Laser Processing Equipment

Abstract

To provide a laser machining device suppressing foreign matters from adhering to optical elements.SOLUTION: A laser machining device is provided with a laser beam source emitting laser beam LW for machining a machining target. Further, the laser machining device includes: a laser head having a scan part scanning the laser beam LW emitted from the laser beam source and irradiating the machining target with the laser beam LW; and a control part controlling the laser beam source and the scan part. The laser beam source has an optical window 23 as an optical element transmitting the laser beam LW. The optical window 23 has a thin film body 28 partly absorbing the laser beam LW.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Conventionally, a laser processing device performs marking processing such as characters on a surface of a processing object by irradiating the processing object with a laser light. Such a laser processing device includes a laser light source that emits a laser light, and a laser irradiation unit that irradiates the processing object with the laser light emitted from the laser light source. The laser irradiation unit has, for example, a scanning unit that changes the direction of the laser light emitted from the laser light source based on the desired characters to be marked, and scans the processing object. Each of the laser light source and the laser irradiation unit has at least one optical element. Examples of the optical element include an optical window, a lens, a filter, and a galvanometer mirror.

[0003] However, when impurities floating in the air, such as dust particles, adhere to optical elements, the output of the laser light irradiated onto the workpiece may decrease. As a result, the desired processing state may not be obtained. For this reason, it is necessary to suppress the adhesion of impurities to optical elements.

[0004] For example, the laser processing device described in Patent Document 1 contains a wavelength conversion element, which is likely to have an effect on reducing the output of the laser light if impurities adhere to it, in an airtight manner inside the housing. This prevents impurities in the air from entering the space in which the wavelength conversion element is contained and where the ultraviolet light is transmitted in a narrow state. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-106511 A Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, in order to prevent impurities floating in the air outside a space containing a component including an optical element such as a wavelength conversion element from entering the space, it is preferable to use a sealing structure such as a hermetic seal. However, while a sealing structure such as a hermetic seal is effective for small optical components such as a semiconductor light-emitting element (e.g., a laser diode), it is technically difficult to apply it to a large laser processing device. In addition, the airtight sealing method causes a problem of condensation due to moisture. In order to prevent condensation, it is necessary to place a desiccant in the space containing the optical element and replace the desiccant, which is time-consuming. For these reasons, there is room for improvement in the configuration for preventing impurities from adhering to the optical element. [Means for solving the problem]

[0007] The laser processing apparatus of the present disclosure includes a laser light source that emits laser light for processing an object to be processed, a laser irradiation unit that has a scanning unit that scans the laser light emitted from the laser light source and irradiates the object to be processed with the laser light, and a control unit that controls the laser light source and the scanning unit, and each of the laser light source and the laser irradiation unit has at least one optical element that transmits or reflects the laser light, and the at least one optical element has a thin film that is integrally provided in a portion of the optical element that transmits or reflects the laser light and absorbs a portion of the laser light. By absorbing a portion of the laser light, the thin film is heated to a temperature sufficient to exert a thermophoretic force on impurities contained in the gas in the vicinity of the thin film that is greater than the optical dust collection effect. . Effect of the Invention

[0008] According to the laser processing apparatus of the present disclosure, it is possible to suppress impurities from adhering to optical elements. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic configuration diagram showing a laser processing device according to one embodiment. [Diagram 2]FIG. 2 is a side view diagrammatically illustrating one of the optical elements in the embodiment. [Diagram 3] FIG. 3 is a side view diagrammatically showing one of the optical elements in the laser processing apparatus of the modified example. [Figure 4] FIG. 4 is a side view diagrammatically showing one of the optical elements in the laser processing apparatus of the modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An embodiment of the laser processing device will be described below. In addition, the accompanying drawings may show components enlarged for ease of understanding. In the accompanying drawings, the dimensional ratio of the components may differ from the actual ones or from those in other drawings. In addition, the present invention is not limited to these examples, but is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0011] The laser processing apparatus 10 shown in Fig. 1 includes a laser emission unit 11 and a laser head 12. The laser head 12 corresponds to an example of a "laser irradiation section". [Configuration of laser emission unit 11] The laser emission unit 11 has, for example, a control unit 21 and a laser light source 22. The control unit 21 controls the overall operation of the laser processing apparatus 10. The control unit 21 is electrically connected to each of the laser light source 22 and the laser head 12. The control unit 21 controls the driving of the laser light source 22. The control unit 21 also controls the driving of the laser head 12.

[0012] [Configuration of laser light source 22] The laser light source 22 emits laser light LW including a predetermined wavelength. This laser light LW is for processing the workpiece W. The wavelength included in the laser light LW is, for example, a wavelength in the near-infrared region. For example, the laser light LW includes a wavelength of 1064 nm. The laser light source 22 is a laser light source such as a YAG laser, a CO2 laser, or a fiber laser.

[0013] The laser light source 22 has an optical window 23 that emits the laser light LW. The optical window 23 is one of a plurality of optical elements that constitute the optical system in the laser processing apparatus 10. In this specification, the optical elements that constitute the optical system in the laser processing apparatus 10 include not only general optical elements such as lenses, reflecting mirrors, and filters, but also optical windows and protective glass that transmit the laser light LW. That is, the optical elements in this specification mean parts that transmit the laser light LW or reflect the laser light LW. The optical window 23 transmits the laser light LW in the near-infrared region. The laser light source 22 emits the laser light LW that has passed through the optical window 23.

[0014] 1 and 2, the optical window 23 has an incident surface 23a on which the laser light LW is incident, and an exit surface 23b from which the laser light LW is emitted. The incident surface 23a is the surface of the optical window 23 on which the laser light LW is incident. The exit surface 23b is the surface of the optical window 23 from which the laser light LW is emitted. The exit surface 23b is exposed to the inside of the laser head 12. The optical window 23 has an anti-reflection film (AR coating) 25 on the incident surface 23a. In addition, the optical window 23 has an anti-reflection film 26 on the exit surface 23b. That is, the optical window 23 has anti-reflection films 25, 26 on the surfaces of the optical window 23.

[0015] As shown in FIG. 2, the optical window 23 has a base material 27. The base material 27 is, for example, a glass substrate. The glass substrate is made of, for example, fused quartz. The antireflection films 25, 26 are integrally formed on the surface of the base material 27. The antireflection films 25, 26 improve the transmission amount (transmittance) of the laser light through the base material 27 by reducing the reflection amount (reflectance) of the laser light on the base material 27. Each of the antireflection films 25, 26 is a multilayer film made of a plurality of thin films of materials such as oxides, metals, rare earth elements, etc. Each of the antireflection films 25, 26 is made of, for example, thin films of aluminum oxide (Al2O3), tantalum pentoxide (Ta2O5), magnesium fluoride (MgF2), etc. Each of the antireflection films 25, 26 is integrally formed on the surface of the base material 27 by vapor deposition.

[0016] For example, the optical window 23 has a thin film 28 that is integrally provided on a portion of the optical window 23 that transmits the laser light LW and absorbs a portion of the laser light LW. The thin film 28 is, for example, integrally provided on the exit surface 23b of the optical window 23. The optical window 23 has the thin film 28, for example, on at least the entire range of the exit surface 23b through which the laser light LW passes. That is, the thin film 28 is provided at least on the exit surface 23b over the entire range of the beam diameter of the laser light LW when the laser light LW passes through the exit surface 23b. The optical window 23 has the thin film 28, for example, over the entire exit surface 23b.

[0017] The thin film 28 is configured to generate heat up to a desired temperature by absorbing a portion of the laser light LW. Specifically, for example, the wavelength of the laser light absorbed by the thin film 28 and the film thickness of the thin film 28 are set so that the amount of laser light LW absorbed by the thin film 28 is an amount that allows the thin film 28 to generate heat up to a desired temperature. In other words, the laser light absorptance of the thin film 28 is a value that allows the thin film 28 to rise to a desired range of temperature by absorbing a portion of the laser light LW.

[0018] Here, the gas inside the laser head 12 contains impurities. The impurities include minute liquid and solid particles. In general, when a laser beam is irradiated into a gas containing impurities, the impurities in the gas are subjected to a light collection effect that moves toward the laser beam or the optical element irradiated with the laser beam. The light collection effect on the impurities is greater as the intensity of the laser beam increases. In addition, when the impurities are in a gas having a temperature gradient, the impurities are subjected to a thermophoretic force that moves them from the high temperature side to the low temperature side. The thermophoretic force on the impurities is greater as the temperature gradient between the high temperature side and the low temperature side increases.

[0019] The thin film 28 is configured to absorb a part of the laser light LW, thereby increasing the temperature by a sufficient amount to cause a thermophoretic force greater than the light collection effect to act on impurities contained in the gas inside the laser head 12 in the vicinity of the emission surface 23b. That is, the above-mentioned "desired temperature" is a temperature that can form a temperature gradient in the vicinity of the emission surface 23b that can cause a thermophoretic force greater than the light collection effect to act on impurities floating in the vicinity of the emission surface 23b. For example, the thin film 28 is configured to absorb a part of the laser light LW and generate heat, thereby becoming a temperature several degrees higher than the room temperature of the place where the laser processing device 10 is placed, for example, about 5°C higher. Note that, even if the thin film 28 absorbs a part of the laser light LW, it is preferable that the thin film 28 does not generate heat to the extent that it increases the ambient temperature of the laser light source 22, for example, the temperature of the entire inside of the laser head 12. Even if the thin film 28 absorbs a part of the laser light LW, it is configured not to generate heat to the extent that it becomes a temperature equal to or higher than the heat resistance temperature of the optical window 23.

[0020] The thin film 28 is included in, for example, the antireflection film 26. When the thin film 28 is included in the antireflection film 26, the thin film 28 is formed by deposition when the antireflection film 26 is formed by deposition. Therefore, the thin film 28 is laminated on the surface of the base material 27 together with the multiple thin films that constitute the antireflection film 26. The thin film 28 of the optical window 23 that transmits the laser light LW in the near-infrared region is, for example, a zinc oxide (ZnO)-based thin film.

[0021] When the thin film 28 is included in the antireflection film 26, the thin film 28 may be laminated so as to be adjacent to any of the multiple thin films constituting the antireflection film 26. For example, the antireflection film 26 may be configured such that a first layer in contact with the air around the optical window 23 is a thin film different from the thin film 28, a second layer adjacent to the first layer is the thin film 28, and a third layer adjacent to the second layer and adjacent to the surface of the base material 27 is a thin film different from the thin film 28. In this case, the first layer and the third layer may be configured with only one thin film, or may be configured with multiple thin films laminated. Also, for example, the antireflection film 26 may be configured such that a first layer in contact with the air around the optical window 23 is the thin film 28, and a second layer adjacent to the first layer and adjacent to the surface of the base material 27 is a thin film different from the thin film 28. In this case, the second layer is configured with multiple thin films laminated. Also, for example, the antireflection film 26 may have a configuration in which a first layer in contact with the air surrounding the optical window 23 is a thin film different from the thin film 28, and a second layer adjacent to the first layer and adjacent to the surface of the substrate 27 is the thin film 28. In this case, the first layer has a configuration in which a plurality of thin films are laminated.

[0022] Furthermore, the wavelength of the laser light having the highest absorption rate in the thin film 28 is, for example, a wavelength different from the peak wavelength of the spectrum of the laser light LW transmitted through the optical window 23. More preferably, the wavelength of the laser light having the highest absorption rate in the thin film 28 is set to a wavelength of a part as flat as possible away from a peak on the spectrum of the laser light LW transmitted through the optical window 23 having the thin film 28. When there are multiple peaks on the spectrum of the laser light LW, it is preferable to set the wavelength of the laser light having the highest absorption rate in the thin film 28 to a wavelength of a part as flat as possible away from a peak or a maximum point, that is, a wavelength of a part that is not steep away from the peak.

[0023] In this thin film 28, the material, absorption wavelength, layering order in the anti-reflection film 26, etc. are set so that a thermophoretic force greater than the light collection effect can be exerted on impurities near the exit surface 23b.

[0024] [Laser head 12 configuration] 1, the laser head 12 has, for example, a beam expander 31, a focus adjustment unit 32, a scanning unit 33, and a protective glass 34. The laser head 12 has a housing 35. The beam expander 31, the focus adjustment unit 32, and the scanning unit 33 are accommodated inside the housing 35.

[0025] [Beam Expander 31 Configuration] The beam expander 31 is disposed between the laser light source 22 and the scanning unit 33. The beam expander 31 expands the beam diameter of the laser light LW emitted from the laser light source 22. The beam expander 31 has a plurality of optical elements. For example, the beam expander 31 has two lenses, a first lens 41 on which the laser light LW is incident, and a second lens 42 on which the laser light LW transmitted through the first lens 41 is incident. Each of the first lens 41 and the second lens 42 is an optical element constituting an optical system in the laser processing apparatus 10. That is, the beam expander 31 may have two optical elements.

[0026] The first lens 41 on the incident side of the beam expander 31 is, for example, a concave lens. The second lens 42 on the exit side of the beam expander 31 is a convex lens. The first lens 41 and the second lens 42 may both be convex lenses. The beam expander 31 expands the beam diameter of the incident laser light LW at a magnification according to the distance between the first lens 41 and the second lens 42 and outputs the expanded beam. The beam diameter of the laser light LW passing through the second lens 42 is larger than the beam diameter of the laser light LW passing through the first lens 41.

[0027] The beam expander 31 has a housing 43 that holds a first lens 41 and a second lens 42. The beam expander 31 is, for example, of a sealed type. That is, the beam expander 31 is configured to prevent air outside the housing 43 and impurities in the air from entering the inside of the housing 43.

[0028] The first lens 41 has an incident surface 41a on which the laser light LW is incident, and an exit surface 41b from which the laser light LW is emitted. The incident surface 41a and the exit surface 41b are part of the surface of the first lens 41. The incident surface 41a is exposed to the outside of the housing 43, i.e., the inside of the laser head 12. The exit surface 41b is exposed to the inside of the housing 43. The second lens 42 has an incident surface 42a on which the laser light LW transmitted through the first lens 41 is incident, and an exit surface 42b from which the laser light LW is emitted. The incident surface 42a and the exit surface 42b are part of the surface of the second lens 42. The incident surface 42a is exposed to the inside of the housing 43. The exit surface 42b is exposed to the outside of the housing 43.

[0029] The first lens 41 has an anti-reflection coating 45 on the incident surface 41a. The first lens 41 also has an anti-reflection coating 46 on the exit surface 41b. That is, the first lens 41 has anti-reflection coatings 45, 46 on the surface of the first lens 41. The second lens 42 has an anti-reflection coating 47 on the incident surface 42a. The second lens 42 also has an anti-reflection coating 48 on the exit surface 42b. That is, the second lens 42 has anti-reflection coatings 47, 48 on the surface of the second lens 42.

[0030] The first lens 41 has a substrate 51. The substrate 51 is, for example, a glass substrate similar to the substrate 27. The antireflection films 45, 46 are integrally formed on the surface of the substrate 51. Each of the antireflection films 45, 46 is a multilayer film composed of multiple thin films of materials such as oxides, metals, and rare earth elements, similar to the antireflection films 25, 26. Each of the antireflection films 45, 46 may have the same configuration as the antireflection film 25 or the antireflection film 26, or may have a different configuration. Each of the antireflection films 45, 46 is integrally formed on the surface of the substrate 51 by vapor deposition.

[0031] The second lens 42 has a substrate 52. The substrate 52 is, for example, a glass substrate similar to the substrate 51. The antireflection films 47, 48 are integrally formed on the surface of the substrate 52. Each of the antireflection films 47, 48 is a multilayer film composed of multiple thin films of materials such as oxides, metals, and rare earth elements, similar to the antireflection films 45, 46. Each of the antireflection films 47, 48 may have the same configuration as the antireflection film 46, or may have a different configuration. Each of the antireflection films 47, 48 is integrally formed on the surface of the substrate 52 by vapor deposition.

[0032] For example, the first lens 41 has a thin film 53 that is integrally provided on a portion of the first lens 41 that transmits the laser light LW and absorbs a part of the laser light LW. The thin film 53 is, for example, integrally provided on the incident surface 41a of the first lens 41. The first lens 41 has the thin film 53, for example, on at least the entire range of the incident surface 41a where the laser light LW is irradiated. That is, the thin film 53 is provided at least on the incident surface 41a over the entire range of the beam diameter of the laser light LW when the laser light LW is irradiated on the incident surface 41a. The first lens 41 has the thin film 53, for example, over the entire incident surface 41a.

[0033] The thin film 53 has a configuration similar to that of the thin film 28 of the optical window 23. That is, the thin film 53 is configured to absorb a part of the laser light LW, thereby increasing the temperature by a sufficient amount to cause a thermophoretic force larger than the optical dust collection effect to act on impurities contained in the gas inside the laser head 12 near the incident surface 41a.

[0034] The thin film 53 is included in, for example, the antireflection film 45. When the thin film 53 is included in the antireflection film 45, the thin film 53 is formed by deposition when the antireflection film 45 is formed by deposition. Therefore, the thin film 53 is laminated on the surface of the base material 51 together with the multiple thin films that constitute the antireflection film 45. The thin film 53 of the first lens 41 that transmits the laser light LW in the near infrared region is, for example, a zinc oxide (ZnO)-based thin film. When the thin film 53 is included in the antireflection film 45, the thin film 53 may be laminated so as to be adjacent to any of the multiple thin films that constitute the antireflection film 45, similar to the thin film 28 included in the antireflection film 26.

[0035] Furthermore, the wavelength of the laser light having the highest absorption rate in the thin film 53 is, for example, a wavelength different from the peak wavelength of the spectrum of the laser light LW transmitted through the first lens 41 having the thin film 53. More preferably, the wavelength of the laser light having the highest absorption rate in the thin film 53 is set to a wavelength of a part as flat as possible away from a peak on the spectrum of the laser light LW transmitted through the first lens 41 having the thin film 53. When there are multiple peaks on the spectrum of the laser light LW, it is preferable to set the wavelength of the laser light having the highest absorption rate in the thin film 53 to a wavelength of a part as flat as possible away from a peak or a maximum point, that is, a part that is not steep away from the peak.

[0036] In this thin film 53, the material, absorption wavelength, layering order in the anti-reflection film 45, etc. are set so that a thermophoretic force greater than the light collection effect can be exerted on impurities near the incident surface 41a.

[0037] The optical window 23 and the first lens 41 are optical elements arranged on the optical path of the laser light LW before the beam diameter of the laser light LW is expanded by the beam expander 31. The intensity of the laser light LW is higher before the beam diameter of the laser light LW is expanded by the beam expander 31 than after the beam diameter of the laser light LW is expanded by the beam expander 31. Therefore, the optical window 23 and the first lens 41 are arranged in a location where the intensity of the laser light LW is high.

[0038] [Configuration of focus adjustment unit 32] The focus adjustment unit 32 has a lens unit 61 and a drive unit 62. The lens unit 61 includes at least two lenses. The lenses are optical elements that constitute the optical system in the laser processing device 10. Each lens is disposed on the optical path of the laser light LW. At least one lens included in the lens unit 61 is supported movably along the passage path of the laser light LW by a support member (not shown), such as a linear slider. The drive unit 62 moves the movably supported lens along the passage path of the laser light LW under the control of the control unit 21. In this way, the focus adjustment unit 32 adjusts the focal position of the laser light LW.

[0039] [Configuration of scanning unit 33] The scanning unit 33 has galvanometer mirrors 63X, 63Y and a driving unit 64. The galvanometer mirrors 63X, 63Y reflect the laser light LW. Each of the galvanometer mirrors 63X, 63Y is an optical element constituting an optical system in the laser processing apparatus 10. The driving unit 64 rotates the galvanometer mirrors 63X, 63Y. The driving unit 64 is, for example, a motor. The driving unit 64 is controlled by the control unit 21. The galvanometer mirrors 63X, 63Y and the driving unit 64 are configured to scan the laser light LW in two-dimensional directions. For example, the galvanometer mirror 63X and the driving unit 64 scan the laser light LW in the X-axis direction. Also, for example, the galvanometer mirror 63Y and the driving unit 64 scan the laser light LW in the Y-axis direction.

[0040] [Configuration of protective glass 34] The protective glass 34 is attached to a housing 35 of the laser head 12. The housing 35 has an opening 35a through which the laser light LW passes. The protective glass 34 is attached to the housing 35 so as to close the opening 35a. The protective glass 34 prevents objects (e.g., organic matter) and dust generated by processing from entering the inside of the laser head 12 through the opening 35a. The protective glass 34 is an optical element that constitutes the optical system in the laser processing apparatus 10.

[0041] [Operation of the embodiment] The operation of this embodiment will be described. In the laser processing apparatus 10, the laser light source 22 emits a laser light LW from the optical window 23. The laser light LW transmitted through the optical window 23 is incident on the first lens 41 of the beam expander 31. The beam diameter of the laser light LW is expanded by the first lens 41 and the second lens 42, and the laser light LW is emitted from the second lens 42. The laser light LW emitted from the second lens 42 is irradiated onto the workpiece W via the lens unit 61 of the focus adjustment unit 32, the galvanometer mirrors 63X and 63Y of the scanning unit 33, and the protective glass 34. The workpiece W can be processed by this laser light LW.

[0042] In the laser processing apparatus 10, a thin film 28 that absorbs a portion of the laser light LW is provided on the exit surface 23b of the optical window 23 exposed inside the laser head 12. In addition, a thin film 53 that absorbs a portion of the laser light LW is provided on the entrance surface 23a of the first lens 41 exposed inside the laser head 12.

[0043] When the laser light source 22 emits the laser light LW, the thin film 28 of the optical window 23 generates heat by absorbing a part of the laser light LW. More specifically, the part of the thin film 28 through which the laser light LW passes generates heat. As a result, the temperature of the emission surface 23b of the optical window 23 on which the thin film 28 is provided rises. Then, the heat of the thin film 28 is transferred to the air in the vicinity of the part of the emission surface 23b through which the laser light LW passes. Therefore, the temperature rises locally in the vicinity of the part of the emission surface 23b through which the laser light LW passes. Then, a temperature difference occurs between the part of the thin film 28 to which the heat is transferred and the part of the thin film 28 around the part to which the heat is not transferred. By generating such a temperature difference, a thermophoretic effect can be generated in impurities floating in the part of the thin film 28 through which the heat of the thin film 28 is transferred near the emission surface 23b. Impurities floating in the portion of the thin film 28 near the emission surface 23b to which heat has been transferred are subjected to a thermophoretic force moving from the high temperature side to the low temperature side, that is, a thermophoretic force moving them in a direction away from the emission surface 23b.

[0044] The thin film 28 that has absorbed a portion of the laser light LW generates heat to such an extent that the thermophoretic force acting on the impurities in the vicinity of the exit surface 23b generates a temperature gradient in the vicinity of the exit surface 23b that is greater than the optical dust collection effect acting on the impurities due to the irradiation of the inside of the laser head 12 with the laser light LW. Therefore, the impurities floating in the vicinity of the exit surface 23b are subjected to a thermophoretic force greater than the optical dust collection effect. Therefore, the impurities floating in the vicinity of the exit surface 23b move in a direction away from the exit surface 23b. Therefore, it is possible to suppress the adhesion of the impurities floating inside the laser head 12 to the exit surface 23b.

[0045] When the laser light source 22 emits the laser light LW, the thin film 53 of the first lens 41 also generates heat by absorbing a part of the laser light LW, similar to the thin film 28. Then, like the impurities floating near the exit surface 23b, the impurities floating near the entrance surface 41a of the first lens 41 are subjected to a thermophoretic force greater than the light collection effect. Therefore, the impurities floating near the entrance surface 41a move in a direction away from the entrance surface 41a. Therefore, it is possible to prevent the impurities floating inside the laser head 12 from adhering to the entrance surface 41a.

[0046] [Effects of the embodiment] The effects of this embodiment will be described. (1) The laser processing apparatus 10 includes a laser light source 22 that emits a laser light LW for processing a workpiece W. The laser processing apparatus 10 also includes a laser head 12 that has a scanning unit 33 that scans the laser light LW emitted from the laser light source 22 and irradiates the workpiece W with the laser light LW, and a control unit 21 that controls the laser light source 22 and the scanning unit 33. The laser light source 22 has an optical window 23 that is an optical element that transmits the laser light LW. The laser head 12 has a first lens 41 that is an optical element that transmits the laser light LW. The optical window 23 has a thin film 28 that is integrally provided with a portion of the optical window 23 that transmits the laser light LW and absorbs a portion of the laser light LW. The first lens 41 has a thin film 53 that is integrally provided with a portion of the first lens 41 that transmits the laser light LW and absorbs a portion of the laser light LW.

[0047] According to this configuration, the thin film 28, 53 generates heat by absorbing a part of the laser light LW. The heat of the thin film 28, 53 can cause a thermophoretic force greater than the light dust collection effect to act on the impurities floating in the gas near the thin film 28, 53. This thermophoretic force causes the impurities to move in a direction away from the thin film 28, 53. That is, the impurities move in a direction away from the optical window 23 and the first lens 41. Therefore, when the laser light source 22 is emitting the laser light LW, it is possible to suppress the impurities from adhering to the optical window 23 and the first lens 41. As a result, it is possible to suppress a decrease in the laser output of the laser light LW emitted from the laser head 12 toward the workpiece W.

[0048] Furthermore, the laser processing apparatus 10 requires maintenance such as cleaning and replacement of the built-in optical elements. In the present embodiment, the adhesion of impurities to the optical window 23 and the first lens 41 is reduced, so that the maintenance intervals for the optical window 23 and the first lens 41 can be extended.

[0049] (2) Optical window 23, which is one of the optical elements constituting the optical system in laser processing apparatus 10, has anti-reflection film 26 on its surface. Thin film 28 of optical window 23 is included in anti-reflection film 26. First lens 41, which is one of the optical elements constituting the optical system, has anti-reflection film 45 on its surface. Thin film 53 of first lens 41 is included in anti-reflection film 45.

[0050] For example, the antireflection film 26 may be configured such that the first layer in contact with the air around the optical window 23 is a thin film different from the thin film 28, the second layer adjacent to the first layer is the thin film 28, and the third layer adjacent to the second layer and adjacent to the surface of the base material 27 is a thin film different from the thin film 28. Also, for example, the antireflection film 26 may be configured such that the first layer in contact with the air around the optical window 23 is a thin film different from the thin film 28, and the second layer adjacent to the first layer and adjacent to the surface of the base material 27 is a thin film different from the thin film 28. Also, for example, the antireflection film 26 may be configured such that the first layer in contact with the air around the optical window 23 is a thin film different from the thin film 28, and the second layer adjacent to the first layer and adjacent to the surface of the base material 27 is the thin film 28. The same applies to the antireflection film 45 including the thin film 53.

[0051] Needless to say, the thin films 28, 53 are selected so as to exert a thermophoretic force on the impurities in the vicinity of the thin films 28, 53 which is greater than the optical dust collecting effect.

[0052] According to this configuration, the thin film 28 can be easily formed since it can be formed in the same manner as the multiple thin films that make up the antireflection coating 26. Also, the thin film 28 is less likely to peel off from the surface of the optical window 23, for example, compared to when the thin film 28 is formed by applying a material that makes up the thin film 28 to the surface of the optical window 23. The same effect is achieved for the thin film 53 of the first lens 41.

[0053] (3) Laser light LW in the near-infrared region is transmitted through the optical window 23 and the first lens 41. The thin film 28 of the optical window 23 and the thin film 53 of the first lens 41 are zinc oxide-based thin films.

[0054] According to this configuration, each of the thin films 28 and 53 can easily absorb a portion of the laser light LW in the near-infrared region. (4) The laser head 12 has a beam expander 31 disposed between the laser light source 22 and the scanning unit 33 to expand the beam diameter of the laser light LW. The beam expander 31 has a plurality of optical elements. One of the plurality of optical elements is a first lens 41 on which the laser light LW is incident, and another optical element of the plurality of optical elements different from the first lens 41 is a second lens 42 on which the laser light LW transmitted through the first lens 41 is incident. The first lens 41 has a thin film 53.

[0055] According to this configuration, the first lens 41 on the incident side transmits the laser light LW having a smaller beam diameter than the second lens 42 on the exit side. Therefore, the laser light LW has a higher intensity when passing through the first lens 41 than when passing through the second lens 42. Therefore, the light collection effect on impurities floating near the first lens 41 is greater than the light collection effect on impurities floating near the second lens 42. Therefore, when the first lens 41 does not have the thin film 53, impurities are more likely to adhere to the first lens 41 than to the second lens 42. Therefore, by having the thin film 53 on the first lens 41, it is possible to suppress the adhesion of impurities to the first lens 41, which is the first lens 41 that is more likely to have impurities adhere to it. And, by having the thin film 53 on the first lens 41, which is an optical element that is more likely to have impurities adhere to it, it is possible to more effectively suppress a decrease in the laser output of the laser light LW emitted from the laser head 12 toward the workpiece W.

[0056] (5) The laser light source 22 has an optical window 23 that emits the laser light LW. The optical window 23 is one of the optical elements that make up the optical system in the laser processing apparatus 10. The optical window 23 has an entrance surface 23a on which the laser light LW is incident and an exit surface 23b from which the laser light LW exits, and a thin film 28 is provided on the exit surface 23b.

[0057] According to this configuration, the thin film 28 is provided on the exit surface 23b exposed to the inside of the laser head 12. The gas inside the laser head 12 contains impurities. Therefore, there is a concern that impurities may adhere to the exit surface 23b exposed to the inside of the laser head 12 due to the photophoretic effect when the laser light source 22 emits the laser light LW. Therefore, by providing the thin film 28 on the exit surface 23b, it is possible to suppress the adhesion of impurities to the exit surface 23b by the thermophoretic effect.

[0058] Moreover, the laser light LW passing through the optical window 23 is the laser light LW before the beam diameter is expanded by the beam expander 31. Therefore, the intensity of the laser light LW passing through the optical window 23 is higher than the intensity of the laser light LW emitted from the beam expander 31. Therefore, the optical dust collection effect on the impurities floating near the optical window 23 is larger than the optical dust collection effect caused by the laser light LW emitted from the beam expander 31. Therefore, when the optical window 23 does not have the thin film 28, impurities are more likely to adhere to the optical window 23 than an optical element that transmits or reflects the laser light LW whose beam diameter has been expanded by the beam expander 31. Therefore, by having the thin film 28, the optical window 23 can suppress the adhesion of impurities to the optical window 23, which is a high concern regarding the adhesion of impurities. Furthermore, by having the optical window 23, which is an optical element that is more susceptible to the adhesion of impurities, have the thin film 28, it is possible to more effectively prevent a decrease in the laser output of the laser light LW emitted from the laser head 12 toward the workpiece W.

[0059] (6) The optical window 23 has an entrance surface 23a on which the laser light LW is incident and an exit surface 23b from which the laser light LW is emitted. The optical window 23 has a thin film 28 on at least the entire range of the entrance surface 23a or the exit surface 23b, through which the laser light LW passes. The first lens 41 has an entrance surface 41a on which the laser light LW is incident and an exit surface 41b from which the laser light LW is emitted. The first lens 41 has a thin film 53 on at least the entire range of the entrance surface 41a or the exit surface 41b, through which the laser light LW is irradiated.

[0060] When the optical window 23 does not have the thin film 28, the range where the laser light LW passes through on the exit surface 23b of the optical window 23 is a portion where impurities that have been subjected to the light dust collection effect caused by the laser light LW near the exit surface 23b are likely to adhere. Similarly, when the first lens 41 does not have the thin film 53, the range where the laser light LW is irradiated on the entrance surface 41a is a portion where impurities that have been subjected to the light dust collection effect caused by the laser light LW near the entrance surface 41a are likely to adhere. Also, when impurities adhere to the range where the laser light LW passes through on the exit surface 23b of the optical window 23, the laser output of the laser light LW emitted from the laser head 12 toward the workpiece W is more likely to be affected than when impurities adhere outside the range. Similarly, when impurities adhere to the range where the laser light LW is irradiated on the entrance surface 41a of the first lens 41, the laser output of the laser light LW emitted from the laser head 12 toward the workpiece W is more likely to be affected than when impurities adhere outside the range. Therefore, by having the optical window 23 have the thin film 28 over at least the entire range on the emission surface 23b through which the laser light LW passes, it is possible to more effectively prevent a decrease in the laser output of the laser light LW emitted from the laser head 12 toward the work-piece W. Also, by having the thin film 53 over at least the entire range on the incidence surface 41a through which the laser light LW is irradiated, it is possible to more effectively prevent a decrease in the laser output of the laser light LW emitted from the laser head 12 toward the work-piece W.

[0061] (7) The wavelength of the laser light having the highest absorption rate in the thin film 28 is different from the peak wavelength of the spectrum of the laser light LW transmitted through the optical window 23 having the thin film 28. More preferably, the wavelength of the laser light having the highest absorption rate in the thin film 28 is set to a wavelength of a part as flat as possible away from a peak on the spectrum of the laser light LW transmitted through the optical window 23 having the thin film 28. When there are multiple peaks on the spectrum of the laser light LW, it is preferable to set the wavelength of the laser light having the highest absorption rate in the thin film 28 to a wavelength of a part as flat as possible away from a peak or maximum point, that is, a part that is not steep away from the peak.

[0062] The wavelength of the laser light having the highest absorption rate in the thin film 53 is a wavelength different from the peak wavelength of the spectrum of the laser light LW transmitted through the first lens 41 having the thin film 53. More preferably, the wavelength of the laser light having the highest absorption rate in the thin film 53 is set to a wavelength of a part as flat as possible away from a peak on the spectrum of the laser light LW transmitted through the first lens 41 having the thin film 53. When there are multiple peaks on the spectrum of the laser light LW, it is preferable to set the wavelength of the laser light having the highest absorption rate in the thin film 53 to a wavelength of a part as flat as possible away from a peak or a maximum point, that is, a part that is not steep away from the peak.

[0063] Needless to say, the thin films 28, 53 are selected so as to exert a thermophoretic force on the impurities in the vicinity of the thin films 28, 53 which is greater than the optical dust collecting effect.

[0064] According to this configuration, the optical window 23 has the thin film 28, and the first lens 41 has the thin film 53, so that a decrease in the laser output of the laser processing apparatus 10 can be suppressed. (8) In the present embodiment, the optical elements for which it is desired to suppress adhesion of impurities, such as the optical window 23 and the first lens 41, do not need to be housed in an airtight manner. Therefore, it is not necessary to place a desiccant to prevent condensation in the space in which the optical window 23 and the first lens 41 are disposed, or to replace the desiccant. Therefore, it is possible to suppress adhesion of impurities to the optical window 23 and the first lens 41 without increasing the maintenance burden of the laser processing apparatus 10.

[0065] (9) The adhesion of impurities to the surfaces of the optical window 23 and the first lens 41, which are desired to be prevented from adhesion of impurities, is prevented by locally increasing the temperature of the surfaces of the optical window 23 and the first lens 41 by the heat generated by the thin film 28, 53. Therefore, it is not necessary to heat the entire part holding the optical window 23 with a heater or the entire part holding the first lens 41 with a heater. Therefore, it is difficult for a wide area inside the laser light source 22 or a wide area inside the laser head 12 to become hot. Therefore, it is possible to prevent impurities from adhering to the optical window 23 and the first lens 41 without considering the operating temperature of the laser light source 22 or the operating temperature of the laser head 12. Furthermore, it is possible to prevent impurities from adhering to the optical window 23 and the first lens 41 while preventing an increase in the number of parts.

[0066] [Example of change] This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

[0067] In the above embodiment, among the optical elements constituting the optical system in the laser processing apparatus 10, the optical window 23 and the first lens 41 have the thin film 28, 53, respectively. However, among the optical elements constituting the optical system in the laser processing apparatus 10, at least one optical element may have a thin film that is integrally provided in a portion of the optical element that transmits or reflects the laser light LW and absorbs a part of the laser light LW. For example, when the optical window 23 has the thin film 28 and diffused light is emitted from the optical window 23, the first lens 41 may not have the thin film 53. Also, for example, optical elements other than the optical window 23 and the first lens 41 may have a thin film. For example, the second lens 42 may have the thin film 53. Also, for example, each of the galvanometer mirrors 63X and 63Y that reflect the laser light LW may have a thin film. Note that in each of the galvanometer mirrors 63X and 63Y, the incident surface into which the laser light LW is incident and the exit surface from which the laser light LW is emitted are the same surface. Incidentally, in the case of optical elements on the optical path in which the beam diameter of the laser light LW is similar, for example, in the case where the light is parallel from the optical window 23 to the first lens 41 and becomes diffused light from the first lens 41, it is preferable to have a thin film on the optical window 23 and at least on the side of the incident surface 41a of the first lens 41.

[0068] Also, for example, in the laser processing apparatus 10, all optical elements arranged on the optical path of the laser light LW to transmit or reflect the laser light LW may have a thin film that absorbs a part of the laser light LW. In this way, it is possible to suppress the adhesion of impurities to all optical elements.

[0069] The optical window 23 may have the thin film 28 only in an area of ​​at least one of the entrance surface 23a and the exit surface 23b through which the laser light LW passes. Alternatively, the optical window 23 may have the thin film 28 in a part of an area of ​​at least one of the entrance surface 23a and the exit surface 23b through which the laser light LW passes.

[0070] Similarly, the first lens 41 may have the thin film 53 only in an area on at least one of the entrance surface 41a and the exit surface 41b that is irradiated with the laser light LW. The first lens 41 may also have the thin film 53 in a part of an area on at least one of the entrance surface 41a and the exit surface 41b that is irradiated with the laser light LW.

[0071] The optical window 23 may have a thin film 28 provided on the entrance surface 23a. The first lens 41 may have a thin film 53 provided on each of the entrance surface 41a and the exit surface 41b. This can prevent impurities from adhering to both the entrance surface 41a and the exit surface 41b. For example, if the beam expander 31 is not a sealed type, there is a concern that impurities may also adhere to the exit surface 41b. In this case, if the thin film 53 is provided on the exit surface 41b, it can prevent the impurities from adhering to the exit surface 41b.

[0072] In addition to the first lens 41 and the second lens 42, the beam expander 31 may further include another optical element. The thin film of the optical element that transmits the laser light LW in the near infrared region does not necessarily have to be a zinc oxide thin film. As long as it can absorb part of the laser light LW, the thin film may be made of a material other than a zinc oxide material.

[0073] The laser light source 22 may emit laser light LW including a wavelength in the ultraviolet region. In this case, the laser light source 22 has, for example, a laser oscillator that generates a fundamental wave and two wavelength conversion elements. One wavelength conversion element generates a second harmonic having a higher frequency than the fundamental wave (SHG: Second Harmonic Generation). The wavelength of the second harmonic is, for example, 532 nm. The other wavelength conversion element generates a third harmonic having a higher frequency than the second harmonic (THG: Third Harmonic Generation). The wavelength of the third harmonic is, for example, 355 nm, in the ultraviolet region.

[0074] In this case, at least one of the optical elements constituting the optical system in the laser processing apparatus 10 transmits or reflects the laser light LW in the ultraviolet region. For example, the optical window 23 and the first lens 41 transmit the laser light LW in the ultraviolet region. Also, the galvanometer mirrors 63X and 63Y reflect the laser light LW in the ultraviolet region. At least one of the optical elements that transmits or reflects the laser light LW in the ultraviolet region may have a thin film that is a titanium oxide (TiO2)-based thin film that absorbs a part of the laser light LW in the ultraviolet region. For example, the thin films 28 and 53 of the optical window 23 and the first lens 41 are titanium oxide-based thin films. In this way, each of the thin films 28 and 53 can easily absorb a part of the laser light LW in the ultraviolet region. Also, it is possible to suppress impurities from adhering to the optical window 23 and the first lens 41.

[0075] In this case, when the optical element of the laser oscillator and the wavelength conversion element for generating the second harmonic have a thin film, the thin film is preferably a zinc oxide (ZnO) based thin film.

[0076] The laser processing apparatus 10 may include an optical element having an enhanced reflection coating (HR coating). The optical element may have a thin film on its surface that absorbs part of the laser light LW. In this case, the thin film may be included in the enhanced reflection coating. In this way, the thin film can be formed in the same manner as the multiple thin films that make up the enhanced reflection coating, so that the thin film can be easily formed. In addition, the thin film is less likely to peel off from the surface of the optical element compared to, for example, a case in which a thin film is formed by applying a material that makes up the thin film to the surface of the optical element.

[0077] As shown in FIG. 3, the thin film 28 may not be included in the anti-reflection film 26. In the example shown in FIG. 3, the optical window 23 has the anti-reflection film 25 not including the thin film 28 on each of the incident surface 23a and the exit surface 23b. The thin film 28 is integrally provided on the surface of the anti-reflection film 25. For example, the thin film 28 is integrally provided on the optical window 23 by coating the surface of the anti-reflection film 25 after the anti-reflection film 25 is formed on the surface of the base material 27. The surface of the anti-reflection film 25 is the surface of the anti-reflection film 25 opposite to the base material 27. In the example shown in FIG. 3, the thin film 28 is provided on each of the incident surface 23a and the exit surface 23b, but the thin film 28 may be provided on only one of the incident surface 23a and the exit surface 23b. The same may be done for the thin film 53 of the first lens 41.

[0078] As shown in FIG. 4, the optical window 23 may have a thin film 71 instead of the thin film 28. The thin film 71 is integrally provided on the surface of the anti-reflection film 25. When the wavelength of the laser light LW includes a wavelength in the near-infrared region, the thin film 71 is, for example, a titanium oxide-based thin film. The thin film 71 has a concave-convex structure 72 having a large number of fine concaves and convexes that absorb the laser light LW on the surface of the thin film 71. Each concave and each convex in the concave-convex structure 72 has a size on the order of nanometers. In this way, the concave-convex structure 72 can absorb a part of the laser light LW. Therefore, the same effect as that of the above embodiment (1) can be achieved. In the example shown in FIG. 4, the thin film 71 is provided on each of the incident surface 23a and the exit surface 23b, but the thin film 71 may be provided on only one of the incident surface 23a and the exit surface 23b.

[0079] Furthermore, the concave-convex structure 72 may be provided on the surface of the antireflection film 25. In this case, the antireflection film 25 having the concave-convex structure 72 corresponds to a thin film that absorbs a part of the laser light LW. (Appendix 1) A laser light source that emits laser light for processing an object to be processed; a laser irradiation unit having a scanning unit that scans the laser light emitted from the laser light source and irradiates the laser light onto the object to be processed; A control unit that controls the laser light source and the scanning unit, Each of the laser light source and the laser irradiation unit has at least one optical element that transmits or reflects the laser light, At least one of the optical elements has a thin film that is integrally provided on a portion of the optical element that transmits or reflects the laser light and absorbs a portion of the laser light. (Appendix 2) At least one of the optical elements has an anti-reflection coating on a surface thereof; The laser processing apparatus according to claim 1, wherein the thin film is included in the anti-reflection film. (Appendix 3) At least one of the optical elements has a high reflection coating on a surface thereof; The laser processing apparatus according to claim 1 or 2, wherein the thin film is included in the reflection-enhancing film. (Appendix 4) 4. The laser processing apparatus according to claim 1, wherein at least one of the optical elements transmits or reflects the laser light in the ultraviolet region, and the thin film of the optical element is a titanium oxide-based thin film. (Appendix 5) 5. The laser processing apparatus according to claim 1, wherein at least one of the optical elements transmits or reflects the laser light in the near-infrared region, and the thin film possessed by the optical element is a zinc oxide-based thin film. (Appendix 6) the laser irradiation unit has a beam expander disposed between the laser light source and the scanning unit to expand a beam diameter of the laser light, the beam expander has a plurality of the optical elements, one of the plurality of optical elements being a first lens onto which the laser light is incident, and one of the plurality of optical elements other than the first lens being a second lens onto which the laser light transmitted through the first lens is incident, The laser processing apparatus according to any one of claims 1 to 5, wherein the first lens has the thin film. (Appendix 7) The laser processing apparatus of claim 6, wherein the first lens has an incident surface on which the laser light is incident and an exit surface from which the laser light is emitted, and the thin film is provided on each of the incident surface of the first lens and the exit surface of the first lens. (Appendix 8) the laser light source has the optical element which is an optical window through which the laser light is emitted, The laser processing apparatus of any one of appendix 1 to appendix 7, wherein the optical window has an incident surface through which the laser light is incident and an exit surface through which the laser light is exited, and the thin film is provided on the exit surface of the optical window. (Appendix 9) The laser processing apparatus of any one of appendix 1 to appendix 8, wherein at least one of the optical elements has an incident surface on which the laser light is incident and an exit surface from which the laser light is exited, and has the thin film on at least one of the incident surface and the exit surface of the optical element, at least over the entire range where the laser light is irradiated or passes through. (Appendix 10) 10. The laser processing apparatus according to claim 1, wherein all of the optical elements arranged on the optical path of the laser light and transmitting or reflecting the laser light have the thin film. (Appendix 11) 11. The laser processing apparatus according to any one of claims 1 to 10, wherein the wavelength of the laser light having the highest absorption rate in the thin film is a wavelength different from a peak wavelength of the spectrum of the laser light transmitted through the optical element having the thin film or reflected by the optical element having the thin film. [Explanation of symbols]

[0080] 10 Laser processing equipment 11 Laser emission unit 12 Laser head (laser irradiation part) 21 Control section 22 Laser light source 23 Optical window 23a Incidence plane 23b Output surface 25 Anti-reflection coating 26 Anti-reflection coating 27 Base material 28 Thin Film 31 Beam Expander 32 Focus adjustment section 33 Scanning unit 34 Protective Glass 35 Case 35a opening 41 First lens 41a Incidence plane 41b Output surface 42 Second lens 42a Incidence plane 42b Output surface 43 Case 45 Anti-reflection coating 46 Anti-reflection coating 47,48 Anti-reflection coating 51 Base material 52 Base material 53 Thin Film 61 Lens section 62 Drive unit 63X,63Y Galvanometer Mirror 64 Drive unit 71 Thin Film 72 Uneven structure LW laser light W Processing object

Claims

1. A laser light source that emits laser light for processing an object to be processed; a laser irradiation unit having a scanning unit that scans the laser light emitted from the laser light source and irradiates the laser light onto the object to be processed; A control unit that controls the laser light source and the scanning unit; Equipped with Each of the laser light source and the laser irradiation unit has at least one optical element that transmits or reflects the laser light, At least one of the optical elements has a thin film that is integrally provided with a portion of the optical element that transmits or reflects the laser light and absorbs a portion of the laser light, and by absorbing a portion of the laser light, the thin film increases in temperature enough to exert a thermophoretic force on impurities contained in a gas near the thin film that is greater than the optical collection effect.

2. At least one of the optical elements has an anti-reflection coating on a surface thereof; The laser processing apparatus according to claim 1 , wherein the thin film is included in the anti-reflection film.

3. At least one of the optical elements has a high reflection coating on a surface thereof; The laser processing apparatus according to claim 2 , wherein the thin film is included in the reflection enhancing film.

4. 3. The laser processing apparatus according to claim 2, wherein at least one of the optical elements transmits or reflects the laser light in the ultraviolet region, and the thin film of the optical element is a titanium oxide-based thin film.

5. 3. The laser processing apparatus according to claim 2, wherein at least one of the optical elements transmits or reflects the laser light in the near infrared region, and the thin film of the optical element is a zinc oxide-based thin film.

6. the laser irradiation unit has a beam expander disposed between the laser light source and the scanning unit to expand a beam diameter of the laser light, the beam expander has a plurality of the optical elements, one of the plurality of the optical elements is a first lens onto which the laser light is incident, and one of the plurality of the optical elements other than the first lens is a second lens onto which the laser light transmitted through the first lens is incident, The laser processing apparatus according to claim 2 , wherein the first lens has the thin film.

7. 7. The laser processing apparatus according to claim 6, wherein the first lens has an incident surface on which the laser light is incident and an exit surface from which the laser light is emitted, and the thin film is provided on each of the incident surface of the first lens and the exit surface of the first lens.

8. the laser light source has the optical element which is an optical window through which the laser light is emitted, 3. The laser processing apparatus according to claim 2, wherein the optical window has an entrance surface on which the laser light is incident and an exit surface from which the laser light is exited, and the thin film is provided on the exit surface of the optical window.

9. 3. The laser processing apparatus of claim 2, wherein at least one of the optical elements has an incident surface on which the laser light is incident and an exit surface from which the laser light is emitted, and the thin film is provided over at least the entire area on at least one of the incident surface and the exit surface of the optical element through which the laser light is irradiated or passes.

10. 3. The laser processing apparatus according to claim 2, wherein all of the optical elements arranged on the optical path of the laser light and transmitting or reflecting the laser light include the thin film.

11. 3. The laser processing apparatus according to claim 2, wherein the wavelength of the laser light having the highest absorption rate in the thin film is a wavelength different from the peak wavelength of the spectrum of the laser light transmitted through the optical element having the thin film or reflected by the optical element having the thin film.

Images