JP3132548B2 - Laser oscillator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser oscillator, and more particularly, to a laser oscillator having a preionization electrode.

[0002]

2. Description of the Related Art Conventionally, as a laser oscillator, for example, JP-A-6-291391 is known. In this device, both ends of a laser tube are supported by a support member, and two sets of main electrodes are provided in the axial direction in the tube. By the way, in a conventional laser oscillator including only such a main electrode, the discharge by the main electrode may not be performed smoothly at the start of driving. So, conventionally,
There has been proposed a laser oscillator in which a preionization electrode is provided in addition to the main electrode to perform preionization and then perform main discharge. As such a device, for example, one that performs preionization between a cathode of a main electrode and a ring as a preionization electrode has been proposed (for example, Japanese Patent Application Laid-Open No. 1-103-103).
889, JP-A-4-15974, JP-A-4-15974
No. 22178). Secondly, there has been proposed a device in which preionization is performed between a pin serving as a preionization electrode and an anode of a main electrode (for example, Japanese Patent Publication No. 6-10).
No. 5812). Thirdly, a method has been proposed in which preionization is performed between a ring serving as a preionization electrode and an anode of a main electrode (for example, Japanese Patent Publication No. 7-548).
No. 64).

[0003]

However, in the conventional apparatus provided with the above-mentioned preionization electrodes, one of the preionization electrodes is also used by the main electrode. Therefore, such a conventional apparatus has a disadvantage that when the outer diameter of the laser tube is increased, uniform preliminary ionization is not performed in the radial direction of the laser tube. Further, it has been pointed out that a high-voltage DC power supply serving as a power supply of the main electrode must be driven at a low output in advance before the main discharge is performed by the main electrode.

[0004]

In view of such circumstances, the present invention provides at least a pair of main electrodes provided in a laser tube, a DC power supply for applying a high voltage to the main electrodes, In the laser oscillator provided with gas supply means for supplying gas to and gas flowing in the laser tube, on the upstream side of the main electrode in the flow direction of the gas flowing in the laser tube,
A pair of ring-shaped electrodes for preliminary ionization are arranged, and
A preliminary ionization power source for applying a high-voltage pulse wave or an AC high voltage to the preliminary ionization electrode is provided.

[0005]

According to this structure, the preionization electrode is provided separately from the main electrode, and the preionization power supply is provided separately from the DC power supply for the main electrode. Therefore, regardless of the outer diameter of the laser tube, uniform preionization can be performed by the preionization electrode, and stable main discharge by the main electrode can be performed. In other words, even if the outer diameter of the laser tube increases,
Uniform preionization can be performed by the preionization electrode. Further, since the power supply for preliminary ionization is provided separately from the DC power supply for the main electrode, the DC power supply for the main electrode may be driven only when a laser beam having a required output is obtained.
In other words, there is no need to drive a high-voltage DC power supply serving as a power supply for the main electrode with a low output before performing the main discharge.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiment. In FIG. 1, a laser oscillator 1 has two laser tubes 2 having the same structure arranged vertically in the axial direction. Are supported by a manifold 3 as a common support member, and the other end of each laser tube 2 is supported by manifolds 4A and 4B as support members. The laser gas supply means 5 includes manifolds 4 at both ends.
The laser gas is supplied into each laser tube 2 via A and 4B, and the laser gas in each laser tube 2 is discharged from the central manifold 3 to the outside. It can be circulated and supplied into the laser tube 2. The laser gas supply means 5 includes, on the downstream side of the central manifold 3, a heat exchanger 6 for cooling the laser gas discharged from each of the laser tubes 2, and a blower 7 on the downstream side of the heat exchanger 6. The connection tubes 8 connect the manifold 3 and the heat exchanger 6 and the heat exchanger 6 and the blower 7, respectively. The blower 7 is capable of sending laser gas in two directions. One of the two branched laser gases from the blower 7 is a connecting tube 8A, a heat exchanger 9A for heating the laser gas, and the manifold 4
A is supplied to one laser tube 2 via A, and the other laser gas is supplied to the other laser tube 2 via a connection tube 8B, a heat exchanger 9B for heating the laser gas, and the manifold 4B. . By the way, each of the connection tubes 8, 8A, 8B is manufactured from a non-insulating material, and the shape of each of these connection tubes is cylindrical. Also, one manifold 4
B is provided with a reflection mirror 10 for reflecting the laser light excited in the laser tube 2, and the other manifold 4A reflects the laser light excited in the laser tube 2 and transmits the laser light. An output mirror 11 is provided. The reflection mirror 10 and the output mirror 11 are provided to face each other on the axis of the two laser tubes 2, and the laser light resonated by the pair of mirrors 10 and 11 is directed leftward from the output mirror 11. It can be radiated toward. However, each of the laser tubes 2 is provided with two pairs of main electrodes 12 and 13 facing each other in series, and one of the pair of main electrodes is used as a ground electrode 12 and the end of each laser tube 2 Part side, that is, the manifolds 3, 4
A, 4B side, respectively, and the other non-ground side electrode 13 is disposed at the center of each laser tube 2. At this time, the ground electrode 12 may be an anode and the non-ground electrode 13 may be a cathode, or conversely, the ground electrode 12 may be a cathode and the non-ground electrode 13 may be an anode. The pair of main electrodes 12 and 13 are connected via a wire 14 to a DC high-voltage circuit 15 as a power supply, and the pair of main electrodes 12 and 13 are connected to each other while a laser gas is circulated in the laser tube 2. By applying a high voltage to the laser beam, a discharge is generated between a pair of main electrodes to excite the laser gas. That is, the main discharge is performed. FIG. 2 is an enlarged cross-sectional view of the laser tube 2 on the left side of FIG. 1. The thickness of the laser tube 2 is the same in the entire region in the axial direction. The other portion is a small diameter portion 2b, and a continuous portion of the small diameter portion 2b and the large diameter portion 2a is connected by a tapered portion 2c. The ground-side electrode 12 is provided on the large-diameter portion 2a at both left and right ends of the laser tube 2, and the non-ground-side electrode 13 is provided on the large-diameter portion 2a at the center of the laser tube 2. Large diameter portion 2a of the laser tube 2
Has a protrusion 2d formed by protruding outward in the radial direction, and a rod-shaped ground electrode 12 or non-ground electrode 13 is radially penetrated in the center of each protrusion 2d and fixed with Kovar. are doing. The Kovar is provided for the purpose of absorbing the thermal expansion of each of the main electrodes 12 and 13 when the main electrodes 12 and 13 thermally expand. The projections 2d are provided, for example, at eight positions at equal intervals in the circumferential direction of the laser tube 2, and each of the projections 2d is provided with the ground electrode 12 or the non-ground electrode 13. That is, the ground-side electrode 12 or the non-ground-side electrode 13 is a set of eight in the circumferential direction. Each of the main electrodes 12 and 13 has an L-shaped distal end in the laser tube 2, and the L-shaped distal ends of the pair of main electrodes 12 and 13 face each other in the axial direction. At this time, the distal ends of the main electrodes 12 and 13 are located slightly radially outward from the inner peripheral surface of the small diameter portion 2b of the laser tube 2. Further, of the two pairs of main electrodes, the distance L1 between the pair of main electrodes 12 and 13 on the upstream side (left side) in the flow direction of the laser gas is changed to the distance between the pair of main electrodes 12 and 13 on the downstream side. It is set shorter than L2. Thus, the laser output can be increased. In addition, the laser tube 2
When the inside diameter of the small diameter portion 2b is A and the inside diameter of the large diameter portion 2a is B, if the ratio B / A between the small diameter portion 2b and the large diameter portion 2a is about 1.2, the inclination of the tapered portion 2c is increased. Is too slow, the laser gas flowing from the left side flows along the inner peripheral surface of the laser tube 2, and the main discharge is not performed well. Therefore, the large diameter portion 2a and the small diameter portion 2b
The ratio B / A is set to 1.6 or more to generate a sufficient turbulent flow in the tapered portion 2c so that a uniform main discharge can be performed in the laser tube 2. Further, in the present embodiment, a pair of ring-shaped preionization electrodes 2 is provided on the outer peripheral portion of the laser tube 2 upstream of the most upstream main electrode 12 in the laser gas flow direction.
1 is provided. As shown in FIG. 3 in an enlarged manner, the preionization electrode 21 is formed of a copper thin plate. The pair of preionization electrodes 21 is spaced apart from each other by a distance L in the entire circumferential direction of the laser tube 2.
3, that is, the two pre-ionization electrodes 21 are attached to the outer peripheral surface of the laser tube 2 such that the distance between the two pre-ionization electrodes 21 in the axial direction of the laser tube 2 is equal. The two preionization electrodes 21 are connected to a dedicated high-voltage AC power supply 22. Immediately before the main discharge by the main electrodes 12 and 13 is performed, an AC voltage of 3000 V is applied from the AC power supply 22 of the preionization electrode 21 to both the preionization electrodes 21. As a result, preionization occurs in the laser tube 2 at the position where the two preionization electrodes 21 are provided. By doing so, the subsequent main discharge is performed smoothly. The laser tube on the right side in FIG. 1 has the same structure as the laser tube on the left side described above with reference to the direction in which the laser gas flows, and a description thereof will be omitted. According to the configuration of the present embodiment described above, the main electrodes at positions close to the manifolds 3, 4 </ b> A, and 4 </ b> B as support members for the laser tubes 2 are all ground-side electrodes 12. Even if the distance between the ground-side electrode 12 and the ground-side electrode 12 is reduced by setting the ground-side electrodes 4A and 4B to the ground side, there is no possibility that leakage occurs between the ground-side electrode 12 and the manifolds 3, 4A, and 4B. For the same reason, the manifold 3 on the ground side
4A, the heat exchanger 6, which is on the ground side in proximity to 4B,
Since the blowers 7A and 9B and the blower 7 can be provided, the laser oscillator 1 can be manufactured in a small size. Also, even if spatter adheres to the inside of the connection tubes 8, 8A, 8B, no leak occurs because all the constituent members are grounds. Further, in this embodiment,
The pair of ring-shaped preionization electrodes 21 is connected to the main electrode 1.
2 and 13 and the preionizing electrode 2
1 is provided with a dedicated AC power supply 22. Therefore, regardless of the diameter of the laser tube 2, uniform preliminary ionization can be generated in the laser tube 2. Thereby, the main discharge by the main electrodes 12 and 13 can also be performed stably and smoothly. In addition, since the pair of preionization electrodes 21 are separated at the same distance in the entire circumferential direction, uniform preionization can be generated in the entire circumferential direction. (Second Embodiment) FIGS. 4 and 5 show a second embodiment of the present invention.
It shows an example. In the second embodiment, the preliminary ionization electrode 121 is formed of a copper wire having a circular cross section. In the second embodiment, the laser tube 102
Are formed on the outer peripheral surface thereof a pair of annular grooves 102e spaced apart from each other by a predetermined dimension in the axial direction.
A preliminary ionization electrode 121 made of the above-mentioned copper wire is disposed therein. In the second embodiment, since the above-described annular groove 102e is formed on the outer peripheral surface of the laser tube 102, the laser tube 102
An annular protrusion 102e 'is formed on the inner peripheral surface of the. Even in the second embodiment having such a configuration, the same operation and effect as those of the first embodiment can be obtained. (Third Embodiment) Next, FIG. 6 shows a third embodiment of the present invention. Laser tube 202 of the third embodiment
The laser tube 102 of the second embodiment has a smooth inner peripheral surface by omitting the annular projection 102e '. The other configuration is the same as that of the second embodiment, and even with the configuration of the third embodiment, the same operation and effect as those of the second embodiment can be obtained. In addition,
In each of the above embodiments, a power source for the preionization electrode 21 is:
Although the high-voltage AC power supply 22 is used, a power supply that generates a high-voltage pulse wave is used instead of the AC power supply 22, and the high-voltage pulse wave is applied to the preliminary ionization electrode 21 from the power supply. good.

[0007]

As described above, according to the present invention, uniform pre-ionization can be performed by the pre-ionization electrode, so that a stable main discharge can be performed by the main electrode. Can be

[Brief description of the drawings]

FIG. 1 is a layout diagram showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a laser tube 2 on the left side of FIG.

FIG. 3 is an enlarged sectional view of a main part of FIG. 2;

FIG. 4 is a sectional view of a main part showing another embodiment of the present invention.

FIG. 5 is an enlarged view of a main part of FIG. 5;

FIG. 6 is a sectional view of a main part showing another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laser oscillator 2 ... Laser tube 5 ... Laser gas supply means 12, 13 ... Main electrode 15 ... DC high voltage circuit (DC power supply) 21 ... Preliminary ionization electrode 22 ... AC power supply (power supply for preliminary ionization)

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-6-90042 (JP, A) JP-A-5-251794 (JP, A) JP-A-3-2277582 (JP, A) JP-A-1- 103889 (JP, A) Shokai Sho 61-192466 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01S 3/03-3/038 H01S 3/097-3/0979

Claims (3)

(57) [Claims] At least one pair of main electrodes provided in a laser tube, a DC power supply for applying a high voltage to the main electrode, a gas supplied to the laser tube, and a gas flow in the laser tube. In a laser oscillator provided with gas supply means, a pair of ring-shaped preionization electrodes is disposed on the upstream side of the main electrode in the flow direction of the gas flowing in the laser tube, A laser oscillator comprising a preionization power supply for applying a high-voltage pulse wave or an alternating high voltage to a preionization electrode. 2. The laser according to claim 1, wherein the pair of preionization electrodes are provided on an outer peripheral surface of the laser tube while maintaining a predetermined interval in an axial direction of the laser tube. Oscillator. 3. The laser device according to claim 1, wherein the pair of preionization electrodes are provided in a pair of annular grooves formed on an outer peripheral portion of the laser tube so as to be axially separated from each other. 3. The laser oscillator according to claim 1.