Figure 4C, the relationship of formula D holds among the optical distance S1 between the first sensor 10 and the first lens 9, the optical distance S0 between the first lens 9 and the processing optical element 3, the optical distance S2 between the processing optical element 3 and the processing portion 6, the focal length f0 of the first lens 9, the focal length f2 of the second lens 11 when the thermal lens effect occurs, and the composite focal length fc of the focal length f0 and the focal length f2.

[0067] 1 / fc=1 / fc+1 / f2-S0 / (f0×f2) (Equation D) The relationship of Equation E holds between the optical distance S1, the optical distance S2, and the composite focal length fc.

[0068] 1 / S1+1 / S2=1 / fc (Equation E) The relationship between equations F and G is established by equations D, E, and S1=f0.

[0069] 1 / S2=1 / f2-S0 / (f0×f2) (Equation F) S2=f0×f2 / (f-f2) (Equation G) The control unit 15 acquires in advance the relationship between the second temperature information acquired by the second sensor 13 and the spot diameter d1 of the first radiation light M1 on the first sensor 10. Furthermore, the control unit 15 can estimate the focal length f2 of the second lens 11 when the thermal lens effect occurs, based on the relationship between the second temperature information acquired in advance and the spot diameter d1 of the first radiation light M1. Using the estimated focal length f2, the control unit 15 can minimize the spot diameter d1 of the first radiation light M1 incident on the first sensor 10 by moving the first lens 9 in the optical axis direction so that the optical distance S2 between the processing optical element 3 and the processing unit 6 satisfies Equation F and Equation G. In this way, the first temperature information can be acquired more accurately by the first sensor 10.

[0070] For example, let us consider a case where the laser oscillator 1 is configured with a fiber laser and an fθ lens with a focal length of 250 mm is used as the processing optical element 3. With a laser power of 1 kW, after 120 seconds of laser irradiation, the focal position of the laser light L1 shifts by 0.45 mm, and the spot diameter at the processing area 6 is approximately twice that when the focal position shift is 0 mm. With a laser power of 3 kW, after 120 seconds of laser irradiation, the focal position of the laser light L1 shifts by 1.8 mm, and the spot diameter at the processing area 6 is approximately 8.1 times that when the focal position shift is 0 mm. With a laser power of 6 kW, after 120 seconds of laser irradiation, the focal position of the laser light L1 shifts by 3.2 mm, and the spot diameter at the processing area 6 is approximately 14.4 times that when the focal position shift is 0 mm. Therefore, it can be seen that the thermal lens effect causes the focal position of the laser light L1 to shift, and the spot diameter at the processing area 6 increases.

[0071] As described above, the ratio m1 of the spot diameter d1 of the first radiation light M1 on the first sensor 10 to the spot diameter of the laser light L1 on the processing unit 6 is, for example, 0.1. In this case, the allowable range of the spot diameter of the laser light L1 on the processing unit 6 is up to 10 times the detector surface size or pixel size of the first sensor 10. When the spot diameter of the laser light L1 on the processing unit 6 is within 10 times the detector surface size or pixel size of the first sensor 10, the spot diameter d1 of the first radiation light M1 on the first sensor 10 falls within the detector surface or pixel. Therefore, when the spot diameter of the laser light L1 on the processing unit 6 is within 10 times the detector surface size or pixel size of the first sensor 10, the first temperature information can be acquired with high accuracy by the first sensor 10. For example, when the detector surface size or pixel size of the first sensor 10 is 0.12 mm, the allowable value of the spot diameter of the laser light L1 on the processing unit 6 is 1.2 mm. Therefore, when the spot diameter of the laser light L1 at the processing unit 6 exceeds 10 times the detector surface size or pixel size of the first sensor 10 based on the second temperature information, the control unit 15 may control the position of the first lens 9 to adjust the spot diameter d1 of the first radiation light M1. By moving the first lens 9, the spot diameter d1 of the first radiation light M1 is adjusted to be within 10 times the detector surface size or pixel size of the first sensor 10, so that the first temperature information can be acquired more accurately by the first sensor 10.

[0072] After adjusting the position of the first lens 9 to minimize the spot diameter d1 of the first radiation light M1, the control unit 15 can determine the processing state of the laser processing using the laser light L1 based on the first temperature information.

[0073] As a result of determining the processing state of the laser processing, the control unit 15 can calculate parameters for changing the processing conditions of the laser processing, such as the magnitude of the laser output of the laser oscillator 1 or ON / OFF of the laser oscillator. Furthermore, the control unit 15 can control the laser oscillator 1 based on the processing state change parameters. Furthermore, the control unit 15 can transmit the change parameters to an output device including at least one of a monitor and a speaker.

[0074] [Control of the machining state monitoring device] Next, the control of the machining state monitoring device 100 will be described with reference to Fig. 5. Fig. 5 is a flowchart for explaining the control of the machining state monitoring device 100.

[0075] In step S1, the control unit 15 of the machining state monitoring device 100 acquires first temperature information based on the first radiation M1 detected by the first sensor 10. The first temperature information is acquired as information on the temperature in the machining unit 6, in the form of the intensity of a voltage generated by photoelectric conversion of the first radiation M1 detected by the first sensor 10.

[0076] Next, in step S2, the control unit 15 acquires second temperature information based on the second radiation M2 detected by the second sensor 13. Similar to the first temperature information, the second temperature information is acquired as information on the temperature at the measurement position 14, which is the intensity of a voltage generated by photoelectric conversion of the second radiation M2 detected by the second sensor 13.

[0077] Next, in step S3, the control unit 15 controls the position of the first lens 9. In step S3, the control unit 15 controls the position of the first lens based on the second temperature information. Specifically, as described above, the control unit 15 estimates the focal length f2 of the second lens 11 when the thermal lens effect occurs, based on the relationship between the previously acquired second temperature information and the spot diameter d1 of the first radiation light M1. Using the estimated focal length f2, the control unit 15 moves the first lens 9 in the optical axis direction so that the optical distance S2 between the processing optical element 3 and the processing unit 6 satisfies formulas F and G, thereby minimizing the spot diameter d1 of the first radiation light M1 incident on the first sensor 10. Minimizing the spot diameter d1 of the first radiation light M1 incident on the first sensor 10 allows the first sensor 10 to accurately acquire the first temperature information.

[0078] Next, in step S4, the control unit 15 determines the processing state of the laser processing based on the first temperature information acquired after adjusting the position of the first lens 9. By adjusting the position of the first lens 9, it is possible to acquire more accurate first temperature information. This allows the control unit 15 to more accurately determine the processing state.

[0079] [Effects] According to the above-described embodiment, the following effects can be achieved.

[0080] The processing state monitoring device 100 is a device for monitoring the processing state during laser processing, and includes a first sensor 10 and a second sensor 13. The first sensor 10 detects a first radiation M1 from a processing portion 6 of a workpiece 4, and acquires first temperature information related to the temperature of the processing portion 6 based on the first radiation M1. The processing portion 6 is a part of the workpiece 4, and receives the laser light L1 emitted from the laser oscillator 1 via the processing optical element 3. The second sensor 13 detects a second radiation M2 from the processing optical element 3, and acquires second temperature information related to the temperature of the processing optical element 3 based on the second radiation M2.

[0081] With this configuration, it is possible to provide a processing state monitoring device that improves the accuracy of temperature measurement of the processed portion during laser processing.

[0082] The machining state monitoring device 100 may further include a first branching element that branches the radiation including the first radiation M1 and the second radiation M2 into the first radiation M1 having a wavelength less than a predetermined branching wavelength and the second radiation M2 having a wavelength equal to or greater than the predetermined branching wavelength.

[0083] With this configuration, the first radiation M1 from the processing unit 6 and the second radiation M2 from the processing optical element 3 can be branched, and each radiation can reach the first sensor 10 and the second sensor 13. This further improves the accuracy of temperature measurement of the processing unit 6.

[0084] The predetermined branch wavelength may be 5 μm or more and 10 μm or less.

[0085] With this configuration, it is possible to obtain temperature information of the processing portion 6 and temperature information of the optical processing element 3, which is in a lower temperature range than the processing portion 6, respectively.

[0086] The machining state monitoring device 100 may further include a first lens 9 that focuses the first radiation M1 on the first sensor 10, and a control unit 15 that controls the position of the first lens 9. The control unit 15 may adjust the focusing position of the first radiation M1 by moving the first lens 9 based on the second temperature information. After adjusting the focusing position of the first radiation M1, the control unit 15 may determine the machining state of the laser machining based on the first temperature information.

[0087] With this configuration, the processing state of the laser processing can be determined based on the highly accurate first temperature information, and therefore the processing state can be determined accurately.

[0088] The control unit 15 may calculate a change parameter for the processing conditions of the laser processing based on the first temperature information.

[0089] With this configuration, the processing conditions can be changed appropriately.

[0090] The control unit 15 may control the laser oscillator 1 based on the change parameters of the processing conditions.

[0091] With this configuration, it is possible to automate the change of the laser processing conditions based on the first temperature information.

[0092] The machining state monitoring device 100 may further include an output device including at least one of a monitor and a speaker. The control unit 15 may transmit the change parameters of the machining conditions to the output device.

[0093] With this configuration, the output device can prompt the user to change the processing conditions.

[0094] A pinhole 12 may be disposed between the processing optical element 3 and the second sensor 13. The pinhole 12 may be disposed at a position conjugate with a predetermined measurement position 14 set on the surface or inside of the processing optical element 3.

[0095] With this configuration, the first temperature information can be acquired taking into consideration the shift in the imaging position of the second radiation M2 due to the influence of the expansion of the processing optical element 3, etc.

[0096] The processing optical element 3 may include at least one of a lens and a mirror, and may be made of a material that transmits the first radiation M1.

[0097] With this configuration, the first radiation M1 from the processing unit 6 can be transmitted through the processing optical element 3 and reach the first sensor 10 .

[0098] A method for controlling a laser processing state monitoring device includes acquiring first temperature information, acquiring second temperature information, controlling the position of the first lens 9, and determining the processing state of the laser processing.

[0099] With this configuration, it is possible to provide a method for controlling a processing state monitoring device that improves the accuracy of temperature measurement of a processing portion during laser processing.

[0100] The present disclosure can provide a computer program and a recording medium for controlling the machining state monitoring device 100.

[0101] In the above-described embodiment, the control unit 15 controls the position of the first lens 9 based on the second temperature information, but the present invention is not limited to this. For example, the control unit 15 may control the position of the processing optical element 3 based on the second temperature information.

[0102] In the above-described embodiment, an example has been described in which the control unit 15 is a component of the machining state monitoring device 100, but the present invention is not limited to this. The control unit 15 may be a control unit mounted on a device separate from the machining state monitoring device 100.

[0103] In the above-described embodiment, an example has been described in which the measurement position 14 is a virtually set position inside the processing optical element 3, but the present invention is not limited to this. The measurement position 14 may also be on the surface of the processing optical element 3. The measurement position 14 may be any position as long as it is correlated with the thermal lens effect of the processing optical element 3. Furthermore, if the thermal lens effect is greater in the first mirror 2 than in the processing optical element 3, the measurement position 14 may be set inside or on the surface of the first mirror 2.

[0104] In the above-described embodiment, the spectral mirror 8 is an optical element that reflects light having a wavelength equal to or greater than the predetermined branch wavelength and transmits light having a wavelength less than the predetermined branch wavelength, but is not limited to this. For example, a mirror such as a dichroic mirror that reflects light having a predetermined wavelength and transmits other light may also be used as the spectral mirror 8.

[0105] In the above-described embodiment, a laser oscillator with a maximum output of 3 kW is used, but similar effects can be expected when a high-output laser oscillator of 3 kW or more is used.

[0106] 6 is a schematic diagram illustrating a machining state monitoring device 100A according to Modification 1 of Embodiment 1. As shown in Fig. 6, a band-pass filter 16 may be disposed between the spectral mirror 8 and the first lens 9, and a band-pass filter 17 may be disposed between the spectral mirror 8 and the second lens 11.

[0107] The bandpass filters 16 and 17 can limit the wavelength of light incident on the first sensor 10 and the second sensor 13. For example, the bandpass filter 16 can be one that transmits 90% or more of light having a wavelength of 1.5±0.1 μm and blocks other wavelengths with an optical density of 2 or more and 4 or less. The bandpass filter 17 can be one that transmits 90% or more of light having a wavelength of 6.5±0.1 μm and blocks other wavelengths with an optical density of 2 or more and 4 or less. The use of the bandpass filters 16 and 17 makes it possible to detect specific detection wavelengths, thereby enabling more accurate measurement of the temperature of the processing portion 6.

[0108] (Embodiment 2) Embodiment 2 will be described with reference to Fig. 7. In Embodiment 2, components that are the same as or equivalent to those in Embodiment 1 will be denoted by the same reference numerals. In Embodiment 2, descriptions that overlap with those in Embodiment 1 will be omitted.

[0109] Fig. 7 is a schematic diagram showing a machining state monitoring device 200 according to embodiment 2. As shown in Fig. 7, the machining state monitoring device 100 differs from embodiment 1 in that it includes a third sensor 25 and a fourth sensor 27.

[0110] The third sensor 25 is a sensor that detects visible light M3 from the processing unit 6. The fourth sensor 27 is a sensor that detects reflected light M4 of the laser light L1 from the processing unit 6. The third sensor 25 and the fourth sensor 27 can be configured with photodetectors, similar to the first sensor 10 and the second sensor 13. The third sensor 25 is a sensor that is sensitive to light with a wavelength of at least 0.35 μm or more and 0.7 μm or less. The fourth sensor 27 is a sensor that is sensitive to light with a wavelength of at least 1.07 μm. The third sensor 25 and the fourth sensor 27 may be sensors with a single detector surface or camera-type sensors composed of multiple pixels.

[0111] In this embodiment, the machining state monitoring device 200 has a third lens 24 that focuses visible light M3 on the third sensor 25 and a fourth lens that focuses reflected light M4 on the fourth sensor 27. Furthermore, in this embodiment, the machining state monitoring device 200 has a second branching element that directs visible light M3 toward the third sensor 25 and reflects or transmits reflected light M4 toward the fourth sensor 27. In the example of Fig. 7, the second branching element includes a second mirror 22 and a third mirror 23.

[0112] In this embodiment, laser light L1 emitted from laser oscillator 1 is reflected by first mirror 21 and irradiated onto workpiece 4 via processing optical element 3. Visible light M3 from processing unit 6 reaches third sensor 25 via first mirrors 21, 22, 23, and third lens 24. Reflected light M4 of laser light L1 reflected by processing unit 6 reaches fourth sensor 27 via first mirrors 21, 22, 23, and fourth lens 26. Light including visible light M3 and reflected light M4 from processing unit 6 is reflected by first mirror 21, and most of the light with a wavelength of 1.07 μm is reflected by second mirror 22. Reflected light M4 with a wavelength of 1.07 μm and visible light M3 with a wavelength of 0.35 μm or more and 0.7 μm or less are attenuated by second mirror 22 and reach third mirror 23. Visible light M3 passes through third mirror 23 and is imaged on third sensor 25. The reflected light M 4 is reflected by the third mirror 23 and reaches the fourth sensor 27 .

[0113] The visible light M3 detected by the third sensor 25 includes plasma light generated during processing, and can detect plumes or fumes containing metal particles melted or evaporated by the combustion of foreign matter on the workpiece 4 or by laser irradiation. The reflected light M4 detected by the fourth sensor 27 includes light reflected from the surface of the workpiece 4 during processing, and can detect changes in the surface shape of the molten part on the surface of the workpiece 4 or in the solid and liquid phases.

[0114] The first mirror 21 is disposed at an angle with respect to the optical axis of the laser light L1. The first mirror 21 is disposed at an angle of, for example, 45 degrees with respect to the optical axis of the laser light L1. The first mirror 21 may be a mirror having a coating that reflects the laser light L1 and transmits the light emitted from the processing portion 6. Specifically, the first mirror 21 reflects, for example, 90% or more of the light having a wavelength of 1.07 μm of the laser light L1 and a visible light wavelength of 0.35 μm to 0.7 μm, and transmits at least 10% or more of the light in the reflected wavelength range of 0.35 μm to 10 μm. The wavelengths reflected or transmitted can be changed by changing the configuration of the optical system.

[0115] The second mirror 22 and the third mirror 23 are mirrors that reflect, for example, 90% or more of the light with a wavelength of 1.07 μm of the laser light L1 and transmit 10% or more of visible light between 0.35 μm and 0.7 μm.

[0116] Visible light M3 from processing unit 6 is light with a wavelength of, for example, 0.35 μm or more and 0.7 μm or less, obtained by removing the light with a wavelength of 1.07 μm of laser light L1 from the light from processing unit 6 by second mirrors 22 and 23. Reflected light M4 of laser light L1 reflected by processing unit 6 is light that has leaked slightly after reflection by second mirror 22 and is reflected by third mirror 23, and is light with a wavelength of 1.07 μm of laser light L1.

[0117] The third lens 24 is disposed so that the third sensor 25 and the processing unit 6 are in a conjugate relationship. Visible light M3 from the processing unit 6 is imaged on the third sensor 25 by the third lens 24 via the first mirror 21, the second mirror 22, and the third mirror 23.

[0118] Similarly, the fourth lens 26 is disposed so that the fourth sensor 27 and the processing unit 6 are in a conjugate relationship. The reflected light M4 of the laser light L1 reflected by the processing unit 6 is imaged on the fourth sensor 27 by the fourth lens 26 via the first mirror 21, the second mirror 22, and the third mirror 23.

[0119] The spot diameter of the visible light M3 on the third sensor 25 and the spot diameter of the reflected light M4 on the fourth sensor 27 are preferably smaller than the detector surface size or pixel size of the third sensor 25 and the fourth sensor 27 .

[0120] Because the third sensor 25 and the fourth sensor 27 are each conjugate with the processing unit 6, the spot diameter of the visible light M3 and the spot diameter of the reflected light M4 are determined by the size of the processing area in the processing unit 6. The ratios of the spot diameter of the visible light M3 and the spot diameter of the reflected light M4 to the size of the processing area are defined as ratios m2 and m3, respectively. The ratios m2 and m3 can be expressed by the following formulas H and I using the focal length f4 of the third lens 24, the focal length f5 of the fourth lens 26, and the focal length f3 of the processing optical element 3.

[0121] m2 = f4 / f3 (Equation H) m3 = f5 / f3 (Equation I) For example, if the focal length f3 of the processing optical element 3 is 250 mm, the focal length f4 of the third lens 24 is 25 mm, and the focal length f5 of the fourth lens 26 is 25 mm, the ratio m2 is m2 = 25 / 250 = 0.1, and the ratio m3 is m3 = 25 / 250 = 0.1. In this case, if the size of the processing area in the processing unit 6 is 1 mm, the spot diameters of the visible light M3 and the reflected light M4 are each 0.1 mm. Therefore, under the above conditions, the detector surface size or pixel size of the third sensor 25 and the fourth sensor 27 is preferably larger than 0.1 mm. The detector surface size or pixel size of the third sensor 25 and the fourth sensor 27 should be selected appropriately depending on the focal lengths of the processing optical element 3, the third lens 24, and the fourth lens 26.

[0122] By detecting the visible light M3 or the reflected light M4 in addition to the first temperature information relating to the temperature of the processing portion 6, it becomes possible to estimate the processing state with higher accuracy.

[0123] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0124] (Technology 1) A processing state monitoring device for monitoring a processing state by laser processing, comprising: a first sensor that detects a first radiation light from a processing portion of a processing object that receives laser light emitted from a laser oscillator via a processing optical element and acquires first temperature information related to the temperature of the processing portion based on the first radiation light; and a second sensor that detects a second radiation light from the processing optical element and acquires second temperature information related to the temperature of the processing optical element based on the second radiation light.

[0125] With this configuration, it is possible to provide a processing state monitoring device that improves the accuracy of temperature measurement of the processed portion during laser processing.

[0126] (Technology 2) The machining state monitoring device according to Technology 1 further includes a first branching element that branches the radiation light including the first radiation light and the second radiation light into the first radiation light having a wavelength less than a predetermined branching wavelength and the second radiation light having a wavelength equal to or greater than the predetermined branching wavelength.

[0127] With this configuration, the radiation from the processed portion, including the first radiation and the second radiation, can be split and the radiation in different wavelength ranges can be detected by the first sensor and the second sensor, respectively.

[0128] (Technology 3) The processing state monitoring device according to Technology 2, wherein the predetermined branch wavelength is 5 μm or more and 10 μm or less.

[0129] With this configuration, first temperature information of the processing area generated by high-power laser light and second temperature information of the processing optical element, which has a temperature lower than that of the first temperature information, can be detected in different wavelength ranges.

[0130] (Technology 4) The processing state monitoring device according to any one of Technologies 1 to 3, further comprising at least one of a third sensor that detects visible light from the processing portion or a fourth sensor that detects reflected light of laser light from the processing portion.

[0131] With this configuration, the machining state monitoring device can detect visible light or laser light reflected from the machining portion.

[0132] (Technology 5) The machining state monitoring device according to Technology 1 further includes a third sensor that detects visible light from the machining portion, a fourth sensor that detects reflected light of the laser light from the machining portion, and a second branching element that transmits visible light from the machining point toward the third sensor and reflects reflected light of the laser light from the machining point toward the fourth sensor.

[0133] With this configuration, visible light and reflected light can be efficiently split.

[0134] (Technology 6) The processing state monitoring device according to any one of Technologies 1 to 5, further comprising: a first lens that focuses the first radiation light on the first sensor; and a control unit, wherein the control unit moves the first lens based on the second temperature information to adjust the focusing position of the first radiation light, and after adjusting the focusing position of the first radiation light, determines the processing state of the laser processing based on the first temperature information.

[0135] With this configuration, the influence of the temperature of the processing optical element 3 can be eliminated, and the first temperature information can be acquired with higher accuracy.

[0136] (Technology 7) The processing state monitoring device according to Technology 6, wherein the control unit calculates a change parameter for the processing conditions of the laser processing based on the first temperature information.

[0137] With this configuration, it is possible to change the processing conditions for laser processing based on the first temperature information acquired with high accuracy.

[0138] (Technology 8) The processing state monitoring device according to Technology 7, wherein the control unit controls the laser oscillator based on a change parameter of the processing conditions.

[0139] Such a configuration enables automatic control of the oscillator based on the first temperature information.

[0140] (Technology 9) The machining state monitoring device according to Technology 7, further comprising an output device including at least one of a monitor and a speaker, wherein the control unit transmits the change parameters of the machining conditions to the output device.

[0141] With this configuration, it is possible to prompt the user to change the processing conditions.

[0142] (Technology 10) A processing state monitoring device according to any one of Technologies 1 to 9, wherein a pinhole is arranged between the processing optical element and the second sensor, and the pinhole is arranged at a position conjugate with a predetermined measurement position set on the surface or inside of the processing optical element.

[0143] With this configuration, the second temperature information can be acquired with higher accuracy, and the first temperature information can be acquired taking into account the temperature change of the optical element for processing.

[0144] (Technology 11) The processing state monitoring device according to any one of Technologies 1 to 10, wherein the processing optical element includes at least one of a lens or a mirror and is made of a material that transmits the first synchrotron radiation.

[0145] With this configuration, the first sensor can be disposed so that the first sensor and the processing portion have a conjugate relationship.

[0146] (Technology 12) A method for controlling a laser processing state monitoring device, the method including: acquiring first temperature information from a first sensor that detects first radiation light from a processing portion of a workpiece that receives laser light emitted from a laser oscillator via a processing optical element and acquires first temperature information related to the temperature of the processing portion based on the first radiation light; acquiring second temperature information from a second sensor that detects second radiation light from the processing optical element and acquires second temperature information related to the temperature of the processing optical element; controlling the position of a first lens that focuses the first radiation light on the first sensor based on the second temperature information; and determining the processing state of the laser processing based on the first temperature information after controlling the position of the first lens.

[0147] With this configuration, it is possible to provide a processing state monitoring method that improves the accuracy of temperature measurement of the processed portion during laser processing.

[0148] (Technology 13) A program for causing a computer to execute the method described in Technology 12.

[0149] With this configuration, it is possible to provide a program that improves the accuracy of temperature measurement of the processing area in laser processing.

[0150] (Technology 14) A computer-readable recording medium having a program recorded thereon for causing a computer to execute the method described in Technology 12.

[0151] With this configuration, it is possible to provide a recording medium that improves the accuracy of temperature measurement of the processed portion during laser processing.

[0152] The present disclosure is useful for monitoring the processing state in laser processing.

[0153] REFERENCE SIGNS LIST 1 laser oscillator 2, 21 first mirror 3 processing optical element 4 processing object 5 processing stage 6 processing section 7 filter 8 spectral mirror 9 first lens 10 first sensor 11 second lens 12 pinhole 13 second sensor 14 measurement position 15 control section 22 second mirror 23 third mirror 24 third lens 25 third sensor 26 fourth lens 27 fourth sensor 60 light collection position 100, 100A, 200 processing state monitoring device

Claims

1. A processing state monitoring device for monitoring the processing state by laser processing, comprising: a first sensor that detects a first radiant light from a processing portion of a workpiece that receives laser light emitted from a laser oscillator via a processing optical element, and obtains first temperature information related to the temperature of the processing portion based on the first radiant light; and a second sensor that detects a second radiant light from the processing optical element, and obtains second temperature information related to the temperature of the processing optical element based on the second radiant light.

2. The processing state monitoring device according to claim 1, further comprising: a first branching element that branches the radiation light including the first radiation light and the second radiation light into the first radiation light having a wavelength less than a predetermined branching wavelength and the second radiation light having a wavelength equal to or greater than the predetermined branching wavelength.

3. The machining state monitoring device according to claim 2, wherein the predetermined branch wavelength is 5 μm or more and 10 μm or less.

4. The processing state monitoring device according to claim 1, further comprising at least one of a third sensor that detects visible light from the processing portion and a fourth sensor that detects reflected light of the laser light from the processing portion.

5. The machining state monitoring device according to claim 1, further comprising: a third sensor that detects visible light from the machining portion; a fourth sensor that detects reflected light of the laser light from the machining portion; and a second branching element that transmits visible light from the machining portion toward the third sensor and reflects reflected light of the laser light from the machining portion toward the fourth sensor.

6. The processing state monitoring device according to claim 1, further comprising: a first lens that focuses the first radiation light on the first sensor; and a control unit, wherein the control unit moves the first lens based on the second temperature information to adjust the focusing position of the first radiation light, and after adjusting the focusing position of the first radiation light, determines the processing state of the laser processing based on the first temperature information.

7. The processing state monitoring device according to claim 6, wherein the control unit calculates a parameter for changing the processing conditions for the laser processing based on the first temperature information.

8. The processing state monitoring device according to claim 7, wherein the control unit controls the laser oscillator based on the change parameters of the processing conditions.

9. The machining state monitoring device according to claim 7, further comprising an output device including at least one of a monitor or a speaker, wherein the control unit transmits the change parameters for the machining conditions to the output device.

10. The processing state monitoring device according to claim 1, wherein a pinhole is placed between the processing optical element and the second sensor, and the pinhole is placed at a position conjugate with a predetermined measurement position set on the surface or inside of the processing optical element.

11. The processing state monitoring device according to claim 1, wherein the processing optical element includes at least one of a lens or a mirror, and is made of a material that transmits the first synchrotron radiation.

12. A method for controlling a laser processing state monitoring device, comprising: acquiring first temperature information from a first sensor that detects first radiant light from a processing portion of a workpiece that receives laser light emitted from a laser oscillator via a processing optical element and acquires first temperature information related to the temperature of the processing portion based on the first radiant light; acquiring second temperature information from a second sensor that detects second radiant light from the processing optical element and acquires second temperature information related to the temperature of the processing optical element; controlling the position of a first lens that focuses the first radiant light on the first sensor based on the second temperature information; and determining the processing state of laser processing based on the first temperature information after controlling the position of the first lens.

13. A program for causing a computer to execute the method according to claim 12.

14. A computer-readable recording medium having recorded thereon a program for causing a computer to execute the method according to claim 12.

Images