JPH0661558A - Gas laser device - Google Patents

Abstract

PURPOSE:To increase the laser output of a gas laser device by raising the pulse-repetition frequency of the device. CONSTITUTION:The gas laser device is provided with a laser container 1 in which a gas laser medium is enclosed, a pair of main electrodes 2 provided in the container 1, air blower which is provided in the container 1 and circulates the gas laser medium in a main discharging space section 13 between the electrodes 2, and a plurality of sets of preliminarily ionizing pin electrodes 3a and 3b positioned at a prescribed interval in the section 13 along one side in the longitudinal direction of the main electrodes 2 which becomes the flowing-in side of the gas laser medium. The electrodes 3a and 3b are so arranged that the distance between the electrodes 3a and 3b and main electrodes 2 is the maximum in the center of the electrodes 2 in their longitudinal direction and becomes shorter toward both ends of the electrodes 2.

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 for preionizing a main discharge space with a preionization pin electrode prior to main discharge between main electrodes.

[0002]

2. Description of the Related Art In a gas laser device, it is required to oscillate and output a laser beam with high repetition and high output.
Therefore, various improvements have been made.

FIG. 3 shows a gas laser device having a general structure. In the figure, 1 is a laser container in which a gas laser medium is enclosed. A circulation path 1a for a gas laser medium is defined in the laser container 1, and a pair of main electrodes 2 are arranged to face each other in the circulation path 1a. These main electrodes 2
An upper preliminary ionization pin electrode 3a and a lower preliminary ionization pin electrode 3b whose tips are spaced apart from each other and opposed to each other are arranged at predetermined intervals in the longitudinal direction of the main electrode 2 on both sides in the longitudinal direction.

The one main electrode 2 is connected to the cathode side of the high voltage power source 8 via the main capacitor 7, and the upper preionization pin electrode 3a is connected to the high voltage power source 8 via the peaking capacitor 9 and the main capacitor 7. Is connected to the cathode side of. The other main electrode 2 and the lower preliminary ionization pin electrode 3b are connected to the anode side of the high voltage power source 8.

A thyratron 11 and a charging coil 12 are connected in parallel to the high voltage power source 8. The thyratron 11 is for pulse discharge control of the electric charge charged in the main capacitor 7. When the thyratron 11 is ignited and turned on, the electric charge charged in the main capacitor 7 is transferred to the pin electrodes 3a of each set, Applied between 3b. As a result, spark discharge is generated between the pin electrodes 3a and 3b, and the peaking capacitor 9 is charged.

The ultraviolet rays generated by the spark discharge between the preionization pin electrodes 3a and 3b irradiate the main discharge space 13 between the pair of main electrodes 2 and preionize the main discharge space 13. This preliminary ionization triggers a main discharge between the pair of main electrodes 2. This main discharge is performed by the charge charged in the peaking capacitor 9 or the charge flowing from the main capacitor 7. This excites the gas laser medium in the main discharge space 13 to generate laser light.

A blower 14 for circulating the gas laser medium in the direction of the arrow in the circulation path 1a in the laser vessel 1.
A heat exchanger 15 for cooling the gas laser medium circulated by the blower 14 is provided. That is, the heat exchanger 15 is adapted to cool the gas laser medium which is excited by the discharge of the main electrode 2 and whose temperature has risen.

FIG. 4 shows the arrangement of the preliminary ionization pin electrodes 3a and 3b in the conventional gas laser device. That is, the main electrode 2 is arranged with its longitudinal direction substantially orthogonal to the flow direction of the gas laser medium shown by the arrow in the figure, and the preionization pin electrodes 3 a and 3 b are arranged on both sides of the main electrode 2 in the longitudinal direction. Are arranged in a straight line in a line at a predetermined interval.

In the figure, 16 is a pair of reflection mirrors forming an optical resonator provided at portions of the laser container 1 opposed to both longitudinal ends of the main electrode 2, and 17 is a space between the main electrodes 2. A pair of first guide bodies that guide the gas laser medium flowing into the main discharge space portion 13 and a pair of second guide bodies 18 that guide the gas laser medium flowing out of the main discharge space portion 13.

The high temperature gas laser medium which has undergone pre-ionization at the pre-ionization pin electrodes 3a, 3b arranged on the inflow side of the main discharge space 13 flows into the main discharge space 13 shown by hatching in FIG. Before, during inflow, and after outflow, the distribution states shown by the curves A to E in FIG. That is,
The distribution state of the gas laser medium in the width direction of the circulation path 1a in the laser container 1 of the gas laser medium that has just undergone preionization at the inflow side preionization pin electrodes 3a and 3b shown by the curve A is substantially linear. However, as it goes from the main discharge space portion 13 toward the outflow side toward the preliminary ionization pin electrodes 3a and 3b, as shown by the curves B to D, the central portion in the width direction has a higher flow velocity than both end portions.

Therefore, the pre-ionization pin electrode 3 on the inflow side is provided.
When passing through the main discharge space 13, the hot gas laser medium that has undergone preliminary ionization in a and 3b passes in a non-uniform distribution state in which the central portion passes first and both end portions lag, as shown by the curve C. To do. That is, the main discharge space portion 1
In No. 3, a high temperature gas laser medium that has undergone preliminary ionization and a low temperature gas laser medium that has not undergone preliminary ionization pass at the same time.

The gas laser medium having a high temperature has a lower discharge starting voltage than the gas laser medium having a low temperature. Therefore, if the main discharge is ignited in a state where the temperature distribution of the gas laser medium in the main discharge space 13 is nonuniform, it is difficult to uniformly ignite the main discharge between the main electrodes 2. Thereby,
Since the excitation efficiency of the gas laser medium decreases, the laser light cannot be oscillated at high output even if the repetition pulse frequency is increased.

FIG. 5 shows a conventional gas laser device,
The result of measuring the relationship between the laser output and the rotation speed of the blower 14 (speed of the gas laser medium) is shown. In the figure, f1 to f3
Indicates the pulse repetition frequency, and (f1 <f2 <f3
) Relationship.

As can be seen from this figure, when the repetition frequency is increased from f1 to f2 and f3, the blower 1
It was confirmed that the output decreased in the wide range of the rotation speed of 4 from a _{1 to} a ₂ .

In order to eliminate the influence of the high temperature gas laser medium that has undergone pre-ionization and to oscillate a high-power laser beam, the gas laser medium that has undergone pre-ionization passes through the main discharge space 13 and then becomes main. It suffices to ignite the discharge.
However, in that case, the pulse repetition rate cannot be increased unless the flow velocity of the gas laser medium is made sufficiently high, so there is a limit.

[0016]

As described above, conventionally, when the pulse repetition frequency is increased to oscillate a high-power laser beam, a high temperature gas laser that has undergone preliminary ionization is generated in the main discharge space. Since the medium and the low-temperature gas laser medium exist in a mixed state, the discharge starting voltage becomes nonuniform, and the discharge cannot be uniformly ignited. Therefore, even if the pulse repetition frequency is increased, the laser output may not be increased.

The present invention has been made based on the above circumstances. An object of the present invention is to make a hot gas laser medium having a high temperature, which has undergone preionization, uniformly flow into the main discharge space to obtain a high output. An object of the present invention is to provide a gas laser device capable of oscillating laser light.

[0018]

To solve the above problems, the present invention provides a laser container in which a gas laser medium is enclosed, a pair of main electrodes provided in the laser container, and a gas laser container provided in the gas laser container. A blower means for circulating the gas laser medium in the main discharge space between the pair of main electrodes, and a predetermined interval along one longitudinal direction of the main electrode which is the inflow side of the gas laser medium in the main discharge space. And a plurality of sets of preionization pin electrodes arranged in the above, wherein the preionization pin electrode has a maximum distance from the main electrode in the central portion in the longitudinal direction of the main electrode and becomes closer to both ends. It is characterized by being arranged as follows.

[0019]

According to the above construction, the gas laser medium which has undergone pre-ionization and has a high temperature can generate a main discharge space between the main electrodes even if the flow velocity of the gas laser medium in the longitudinal direction of the main electrode is different. Since it passes in a short time in a state substantially parallel to the long direction, the main discharge can be ignited in a stable state even if the pulse repetition frequency is increased.

[0020]

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 FIG.

In the gas laser device of the present invention, the arrangement state of the preliminary ionization pin electrodes 3a and 3b on the inflow side of the main discharge space 13 into which the gas laser medium flows is different from the conventional state. That is, a plurality of sets of preionization pin electrodes 3 on the inflow side
The distances a and 3b from the main electrode 2 are set to be the maximum in the central portion of the main electrode 2 in the longitudinal direction, and the a and 3b are arranged so as to become gradually closer to both ends. In this embodiment, the plurality of sets of preionization pin electrodes 3a and 3b are arranged in an arc shape which is convex in the direction in which the gas laser medium flows. The plurality of sets of pre-ionization pin electrodes 3a and 3b on the outflow side are linearly arranged.

According to the gas laser device having such a structure, the gas laser medium that has undergone preionization at the inflow side preionization pin electrodes 3a, 3b is the preionization pin electrode 3 described above.
By flowing from a and 3b to the main discharge space portion 13, the distribution state thereof changes from a convex state in the inflow direction of the gas laser medium indicated by the curve X to a substantially linear state indicated by the curve Y. In other words, the distribution state of the gas laser medium that has undergone preliminary ionization is changed from the curve X to the curve Y because the flow path resistance of the portion corresponding to the central portion in the longitudinal direction of the main electrode 2 in the circulation path 1a is smaller than that at both end portions. It becomes a state.

The high temperature gas laser medium that has undergone preliminary ionization passes through the main discharge space 13 in the state of the curve Y, so that the gas laser medium can pass through the main discharge space 13 in a short time. Then, the gas laser medium that has passed through the main discharge space 13 flows in a mountain-shaped distribution state as shown by curves Z and Z ′ in the figure.

As described above, if the time during which the high temperature gas laser medium that has undergone pre-ionization passes through the main discharge space 13 is shortened, the time during which the main discharge becomes non-uniform in the main discharge space 13 is shortened. It Therefore, even when the pulse repetition frequency is increased, the main discharge can be ignited in a stable state. That is, it becomes possible to oscillate high-power laser light by increasing the repetition frequency.

Similar to FIG. 5, FIG. 2 shows the relationship between the rotational speed of the blower 14 and the laser output when the pulse repetition frequency is changed within the range of f1 to f3. As can be seen from the figure, the output was reduced in a narrow range of the blower 14 rotation speed around a ₄ , but there was almost no reduction in the output in a region where the rotation speed was lower than that and including a _3. confirmed.

In the above embodiment, the preionization pin electrodes 3a, 3b on the inflow side of the gas laser medium are arranged in an arc shape. However, by the guide bodies provided on the inflow side and the outflow side of the main discharge space 13, The arrangement state may be changed according to the flow velocity distribution state of the gas laser medium in the width direction of the circulation path 1a. That is, the preionization pin electrodes 3a and 3b may be arranged so that the distribution state of the gas laser medium that has undergone preionization becomes linear and flows into the main discharge space 13.

Further, the preionization pin electrodes 3a and 3b may be provided at least on one side in the longitudinal direction of the main electrode, which is the inflow side of the gas laser medium, and are not necessarily provided on both sides.

[0028]

As described above, according to the present invention, a plurality of sets of preionization electrodes provided on one side in the longitudinal direction of the main electrode, which is the inflow side of the gas laser medium, are provided in the central portion in the longitudinal direction of the main electrode. The distance from the main electrode is the maximum, and the distance is closer to both ends.

Therefore, the gas laser medium that has undergone preliminary ionization is caused to flow into the main discharge space between the pair of main electrodes in a substantially linear distribution state, and the time during which the gas laser medium stays in the main discharge space can be shortened. Therefore, it is possible to increase the pulse repetition frequency of the main discharge in a stable state and increase the laser output.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an arrangement state of preionization pin electrodes of a gas laser device according to an embodiment of the present invention.

FIG. 2 is a graph of the relationship between the blower rotation speed and the laser output, similarly using the pulse repetition frequency as a parameter.

FIG. 3 is a configuration diagram of a general gas laser device.

FIG. 4 is an explanatory view showing an arrangement state of a preliminary ionization pin electrode of a conventional gas laser device.

FIG. 5 is a graph showing the relationship between the rotation speed of the blower and the laser output, similarly using the pulse repetition frequency as a parameter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laser container, 2 ... Main electrode, 3a, 3b ... Pre-ionization pin electrode, 13 ... Main discharge space part, 14 ... Blower.

Claims (1)

[Claims] 1. A laser container in which a gas laser medium is sealed, a pair of main electrodes provided in the laser container, and a main discharge space between the pair of main electrodes provided in the gas laser container. A blower means for circulating the medium, and a plurality of sets of preionization pin electrodes arranged at predetermined intervals along one side in the longitudinal direction of the main electrode on the inflow side of the gas laser medium in the main discharge space. The preionization pin electrode has a maximum distance from the main electrode in the central portion in the longitudinal direction of the main electrode, and is arranged so as to be closer to both ends as the distance is closer.