Laser device, laser processing device, and method for manufacturing electronic components

Abstract

The laser device (100) comprises a housing (1) that encloses the laser gas, which is the laser medium; a resonator (2) that includes multiple reflectors and amplifies and outputs the laser light; a partition wall that separates the internal space of the housing (1) from the external space of the housing (1) and a transmission window (6) through which the laser light output from the resonator (2) passes; and electrodes (11, 12) that are spaced apart in pairs in a direction perpendicular to the optical axis (L) of the laser light. The resonator (2) includes a partial reflector (3) that includes at least a diamond material and outputs the amplified laser light to the outside, and a total reflector (4) that is spaced apart from the partial reflector (3) and reflects the laser light.

Description

[Technical Field]

[0001] This disclosure relates to a laser device, a laser processing device, and a method for manufacturing electronic components. [Background technology]

[0002] Conventionally, laser devices that emit laser light used for laser processing are known. For example, Patent Document 1 discloses a power laser comprising an annular support, a partially transparent first window provided at one end of the annular support, and a reflective second window provided at the other end of the annular support. The interior of the annular support, surrounded by the first and second windows, is an optical cavity filled with laser gas. The first and second windows are made of diamond flakes with flat, parallel surfaces. This power laser particularly utilizes a CO2 laser. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-5951 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, the technology described in Patent Document 1 separates the optical cavity containing the laser gas from the outside of the annular support by a first window and a second window made of diamond flakes. Therefore, the difference in air pressure between the optical cavity and the outside of the annular support can cause stress on the diamond flakes, potentially leading to distortion. Generally, the laser gas pressure of a CO2 laser is several tens to several hundreds of Torr. If the diamond flakes are thin, they can be distorted by the pressure and may even break. Distortion of the diamond flakes adversely affects the beam characteristics of the laser light output from the laser device.

[0005] This disclosure has been made in view of the above, and aims to provide a laser device that can reduce adverse effects on the beam characteristics of laser light. [Means for solving the problem]

[0006] To solve the above-mentioned problems and achieve the objective, the laser apparatus according to this disclosure comprises a housing that encapsulates a laser gas, which is a laser medium; a resonator that includes a plurality of reflectors and amplifies and outputs laser light; a partition wall that separates the internal space of the housing from the external space of the housing and through which the laser light output from the resonator passes; and electrodes that are arranged in pairs at intervals in a direction perpendicular to the optical axis of the laser light. The resonator includes a partial reflector that includes at least a diamond material and outputs the amplified laser light to the outside, and a total reflector that is spaced apart from the partial reflector and reflects the laser light. A partial reflector consists of a one-dimensional retroreflector formed by orthogonally aligning the reflective surface of a diamond component with the reflective surface of a metal mirror. Of the multiple reflectors, at least one of the reflectors other than the partial reflector has a curved reflective surface.

[0007] The laser processing apparatus relating to this disclosure is the above The system comprises a laser device and a laser processing machine that focuses the laser light emitted from the laser device and irradiates it onto a workpiece. ru.

[0008] The method for manufacturing electronic components relating to this disclosure is: the above A method for manufacturing electronic components by focusing laser light emitted from a laser device with a laser processing machine and irradiating it onto a workpiece, wherein the laser light is amplified in a resonator, and after the laser light is output from a partial reflector which includes a diamond material in at least part of a plurality of reflectors, the laser light is passed through a transparent window which serves as a partition separating the internal space of the housing from the external space of the housing, and the laser light is emitted from the laser device. [Effects of the Invention]

[0009] The laser device described herein has the effect of reducing adverse effects on the beam characteristics of laser light. [Brief explanation of the drawing]

[0010] [Figure 1] A schematic diagram showing a laser processing apparatus equipped with a laser device according to Embodiment 1. [Figure 2] A schematic perspective view showing an example of the overall configuration of the laser device according to Embodiment 1. [Figure 3] A schematic plan view showing an example of the overall configuration of the laser device according to Embodiment 1, viewed from the +Y direction. [Figure 4] A cross-sectional view showing a laser device according to Embodiment 1, in which a partial reflector and a transmission window are held in the housing using a holder member. [Figure 5] An explanatory diagram showing how laser light passes through a partial reflector made of diamond material and a transmission window made of ZnSe. [Figure 6] This is an explanatory diagram illustrating a comparative example with Figure 5, showing how laser light passes through a partial reflector made of ZnSe. [Figure 7] This graph compares the thermal lens index with respect to the reflectance of the partial reflective film when using a partial reflector made of diamond material and a transmissive window made of ZnSe, and when using a partial reflector made of ZnSe alone. [Figure 8] This graph compares the thermal lens index with respect to the reflectance of the partial reflective film when using a partial reflector made of diamond material and a transmissive window made of ZnSe, and when using a partial reflector made of ZnSe alone. [Figure 9] This graph compares the thermal lens index with respect to the reflectance of the partial reflective film when using a partial reflector made of diamond material and a transmissive window made of ZnSe, and when using a partial reflector made of ZnSe alone. [Figure 10] A modified example of the laser device according to Embodiment 1, showing a cross-sectional view in which a partial reflector and a transmission window are held in the housing using a holder member. [Figure 11] An explanatory diagram showing two different diamond components in which the radius of curvature is generated by pressure strain. [Figure 12]A perspective view schematically illustrating an example of the overall configuration of a laser device according to Embodiment 2 [Figure 13] A plan view schematically illustrating an example of the overall configuration of the laser device according to Embodiment 2 as viewed from the +Y direction [Figure 14] An explanatory view schematically illustrating a partial reflection mirror of the laser device according to Embodiment 2 [Figure 15] An explanatory view schematically illustrating a modified example of the partial reflection mirror of the laser device according to Embodiment 2 [Figure 16] A cross-sectional view illustrating the laser device according to Embodiment 2, showing a state where the partial reflection mirror and a transmission window are held in a housing using a holder member [Figure 17] An explanatory view illustrating the partial reflection mirror of the laser device according to Embodiment 2, showing a case where an incident angle θ1 of laser light incident on a diamond member is set to 45° [Figure 18] An explanatory view illustrating the partial reflection mirror of the laser device according to Embodiment 2, showing a case where an incident angle θ2 of laser light incident on a diamond member is set smaller than 45° [Figure 19] A perspective view schematically illustrating an example of the overall configuration of a laser device according to Embodiment 3 [Figure 20] A plan view schematically illustrating an example of the overall configuration of the laser device according to Embodiment 3 as viewed from the +Y direction [Figure 21] A plan view schematically illustrating an example of the overall configuration of a laser device according to Embodiment 4 as viewed from the +Y direction [Figure 22] A perspective view schematically illustrating an example of the overall configuration of a laser device according to Embodiment 5 [Figure 23] An explanatory view schematically illustrating a partial reflection mirror of the laser device according to Embodiment 5 [Figure 24] A cross-sectional view illustrating the laser device according to Embodiment 5, showing a state where the partial reflection mirror is held in a housing using a holder member DETAILED DESCRIPTION OF THE INVENTION

[0011] The laser apparatus, laser processing apparatus, and method for manufacturing electronic components according to embodiments of this disclosure will be described in detail below with reference to the drawings.

[0012] Embodiment 1. Figure 1 is a schematic diagram showing a laser processing apparatus equipped with a laser device according to Embodiment 1. When describing directions hereafter, we will follow the right-handed XYZ coordinate system shown in Figure 1. The X-axis, Y-axis, and Z-axis directions are mutually orthogonal. The laser processing apparatus 300 shown in Figure 1 is a device that processes a workpiece 400 by irradiating it with laser light Lb to manufacture, for example, electronic components. Processing includes, for example, cutting, welding, and drilling. The workpiece 400 is, for example, a metal plate or a substrate. The laser processing apparatus 300 comprises a laser device 100 that emits laser light Lb, and a laser processing machine 200 that focuses the laser light Lb emitted from the laser device 100 and irradiates it onto the workpiece 400. The laser processing machine 200 comprises optical components such as mirrors and lenses (not shown) for guiding the laser light Lb to the workpiece 400, and a housing 200a for housing the optical components. Although not shown in the diagram, the laser processing apparatus 300 is equipped with a drive mechanism for moving the position of the workpiece 400 in the X-axis, Y-axis, and Z-axis directions.

[0013] Figure 2 is a schematic perspective view showing an example of the overall configuration of a laser device according to Embodiment 1. Figure 3 is a schematic plan view showing an example of the overall configuration of a laser device according to Embodiment 1 from the +Y direction. Note that in Figure 2, apertures 15 and 16 shown in Figure 3 are omitted for illustrative purposes. The laser device 100 shown in Figures 2 and 3 exemplifies a case where a discharge occurs in the Y-axis direction, which is perpendicular to the Z-axis, which is the optical axis L of the laser beam, and a gas flow occurs in the X-axis direction, which is perpendicular to the Z-axis and Y-axis, in the discharge region S. The laser device 100 shown in Figure 2 is called a three-axis orthogonal gas laser, in which the optical axis L of the laser beam, the direction of the discharge, and the direction of the gas flow are all orthogonal to each other. As shown in Figures 2 and 3, the laser device 100 includes a housing 1, a resonator 2, electrodes 11 and 12, a heat exchanger 13, a blower 14, apertures 15 and 16, and a transmission window 6.

[0014] As shown in Figure 2, the housing 1 is a box-shaped component that encloses the laser gas, which is the laser medium. Inside the housing 1 are a resonator 2, electrodes 11 and 12, a heat exchanger 13, a blower 14, and apertures 15 and 16. As shown in Figure 3, the housing 1 has an opening 10a formed in the side wall 10 in the direction of the optical axis L. The inside and outside of the housing 1 are in communication through the opening 10a. The opening 10a is the part that allows the laser light inside the housing 1 to be emitted to the outside of the housing 1. The housing 1 is provided with a transparent window 6 so as to close the opening 10a.

[0015] As shown in Figures 2 and 3, the resonator 2 includes multiple mirrors and amplifies and outputs laser light. The resonator 2 comprises a partial mirror 3, a total mirror 4, and a folded mirror 5 as multiple mirrors. The optical axis L of the resonator 2 is positioned so that the laser light propagates between electrodes 11 and 12 roughly in the Z-axis direction. The partial mirror 3 and the total mirror 4 are spaced apart. The partial mirror 3 constitutes one end of the resonator 2. Laser light is output from the partial mirror 3 of the resonator 2. The total mirror 4 constitutes the other end of the resonator 2. The folded mirror 5 is positioned on the optical axis L of the resonator 2 between the partial mirror 3 and the total mirror 4. The partial mirror 3 and the folded mirror 5 are spaced apart from each other in the Z-axis direction. The total mirror 4 and the folded mirror 5 are spaced apart from each other in the X-axis direction. The partial reflecting mirror 3 and the total reflecting mirror 4 are positioned with a gap between them in the X-axis and Z-axis directions.

[0016] The partial reflector 3 outputs the laser light amplified by the resonator 2 to the outside. The material of the partial reflector 3 is, for example, diamond. The partial reflector 3 is positioned away from one end of the electrodes 11 and 12 in the Z-axis direction. The inner surface 3a of the partial reflector 3 is coated with, for example, a coating that gives a desired reflectivity for the wavelength of the laser light. The outer surface 3b of the partial reflector 3 is coated with, for example, a coating that gives a high transmittance for the wavelength of the laser light. The partial reflector 3 may also have a wedge configuration on both its inner and outer surfaces. Furthermore, the partial reflector 3 may have a curvature on either its inner or outer surface.

[0017] The total reflection mirror 4 is a one-dimensional retroreflector. The reflective surface of the total reflection mirror 4 is coated, for example, to give high reflectivity to the wavelength of laser light. The total reflection mirror 4 causes light to be totally reflected towards the partial reflection mirror 3 at its reflective surface.

[0018] The folding mirror 5 is a metal mirror used to bend the optical axis L at a 90° angle. The folding mirror 5 is positioned on the optical axis L between the partial mirror 3 and the total reflecting mirror 4. The folding mirror 5 has a curved reflective surface and causes light to be totally reflected toward the partial mirror 3 and the total reflecting mirror 4. The number of folding mirrors 5 may be one or two or more, as shown in Figures 2 and 3.

[0019] As shown in Figure 2, the two electrodes 11 and 12 are spaced apart in the Y-axis direction. A laser gas, which functions as a laser medium, is supplied between the two electrodes 11 and 12. In the laser device 100, a silent discharge is generated and the laser gas is excited by applying a high-frequency voltage in the Y-axis direction between the two electrodes 11 and 12. For example, when generating a laser pulse, intermittent operation may be used, where the high-frequency voltage is applied only while the laser pulse is being generated. The space between the two electrodes 11 and 12 becomes a discharge region S where the laser gas is excited by the discharge. The laser gas is a mixed gas having some or all of the following: CO2, N2, He, CO, Xe, O2, H2, etc. With the laser gas, for example, a CO2 laser with a wavelength of 10.6 μm or 9.3 μm, or a CO laser with a wavelength in the 5 μm to 6 μm band, etc., is emitted.

[0020] In the resonator 2, the laser beam travels back and forth between the inner surface 3a of the partial reflector 3 and the reflective surface of the total reflector 4, and the laser gas excited in the discharge region S between the two electrodes 11 and 12 causes the laser beam to oscillate. In other words, the laser beam is amplified. A portion of the amplified laser beam is output from the outer surface 3b of the partial reflector 3 and is output to the outside of the housing 1 through the transmission window 6.

[0021] As the laser gas passes between the two electrodes 11 and 12, the gas is heated by the discharge, creating a temperature distribution. Specifically, the gas temperature is lower on the upstream side (+X direction) and higher on the downstream side (-X direction). This temperature distribution generates a refractive index distribution. This refractive index distribution causes the light passing through to bend, a phenomenon known as a gas prism. When a gas prism occurs, the position of the optical axis L becomes unstable, which can have adverse effects such as disrupting the laser beam profile or, in some cases, stopping the oscillation. The total reflection mirror 4, which consists of one-dimensional retroreflectors, has the effect of suppressing these adverse effects. The position of the optical axis L on the retroreflector is fixed at the valley of the retroreflector, that is, at the position where the two mirrors are orthogonal. As a result, the position of the optical axis L of the resonator 2 is stabilized, and the profile of the output laser beam and the optical axis L when it propagates thereafter are also stabilized.

[0022] As shown in Figure 2, the heat exchanger 13 is provided to cool the laser gas excited in the discharge region S. Cooling the laser gas suppresses the temperature rise inside the housing 1. The blower 14 is positioned to circulate the laser gas within the discharge region S and generates a gas flow, which is the flow of laser gas, in a rotational direction around the Z axis. Specifically, the laser gas flows from the blower 14 toward the discharge region S in the direction indicated by arrow F1, and then flows through the discharge region S in the -X axis direction. After passing through the discharge region S, the laser gas flows toward the heat exchanger 13 in the direction indicated by arrow F2, and is then cooled in the heat exchanger 13. The laser gas cooled in the heat exchanger 13 flows back into the blower 14 and is circulated and supplied again to the discharge region S. Note that the direction of the gas flow in the discharge region S is not limited to the -X axis direction as shown in the figure, but may also be in the +X axis direction. Also, the number of blowers 14 is not limited to the one shown in the figure, but may be two or more.

[0023] As shown in Figure 3, apertures 15 and 16 each have an opening through which the optical axis L passes. Aperture 15 is positioned on the optical axis L between the partial reflector 3 and electrodes 11 and 12. Aperture 15 is positioned so that the optical axis L passes through the center of its opening. Aperture 16 is positioned on the optical axis L between the folded reflector 5 and electrodes 11 and 12. Aperture 16 is positioned so that the optical axis L passes through the center of its opening.

[0024] The material of the transmission window 6 is, for example, zinc selenide (ZnSe). As shown in Figure 3, the transmission window 6 is installed to close an opening 10a formed in the side wall 10 of the housing 1. The transmission window 6 acts as a partition separating the internal space of the housing 1 from the external space of the housing 1, and the laser light output from the resonator 2 passes through it. The inner surface of the transmission window 6 is the internal space of the housing 1, for example, in a laser gas atmosphere. The outer surface of the transmission window 6 is the external space of the housing 1, in the atmosphere. The transmission window 6 may be installed at an angle so that its inner and outer surfaces are not perpendicular to the optical axis L of the laser light. The transmission window 6 may also have a wedge on its inner and outer surfaces. Furthermore, the transmission window 6 may have a curvature on its inner or outer surface. In addition, it is desirable that the distance between the partial reflector 3 and the transmission window 6 in the direction of the optical axis L be small. Moreover, the partial reflector 3 and the transmission window 6 may be in contact.

[0025] Figure 4 is a cross-sectional view of a laser device according to Embodiment 1, showing a state in which a partial reflector and a transmission window are held in the housing using a holder member. In Figure 4, the area A on the left, separated by the side wall 10 of the housing 1, is the interior of the housing 1 and is the laser gas atmosphere side where the laser gas is sealed. In Figure 4, the area B on the right is the exterior of the housing 1 and is the atmospheric side.

[0026] As shown in Figure 4, the partial reflector 3 and the transmission window 6 are fixed by a cylindrical holder member 7, which is composed of three cylindrical members 70, 71, and 72, as an example, and can be treated as a single integrated part with the holder member 7. The three cylindrical members 70, 71, and 72 are arranged in a line so that their internal tubes are in communication with each other, and are fastened together with screws 73. The cylindrical members 70 and 72 each constitute an end. The cylindrical member 71 is positioned between the cylindrical members 70 and 72 and constitutes an intermediate section. A linear optical axis L is positioned inside the tube of the holder member 7. Of the three cylindrical members 70, 71, and 72, the internal tube of cylindrical member 72 is in communication with the inside of the housing 1. Of the three cylindrical members 70, 71, and 72, the internal tube of cylindrical member 70 is in communication with the outside of the housing 1. The three cylindrical members 70, 71, and 72 are each provided with an O-ring 74a between adjacent members. The partial reflector 3 is positioned inside the cylinder of the holder member 7, and its outer edge is fitted into a groove formed on the inner wall surface of the cylindrical member 71 for fixation. An O-ring 74b is provided between the partial reflector 3 and the cylindrical member 71. Similarly, the transmissive window 6 is positioned inside the cylinder of the holder member 7, and its outer edge is fitted into grooves formed on the inner wall surfaces of the cylindrical members 70 and 71 for fixation. An O-ring 74c is provided between the transmissive window 6 and the cylindrical member 70.

[0027] The holder member 7 is fixed to the side wall 10 of the housing 1 via a cylindrical adjustment member 8. The inside of the holder member 7's cylinder communicates with the inside of the housing 1. The adjustment member 8 has an adjustment board 8a that holds the holder member 7 and a fixing part 8b that is fitted into and fixed to an opening 10a formed in the side wall 10 of the housing 1. The inside of the adjustment member 8's cylinder communicates with the inside of the holder member 7, and the optical axis L is positioned there. The adjustment board 8a holds the holder member 7 by fixing the cylindrical member 72. An O-ring 81 is provided between the adjustment board 8a and the cylindrical member 72. An O-ring 80 is provided between the outer circumferential surface of the fixing part 8b and the inner circumferential surface of the opening 10a in the side wall 10. The adjustment board 8a is also provided with an angle adjustment mechanism 82, such as a micrometer. The holder member 7's angle can be adjusted by the adjustment member 8. This allows for alignment of the partial reflector 3.

[0028] Furthermore, as shown in Figure 4, the inside of the holder member 7 has a first internal space I1 that communicates with the inside of the housing 1, and a second internal space I2 that is separated from the first internal space I1 by the partial reflector 3 and surrounded by the partial reflector 3 and the transparent window 6. The holder member 7 has a through hole 7a that connects the first internal space I1 and the second internal space I2. The through hole 7a functions as a vent that connects the first internal space I1 and the second internal space I2. As a result, the first internal space I1 and the second internal space I2 have the same gas pressure, and the pressure difference between the inside of the housing 1 and the outside air is applied to the transparent window 6. Note that the holder member 7 is not limited to a configuration in which the through hole 7a is formed in one place, but may also have a configuration in which the through hole 7a is formed in two or more places, and gas may flow into the second internal space I2 surrounded by the partial reflector 3 and the transparent window 6. For example, each through hole 7a may be formed in a part of the housing 1 where the pressure is different. In other words, gas flow may be generated by forming one through-hole 7a at a positive pressure position and connecting the other through-hole 7a to a negative pressure position.

[0029] The material of the partial reflector 3 is, for example, diamond. The material of the transmission window 6 is, for example, ZnSe. If the reflectivity of the partial reflector 3 is, for example, 70%, then about 30% of the laser beam from the resonator 2 will be irradiated onto the transmission window 6. For example, in the case of a laser device 100 with an output of 1 kW, the laser beam irradiated onto the transmission window 6 is 1 kW, but the laser beam irradiated onto the partial reflector 3 will be 3.33 kW.

[0030] For example, if a partial reflector is made of ZnSe, a 3.33kW laser beam is irradiated onto the ZnSe. At this time, the ZnSe absorbs a portion of the laser beam, creating a thermal lens. When a thermal lens occurs, the divergence angle of the laser beam after it is emitted from the laser device fluctuates. In other words, if a laser device with a partial reflector made of ZnSe is applied to a laser processing device, the intensity of the laser beam irradiated onto the workpiece may be unstable, potentially causing processing defects. On the other hand, if the partial reflector is made of diamond, its thermal conductivity is two orders of magnitude greater than that of a ZnSe partial reflector, so the effect of the thermal lens caused by the partial reflector is significantly reduced. Furthermore, the laser beam irradiated onto a ZnSe transmission window is less than one-third of that of a diamond partial reflector. Therefore, when the partial reflector is made of diamond, the effect of the thermal lens can be reduced to about one-third compared to when the partial reflector is made of ZnSe.

[0031] Furthermore, in the first embodiment, the laser device 100 has a first internal space I1 that communicates with the inside of the housing 1, and a second internal space I2 that is separated from the first internal space I1 by a partial reflector 3 and surrounded by the partial reflector 3 and a transmissive window 6, and these two spaces are subjected to the same gas pressure through a through hole 7a. As a result, pressure strain does not occur in the partial reflector 3, there is no risk of the partial reflector 3 being destroyed by pressure differences, and there is no change in curvature, so variations in the beam diameter and divergence angle of the laser light can be suppressed. In addition, the thickness of the diamond material constituting the partial reflector 3 can be reduced, thus reducing manufacturing costs.

[0032] Next, the effects of the laser device 100 according to Embodiment 1 will be described in more detail with reference to Figure 5. Figure 5 is an explanatory diagram showing how laser light passes through a partial reflector made of diamond material and a transmission window made of ZnSe. d d is the thickness of the partial reflecting mirror 3. z is the thickness of the transmission window 6. C1 and C2 are coatings applied to the surface of the partial reflector 3. C3 and C4 are coatings applied to the surface of the transmission window 6. C1 is a partial reflective film. C2, C3 and C4 are anti-reflective coatings. As shown in Figure 5, the laser beam is incident on the partial reflector 3 with power A. Then, part of the laser beam is reflected by the partial reflective film C1, and the remaining light passes through the inside of the partial reflector 3 with power A' and is irradiated onto the anti-reflective coating C2 on the output side. If the reflectance of the partial reflective film C1 is R, then A' = A × (1 - R). The laser beam that has passed through the partial reflector 3 is irradiated onto the anti-reflective coating C3 of the transmission window 6 with power A', passes through the inside of the transmission window 6 with power A', is irradiated onto the anti-reflective coating C4 on the output side of the transmission window 6 with power A', and is output to the outside with power A'.

[0033] Here, the absorption coefficients of the coated surfaces of C1, C2, C3, and C4 are α1, α2, α3, and α4, respectively. The absorption coefficient of the diamond component is α d (1 / mm), the absorption coefficient of ZnSe is α z Let (1 / mm). In this case, the laser light absorbed by the entire diamond component is given by the following equation (1).

[0034]

number

[0035] On the other hand, the laser light absorbed by the entire ZnSe is given by equation (2) below.

[0036]

number

[0037] Here, the size of the thermal lens is determined by the refractive index temperature dependence dn / dT, which is a physical property of the material, the thermal conductivity λ, and the power P absorbed by the material. This is defined as the thermal lens index T i , resulting in the following formula (3). A larger value of this parameter means a larger thermal lens.

[0038]

Math.

[0039] Here, the thermal lens index formed by the partial reflecting mirror 3 formed of the diamond member described above and the transmission window 6 formed of ZnSe is represented by the following formula (4).

[0040]

Math.

[0041] Here, (dn / dT) d is the refractive index temperature dependence of diamond. λ d is the thermal conductivity of diamond. Further, (dn / dT) z is the refractive index temperature dependence of ZnSe. λ z is the thermal conductivity of ZnSe.

[0042] FIG. 6 is a comparative example for FIG. 5, and is an explanatory view showing a state in which laser light passes through a partial reflecting mirror formed of ZnSe. d z is the thickness of the partial reflecting mirror 3'. C1' and C2' are coatings applied to the surface of the partial reflecting mirror 3'. C1' is a partial reflection film. C2' is an anti-reflection coating. As shown in FIG. 6, the laser light is incident on the partial reflecting mirror 3' with power A. Thereafter, a part of the laser light is reflected by the partial reflection film C1', the remaining light passes through the interior of the partial reflecting mirror 3' with power A', irradiates the anti-reflection coating C2' on the output side with power A', and is output to the outside with power A'. In the partial reflecting mirror 3' formed of ZnSe shown in FIG. 6, the laser light absorbed by the entire ZnSe is represented by the following formula (5).

[0043]

number

[0044] In this case, the thermal lensing index due to the partial reflecting mirror 3' made of ZnSe is given by the following equation (6).

[0045]

number

[0046] Therefore, the laser device 100 according to Embodiment 1 is effective when the following equation (7) is satisfied.

[0047]

number

[0048] Here, we will give a more specific example of the above conditions. It is known that the absorptivity of diamond is approximately 0.135 to 0.092 (1 / cm) in the wavelength range of a CO2 laser from 9.2 μm to 10.6 μm. Also, a typical value for dn / dT of diamond (at a temperature of 300 K) is 3 × 10⁻¹⁰. -5 Furthermore, the thermal conductivity λ of diamond is approximately 1800 (W / mK). On the other hand, the absorptivity of ZnSe is approximately 0.0005 (1 / cm). The dn / dT of ZnSe is 6.1 × 10⁻⁶. -5 The thermal conductivity λ of ZnSe is 18 (W / mK). The absorption rate of the coating is similar for diamond and ZnSe, at approximately 0.1% per surface. However, if the surface of the coating deteriorates, the absorption rate of the coating may increase to approximately 0.3%.

[0049] Figure 7 is a graph comparing the thermal lensing index against the reflectance of the partial reflective film when using a partial reflector made of diamond material and a transmissive window made of ZnSe, and when using a partial reflector made of ZnSe. The horizontal axis represents the reflectance of the partial reflective film. The vertical axis represents the thermal lensing index. In Figure 7, the thermal lensing index is shown when the absorptive rate of diamond is 0.135 and the absorptive rate per surface of the coating is 0.1%. The thicknesses of the diamond material are 1.5 mm, 1.0 mm, and 0.5 mm. The thickness of each ZnSe is 6 mm. As shown in Figure 7, when the thickness of the diamond material is 1.5 mm, the condition for satisfying equation (7) above is when the reflectance of the partial reflective film is 10% or more. When the thickness of the diamond material is 1.0 mm, the condition for satisfying equation (7) is when the reflectance of the partial reflective film is 7.1% or more. When the thickness of the diamond component is 0.5 mm, the condition for satisfying equation (7) is that the reflectance of the partial reflective film is 4.1% or more.

[0050] While thinner diamond components are more cost-effective, excessively thin diamond components become brittle. Therefore, from a strength standpoint, it is desirable for the diamond component to be at least 0.5 mm thick. On the other hand, from a manufacturing cost standpoint, it is desirable for the diamond to be 1.5 mm or less thick. Thus, in this case, by setting the reflectivity of the partial reflective film to 10% or more, the configuration using a partial reflector 3 made of diamond and a transmissive window 6 made of ZnSe results in a smaller thermal lens than the configuration using a partial reflector made of ZnSe. Here, A=1. Furthermore, the effect of the thickness of the transmissive window 6 can be ignored.

[0051] Figure 8 is a graph comparing the thermal lens index with respect to the reflectance of the partial reflective film when using a partial reflector made of diamond material and a transmissive window made of ZnSe, and when using a partial reflector made of ZnSe. The horizontal axis represents the reflectance of the partial reflective film. The vertical axis represents the thermal lens index. In Figure 8, the thermal lens index is shown when the partial reflective film is attached to the outside of the partial reflector 3 made of diamond material, i.e., the surface facing the transmissive window 6. The thickness of the diamond material is 1.5 mm. The thickness of each ZnSe is 6 mm. As shown in Figure 8, the condition that satisfies the above equation (7) is when the reflectance of the partial reflective film is 11% or more. In this case, the effect can be obtained even if the partial reflector 3 is used upside down, so the partial reflective film can be attached to the surface of the partial reflector 3 without worrying about the front or back of the partial reflector 3, making handling easier.

[0052] Generally, a partial reflector 3 has a partial reflective coating on the inner surface of the resonator 2. The type of coating is difficult to determine by visual inspection. In particular, if the partial reflector 3 is made of a flat surface, there is a risk of mistakenly attaching the partial reflective coating to the outer surface instead of the inner surface of the partial reflector 3. The laser device 100 according to Embodiment 1 is effective even in such cases. That is, in the laser device 100 according to Embodiment 1, even if the partial reflective coating is mistakenly attached to the outer surface instead of the inner surface of the partial reflector 3, thermal lensing is hardly generated, so it is possible to obtain laser light similar to that obtained when the partial reflective coating is attached to the inner surface. Incidentally, in the case of a partial reflector made of ZnSe, if the partial reflective coating is mistakenly attached to the outer surface instead of the inner surface of the partial reflector, the laser light in the resonator will pass through the inside of the partial reflector, so the effect of thermal lensing is large and the beam diameter in the resonator changes significantly. For this reason, when the partial reflective coating is attached to the outer surface of a partial reflector made of ZnSe, it is not possible to obtain laser light similar to that obtained when the partial reflective coating is attached to the inner surface of the partial reflector.

[0053] Figure 9 is a graph comparing the thermal lensing index against the reflectance of the partial reflective film when using a partial reflector made of diamond material and a transmissive window made of ZnSe, and when using a partial reflector made of ZnSe. The horizontal axis represents the reflectance of the partial reflective film. The vertical axis represents the thermal lensing index. In Figure 9, the thermal lensing index is shown when the coating of the partial reflective film deteriorates and the absorptive rate increases to 0.3%. The thicknesses of the diamond material are 1.5 mm, 1.0 mm, and 0.5 mm. The thickness of each ZnSe is 6 mm. When the thickness of the diamond material is 1.5 mm, the condition for satisfying equation (7) above is when the reflectance of the partial reflective film is 4.2% or more. When the thickness of the diamond material is 1.0 mm, the condition for satisfying equation (7) is when the reflectance of the partial reflective film is 3.1% or more. When the thickness of the diamond material is 0.5 mm, the condition for satisfying equation (7) is when the reflectance of the partial reflective film is 2.0% or more.

[0054] From the above, when the partial reflector 3 and the transmission window 6 are combined, the effect of reducing thermal lensing can be obtained by making the reflectivity of the partial reflector 3, which is made of diamond material, 11% or more. In other words, the partial reflector 3, which is made of diamond material, should be coated with a partial reflective film that has a reflectivity of 11% or more.

[0055] Figure 10 is a modified example of the laser apparatus according to Embodiment 1, and is a cross-sectional view showing a state in which a partial reflector and a transmission window are held in the housing using a holder member. In the laser apparatus 100 according to Embodiment 1, when the pressure of the laser gas inside the housing 1 is low, the second internal space I2 surrounded by the partial reflector 3 and the transmission window 6 may be configured to become a vacuum. As shown in Figure 10, the holder member 7 is provided with a valve 75 that can open and close the through hole 7a from the outside. When creating a vacuum in the internal space of the housing 1, the valve 75 is opened, the valve 75 is closed after the vacuum is created, and then laser gas is introduced into the housing 1. When the pressure of the laser gas is close to a vacuum, the pressure difference on the partial reflector 3 is small. Therefore, the pressure strain on the partial reflector 3 is small, there is no risk of the partial reflector 3 being destroyed by the pressure difference, and the change in the curvature of the partial reflector 3 is also small. Furthermore, the second internal space I2 surrounded by the partial reflector 3 and the transmission window 6 may be filled with an inert gas such as nitrogen. As a result, the laser light is not absorbed between the partial reflector 3 and the transmission window 6, which suppresses beam diameter fluctuations known as gas lensing, and thus provides a more stable laser beam.

[0056] Furthermore, if a partially reflective coating is applied to the diamond component, there is a risk that the coating may peel off due to pressure distortion of the diamond component. Increasing the thickness of the diamond component to prevent distortion would increase its cost, making it difficult to use for industrial purposes. In addition, increasing the thickness of the diamond component increases manufacturing time, which may create issues with availability.

[0057] For example, as in the technology described in Patent Document 1 above, when sealing the laser gas inside the housing with a diamond component, if the diamond component is thin, the pressure difference will cause distortion in the diamond component. That is, the surface of the diamond component will be distorted convexly on the low-pressure side and concavely on the high-pressure side. When a coating such as a partially reflective or anti-reflective film is applied to the diamond component, tensile stress is generated in the coating on the convexly distorted surface and compressive stress is generated in the coating on the concavely distorted surface. This can cause cracks in the coating, and eventually the coating may peel off.

[0058] Figure 11 is an explanatory diagram showing two different diamond components that exhibited different radii of curvature due to pressure strain. One diamond component, D1, has a diameter Φ of 33 mm and a thickness t of 1.1 mm. The other diamond component, D2, has a diameter Φ of 60 mm and a thickness t of 1.2 mm. No coating peeling occurred in diamond component D1, which developed a radius of curvature of R34 m due to pressure strain. On the other hand, the coating peeled off in diamond component D2, which developed a radius of curvature of R13.5 m due to pressure strain. From this, it was found that diamond components whose radius of curvature becomes R13.5 m or less due to pressure strain cannot be used in areas with pressure differences.

[0059] The radius of curvature due to pressure strain depends on the diameter Φ and thickness t of the diamond component. The beam diameter of the laser light output from the CO2 laser oscillator is approximately Φ10mm to Φ30mm. Therefore, the diameter of the diamond component needs to be at least Φ10mm to Φ30mm, which is the same as the laser beam diameter. The gas pressure of the CO2 laser oscillator is approximately 50 to 300 Torr. When the diameter of the diamond component is Φ30mm and the gas pressure is 50 Torr, the thickness of the diamond component at which the radius of curvature due to pressure strain becomes R13.5m or less is approximately 0.76mm or less. In other words, when using a thin diamond component, it is effective to prevent pressure from being applied in order to prevent coating peeling. Therefore, the laser device 100 according to Embodiment 1 has a particularly significant effect when the thickness t of the diamond component is 0.76mm or less.

[0060] As described above, the laser device 100 according to Embodiment 1 comprises a housing 1 that encloses the laser gas, which is the laser medium; a resonator 2 that includes a plurality of reflectors and amplifies and outputs the laser light; a partition wall 6 that separates the internal space of the housing 1 from the external space of the housing 1 and through which the laser light output from the resonator 2 passes; and electrodes 11 and 12 that are arranged in pairs at intervals in a direction perpendicular to the optical axis of the laser light. The resonator 2 includes a partial reflector 3 that includes at least a diamond material and outputs the amplified laser light to the outside, and a total reflector 4 that is spaced apart from the partial reflector 3 and reflects the laser light. In other words, in the laser device 100 according to Embodiment 1, since a transmissive window 6 is provided, the stress generated in the partial reflector 3 due to the pressure difference between the inside and outside of the housing 1 can be suppressed, and the pressure strain of the partial reflector 3 can be suppressed. Therefore, the laser device 100 according to Embodiment 1 can reduce the adverse effects on the beam characteristics of the laser light output from the laser device 100.

[0061] Embodiment 2. Next, the laser device 101 according to Embodiment 2 will be described. Note that components identical to those in Embodiment 1 are denoted by the same reference numerals, and their descriptions are omitted as appropriate. Figure 12 is a schematic perspective view showing an example of the overall configuration of the laser device according to Embodiment 2. Figure 13 is a schematic plan view showing an example of the overall configuration of the laser device according to Embodiment 2 from the +Y direction. Note that in Figure 12, apertures 15 and 16 shown in Figure 13 are omitted for illustrative purposes.

[0062] As shown in Figures 12 and 13, the laser device 101 according to Embodiment 2 comprises a housing 1, a resonator 2A, electrodes 11 and 12, a heat exchanger 13, a blower 14, apertures 15 and 16, and a transmissive window 6. The housing 1, electrodes 11 and 12, heat exchanger 13, blower 14, apertures 15 and 16, and transmissive window 6 have the same configuration as the laser device 100 according to Embodiment 1.

[0063] The resonator 2A includes a partial reflector 3A, a total reflector 4A, and a folded reflector 5A as multiple reflectors. The partial reflector 3A is formed by orthogonally aligning the reflective surface of a thin diamond member 30 with the reflective surface of a metal mirror 31, and is designed to function as a one-dimensional retroreflector. The material of the metal mirror 31 is, for example, copper, silicon, germanium, or molybdenum. Alternatively, another material such as ZnSe or CaF2 coated with a total reflector film may be used instead of the metal mirror 31.

[0064] The total reflection mirror 4A is a curved mirror, such as a spherical mirror. The folding reflection mirror 5A is positioned on the optical axis L between the partial reflection mirror 3A and the total reflection mirror 4A. The folding reflection mirror 5A is, for example, a flat surface. The folding reflection mirror 5A may be a polarization lock mirror or a curved mirror. The total reflection mirror 4A may also be configured as a one-dimensional retroreflector, as in the total reflection mirror 4 of Embodiment 1.

[0065] In the resonator 2A, the laser beam travels back and forth between the inner surface of the partial reflector 3A and the reflective surface of the total reflector 4A, and the laser gas excited in the discharge region S between the two electrodes 11 and 12 causes the laser beam to oscillate. In other words, the laser beam is amplified. A portion of the amplified laser beam is output from the outer surface of the partial reflector 3A and is output to the outside of the housing 1 through the transmission window 6.

[0066] Next, the configuration of the partial reflector 3A in Embodiment 2 will be described in detail. Figure 14 is a schematic explanatory diagram showing the partial reflector of the laser device according to Embodiment 2. As shown in Figure 14, the diamond member 30 has, for example, a partial reflective coating 30a on one surface and a non-reflective coating 30b on the other surface. Note that the surfaces to which the partial reflective coating 30a and the non-reflective coating 30b are applied may be reversed. The reflective surfaces 31a and 31b of the metal mirror 31 are coated with a total reflective coating such as a gold coating or a dielectric multilayer coating. However, if the reflectivity of the material of the metal mirror 31 itself is high, it is not necessary to apply a total reflective coating to the reflective surfaces 31a and 31b of the metal mirror 31.

[0067] The partial reflector 3A is formed by providing a groove 31c in the metal mirror 31 that is approximately the same thickness as the diamond member 30, and inserting one end of the diamond member 30 almost vertically into the groove 31c. The groove 31c of the metal mirror 31 is formed to a depth such that a portion of the coated part of the diamond member 30 is inside the groove 31c. As a result, the coating of the diamond member 30 is applied at the position where the metal mirror 31 and the diamond member 30 intersect at a right angle. Therefore, even if laser light is shone at the position where the diamond member 30 and the metal mirror 31 intersect, it can still function as a retroreflector.

[0068] Generally, it is technically difficult to apply the partial reflective coating 30a and the anti-reflective coating 30b to the end of the diamond member 30. Therefore, applying the partial reflective coating 30a and the anti-reflective coating 30b to the end of the diamond member 30 increases manufacturing costs. In the partial reflector 3A of Embodiment 2, it is not necessary to apply the partial reflective coating 30a and the anti-reflective coating 30b to the end of the diamond member 30, thus suppressing the increase in manufacturing costs.

[0069] Next, the operation of the partial reflector 3A in Embodiment 2 will be explained. The partial reflective coating 30a applied to the diamond member 30 has a reflectivity of 70%. In Figure 14, L1, indicated by a solid arrow, indicates the portion of the laser light incident on the partial reflector 3A that is incident from the +X side with respect to the optical axis L. In Figure 14, L2, indicated by a dashed arrow, indicates the portion of the laser light incident on the partial reflector 3A that is incident from the -X side with respect to the optical axis L.

[0070] As shown in Figure 14, the laser beam L1 is incident on the partially reflective coating 30a of the diamond member 30, 70% of which is reflected and bent by 90°, moves to the -X side of the optical axis L, is reflected by the reflective surface 31a of the metal mirror 31, and propagates in the opposite direction to the laser beam L2. The 30% of the laser beam L1 that passed through the partially reflective coating 30a is reflected by the reflective surface 31b of the metal mirror 31 and propagates in the +X direction. On the other hand, the laser beam L2 is reflected by the reflective surface 31a of the metal mirror 31, bent by 90°, moves to the +X side of the optical axis L, and is incident on the partially reflective coating 30a of the diamond member 30. 70% of the laser beam L2 incident on the partially reflective coating 30a is reflected and bent by 90° and propagates in the opposite direction to the laser beam L1. The 30% of the laser beam L2 that passed through the partially reflective coating 30a propagates in the +X direction as is.

[0071] 70% of the laser beams L1 and L2 are reflected by the partial reflective coating 30a, and they move to mirror image positions on the opposite side of the optical axis L, propagating in the opposite direction to the incident direction. In other words, the partial reflector 3A acts as a retroreflector that reflects 70% of the incident laser beams L1 and L2. In addition, 30% of the laser beams L1 and L2 pass through the partial reflective coating 30a of the diamond member 30 and travel in the same direction. The diamond member 30 can be used as a partial reflector 3A because it can maintain the beam profiles of the laser beams L1 and L2 almost by making it sufficiently thin. Note that the partial reflective coating 30a applied to the diamond member 30 is shown as an example with a reflectivity of 70%, but it is not limited to this, and can perform the same function with other reflectivity values.

[0072] Figure 15 is a schematic explanatory diagram showing a modified example of the partial reflector of the laser device according to Embodiment 2. As shown in Figure 15, the partial reflector 3A may be configured such that a metal mirror 31 is made up of a plurality of parts 310, 311, and a diamond member 30 is sandwiched between the plurality of parts 310, 311. In this case, it is preferable to make the thickness of the diamond member as thin as possible, for example, 1 mm or less.

[0073] Figure 16 is a cross-sectional view of a laser device according to Embodiment 2, showing a state in which a partial reflector and a transmission window are held in the housing using a holder member. In Figure 16, the area A on the left side of the housing 1, separated by the side wall 10, is the inside of the housing 1 and is the laser gas atmosphere side where the laser gas is sealed. In Figure 16, the area B on the right side is the outside of the housing 1 and is the atmospheric side.

[0074] As shown in Figure 16, the partial reflector 3A and the transmission window 6 are fixed by a cylindrical holder member 7A, which is composed of two cylindrical members 76 and 77, as an example, and can be handled as a single integrated part with the holder member 7A. The two cylindrical members 76 and 77 are combined so that their internal surfaces communicate and are fastened together with screws (not shown). An O-ring 74d is provided between the two cylindrical members 76 and 77. The holder member 7A is held by the adjustment member 8 by fixing the cylindrical member 77 to the adjustment board 8a of the adjustment member 8. An O-ring 81 is provided between the cylindrical member 77 and the adjustment board 8a. The internal surface of the cylindrical member 77 is L-shaped and communicates with the inside of the housing 1. The internal surface of the cylindrical member 76 communicates with the outside of the housing 1. A right-angled optical axis L is positioned inside the cylinder of the holder member 7A.

[0075] The partial reflector 3A is positioned inside the cylindrical member 77 and fixed by a support member 77a, which is part of the cylindrical member 77. The transmission window 6 is positioned inside the holder member 7A and fixed by fitting its outer edge into a groove formed on the inner wall surface of the cylindrical members 76 and 77. An O-ring 74e is provided between the transmission window 6 and the cylindrical member 76. The inside of the holder member 7A is closed by the transmission window 6. The transmission window 6 serves as a partition separating the internal space of the housing 1 from the external space of the housing 1. The transmission window 6 may be installed at an angle so that its inner and outer surfaces are not perpendicular to the optical axis L of the laser beam. The transmission window 6 may also have a wedge on its inner and outer surfaces. The transmission window 6 may also have a curvature on its inner or outer surface.

[0076] The inside of the holder member 7A is configured such that the pressure inside the transparent window 6 is the same as the pressure inside the housing 1. As a result, the transparent window 6 is subjected to the pressure difference between the inside of the housing 1 and the outside air. Note that the configuration in which the partial reflector 3A and the transparent window 6 are moved together by the holder member 7A is not limited to this configuration. The transparent window 6 may be fixed in a different location, and only the partial reflector 3A may be moved. For example, the transparent window 6 may be fixed together with the housing 1, and the transparent window 6 and the partial reflector 3A may be connected by a bellows or the like, so that only the partial reflector 3A can be moved.

[0077] Figure 17 is an explanatory diagram showing a partial reflector of a laser device according to Embodiment 2, where the incident angle θ1 of the laser light incident on the diamond member is 45°. As shown in Figure 17, when the incident angle θ1 of the laser light incident on the diamond member 30 is 45°, the laser light in the region enclosed by wb enters the groove 31c of the metal mirror 31, is not emitted to the outside, and is not propagated in the +X direction. In this case, the portion R1 that is not propagated in the +X direction represents the loss of laser light.

[0078] Figure 18 is an explanatory diagram showing a partial reflector of a laser device according to Embodiment 2, where the incident angle θ2 of the laser beam incident on the diamond member is smaller than 45°. As shown in Figure 18, when the incident angle θ2 of the laser beam incident on the diamond member 30 is smaller than 45°, the laser beam in the region enclosed by wb' enters the groove 31c of the metal mirror 31, is not emitted to the outside, and is not propagated in the +X direction. In this case, the portion R2 that is not propagated in the +X direction represents the loss of laser beam.

[0079] Comparing the portion R1 that does not propagate in the +X direction shown in Figure 17 with the portion R2 that does not propagate in the +X direction shown in Figure 18, it can be seen that reducing the incident angle of the laser beam incident on the diamond member 30 can suppress the loss of laser beam. In other words, in the partial reflector 3A of Embodiment 2, for example, when the thickness of the diamond member 30 cannot be made sufficiently thin, it is not necessary to make the incident angle of the laser beam incident on the metal mirror 31 and the incident angle of the laser beam incident on the diamond member 30 equal to 45°, and it is better to make the incident angle incident on the diamond member 30 smaller and the incident angle incident on the metal mirror 31 larger.

[0080] Embodiment 3. Next, the laser device 102 according to Embodiment 3 will be described. Note that components identical to those in Embodiments 1 and 2 are denoted by the same reference numerals, and their descriptions are omitted as appropriate. Figure 19 is a schematic perspective view showing an example of the overall configuration of the laser device according to Embodiment 3. Figure 20 is a schematic plan view showing an example of the overall configuration of the laser device according to Embodiment 3 from the +Y direction. Note that in Figure 19, apertures 17 and 18 shown in Figure 20 are omitted for illustrative purposes.

[0081] As shown in Figures 19 and 20, the laser device 102 according to Embodiment 3 comprises a housing 1, a resonator 2B, electrodes 11 and 12, a heat exchanger 13, a blower 14, apertures 17 and 18, and a transmissive window 6. The housing 1, electrodes 11 and 12, heat exchanger 13, blower 14, and transmissive window 6 have the same configuration as the laser device 100 according to Embodiment 1.

[0082] The resonator 2B includes a plurality of reflectors: a partial reflector 3B, a total reflector 4B, and folded reflectors 50, 51, and 52. The partial reflector 3B has the same configuration as the partial reflector 3A in Embodiment 2. The total reflector 4B has the same configuration as the total reflector 4 in Embodiment 1.

[0083] The folding mirrors 50, 51, and 52 are positioned on the optical axis L between the partial mirror 3B and the total mirror 4B. The folding mirror 50 may also be a polarization lock mirror. In addition, at least one of the folding mirrors 50, 51, and 52 is a curved mirror. Figures 19 and 20 show an example where the folding mirrors 51 and 52 are curved mirrors.

[0084] An aperture 17 is positioned between the folding reflector 51 and the discharge region S. An aperture 18 is positioned between the folding reflector 52 and the discharge region S. An aperture (not shown) is positioned between the folding reflector 50 and the discharge region S. An aperture (not shown) is positioned between the partial reflector 3B and the discharge region S.

[0085] In the resonator 2B, the laser beam travels back and forth between the inner surface of the partial reflector 3B and the inner surface of the total reflector 4B, and the laser gas excited in the discharge region S between the two electrodes 11 and 12 causes the laser beam to oscillate. In other words, the laser beam is amplified. A portion of the amplified laser beam is output from the outer surface of the partial reflector 3B and is output to the outside of the housing 1 through the transmission window 6.

[0086] In the laser device 102 according to Embodiment 3, the resonator 2B can be used to create a folded structure that folds the optical axis L of the discharge region S, thereby enabling effective utilization of the excited laser gas within the discharge region S and improving the output of the laser light.

[0087] In the laser device 102 according to Embodiment 3, the length of the resonator 2B is increased, which may result in a larger gas prism as described in Embodiment 1. However, in the laser device 102 according to Embodiment 3, since the partial reflector 3B and the total reflector 4B are one-dimensional retroreflectors, even if a gas prism is generated, the position of the optical axis L is fixed in the valley portion of the retroreflector, stabilizing the optical axis L. This provides a more significant effect than when only one of the partial reflector or total reflector is a retroreflector. In a laser processing apparatus equipped with the laser device 102 according to Embodiment 3, fluctuations in the optical axis L are suppressed, enabling stable and high-quality processing.

[0088] Furthermore, the laser device 102 according to Embodiment 3 is not limited to a configuration in which the optical axis L of the discharge region S is folded three times, as shown in Figure 19, but may also be configured in which the optical axis L of the discharge region S is folded four or more times. In addition, in the laser device 102 according to Embodiment 3, in order to more reliably fix the position of the optical axis L in the valley portion of the retroreflectors, which are the partial reflector 3B and the total reflector 4B, the distance from one of the curved mirrors, which are the folded reflectors 50, 51, or 52, to the partial reflector 3B or the total reflector 4B may be set to a value different from the radius of curvature of the curved mirror. Furthermore, the positions of the partial reflector 3B and the total reflector 4B may not be conjugate points to each other.

[0089] Embodiment 4. Next, the laser device 103 according to Embodiment 4 will be described. Note that components identical to those in Embodiments 1 to 3 are denoted by the same reference numerals, and their descriptions are omitted as appropriate. Figure 21 is a schematic plan view showing an example of the overall configuration of the laser device according to Embodiment 4, viewed from the +Y direction.

[0090] As shown in Figure 21, the laser device 103 according to Embodiment 4 comprises a housing 1, a resonator 2C, electrodes 11 and 12, a heat exchanger (not shown), a blower (not shown), and apertures 15 and 16. The housing 1, electrodes 11 and 12, the heat exchanger (not shown), the blower (not shown), apertures 15 and 16, and the transmission window 6 have the same configuration as the laser device 100 according to Embodiment 1. Note that the electrode 12 is not shown in Figure 21.

[0091] The resonator 2C includes a plurality of reflectors: a partial reflector 3C, a total reflector 4C, and a folded reflector 5C. The partial reflector 3C has, for example, the same configuration as the partial reflector 3 of Embodiment 1, but may also have the same configuration as the partial reflector 3A of Embodiment 2. The total reflector 4C has, for example, the same configuration as the total reflector 4 of Embodiment 1, but may also have the same configuration as the total reflector 4A of Embodiment 2. The folded reflector 5C is positioned on the optical axis L between the partial reflector 3C and the total reflector 4C. The folded reflector 5C has a toroidal surface with different radii of curvature in the X-axis direction, which is the direction of the laser gas flow between electrodes 11 and 12, and in the Y-axis direction, which is the direction in which electrodes 11 and 12 face each other. The curvature of the folded reflector 5C is set such that the beam diameter on the partial reflector 3C is larger in the X-axis direction than in the Y-axis direction. Furthermore, in the resonator 2C, the width dw of electrodes 11 and 12 in the X-axis direction, which is orthogonal to the Z-axis direction (which is the optical axis L of the laser beam) and the Y-axis direction (where electrodes 11 and 12 face each other), is configured such that it is less than or equal to the beam radius ω of the laser beam in that X-axis direction.

[0092] In the laser device 103 according to Embodiment 4, the gain is concentrated at the center of the laser beam, thereby reducing the loss of the laser beam. This makes it easier to obtain a unimodal beam profile with high intensity at the center, as shown in the waveform in Figure 21. As a result, the laser device 103 according to Embodiment 4 has improved laser beam focusing characteristics, and when applied to a laser drilling device, it enables drilling of smaller diameter holes.

[0093] In the laser device 103 according to Embodiment 4, the folded reflector 5C is configured to have a toroidal surface, and the width dw of the electrodes 11 and 12 is set to be less than or equal to the beam radius ω of the laser light. However, the above effects can be obtained even if only one of these configurations is used. In addition, the resonator 2C in Embodiment 4 may be configured with multiple folded reflectors 5C, as in the resonator 2B of Embodiment 3.

[0094] Embodiment 5. Next, the laser device 104 according to Embodiment 5 will be described. Note that components identical to those in Embodiments 1 to 4 are denoted by the same reference numerals, and their descriptions are omitted as appropriate. Figure 22 is a schematic perspective view showing an example of the overall configuration of the laser device according to Embodiment 5. Note that the aperture is omitted in Figure 22 for illustrative purposes.

[0095] As shown in Figure 22, the laser device 104 according to Embodiment 5 comprises a housing 1, a resonator 2D, electrodes 11 and 12, a heat exchanger 13, a blower 14, and an aperture (not shown). The laser device 104 according to Embodiment 5 does not have the transmission window 6 described in Embodiments 1 to 4. The housing 1, electrodes 11 and 12, heat exchanger 13, blower 14, and aperture have the same configuration as the laser device 102 according to Embodiment 3.

[0096] The resonator 2D includes a plurality of reflectors: a partial reflector 3D, a total reflector 4D, and folded reflectors 50, 51, and 52. The partial reflector 3D has a metal mirror 32 and a ZnSe mirror 33, and is a one-dimensional retroreflector formed by orthogonally aligning the reflective surface 32a of the metal mirror 32 and the reflective surface 33a of the ZnSe mirror 33. The shape of the ZnSe mirror 33 is, for example, a triangular prism. The total reflector 4D and the folded reflectors 50, 51, and 52 have the same configuration as the laser device 102 according to Embodiment 3. That is, the total reflector 4D is a one-dimensional retroreflector.

[0097] Figure 23 is a schematic explanatory diagram showing a partial reflector of a laser device according to Embodiment 5. As shown in Figure 23, the partial reflector 3D is installed so that the reflective surface 32a of the metal mirror 32 and the reflective surface 33a of the ZnSe mirror 33 intersect almost perpendicularly. The reflective surface 32a of the metal mirror 32 and the reflective surface 33a of the ZnSe mirror 33 constitute a one-dimensional retroreflector. The reflective surface 33a of the ZnSe mirror 33 is coated with a partial reflection coating. The surface 33b of the ZnSe mirror 33 that emits laser light is coated with an anti-reflective coating. The surface 33c of the ZnSe mirror 33 facing the metal mirror 32 may be coated with an anti-reflective coating or a total reflection coating, or it may not be coated. Furthermore, the reflective surface 32a of the metal mirror 32 and the reflective surface 32b of the metal mirror 32 facing the surface 33c of the ZnSe mirror 33 are coated with a total reflection film such as a gold coating or a dielectric multilayer coating. However, if the reflectivity of the material of the metal mirror 32 itself is high, it is not necessary to apply a total reflection film to the reflective surfaces 32a and 32b of the metal mirror 32.

[0098] Next, the operation of the partial reflector 3D in Embodiment 5 will be explained. The partial reflective coating applied to the reflective surface 33a of the ZnSe mirror 33 has a reflectivity of 70%. In Figure 23, L1, indicated by the solid arrow, indicates the portion of the laser light incident on the partial reflector 3D that is incident from the +X side with respect to the optical axis L. In Figure 23, L2, indicated by the dashed arrow, indicates the portion of the laser light incident on the partial reflector 3D that is incident from the -X side with respect to the optical axis L.

[0099] As shown in Figure 23, the laser beam L1 is incident on the partially reflective coated portion, which is the reflective surface 33a of the ZnSe mirror 33. 70% of it is reflected and bent by 90°, moving to the -X side of the optical axis L, where it is reflected by the reflective surface 32a of the metal mirror 32 and propagates in the opposite direction to the laser beam L2. The remaining 30% of the laser beam L1 that passes through the reflective surface 33a of the ZnSe mirror 33 is reflected by the reflective surface 32b of the metal mirror 32 or the surface 33c of the ZnSe mirror 33 and propagates in the +X direction. Meanwhile, the laser beam L2 is reflected by the reflective surface 32a of the metal mirror 32, bent by 90°, moving to the +X side of the optical axis L, and incident on the partially reflective coated portion, which is the reflective surface 33a of the ZnSe mirror 33. 70% of the laser beam L2 incident on the reflective surface 33a of the ZnSe mirror 33 is reflected and bent by 90° and propagates in the opposite direction to the laser beam L1. 30% of the laser light L2 that passes through the reflective surface 33a of the ZnSe mirror 33 propagates in the +X direction.

[0100] Laser beams L1 and L2 are both reflected 70% by the reflective surface 33a of the ZnSe mirror 33, moving to their respective mirror image positions on the opposite side of the optical axis L, and propagating in the opposite direction to the incident direction. In other words, the partial reflector 3D acts as a retroreflector that reflects 70% of the incident laser beams L1 and L2. In addition, 30% of both laser beams L1 and L2 are transmitted through the reflective surface 33a of the ZnSe mirror 33 and travel in the same direction. The ZnSe mirror 33 can be used as a partial reflector 3D because it can maintain the beam profiles of the laser beams L1 and L2 almost perfectly. Note that the partial reflective coating applied to the reflective surface 33a of the ZnSe mirror 33 is shown as an example with a reflectivity of 70%, but it is not limited to this, and can perform the same function with other reflectivity values.

[0101] Figure 24 is a cross-sectional view of a laser device according to Embodiment 5, showing a state in which a partial reflector is held in the housing using a holder member. In Figure 24, the area A on the left side of the housing 1, separated by the side wall 10, is the inside of the housing 1 and is the laser gas atmosphere side where the laser gas is sealed. In Figure 24, the area B on the right side is the outside of the housing 1 and is the atmospheric side.

[0102] As shown in Figure 24, the partial reflector 3D is fixed by a cylindrical holder member 7B, which is formed by combining two cylindrical members 78 and 79, as an example, and can be handled as a single integrated part with the holder member 7B. The two cylindrical members 78 and 79 are combined so that their internal tubes communicate in an L-shape and are fastened together with screws (not shown). An O-ring 74g is provided between the two cylindrical members 78 and 79. The holder member 7B is held by the adjustment member 8 by fixing the cylindrical member 79 to the adjustment substrate 8a of the adjustment member 8. An O-ring 81 is provided between the cylindrical member 79 and the adjustment substrate 8a. The internal tube of the cylindrical member 79 communicates with the inside of the housing 1. The internal tube of the cylindrical member 78 communicates with the outside of the housing 1. A right-angled optical axis L is positioned inside the tube of the holder member 7B.

[0103] The partial reflector 3D is positioned inside the cylindrical member 79 and fixed by a support member 79a, which is part of the cylindrical member 79. The inside of the holder member 7B is sealed by the ZnSe mirror 33 of the partial reflector 3D. Specifically, the open end of the cylindrical member 78 is sealed by the surface 33b of the ZnSe mirror 33. An O-ring 74f is provided between the surface 33b of the ZnSe mirror 33 and the cylindrical member 78. In other words, the ZnSe mirror 33 acts as a partition wall separating the internal space of the housing 1 from the outside of the housing 1.

[0104] The inside of the holder member 7B is configured such that the pressure inside the ZnSe mirror 33 is the same as the pressure inside the housing 1. As a result, the ZnSe mirror 33 is subjected to a pressure difference between the inside of the housing 1 and the outside air.

[0105] In the laser device 104 according to Embodiment 5, similar to Embodiment 3, the length of the resonator 2D increases, which may lead to a larger gas prism as described in Embodiment 1. However, in the laser device 104 according to Embodiment 5, since the partial reflector 3D and the total reflector 4D are one-dimensional retroreflectors, even if a gas prism is generated, the position of the optical axis L is fixed in the valley portion of the retroreflector, stabilizing the optical axis L. This provides a more significant effect than when only one of the partial reflector or total reflector is a retroreflector. In a laser processing apparatus equipped with the laser device 104 according to Embodiment 5, fluctuations in the optical axis L are suppressed, enabling stable and high-quality processing.

[0106] Furthermore, the laser device 104 according to Embodiment 5 is not limited to a configuration in which the optical axis L of the discharge region S is folded three times, as shown in Figure 22, but may also be configured in which the optical axis L of the discharge region S is folded four or more times. In addition, in the laser device 104 according to Embodiment 5, in order to more reliably fix the position of the optical axis L in the valley portion of the retroreflectors, which are the partial reflector 3D and the total reflector 4D, the distance from one of the curved mirrors, which are the folded reflectors 50, 51, or 52, to the partial reflector 3D or the total reflector 4D may be set to a value different from the radius of curvature of the curved mirror. Moreover, the positions of the partial reflector 3D and the total reflector 4D may not be conjugate points to each other.

[0107] The configurations shown in the above embodiments are merely examples and can be combined with other known technologies, or the embodiments themselves can be combined. Furthermore, it is possible to omit or modify parts of the configuration without departing from the spirit of the invention. [Explanation of Symbols]

[0108] 1,200a housing, 2,2A,2B,2C,2D resonator, 3,3',3A,3B,3C,3D partial reflector, 3a inner surface, 3b outer surface, 4,4A,4B,4C,4D total reflector, 5,5A,5C,50,51,52 folding reflector, 6 transmission window, 7,7A,7B Holder member, 7a through hole, 8 adjustment member, 8a adjustment board, 8b fixed part, 10 side wall, 10a opening, 11,12 electrode, 13 heat exchanger, 14 blower, 15,16,17,18 aperture, 30 diamond member, 30a partial reflective coating, 30b non-reflective coating, 31,32 Metal mirror, 31a, 31b, 32a, 32b, 33a Reflective surface, 31c Grooves, 33 ZnSe mirrors, 33b, 33c Surfaces, 70, 71, 72, 76, 77, 78, 79 Cylindrical members, 73 Screws, 74a, 74b, 74c, 74d, 74e, 74f, 74g, 80, 81 O-rings, 75 Valves, 77a, 79a Support members, 82 Angle adjustment mechanisms, 100, 101, 102, 103, 104 Laser devices, 200 Laser processing machines, 300 Laser processing equipment, 310, 311 Parts, 400 Workpieces, I1 First internal space, I2 Second internal space, L Optical axis, Lb Laser light, S Discharge region.

Claims

1. A housing that contains the laser gas, which is the laser medium, A resonator containing multiple reflectors that amplifies and outputs laser light, A partition wall separates the internal space of the housing from the external space of the housing, and has a transparent window through which the laser light output from the resonator passes, It comprises electrodes arranged in pairs at intervals perpendicular to the optical axis of the laser beam, The resonator includes a partial reflector that contains at least a diamond material and outputs the amplified laser light to the outside, and a total reflector that is positioned at a distance from the partial reflector and reflects the laser light. The aforementioned partial reflector consists of a one-dimensional retroreflector formed by orthogonally aligning the reflective surface of the diamond member and the reflective surface of the metal mirror. Of the plurality of reflectors, at least one of the reflectors other than the partial reflector has a curved reflective surface. A laser device characterized by the following features.

2. The resonator further comprises a folded mirror having a curvatured reflective surface, which is positioned on the optical axis between the partial mirror and the total mirror. The aforementioned total reflection mirror is considered to be a one-dimensional retroreflecting mirror. The laser apparatus according to feature 1.

3. The aforementioned folding mirror has toroidal surfaces with different radii of curvature in the direction of the gas flow of the laser gas flowing between the electrodes and in the direction in which the electrodes face each other. The laser apparatus according to feature 2.

4. The electrodes are configured such that the width in a direction perpendicular to the direction of the optical axis of the laser beam and the direction in which the electrodes face each other is less than or equal to the beam radius of the laser beam in that direction. The laser apparatus according to any one of claims 1 to 3.

5. The partial reflector is positioned such that the incident angle of the laser beam incident on the diamond member is less than 45°. The laser apparatus according to feature 1.

6. The diamond component is coated with a partially reflective film having a reflectivity of 11% or more. The laser apparatus according to claim 1, 2, 3, or 5.

7. A laser apparatus according to claim 1, 2, 3, or 5, The laser processing machine comprises a laser device that focuses the laser light emitted from the laser device and irradiates it onto a workpiece, A laser processing apparatus characterized by the following features.

8. A method for manufacturing an electronic component by focusing laser light emitted from a laser device according to claim 1, 2, 3, or 5 with a laser processing machine and irradiating it onto a workpiece, The laser light is amplified in the resonator, and the laser light is output from a partial reflector, which includes a diamond material in at least a portion of the plurality of reflectors. The laser light is then emitted from the laser device by passing it through a transparent window, which serves as a partition separating the internal space of the housing from the external space of the housing. A method for manufacturing electronic components, characterized by the following:

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