TWI732427B - Optical member and laser processing machine - Google Patents

Abstract

The optical member (10) of this invention includes a substrate (1) and a multilayer film (7). The substrate (1) is made of germanium. The multilayer film (7) is laminated on the substrate (1). The multilayer film (7) is made by, from the substrate (1) side, at least three layers of: a ZnS film (4) that is a zinc compound film, a Ge film (5) that is a germanium film, and a DLC film (6) that is a diamond-like carbon film laminated in this order. The optical member (10) does not use oxide, and can transmit infrared light with high transmittance.

Description

Optical component and laser processing machine

The present invention relates to an optical component and a laser processing machine having the optical component.

A laser processing machine that processes a workpiece by irradiation with laser light is provided with a protective window that is an optical member for protecting a lens system including a condenser lens. The protective window protects the lens system from dust or spatters generated during processing. In the case of a laser processing machine using a carbon dioxide (CO ₂ ) laser as the laser light source, the protective window is required to have a high transmittance to _{the CO 2 laser light which is infrared light.} In addition, the protective window is required to have environmental resistance, which is the so-called abrasion resistance that can suppress damage when wiping off foreign matter attached to the protective window, and is not affected by the gas filled during laser processing. Corrosion resistance that produces corrosion.

Patent Document 1 discloses an optical member which has a substrate made of zinc sulfide (ZnS) and is laminated in order from the surface of the substrate: a first yttrium oxide (Y ₂ O ₃ ) film, and yttrium fluoride (YF ₃ ) A film, a second Y ₂ O ₃ film, a germanium (Ge) film, and a diamond-like carbon (Diamond Like Carbon: DLC) film. The optical member of Patent Document 1 has high environmental resistance by providing a DLC film on the surface of the optical member. In addition, in the optical member of Patent Document 1, the first Y ₂ O ₃ film and the second Y ₂ O ₃ film sandwich the YF ₃ film to ensure the adhesion between the substrate and the YF ₃ film and the DLC film.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2008-268277 A

However, in the optical member of Patent Document 1 mentioned above, there is a problem that the transmittance of infrared light is reduced due to the absorption of infrared light in _{the two Y 2} O _{3 films that are oxides.}

In view of the above-mentioned problems, the present invention aims to obtain an optical member that does not use oxides and can transmit infrared light with a high transmittance.

In order to solve the above-mentioned problems and achieve the objective, the optical member of the present invention includes a substrate and a multilayer film made of germanium. The multilayer film is composed of at least three layers laminated in the order of a zinc compound film, a germanium film, and a diamond-like carbon film from the substrate side.

According to the present invention, the optical member does not use oxides and can transmit infrared light with high transmittance.

1: substrate

2: first side

3: second side

4: ZnS film

4a: The first ZnS film

4b: Second ZnS film

5: Ge film

5a: First Ge film

5b: Second Ge film

6: DLC film

7, 9: Multilayer film

8: Anti-reflective film

10, 11, 12: optical components

20, 30: Laser processing machine

21: Laser oscillator

22: Laser light

23: Condenser lens

24: protection window

25: processed objects

31: lens barrel

Figure 1 is a cross-sectional view showing the configuration of the optical member of Embodiment 1 of the present invention.

FIG. 2 is a cross-sectional view showing another structure of the optical member of Embodiment 1. FIG.

FIG. 3 is a diagram showing an example of the wavelength dependence of the transmittance of the optical member in Embodiment 1. FIG.

Figure 4 is a graph showing the wavelength dependence of the transmittance of the optical member of the comparative example of Embodiment 1.

Fig. 5 is a cross-sectional view showing the structure of the optical member of Embodiment 2 of the present invention.

Fig. 6 is a diagram showing an example of the wavelength dependence of the transmittance of the optical member in the second embodiment.

Fig. 7 is a diagram showing a schematic configuration of a laser processing machine of Embodiment 3 of the present invention.

Fig. 8 is a diagram showing a schematic configuration of a laser processing machine according to Embodiment 4 of the present invention.

The optical component and the laser processing machine of the embodiment of the present invention will be described in detail below based on the drawings. In addition, the present invention is not limited to the following description, but can be appropriately changed within a range that does not deviate from the gist of the present invention. The scale of each part shown in the diagram may be different from the actual situation.

Implementation status 1.

Fig. 1 is a cross-sectional view showing the configuration of the optical member in Embodiment 1 of the present invention. The optical member 10 shown in FIG. 1 has a substrate 1 made of germanium, a multilayer film 7 provided on the first surface 2 belonging to the main surface of the substrate 1, and a substrate 1 and a first surface 2 provided in the substrate 1. It is the multilayer film 7 on the second side 3 on the opposite side. In addition, the substrate 1 made of germanium includes a germanium substrate containing a small amount of impurities. The main surface is the surface of the substrate 1 on the side from which light is emitted. Each multilayer film 7 series has There are three types of zinc compound films: ZnS film 4, Ge film 5, and DLC film 6. The Ge film 5 is provided between the ZnS film 4 and the DLC film 6.

The multilayer film 7 provided on the first surface 2 is composed of three layers laminated in the order of the ZnS film 4, the Ge film 5, and the DLC film 6 from the first surface 2 side. The DLC film 6 constitutes the outer surface of the optical member 10 on the side to which the first surface 2 of the substrate 1 faces.

The multilayer film 7 provided on the second surface 3 is composed of three layers laminated in the order of the ZnS film 4, the Ge film 5, and the DLC film 6 from the second surface 3 side. The DLC film 6 constitutes the outer surface of the optical member 10 on the side to which the second surface 3 of the substrate 1 faces.

Since DLC is a material with high hardness, the DLC film 6 can exhibit high wear resistance. In addition, since DLC is a substance with high stability and low reactivity with other substances, the DLC film 6 can exhibit high corrosion resistance. The DLC film 6 has low reactivity with other substances, and can weaken the adhesion of foreign matter such as dust. The optical member 10 becomes able to easily remove foreign matter adhering to the outer surface. The optical member 10 can obtain high environmental resistance by providing the DLC film 6 with excellent environmental resistance on the outer surface. The optical member 10 can be used for a long time by suppressing deterioration.

The optical member 10 can ensure the adhesion between the substrate 1 and the multilayer film 7 by bringing the DLC film 6 into contact with the Ge film 5 having excellent adhesion to the DLC film 6. The optical member 10 can suppress the peeling of the DLC film 6 caused by the compressive stress of the DLC film 6.

The adhesion between the Ge film 5 and the ZnS film 4 is also excellent. The optical member 10 can ensure the adhesion between the substrate 1 and the multilayer film 7 by contacting the Ge film 5 with the ZnS film 4. In addition, the optical member 10 may have a zinc compound film other than the ZnS film 4 instead of the ZnS film 4. The optical component 10 may also have a zinc selenide (ZnSe) film which is a zinc compound film other than the ZnS film 4. When the ZnSe film is provided, the excellent adhesion between the Ge film 5 and the ZnSe film can ensure the adhesion between the substrate 1 of the optical member 10 and the multilayer film 7. As long as it does not affect the optical performance of the optical member 10, the zinc compound film may be doped with elements other than Zn, S, and Se.

Ge has a high transmittance to the light system in the infrared region. By having the substrate 1 made of Ge, the optical member 10 can transmit infrared light with high transmittance. In addition, the substrate 1 made of Ge has a higher thermal conductivity than a substrate made of ZnS.

In the case where the optical member 10 is used in the protective window of a laser processing machine, when the laser processing machine is used for continuous laser processing, the lower the thermal conductivity of the substrate 1, the lower the thermal conductivity of the optical member 10 The more likely it is to produce a localized temperature rise. The lower the thermal conductivity of the optical member 10 based substrate 1 is, the more likely it is to generate a thermal lens effect due to temperature distribution. Since the refractive index distribution due to the thermal lens effect is generated in the optical component 10, it becomes difficult for the laser processing machine to perform high-precision processing. The optical member 10 includes the substrate 1 made of Ge with high thermal conductivity, so that the thermal lens effect can be suppressed. Thereby, the laser processing machine having the optical member 10 can suppress the generation of the refractive index distribution in the optical member 10, and it becomes possible to perform processing with high processing accuracy. If it does not affect the optical performance of the optical member 10 or the mechanical characteristics of the laser processing machine, the substrate 1 may be doped with elements other than Ge. The same is true for the layers constituting the multilayer film 7. If it does not affect the optical performance of the optical member 10 or the mechanical characteristics of the laser processing machine, the layers constituting the multilayer film 7 may also be doped with crystals that form the layer. Elements other than elements.

The shape of the substrate 1 may be any shape. In the case of the optical member 10 belonging to the protective window of the laser processing machine, from the point of view of the processing area of the laser processing machine, the substrate 1 The appropriate shape is a circular plate with a diameter of 80 mm to 120 mm. In addition, from the viewpoint of film stress, the thickness of the substrate 1 is appropriately 2 mm to 10 mm.

The method of forming the multilayer film 7 may be a method capable of forming the ZnS film 4, the Ge film 5, and the DLC film 6 on the substrate 1, and it is not limited to any method. For the formation of the multilayer film 7, the so-called physical vapor deposition (Physical Vapor Deposition: PVD) of the so-called vacuum vapor deposition method and the sputtering method, and the chemical vapor deposition of the so-called plasma CVD (Chemical Vapor Deposition) method can be used. Generally known film forming methods.

In the multilayer film 7, the thickness of the ZnS film 4 is set to be in the range of 600nm to 1000nm, the thickness of the Ge film 5 is set to be in the range of 10nm to 70nm, and the thickness of the DLC film 6 is set to be in the range of 50nm to 300nm. . Thereby, the optical member 10 can utilize the effect caused by the interference of light, and transmit infrared light with a high transmittance. The optical member 10 is provided with a substrate 1 made of Ge and a multilayer film 7 whose thickness of each layer is set within the above-mentioned range, and can achieve a transmittance of 97% or more for _{CO 2 laser light having a wavelength of 9 μm to 11 μm.} Thereby, the optical member 10 can satisfy the optical characteristics necessary for the protective window of the laser processing machine.

If it does not affect the optical performance of the optical member 10 or the mechanical characteristics of the laser processing machine, the optical member 10 may be provided with layers other than the layers shown in FIG. 1. In addition, if the optical member 10 is provided with a multilayer film 7 in the first surface 2 of the first surface 2 and the second surface 3, a film other than the multilayer film 7 may be provided in the second surface 3 to replace it. Multilayer film 7.

FIG. 2 is a cross-sectional view showing other configurations of the optical member of Embodiment 1. FIG. The optical member 11 shown in FIG. 2 includes an anti-reflection film 8 provided on the second surface 3 of the substrate 1. The anti-reflection film 8 is formed by _{stacking a YF 3} film, a Ge film, and a magnesium fluoride (MgF ₂ ) film in this order from the second surface 3. In FIG. 2, the illustration of each layer constituting the anti-reflection film 8 is omitted. However, the structure of the anti-reflection film 8 is not limited to this modification, and it may be one having an anti-reflection function.

In the optical member 11, an anti-reflection film 8 is provided on the second surface 3 of the substrate 1 on the side on which light is incident, thereby suppressing the reflection of the light incident on the optical member 11. In the case where the optical member 11 is used as a protective window of a laser processing machine, the optical member 11 is able to bear the DLC film 6 by providing the DLC film 6 on the outer surface of the object to be processed in the optical member 11 High environmental resistance to the environment during laser processing.

The method of forming the anti-reflection film 8 may be a method capable of forming each layer of the anti-reflection film 8 on the substrate 1, and it is not limited to any method. For the formation of the anti-reflection film 8, generally known film forming methods such as the so-called vacuum vapor deposition method and physical vapor deposition of the sputtering method, and chemical vapor deposition of the so-called plasma CVD method can be used.

Next, Embodiment 1 which is a specific example of Embodiment Mode 1 will be described. The optical component of Example 1 is an optical component 11 having a multilayer film 7 and an anti-reflection film 8, wherein the multilayer film 7 is provided on the first surface 2, and the anti-reflection film 8 is provided on the second surface 3. The anti-reflection film 8 has a transmittance of 99.5% or more for _{the CO 2 laser system having a wavelength of 9.3 μm.}

In the anti-reflection film 8 of Example 1, _{the thickness of the MgF 2} film was set to 200 nm, the thickness of the Ge film was set to 130 nm, and _{the thickness of the YF 3} film was set to 650 nm. In the multilayer film 7, the thickness of the ZnS film 4 is 800 nm, the thickness of the Ge film 5 is 30 nm, and the thickness of the DLC film 6 is 200 nm. The ZnS film 4, the Ge film 5, and the anti-reflection film 8 are formed using a vacuum evaporation method. The DLC film 6 is formed using a sputtering method. The shape of the substrate 1 is a circular plate shape with a diameter of 90 mm and a thickness of 5 mm. The transmittance was evaluated using a Fourier transform infrared spectrophotometer.

FIG. 3 is a diagram showing an example of the wavelength dependence of the transmittance of the optical member in Embodiment 1. FIG. Figure 3 shows the wavelength dependence of the optical member 11 of Example 1. The vertical axis of the graph shown in Fig. 3 represents the transmittance, and the horizontal axis represents the wavelength of light. Based on the wavelength dependence shown in Figure 3, a transmittance of 97.6% was achieved at a wavelength of 9.3μm. Since the protective window of the laser processing machine preferably has a transmittance of 97% or more, the optical member 11 satisfies the optical characteristics necessary for the protective window of the laser processing machine.

Here, a comparative example of Example 1 will be described. The optical member of the comparative example is an optical member having a substrate made of ZnS and two Y ₂ O ₃ films. On the main surface of the ZnS substrate, a first Y ₂ O ₃ film, a YF ₃ film, a second Y ₂ O ₃ film, a Ge film, and a DLC film are sequentially laminated from the main surface. The thickness of the first Y ₂ O ₃ film is set to 30 nm, the thickness of the YF ₃ film is set to 600 nm, the thickness of the second Y ₂ O ₃ film is set to 30 nm, the thickness of the Ge film is set to 30 nm, and the thickness of the DLC film is The thickness is set to 200 nm. The thickness of the substrate made of ZnS is 5 mm. The surface of the ZnS substrate on the opposite side to the main surface has a Y ₂ O ₃ film, a YF ₃ film, and a MgF ₂ film laminated in this order. The thickness of the Y ₂ O ₃ film was 80 nm, the thickness of the YF ₃ film was 1300 nm, and _{the thickness of the MgF 2} film was 400 nm. In addition, the illustration of the configuration of the optical member of the comparative example is omitted.

Fig. 4 is a graph showing the wavelength dependence of the transmittance of the optical member of the comparative example of Embodiment 1. The vertical axis of the graph shown in Fig. 4 represents transmittance, and the horizontal axis represents the wavelength of light. The wavelength dependence shown in Fig. 4 is the result of optical analysis of the optical component by using thin film calculation software. According to the wavelength dependence shown in Figure 3, the transmittance at a wavelength of 9.3μm is less than 95%. The optical member of the comparative example does not satisfy the optical characteristics necessary for the protective window of the laser processing machine.

Compared with the optical member of the comparative example, the optical member 11 of Example 1 can transmit infrared light with a high transmittance, and therefore can reduce the local temperature rise caused by light absorption. The optical member 11 of Embodiment 1 can make the thermal lens effect difficult to occur. The laser processing machine system can perform high-precision processing by using the optical member 11 of Example 1 in the protective window.

According to Embodiment 1, the optical components 10 and 11 have a multilayer film 7, and the multilayer film 7 is composed of three layers laminated in the order of the ZnS film 4, the Ge film 5, and the DLC film 6 from the side of the substrate 1. _{Thereby, compared with the case where two Y 2} O ₃ films are laminated on the first surface 2, the transmittance of infrared light can be improved. Thereby, the optical members 10 and 11 can exhibit the effect of not using oxides and being able to transmit infrared light with high transmittance.

Implementation status 2.

Fig. 5 is a cross-sectional view showing the configuration of the optical member in Embodiment 2 of the present invention. A multilayer film 9 is provided on the first surface 2 of the optical member 12 shown in Fig. 5. The multilayer film 9 has the following five films: two ZnS films, a first ZnS film 4a and a second ZnS film 4b , Two first Ge films 5a and second Ge films 5b belonging to Ge films, and one DLC film 6. In the second embodiment, the same reference numerals are assigned to the same components as those in the first embodiment, and the configuration that is different from the first embodiment will be mainly described.

The multilayer film 9 is composed of a first ZnS film 4a, a first Ge film 5a, a second ZnS film 4b, and a second Ge film belonging to the first zinc processed film from the first surface 2 side. 5b. The DLC film 6 is composed of five layers in sequence. An anti-reflection film 8 is provided on the second surface 3.

In the multilayer film 9, the thickness of the first ZnS film 4a is set to be in the range of 80nm to 700nm, the thickness of the first Ge film 5a is set to be in the range of 400nm to 1100nm, and the thickness of the second ZnS film 4b is set to In the range of 600 nm to 1000 nm, the thickness of the second Ge film 5b is set in the range of 10 nm to 70 nm, and the thickness of the DLC film 6 is set in the range of 50 nm to 300 nm. Thereby, the optical member 12 can utilize the effect caused by the interference of light to transmit infrared light with a high transmittance. The optical member 12 includes a substrate 1 made of Ge and a multilayer film 9 with the thickness of each layer set in the above-mentioned range, thereby achieving a transmittance of 98% or more for _{CO 2 laser light having a wavelength of 9 μm to 11 μm.} Thereby, the optical member 12 can satisfy the optical characteristics necessary for the protective window of the laser processing machine.

In addition, the optical member 12 is formed by laminating the combination of the second ZnS film 4b and the second Ge film 5b on the combination of the first ZnS film 4a and the first Ge film 5a, thereby improving the transmission of light having a specific wavelength. rate. In the laser processing machine, because the wavelength of the laser light used for processing is fixed, when the optical member 12 is applied to the protective window of the laser processing machine, high transmittance of the laser light system used for processing can be achieved . In addition, the multi-layer film 7 of Embodiment 1 or the multi-layer film 9 of Embodiment 2 can also be provided on the second surface 3 to replace the anti-reflective film 8.

Next, Embodiment 2 which is a specific example of Embodiment Mode 2 will be explained. The optical component 12 of Embodiment 2 has a multilayer film 9 provided on the first surface 2 and an anti-reflection film 8 provided on the second surface 3. In the multilayer film 9 of Example 2, the thickness of the first ZnS film 4a is set to 115nm, the thickness of the first Ge film 5a is set to 830nm, the thickness of the second ZnS film 4b is set to 875nm, and the thickness of the second Ge film The thickness of 5b is 30 nm, and the thickness of the DLC film 6 is 100 nm. The first ZnS film 4a, the second ZnS film 4b, the first Ge film 5a, the second Ge film 5b, and the anti-reflection film 8 are formed using a vacuum evaporation method. The DLC film 6 is formed using a sputtering method. The shape of the substrate 1 is a circular plate shape with a diameter of 90 mm and a thickness of 5 mm. The transmittance was evaluated using a Fourier transform infrared spectrophotometer.

FIG. 6 is a diagram showing an example of the wavelength dependence of transmittance in the optical member of Embodiment 2. FIG. Fig. 6 shows the wavelength dependence of the optical member 12 of Example 2. The vertical axis of the graph shown in Fig. 6 represents transmittance, and the horizontal axis represents the wavelength of light. Based on the wavelength dependence shown in Figure 6, a transmittance of 98% or more was achieved for a wavelength of 9.3μm. The optical member 12 satisfies the optical characteristics necessary for the protective window of the laser processing machine.

According to the second embodiment, the optical member 12 has a multilayer film 9 consisting of a first ZnS film 4a, a first Ge film 5a, a second ZnS film 4b, a second Ge film 5b, The DLC film 6 is composed of five layers laminated sequentially, thereby, compared with _{the case where two Y 2} O ₃ films are laminated on the first surface 2, the transmittance of infrared light can be improved. In addition, the optical member 12 can increase the transmittance of light having a specific wavelength. As a result, the optical member 12 can exhibit the effect of not using oxides and can transmit infrared light with high transmittance.

Implementation status 3.

In Embodiment 3, a laser processing machine with optical components is described. Fig. 7 is a diagram showing a schematic configuration of a laser processing machine in Embodiment 3 of the present invention. The laser processing machine 20 irradiates the workpiece 25 with laser light 22 to process the workpiece 25.

The laser processing machine 20 shown in FIG. 7 has a laser oscillator 21 that is a laser light source that generates laser light 22, a lens system that transmits laser light 22, and a protective window 24 that transmits laser light 22. The lens system includes a condensing lens 23 that condenses the laser light 22. In Figure 7, the illustration of lenses other than the condenser lens 23 in the lens system is omitted.

The protective window 24 is the optical member 10 and 11 in the first embodiment or the optical member 12 in the second embodiment. The laser oscillator 21 is a CO ₂ laser. The laser processing machine 20 performs laser processing of so-called drilling processing or cutting processing. Since the CO ₂ laser has the characteristics of high output oscillation and high absorption rate of the resin, the laser processing machine 20 is suitable for the hole processing of the printed circuit board.

The protective window 24 is provided at the emission end of the laser processing machine 20 that emits the laser light 22 to the outside. The protective window 24 is located between the condenser lens 23 and the workpiece 25. The protective window 24 has a position close to the workpiece 25 to a distance of about 100 mm. Therefore, the protective window 24 is exposed to an environment where dust or spatters generated during processing are scattered. In the laser processing machine 20, the first surface 2 side of the substrate 1 of the protective window 24 is arranged to face the workpiece 25, and the outer surface of the protective window 24 facing the workpiece 25 is provided with DLC膜6。 Film 6. The protective window 24 is provided with the DLC film 6 on the outer surface facing the workpiece 25 side, and can exhibit high environmental resistance that can withstand the environment during laser processing.

The protective window 24 is arranged at a position closest to the workpiece 25 among all the optical members constituting the laser processing machine 20. That is, there is no optical member between the workpiece 25 and the protective window 24. Therefore, when the protective window 24 generates a refractive index distribution due to the thermal lens effect, it is difficult to correct the refractive index distribution by introducing a new optical component or a mechanism for feeding back the laser light output. The protective window 24 uses the optical members 10, 11, and 12 of the embodiment 1 or the embodiment 2, thereby eliminating the need to add an element for correcting the refractive index distribution, and the optical characteristics necessary for the protective window 24 can be realized.

The laser processing machine 20 uses the optical components 10, 11, and 12 of the embodiment 1 or the embodiment 2 in the protective window 24, so that even if the processing speed is not limited to improve the processing accuracy, the processing can be performed with high precision. . Thereby, the laser processing machine 20 can realize high-productivity and high-precision processing without restricting the processing speed.

According to the third embodiment, the laser processing machine 20 is provided with the optical components 10, 11, and 12 of the first embodiment or the second embodiment, so that high environmental resistance and high optical characteristics can be obtained. In this way, the laser processing machine 20 can maintain a suitable life span on the protective window 24 while realizing high-precision laser processing.

Implementation status 4.

Embodiment 4 describes a laser processing machine provided with a covering member. Fig. 8 is a diagram showing a schematic configuration of a laser processing machine according to Embodiment 4 of the present invention. The laser processing machine 30 irradiates the workpiece 25 with laser light 22 to process the workpiece 25. In the fourth embodiment, the same reference numerals are given to the same components as those in the above-mentioned embodiment 3, and the configuration that is different from the third embodiment will be mainly described.

The laser processing machine 30 has a lens barrel 31 which is a covering member. The lens barrel 31 covers the outer periphery of the condenser lens 23 and the outer periphery of the protective window 24. The protection window 24 is provided at the end of the side where the laser light 22 in the lens barrel 31 is emitted. The condenser lens 23 is arranged inside the lens barrel 31. The laser processing machine 30 is provided with a lens barrel 31 to prevent dust or spatters generated when the workpiece 25 is processed from adhering to the condenser lens 23. The covering member may be a member capable of preventing the adhesion of dust or spatter to the condenser lens 23 and is not limited to the lens barrel 31. Regarding the material and shape of the covering member, any shape that can prevent the adhesion of dust or spatter to the condenser lens 23 is sufficient.

According to the embodiment 4, the laser processing machine 30 is provided with the optical components 10, 11, 12 and the lens barrel 31 of the embodiment 1 or the embodiment 2, so that further high environmental resistance can be obtained, and at the same time, the High optical properties.

The structure shown in the above embodiment is an example of the content of the present invention, and can be combined with other known technologies, and part of the structure can be omitted or changed without departing from the scope of the present invention.

1: substrate

2: first side

3: second side

4: ZnS film

5: Ge film

6: DLC film

7: Multilayer film

10: Optical components

Claims (11)

An optical member comprising: a substrate composed of germanium, and a multilayer film composed of at least three layers laminated in the order of a second zinc compound film, a second germanium film, and a diamond-like carbon film from the substrate side, the aforementioned The thickness of the second zinc compound film is in the range of 600 nm to 1000 nm, the thickness of the foregoing second germanium film is in the range of 10 nm to 70 nm, and the thickness of the foregoing diamond-like carbon film is in the range of 50 nm to 300 nm. The optical member described in claim 1, wherein the substrate has a first surface and a second surface opposite to the first surface, and the multilayer film is provided on the first surface. The optical member described in claim 2 wherein the multilayer film is further provided on the second surface. The optical member described in the second item of the scope of patent application is provided with an anti-reflection film provided on the aforementioned second surface. The optical member according to any one of items 1 to 4 in the scope of the patent application, wherein the diamond-like carbon film is in contact with the second germanium film. The optical member according to any one of claims 2 to 4, wherein the multilayer film is composed of a first zinc compound film, a first germanium film, a second zinc compound film, and a second zinc compound film from the side of the substrate. A multilayer film consisting of at least five layers of a germanium film and a diamond-like carbon film stacked in sequence. The optical member described in claim 1, wherein the multilayer film system includes only one layer each of the second zinc compound film and the second germanium film. According to the optical member described in claim 6, wherein the thickness of the first zinc compound film is in the range of 80 nm to 700 nm, and the thickness of the first germanium film is in the range of 400 nm to 1100 nm. A laser processing machine is provided with: a laser light source for generating laser light, and an optical member described in any one of the patent applications 1 to 8 for transmitting the laser light. The laser processing machine according to claim 9, wherein the optical member is provided at the exit end that emits the laser light to the outside of the laser processing machine. The laser processing machine described in claim 9 or 10 includes a covering member covering the outer periphery of a condenser lens that condenses the laser light and the outer periphery of the optical member.

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