JPH0846274A - Gas laser equipment - Google Patents

Abstract

PURPOSE:To provide a gas laser equipment which enables uniformly preliminary ionization of discharge space by using X-ray. CONSTITUTION:A gas laser equipment which generates laser light by discharging and exciting gas laser medium consists of the following; an airtight vessel 21 in which the gas laser medium is sealed, a pair of main electrodes 24, 25 which are arranged in the airtight vessel so as to be faced and isolated, an X-ray tube 38 which performs preliminary ionization of a discharge space S between the main electrodes 24, 25 by using X-ray before igniting the discharge of the space between a pair of the main electrodes, and an attenuation member 41 which is arranged so as to face the X-ray tube 38 and controls X-ray radiated from the X-ray tube 38 to obtain uniform distribution.

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 Prior Art In a gas laser device such as an excimer laser or a CO ₂ laser, a main discharge is ignited before a main discharge is ignited in a discharge space between a pair of main electrodes arranged in an airtight container. Pre-ionization of the discharge space is performed. There are various methods for preionization, but part 1
As a method, a method using X-ray is known.

9 (a) and 9 (b) show a conventional gas laser device. In the figure, 1 is an airtight container. This airtight container 1
A cathode 2a and an anode 2b, which are a pair of main electrodes, are arranged in the interior so as to face each other with a space therebetween. In the anode 2b arranged on the upper side, a concave portion 3 opened to the back side is formed over the entire length in the length direction. Airtight container 1 facing this recess 3
A transparent window 4 for transmitting X-rays is formed on the peripheral wall of the.
In the transmission window 4, a plurality of sealed X-ray tubes 5 are arranged so as to face each other. The X-ray tube 5 is formed by arranging a cathode 6b and an anode 6c in a tube 6a made of a material that transmits X-rays.

When X-rays are output from the X-ray tube 5, the X-rays pass through the concave portion 3 of the anode 2b and pre-ionize the discharge space S between the cathode 2a and the anode 2b. .
When the preionization proceeds, the main discharge is ignited between the pair of main electrodes, so that the gas laser medium is excited and laser light is generated.

In order to carry out laser oscillation with high output and high efficiency, it is necessary to make the distribution of X-rays in the discharge space S as uniform as possible. When the distribution state of X-rays is non-uniform, pre-ionization is also non-uniform, and discharge concentration occurs in a portion having a large initial electron density difference during main discharge, resulting in instability.

[0006] By the way, the conventional gas laser having the above-mentioned structure is used.
X emitted from each X-ray tube 5 in the device
The dose has a Gaussian distribution in which the dose is large at the center of each X-ray tube 5 and decreases from the center to the outside.

Therefore, the distribution of the X-ray dose in the discharge space S is non-uniform because it has a corrugated shape in which a large number of portions and a small amount are alternately repeated in the longitudinal direction. Pre-ionization is also non-uniform. As a result, as described above, discharge concentration may occur in a portion where the density difference of initial electrons in the main discharge is large, and the output laser light may become unstable.

[0008]

As described above, when pre-ionizing the discharge space by X-rays, the distribution of X-rays output from the X-ray tube is large in the central part and decreases as it goes to the periphery. However, there was a case where uniform preionization could not be performed depending on the distribution state.

The present invention has been made in view of the above circumstances. An object of the present invention is to provide a gas laser capable of performing relatively uniform preionization when the discharge space is preionized by X-rays. To provide a device.

[0010]

In order to solve the above-mentioned problems, the present invention is a gas laser device for generating laser light by exciting a gas laser medium by discharge, in which the gas laser medium is enclosed. The airtight container, the pair of main electrodes arranged to face each other in the airtight container, and the discharge space between the main electrodes are separated by X before the discharge is ignited between the pair of main electrodes.
It is characterized by comprising: preionization means for preionization by means of radiation, and control means arranged so as to face the preionization means, for controlling the distribution state of X-rays emitted from the preionization means to be uniform. And

[0011]

According to the above construction, by controlling the distribution state of the X-rays from the preionization means to be uniform by the control means, the preionization in the discharge space is made uniform, thereby stabilizing the laser light. It is possible to oscillate in the state.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The gas laser device shown in FIG.
The airtight container 21 has a double-cylinder shape and includes an inner cylinder 21b and a cylinder 1a. A gas laser medium is enclosed in the airtight container 21, and the gas laser medium can be circulated in the direction of the arrow in an annular circulation path formed in the airtight container 21 by a blower 22 disposed inside. It has become.

A pair of heat exchangers 23 are arranged in the circulation path, and an anode 24 and a cathode 25 which are main electrodes are provided.
And are vertically opposed to each other and are arranged along a direction orthogonal to the flow direction of the gas laser medium. The anode 24 is attached to an upper holder 26 provided in the outer cylinder 21a, and the cathode 25 is attached to a lower holder 27 provided in the inner cylinder 21b. A peaking capacitor 28 is provided on the back side of the cathode 25, and the cathode 25 and the anode 24 are connected to a conductor 29 via the peaking capacitor 28. A high voltage pulsed from a high voltage power source (not shown) is input to the anode 24 and the cathode 25 via the conductor 29.

The anode 24 is formed with a recess 31 open to the back side thereof. A through hole 32 having a length substantially corresponding to the concave portion 31 is formed at a position corresponding to the concave portion 31 of the upper holding body 26, and a housing step portion 33 is formed around the through hole 32. . Preliminary ionization means 34 is provided on the storage step portion 33. The preionization means 34 has a case 35 made of a metal having a high thermal conductivity such as copper. A circulation path 36 for circulating a coolant such as cooling water is spirally formed on the peripheral wall of the case 35.

Further, inside the case 35, a plurality of hollow cylindrical accommodating portions 37 are defined by partition walls 35a provided at predetermined intervals in the longitudinal direction. Case 3 above
A through hole 37a is formed in the bottom portion of 5 along the entire length in the longitudinal direction. The through hole 37a communicates with the through hole 32 formed in the upper holding body 26. An X-ray tube 38 is stored in each storage portion 37.

The X-ray tube 38 is KO as shown in FIG.
It is made of metal such as V, tantalum or tungsten in a columnar shape, and has a cylindrical anode on its inner wall.
A door 39 is provided. An X-ray transmission window 41 made of beryllium is formed on one end surface of the anode 39, and the other end surface is closed by an insulating member 42 made of a glass material or the like.

Inside the anode 39, a cathode 43 is provided.
And the both ends of the cathode 43 are connected to the insulating member 4
It is derived airtightly from 2. The cathode 43 is an impregnated cathode formed by spirally forming a wire rod in which tungsten is impregnated with barium.
It is housed concentrically inside. The X-ray tube 38 is housed in each housing 37 of the case 35 with the transmission window 41 facing the through hole. When the X-ray tube 38 is accommodated in the accommodating portion 37, the outer peripheral surface of the node 39 is X-shaped.
It is in a state of being in contact with the inner peripheral surface of the housing portion 37 via the wire tube 38. A heater circuit 44 is connected to the cathode 43. Further, a negative high voltage pulse is applied to the cathode 43 from an X-ray pulse power source (not shown). The X-ray tube 38 is grounded via the case 35.

At the position corresponding to the axial center of each X-ray tube 38 in the recess 31 of the anode 24, an attenuation member 41 as a control means for controlling the distribution state of the X-ray dose is arranged. There is. The attenuating member 41 is made of a material that attenuates the amount of X-ray transmission, such as aluminum, and the amount by which the X-ray is attenuated by the attenuating member 41 can be set by the thickness and size. That is, the X-ray transmission amount is inversely proportional to the thickness of the attenuation member 41, and the attenuation range in the region output from the X-ray tube 38 can be set depending on the size.

In this embodiment, as shown in FIG. 7A, the damping member 41 has a length dimension L set to be substantially the same as the width direction of the recess 31, and a width dimension W of the X-ray. Tube 3
The shape of the strip is set to about one-third of the diameter of 8.

FIG. 6 shows the relationship between the thickness of the aluminum damping member 41 and the amount of X-ray transmission. As can be seen from this graph, by setting the thickness of the damping member 41 to 1 mm,
It can be seen that the amount of X-ray transmission is attenuated by about half. The vertical axis is an arbitrary unit.

FIGS. 4A and 4B show the distribution of X-rays in one X-ray tube 38 with and without the damping member 41 in the X-ray radiation direction. As shown in FIG. 3B, when the damping member 41 is not provided, the X-ray emitted from the X-ray tube 38 has a Gaussian distribution,
As shown in (a), the center part is attenuated in the case where there is one, so that it is averaged as compared with the case where it does not exist.

5 (a) and 5 (b) show X-rays in the longitudinal direction of the anode 24, with and without the damping member 41 corresponding to each X-ray tube 38. Shows the distribution state of. As shown in FIG.
When No. 1 is not arranged, there is a wavy distribution that maximizes the radiation dose in the central portion of each X-ray tube 38, but the attenuation member 41 is arranged as shown in FIG. In this case, the X-ray dose in the central portion is attenuated by each attenuation member 41, so that the distribution state is averaged.

FIGS. 7B to 7E are modified examples of the damping member 41. The same figure (b) shows a stepped step portion 41a formed at both ends of the damping member 41, and the same figure (c) shows that both end portions are similarly formed into an arcuate R portion 41b. FIG. 6D shows a stepped portion 41c formed over the entire peripheral portion of the damping member 41, and FIG. 8E shows an R portion 41d formed over the entire peripheral portion.

As described above, by changing the shape of the end portion of the damping member 41, the attenuation of X-rays by the damping member 41 can be controlled. That is, by making the end shape of the attenuating member 41 into a stepped shape or an arcuate shape, the amount of attenuation of X-rays at the end can be reduced, so that the distribution state of X-rays transmitted through the attenuating member 41 can be further improved. , Can be made uniform.

According to the gas laser device having such a configuration, the X-ray output from each X-ray tube 38 is attenuated in the X-ray dose by the attenuation member 41 arranged in the concave portion 31 of the anode 24, and the anode 24 is aforesaid. And is incident on the discharge space S.

The X-rays incident on the discharge space S are attenuated by the attenuating member 41, and the amount of the central portion thereof is reduced.
The distribution is made uniform as shown in (a).

If the distribution amount of the X-rays incident on the discharge space S is made uniform, the preionization density of the discharge space S by the X-rays is also made uniform. Therefore, the main discharge ignited between the anode 24 and the cathode 25 is stabilized by the advance of the preionization, so that the laser oscillation can be performed with high output and high efficiency. Further, by stabilizing the main discharge, not only a high repetition operation is possible, but also the life of the gas laser medium and the electrodes 24, 25 can be extended.

FIGS. 8A and 8B show another embodiment of the present invention. In this embodiment, as shown in FIG.
The damping member 41A provided in the recess 31 of No. 4 is set to have a length corresponding to only the central portion of the X-ray tube 38 also in the width direction of the anode 24. In this case, the shape of the damping member 41 may be a disk shape or a square shape.

With such a structure, the X-ray transmission amount can be made uniform not only in the longitudinal direction of the anode 24 but also in the width direction thereof, as shown in FIG.
Accordingly, the main discharge can be stabilized.

The damping member 41A may be disk-shaped or square-shaped, and its end may be stepped or arc-shaped as shown in FIGS. 7 (d) and 7 (e). The shape may be such that the X-ray dose from the central portion of 38 is attenuated and the width direction as well as the longitudinal direction can be made uniform.

[0031]

As described above, according to the present invention, in the gas laser device for preionizing the discharge space portion with the X-rays from the preionization means, the distribution state of the X-rays in the discharge space portion is controlled to be uniform. I tried to turn it on. Therefore, the preliminary ionization density in the discharge space can be made uniform, so that the main discharge can be stabilized accordingly and a large output and high efficiency laser oscillation can be achieved.

[Brief description of drawings]

FIG. 1 is a sectional view showing the overall configuration of an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the main part of the same.

FIG. 3 is a configuration diagram of an X-ray tube.

FIG. 4A is an explanatory diagram of an X-ray distribution state when there is a damping member, and FIG. 4B is an explanatory diagram of an X-ray distribution state when there is no damping member.

5A is an explanatory view of an X-ray distribution state along the longitudinal direction of the anode when there is a damping member, and FIG. 5B is a X-ray distribution state along the longitudinal direction of the anode when there is no damping member. Explanatory drawing of.

FIG. 6 is a graph showing the relationship between the thickness of the damping member and the amount of X-ray transmission.

7 (a) to 7 (e) are explanatory views showing various forms of the damping member.

FIG. 8 is an explanatory diagram for controlling the amount of X-ray transmission in the width direction of the anode.

FIG. 9A is a sectional view of a conventional gas laser device,
(B) is sectional drawing which similarly follows a longitudinal direction.

[Explanation of symbols]

21 ... Airtight container, 24 ... Anode, 25 ... Cathode, 38 ... X-ray tube (pre-ionization means), 41 ... Damping member (control means).

Claims (4)

[Claims] 1. A gas laser apparatus for generating laser light by exciting a gas laser medium by electric discharge, and an airtight container in which the gas laser medium is enclosed, and the airtight container is disposed so as to be opposed to and spaced from the airtight container. A pair of main electrodes, and a preionization means for preionizing the discharge space between the main electrodes by X-rays prior to igniting a discharge between the pair of main electrodes, and a preionization means facing the preionization means. Control means for controlling the distribution state of the X-rays emitted from the preionization means to be uniform.
The device. 2. The gas laser device according to claim 1, wherein the control means comprises an attenuation member for attenuating the amount of X-ray transmission. 3. The gas laser device according to claim 2, wherein the attenuating member is provided in a portion having a large X-ray dose in an X-ray radiation region. 4. The pre-ionization means is a plurality of X-ray tubes arranged on one rear surface side of the main electrode along a longitudinal direction thereof at predetermined intervals, and the control means is provided for each X-ray tube. The gas laser device according to claim 1, wherein the gas laser device comprises a plurality of attenuating members which are arranged to face each other and attenuate the X-ray transmission amount.