JPH11340546A - Gas laser tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow larger conductance of a discharge channel for a gas laser tube, while occurrence of discharge is prevented in a gas feedback channel. SOLUTION: A gas laser tube comprises a cathode, a discharge tube, an anode, a cylindrical enclosure 9 for sealing gas, and an optical resonator comprising a pair of mirrors for sandwiching them. The cylindrical discharge thin tube comprises a discharge channel 10 which is a space for discharge at its axial part, as well as several gas feedback channels 12 which are through-holes of several mm in diameter for enclosing the space for discharge. Here, several or tens of discs 11 of several mm in thickness, where a hole of several mm in diameter is provided at its center, are inserted in the cylindrical enclosure, and several grooves of the discs are provided evenly on the side surface of the disc in the radial direction while being spirally arranged in axial direction, so that a part of the groove of the discs overlaps each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas laser tube, and more particularly, to a structure of a discharge capillary.

[0002]

2. Description of the Related Art As shown in FIG. 5, a gas laser tube has a cathode 101, a discharge thin tube 102 and an anode 103 arranged in tandem at a predetermined interval on the same axis and a high reflection mirror with an output mirror 104 so as to sandwich the same. It has a configuration in which the mirror 105 is arranged as an optical resonator. The cathode 101 is
It is separated from the outside air by the cathode envelope 106 and the metal ring 107, and the discharge tube 10 is separated by the metal ring 107.
2 is connected. Further, the discharge thin tube 102 is hermetically sealed in an envelope 109 provided with a radiation fin 108 on the outer periphery.

In general, the discharge capillary 102 has a columnar shape made of, for example, Berria ceramic, and as shown in FIG. 5, a thin cylindrical hole or discharge path 110 provided at the center portion and surrounding the same. The gas return path 111 is constituted by thin cylindrical holes arranged as described above.

In the above-described gas laser tube, the cathode 1
By applying a trigger voltage between 01 and the anode 103,
Discharge occurs in the discharge path 110 between the electrodes. Due to this discharge, plasma is generated in the discharge tube 102, and the laser medium in the tube is excited by the plasma to generate visible light or light of an arbitrary wavelength. This light is transmitted to the high reflection mirror 105 as an optical resonator. It is amplified by being repeatedly reflected between the output mirror 104 and output as a laser output.

Therefore, the length and size of the discharge path 110 are important characteristics that determine the laser output. Also,
It is also a parameter that determines the characteristics of light. Gas return path 1
Numeral 11 is for circulating the gas in the laser tube. The discharge prevents the gas in the tube from being flushed from the cathode side to the anode side, so that the gas on the cathode side becomes diluted and the discharge in the discharge path 110 cannot be continued. For this purpose, the gas is returned to the cathode side.

Meanwhile, in order to maintain the discharge in the discharge path 110, it is necessary to make the conductance in the return path 111 equal to or larger than that in the discharge path 110.

[0007]

However, when the conductance is to be increased by using the discharge thin tube 102 having the structure shown in FIG. 6, the diameter of the gas return path 111 is equal to the diameter of the discharge path 110 or the diameter of the discharge path 110 is increased. If you use a method to make it larger than the diameter of
The possibility that discharge occurs in the gas return path 111 increases, and when discharge occurs in the gas return path 111,
If a method of increasing the number of gas return paths 111 using a laser oscillation output cannot be obtained,
When the method of increasing the number of gas return paths 111 is used, the heat transfer surface decreases, heat is less likely to be transmitted, and the laser tube may be broken.
It is known that various problems occur such that the strength of the discharge capillary 102 is reduced and the laser tube is easily damaged by external force.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem. The object of the present invention is to reduce the conductance of a gas return path of a discharge capillary of a gas laser tube while preventing the discharge from occurring in the gas return path. It is an object of the present invention to provide a gas laser tube which can be made larger than the above and can obtain a stable laser oscillation output.

[0009]

SUMMARY OF THE INVENTION The present invention has been made based on the above-mentioned problems, and comprises a cathode, a discharge tube made of an insulator, an anode, a cylindrical envelope for filling gas, and
An optical resonator composed of a pair of mirrors so as to sandwich them, the discharge capillary has a columnar shape, has a space for discharge at the tube axis, and returns gas so as to surround the space for discharge. In the gas laser tube having a passage, the discharge thin tube is provided in the cylindrical envelope with a large number of insulating disks having a central through hole connected thereto, and the side surface of each of the insulating disks extends along the tube axis direction. A gas laser tube provided with at least one groove, wherein the grooves of the adjacent insulating disks partially overlap each other to form a non-linear gas return path.

That is, a discharge thin tube used for a gas laser tube is divided into a disk having a thickness of 5 to 10 mm, and grooves having a width of several mm and a depth of several mm are provided on the side surfaces of each disk at several locations in a circumferential direction. So that the grooves overlap at least partially
Because it is arranged spirally in the axial direction in the cylindrical envelope,
The occurrence of discharge in the gas return path is reduced.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic sectional view showing a gas laser tube of the present invention. As shown in FIG. 1, in a gas laser tube, a cathode 1, a discharge capillary 2 and an anode 3 are arranged in tandem at a predetermined interval on the same axis, and an output mirror 4 and a high reflection mirror 5 are optically resonated so as to sandwich the same. It has a configuration arranged as a vessel. The cathode 1 is separated from the outside air by a cathode envelope 6 and brazed to the discharge capillary 2 by a metal ring 7. In addition, the discharge capillary 2
Are hermetically sealed in a cylindrical envelope 9 in which heat radiation fins 8 are brazed to the outer periphery.

The discharge capillary 2 has a central through hole, ie, a central opening, which has an opening of a predetermined diameter used as a discharge path 10, ie, a hole having a diameter of several mm. It has a structure in which a plurality of insulating disks 11 are stacked, and a predetermined number are inserted into the envelope 9.
The opening of the disk 11 on the anode side of the disk closest to the anode 3 is formed in a tapered shape whose diameter increases toward the anode 3. Similarly, the disk 11
The opening on the cathode side of the disk located closest to the cathode 1 is formed in a tapered shape whose diameter increases toward the cathode 1.

A plurality of grooves used as a gas return path 12 are equally arranged in the circumferential direction on the side surface, that is, the cylindrical surface of the disk 11. The circumferential width of the groove 12 is several mm, and the radial length, that is, the depth from the side surface is several m.
m. In addition, the size of the portion where the disk 11 is cut off when viewed from a plane perpendicular to the discharge direction, that is, the axial direction, is larger than the diameter of the discharge path 10, that is, the cross-sectional area of the hole at the center of the disk 11. So, it is formed.

More specifically, as shown in FIG. 2, at least a part of the grooves 12 provided on the circumference of each disk overlap each other, and each disk 11 has a spiral shape when viewed from the axial direction. It is arranged so that FIG. 2 shows the arrangement of the grooves 12 of the disk 11, that is, the spirals of the grooves 12 in an easy-to-understand manner. The disks 11 are connected in the axial direction in the envelope 9, that is, are arranged without gaps.

The number of disks 11 inserted into the envelope 9 is set according to the required laser output and the light characteristics required for the output laser light. The adjacent disk 1
The area where the one groove 12 overlaps can be adjusted based on the conductance defined in relation to the pressure and the calorific value of the gas used, and is set by rotating the disk 11 in the circumferential direction. The laser output is the length of the discharge path 10 of the discharge capillary 2, that is, the disk 1 inserted into the envelope 9.
It can be adjusted by changing the number of 1s.

In the above-described gas laser tube, the cathode 1
By applying a trigger voltage between the electrode and the anode 3, a discharge occurs in the discharge path 10 between the electrodes. Due to this discharge, plasma is generated in the discharge tube 2, and the plasma excites a laser medium in the tube to generate visible light or light of an arbitrary wavelength. This light is transmitted to the high-reflection mirror 5 as an optical resonator. It is amplified by being repeatedly reflected between the output mirror 4 and output as a laser output.

When the laser medium is excited in the discharge path 10 of the discharge tube 2 to generate light, the discharge gas in the tube is moved from the cathode 1 to the anode 3 by the body force of electrons.
Is washed away to the side of. From this, it has already been described that high conductance is required in the gas return path in order to maintain laser oscillation.

In the present invention, the discharge path 10 is constituted by a plurality of disks 11, and grooves 12 provided at equal intervals on the outer periphery of the disk 11 are formed so that a part of the grooves are overlapped with each other.
Are arranged so as to be spiral when viewed from the axial direction, it is possible to obtain a return path with high conductance and no discharge.

The gas return path, that is, the spiral groove 12 allows the gas in the laser tube to be reliably returned to the cathode 1 side, so that the discharge gas on the cathode 1 side in the tube is diluted. Stopping of laser oscillation is prevented. In addition, since the discharge thin tube 2 is constituted by the plurality of disks 11 described above and the plurality of grooves 12 are provided on the outer periphery thereof,
The heat conduction of the discharge tube 2 can be enhanced, and the laser tube is prevented from being damaged by the heat generated by the discharge. Also,
The strength of the discharge capillary 2 can be increased, and the laser tube can be prevented from being damaged by external force.

Therefore, it is possible to provide a gas laser tube capable of outputting a stable laser output for a long time. FIG. 3 is a schematic view showing a modified example of the groove 12 of the disk 11 used for the discharge capillary 2. As shown in FIG. 3A, the open end of the groove 12 provided in each disk 11, that is, the cutting of the disk 11. It is characterized in that both end portions on the side close to the surface are wider than near the center in the longitudinal direction of the disk 11.

That is, when a plurality of disks 11 as shown in FIG. 3A are inserted into the envelope 9 in the same manner as described above with reference to FIG. 2, as shown in FIG. In addition, a region where each groove 12 overlaps at the connection portion is widened, and a spiral gas return path is provided in which the phase of the groove 12 provided in each disk 11 is more greatly changed.

According to this configuration, it is possible to further reduce the possibility of occurrence of discharge in the gas return path while securing the same conductance as that of the example of the discharge capillary shown in FIG. FIG.
FIG. 3 is a schematic view showing another embodiment of the groove 12 of the disk 11 used for the discharge thin tube 2, wherein at least one of the open ends of the groove 12 of each disk 11, preferably the open end directed to the cathode 1 side. A discharge prevention metal piece 13 for reducing the cross-sectional area of the groove 12 when viewed from the axial direction is provided therein.

That is, the disk 11 as shown in FIG.
2 is inserted into the envelope 9 in the same manner as described with reference to FIG. 2, while maintaining the same conductance as the discharge capillary shown in FIG. Can be further reduced.

[0024]

As described above, the gas laser tube according to the present invention has a structure in which a discharge thin tube is stacked with a disk of several mm and inserted into a cylindrical envelope. On the side surface of the disk, a plurality of grooves having a width of several mm and a depth of several mm are provided evenly in the circumferential direction, and viewed from the axial direction so that at least a part of the grooves of each disk overlap. It is spirally arranged in a state.

In the discharge capillary having such a configuration, the number of disks is optimally set based on the required laser output and required light characteristics, thereby increasing the conductance of the gas return path and increasing the gas return path. Can prevent the occurrence of discharge. In addition, heat conduction can be enhanced, and damage to the laser tube is prevented. further,
A laser tube structure that is strong against external force can be provided. Therefore, it is possible to provide a gas laser tube capable of outputting a stable laser output for a long time.

[Brief description of the drawings]

FIG. 1 is a sectional view of a gas laser tube according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a configuration of a discharge capillary of the gas laser tube shown in FIG.

FIG. 3 is a schematic view showing a modified example of the discharge capillary shown in FIG. 2;

FIG. 4 is a sectional view of a disk of a discharge capillary according to another embodiment of the present invention.

FIG. 5 is a sectional view of a conventional gas laser tube.

FIG. 6 is a three-dimensional view of a conventional discharge capillary.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cathode, 2 ... Discharge capillary, 3 ... Anode, 4 ... Output mirror, 5 ... High reflection mirror, 6 ... Cathode envelope, 7 ... Metal ring, 8 ... radiation fin, 9 ... envelope, 10 ... discharge path, 11 ... disk, 12 ... gas return path, 13 ... discharge prevention metal piece.

Claims (4)

[Claims] A cathode, a discharge tube made of an insulator, an anode, a cylindrical envelope for enclosing gas, and an optical resonator constituted by a pair of mirrors sandwiching them; The gas discharge tube has a gas return path so as to surround the space for discharge, wherein the discharge tube has a cylindrical shape. A large number of insulating discs having a central through hole are provided in series, and at least one groove is provided on a side surface of each of the insulating discs along the tube axis direction. A gas laser tube which is arranged so as to partially overlap each other to form a non-linear gas return path. 2. The gas laser tube according to claim 1, wherein said groove provided on the side surface of each of said insulating disks has an opening area at an open end larger than near an axial center. . 3. The groove provided on a side surface of each of the insulating disks is configured such that an opening area is smaller at at least one open end than near the center in the axial direction. Item 3. A gas laser tube according to any one of Items 1 and 2. 4. The gas laser according to claim 3, wherein said groove is provided with a discharge preventing metal piece capable of making an opening area of said groove narrower than near an axial center. tube.