Semiconductor laser device, and laser apparatus and laser processing apparatus including the same

Abstract

To provide a semiconductor laser device capable of suppressing a deposition rate of a deposit adhering to a light emission end face of a semiconductor laser element and suppressing deterioration of operation reliability.SOLUTION: The laser oscillator 10 includes at least a laser module 12 having a laser diode bar 12A and a first housing 11 that houses the laser module 12. Each of the plurality of emitters 12A provided in the laser diode bar 12A3 emits the first laser beam LBE, and the wave range of the first laser beam LBE is equal to or less than 550nm. At least during operation of the laser diode bar 12A, the volumetric water content inside the first housing 11 is kept below 200ppmv.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a semiconductor laser device, and a laser device and a laser processing device equipped with the semiconductor laser device. [Background technology]

[0002] In recent years, expectations for laser processing have been increasing for various materials such as copper, gold, and resin. For example, in the automotive industry, there are demands for electrification, miniaturization, high rigidity, greater design freedom, and improved productivity, and expectations for laser processing are high. To achieve highly productive processing, a laser light source that can generate highly efficient, high-power laser light is required. A semiconductor laser element is known as a laser light source suitable for this requirement. In particular, to increase the output of laser light, a laser module equipped with a laser diode bar having multiple emitters that emit laser light is useful.

[0003] When a semiconductor laser element emits high-power laser light, contaminants may adhere to the light-emitting end face of the semiconductor laser element and accumulate as deposits. Siloxane compounds with Si-O-Si bonds are known as typical contaminants. When a siloxane compound in the atmosphere is irradiated with laser light, a photochemical reaction occurs, and the decomposition products produced by this reaction adhere to the light-emitting end face and form deposits. This photochemical reaction progresses more rapidly as the laser light output power and wavelength are shorter. Therefore, in semiconductor laser elements that emit high-power, short-wavelength laser light, for example, blue laser light, the thickness of deposits that accumulate on the light-emitting end face increases.

[0004] When the thickness of this deposit increases, the deposit absorbs part of the laser light, reducing the output power of the laser light that can be extracted to the outside. Furthermore, the optical characteristics of the laser light degrade when it passes through the deposit. Furthermore, the deposit absorbs the laser light and generates heat, raising the temperature of the light-emitting end facet and reducing the operational reliability of the semiconductor laser element. In extreme cases, part of the light-emitting end facet melts, causing the semiconductor laser element to break down.

[0005] Therefore, a configuration has been proposed in which the atmosphere inside a package in which a semiconductor laser element that emits blue laser light is hermetically sealed is controlled to reduce the adhesion of contaminants to the light-emitting end face and suppress the occurrence of deposits.

[0006] For example, Patent Document 1 discloses a configuration in which the inside of a package is filled with a sealed gas containing oxygen and at least one of a halogen gas and a halogen compound gas, thereby suppressing the occurrence of deposits. Patent Document 2 discloses a configuration in which the oxygen concentration of the inert gas sealed inside the package is set to 15% or more and less than 30%, and the dew point is set to -15°C or more and -5°C or less, thereby suppressing the occurrence of deposits.

[0007] In addition to these, Patent Document 3 discloses a configuration in which gas is introduced into a container that houses a semiconductor laser element and a lens holder that holds a lens, and then the gas is exhausted to the outside of the container, thereby preventing dust and the like from entering the inside of the housing. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-298171 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-88066 [Patent Document 3] Patent No. 4055353 Summary of the Invention [Problem to be solved by the invention]

[0009] However, according to the investigations of the present inventors, it has been found that the deposition rate of the deposits adhering to the light-emitting end face of the semiconductor laser element is greatly dependent on the siloxane concentration and volumetric water content of the internal atmosphere of the container in which the semiconductor laser element is housed.

[0010] The present disclosure has been made in consideration of these points, and its purpose is to provide a semiconductor laser device that can suppress the deposition rate of deposits adhering to the light-emitting end face of a semiconductor laser element and suppress a decrease in operational reliability, as well as a laser device and laser processing device equipped with the same. [Means for solving the problem]

[0011] In order to achieve the above object, the semiconductor laser device according to the present disclosure is a semiconductor laser device including at least a semiconductor laser element and a first housing that houses the semiconductor laser element, wherein the semiconductor laser element emits a first laser beam, the wavelength range of the first laser beam is 550 nm or less, and the volumetric moisture content inside the first housing is maintained at 200 ppmv or less at least during operation of the semiconductor laser element.

[0012] The laser device according to the present disclosure comprises at least the semiconductor laser device, an airflow circulation mechanism connected to the first housing and circulating airflow inside the first housing, and a control unit that controls the operation of at least the airflow circulation mechanism, and is characterized in that the control unit operates the airflow circulation mechanism to control the volumetric water content or both the volumetric water content and the siloxane concentration inside the first housing.

[0013] The laser processing apparatus according to the present disclosure is characterized by comprising at least the laser device, an optical fiber connected to the laser device and guiding laser light including the first laser light, and a laser head connected to the optical fiber and emitting the laser light received from the optical fiber. [Effects of the Invention]

[0014] According to the present disclosure, it is possible to suppress the deposition rate of deposits adhering to the light-emitting end face of a semiconductor laser element, and to suppress a decrease in operational reliability. [Brief explanation of the drawings]

[0015] [Figure 1]1 is a schematic configuration diagram of a laser processing device according to a first embodiment. [Figure 2A] FIG. 2 is a schematic diagram showing the flow of dry air generation in the laser processing device. [Figure 2B] FIG. 10 is a schematic diagram showing a state in which the volumetric moisture content in dry air in the laser processing device is maintained. [Figure 2C] FIG. 2 is a schematic diagram showing the change in volumetric moisture content in dry air over time after the dry air is generated. [Figure 3] FIG. 2 is a schematic diagram showing the internal configuration of a laser oscillator. [Figure 4] FIG. 1 is a perspective view of a laser diode bar. [Figure 5] 10 is a cross-sectional photograph of the laser diode bar after the output of the second laser light has decreased below a predetermined value. [Figure 6] FIG. 10 is a graph showing the relationship between siloxane concentration and SiOx deposition rate. [Figure 7] FIG. 10 is a graph showing the continuous test time dependence of the laser light output fluctuation rate due to differences in the amount of moisture in an atmosphere containing a cyclic siloxane compound. [Figure 8] FIG. 10 is a graph showing the continuous test time dependence of the laser light output fluctuation rate due to differences in the amount of moisture in an atmosphere containing a linear siloxane compound. [Figure 9] FIG. 10 is a graph showing the relationship between the volumetric water content and the SiOx deposition rate. [Figure 10] FIG. 1 is a schematic diagram showing a conventional speculation model regarding the reaction between a cyclic siloxane compound and moisture. [Figure 11] FIG. 1 is a schematic diagram showing a speculative model for the reaction of a cyclic siloxane compound and a linear siloxane compound with moisture. [Figure 12] FIG. 10 is a diagram showing the allowable range of volumetric moisture content. [Figure 13] FIG. 10 is a diagram showing the allowable range of volumetric water content according to Modification 1. [Figure 14] FIG. 10 is a diagram showing the allowable range of volumetric water content according to Modification 2. [Figure 15] FIG. 10 is a diagram showing the allowable range of volumetric water content according to Modification 3. [Figure 16] FIG. 10 is a diagram showing the allowable range of volumetric water content according to Modification 4. [Figure 17] FIG. 10 is a schematic diagram illustrating the internal configuration of a laser head according to a second embodiment. [Figure 18] FIG. 1 is a diagram showing the relationship between the bond dissociation energy of a binding group and the wavelength of light that involves a two-photon absorption process. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0017] (Embodiment 1) [Laser processing equipment configuration] FIG. 1 is a schematic diagram of a laser processing device according to the first embodiment.

[0018] The laser processing apparatus 400 includes a plurality of laser oscillators 10, a beam combiner 20, a focusing optical unit 30, an airflow circulation mechanism 40, a control unit 60, a power supply 70, a fourth housing 80, an optical fiber 90, and a laser head 100. The configuration of the laser oscillators 10 will be described later.

[0019] The plurality of laser oscillators 10, the beam combiner 20, and the focusing optical unit 30 are housed inside a fourth housing 80. A portion of the optical fiber 90 is also housed inside the fourth housing 80. The space inside the fourth housing 80 may be referred to as a light source chamber 200.

[0020] Meanwhile, a portion of the optical fiber 90, the laser head 100, and the workpiece W are housed inside a fifth housing 310. Although not shown, all or part of a mechanism for placing and holding the workpiece W is also housed inside the fifth housing 310. The space inside the fifth housing 310 may be referred to as a processing chamber 300. A fifth dew-point meter 320 is also arranged inside the fifth housing 310.

[0021] The fifth dew-point meter 320 measures the dew-point temperature inside the fifth housing 310. The dew-point temperature is the temperature at which the water vapor pressure in the gas equals the saturated water vapor pressure of water. As shown in this embodiment, when the pressure of the atmosphere through which the processing laser beam LB passes is atmospheric pressure, the dew-point temperature is equal to the temperature of the gas (dry-bulb temperature) at which the water vapor in the gas begins to condense. As is clear from these, when the amount of water vapor in the gas is constant, the dew-point temperature changes depending on the temperature of the gas (dry-bulb temperature). When the dry-bulb temperature of the gas is constant, the dew-point temperature changes depending on the water vapor pressure in the gas, in other words, the amount of moisture in the gas. The fifth dew-point meter 320 may be configured as a temperature-humidity sensor to measure the dew-point temperature and dry-bulb temperature inside the fifth housing 310. The first to fourth and sixth dew-point meters 16, 22, 32, 44, and 150 described below may also be configured as temperature-humidity sensors.

[0022] The beam combiner 20 has a plurality of optical components (not shown) inside a second housing 21, and combines the second laser beams LB emitted from the plurality of laser oscillators 10. M are combined into a single processing laser beam LB. A second dew point meter 22 is also disposed inside the second housing 21. The second dew point meter 22 has the same configuration as the fifth dew point meter 320, and measures the dew point temperature inside the second housing 21.

[0023] The focusing optical unit 30 has at least a focusing lens (not shown) inside the third housing 31, and focuses the processing laser light LB emitted from the beam combiner 20 and optically couples it to the incident end of the optical fiber 90. Also, a third dew-point meter 32 is arranged inside the third housing 31. The third dew-point meter 32 has the same configuration as the fifth dew-point meter 320, and measures the dew-point temperature inside the third housing 31.

[0024] The airflow circulation mechanism 40 supplies dry air, the volumetric moisture content and siloxane concentration of which have been adjusted, to each of the first to third and fifth housings 11, 21, 31, 310. The dry air that has flowed inside each housing is collected by the airflow circulation mechanism 40 and is supplied again to the inside of each housing. The configuration and operation of the airflow circulation mechanism 40 will be described in detail later. The volumetric moisture content is the amount of water vapor contained in the atmosphere expressed as a volume fraction. The volumetric moisture content is Pv, and the total pressure of the atmosphere is P. A When the water vapor pressure in the atmosphere is Pw, the volumetric water content Pv satisfies the relationship shown in equation (1).

[0025] Pv(ppmv)=10 6 ×(Pw / (P A -Pw)) ···(1) The control unit 60 has at least a calculation unit 61, a storage unit 62, and a display unit 63. The calculation unit 61 is made up of one or more central processing units (CPUs), and the storage unit 62 is made up of semiconductor memory such as a random access memory (RAM) or a read only memory (ROM). The storage unit 62 may further have a hard disk drive (HDD), a solid state drive (SSD), or the like.

[0026] The control unit 60 controls the laser oscillation of each laser oscillator 10 by supplying control signals such as output voltage and on-time to the power supply 70. It is also possible to control the laser oscillation of each laser oscillator 10 individually. For example, the laser oscillation output, on-time, etc. may be made different for each laser oscillator 10. In the following description, an apparatus consisting of one or more laser oscillators 10, a beam combiner 20, a focusing optical unit 30, an airflow circulation mechanism 40, and a control unit 60 may be referred to as a laser apparatus 160. When the laser apparatus 160 is provided with only one laser oscillator 10, the beam combiner 20 may be omitted from the laser apparatus 160. When it is desired to increase the output of the processing laser light LB, a plurality of laser oscillators 10 may be provided as shown in FIG. 1, and the second laser light LB emitted from each of the laser oscillators 10 may be combined. M(see FIG. 3) are combined by a beam combiner 20 to obtain a high-power laser beam LB for processing.

[0027] The control unit 60 also controls the operation of the airflow circulation mechanism 40. Specifically, the calculation unit 61 calculates the volumetric moisture content inside each housing based on the dew-point temperatures measured by the first to sixth dew-point meters 16, 22, 32, 44, 320, and 150. The control unit 60 also controls the operation of the airflow circulation mechanism 40 based on the calculation results so that the volumetric moisture content inside each housing is equal to or less than a predetermined value and so that the dew-point temperatures are equal to or less than another predetermined value.

[0028] The storage unit 62 stores a laser processing program. The storage unit 62 also stores a table or text file describing the relationship between the dew point temperature and the volumetric moisture content. The table or the like may also describe the relationship between the dew point temperature and the relative humidity, etc.

[0029] The display unit 63 simultaneously displays, for example, processing parameters during laser processing. The display unit 63 usually includes a display device such as a liquid crystal display or an organic EL display.

[0030] As described above, the power supply 70 supplies power for laser oscillation to each of the plurality of laser oscillators 10. The power supplied to each laser oscillator 10 may be different in accordance with a command from the control unit 60. Furthermore, if the laser head 100 is held by a manipulator (not shown) and is movable, the power supply 70 may supply power to the manipulator. Note that power may be supplied to the manipulator from a separate power supply (not shown).

[0031] The optical fiber 90 has at least a core and a cladding (not shown). The core is provided at the axial center of the optical fiber 90 and functions as an optical waveguide that guides the processing laser light LB incident from the focusing optical unit 30 to the laser head 100. The cladding is provided so as to surround the outer periphery of the core and functions as an optical confinement layer that confines the processing laser light LB inside the core.

[0032] The laser head 100 irradiates the processing laser light LB transmitted through the optical fiber 90 toward the outside. For example, in the laser processing apparatus 400 shown in Fig. 1, the processing laser light LB is irradiated toward a workpiece W, which is an object to be processed and placed at a predetermined position. In this manner, the workpiece W is laser processed.

[0033] In this embodiment, four laser oscillators 10 are mounted on the laser processing apparatus 400, but this is not particularly limited. The number of laser oscillators 10 mounted can be changed as appropriate depending on the output specifications required for the laser processing apparatus 400 and the output specifications of each laser oscillator 10. For example, there may be one laser oscillator 10. In this case, the second laser light LB M becomes the processing laser light LB. As described above, the beam combiner 20 is omitted.

[0034] According to the laser processing apparatus 400 of this embodiment, the workpiece W can be laser processed using a high-power processing laser beam LB. This allows, for example, drilling or cutting a thick plate of the workpiece W in a short time. Furthermore, by using the optical fiber 90, it becomes easy to guide the processing laser beam LB to the workpiece W located away from the light source chamber 200. Furthermore, by providing the laser head 100 at the tip of the optical fiber 90, it becomes easy to irradiate the processing laser beam LB at a desired position on the workpiece W.

[0035] [Configuration and operation of the airflow circulation mechanism] Fig. 2A is a schematic diagram showing the flow of dry air generation in a laser processing apparatus. Fig. 2B is a schematic diagram showing a state in which the volumetric moisture content of dry air in a laser processing apparatus is maintained. For ease of explanation, Figs. 2A and 2B illustrate the flow of dry air related to the first housing 11 of the laser oscillator 10, but dry air is similarly supplied from the airflow circulation mechanism 40 to and collected from the second, third, and fifth housings 21, 31, and 310.

[0036] As shown in FIGS. 2A and 2B , the airflow circulation mechanism 40 includes an air pump 41, a first chemical filter 42, a desiccant 43, and a fourth dew point meter 44. These components are connected by a first pipe 47. A dust filter (not shown) may be provided between the air pump 41 and the desiccant 43. The airflow circulation mechanism 40 is also connected to a motive air supply mechanism 50. The motive air supply mechanism 50 includes a dry air generation unit 51 and a second chemical filter 52. These components are connected by a second pipe 53. The second chemical filter 52 is connected to an inlet 49A provided in the first pipe via the second pipe 53 and a fourth gas valve 54. The motive air supply mechanism 50 can be considered a part of the airflow circulation mechanism 40. Dust filters (not shown) may be provided before and after the second chemical filter 52.

[0037] When the airflow circulation mechanism 40 starts operating, as shown in FIG. 2A, the motive air supply mechanism 50 operates to draw motive air used in the environment where the laser processing apparatus 400 is installed into the dry air generation unit 51. The dry air generation unit 51 generates dry air by reducing the moisture content of the motive air. The generated dry air is supplied to the second chemical filter 52, where organic matter such as siloxane is removed, and then supplied to the second pipe 53. When the fourth gas valve 54, located between the second pipe 53 and the inlet 49A, is opened, the dry air that has passed through the inlet 49A has further organic matter removed by the first chemical filter 42, and moisture is adsorbed and removed by the desiccant 43. A fourth dew point meter 44 is directly connected between the air pump 41 and the first chemical filter 42.

[0038] The dry air that has passed through the desiccant 43 flows into the inside of the first housing 11 through the air inlet 11A and further flows into the first pipe 47 connected to the exhaust outlet 11B. The dry air then flows from the outlet 49B through the fourth gas valve 54, which is in an open state, into the second pipe 53, and is then purged outside the motive air supply mechanism 50.

[0039] After a predetermined time has elapsed, the fourth gas valve 54 connected to the inlet 49A and the outlet 49B is closed, and the air pump 41 is driven. As a result, as shown in FIG. 2B , the dry air pumped under pressure from the air pump 41 flows into the first housing 11 through the aforementioned path. The dry air flowing out from the exhaust port 11B flows through the first piping 47 into the air pump 41, and is pumped again toward the first housing 11.

[0040] 2B , the dew point temperature of the dry air is measured by each of the first dew point meter 16 and the fourth dew point meter 44 inside the first housing 11. Based on the dew point temperature measured by the fourth dew point meter 44, the control unit 60 calculates the volumetric moisture content of the dry air flowing through the first piping 47. Based on the calculation result, the control unit 60 also controls the operation of the airflow circulation mechanism 40 so that the volumetric moisture content of the dry air becomes equal to or less than a predetermined value. For example, the motor (not shown) that drives the air pump 41 is operated at maximum rotation speed until the volumetric moisture content of the dry air becomes equal to or less than the predetermined value.

[0041] As described above, the control unit 60 calculates the volumetric moisture content inside the first housing 11 based on the dew point temperature measured by the first dew point meter 16. Even if the volumetric moisture content of the dry air flowing through the first piping 47 is equal to or less than a predetermined value, if the volumetric moisture content inside the first housing 11 exceeds the predetermined value, the control unit 60 controls the operation of the airflow circulation mechanism 40 so that the volumetric moisture content inside the first housing 11 is equal to or less than the predetermined value. That is, in the state shown in FIG. 2B , the volumetric moisture content in the dry air is maintained equal to or less than a predetermined design value.

[0042] FIG. 2C is a schematic diagram showing the change over time in the volumetric moisture content of dry air after the dry air is generated.

[0043] 2C is the state in which the laser processing apparatus 400 is in the state shown in FIG. 2A, that is, the state in which the dry air generated in the dry air generation unit 51 is circulated through the first piping 47 and flows inside the first housing 11. Area B is the state in which the laser processing apparatus 400 is in the state shown in FIG. 2B, that is, the state in which the dry air pressurized by the air pump 41 is circulated through the first piping 47 and flows inside the first housing 11.

[0044] As shown in FIG. 2C, in region A, initially, the volumetric moisture content of the dry air in the first pipe 47 is at the same level as the atmosphere. As time passes, the first pipe 47 and the first housing 11 are purged with dry air, and the volumetric moisture content of the dry air in the first pipe 47 falls below the predetermined value described above. Hereinafter, this predetermined value may be referred to as the design value. The volumetric moisture content falls below the design value. When the system transitions from region A to region B and dry air is pumped out from the air pump 41, the volumetric moisture content is maintained at a level below the design value.

[0045] 2A and 2B, the concentration of siloxane contained in dry air can be evaluated. As shown in FIGS. 2A and 2B, a second gas valve 46B is provided in a first pipe 47 connecting an exhaust port 11B of the first housing 11 and an outlet 49B. A bypass path is provided to bypass the second gas valve 46B, and a collection pipe 45 and a flow meter 48 are inserted in the bypass path. A first gas valve 46A is provided in the bypass path connecting the upstream side of the second gas valve 46B and the flow meter 48. A third gas valve 46C is provided in the bypass path connecting the collection pipe 45 and the downstream side of the second gas valve 46B.

[0046] During normal operation, the first gas valve 46A and the third gas valve 46C are closed, and the second gas valve 46B is open, so that dry air flows through the first pipe 47 but does not flow through the bypass path.

[0047] When evaluating the siloxane concentration, the first to third gas valves 46A, 46B, and 46C are operated while the laser oscillator 10 is stopped to allow dry air to flow through the bypass path. Specifically, the second gas valve 46B is closed, and the first gas valve 46A and the third gas valve 46C are opened. At this time, the flow rate of the dry air flowing into the collection tube 45 is measured by the flow meter 48. Note that because the pressure loss of the dry air in the collection tube 45 is large, in some cases the second gas valve 46B is slightly opened while the dry air is flowed into the collection tube 45. In this case, the openings of the first gas valve 46A and the third gas valve 46C are appropriately adjusted so that the measurement value of the flow meter 48 is within a specified range.

[0048] After the dry air has been flowing for a predetermined period of time, the first to third gas valves 46A, 46B, and 46C are operated again to return to the normal operating state described above. The collection tube 45 is removed and attached to a gas chromatography mass spectrometer (GC-MS) (not shown), and the siloxane concentration in the dry air collected by the collection tube 45 is measured.

[0049] The organic adsorbents (not shown) provided in the first chemical filter 42 and the second chemical filter 52 are replaced periodically at a predetermined replacement frequency. However, if the siloxane concentration measured by GC-MS exceeds a predetermined value, operation of the laser processing apparatus 400 is stopped, and the first chemical filter 42, the second chemical filter 52, or both are replaced even if the regular replacement time has not yet been reached.

[0050] [Configuration of laser oscillator and laser diode bar] Fig. 3 is a schematic diagram showing the internal configuration of a laser oscillator. Fig. 4 is a perspective view of a laser diode bar. For ease of explanation, Fig. 3 shows a simplified view of the interior of the laser oscillator 10. Similarly, Fig. 4 shows a simplified view of the configuration of the laser diode bar 12A and the emitters 12A3, which differ from the actual configurations. For example, the number of laser modules 12 and the number of emitters 12A3 in the laser diode bar 12A differ from the actual configurations.

[0051] As shown in FIG. 3, a laser oscillator (semiconductor laser device) 10 has a plurality of laser modules 12, a diffraction grating 13, and an external cavity mirror 15, which are arranged inside a first housing 11 while maintaining a predetermined positional relationship with each other. The laser modules 12 have at least laser diode bars 12A (see FIG. 4) and a support part (not shown) for supporting the laser diode bars (semiconductor laser elements) 12A. The support part also has electrodes (not shown) for applying current to the laser diode bars 12A, and also has the function of cooling the laser diode bars 12A. The laser modules 12 also emit a first laser light LB E The optical component (not shown) is disposed in the optical path of the first laser beam LB (see FIG. 4). E The first laser beam LB is collimated and rotated around the optical axis. E The external cavity mirror 15 is provided in the first housing 11, covering the light exit window 14 provided in the first housing 11. The external cavity mirror 15 may be provided inside the first housing 11, between the diffraction grating 13 and the light exit window 14. As described above, the first dew point meter 16 is disposed inside the first housing 11, and the first pipe 47 is connected to the air intake port 11A and the air exhaust port 11B of the first housing 11.

[0052] The installation positions of the first dew point meter 16, the air inlet 11A, and the air outlet 11B are not particularly limited to the example shown in Fig. 3, and may be changed as appropriate. Furthermore, the number of the air inlet 11A and the air outlet 11B and the number of the first pipes 47 connected thereto are also not particularly limited to the example shown in Fig. 3, and may be changed as appropriate. For example, the second laser light LB M The air inlet 11A may be arranged so that dry air is blown onto the permeable surface through which the air passes.

[0053] In addition to the above-mentioned components, the laser oscillator 10 includes a plurality of components, such as a first laser beam LB (described later). Ea mirror that directs the first laser beam LB E Although the optical system includes a collimator lens that collimates the expansion of the slow axis direction of the beam, for the sake of convenience, these components are not shown or described.

[0054] 4, the laser diode bar 12A is mainly made of a nitride semiconductor (GaN-based semiconductor) and has a plurality of emitters 12A3 arranged at intervals along one direction. Each of the plurality of emitters 12A3 emits a first laser light LB E Due to external resonance in the laser oscillator 10, each emitter 12A3 emits a first laser beam LB E The wavelengths of the first laser beam LB E The wavelength range is set to be 350 nm or more and 460 nm or less.

[0055] The front end faces of the laser diode bars 12A are covered with a first end face coating layer 12A1, and the rear end faces of the laser diode bars 12A are covered with a second end face coating layer 12A2. The first end face coating layer 12A1 is E and second laser light LB M The second end face coating layer 12A2 is adjusted to have a reflectance of less than 0.0% for light in the wavelength range of the first laser light LB. E and second laser light LB M When the emitter 12A3 oscillates as a laser, the first end face coating layer 12A1 emits a first laser beam LB E is emitted forward.

[0056] First laser light LB emitted from each of the plurality of emitters 12A3 E The beams travel toward the diffraction grating 13 after their spread in the fast axis direction and the slow axis direction is collimated and their rotation direction is changed.

[0057] The diffraction grating 13 reflects a plurality of first laser beams LB Eand emits the first laser beam LB E and directs the first laser beam LB to the external cavity mirror 15. In this embodiment, the diffraction grating 13 diffracts the first laser beam LB E The diffraction grating 13 transmits the first laser beam LB E It may be a type that reflects each of the above.

[0058] At this time, the diffraction grating 13 reflects the first laser beam LB E The plurality of first laser beams LB are irradiated so that their optical axes are close to each other and parallel to each other. E are diffracted, respectively.

[0059] The external cavity mirror 15 reflects the incident first laser beam LB E Each of the external cavity mirrors 15 transmits a portion of the light and reflects the remainder toward the diffraction grating 13. In this way, an external cavity is formed between the external cavity mirror 15 and each of the plurality of laser diode bars 12A, more specifically, each of the plurality of emitters 12A3.

[0060] The first laser light LB emitted from each emitter 12A3 of the laser diode bar 12A E The positional relationship between the laser diode bar 12A and the diffraction grating 13 is defined so that the optical axes of the laser diode bar 12A and the diffraction grating 13 overlap each other when they pass through the diffraction grating 13.

[0061] That is, the first laser light LB emitted from each of the plurality of emitters 12A3 provided in the plurality of laser diode bars 12A E are made to overlap with each other when they are incident on the external cavity mirror 15. By doing so, the plurality of first laser beams LB having different wavelengths are E The technique of superimposing and combining the first laser beams LB emitted from the plurality of emitters 12A3 provided in the plurality of laser diode bars 12A is called a wavelength beam combining technique (hereinafter, sometimes referred to as a WBC method). E is one second laser beam LB MThe laser beams are wavelength-multiplexed and emitted to the outside of the laser oscillator 10. As described above, the laser oscillator 10 shown in this embodiment is a WBC type external cavity semiconductor laser device.

[0062] [Findings that led to this disclosure] FIG. 5 is a cross-sectional photograph of the laser diode bar after the output of the second laser light has decreased below a predetermined value.

[0063] When the laser diode bar 12A is operated for a long time, the second laser light LB M When the laser diode bar 12A is physically analyzed, as shown in FIG. 5, the first laser beam LB E When the thickness of the first end face coating layer 12A1 changes significantly, the thickness of the first laser beam LB E The reflectance of the first end face coating layer 12A1 changes with respect to the incident light, and the above-mentioned conditions for configuring the external resonator are no longer met.

[0064] When the laser diode bar 12A is operated for a long time, the first laser light LB E It is known that a photochemical reaction occurs due to the decomposition of siloxane compounds contained in the atmosphere surrounding the emitter 12A3, resulting in the deposition of SiOx on the surface of the first facet coating layer 12A1. Therefore, the inventors of the present application investigated the relationship between the siloxane concentration in the atmosphere and the SiOx deposition rate, and investigated the upper limit of the siloxane concentration in the atmosphere. The results are shown in Figure 6.

[0065] Fig. 6 is a diagram showing the relationship between the siloxane concentration and the SiOx deposition rate. When the siloxane concentration is X and the SiOx deposition rate is Y, as is clear from Fig. 6, the relationship between X and Y is shown in formula (2).

[0066] Y=Ce x +D···(2) Here, C and D are constants.

[0067] The dashed line parallel to the horizontal axis (siloxane concentration) shown in FIG. 6 corresponds to the first acceptance standard in the performance test of the laser diode bar 12A.

[0068] Typically, the rated life of a semiconductor laser element is determined when the laser output drops by approximately 20%. In the laser diode bar 12A and emitter 12A3 shown in this embodiment, the product life ends when approximately 70 nm of SiOx deposits accumulate, and the laser diode bar 12A or laser oscillator 10 must be replaced.

[0069] Product life is extremely important for industrial equipment such as laser processing equipment, and a life of at least 5,000 hours is generally required, with 10,000 to 20,000 hours being the preferred life. In other words, for laser oscillator 10, it is necessary to create a siloxane concentration environment such that the amount of SiOx deposition after at least 5,000 hours is 70 nm or less, and preferably 10 nm or less.

[0070] In this embodiment, the first acceptable criterion is the first laser beam LB E This corresponds to the SiOx deposition rate when the thickness of the SiOx deposited on the surface of the first end face coating layer 12A1 becomes 70 nm when the test time for emitting the SiOx reaches 5000 hours. In this embodiment, the SiOx deposition rate corresponding to the first acceptable standard is 0.014 nm / min, and in the following description, this value may be referred to as the first threshold value.

[0071] Since the first tolerance criterion is the maximum allowable value for the SiOx deposition rate, in actual use the SiOx deposition rate must be reduced to a lower value, specifically, to the second tolerance criterion or below, which corresponds to the solid line parallel to the horizontal axis in Figure 6.

[0072] The second acceptance criterion is the first laser beam LB EThis corresponds to the SiOx deposition rate when the thickness of the SiOx deposited on the surface of the first end face coating layer 12A1 becomes 10 nm when the test time for emitting the SiOx reaches 5000 hours. In this embodiment, the SiOx deposition rate corresponding to the first tolerance criterion is 0.002 nm / min, and in the following description, this value may be referred to as the second threshold value.

[0073] Furthermore, as is clear from FIG. 6, in order to make the SiOx deposition rate equal to or less than the first allowable standard, the siloxane concentration in the atmosphere must be 0.7 μg / m 3 Furthermore, in order to keep the SiOx deposition rate below the second tolerance standard, the siloxane concentration in the atmosphere must be kept below 0.1 μg / m 3 I found that I needed to do the following:

[0074] Based on the above findings, it was thought that by controlling only the siloxane concentration in the space in which the laser diode bar 12A is housed, it would be possible to reduce the SiOx deposition rate and suppress deterioration in the reliability of the laser diode bar 12A, and ultimately the laser oscillator 10, during long-term use.

[0075] However, to achieve a siloxane concentration corresponding to an SiOx deposition rate that satisfies the second tolerance standard, it is necessary to use high-performance adsorbents for the first chemical filter 42 and the second chemical filter 52. In addition, it is necessary to improve the airflow discharge performance of the air pump 41, which makes the air pump 41 expensive.

[0076] One of the reasons for siloxane accumulation inside the first housing 11 is that siloxane is generated over time from components placed inside the first housing 11. Siloxane generation can be broadly divided into two patterns. The first pattern is when substances containing siloxane floating in the air adhere to the surfaces of the aforementioned components. In this case, the main components do not contain siloxane or molecules with a Si-O- skeleton similar to siloxane. Therefore, if the component surfaces are decontaminated and used, siloxane will not be generated inside the first housing 11. Cleaning with an organic solvent or baking in an oven is effective for removing siloxane adhering to the component surfaces. Because low-molecular-weight siloxanes have a high vapor pressure, most of the siloxane volatilizes when baked at a high temperature of 100°C or higher for a certain period of time. Therefore, it can be removed by, for example, blowing dry air inside the first housing 11.

[0077] The second cause of siloxanes is when the component contains siloxanes or molecules with a Si-O- skeleton similar to siloxanes in its main or secondary components. Silicone rubber O-rings, etc., whose main component is silicone with a Si-O- skeleton, may decompose over time and release low-molecular-weight siloxanes, so their use should be avoided. Fluorocarbon rubber O-rings do not contain silicone as their main component, but siloxanes are often contained in the mold release agent used during molding. Residual components of the mold release agent remaining in the micropores of the fluorocarbon rubber are known to cause siloxane generation. These residual components can also be removed by thorough cleaning and baking. Other resins should also be checked to determine whether they are siloxane-free, and consideration should be given to whether or not to use them in components and the pretreatment method.

[0078] Furthermore, care must be taken in the dry air circulation path, as siloxane components may remain inside parts such as flow rate adjustment valves such as first to fourth gas valves 46A, 46B, 46C, and 54, and flow meter 48. It is desirable to select an oil-free air pump 41, and to ensure that the parts that come into contact with the dry air are siloxane-free. As described above, in order to guarantee the life of laser oscillator (semiconductor laser device) 10, specifically to reduce the siloxane concentration inside first housing 11, it is necessary to manage the equipment and processes, including maintenance.

[0079] Furthermore, since it is difficult to measure the siloxane concentration while the laser oscillator 10 is in use and the measurement itself takes time, it is necessary to shorten the measurement cycle of the siloxane concentration to allow for a margin of error, but this increases the downtime of the laser oscillator 10 and, ultimately, the laser processing apparatus 400.

[0080] Based on the above, the inventors of the present invention have investigated various other factors that affect the SiOx deposition rate, and have found that the volumetric moisture content in the atmosphere affects the SiOx deposition rate.

[0081] Fig. 7 is a graph showing the continuous test time dependency of the laser light output fluctuation rate due to differences in the amount of moisture in the atmosphere containing a cyclic siloxane compound, and Fig. 8 is a graph showing the continuous test time dependency of the laser light output fluctuation rate due to differences in the amount of moisture in the atmosphere containing a linear siloxane compound.

[0082] In the example shown in FIG. 7, a laser diode (not shown) is placed in a sealed housing (not shown), and a first laser beam LB emitted from a light exit window (not shown) provided in the housing is E The output of the condenser was measured and its change over time was examined. In the example shown in Figure 7, a predetermined amount of cyclic siloxane was added to the atmosphere inside the enclosure. The dew point temperature inside the enclosure was about +1°C when there was no moisture content control, and about -9°C when the moisture content was controlled.

[0083] In the example shown in FIG. 8, the first laser light LB is irradiated in the same manner as in FIG. E The output of the first laser beam LB was measured and its change over time was investigated. However, in the example shown in Figure 8, linear siloxane was added to the atmosphere inside the housing, and different siloxane concentrations were prepared. In addition, for each of the different linear siloxane concentrations, the atmosphere inside the housing was prepared with and without water (water vapor) added. In the study shown in Figures 7 and 8, the first laser beam LB E The wavelength range of the first laser beam LB at the start of the test is the range mentioned above, that is, 350 nm or more and 460 nm or less. E The output P0 of the laser diode is operated, and the first laser beam LB is output after a predetermined time has elapsed. E is the ratio of the output P to the

[0084] As shown in Figure 7, when the amount of moisture in the atmosphere inside the housing was controlled, the laser light output fluctuation rate P / P0 was 95% or more even after five days of testing. On the other hand, when the amount of moisture in the atmosphere was not controlled, the laser light output fluctuation rate P / P0 had dropped to about 83% after five days of testing. In other words, whether or not the amount of moisture in the atmosphere was controlled made a difference in the fluctuation rate of the first laser light LB E The degree of output reduction was about two times greater.

[0085] Furthermore, as shown in Figure 8, when the siloxane concentration was low, after 70 hours of testing, the laser light output fluctuation rate P / P0 was about 92% without adding moisture, and about 88% with adding moisture. In other words, when the siloxane concentration was low, there was not much difference in the laser light output fluctuation rate P / P0 between the presence and absence of moisture, even after 70 hours of testing.

[0086] On the other hand, when the siloxane concentration was high, differences in the laser light output fluctuation rate P / P0 began to appear depending on whether moisture was added or not once the test time exceeded 7 hours. After 70 hours of test time, the laser light output fluctuation rate P / P0 was over 60% without moisture addition, but with moisture addition it had dropped significantly to around 30% to 40%.

[0087] In the examples shown in FIGS. 7 and 8, when the data showing a large drop in the laser light output fluctuation rate P / P0 is physically analyzed, it is found that the first laser light LB E It was confirmed that SiOx was deposited in the transparent portion of the first end face coating layer 12A1, and the film thickness of the first end face coating layer 12A1 was significantly increased.

[0088] As described above, the first laser light LB E Due to the photochemical reaction of the first laser beam LB, SiOx is deposited on the first facet coating layer 12A1 of the laser diode bar 12A, which reduces the product life of the laser diode bar 12A and, ultimately, the laser oscillator 10. To extend the product life of the laser diode bar 12A, it is necessary to reduce the SiOx deposition rate. E It has been thought that the power density and the siloxane concentration in the atmosphere of the space in which the laser diode bar 12A is placed have an effect, but the inventors' investigation has revealed that the volumetric moisture content in the atmosphere of the space also affects the SiOx deposition rate.

[0089] Taking this into consideration, we investigated the relationship between the volumetric water content and the SiOx deposition rate, and obtained the results shown in Figure 9. As shown in Figure 9, in this study, the siloxane concentration in the atmosphere was changed, and the relationship between the volumetric water content and the SiOx deposition rate was investigated for each case.

[0090] As is clear from Figure 9, even at the same siloxane concentration, the SiOx deposition rate tended to decrease as the volumetric water content decreased. 3In the following cases, it was found that the volumetric moisture content at which the SiOx deposition rate is equal to or less than the first threshold value is 3000 ppmv. In FIG. 9, the temperature in parentheses next to the number 3000 is the dew-point temperature when the volumetric moisture content is 3000 ppmv. In each of the following drawings, the dew-point temperature is also written next to the volumetric moisture content. In addition to the first and second threshold values, FIG. 9 also shows a dashed line indicating a third threshold value (=0.0005 nm / min). The second threshold value corresponds to a value at which the product life of the laser diode bar 12A is reliably 5000 hours or more. The third threshold value corresponds to a value at which the product life of the laser diode bar 12A is reliably 20000 hours or more. Note that 3000 ppmv corresponds to the design value of the volumetric moisture content shown in FIG. 2C. However, the design value can be changed as appropriate depending on the allowable range of the product life of the laser diode bar 12A. The volumetric water content at which the SiOx deposition rate is equal to or less than the second threshold or equal to the third threshold may be the design value shown in FIG. 2C.

[0091] The mechanism by which the amount of moisture in the atmosphere affects the SiOx deposition rate is currently under investigation, but the current hypothesis is that the following reaction occurs.

[0092] Fig. 10 is a schematic diagram showing a conventional speculation model for the reaction between a cyclic siloxane compound and moisture. Fig. 11 is a schematic diagram showing a new speculation model for the reaction between a cyclic siloxane compound and moisture, as well as between a linear siloxane compound and moisture.

[0093] As shown in FIG. 10, according to the conventional estimation model, the first laser beam LB E or second laser light LB MThis can cause some bonds in the cyclic siloxane compound to break or open, resulting in the formation of dangling bonds on the Si atoms. When moisture in the atmosphere is adsorbed onto these dangling bonds, an imbalance in the charge due to the OH groups can occur, which can bond with dangling bonds on other Si atoms to form siloxane groups (-O-Si-O-). As a result, contamination consisting of SiOx and carbon (C) is produced.

[0094] However, this model cannot adequately explain the phenomenon in which moisture increases the SiOx deposition rate in an atmosphere containing linear siloxane compounds.Furthermore, it was estimated that the moisture content dependence of the SiOx deposition rate would not be as large as previously described, even in an atmosphere containing cyclic siloxane compounds.

[0095] Therefore, the inventors of the present invention have proposed a model shown in FIG. E or second laser light LB M It was speculated that the photodecomposition reaction of water caused by the first laser beam LB contributed more to the increase in the SiOx deposition rate than the ring-opening of the bonds in the siloxane compound. E or second laser light LB M By this, water is photodecomposed into H3O + Radical and OH - These radicals and ions are generated. It is speculated that the SiOx yield, i.e., the SiOx deposition rate, increases when these radicals and ions react with siloxane compounds as strong oxidizing agents. According to this model, it is predicted that the moisture content dependence of the SiOx deposition rate does not depend significantly on whether the siloxane compound is linear or cyclic.

[0096] [Allowable ranges for volumetric moisture and siloxane] Figure 12 shows the allowable range of volumetric moisture. As shown in Figure 9, when the siloxane concentration is 0.7 μg / m 3 If the volumetric moisture content is 3000 ppmv or less, the SiOx deposition rate can be made equal to or less than the first threshold value.

[0097] However, as mentioned above, controlling the siloxane concentration is time-consuming. Therefore, we investigated the conditions under which the SiOx deposition rate can be kept below the first threshold, including the case where strict control of the siloxane concentration is not performed. Note that when the siloxane concentration shown in Figures 9 and 12 is 60 μg / m 3 This corresponds to a state in which the siloxane concentration in the atmosphere is higher than when a chemical filter for removing siloxane compounds is not used. Normally, the siloxane concentration is several μg / m 3 ~10-odd μg / m 3 That's about it.

[0098] As is clear from Figure 12, when the volumetric moisture content is 200 ppmv or less, in other words, when the dew point temperature is -39°C or less, the siloxane concentration in the atmosphere is 60 μg / m 3 In other words, even without strict concentration control of siloxane, the SiOx deposition rate could be kept below the first threshold, thereby ensuring the product life of the laser diode bar 12A.

[0099] 1 to 3, it is not necessary to keep the volumetric moisture content inside the first housing 11 at 200 ppmv or less at all times. It is sufficient that the volumetric moisture content inside the first housing 11 is kept at 200 ppmv or less at least when the laser diode bar 12A is in operation.

[0100] [Volumetric moisture content and siloxane concentration in each part of the laser processing equipment] Also, with regard to the second housing 21 and the third housing 31, it is preferable that the volumetric moisture content inside the first housing 11 is kept at 200 ppmv or less at least when the laser diode bar 12A is in operation.

[0101] Each housing included in the laser processing apparatus 400 must be airtight to prevent the inflow of dust, moisture, and the like. Furthermore, when other components are connected to the housing, the connections must be airtightly sealed. O-rings are often used to achieve airtight sealing. However, as mentioned above, commercially available O-rings often contain compounds containing molecules with an Si-O- skeleton, which are known to be a source of siloxane. For this reason, fluororubber O-rings are often selected, and the residual siloxane content in the O-rings is sufficiently reduced by appropriate cleaning, baking, and other procedures.

[0102] However, even in this case, a small amount of siloxane remains inside each housing. Furthermore, inside the second housing 21 and the third housing 31, the four second laser beams LB M As described above, the second laser beam LB passes through the processing laser beam LB. M is a plurality of first laser beams LB E That is, the optical components housed inside the second housing 21 and the third housing 31 receive the first laser light LB E The laser beam LB for processing, which has an output several tens to several hundreds times greater than the output of the laser beam LB, is irradiated.

[0103] Therefore, the siloxane remaining inside the second housing 21 and the third housing 31 is decomposed on the transmission surface of the processing laser light LB in the optical components inside the second housing 21 and the third housing 31, and SiOx accumulates on the transmission surface. The SiOx accumulation rate increases as the output of the processing laser light LB increases, so the thickness of the SiOx film accumulated on the transmission surface tends to increase.

[0104] In the first end face coating layer 12A1 of the laser diode bar 12A, the first laser light LB E Therefore, even if there is a slight change in the film thickness of the first end face coating layer 12A1 due to the deposition of SiOx, there is a risk that the external resonance condition will be lost due to the change in the reflectance of the first end face coating layer 12A1. E, and thus the second laser light LB M The output of the second laser beam LB M There is a risk that the beam quality may be degraded.

[0105] On the other hand, even if SiOx accumulates on the transmission surfaces of the processing laser light LB in the optical components inside the second housing 21 or the third housing 31, the deterioration in the output and beam quality of the processing laser light LB due to fluctuations in reflectivity is minimal. However, the second housing 21 and the third housing 31 have many connections with other components, and therefore use more O-rings for airtight sealing than the first housing 11. In other words, there is a possibility that SiOx with a thickness thicker than that of the SiOx deposited on the first end face coating layer 12A1 will be deposited on the transmission surfaces of the processing laser light LB. This SiOx contains many dangling bonds, which are dangling bonds, and also contains impurities such as carbon. The dangling bonds and impurities absorb the processing laser light LB, which may cause the SiOx to generate heat and raise the temperature of the optical components.

[0106] If the optical components are used for a long time with their temperature rising above a predetermined value, the optical components may be damaged. Furthermore, the refractive index of the optical components may change, causing the optical path of the processing laser beam LB to shift, resulting in losses inside the beam combiner 20 and the focusing optical unit 30. If this occurs, the output and beam quality of the processing laser beam LB may decrease. Therefore, it is necessary to control the volumetric moisture content and siloxane concentration in the atmosphere inside the second housing 21 and the third housing 31 as well.

[0107] For the same reason, it is preferable to control the volumetric moisture content and siloxane concentration in the atmosphere inside the sixth housing 110 (see FIG. 17) of the laser head 100 and the fifth housing 310 that partitions the processing chamber 300. In either case, the extent to which the volumetric moisture content and siloxane concentration in the atmosphere inside each housing are reduced is set appropriately depending on the volume of each housing, the output of the processing laser light LB, the heat dissipation properties of the optical components, etc.

[0108] The airflow circulation mechanism 40 also has connections that are similarly airtight sealed, but in many cases no O-rings are used. Furthermore, simple one-touch connectors are rarely used for these connections, and metal piping or metal members are often used to connect the components.

[0109] [Effects, etc.] As described above, the laser oscillator (semiconductor laser device) 10 according to this embodiment includes at least the laser module 12 having the laser diode bar (semiconductor laser element) 12A, and the first housing 11 that houses the laser module 12. Each of the plurality of emitters 12A3 provided in the laser diode bar 12A emits a first laser light LB E and emits the first laser beam LB E The wavelength range is 350 nm or more and 460 nm or less.

[0110] At least during operation of the laser diode bar 12A, the volumetric moisture content inside the first housing 11 is kept at 200 ppmv or less. Also, at least during operation of the laser diode bar 12A, the dew point temperature inside the first housing 11 is kept at -39°C or less.

[0111] According to this embodiment, the volumetric moisture content and the dew point temperature inside the first housing 11 are maintained within the aforementioned ranges, thereby suppressing the deposition rate of SiOx deposited on the surface of the first end face coating layer 12A1 of the laser diode bar 12A to below the first threshold value, thereby ensuring the product life of the laser diode bar 12A and ultimately the laser oscillator 10.

[0112] Furthermore, according to this embodiment, there is no need to strictly control the siloxane concentration inside the first housing 11; instead, the atmosphere inside the first housing 11 can be controlled based on the measurement results of the first dew point meter 16. Furthermore, there is no need to use high-performance adsorbents in the first chemical filter 42 and the second chemical filter 52, and the replacement cycles for these filters can be extended. This means that the number of steps required to control the siloxane concentration can be reduced, and the management and maintenance costs of the laser oscillator 10 and, ultimately, the laser processing apparatus 400 can be reduced.

[0113] The laser diode bar 12A has a plurality of emitters 12A3, each of which emits a first laser light LB E It is preferable that a plurality of laser modules 12 are housed inside the first housing 11. In this way, the laser diode bar 12A, and hence the second laser light LB emitted from the laser oscillator 10, M The output of the device can be increased.

[0114] The laser device 160 according to this embodiment includes at least one or more laser oscillators 10, a focusing optical unit 30, an airflow circulation mechanism 40, and a control unit 60. When the laser device 160 includes a plurality of laser oscillators 10, the laser device 160 may further include a beam combiner 20.

[0115] The airflow circulation mechanism 40 is connected to the first housing 11 and circulates an airflow, in this case dry air, inside the first housing 11.

[0116] The control unit 60 controls at least the operation of the airflow circulation mechanism 40. More specifically, the control unit 60 operates the airflow circulation mechanism 40 to control the volumetric moisture content inside the first housing 11. Specifically, the control unit 60 calculates the volumetric moisture content inside the first housing 11 based on the dew point temperatures measured by the first dew point meter 16 and the fourth dew point meter 44. Furthermore, the control unit 60 controls the operation of the air pump 41 based on the calculation result so that the volumetric moisture content inside the first housing 11 is maintained at 200 ppmv or less and the dew point temperature is maintained at -39°C or less.

[0117] According to this embodiment, by using the airflow circulation mechanism 40 to circulate dry air whose volumetric moisture content and dew point temperature are adjusted to fall within the aforementioned ranges inside the first housing 11, the deposition rate of SiOx deposited on the surface of the first end face coating layer 12A1 of the laser diode bar 12A can be suppressed to below the first threshold value, thereby ensuring the product life of the laser diode bar 12A and ultimately the laser oscillator 10.

[0118] Furthermore, by circulating dry air in the airflow path of the airflow circulation mechanism 40 including the first housing 11, the amount of dry air used when operating the laser device 160 can be reduced, and the operating costs of the laser device 160 can be reduced.

[0119] Furthermore, since the desiccant 43 is inserted in the airflow path, the volumetric moisture content and dew point temperature inside the first housing 11 can be easily reduced by circulating dry air through the airflow path with the air pump 41. Furthermore, the control unit 60 controls the amount and duration of dry air discharged by the air pump 41, thereby ensuring that the volumetric moisture content and dew point temperature inside the first housing 11 are within the aforementioned ranges.

[0120] The laser device 160 may be provided with a plurality of laser oscillators 10. In this case, an airflow circulation mechanism 40 is connected to each of the plurality of first housings 11. This increases the output of the processing laser light LB. Furthermore, the product life of the laser oscillators 10 having the laser diode bars 12A, and therefore the laser device 160, can be secured.

[0121] As described above, the airflow circulation mechanism 40 is also connected to the second housing 21 of the beam combiner 20 and the third housing 31 of the focusing optical unit 30. The control unit 60 operates the airflow circulation mechanism 40 to control the volumetric moisture content inside each of the second housing 21 and the third housing 31. Specifically, the control unit 60 calculates the volumetric moisture content inside each of the second housing 21 and the third housing 31 based on the dew point temperatures measured by the second to fourth dew point meters 22, 32, and 44. Furthermore, the control unit 60 controls the operation of the air pump 41 based on the calculation results so that the volumetric moisture content inside each of the second housing 21 and the third housing 31 is maintained at 200 ppmv or less and the dew point temperature is maintained at -39°C or less.

[0122] As described above, when the siloxane concentration and volumetric water content are high, SiOx accumulates on the transmitting surfaces of the optical components inside the second housing 21 and the third housing through which the processing laser light LB passes, and the SiOx absorbs the processing laser light LB, which may damage the optical components or change the refractive index of the optical components. In this case, repair or replacement of the beam combiner 20 or the focusing optical unit 30 may be necessary. Furthermore, the output of the processing laser light LB emitted from the focusing optical unit 30 may decrease, or the beam quality may deteriorate.

[0123] On the other hand, according to this embodiment, at least during operation of the laser diode bar 12A, the volumetric moisture content and dew point temperature can be controlled within the aforementioned ranges inside each of the second housing 21 and the third housing 31, so that the deposition rate of SiOx on the surfaces of the optical components can be suppressed, and the maintenance frequency of the beam combiner 20, the focusing optical unit 30, and ultimately the laser device 160 can be ensured.

[0124] The laser processing apparatus 400 according to this embodiment includes the above-mentioned laser device 160 and a laser beam LB Eand a laser head 100 connected to the optical fiber 90 and emitting the processing laser light LB received from the optical fiber 90.

[0125] By configuring the laser processing apparatus 400 in this manner, a high-power processing laser beam LB can be irradiated onto the workpiece W. For example, welding, cutting, and drilling of thick workpieces W can be performed at high speed. Furthermore, the deposition rate of SiOx deposited on the surface of the first end face coating layer 12A1 of the laser diode bar 12A can be reduced to below the first threshold, thereby ensuring the product life of the laser oscillator 10 having the laser diode bar 12A. This reduces the replacement frequency of the laser oscillator 10 in the laser processing apparatus 400 and, consequently, the running costs of the laser processing apparatus 400. Furthermore, in the laser processing apparatus 400, the internal volumetric moisture content and dew point temperature of the housing containing the optical components having the transmitting surfaces of the processing laser beam LB can be set within the aforementioned ranges. This reduces the deposition rate of SiOx on the transmitting surfaces of the optical components for the processing laser beam LB, thereby reducing the maintenance frequency of the beam combiner 20 and the focusing optical unit 30 and, consequently, the running costs of the laser processing apparatus 400. In addition, it is possible to suppress a decrease in the output and beam quality of the processing laser light LB irradiated onto the workpiece W, and to maintain high laser processing quality.

[0126] <Variation 1> Fig. 13 is a diagram showing the allowable range of volumetric moisture content according to Modification 1. For ease of explanation, in Fig. 13 and the following drawings, the same parts as those in Embodiment 1 are denoted by the same reference numerals, and detailed explanations thereof will be omitted.

[0127] 13, in order to reliably keep the deposition rate of SiOx deposited on the surface of the first facet coating layer 12A1 of the laser diode bar 12A below the first threshold, it is necessary to control not only the volumetric moisture content but also the siloxane concentration inside the first housing 11. Specifically, at least during operation of the laser diode bar 12A, it is necessary to control the volumetric moisture content inside the first housing 11 to be 3000 ppmv or less and the siloxane concentration to be 0.7 μg / m 3 It is preferable that the dew point temperature inside the first housing 11 is kept at -9°C or lower and the siloxane concentration is kept at 0.7 μg / m or lower at least during operation of the laser diode bar 12A. 3 It is preferable that the following is maintained:

[0128] By doing so, the deposition rate of SiOx deposited on the surface of the first facet coating layer 12A1 of the laser diode bar 12A can be reliably suppressed to below the first threshold value, thereby ensuring the product life of the laser diode bar 12A and, ultimately, the laser oscillator 10.

[0129] As mentioned above, the siloxane concentration inside the first housing 11 is usually 10 μg / m 3 In view of this, the siloxane concentration is 60 μg / m or less. 3 In such cases, the limitations on the volumetric moisture content and dew point temperature set forth in the first embodiment can be said to be excessive.

[0130] If the siloxane concentration is not strictly controlled, it is preferable that the volumetric moisture content inside the first housing 11 be maintained at 100 ppmv or more and 3000 ppmv or less at least during operation of the laser diode bar 12A. It is also preferable that the dew point temperature inside the first housing 11 be maintained at -46°C or more and -9°C or less at least during operation of the laser diode bar 12A.

[0131] Furthermore, it is more preferable that the volumetric moisture content inside the first housing 11 be maintained at 100 ppmv or more and 1000 ppmv or less at least during operation of the laser diode bar 12A.It is also more preferable that the dew point temperature inside the first housing 11 be maintained at -46°C or more and -23°C or less at least during operation of the laser diode bar 12A.

[0132] By doing so, the deposition rate of SiOx deposited on the surface of the first facet coating layer 12A1 of the laser diode bar 12A can be suppressed to the first threshold value or less, thereby ensuring the product life of the laser diode bar 12A and, ultimately, the laser oscillator 10.

[0133] <Variation 2> FIG. 14 is a diagram showing the allowable range of volumetric water content according to the second modification.

[0134] 14, in order to make the deposition rate of SiOx deposited on the surface of the first facet coating layer 12A1 of the laser diode bar 12A equal to or less than the second threshold, it is necessary to control, for example, both the volumetric moisture content and the siloxane concentration inside the first housing 11. Specifically, at least during operation of the laser diode bar 12A, it is necessary to control the volumetric moisture content inside the first housing 11 to be equal to or less than 3000 ppmv and the siloxane concentration to be equal to or less than 0.1 μg / m. 3 It is preferable that the dew point temperature inside the first housing 11 is kept at -9°C or lower and the siloxane concentration is kept at 0.1 μg / m or lower at least during operation of the laser diode bar 12A. 3 It is preferable that the following is maintained:

[0135] By doing so, the deposition rate of SiOx deposited on the surface of the first facet coating layer 12A1 of the laser diode bar 12A can be reliably suppressed to below the second threshold, and the product life of the laser diode bar 12A, and ultimately the laser oscillator 10, can be extended to 5,000 hours or more.

[0136] <Variation 3> FIG. 15 is a diagram showing the allowable range of volumetric water content according to the third modification.

[0137] 15, in order to keep the deposition rate of SiOx deposited on the surface of the first facet coating layer 12A1 of the laser diode bar 12A below the third threshold, it is necessary to control both the volumetric moisture content and the siloxane concentration inside the first housing 11. For example, at least during operation of the laser diode bar 12A, it is necessary to control the volumetric moisture content inside the first housing 11 to be 500 ppmv or less and the siloxane concentration to be 0.1 μg / m 3 It is preferable that the dew point temperature inside the first housing 11 is kept at -30°C or lower and the siloxane concentration is kept at 0.1 μg / m or lower at least during operation of the laser diode bar 12A. 3 It is preferable that the following is maintained:

[0138] By doing so, the deposition rate of SiOx deposited on the surface of the first facet coating layer 12A1 of the laser diode bar 12A can be reliably suppressed to below the third threshold, and the product life of the laser diode bar 12A, and ultimately the laser oscillator 10, can be extended to 20,000 hours or more.

[0139] <Variation 4> FIG. 16 is a diagram showing the allowable range of volumetric water content according to the fourth modification.

[0140] In order to make the deposition rate of SiOx deposited on the surface of the first facet coating layer 12A1 of the laser diode bar 12A equal to or lower than the third threshold, it is necessary to control both the volumetric moisture content and the siloxane concentration inside the first housing 11 within the ranges shown in Fig. 16. In other words, at least during operation of the laser diode bar 12A, it is necessary to control the volumetric moisture content inside the first housing 11 to be equal to or lower than 50 ppmv and the siloxane concentration to be equal to or lower than 0.7 µg / m 3 It is preferable that the dew point temperature inside the first housing 11 is kept at -52°C or lower and the siloxane concentration is kept at 0.7 μg / m or lower at least during operation of the laser diode bar 12A. 3 It is preferable that the following is maintained:

[0141] By doing so, the deposition rate of SiOx deposited on the surface of the first facet coating layer 12A1 of the laser diode bar 12A can be reliably suppressed to below the third threshold, and the product life of the laser diode bar 12A, and ultimately the laser oscillator 10, can be extended to 20,000 hours or more.

[0142] (Embodiment 2) FIG. 17 is a schematic diagram of the inside of the laser head according to the second embodiment.

[0143] The laser head 100 of this embodiment differs from the configuration shown in the first embodiment in that an airflow circulation mechanism 40 is connected.

[0144] 17, the laser head 100 accommodates a plurality of optical components in a mutually arranged relationship inside a sixth housing 110. In the example shown in FIG. 17, a collimation lens 120, a condenser lens 130, and a protective glass 140 are shown as the optical components, but the present invention is not limited to these, and other optical components may be accommodated inside the sixth housing 110.

[0145] The collimation lens 120 collimates the processing laser light LB that is guided by the optical fiber 90 connected to the sixth housing 110 and travels inside the sixth housing 110. The condenser lens 130 focuses the processing laser light LB that has been collimated by the collimation lens 120 toward the processing point of the workpiece W. The protective glass 140 transmits the processing laser light LB that has been focused by the condenser lens 130 and outputs it to the outside of the laser head 100. The protective glass 140 also prevents fumes and spatters that are generated during laser processing of the workpiece W from entering the inside of the sixth housing 110 and adhering to optical components. The protective glass 140 is usually made up of multiple glass plates.

[0146] Additionally, a sixth dew point meter 150 is disposed inside the sixth housing 110. The sixth dew point meter 150 measures the dew point temperature inside the sixth housing 110, and the control unit 60 calculates the volumetric moisture content inside the sixth housing 110 based on the dew point temperature measured by the sixth dew point meter 150. Based on the calculation result, the control unit 60 controls the operation of the airflow circulation mechanism 40 so that the volumetric moisture content inside the sixth housing 110 is equal to or less than a predetermined value, and so that the dew point temperature is equal to or less than another predetermined value.

[0147] 17, the first pipe 47 is connected to the sixth housing 110, and dry air is supplied from the air flow circulation mechanism 40 to the inside of the sixth housing 110 and then exhausted from the sixth housing 110. This dry air is adjusted by the air flow circulation mechanism 40 so that the volumetric moisture content, or both the volumetric moisture content and the siloxane concentration, are below a predetermined value.

[0148] According to this embodiment, the airflow circulation mechanism 40 is connected to the sixth housing 110, and the above-mentioned dry air is circulated by the airflow circulation mechanism 40 including the sixth housing 110. In this way, the deposition rate of SiOx on the transmission surface of the processing laser light LB in the optical components provided in the laser head 100 can be suppressed, and the maintenance frequency of the laser head 100 and, ultimately, the running costs of the laser processing apparatus 400 can be reduced. In addition, a decrease in the output and beam quality of the processing laser light LB irradiated onto the workpiece W can be suppressed, and high laser processing quality can be maintained.

[0149] 1, the laser oscillator 10, the beam combiner 20, and the focusing optical unit 30 of the laser device 160 are housed in a light source chamber 200 partitioned by a fourth housing 80. The laser head 100 and the workpiece W to be irradiated with the processing laser light LB are housed in a processing chamber 300 partitioned by a fifth housing 310. The fifth housing 310 is connected to an airflow circulation mechanism 40.

[0150] The control unit 60 operates the airflow circulation mechanism 40 to control the volumetric moisture content inside the fifth housing 310. Specifically, the control unit 60 calculates the volumetric moisture content inside the fifth housing 310 based on the dew point temperatures measured by the fourth and fifth dew point meters 44, 320, respectively. Furthermore, the control unit 60 controls the operation of the air pump 41 based on the calculation results so that the volumetric moisture content and the dew point temperature inside the fifth housing 310 are maintained at or below predetermined values. Similarly, the siloxane concentration is maintained at or below a predetermined value.

[0151] As described above, in the laser head 100, by connecting the airflow circulation mechanism 40, the volumetric moisture content or the volumetric moisture content and siloxane concentration of the atmosphere inside the sixth housing 110 is controlled to be at the same level as inside the second housing 21 and the third housing 31.

[0152] However, the sixth housing 110 is usually not structured to be completely airtight. In this case, if the volumetric moisture content and dew point temperature of the processing chamber 300 are not controlled, SiOx may be deposited on the optical components inside the sixth housing 110 due to photodecomposition of siloxane, which may reduce the output and beam quality of the processing laser light LB.

[0153] Furthermore, the processing laser beam LB passes through a protective glass 140 (see FIG. 17) provided at the light emission port of the laser head 100 and is emitted to the outside of the laser head 100. In this case, if the volumetric moisture content of the processing chamber 300, and the dew point temperature or both the volumetric moisture content and the siloxane concentration, are not controlled, SiOx may be deposited on the surface of the protective glass 140 facing the workpiece W due to photodecomposition of siloxane, which may reduce the output and beam quality of the processing laser beam LB.

[0154] By circulating dry air, which is generated by the airflow circulation mechanism 40 and in which the volumetric moisture content and silox concentration are controlled, inside the fifth housing 310, it is possible to suppress the deposition rate of SiOx on the transmission surface of the processing laser light LB in the optical components provided in the laser head 100. This reduces the maintenance frequency of the laser head 100 and, in turn, the running costs of the laser processing apparatus 400. In addition, it is possible to suppress a decrease in the output and beam quality of the processing laser light LB irradiated onto the workpiece W, thereby maintaining high laser processing quality.

[0155] The position of the first pipe 47 connected to the sixth housing 110 is not particularly limited to the example shown in Fig. 17. For example, the connection position of the first pipe 47 or its shape inside the sixth housing 110 may be changed so that the dry air supplied from the airflow circulation mechanism 40 is blown onto the transmitting surfaces of the collimation lens 120 and the condenser lens 130 through which the processing laser light LB passes.

[0156] In this way, dry air whose volumetric moisture content and dew point temperature or both volumetric moisture content and siloxane concentration are controlled is blown onto the transmitting surface of the processing laser beam LB in a predetermined optical component inside the sixth housing 110. This reliably suppresses the deposition rate of SiOx on the transmitting surface of the processing laser beam LB in the optical component, thereby reducing the maintenance frequency of the laser head 100 and, ultimately, the running costs of the laser processing apparatus 400. Furthermore, it is possible to suppress a decrease in the output and beam quality of the processing laser beam LB irradiated onto the workpiece W, thereby maintaining high laser processing quality.

[0157] It is preferable that the dry air supplied from the air circulation mechanism 40 be blown onto the transmitting surface of the processing laser light LB of the optical components arranged inside the beam combiner 20 and the focusing optical unit 30. For example, in the focusing optical unit 30, it is preferable that the dry air supplied from the air circulation mechanism 40 be blown onto the transmitting surface of the focusing lens housed inside the third housing 31 through which the processing laser light LB is transmitted.

[0158] In this way, dry air whose volumetric moisture content and dew point temperature or both volumetric moisture content and siloxane concentration are controlled is blown onto the transmitting surface of the processing laser beam LB in the optical component. This reliably suppresses the deposition rate of SiOx on the transmitting surface of the processing laser beam LB in the optical component, reducing the maintenance frequency of the laser head 100 and, ultimately, the running costs of the laser processing apparatus 400. Furthermore, it is possible to suppress a decrease in the output and beam quality of the processing laser beam LB irradiated onto the workpiece W, thereby maintaining high laser processing quality.

[0159] (Other embodiments) Although the present specification has shown an example in which the laser oscillator 10 is a WBC-type external cavity semiconductor laser device, the present invention is not limited to this. For example, only one or more laser diode bars 12A may be disposed inside the first housing 11. Alternatively, only one or more semiconductor laser elements may be disposed inside the first housing 11, and the semiconductor laser elements may have a single emitter. In this case, the first housing 11 is hermetically sealed except for the connection portion of the first pipe 47.

[0160] Furthermore, the airflow circulation mechanism 40 does not have to be connected to the first housing 11. It is sufficient that the volumetric moisture content and dew point temperature inside the first housing 11 are each below a predetermined value. It is also sufficient that the siloxane concentration inside the first housing 11 is below another predetermined value. Note that even in this case, the first housing 11 is hermetically sealed.

[0161] In the first embodiment, the first laser light LB EThe wavelength range of the laser beam is set to 350 nm or more and 460 nm or less, but is not limited to this range. As mentioned above, for cyclic siloxanes and linear siloxanes to deposit as inorganic SiOx, Si-C and Si-O bonds must be broken, i.e., the Si-O bond must dissociate, generating -Si-O- radicals. Figure 18 shows the calculated bond dissociation energies of various Si- and C-based bonds. Dissociating Si-O and Si-C bonds requires a large amount of energy, which is expected to require a wavelength of 400 nm or less. While this value is inconsistent with the actual occurrence of siloxane-derived SiOx deposition in blue lasers, it is known that under very high light density conditions, a two-photon absorption process occurs, in which the energy of two photons is absorbed at once. It is possible that this two-photon absorption process occurs during siloxane decomposition at the laser facet.

[0162] The model shown in FIG. 11, that is, the first laser beam LB E or second laser light LB M In light of this, the photodecomposition reaction of water caused by the first laser beam LB E When the wavelength range of the light emitted from the laser diode bar (semiconductor laser element) 12A is 550 nm or less, or more specifically, 350 nm or more and 550 nm or less, the volumetric moisture content inside the first housing 11, etc. is controlled to within the range described in the present specification. Alternatively, the siloxane concentration inside the first housing 11, etc. is controlled to within the range described in the present specification. Alternatively, both the volumetric moisture content and the siloxane concentration inside the first housing 11, etc. are controlled to within the range described in the present specification. By doing so, the deposition rate of deposits adhering to the first facet coating layer 12A1, which is the light-emitting facet of the laser diode bar (semiconductor laser element) 12A, can be suppressed, and degradation of operational reliability can be suppressed, which is useful.

[0163] The first laser light LB emitted from the emitter 12A3 of the laser diode bar 12A E When the output of the first laser beam LB is to be increased from several tens of mW to several hundreds of mW or even to about 1 W, EThe wavelength range of the first laser light LB is preferably from blue-violet to green. This is because the active layer (not shown) of the emitter 12A3 does not contain Al, and therefore the active layer can be formed stably. In other words, the first laser light LB E It is preferable that the wavelength range is 405 nm or more and 550 nm or less. [Industrial Applicability]

[0164] The semiconductor laser device of the present disclosure is useful because it can suppress the deposition rate of deposits adhering to the light-emitting end face of the semiconductor laser element and suppress deterioration in operational reliability. [Explanation of symbols]

[0165] 10 Laser oscillator (semiconductor laser device) 11 First cabinet 11A Air supply port 11B Exhaust port 12 Laser Module 12A Laser Diode Bar (Semiconductor Laser Element) 12A1 First end face coating layer 12A2 Second end face coating layer 12A3 emitter 13 Diffraction Grating 14 Light exit window 15 External cavity mirror 16 1st dew point meter 20 Beam combiner 21 Second cabinet 22 Second dew point meter 30 Condenser optical unit 31 Third cabinet 32 3rd dew point meter 40 Airflow circulation mechanism 41 Air Pump 42 First chemical filter 43 Desiccant 44 No. 4 dew point meter 45 Collection tube 46A First Gas Valve 46B Second gas valve 46C Third gas valve 47 First Pipe 48 Flow meter 49A Inlet 49B Outlet 50 Powered air supply mechanism 51 Dry air generation unit 52 Second chemical filter 53 Second piping 54 4th Gas Valve 60 Control Unit 61 Arithmetic section 62 Memory section 63 Display section 70 Power supply 80 4th cabinet 90 Optical Fiber 100 laser head 110 6th cabinet 120 Collimation Lens 130 Condenser Lens 140 Protective Glass 150 No. 6 dew point meter 160 Laser Device 200 Light source room 300 Processing room 310 5th cabinet 320 No. 5 dew point meter 400 Laser Processing Equipment LB E First laser beam LB M Second laser beam LB laser beam for processing double work

Claims

1. A semiconductor laser device comprising at least a semiconductor laser element and a first housing that houses the semiconductor laser element, the semiconductor laser element emits a first laser beam, the wavelength range of the first laser light is 550 nm or less, A semiconductor laser device, characterized in that the volumetric moisture content inside the first housing is kept at 200 ppmv or less at least when the semiconductor laser element is in operation.

2. 2. The semiconductor laser device according to claim 1, A semiconductor laser device, characterized in that the volumetric moisture content inside the first housing is kept at 50 ppmv or less at least during operation of the semiconductor laser element.

3. A semiconductor laser device comprising at least a semiconductor laser element and a first housing that houses the semiconductor laser element, the semiconductor laser element emits a first laser beam, the wavelength range of the first laser light is 550 nm or less, At least during operation of the semiconductor laser element, the volumetric moisture content inside the first housing is 3000 ppmv or less and the siloxane concentration is 0.7 μg / m ３ A semiconductor laser device characterized in that:

4. 4. The semiconductor laser device according to claim 3, At least during operation of the semiconductor laser element, the volumetric moisture content inside the first housing is 500 ppmv or less and the siloxane concentration is 0.1 μg / m ３ A semiconductor laser device characterized in that:

5. 2. The semiconductor laser device according to claim 1, the semiconductor laser element is a laser diode bar having multiple emitters; a first laser beam emitted from each of the plurality of emitters;

6. 2. The semiconductor laser device according to claim 1, A plurality of the semiconductor laser elements are housed inside the first housing, a first laser beam emitted from each of the plurality of semiconductor laser elements;

7. a semiconductor laser device according to any one of claims 1 to 6; an airflow circulation mechanism connected to the first housing and configured to circulate airflow inside the first housing; a control unit that controls the operation of at least the airflow circulation mechanism, The control unit operates the airflow circulation mechanism to control the volumetric moisture content inside the first housing, or to control both the volumetric moisture content and the siloxane concentration.

8. 8. The laser device according to claim 7, a plurality of the semiconductor laser devices are provided; A laser device, characterized in that the airflow circulation mechanism is connected to each of the plurality of first housings.

9. The laser device according to claim 7; an optical fiber connected to the laser device and guiding a processing laser beam including the first laser beam; a laser head connected to the optical fiber and configured to emit the processing laser light received from the optical fiber.

10. 10. The laser processing apparatus according to claim 9, the laser device further includes a focusing optical unit having at least a third housing and a focusing lens housed inside the first housing; the focusing optical unit optically couples the processing laser light to the optical fiber; the airflow circulation mechanism is connected to the third housing; A laser processing device characterized in that, at least when the semiconductor laser element is in operation, a gas in which the volumetric water content or both the volumetric water content and the siloxane concentration are controlled is blown from the air flow circulation mechanism onto the transmitting surface of the processing laser light in the focusing lens.

11. The laser processing apparatus according to claim 10, the laser head has a sixth housing and a plurality of optical components housed inside the sixth housing, the airflow circulation mechanism is connected to the sixth housing, A laser processing apparatus characterized in that, at least when the semiconductor laser element is in operation, a gas in which the volumetric water content or both the volumetric water content and the siloxane concentration are controlled is blown from the air flow circulation mechanism onto the transmitting surface of the processing laser light in at least one of the plurality of optical components.

12. 10. The laser processing apparatus according to claim 9, At least the semiconductor laser device is housed in a light source chamber partitioned by a fourth housing, The laser head and the workpiece to be irradiated with the processing laser light are accommodated in a processing chamber partitioned by a fifth housing, the airflow circulation mechanism is connected to at least the fifth housing; The control unit operates the airflow circulation mechanism to control the volumetric moisture content inside the fifth housing, or to control both the volumetric moisture content and the siloxane concentration.

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