JP2015079783A - Gas laser oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems in that scattering light is emitted to a connecting part, which insulates and connects a mirror and the space of discharging means, with the result that temperature of this joining part increases, leading to a decrease in the insulation resistance of the insulation joining part, and shift of discharge to an insulation part.SOLUTION: In the present invention, in order to solve the foregoing problems, projections and recesses for scattering absorbing miscellaneous light are provided on the internal surface of a connecting part that insulates and connects a mirror and the space of discharging means. The shape of each of the recessed and projections is right-angle triangle. The length of the hypotenuse of each triangle is not less than four times but not greater than six times with respect to the wavelength of a laser beam. The inclination angle of the recesses and projections with respect to the direction of an optical axis is 10 to 25 degrees. The right angle part of each of the right-angle triangular projections and recesses of the non-discharge tube joining a partial reflector and a discharging part is oriented toward the partial reflector. The right-angle triangular projections and recesses of the discharge tube joining a total reflector and the discharging part are oriented toward the total reflector. The material of the joining part is glass or ceramic.

Description

  The present invention relates to a kW class axial flow type gas laser oscillation apparatus mainly used for sheet metal cutting.

  A conventional axial gas laser oscillation apparatus 900 will be described with reference to FIG.

  In this figure, reference numeral 901 denotes a discharge tube made of a dielectric, and reference numerals 902 and 903 denote electrodes provided around the discharge tube. Reference numeral 906 denotes a power source connected to the electrode. Reference numeral 907 denotes a discharge space in the discharge tube 901 sandwiched between the electrodes 902 and 903. Reference numeral 908 denotes a total reflection mirror, and reference numeral 909 denotes a partial reflection mirror. The total reflection mirror 908 and the partial reflection mirror 909 are fixedly disposed at both ends of the discharge space 907 to form an optical resonator.

  In addition, a high voltage of several tens of kV is applied to the normal electrode portion, and the total reflection mirror 908 and the partial reflection mirror 909 are insulated by providing a non-discharge tube 916 made of a dielectric between the electrodes. Reference numeral 910 denotes a laser beam output from the partial reflection mirror 909. Reference numeral 917 denotes an aperture for improving the quality of the laser beam.

  An arrow 911 indicates a laser gas flow and circulates in the gas laser oscillation device. 912 is a laser gas flow path, 913 and 914 are heat exchangers for lowering the temperature of the laser gas whose temperature has been increased by the discharge in the discharge space 907 and the operation of the blower, and 915 is a blower means for circulating the laser gas. A gas flow of about 100 m / sec is obtained in the discharge space 907 by the blowing means 915. The laser gas channel 912 and the discharge tube 901 are connected by a gas introduction unit 905.

  The above is the configuration of the conventional gas laser oscillation apparatus. Next, the operation thereof will be described.

  The laser gas sent out from the blower 915 passes through the laser gas flow path 912 and is introduced into the discharge tube 901 from the laser gas introduction unit 905. In this state, discharge is generated in the discharge space 907 from the electrodes 902 and 903 connected to the power source 906. The laser gas in the discharge space 907 is excited by obtaining this discharge energy, and the excited laser gas becomes a resonance state by an optical resonator formed by the final stage mirror 908 and the output mirror 909, and the laser beam 910 is output from the output mirror 909. Is output. This laser beam 910 is used for applications such as laser processing represented by cutting and welding.

JP 63-48879 A

  The problem of such a conventional laser oscillation apparatus will be described with reference to FIG.

  FIG. 10 shows a schematic configuration of an optical resonator portion in a conventional laser oscillation device.

  In this figure, reference numerals 901 to 917 are the same as the above-described technical background, and thus description thereof is omitted here. When laser oscillation is performed in order to obtain the laser beam 910, an optical resonance space 919 is formed between the total reflection mirror 908 and the partial reflection mirror 909 arranged with the required parallelism with respect to the optical axis 918. Due to the difference between the space 919 and the inner diameter of the aperture 917, there is a portion of the laser beam that is irradiated onto the aperture 917.

  Further, the total reflection mirror 908 and the partial reflection mirror 909 exist with the parallelism necessary for laser oscillation, but when this parallelism is significantly lost, it is compared with the case where the parallelism is maintained. As a result, the aperture 917 is more strongly irradiated with the laser beam. The laser beam is irradiated to the aperture 917, but the aperture 917 is made of a metal such as copper or aluminum, and most of the irradiated laser beam is reflected without being absorbed by the aperture, and is not necessary for optical resonance. The miscellaneous light 920 becomes.

  The miscellaneous light 920 is applied to a dischargeless tube 916 provided in the vicinity thereof. A part of the miscellaneous light 920 irradiated to the dischargeless tube is absorbed, a part is reflected, and a part is transmitted. The miscellaneous light 920 reflected here is absorbed, reflected, and transmitted again at another location in the dischargeless tube, and finally all the miscellaneous light 920 is absorbed. The temperature of the dischargeless tube 916 that has absorbed the miscellaneous light 920 rises depending on the amount of absorbed light.

  Further, the amount of light absorbed by one reflection depends on the incident angle at which the miscellaneous light 920 is irradiated to the dischargeless tube 916. This is shown in FIG. According to this figure, when the incident angle becomes 75 degrees or more, the absorptance increases rapidly, and becomes maximum when the incident angle is 90 degrees, that is, when the incident light is perpendicular to the dischargeless tube.

  Moreover, it turns out that it becomes a substantially constant absorption rate at 75 degrees or less. Therefore, in the dischargeless tube 916, the temperature tends to rise locally near the aperture where the incident angle of the miscellaneous light 920 increases.

  When the temperature of the dischargeless tube 916 rises in this way, the insulation resistance is reduced in the interior space of the dischargeless tube 916, and the discharge is easily discharged. Originally, an appropriate resonance state can be obtained by discharging in the discharge space 907. However, for the reasons described above, when the inside of the non-discharge tube 916 becomes high temperature and the discharge start voltage decreases, the discharge starts here. Had a problem of migrating.

  When the discharge is transferred, the temperature inside the dischargeless tube 916 rapidly increases, exceeds the heat resistance temperature of peripheral members such as the total reflection mirror 908 and the partial reflection mirror 909, and causes damage. Further, in order to prevent these damages, the control is performed to detect the state and automatically stop the supply of the high voltage from the power source 906 when the discharge is transferred into the dischargeless tube 916.

  In the gas laser oscillation device, in order to expand the uses such as sheet metal cutting and welding, the customer is required to increase the output. For this purpose, one of the effective means is to inject larger energy by increasing the voltage from the power supply 906 supplied to the discharge space 907.

  In that case, however, the voltage increases and the amount of miscellaneous light 920 reflected and generated by the aperture 917 increases due to an increase in output, so that the discharge transition into the non-discharge tube 916 is likely to occur. There were challenges.

  The present invention has been made in view of the above problems.

  In order to solve the above-mentioned problems, the present invention provides an uneven surface for dispersing and absorbing miscellaneous light on the inner surface of the connecting portion that insulates and couples the space between the mirror and the discharge means. It is a right triangle, the length of the hypotenuse is 4 times or more and 7 times or less with respect to the wavelength of the laser beam, the inclination angle of the unevenness with respect to the optical axis direction is 15 to 25 degrees, and the partial reflection mirror and the discharge part are joined. The right-angled triangular unevenness of the dischargeless tube points the right-angled part to the partial reflector side, and the rectangular triangle-shaped unevenness of the dischargeless tube that joins the total reflection mirror and the discharge part points the right-angled part to the total reflection mirror side. The bonding member is made of glass or ceramic.

  With the configuration shown in the present invention, it is possible to alleviate the temperature rise of the insulating junction and prevent discharge transition. Therefore, a high voltage can be applied to the discharge space to increase the injection energy, and a high-power laser beam can be obtained efficiently.

Schematic configuration diagram of an optical resonance part of a gas laser oscillation apparatus according to an embodiment of the present invention The enlarged view which shows the characteristic of the uneven | corrugated shape in embodiment of this invention The schematic diagram which shows the reflection direction in the uneven | corrugated | grooved part in embodiment of this invention Diagram showing the relationship between light absorption rate and incident angle The schematic diagram which shows the reflection direction in the uneven | corrugated | grooved part in embodiment of this invention Diagram showing the relationship between the reflection effect and the inclination angle of the hypotenuse of a right triangle Diagram showing the relationship between the scattering and reflection effects and the length of the uneven slope of a right triangle Configuration diagram of a gas laser processing machine using the gas laser oscillator of the present invention Configuration diagram of gas laser oscillation device according to prior art Schematic configuration diagram of optical resonator part of gas laser oscillation device according to prior art

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated, referring drawings.

(Embodiment)
FIG. 1 is a schematic configuration diagram of an optical resonator portion of a laser oscillation apparatus according to an embodiment of the present invention.

  In this figure, 101 is a discharge tube made of a dielectric material such as glass, and 102 and 103 are electrodes provided around the discharge tube. A power source 106 is connected to the electrode. Reference numeral 107 denotes a discharge space in the discharge tube 101 sandwiched between the electrodes 102 and 103.

  Reference numeral 108 denotes a total reflection mirror, and reference numeral 109 denotes a partial reflection mirror. The total reflection mirror 108 and the partial reflection mirror 109 are fixedly arranged at both ends of the discharge space 107 to form an optical resonator.

  Further, a high voltage of several tens of kV is applied to the normal electrode portion, and the total reflection mirror 108 and the partial reflection mirror 109 are insulated by providing a non-discharge tube 116 made of a dielectric between the electrodes. Reference numeral 110 denotes a laser beam output from the partial reflection mirror 109. Reference numeral 117 denotes an aperture for improving the quality of the laser beam.

  Right-sided triangular irregularities 121 are provided on the inner surface of the dischargeless tube 116 at the insulating junction. FIG. 2 shows an enlarged view of 116a and 116b of FIG.

  As shown in this figure, the shape of the unevenness is a right triangle, the length of the hypotenuse is 4 to 7 times the wavelength of the laser beam, and the inclination angle of the unevenness with respect to the optical axis direction is 15 to 15 times. The angle-less triangular irregularities on the inner surface of the dischargeless tube 116 that joins the partially reflecting mirror 109 and the electrode 103 are 25 degrees, and the discharge tube that joins the totally reflecting mirror 108 and the electrode 102 with the right angle portion facing the partially reflecting mirror side. The right-angled triangular irregularities on the inner surface of 116 are oriented with the right-angled part toward the total reflection mirror. The dischargeless tube 116 is made of glass having high heat resistance and low cost.

  As described above, due to the difference between the laser beam in the optical resonance space 119 and the inner diameter of the aperture 117, there is a portion of the laser beam that is irradiated to the aperture 117. The total reflection mirror 108 and the partial reflection mirror 109 have the parallelism necessary for laser oscillation. If this parallelism is significantly lost, it is compared with the case where the parallelism is maintained. As a result, the aperture 117 is more strongly irradiated with the laser beam.

  The laser beam is irradiated to the aperture 117. The aperture 117 is made of a metal such as copper or aluminum, and most of the irradiated laser beam is reflected without being absorbed by the aperture, and is not necessary for optical resonance. 120 miscellaneous light components are generated.

The miscellaneous light 120 is applied to the dischargeless tube 116 at an incident angle β as shown in FIG. At this time, if the inclination angle γ with respect to the optical axis of the right triangle and the hypotenuse is set to 15 degrees or more, the incident angle β is geometrically β = α−γ.

  Here, α represents the incident angle of miscellaneous light when the surface of the dischargeless tube 116 is straight and has a straight shape, and can take only a value in the range of 0 to 90 degrees. Therefore, even if α is the maximum value of 90 degrees, β does not become larger than 75 degrees.

  In addition, the light reflected by this surface is incident again at another place in the dischargeless tube at an incident angle of 75 degrees or less, and absorption, reflection, and transmission occur. Since the incident angle of the miscellaneous light 120 is always less than or equal to 75 degrees, it can be seen that the amount of light absorbed at each location is constant in a low-absorption region that is almost independent of the angle as shown in FIG. .

  Therefore, the temperature rise of the dischargeless tube 116 occurs uniformly as a whole.

  Further, the effect is reduced when the inclination angle is 25 degrees or more. This is shown in FIG. When the inclination angle is 25 degrees or more, as shown in FIG. 6, the component reflected by the inclined surface of the right triangle increases as the light reflected by the inclined surface increases, and is reflected by the inclined surface to another distant place. It is estimated that the effect (reflection effect) to be absorbed by is weakened.

  Further, the length of the inclined surface of the right triangle is most effective when the laser beam is 4 times or more and 7 times or less the wavelength. This is shown in FIG. If the slope is less than 4 times the wavelength of the laser light, the light wavelength is close to the slope length, so that a sufficient reflection effect cannot be obtained. It is presumed that the effect is reduced because the number of reflected components increases and the scattering effect due to unevenness is reduced.

  The material of the non-discharge tube is most effective when it is made of glass or ceramic that has high insulation and heat resistance, and can sufficiently absorb and reflect light.

  Next, FIG. 8 is a block diagram of the gas laser processing machine in the embodiment of the present invention. The laser beam 110 output from the gas laser oscillation apparatus 100 of the present invention is guided to the condensing lens 132 provided in the torch 131 by the reflecting mirror 130, and the laser beam 110 condensed by the condensing lens 131 is processed. Is used for applications such as cutting and welding.

  The processed workpiece 133 is mounted on a table 134, and the processed workpiece 133 is processed into an arbitrary shape by moving the condenser lens 132 by the X-axis motor 135 and the Y-axis motor 136. In FIG. 8, the condensing lens 132 is moved from the powers 135 and 136, but the same effect can be obtained by connecting the X-axis motor 135 and the Y-axis motor 136 to the table 134 side and moving them. .

  The gas laser oscillation device and the gas laser processing machine according to the present invention can reduce the temperature rise of the insulating junction and suppress the discharge transfer to the insulating portion while including an aperture for improving the quality of the laser beam. This is useful as a gas laser oscillation device and a gas laser processing machine capable of increasing the laser output.

DESCRIPTION OF SYMBOLS 101 Discharge tube 102 Electrode 103 Electrode 104 Orifice 105 Gas introduction part 106 Power supply 107 Discharge space 108 Total reflection mirror 109 Partial reflection mirror 110 Laser beam 111 Laser gas flow direction 112 Laser gas flow path 113 Heat exchanger 114 Heat exchanger 115 Blower 116 Nothing Discharge tube 117 Aperture 118 Optical axis 119 Optical resonance space 120 Miscellaneous light 121 Concavity and convexity 130 Reflection mirror 131 Torch 132 Condensing lens 133 Workpiece 134 Processing table 135 X-axis motor 135 Y-axis motor 901 Discharge tube 902 Electrode 903 Electrode 904 Orifice 905 Gas introduction 906 Power source 907 Discharge space 908 Total reflection mirror 909 Partial reflection mirror 910 Laser beam 911 Laser gas flow direction 912 Laser gas flow path 913 Heat exchanger 914 Exchanger 915 blower 916 No discharge tube 917 aperture 918 optical axis 919 optical resonance space 920 noisy light

Claims (7)

A discharge tube having a laser medium disposed therein, at least a pair of mirrors disposed on the optical axis of laser light emitted from the laser medium excited by the discharge tube, and an aperture disposed between the mirrors; A laser oscillation apparatus comprising a connection portion for insulating and coupling a space between a mirror and a discharge means, wherein an uneven surface for dispersing and absorbing miscellaneous light is formed on an inner surface of the connection portion. The gas laser oscillation device according to claim 1, wherein the uneven shape is a right triangle. The gas laser oscillation apparatus according to claim 1, wherein a length of a hypotenuse of the right triangle is set to be not less than 4 times and not more than 7 times a light wavelength of the laser. The gas laser oscillation device according to claim 1, wherein an inclination angle of a hypotenuse of the right triangle is 15 to 25 degrees with respect to an optical axis direction. The right triangle of the right-angled triangular shape is a discharge-free tube that joins the total reflection mirror and the discharge part with the right-angled part of the right-angled triangle facing the partial reflection mirror side. 2. The gas laser oscillation device according to claim 1, wherein said triangular triangular irregularities have a right angle portion directed toward the total reflection mirror. The gas laser oscillation apparatus according to claim 1, wherein the bonding member material having the irregularities is made of glass. The gas laser oscillation apparatus according to claim 1, wherein the joining member material having the irregularities is ceramic.

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