WO2023042543A1

WO2023042543A1 - Laser processing device

Info

Publication number: WO2023042543A1
Application number: PCT/JP2022/028232
Authority: WO
Inventors: 哲司高御堂
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2021-09-16
Filing date: 2022-07-20
Publication date: 2023-03-23
Also published as: JP2023043726A

Abstract

This laser processing device is provided with a laser light source for emitting laser light (LW) for processing a processing subject. In addition, this laser processing device is provided with a laser head, which has a scanning unit for scanning the laser light (LW) emitted from the laser light source, and which irradiates the processing subject with the laser light (LW), and a control unit, which controls the laser light source and the scanning unit. The laser light source has an optical window (23), which is an optical element through which the laser light (LW) passes. The optical window (23) has a thin-film body (28) for absorbing a portion of the laser light (LW).

Description

Laser processing equipment

This disclosure relates to a laser processing apparatus.

Conventionally, a laser processing apparatus performs marking processing such as characters on the surface of a processing target by irradiating the processing target with a laser beam. Some of such laser processing apparatuses have a laser light source that emits laser light, and a laser irradiation section that irradiates a processing object with the laser light emitted from the laser light source. The laser irradiation unit has a scanning unit that scans the object to be processed by changing the direction of the laser light emitted from the laser light source based on, for example, a desired character or the like to be marked. Each of the laser light source and the laser irradiation section has at least one optical element. Examples of optical elements include optical windows, lenses, filters, and galvanomirrors.

By the way, when impurities floating in the air such as dust adhere to the optical element, the output of the laser beam irradiated to the object to be processed may decrease. As a result, the desired processing state may not be obtained. Therefore, it is required to prevent impurities from adhering to the optical element.

For example, the laser processing apparatus described in Patent Document 1 airtightly houses a wavelength conversion element inside a housing, which tends to reduce the output of laser light when impurities adhere to it. This prevents impurities in the air from entering the space where the wavelength conversion element is accommodated and where the ultraviolet light is transmitted in a narrow state.

JP 2019-106511 A

By the way, in order to prevent impurities floating in the air outside the space from entering the space in which components including optical elements such as wavelength conversion elements are accommodated, it is possible to use a sealing structure such as a hermetic seal. preferable. However, while sealing structures such as hermetic seals are effective for small optical components such as semiconductor light emitting devices (for example, laser diodes), they are technically difficult to apply to large laser processing apparatuses. In addition, the hermetic sealing method has a problem of dew condensation due to moisture. In order to prevent dew condensation, it takes time and effort to arrange a dehumidifying agent in the space in which the optical element is accommodated, or to replace the dehumidifying agent. For these reasons, there is room for improvement in terms of the structure that prevents impurities from adhering to the optical element.

A laser processing apparatus of the present disclosure includes a laser light source that emits laser light for processing an object to be processed, and a scanning unit that scans the laser light emitted from the laser light source. A laser irradiation unit that irradiates an object, and a control unit that controls the laser light source and the scanning unit, wherein each of the laser light source and the laser irradiation unit transmits or reflects the laser light. It has one optical element, and at least one of the optical elements has a thin film body that is integrally provided in a portion of the optical element that transmits or reflects the laser beam and that absorbs part of the laser beam.

According to the laser processing apparatus of the present disclosure, adhesion of impurities to the optical element can be suppressed.

FIG. 1 is a schematic configuration diagram showing a laser processing apparatus according to one embodiment. FIG. 2 is a side view schematically showing one of the optical elements in the same embodiment. FIG. 3 is a side view schematically showing one of the optical elements in the laser processing apparatus of the modification. FIG. 4 is a side view schematically showing one of the optical elements in the laser processing apparatus of the modification.

An embodiment of the laser processing apparatus will be described below.
It should be noted that the attached drawings may show constituent elements on an enlarged scale for easy understanding. In the accompanying drawings, the dimensional proportions of components may differ from the dimensional proportions of actual components or from the dimensional proportions of components in separate figures. It should be noted that the present invention is not limited to these examples, but is indicated by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

A laser processing apparatus 10 shown in FIG. 1 includes a laser emitting unit 11 and a laser head 12 . The laser head 12 corresponds to an example of a "laser irradiation section".
[Configuration of Laser Emitting Unit 11]
The laser emission unit 11 has, for example, a control section 21 and a laser light source 22 . The control unit 21 controls the overall operation of the laser processing device 10 . The controller 21 is electrically connected to each of the laser light source 22 and the laser head 12 . The controller 21 controls driving of the laser light source 22 . Also, the control unit 21 controls driving of the laser head 12 .

[Configuration of laser light source 22]
The laser light source 22 emits laser light LW containing a predetermined wavelength. This laser beam LW is for processing the object W to be processed. The wavelengths contained in the laser light LW are, for example, wavelengths in the near-infrared region. For example, laser light LW includes a wavelength of 1064 nm. The laser light source 22 is a laser light source such as a YAG laser, _CO2 laser, fiber laser, or the like.

The laser light source 22 has an optical window 23 for emitting laser light LW. The optical window 23 is one of a plurality of optical elements forming an optical system in the laser processing apparatus 10 . In this specification, the optical elements that make up the optical system in the laser processing apparatus 10 are not only general optical elements such as lenses, reflecting mirrors, and filters, but also optical windows and protective glass that transmit the laser beam LW. shall be included. That is, the optical element in this specification means a component that transmits the laser beam LW or reflects the laser beam LW. The optical window 23 transmits laser light LW in the near-infrared region. The laser light source 22 emits laser light LW that has passed through the optical window 23 .

As shown in FIGS. 1 and 2, the optical window 23 has an incident surface 23a on which the laser beam LW is incident and an output surface 23b from which the laser beam LW is emitted. The incident surface 23a is the surface of the optical window 23 on which the laser beam LW is incident. The exit surface 23b is the surface of the optical window 23 from which the laser beam LW is emitted. The emission surface 23 b is exposed inside the laser head 12 . The optical window 23 has an antireflection film (AR coat) 25 on the incident surface 23a. Further, the optical window 23 has an antireflection film 26 on the exit surface 23b. That is, the optical window 23 has

antireflection films

25 and 26 on the surface of the optical window 23 .

As shown in FIG. 2, optical window 23 has substrate 27 . The base material 27 is, for example, a glass substrate. The glass substrate is made of fused silica, for example. The

antireflection films

25 and 26 are integrally formed on the surface of the base material 27 . The

antireflection films

25 and 26 improve the amount of laser light transmitted through the base material 27 (transmittance) by reducing the amount of laser light reflected by the base material 27 (reflectance). Each of the

antireflection films

25 and 26 is a multilayer film composed of a plurality of thin films of materials such as oxides, metals and rare earth elements. Each of the

antireflection films

25 and 26 is composed of a thin film of, for example, aluminum oxide (Al ₂ O ₃ ), tantalum pentoxide (Ta ₂ O ₅ ), magnesium fluoride (MgF ₂ ), or the like. Each of the

antireflection films

25 and 26 is integrally formed on the surface of the substrate 27 by vapor deposition.

For example, the optical window 23 has a thin film body 28 that is integrally provided in a portion of the optical window 23 through which the laser beam LW is transmitted and absorbs part of the laser beam LW. The thin film body 28 is provided integrally with the exit surface 23b of the optical window 23, for example. The optical window 23 has, for example, a thin film 28 over at least the entire range through which the laser beam LW passes on the exit surface 23b. That is, the thin film 28 is provided at least on the exit surface 23b over the entire beam diameter range of the laser beam LW when the laser beam LW passes through the exit surface 23b. In one example, the thin film 28 does not have to be provided in a region of the emission surface 23b of the optical window 23 other than the range through which the laser beam LW passes. Alternatively, the optical window 23 may have a thin film 28 over the exit surface 23b.

The thin film body 28 is configured to generate heat up to a desired temperature by absorbing part of the laser beam LW. Specifically, for example, the wavelength of the laser light absorbed by the thin film 28 and the thickness of the thin film 28 are such that the absorption amount of the laser light LW in the thin film 28 is the absorption amount that allows the thin film 28 to generate heat up to a desired temperature. is set to be That is, the laser beam absorptivity of the thin film 28 is a value that allows the thin film 28 to rise to a desired temperature range by absorbing a portion of the laser beam LW.

Here, the gas inside the laser head 12 contains impurities. Impurities include minute liquids and solid particles. In general, when a gas containing impurities is irradiated with a laser beam, the impurities in the gas undergo an optical dust collection effect in which the impurities move toward the laser beam or the optical element irradiated with the laser beam. The higher the intensity of the laser beam, the greater the optical dust collection effect that the impurities receive. Also, when impurities are in a gas with a temperature gradient, the impurities are subject to thermophoretic forces that move from the high temperature side to the low temperature side. The thermophoretic force that the impurities receive increases as the temperature gradient between the high temperature side and the low temperature side increases.

By absorbing part of the laser beam LW, the thin film 28 exerts a thermophoretic force greater than the light dust collecting effect on the impurities contained in the gas inside the laser head 12 in the vicinity of the emission surface 23b. It is a configuration that raises the temperature as much as possible. That is, the above-mentioned "desired temperature" is a temperature at which a temperature gradient can be formed in the vicinity of the exit surface 23b so as to exert a thermophoretic force greater than the optical dust collecting effect on impurities drifting in the vicinity of the exit surface 23b. be. For example, the thin film body 28 absorbs a part of the laser beam LW and generates heat, so that the temperature is several degrees higher than the room temperature of the place where the laser processing apparatus 10 is arranged, for example, about 5 degrees Celsius higher. be. It is preferable that the thin film 28 does not generate enough heat to raise the ambient temperature of the laser light source 22, for example, the temperature of the entire interior of the laser head 12, even if it absorbs part of the laser beam LW. Further, the thin film body 28 is configured so as not to generate heat to a temperature higher than the heat-resistant temperature of the optical window 23 even if part of the laser beam LW is absorbed.

The thin film 28 is included in the antireflection film 26, for example. When the thin film body 28 is included in the antireflection film 26, the thin film body 28 is formed by vapor deposition when the antireflection film 26 is formed by vapor deposition. Therefore, the thin film body 28 is laminated on the surface of the substrate 27 together with a plurality of thin films forming the antireflection film 26 . The thin film body 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.

When the thin film body 28 is included in the antireflection film 26 , the thin film body 28 may be laminated so as to be adjacent to any thin film among the plurality of thin films that constitute the antireflection film 26 . For example, the antireflection film 26 has a thin film different from the thin film 28 in the first layer that contacts the air around the optical window 23 , and a second layer adjacent to the first layer is the thin film 28 . A third layer that is aligned with and adjacent to the surface of the substrate 27 may be a thin film different from the thin film body 28 . In this case, the first layer and the third layer may be composed of only one thin film, or may be composed of a plurality of laminated thin films. Further, for example, the antireflection film 26 has a thin film body 28 as a first layer in contact with the air around the optical window 23 and a thin film body 28 as a second layer adjacent to the first layer and adjacent to the surface of the substrate 27 . It may be a configuration that is a thin film different from. In this case, the second layer has a structure in which a plurality of thin films are laminated. Further, for example, the antireflection film 26 is composed of a thin film whose first layer that contacts the air around the optical window 23 is different from the thin film 28, and a second layer that is adjacent to the first layer and adjacent to the surface of the substrate 27. may be the thin film body 28 . In this case, the first layer has a structure in which a plurality of thin films are laminated.

Also, the wavelength of the laser light with 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 that passes through the optical window 23 . More preferably, the wavelength of the laser light with the highest absorptivity in the thin film 28 is the flat part as far as possible from the peak of the spectrum of the laser light LW passing through the optical window 23 having the thin film 28. Set to wavelength. When there are multiple peaks on the spectrum of the same laser beam LW, the wavelength of the laser beam with the highest absorption rate in the thin film 28 should be as flat as possible in a portion distant from the peak or maximum point, that is, from the peak. It is preferable to set the wavelength of the remote, non-steep portion.

In the thin film body 28, the material (material), the absorption wavelength, and the stacking order of the antireflection film 26 are selected so that a thermophoretic force greater than the light dust collection effect can be exerted on the impurities in the vicinity of the output surface 23b. etc. is set.

[Configuration of laser head 12]
As shown in FIG. 1, the laser head 12 has, for example, a beam expander 31, a focus adjustment section 32, a scanning section 33, and a protective glass . The laser head 12 has a housing 35 . The beam expander 31 , focus adjustment section 32 and scanning section 33 are housed inside a housing 35 .

[Configuration of beam expander 31]
The beam expander 31 is arranged between the laser light source 22 and the scanning section 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 multiple optical elements. For example, the beam expander 31 has two lenses, a first lens 41 into which the laser light LW is incident and a second lens 42 into 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 that constitutes an optical system in the laser processing apparatus 10 . That is, the beam expander 31 may have two optical elements.

The first lens 41 on the incident side in the beam expander 31 is, for example, a concave lens. A second lens 42 on the output side of the beam expander 31 is a convex lens. Both the first lens 41 and the second lens 42 may be convex lenses. The beam expander 31 expands the beam diameter of the incident laser light LW by a magnification according to the distance between the first lens 41 and the second lens 42, and emits 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 .

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

The first lens 41 has an incident surface 41a on which the laser beam LW is incident and an output surface 41b from which the laser beam LW is emitted. The entrance surface 41 a and the exit surface 41 b are part of the surface of the first lens 41 . The incident surface 41 a is exposed outside the housing 43 , that is, inside the laser head 12 . The exit surface 41 b is exposed inside the housing 43 . The second lens 42 has an incident surface 42a on which the laser beam LW transmitted through the first lens 41 is incident, and an output surface 42b from which the laser beam LW is emitted. The entrance surface 42 a and the exit surface 42 b are part of the surface of the second lens 42 . The incident surface 42 a is exposed inside the housing 43 . The exit surface 42 b is exposed to the outside of the housing 43 .

The first lens 41 has an antireflection film 45 on the incident surface 41a. The first lens 41 also has an antireflection film 46 on the exit surface 41b. That is, the first lens 41 has antireflection

films

45 and 46 on the surface of the first lens 41 . The second lens 42 has an antireflection film 47 on the incident surface 42a. The second lens 42 also has an antireflection film 48 on the exit surface 42b. That is, the second lens 42 has antireflection

films

47 and 48 on the surface of the second lens 42 .

The first lens 41 has a base material 51 . The base material 51 is, for example, a glass substrate similar to the base material 27 . The

antireflection films

45 and 46 are integrally formed on the surface of the base material 51 . Each of the

antireflection films

45 and 46 is a multilayer film composed of a plurality of thin films of materials such as oxides, metals, and rare earth elements, similar to the

antireflection films

25 and 26 . Each of the

antireflection films

45 and 46 may have the same structure as the antireflection film 25 or the antireflection film 26, or may have a different structure. Each of the

antireflection films

45 and 46 is integrally formed on the surface of the substrate 51 by vapor deposition.

The second lens 42 has a base material 52 . The base material 52 is, for example, a glass substrate similar to the base material 51 . The

antireflection films

47 and 48 are integrally formed on the surface of the base material 52 . Each of the

antireflection films

47 and 48 is a multilayer film composed of a plurality of thin films of materials such as oxides, metals and rare earth elements, similar to the

antireflection films

45 and 46 . Each of the

antireflection films

47 and 48 may have the same configuration as the antireflection film 46, or may have a different configuration. Each of the

antireflection films

47 and 48 is integrally formed on the surface of the base material 52 by vapor deposition.

For example, the first lens 41 has a thin film body 53 that is integrally provided in a portion of the first lens 41 that transmits the laser beam LW and absorbs part of the laser beam LW. The thin film body 53 is provided integrally with the incident surface 41a of the first lens 41, for example. The first lens 41 has, for example, a thin film 53 over at least the entire range irradiated with the laser beam LW on the incident surface 41a. That is, the thin film 53 is provided at least on the incident surface 41a over the entire beam diameter range of the laser beam LW when the incident surface 41a is irradiated with the laser beam LW. In one example, the thin film body 53 is not provided in a region of the incident surface 41a of the first lens 41 other than the range irradiated with the laser beam LW. Alternatively, the first lens 41 may have a thin film 53 over the entrance surface 41a.

The thin film body 53 has the same configuration as the thin film body 28 that the optical window 23 has. That is, the thin film body 53 absorbs a part of the laser beam LW, so that the impurity contained in the gas inside the laser head 12 exerts a thermophoretic force larger than the light dust collection effect near the incident surface 41a. It is a configuration that raises the temperature as much as possible.

The thin film body 53 is included in the antireflection film 45, for example. When the thin film body 53 is included in the antireflection film 45, the thin film body 53 is formed by vapor deposition when the antireflection film 45 is formed by vapor deposition. Therefore, the thin film body 53 is laminated on the surface of the base material 51 together with a plurality of thin films forming 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 body 53 is included in the antireflection film 45 , the thin film body 53 is adjacent to any of the thin films constituting the antireflection film 45 in the same manner as the thin film body 28 included in the antireflection film 26 . may be laminated as follows.

Also, the wavelength of the laser light with 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 that passes through the first lens 41 having the thin film 53 . More preferably, the wavelength of the laser light with the highest absorptivity in the thin film 53 is the flat part as far as possible from the peak of the spectrum of the laser light LW that passes through the first lens 41 having the thin film 53. set to the wavelength of When a plurality of peaks exist on the spectrum of the same laser beam LW, the wavelength of the laser beam with the highest absorption rate in the thin film 53 should be the flattest portion apart from the peak or the maximum point, that is, from the peak. It is preferable to set the wavelength of the remote, non-steep portion.

In the thin film 53, the material (material), the absorption wavelength, and the stacking order of the antireflection film 45 are selected so that a thermophoretic force greater than the light dust collection effect can be applied to the impurities in the vicinity of the incident surface 41a. etc. is set.

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 expander 31 expands the beam diameter of the laser light LW than after the beam expander 31 expands the beam diameter of the laser light LW. Therefore, the optical window 23 and the first lens 41 are arranged at a place where the intensity of the laser beam LW is high.

[Configuration of focus adjustment unit 32]
The focus adjustment section 32 has a lens section 61 and a driving section 62 . Lens portion 61 includes at least two lenses. The lens is an optical element that constitutes an optical system in the laser processing apparatus 10 . Each lens is arranged on the optical path of the laser beam LW. At least one lens included in the lens portion 61 is supported by a support member (not shown) such as a linear slider so as to be movable along the passage path of the laser light LW. Under the control of the control unit 21, the drive unit 62 moves the movably supported lens along the passage path of the laser light LW. Thereby, the focus adjustment unit 32 adjusts the focal position of the laser beam LW.

[Configuration of scanning unit 33]
The scanning unit 33 has galvanometer mirrors 63X and 63Y and a driving unit 64 .

Galvanomirrors

63X and 63Y reflect the laser beam LW. Each of the

galvanomirrors

63X and 63Y is an optical element that constitutes an optical system in the laser processing apparatus 10. As shown in FIG. The drive unit 64 rotates the

galvanomirrors

63X and 63Y. The drive unit 64 is, for example, a motor. The driving section 64 is controlled by the control section 21 . The

galvanomirrors

63X and 63Y and the drive unit 64 are configured to scan the laser light LW in two-dimensional directions. For example, the galvanomirror 63X and the drive unit 64 scan the laser light LW in the X-axis direction. Also, for example, the galvanomirror 63Y and the drive unit 64 scan the laser light LW in the Y-axis direction.

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

[Action of Embodiment]
The operation of this embodiment will be described.
In laser processing apparatus 10 , laser light source 22 emits laser light LW from optical window 23 . The laser light LW emitted through the optical window 23 enters 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 beam LW emitted from the second lens 42 is applied to the workpiece W through the lens portion 61 of the focus adjustment portion 32 , the galvanometer mirrors 63 X and 63 Y of the scanning portion 33 , and the protective glass 34 . The workpiece W can be processed by this laser beam LW.

In the laser processing apparatus 10 , a thin film 28 that partially absorbs the laser beam LW is provided on the emission surface 23 b of the optical window 23 exposed inside the laser head 12 . A thin film 53 that absorbs part of the laser beam LW is provided on the incident surface 23a of the first lens 41 exposed inside the laser head 12 .

When the laser light source 22 emits the laser beam LW, the thin film 28 of the optical window 23 absorbs part of the laser beam LW and generates heat. Specifically, the portion of the thin film 28 through which the laser beam LW passes generates heat. Therefore, the temperature of the exit surface 23b of the optical window 23 provided with the thin film 28 rises. Then, the heat of the thin film 28 is transferred to the air in the vicinity of the portion of the emission surface 23b through which the laser beam LW passes. Therefore, the temperature rises locally in the vicinity of the portion of the emission surface 23b through which the laser beam LW passes. Then, a temperature difference occurs between the portion of the thin film 28 to which the heat is transmitted and the portion of the thin film 28 surrounding the portion to which the heat is not transmitted. By creating such a temperature difference, a thermophoretic effect can be produced on impurities drifting in the heat-transferred portion of the thin film 28 in the vicinity of the exit surface 23b. Impurities floating in the heat-transferred portion of the thin film 28 in the vicinity of the output surface 23b are subject to thermophoretic force moving from the high temperature side to the low temperature side, that is, the thermophoretic force moving away from the output surface 23b.

The thin film 28 that has absorbed a part of the laser beam LW has a light dust collection effect that the thermophoretic force acting on the impurity near the emission surface 23b acts on the impurity by irradiating the inside of the laser head 12 with the laser beam LW. It generates enough heat to generate a temperature gradient in the vicinity of the output surface 23b. Therefore, impurities drifting in the vicinity of the output surface 23b are subjected to a thermophoretic force greater than the optical dust collection effect. Therefore, impurities drifting in the vicinity of the exit surface 23b move away from the exit surface 23b. Therefore, it is possible to prevent impurities drifting inside the laser head 12 from adhering to the emission surface 23b.

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 part of the laser light LW, similar to the thin film 28 . Like the impurities drifting near the exit surface 23b, the impurities drifting near the entrance surface 41a of the first lens 41 receive a thermophoretic force greater than the optical dust collection effect. Therefore, impurities floating in the vicinity of the incident surface 41a move away from the incident surface 41a. Therefore, it is possible to prevent impurities drifting inside the laser head 12 from adhering to the incident surface 41a.

[Effects of Embodiment]
Effects of the present embodiment will be described.
(1) The laser processing apparatus 10 includes a laser light source 22 that emits a laser beam LW for processing the object W to be processed. In addition, the laser processing apparatus 10 has a scanning unit 33 for scanning the laser beam LW emitted from the laser light source 22, a laser head 12 for irradiating the workpiece W with the laser beam LW, the laser light source 22 and the scanning and a control unit 21 that controls the 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 beam LW. The optical window 23 has a thin film body 28 that is integrally provided in a portion of the optical window 23 that transmits the laser beam LW and that absorbs part of the laser beam LW. The first lens 41 has a thin film body 53 that is integrally provided in a portion of the first lens 41 that transmits the laser beam LW and absorbs part of the laser beam LW.

According to this configuration, the

thin films

28 and 53 generate heat by absorbing part of the laser beam LW. The heat of the

thin films

28 and 53 can act on the impurities floating in the gas near the

thin films

28 and 53 with a thermophoretic force greater than the optical dust collection effect. This thermophoretic force causes the impurities to move away from the

thin films

28 and 53 . That is, the impurities move away from the optical window 23 and the first lens 41 . Therefore, it is possible to prevent impurities from adhering to the optical window 23 and the first lens 41 while the laser light source 22 is emitting the laser light LW. As a result, it is possible to suppress a decrease in the laser output of the laser beam LW emitted from the laser head 12 toward the object W to be processed.

In addition, the laser processing apparatus 10 requires maintenance such as cleaning and replacement of built-in optical elements. In this embodiment, the adhesion of impurities to the optical window 23 and the first lens 41 is reduced, so maintenance intervals for the optical window 23 and the first lens 41 can be lengthened.

(2) The optical window 23, which is one of the optical elements forming the optical system in the laser processing apparatus 10, has an antireflection film 26 on its surface. A thin film 28 included in the optical window 23 is included in the antireflection film 26 . Also, the first lens 41, which is one of the optical elements forming the same optical system, has an antireflection film 45 on its surface. The thin film 53 of the first lens 41 is included in the antireflection film 45 .

For example, the antireflection film 26 has a thin film different from the thin film 28 in the first layer that contacts the air around the optical window 23 , and a second layer adjacent to the first layer is the thin film 28 . In some cases, the third layer, which is aligned with and adjacent to the surface of the substrate 27, is a thin film different from the thin film . Further, for example, the antireflection film 26 has a thin film body 28 as a first layer in contact with the air around the optical window 23 and a thin film body 28 as a second layer adjacent to the first layer and adjacent to the surface of the substrate 27 . In some cases, the configuration may be a thin film different from the Further, for example, the antireflection film 26 is composed of a thin film whose first layer that contacts the air around the optical window 23 is different from the thin film 28, and a second layer that is adjacent to the first layer and adjacent to the surface of the substrate 27. is the thin film 28 in some cases. The same is true for the antireflection film 45 including the thin film 53 .

It goes without saying that these

thin films

28 and 53 are selected so as to be able to exert a thermophoretic force on impurities that is greater than the light dust collecting effect in the vicinity of each of the

thin films

28 and 53 .

According to this configuration, the thin film body 28 can be formed in the same manner as the plurality of thin films forming the antireflection film 26, so that the thin film body 28 can be easily formed. In addition, the thin film 28 is less likely to peel off from the surface of the optical window 23 than, for example, when the thin film 28 is formed by coating the surface of the optical window 23 with a material forming the thin film 28 . The thin film 53 of the first lens 41 also has the same effect.

(3) The optical window 23 and the first lens 41 transmit the laser light LW in the near-infrared region. The thin film 28 of the optical window 23 and the thin film 53 of the first lens 41 are zinc oxide thin films.

According to this configuration, each of the

thin films

28 and 53 can easily absorb part of the laser light LW in the near-infrared region.
(4) The laser head 12 has a beam expander 31 arranged 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 multiple optical elements. One optical element among the plurality of optical elements is the first lens 41 on which the laser beam LW is incident, and one optical element different from the first lens 41 among the plurality of optical elements is the first lens 41 is the second lens 42 into which the laser beam LW transmitted through is incident. The first lens 41 has a thin film body 53 .

According to this configuration, the first lens 41 on the incident side transmits laser light LW having a smaller beam diameter than the second lens 42 on the emitting side. Therefore, the intensity of the laser light LW is higher when passing through the first lens 41 than when passing through the second lens 42 . Therefore, the optical dust collection effect of impurities drifting in the vicinity of the first lens 41 is greater than the optical dust collection effect of impurities floating in the vicinity of 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, the first lens 41 having the thin film 53 can suppress the adhesion of impurities to the first lens 41, which is highly likely to be contaminated with impurities. Since the first lens 41, which is an optical element more likely to be contaminated with impurities, has the thin film 53, the laser output of the laser light LW emitted from the laser head 12 toward the workpiece W is reduced. It is possible to more effectively suppress the decrease.

(5) The laser light source 22 has an optical window 23 for emitting the laser light LW. The optical window 23 is one of optical elements forming an optical system in the laser processing apparatus 10 . The optical window 23 has an incident surface 23a on which the laser beam LW is incident and an output surface 23b from which the laser beam LW is emitted. A thin film 28 is provided on the output surface 23b.

According to this configuration, the thin film body 28 is provided on the emission surface 23b exposed inside the laser head 12 . The gas inside the laser head 12 contains impurities. Therefore, there is concern that impurities may adhere to the emission surface 23b exposed inside the laser head 12 due to the photophoresis effect when the laser light source 22 emits the laser light LW. Therefore, by providing the thin film 28 on the exit surface 23b, the adhesion of impurities to the exit surface 23b can be suppressed by the thermophoretic effect.

Also, the laser light LW transmitted 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 transmitted 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 received by impurities floating in the vicinity of the optical window 23 is greater than the optical dust collection effect caused by the laser light LW emitted from the beam expander 31 . Therefore, if the optical window 23 does not have the thin film 28, impurities are more likely to adhere to the optical window 23 than to an optical element that transmits or reflects the laser beam LW whose beam diameter has been expanded by the beam expander 31. Therefore, by providing the optical window 23 with the thin film 28, it is possible to suppress the adhesion of impurities to the optical window 23, which is highly likely to be contaminated with impurities. Since the optical window 23, which is an optical element more susceptible to the attachment of impurities, has the thin film 28, the laser output of the laser light LW emitted from the laser head 12 toward the workpiece W is reduced. can be more effectively suppressed.

(6) The optical window 23 has an incident surface 23a on which the laser beam LW is incident and an output surface 23b from which the laser beam LW is emitted. The optical window 23 has a thin film 28 over at least the entire range through which the laser beam LW passes on one of the incident surface 23a and the exit surface 23b. Further, the first lens 41 has an incident surface 41a on which the laser beam LW is incident and an output surface 41b from which the laser beam LW is emitted. The first lens 41 has a thin film 53 over at least the entire range irradiated with the laser beam LW on one of the entrance surface 41a and the exit surface 41b.

When the optical window 23 does not have the thin film 28, the range through which the laser beam LW passes on the exit surface 23b of the optical window 23 is the impurity caused by the optical dust collection effect caused by the laser beam LW in the vicinity of the exit surface 23b. is the part where it is easy to adhere. Similarly, when the first lens 41 does not have the thin film 53, the range irradiated with the laser beam LW on the incident surface 41a receives the optical dust collection effect caused by the laser beam LW in the vicinity of the incident surface 41a. This is a portion where impurities tend to adhere. Further, when impurities adhere to the range through which the laser beam LW passes on the exit surface 23b of the optical window 23, the laser head 12 emits light from the laser head 12 toward the workpiece W more than when the impurities adhere to the outside of the range. It tends to affect the laser output of the laser light LW. Similarly, when impurities adhere to the range irradiated with the laser beam LW on the incident surface 41a of the first lens 41, the distance from the laser head 12 to the workpiece W increases as compared with the case where the impurities adhere to the outside of the range. This tends to affect the laser output of the laser light LW emitted by the laser beam LW. Therefore, since the optical window 23 has the thin film 28 over at least the entire range through which the laser beam LW passes on the output surface 23b, the laser output of the laser beam LW emitted from the laser head 12 toward the workpiece W can be reduced. The decrease can be suppressed more effectively. In addition, since the first lens 41 has the thin film 53 over at least the entire range irradiated with the laser beam LW on the incident surface 41a, the laser beam LW emitted from the laser head 12 toward the workpiece W A decrease in output can be suppressed more effectively.

(7) The wavelength of the laser light with the highest absorption rate in the thin film 28 is a wavelength different from the peak wavelength of the spectrum of the laser light LW that passes through the optical window 23 having the thin film 28 . More preferably, the wavelength of the laser light with the highest absorptivity in the thin film 28 is the flat part as far as possible from the peak of the spectrum of the laser light LW passing through the optical window 23 having the thin film 28. Set to wavelength. When there are multiple peaks on the spectrum of the same laser beam LW, the wavelength of the laser beam with the highest absorption rate in the thin film 28 should be as flat as possible in a portion distant from the peak or maximum point, that is, from the peak. It is preferable to set the wavelength of the remote, non-steep portion.

The wavelength of the laser light with the highest absorption rate in the thin film 53 is different from the peak wavelength of the spectrum of the laser light LW that passes through the first lens 41 having the thin film 53 . More preferably, the wavelength of the laser light with the highest absorptivity in the thin film 53 is the flat part as far as possible from the peak of the spectrum of the laser light LW that passes through the first lens 41 having the thin film 53. set to the wavelength of When a plurality of peaks exist on the spectrum of the same laser beam LW, the wavelength of the laser beam with the highest absorption rate in the thin film 53 should be the flattest portion apart from the peak or the maximum point, that is, from the peak. It is preferable to set the wavelength of the remote, non-steep portion.

It goes without saying that these

thin films

28 and 53 .

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 the laser output of the laser processing apparatus 10 can be prevented from decreasing.
(8) In the present embodiment, it is not necessary to airtightly house optical elements, such as the optical window 23 and the first lens 41, for which adhesion of impurities is desired to be suppressed. Therefore, it is not necessary to place a dehumidifying agent for preventing dew condensation in the space where the optical window 23 and the first lens 41 are arranged, or to replace the dehumidifying agent. Therefore, it is possible to prevent impurities from adhering to the optical window 23 and the first lens 41 without increasing the maintenance burden of the laser processing apparatus 10 .

(9) By locally raising the temperature of the surface of the optical element whose adhesion of impurities is to be suppressed, for example, the optical window 23 and the first lens 41 by the heat generated by the

thin films

28 and 53, the optical window 23 and the first lens 41 It suppresses the adhesion of impurities to the surface of the Therefore, it is not necessary to entirely heat the part holding the optical window 23 with a heater or entirely heat the part holding the first lens 41 with a heater. Therefore, it is difficult for a wide range inside the laser light source 22 to reach a high temperature, or for a wide range inside the laser head 12 to rise to a high temperature. Therefore, even if the operating temperature of the laser light source 22 and the operating temperature of the laser head 12 are not considered, it is possible to prevent impurities from adhering to the optical window 23 and the first lens 41 . Furthermore, it is possible to suppress the adhesion of impurities to the optical window 23 and the first lens 41 while suppressing an increase in the number of parts.

[Change example]
This embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

· In the above embodiment, among the plurality of optical elements forming the optical system in the laser processing apparatus 10, the optical window 23 and the first lens 41 have the

thin films

28 and 53, respectively. However, at least one of the plurality of optical elements constituting the optical system in the laser processing apparatus 10 is integrally provided in a portion of the optical element that transmits or reflects the laser beam LW. It is only necessary to have a thin film that absorbs part of the 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 . Further, for example, optical elements other than the optical window 23 and the first lens 41 may have thin films. For example, the second lens 42 may have the thin film 53 . Further, for example, each of the

galvanomirrors

63X and 63Y that reflect the laser light LW may have a thin film. In each of the

galvanomirrors

63X and 63Y, the incident surface into which the laser beam LW is incident and the exit surface from which the laser beam LW is emitted are the same surface. Incidentally, an optical element on the optical path having the same beam diameter of the laser light LW, for example, parallel light from the optical window 23 to the first lens 41 and diffused light from the first lens 41, the optical window 23 and , the first lens 41 preferably has a thin film on at least the side of the incident surface 41a. In one example, the at least one optical element that transmits or reflects laser light is an optical element (eg, first lens 41) disposed within housing 35 of laser head 12 and/or housing 35 of laser head 12. includes an optical element (eg, optical window 23) exposed to the interior of the . In one example, at least one optical element that transmits or reflects laser light is arranged in the transmission path of the laser light LW between the laser light source 22 and the scanning section 33 .

Further, for example, in the laser processing apparatus 10, all the optical elements that are arranged on the optical path of the laser beam LW and that transmit or reflect the laser beam LW have a thin film that partially absorbs the laser beam LW. may By doing so, it is possible to prevent impurities from adhering to all the optical elements.

- The optical window 23 may have the thin film 28 only in a range through which the laser light LW passes on at least one of the entrance surface 23a and the exit surface 23b. Further, the optical window 23 may have a thin film 28 in a part of the range through which the laser light LW passes on at least one of the entrance surface 23a and the exit surface 23b.

Similarly, the first lens 41 may have the thin film 53 only in the range irradiated with the laser light LW on at least one of the entrance surface 41a and the exit surface 41b. Further, the first lens 41 may have a thin film 53 in part of the range irradiated with the laser light LW on at least one of the entrance surface 41a and the exit surface 41b.

- A thin film 28 may be provided on the incident surface 23 a of the optical window 23 .
- As for the 1st lens 41, the thin film body 53 may be provided in each of the entrance surface 41a and the output surface 41b. By doing so, it is possible to 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 closed type, there is concern that impurities may also adhere to the output surface 41b. In this case, if the thin film 53 is provided on the emission surface 41b, the adhesion of the impurities to the emission surface 41b can be suppressed.

- In addition to the 1st lens 41 and the 2nd lens 42, the beam expander 31 may have 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-based thin film. The thin film may be made of a material other than the zinc oxide-based material as long as it can absorb part of the laser light LW.

· The laser light source 22 may emit laser light LW including wavelengths 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 wave 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 wave having a higher frequency than the second harmonic wave (THG: Third Harmonic Generation). The wavelength of the third harmonic is in the ultraviolet region, eg, 355 nm.

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 range. Also, the

galvanomirrors

63X and 63Y reflect the laser light LW in the ultraviolet region. At least one of the optical elements that transmit or reflect the laser light LW in the ultraviolet region is a thin film body that is a titanium oxide (TiO ₂ )-based thin film that absorbs a part of the laser light LW in the ultraviolet region. may have. For example, the

thin films

28 and 53 of the optical window 23 and the first lens 41 are titanium oxide thin films. By doing so, 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 prevent impurities from adhering to the optical window 23 and the first lens 41 .

In this case, if the optical element of the laser oscillator and the wavelength conversion element that generates the second harmonic have a thin film, the thin film is preferably a zinc oxide (ZnO)-based thin film.

· The laser processing apparatus 10 may include an optical element having a high reflection film (HR coat). The optical element may have a thin film on its surface that absorbs part of the laser beam LW. In this case, the thin film may be included in the reflection enhancing film. In this way, the thin film body can be formed in the same manner as the plurality of thin films forming the reflection enhancing film, so that the thin film body can be easily formed. In addition, the thin film is less likely to peel off from the surface of the optical element than, for example, when the thin film is formed by coating the surface of the optical element with a material forming the thin film.

· As shown in FIG. 3, the thin film 28 may not be included in the antireflection film 26 . In the example shown in FIG. 3, the optical window 23 has an antireflection film 25 that does not include the thin film 28 on each of the entrance surface 23a and the exit surface 23b. The thin film body 28 is integrally provided on the surface of the antireflection film 25 . For example, the thin film 28 is provided integrally with the optical window 23 by coating the surface of the antireflection film 25 after the antireflection film 25 is formed on the surface of the substrate 27 . The surface of the antireflection film 25 is the surface of the antireflection film 25 opposite to the substrate 27 . In the example shown in FIG. 3, the thin film body 28 is provided on each of the entrance surface 23a and the exit surface 23b. good too. The thin film 53 included in the first lens 41 may be similarly formed.

· As shown in FIG. 4 , the optical window 23 may have a thin film 71 instead of the thin film 28 . The thin film body 71 is integrally provided on the surface of the antireflection 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 body 71 has, on the surface of the thin film body 71, an uneven structure portion 72 having a large number of fine unevenness that absorbs the laser light LW. Each concave portion and each convex portion in the concave-convex structure portion 72 has a nanometer-order size. In this way, part of the laser beam LW can be absorbed in the concave-convex structure portion 72 . Therefore, the same effect as (1) of the above embodiment can be obtained. In the example shown in FIG. 4, the thin film body 71 is provided on each of the entrance surface 23a and the exit surface 23b, but the thin film body 71 is provided only on one of the entrance surface 23a and the exit surface 23b. may be

Further, the uneven structure portion 72 may be provided on the surface of the antireflection film 25 . In this case, the antireflection film 25 having the uneven structure portion 72 corresponds to a thin film that partially absorbs the laser light LW.
- All features disclosed in the specification and/or claims are for the purposes of the original disclosure and claimed independently of any combination of features in the embodiments and/or claims. They are intended to be disclosed separately and independently of each other for the purpose of limiting the scope of the invention. Statements representing all numerical ranges or collections of elements are for the purposes of the initial disclosure and for the purposes of limiting the claimed invention, and specifically as limitations on numerical ranges, all possible Intermediate values or intermediate components are disclosed.

10 laser processing device 11 laser emission unit 12 laser head (laser irradiation unit)
21 control unit 22 laser light source 23 optical window

23a entrance surface

23b exit surface 25 antireflection film 26 antireflection film 27 base material 28 thin film body 31 beam expander 32 focus adjustment unit 33 scanning unit 34 protective glass 35 housing 35a opening 41 th 1 lens 41a entrance surface 41b exit surface 42 second lens 42a entrance surface 42b exit surface 43 housing 45 antireflection film 46

antireflection film

47, 48 antireflection film 51 base material 52 base material 53 thin film body 61 lens section 62

driving section

63X, 63Y Galvanomirror 64 Actuator 71 Thin film 72 Concavo-convex structure LW Laser beam W Object to be processed

Claims

a laser light source that emits laser light for processing an object;
a laser irradiation unit having a scanning unit for scanning the laser light emitted from the laser light source and irradiating the laser light onto the object to be processed;
a control unit that controls the laser light source and the scanning unit;
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,
The laser processing apparatus, wherein at least one of the optical elements has a thin film that is integrally provided in a portion of the optical element that transmits or reflects the laser beam and that absorbs part of the laser beam.
at least one optical element has an antireflection coating on its surface;
2. The laser processing apparatus according to claim 1, wherein said thin film is included in said antireflection film.
at least one of the optical elements has a reflection enhancing film on its surface;
3. The laser processing apparatus according to claim 1, wherein the thin film is included in the reflection-increasing film.
4. Any one of claims 1 to 3, wherein at least one optical element transmits or reflects the laser light in the ultraviolet region, and the thin film body included in the optical element is a titanium oxide-based thin film. 1. The laser processing apparatus according to claim 1.
At least one optical element transmits or reflects the laser light in the near-infrared region, and the thin film body included in the optical element is a zinc oxide-based thin film. The laser processing apparatus according to any one of items 1 to 3.
The laser irradiation unit has a beam expander arranged between the laser light source and the scanning unit to expand the 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 into which the laser beam is incident, and The one optical element different from the first lens is a second lens on which the laser beam 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 body.
The first lens has an incident surface on which the laser beam is incident and an exit surface from which the laser beam is emitted, and the incident surface of the first lens and the exit surface of the first lens each have the 7. The laser processing apparatus according to claim 6, wherein the thin film body is provided.
The laser light source has the optical element which is an optical window for emitting the laser light,
The optical window has an incident surface on which the laser light is incident and an output surface from which the laser light is emitted, and the thin film is provided on the output surface of the optical window. 8. The laser processing apparatus according to any one of 7.
The at least one optical element has an incident surface on which the laser light is incident and an output surface from which the laser light is emitted, and at least one of the incident surface of the optical element and the output surface of the optical element 9. The laser processing apparatus according to any one of claims 1 to 8, wherein the thin film body is provided over at least the entire range of the surface through which the laser beam is irradiated or passes.
The laser processing apparatus according to any one of claims 1 to 9, wherein all the optical elements that are arranged on the optical path of the laser beam and transmit or reflect the laser beam have the thin film body.
The wavelength of the laser light with the highest absorption rate in the thin film is a wavelength different from the peak wavelength of the spectrum of the laser light that is transmitted through the optical element having the thin film or reflected by the optical element having the thin film. The laser processing apparatus according to any one of claims 1 to 10, wherein: