JP4193129B2 - Pulse gas laser oscillator - Google Patents

Description

  The present invention relates to a pulse gas laser oscillator, and more particularly to improvement of a main discharge electrode of a pulse gas laser oscillator.

Conventionally, as a pulse gas laser oscillator, a laser container filled with a laser gas, a main discharge electrode disposed facing the inside of the laser container, and a DC high-voltage pulse power source that discharges by applying a voltage between the main discharge electrodes And a laser gas is excited by causing a discharge between main discharge electrodes by the DC high-voltage pulse power source to cause laser oscillation (Patent Document 1, Patent Document 2).
Japanese Patent No. 2924942 JP-A 64-24479

Conventionally, in a pulse gas laser oscillator, a kamaboko type main discharge electrode is used as the main discharge electrode. However, it is difficult to increase the average output with such a main discharge electrode. For example, a TEA type CO ₂ laser oscillator suitable for laser marking or the like is capable of short pulse high peak oscillation, but cannot achieve high average output, and is unsuitable for cutting.
In order to increase the average output in the TEA type CO ₂ laser oscillator, the repetition frequency of about several tens Hz may be increased to, for example, about several KHz. However, when the repetition frequency is increased, the main discharge easily shifts from glow discharge to arc discharge. In particular, the TEA-type CO ₂ laser oscillator uses the atmospheric pressure of the laser gas to increase the output. However, the higher the pressure of the laser gas, the more likely it is that arc discharge occurs, and when arc discharge occurs, the maintenance interval due to damage to the electrode surface portion is short. There was a problem of becoming.
In view of such circumstances, the present invention provides a pulse gas laser oscillator capable of increasing the average output by suppressing the occurrence of arc discharge and achieving maintenance-free.

That is, the present invention comprises a laser container filled with a laser gas, a main discharge electrode disposed facing the inside of the laser container, and a direct-current high-voltage pulse power source that discharges by applying a voltage between the main discharge electrodes. In a pulsed gas laser oscillator that excites a laser gas by causing a discharge between main discharge electrodes by the DC high-voltage pulse power source to oscillate the laser,
The main discharge electrodes, is characterized in that it respectively to a coil-shaped electrode of the multiple, and was disposed to each other not face to the tip of the coiled electrode.

  According to the above configuration, since the coiled electrode becomes an impedance with respect to the pulse current, an excessive current does not flow to the specific electrode, and the discharge spreads from the tip of the electrode toward the root. Therefore, current density is reduced without current concentration. As a result, arc discharge is suppressed, so that it is easy to increase the average output, and it is possible to prevent the electrode surface portion from being damaged by arc discharge and to be maintenance-free.

The present invention will be described below with reference to the illustrated embodiment. In FIG. 1, two base plates 2 and 3 are arranged in parallel vertically in a cylindrical laser container 1 constituting a TEA type CO ₂ laser oscillator. Main discharge electrodes 4 and 5 are provided to face the base plates 2 and 3, respectively.
The base plates 2 and 3 are each made of a conductive material, and the main discharge electrodes 4 and 5 provided on the base plates 2 and 3 are each made of a member-like insulating material that is erected and fixed to the base plates 2 and 3. A plurality of support members 4a and 5a and a plurality of coiled electrodes 4b and 5b formed by winding around each of the support members 4a and 5a are provided. The support members 4a and 5a serve to fix the coiled electrodes 4b and 5b so as not to stagger, and may have any shape.

The support members 4a provided on the upper base plate 2 and the support members 5a provided on the lower base plate 3 are arranged so as to face each other, and thereby the plurality of windings wound around the support members. Coiled electrodes 4b and 5b are arranged to face each other across the discharge space.
Each of the coiled electrodes 4b and 5b is manufactured from a conductive material such as copper or stainless steel, and the base portions of the coiled portions are electrically connected to the base plate 2 or 3 so that the coiled portions are not in close contact with each other. It is. Such coiled electrodes 4b and 5b become a resistance to a current change rate (di / dt).

Prior to the main discharge between the main discharge electrodes 4 and 5, the lower base plate 3 has a preionization electrode for preionization with each coiled electrode 5 b constituting the main discharge electrode 5. 6 is provided. Of the coiled electrodes 4b and 5b arranged to face each other, the preliminary ionization electrode 6 is disposed on the lower coiled electrode 5b side serving as the ground side, and on the base side away from the front end portions facing each other. Each is attached via an insulating member 7.
The insulating member 7 is formed in a sleeve shape, and is fixed to the base plate 3 so as to surround the base portion of each coiled electrode 5b. The preliminary ionization electrode 6 is formed in a ring shape, and is attached to the outer peripheral portion of each insulating member 7 while being insulated from each coiled electrode 5 b and the base plate 3.

Outside the laser container 1, a DC high-voltage pulse power source 11 that discharges by applying a voltage between the main discharge electrodes 4 and 5 and a DC high-voltage pulse power source for trigger that pre-ionizes by applying a voltage to the pre-ionization electrode 6 12 are provided. Thus, the whole circuit configuration can be simplified by using the DC high voltage pulse power source 12 for trigger as a power source different from the DC high voltage pulse power source 11.
These power supplies 11 and 12 generate a trigger voltage by the power supply 12 after a predetermined time delay from the end of charging of the power supply 11 by master-slave synchronous control using the DC high-voltage pulse power supply 11 as a master and the triggering DC high-voltage pulse power supply 12 as a slave. You can make it.
The laser container 1 is composed of an outer metallic cylindrical member 1a and an inner metallic cylindrical member 1b, and a double cylindrical main capacitor is formed by enclosing a dielectric 13 therein. ing. An outer metal cylindrical member 1a is connected to the ground side common to the power sources 11 and 12, and a lower base plate 3 attached to the inner metal cylindrical member 1b via an insulating member (not shown) The inner metal cylindrical member 1b and the dielectric 13 are connected to the outer metal cylindrical member 1a via the wiring 14 penetrating therethrough, and therefore to the ground side.

On the other hand, the inner metallic cylindrical member 1b is connected to the upper base plate 2 via the wiring 15, and the inner metallic cylindrical member 1b is connected to the dielectric 13 and the outer metallic cylindrical member 1a. It is connected to the DC high-voltage pulse power supply 11 through a wiring 16 provided so as to penetrate therethrough.
Further, each of the preliminary ionization electrodes 6 is connected to the trigger DC high voltage pulse power supply 12 through a wiring 17 provided through the inner metal cylindrical member 1b, the dielectric 13 and the outer metal cylindrical member 1a. It is.

The base plates 2 and 3 are formed in a rectangular shape as shown in FIG. 2. In this embodiment, the support members 4a and 5a are arranged in three rows at regular intervals in the longitudinal direction of the base plates 2 and 3. The arrangement is fixed. And the arrangement positions in the longitudinal direction of the support members 4a and 5a in the first row and the third row are respectively set to be the same, and the arrangement positions in the longitudinal direction of the support members 4a and 5a in the center second row are The positions of the support members 4a and 5a in the first row and the third row are set at the middle position in the longitudinal direction.
The output mirror 21 and the first bend mirror 22 are arranged at both ends of the first row (the upper row in FIG. 2), and the second bend mirror 23 and the rear mirror are arranged at both ends of the third row. 24.

As a result, the laser can resonate between the output mirror 21 and the rear mirror 24 via the first bend mirror 22 and the second bend mirror 23. At this time, between the output mirror 21 and the first bend mirror 22, the laser passes between the coiled electrodes 4b and 5b in the first row arranged on a straight line on the straight line, and the second Also between the bend mirror 23 and the rear mirror 24, it passes between the coiled electrodes 4b and 5b in the third row arranged on a straight line on the straight line. And between the 1st bend mirror 22 and the 2nd bend mirror 23, a laser passes diagonally between each coil-like electrode 4b and 5b of the 3rd row.
The first bend mirror 22, the second bend mirror 23, and the rear mirror 24 are provided in the laser container 1, and the output mirror 21 seals the laser container 1, but the laser is transmitted from the output mirror 21 to the laser container. 1 can be emitted to the outside.

Next, as shown in FIG. 1, the laser container 1 is filled with a laser gas in which carbon dioxide, nitrogen, helium, and carbon monoxide are mixed at a predetermined composition ratio, and the laser gas is circulated in the laser container 1. Blowing means 25 is provided.
The blower means 25 is provided below the two circulation fans 26 disposed on both sides of the lower positions of the base plates 2 and 3, and is provided below each circulation fan 26, and is sent downward through the discharge space by the circulation fans 26. A fan guide 27 for guiding the laser gas directed upward from both inner surfaces of the metal cylindrical member 1b, and a heat exchanger 28 disposed between the two circulation fans 26 for cooling the laser gas that has passed through the discharge space, It has.
As shown in FIGS. 1 and 2, each of the base plates 2 and 3 is provided with through holes 4c and 5c adjacent to the support members 4a and 5a and the coiled electrodes 4b and 5b at intermediate positions thereof. The laser gas that has flown upward from the inner surfaces on both sides of the metal cylindrical member 1b circulates through the through holes 4c and 5c, and is formed between the coiled electrodes 4b and 5b. It can be made to circulate in the axial direction (the axial direction of the support members 4a and 5a).

In the above configuration, when the double cylindrical main capacitor constituted by the laser container 1 is charged by the DC high voltage pulse power source 11, the DC high voltage is supplied to each preliminary ionization electrode 6 by the DC high voltage pulse power source 12 for trigger. To be applied. Thus, preliminary ionization is performed between each preliminary ionization electrode 6 and each grounded coiled electrode 5b adjacent thereto.
Since the preionization is performed between the preionization electrodes 6 and the coiled electrodes 5b, the preionization is performed uniformly over the entire discharge space. Main discharge occurs between 4b and 5b.
As a result, the laser gas in the laser container 1 is excited, the laser is resonated between the output mirror 21 and the rear mirror 24, and the laser is emitted from the output mirror 21 to the outside.

At this time, since the coiled electrodes 4b and 5b each act as an impedance with respect to the pulse current, an excessive current does not flow through the specific coiled electrodes 4b and 5b. Further, since the discharge spreads from the tip of each coiled electrode 4b, 5b toward the base side, the current does not concentrate on one point of each coiled electrode 4b, 5b, and a stable glow discharge having a spread. It becomes.
As a result, since arc discharge is suppressed, damage to the electrode surface due to arc discharge can be prevented and maintenance-free can be achieved.
In addition, since the laser container 1 is a double-cylindrical main capacitor, the discharge loop length can be shortened, the rise and fall of the voltage applied between the discharge electrodes can be accelerated, and arc discharge can be suppressed and repeated at a high rate. Can be achieved.

Furthermore, since the laser gas flows through the through holes 4c and 5c and flows in the axial direction of the coiled electrode from between the coiled electrodes 4b and 5b, the clearance ratio of the laser gas in the discharge space must be kept high. This also makes it possible to suppress arc discharge and increase repetition.
That is, in the conventional kamaboko type main discharge electrode, the laser gas must be circulated from one side of the main discharge electrode facing each other to the other side due to its configuration. In this case, fresh laser gas is provided on one side of the main discharge electrode, but as the laser gas flows to the other side of the main discharge electrode, the concentration of ozone and oxygen increases due to the main discharge between the main discharge electrodes. Therefore, arc discharge is likely to occur, and high repetition is difficult.

FIG. 3 shows a second embodiment of the present invention. In this embodiment, an insulating plate 31 is provided horizontally at a position near the lower center of the laser container 1, and two sheets arranged in parallel thereto are provided. Base plates 2 and 3 are fixed upright. That is, the base plates 2 and 3 have an arrangement structure in which the base plates 2 and 3 shown in FIG. 1 are rotated 90 degrees counterclockwise.
The blower means 25 in this embodiment includes a single circulation fan 26 disposed below the insulating plate 31 and a heat exchanger 28 for cooling the laser gas that has passed through the discharge space. When 26 is rotated, the laser gas in the laser container 1 can be circulated clockwise along the inner surface of the laser container.
That is, the laser gas sent out by the circulation fan 26 flows through the through holes 4c and 5c of the base plates 2 and 3 and flows between the coiled electrodes 4b and 5b in the axial direction of the coiled electrodes. After being cooled by the heat exchanger 28, it is sent again by the circulation fan 26.
Other configurations are the same as those in the first embodiment described above, and the same or corresponding parts as those in the first embodiment are denoted by the same reference numerals.
In the second embodiment, it is obvious that the same effect as the first embodiment can be obtained.

In each of the above embodiments, the through holes 4c and 5c are formed in the base plates 2 and 3, respectively, and the laser gas is circulated between the plurality of coil electrodes in the axial direction of the coil electrodes. However, it is not limited to this. For example, with regard to the first embodiment, a plurality of air ducts are provided on the lower surface of the base plate 2, and openings of each air duct are provided between the plurality of coiled electrodes so that laser gas flows from each opening in the axial direction of the coiled electrodes. You may do it. Alternatively, a honeycomb-shaped metal plate that originally has through holes may be used as the base plate.
Further, in each of the above embodiments, the TEA type CO ₂ laser oscillator has been described as the pulse gas laser oscillator. However, the present invention is not limited to this, and the pulse gas laser oscillator such as an excimer laser, a CO laser, or a metal vapor laser is used. Can also be applied.

Sectional drawing which shows 1st Example of this invention. The top view of the part of the baseplate 2 shown in FIG. Sectional drawing which shows 2nd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser container 2, 3 Base plate 4, 5 Main discharge electrode 4a, 5a Support member 4b, 5b Coiled electrode 4c, 5c Through-hole 6 Pre-ionization electrode 7 Insulation member 11 DC high voltage pulse power supply 12 DC high voltage pulse power supply 25 for trigger Means 26 Circulation fan

Claims (4)

A laser container filled with a laser gas; a main discharge electrode disposed opposite to the inside of the laser container; and a DC high-voltage pulse power source for applying a voltage between the main discharge electrodes to discharge the battery, In a pulse gas laser oscillator in which a laser gas is excited to cause laser oscillation by discharging between main discharge electrodes by a pulse power source,
The main discharge electrodes, their respective and a coil-shaped electrode of the multiple, and pulsed gas laser oscillator of the distal ends of the coiled electrodes are opposed to each other, characterized in that the arranged.   A preionization electrode is provided on one of the coiled electrodes arranged to face each other and on the base side away from the tip portions facing each other via an insulating member. 2. The pulse gas laser oscillator according to claim 1, wherein preionization is performed between the two.   The pulse according to claim 1 or 2, wherein a blowing means for circulating the laser gas is provided, and the laser gas is circulated in the axial direction of the coiled electrode from between the plurality of coiled electrodes. Gas laser oscillator. Two base plates each made of a conductive material are disposed in the laser container, and a plurality of support members each made of an insulating material are erected on each base plate, and the support member erected on one base plate and the other The support members provided on the base plate are disposed so as to face each other, the plurality of coiled electrodes are wound around the support members, the coiled electrodes are connected to the base plates, and the base plates are further connected to the base plate. claims 1 to pulsed gas laser oscillator according to claim 3, characterized in that connected to a DC high-voltage pulse power supply.

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