JPH02285686A - Gas laser - Google Patents

Abstract

PURPOSE:To reduce a fluctuation in the output of a laser beam and to improve the quality of a laser processing by a method wherein a sound absorbing material is mounted on the inner wall of an external container covering a wind guiding part or the interior of the container is partitioned by a partition wall constituted of the sound absorbing material or an elastic material and moreover, the frequency of pressure pulsation is determined in such a way that the frequency is within a range of specified multiple of an acoustic resonance frequency inherent to these devices. CONSTITUTION:A frequency to beat a pressure pulsation is determined in such a way that the frequency is included within a range 0.8 to 1.2 times larger than a resonance frequency, which is determined according to the volume of a space 12a of a resonance container 10 excluding a porous sound absorbing material 11a in the container 10, the aperture area of a side hole 8, the length of a connecting duct 9 and the speed of sound of a gas laser medium. The container 10 absorbs the energy of a frequency component of pressure pulsation, which coincides with a resonance frequency determined by Helmholtz's resonance theorem, and the energy is made to dissipate by a friction loss in the hole 8 and at the connecting part 9. At this time, the residual amount which is short dissipation is absorbed by the material 11a adhered on the inner wall of the container. As a result, as the pressure pulsation is absorbed before being propagated to a laser resonator 1 and a periodical fluctuation in the pressure of a gas laser medium in the resonator 1 is eliminated, a discharge voltage is not fluctuated and the degree of variability of laser output is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a gas laser device such as a carbon dioxide laser, and particularly to a gas laser device that improves processing quality by reducing output fluctuations of laser light.

2. Description of the Related Art An example of the configuration of a gas laser device using a conventional roots blower is shown in FIG. The gas laser medium is supplied by the roots blower 3 through the laser resonator 10 supply duct 17, and is excited by discharge from the high voltage power supply 2 to output laser light. However, due to pressure pulsations in the gas laser medium generated by the roots blower 3, The discharge voltage changes. As a result, there is a problem in that the excitation input fluctuates, causing output fluctuations, resulting in increased cut surface roughness during cutting. Conventionally, an orifice (not shown in the figure) is provided in the supply duct 17 on the exit side of the Roots blower 3, or a large volume container is installed in series on the Roots blower exit side as described in Japanese Patent Application Laid-Open No. 63-7680. method is used.

Problems to be Solved by the Invention However, the orifice provided on the duct has the disadvantage of high blowing pressure loss of the gas laser medium, and when a container is provided in series with the duct, a sufficient container volume is required, making the device large. There was a problem to take shape.

The purpose of the present invention is to improve the quality of laser processing by eliminating pressure pulsations generated by a blower and reducing laser light output fluctuations without causing blowing pressure loss of the gas laser medium or increasing the size of the device. It's about doing.

Means for Solving the Problems In order to solve the above problems, the present invention provides a side hole in the gas laser medium supply side air guiding section of the laser resonator, and attaches a container to the side hole via a connecting section. Alternatively, the area of the air guide section including the side hole is covered with an external container having a cross-sectional area larger than the cross-sectional area of the air guide section. Then, attach sound-absorbing material to the inner wall of the container. Alternatively, the inside of the container may be partitioned with a partition made of a sound-absorbing material or an elastic material. In any of the above means,
The frequency of pressure fluctuation in the gas laser device is divided by the volume of the container excluding the sound absorbing material, the connection part, and the side hole or partition 7 ・-5
- The acoustic resonance frequency should be within the range of 0.8 to 1.2 times the acoustic resonance frequency that exists due to the combination of the volume of the space inside the container, the connection part, and the side hole.

Operation In the configuration of the present invention described above, pressure pulsations propagate as plane waves from the exit of the Roots blower toward the laser resonator within the air guide section that supplies the gaseous laser medium. If a side hole is made in the air guide section and a hollow container is connected or covered with an external container, pressure pulsations will enter the external container through the side hole. At this time, due to the Helmholtz resonance phenomenon, a sound wave near a resonance frequency determined by the volume of the container and the opening area of the connection opening or side hole is sucked into the container. The vibrational energy of the sucked pressure pulsations is lost due to friction loss when passing through the side holes. According to measurements made by the inventor, the proportion lost due to the friction loss is approximately 75%, and the remainder is discharged into the air guide section again.

Therefore, a sound-absorbing material is installed inside the container to absorb the vibrational energy of the pressure pulsations that remains without frictional loss. Alternatively, vibrations are transmitted to the space outside the bulkhead through the vibration of a bulkhead made of sound-absorbing or elastic materials,
The remaining vibrational energy of pressure pulsations that is not dissipated due to friction loss is absorbed. As a result, by absorbing pressure pulsations on the way to the laser resonator and preventing pressure pulsations from propagating to the laser resonator, fluctuations in the excitation input of the gas laser medium are suppressed, laser output fluctuations are reduced, and the quality of laser processing is improved. improve.

EXAMPLES Hereinafter, examples of the present invention will be explained with reference to the drawings. FIG. 1a shows the configuration of an embodiment of the invention. The laser resonator 1 excites a gas laser medium by discharge excitation by a high voltage power supply 2 and outputs laser light. The laser resonator 1 is connected by a supply duct 6 and an exhaust duct 7 to a gas cooler 4 attached to an air outlet 310 and a gas cooler 6 attached to an inlet 32 of each roots blower 3 . A side hole 8 is opened in the supply duct 6, and the resonance container 1o is connected to it through a connection duct 9. The length of each connecting duct 9 and the depth of the resonant vessel 10 are shorter than the pulsation wavelength so that no standing waves of pressure pulsations 9 .-7 are generated therein. A porous sound absorbing material 11i& is attached to the inner wall of the resonance container 10.

The volume of the resonance container 10 is the resonance frequency determined by the volume of the space 12 & excluding the porous sound absorbing material 11a in the resonance container 1Q, the opening area of the side hole 8, the length of the connection duct 9, and the sound speed of the gas laser medium. The frequency of pressure pulsation is determined to match the .

Next, the operation of the embodiment of the present invention will be explained. The pressure pulsations propagate from the air outlet 31 of the Roots blower 3 toward the laser resonator 10 through the supply duct 6 at a sonic speed determined by the composition of the gaseous laser medium. Since the propagation properties of the pressure pulsating waves in the supply duct 6 change at the side hole 8 , they propagate through the side hole 8 into the resonance vessel 10 . The resonance container 10 absorbs the frequency component energy of the pressure pulsation that matches the resonance frequency determined by the Helmholtz resonance principle, and the side hole 8 and the connecting portion 91? However, the remaining amount is absorbed by the porous sound absorbing material 11a.As a result, the pressure pulsations are absorbed before propagating to the laser resonator 10 and the gas inside the laser resonator 1 is absorbed. Since periodic fluctuations in the laser medium pressure are eliminated, the discharge voltage does not fluctuate, and the laser output fluctuation rate decreases. At this time, since the resonance container 1Q is parallel to the supply duct 6, no blowing pressure loss of the gas laser medium passing through the supply duct 6 occurs. Furthermore, since the upper limit of the dimensions of the resonance container 10 determined by the resonance conditions is determined by the wavelength of the pressure pulsation, the container can be added to the duct without increasing the size of the gas laser device.

Figures 1b and 1c show other embodiments of the present invention. 1st
Components with the same reference numerals as in Figure a have equivalent functions. In the example of FIG.
2b and space 13b. Volume of space 12b and side hole 8
The dimensions of the partition wall 14a are determined so that the frequency of the pressure pulsation matches the resonance frequency determined by the opening area of the connecting duct 9, the length of the connecting duct 9, and the sound speed of the gas laser medium. The remaining pulsating energy that has not been dissipated due to friction loss when being sucked into the resonance container 1o is absorbed by vibrating the gaseous laser medium in the space 13b through the partition wall 142L of the porous 11... Re-release from the container 10 is suppressed. In the example shown in FIG. 1C, a partition wall 14b made of an elastic material is provided to divide the resonance container 10 into a space 12C and a space 13C. The resonant frequency determined by the volume of the space 120, the opening area of the side hole 8, the length of the connecting duct 9, and the sound velocity of the gas laser medium, and the resonant frequency determined by the elastic modulus of the elastic partition wall 13C and the space 130 are determined by the resonant container 1. The pressure pulsations absorbed into the resonance container 10 are confined in the space 13C by adjusting the frequency of the pressure pulsations absorbed in the resonance chamber 10.

2A and 2A show still other embodiments in which the structure of the resonance container is changed, but the same reference numerals as in FIG. 1 have the same functions. In the example shown in FIG. 2a, the area of the supply duct 6 including the side hole 8 is covered with an external container 16. A porous sound absorbing material 11b is attached to the inner wall of the outer container 16. The volume of the outer container 16 is the volume of the space 12d excluding the porous sound absorbing material 11b in the outer container 16, and the side hole 8.
The frequency of the pressure pulsation is determined to match the resonance frequency determined by the aperture area of the gas laser medium and the sound velocity of the gas laser medium.

In the example of FIG. 2, the same reference numerals as in FIG. is divided into a space 126 and a space 13d. The positional dimensions of the partition wall 14C are determined so that the frequency of the pressure pulsation matches the resonance frequency determined by the volume of the space 126, the opening area of the side hole 8, and the sound speed of the gas laser medium. The remaining pulsating energy that has not been dissipated due to friction loss when being sucked into the outer container 15 is absorbed by vibrating the gas laser medium in the space 13d through the partition wall 14C made of porous sound absorbing material.
Re-release from the outer container 15 is suppressed. Also, although not shown, in the example of FIG. 2, as in the example of FIG. It may also be configured to confine the pressure pulsations that occur.

13.--Effects of the Invention As described above, in the gas laser device of the present invention, the pressure pulsations generated by the Roots blower are absorbed and removed before propagating to the laser resonator, so that the excitation conditions of the gas laser medium can be improved. The variation in the laser beam output direction due to the variation in is reduced, which has the effect of improving the quality of laser processing, and there is no blowing pressure loss of the gas laser medium, and there is no need to increase the size of the gas laser device.

[Brief explanation of drawings]

FIG. 1a is a gas laser medium circuit diagram of a gas laser device showing a first embodiment of the present invention, and FIGS. FIG. 2a is a cross-sectional view of a main part in the third embodiment, FIG. 2a is a gas laser medium circuit diagram of a gas laser device showing a fourth embodiment of the present invention, and FIG. FIG. 3 is a sectional view of a main part, and is a gas laser medium circuit diagram of a conventional gas laser device. 1...Laser resonator, 2...High voltage power supply, 3...Roots blower, 4...Gas cooler, 5...Old...Gas cooler , 6... Supply duct, 7... Exhaust duct, 8... Side hole, 9... Connection duct, 10... Resonance vessel , 11a, b... Porous sound absorbing material, 12aze
...Space inside the resonance container, 13b-d...
・Space separated by partition walls in the resonance container, 14a, c...
... Porous sound-absorbing material partition wall, 14b ... Elastic phase partition wall, 15 ... External container, 31 ... Roots blower air outlet, 32 ... Roots blower intake mouth.

Claims (12)

[Claims] (1) An excitation unit that excites a gas laser medium; a laser resonator that excites the gas laser medium and extracts laser light;
In a gas laser device comprising a blower for blowing a gas laser medium, a cooler for the gas laser medium, and an air guiding section that guides the gas laser medium from the blower to a laser resonator, 1. A gas laser device, characterized in that a side hole is provided in the supply-side air guide section, a container is attached to the side hole via a connecting section, and a sound absorbing material is attached to the inner wall of the container. (2) The frequency of pressure fluctuation within the gas laser device is included within the range of 0.8 to 1.2 times the acoustic resonance frequency formed by the internal volume of the container excluding the sound-absorbing material, the side hole, and the connection part. A gas laser device according to claim 1, characterized in that: (3) an excitation unit that excites a gas laser medium; a laser resonator that excites the gas laser medium and extracts laser light;
In a gas laser device comprising a blower for blowing a gas laser medium, a cooler for the gas laser medium, and an air guiding section that guides the gas laser medium from the blower to a laser resonator, A gas laser device characterized in that a side hole is provided in the supply side air guiding section, a container is attached to the side hole via a connecting section, and the inside of the container is partitioned by a partition wall. (4) Within the range of 0.8 to 1.2 times the acoustic resonance frequency of the volume of the space separated by the partition wall and containing the connection part in the container, the side hole, and the connection part, 4. The gas laser device according to claim 3, wherein the frequency of pressure fluctuation is included. (5) The gas laser device according to claim 3, wherein the partition wall is made of a sound absorbing material. (6) The gas laser device according to claim 3, wherein the partition wall is made of an elastic material. (7) an excitation unit that excites a gas laser medium; a laser resonator that excites the gas laser medium and extracts laser light;
In a gas laser device comprising a blower for blowing a gas laser medium, a cooler for the gas laser medium, and an air guiding section that guides the gas laser medium from the blower to a laser resonator, A side hole is provided in the supply side air guide part, the air guide part in a range including the side hole is covered by an outer container having a cross-sectional area larger than the cross-sectional area of the air guide part, and a sound absorbing material is attached to the inner wall of the outer container. A gas laser device characterized by: (8) The frequency of pressure fluctuation within the gas laser device is included within the range of 0.8 to 1.2 times the acoustic resonance frequency formed by the internal volume of the external container excluding the sound absorbing material and the side holes. A gas laser device according to claim 7 characterized by: (9) an excitation unit that excites a gas laser medium; a laser resonator that excites the gas laser medium and extracts laser light;
In a gas laser device comprising a blower for blowing a gas laser medium, a cooler for the gas laser medium, and an air guide section that guides the gas laser medium from the blower to a laser resonator, supplying the gas laser medium to the laser resonator. A side hole is provided in the side air guide part, the area of the air guide part including the side hole is covered by an external container having a cross-sectional area larger than the cross-sectional area of the air guide part, and the inside of the external container is separated by a partition wall. Characteristic gas laser device. (10) Pressure fluctuation within the gas laser device within a range of 0.8 to 1.2 times the acoustic resonance frequency formed by the volume of the space separated by the partition wall and containing the side hole in the external container and the side hole. 10. The gas laser device according to claim 9, wherein the gas laser device includes a frequency of . (11) The gas laser device according to claim 9, wherein the partition wall is made of a sound absorbing material. (12) The gas laser device according to claim 9, wherein the partition wall is made of an elastic material.