JPH07183600A - Gas laser equipment - Google Patents

Abstract

PURPOSE:To make stable generation of a laser light of a large output possible by ionizing a discharge space part uniformly preliminarily and by igniting a main discharge. CONSTITUTION:In gas laser equipment wherein a laser light is generated by exciting a gas laser medium by a discharge, a laser tube 1 wherein the gas laser medium is held, main electrodes composed of a negative electrode 21 and a positive electrode 3 disposed oppositely in this laser tube, and a preliminary ionization means for ionizing a discharge space part between the negative and positive electrodes preliminarily prior to a main discharge generated by the main electrodes, are provided. Either the negative or positive electrode of the main electrodes is constructed of a tubular dielectric 21a which is provided with a metal member 21 having a vacant hole 21b in the part of the outer peripheral surface being opposite to the other electrode, at least, while the preliminary ionization means is a corona electrode constituted of a metal wise 31a of which the opposite ends are connected to the other electrode and of which the middle part is inserted through the dielectric.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas laser device which excites a gas laser medium by discharge to generate laser light.

[0002]

2. Description of the Related Art Generally, in a gas laser apparatus, a cathode and an anode constituting a main electrode are arranged in a laser tube in which a gas laser medium is housed so as to face each other, and a discharge space between them is formed. The main laser is ignited to excite the gas laser medium to generate laser light.

Before the main discharge is ignited in the discharge space, the discharge space is pre-ionized so that the main discharge is easily uniformly ignited in the discharge space. In the nitrogen gas laser device in which the nitrogen gas is sealed in the laser tube at a predetermined pressure, there is known a device in which preionization of the discharge space portion is performed by corona discharge.

FIG. 5 and FIG. 6 show such a conventional nitrogen gas laser device. That is, reference numeral 1 in the figure is a laser tube having an airtight structure in which nitrogen gas as a gas laser medium is enclosed. In this laser tube 1, a cathode 2 and an anode 3 which form a main electrode are arranged so as to be opposed to each other in the vertical direction. A main discharge is ignited between the anode 2 and the cathode 3 by a capacity transfer type control circuit 4 as described later.

The control circuit 4 has a DC high voltage power source 5. A gap switch 6 is connected in parallel to the high-voltage power supply 5, and the cathode 2 and the inductance 8 are connected to the negative side via a charging capacitor 7.
The anode 3 is connected to the ground side of the high voltage power supply 5. The inductance 8 is a peaking capacitor 9
Are connected in parallel.

The gap switch 6 has a pair of electrodes 6a separated by a predetermined distance and a trigger electrode 6b provided between these electrodes, and the trigger electrode 6b is provided with 20k.
By applying a pulse voltage of about V, the pair of electrodes 6
An arc discharge occurs between a and a short circuit occurs.

Discharge space 1 between the cathode 2 and the anode 3
The preionization means for preionizing 0 is composed of a pair of corona electrodes 11. As shown in FIG. 6, the corona electrode 11 includes a metal wire 11a such as a copper wire bent in a U-shape and a glass dielectric tube 11b in which the metal wire 11a is inserted.
Are formed from.

A pair of corona electrodes 11 are provided on both sides of the anode 3 in the width direction, both ends of each metal wire 11a are electrically connected to both ends of the anode 3 in the longitudinal direction, and both sides thereof are the main electrodes 2. 3 is curved outward in the width direction.

In such a structure, when the high-voltage power supply 5 operates, the charging capacitor 7 and the inductance 8 are connected to L.
The electric charge is stored in the charging capacitor 7 by the C circuit.
When the pulse voltage is applied to the trigger electrode 6b at a predetermined timing, the gap switch 6 is closed, the charge stored in the charging capacitor 7 is transferred to the peaking capacitor 9, and the high voltage is applied to the cathode 2 and the anode 3. Is charged.

At the same time, electrons flow between the cathode 2 and the U-shaped intermediate portion of the corona electrode 11, and the electrons generate corona discharge on both sides in the width direction of the cathode 2. As a result, the discharge space 10 is preionized, and the cathode 2 and the anode 3 are
Therefore, the glow discharge is ignited between these electrodes, and the nitrogen gas is excited by the glow discharge to generate laser light.

By the way, according to such a structure, the glow discharge for preionization is generated only in a limited region of the cathode 2 facing the corona electrode 11, that is, only on both sides in the width direction of the cathode 2. Therefore, the entire discharge space 10 is unlikely to be uniformly preionized by corona discharge.
Due to the preionization, the uniformity of the main discharge ignited in the discharge space portion 10 is also lowered, and the laser output is sometimes lowered. Further, since the corona electrode 11 has a shape curved outward in the width direction of the main electrode as shown in FIG.
There have been cases where the width of the tube 1 cannot be reduced.

[0012]

As described above, in the conventional gas laser device, the corona discharge for pre-ionizing the discharge space is generated only in a partial region of the main electrode, so that the uniformity of the main discharge is deteriorated. However, this may lead to a decrease in laser output.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a gas laser device capable of uniformly preionizing the discharge space portion by corona discharge.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is a gas laser apparatus for generating laser light by exciting a gas laser medium by electric discharge, in which the gas laser medium is housed. Laser tube, a main electrode composed of a cathode and an anode arranged in the laser tube so as to face each other, and a discharge space between the cathode and the anode. Preliminary ionization means for performing preliminary ionization prior to the above, and one of the cathode and the anode of the main electrode is provided with a metal member having a hole in at least a portion of the outer peripheral surface facing the other electrode. It is characterized in that it is made of a cylindrical dielectric and that the preionization means is a corona electrode whose both ends are connected to the other electrode and a middle portion is made of a metal wire inserted into the dielectric.

[0015]

According to the above structure, the corona discharge is uniformly ignited between the corona electrode and the metal member forming one electrode, and the electrons generated by the corona discharge are vacant holes formed in the metal member. To uniformly preionize the discharge space.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. Incidentally, the same parts as those of the conventional structure shown in FIGS. The gas laser device of the present invention differs from the conventional structure in the cathode and the corona electrode. That is, the cathode 21 is formed by providing a metal member 21c having holes 21b on the outer peripheral surface of a dielectric material 21a having both end surfaces formed in a cylindrical shape from heat-resistant glass or alumina ceramics.

Both ends of the dielectric 21a are closed, and a through hole 21d is formed at the center of both ends. The metal member 21c is formed by spattering a metal such as nickel or copper in a mesh shape on the entire outer peripheral surface of the dielectric 21a, and the metal member 21c is electrically connected to the control circuit 4.

Although the metal member 21c is provided on the entire outer peripheral surface of the dielectric 21a, instead of the metal member 21c, the dielectric 21a is provided.
It may be provided only on the half circumference of the side facing the anode 3, and a band-shaped metal having holes 21b formed therein may be spirally wound or further formed into a cylindrical metal mesh without using sputtering. May be fitted on the outside.

On the other hand, the corona electrode 31 has a diameter of about 0.5 mm and is made of the same material as the anode 3 such as nickel metal wire 31.
The metal wire 31a is bent in a substantially U-shape. Both ends of the metal wire 31a are welded to both end faces of the anode 3 in the longitudinal direction, and an intermediate portion is inserted into the inside of the dielectric 21a through the through holes 21d of both end faces thereof. Therefore, the middle part of the metal wire 31a is located substantially in the radial center of the dielectric 21a.

It should be noted that both ends of the metal wire 31a protruding to the outside of the dielectric 21a may be inserted through the glass dielectric tube 11b as in the conventional structure. According to the gas laser device having such a configuration, when the voltage for preionization is applied between the metal wire 31a of the corona electrode 31 and the dielectric 21a of the cathode 21, the corona discharge is generated between them. Is fired. As shown in FIG. 3, the electrons E generated by this corona discharge pass through the holes 21b formed in the metal member 21b.

Facing the anode 3 of the metal member 21c,
The electrons E that have passed through the holes 21c in the range of approximately 180 degrees in the circumferential direction flow out into the discharge space 10 between the cathode 21 and the anode 3 and preionize the discharge space 10. That is, the electrons E that have passed through the holes 21c in the range of approximately 180 degrees in the circumferential direction.
Will pre-ionize the entire discharge space 10 indicated by W in FIGS. 1 and 3 in the width direction substantially uniformly.

By the electrons E generated by the corona discharge,
If the discharge space 10 is preionized almost uniformly, the main discharge (glow discharge) subsequently ignited between the cathode 21 and the anode 3 is also uniformly ignited in the entire discharge space 10. Therefore, laser light can be generated stably and at high output by the main discharge.

Further, since the metal wire 31a of the corona electrode 31 is inserted through the central portion of the dielectric 21a of the cathode 21, the metal member 21c provided on the outer peripheral surface of the dielectric 21a from the metal wire 31a. The distance to is almost the same at any position in the circumferential direction. Therefore, since the intensity of the corona discharge generated between the metal wire 31a and the metal member 21c becomes uniform in the circumferential direction of the cathode 21,
As a result, the direction of the width W of the discharge space 10 is uniformly preionized.

As the metal member, as shown in FIG. 4, a metal cylinder 4 in which a material such as nickel or copper is formed in a cylindrical shape in advance and a large number of holes 41a are formed in the peripheral wall thereof.
1, and the metal cylinder 41 is shown in FIG.
It may be fitted onto a.

The thickness of the material forming the metal cylinder 41 is
An experiment was conducted using 0.3 mm, the shape of the holes 41a as a diameter of 100 μm, and the aperture ratio as 50%. As a result, a laser light with high output could be stably obtained.

The shape of the cathode is not limited to a cylindrical shape, but may be a semi-cylindrical shape or an elliptical shape. Further, the metal member may not be provided on the entire circumference of the tubular shape, but may be provided only on about half circumference facing the anode. In addition, gas
The present invention is applicable not only to the nitrogen gas laser device but also to an excimer laser or a TEACO ₂ laser.

[0027]

As described above, according to the present invention, one of the cathode and the anode forming the main electrode has a metal member having a hole in a portion of the outer peripheral surface thereof facing at least the other electrode. The preionization means, which is formed from a provided cylindrical dielectric and preionizes the discharge space, has a corona electrode made of a metal wire whose both ends are connected to the other electrode and whose middle part is inserted into the dielectric. And

Therefore, the electrons generated by the corona discharge between the metal member and the metal wire pass through the holes of the metal member and pre-ionize the entire discharge space substantially uniformly. As a result, the main discharge, which is ignited between the cathode and the anode following the preliminary ionization, is also uniformly ignited, so that the laser light of high output can be stably generated. Further, since the corona electrode does not need to project in the width direction of the main electrode, the width dimension of the laser tube can be reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a gas laser apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view of a state in which a cathode and an anode are also arranged.

FIG. 3 is an enlarged cross-sectional view of the same cathode.

FIG. 4 is a side view of a metal member of a cathode showing another embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional gas laser device.

FIG. 6 is a perspective view of the arrangement state of the cathode and the anode.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laser tube, 3 ... Anode, 10 ... Discharge space part, 21 ... Cathode, 21a ... Dielectric material, 21b ... Hole, 21c ... Metal member, 31 ... Corona electrode, 31a ... Metal wire.

Claims (3)

[Claims] 1. A gas laser device for generating laser light by exciting a gas laser medium by discharge, and a laser tube containing the gas laser medium, and the laser tube.
A main electrode composed of a cathode and an anode arranged to face each other in the tube, and a preionization means for preionizing the discharge space between the cathode and the anode prior to the main discharge generated in the main electrode. One of the cathode and the anode of the main electrode comprises a cylindrical dielectric body provided with a metal member having a hole in a portion of the outer peripheral surface facing at least the other electrode, A gas laser device, wherein the preionization means is a corona electrode whose both ends are connected to the other electrode and whose middle portion is made of a metal wire inserted into the dielectric body. 2. The gas laser device according to claim 1, wherein the metal member is formed by sputtering a metal on the outer peripheral surface of the cylindrical dielectric of one of the electrodes. 3. The gas laser device according to claim 1, wherein the dielectric has a cylindrical shape.