JPH0661557A - Gas laser device - Google Patents

Abstract

PURPOSE:To raise the average laser output of a gas laser device in accordance with the pulse-repetition rate of the device. CONSTITUTION:The gas laser device is provided with a laser container 1 in which a gas laser medium is enclosed, air blowers 4 and 5 which circulate the gas laser medium in a prescribed direction in the container 1, a plurality of pairs of main electrodes 2 and 3 which are arranged in series a the direction intersecting the circulating direction of the gas laser medium, and timing control circuit which excites the gas laser medium in main discharging space sections 2a and 3a between each main electrode pair by making the main discharging space sections 2a and 3a to generate a main discharge by respectively applying high voltages between the main electrode pairs with a time lag. In addition, the gas laser device is also provided with preliminarily iozing pin electrodes 7a and 7b which are arranged besides the container 1 on the side to which the gas laser medium flows out from the sections 2a and 3a and preliminarily ionize the space sections 2a and 3a prior to the main discharge.

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 pulsating laser light.

[0002]

2. Description of the Related Art In a gas laser device for pulse-oscillating laser light, the number of repetitive pulses is increased in order to increase the average output of laser light. In order to obtain a stable laser output by increasing the number of repetitive pulses, the gas laser medium that has experienced the discharge should be changed before the next discharge is ignited in the main discharge space between the pair of main electrodes. It must be replaced with a new gas laser medium. For that purpose, the gas laser medium must be circulated at a high speed. However, since the power consumption of the blower increases in proportion to the cube of the flow rate of the gas laser medium, the running cost may increase significantly.

Therefore, by arranging a plurality of pairs of main electrodes in series in a laser vessel and alternately firing each main electrode,
A gas laser device has been proposed in which the number of pulse repetitions is increased to improve the output.

This structure has the advantage that the pulse repetition rate can be increased without increasing the speed of the gas laser medium. However, the discharge is ignited in the first main discharge space between one of the main electrodes,
When the laser light is generated, in the second main discharge space between the other main electrodes, there may be a gas laser medium that has undergone preionization for the next main discharge. Since the gas laser medium subjected to the pre-ionization has a temperature gradient and contains impurities, the laser light generated in the first main discharge space portion is oscillated and output through the second main discharge space portion. At this time, since the optical path of the laser light may be disturbed, the directivity and output may be lowered.

[0005]

As described above, a plurality of pairs of main electrodes are arranged in series, and a main discharge is alternately generated in each pair of main electrodes to increase the number of pulse repetitions so that the laser light is emitted. In order to improve the output of the gas laser medium that has undergone preionization in the main discharge space between the main electrodes where the main discharge is not ignited, the optical path of the laser light generated at that time is It was disturbed by the gas laser medium subjected to the pre-ionization, which sometimes caused a decrease in directivity and output.

The present invention has been made in view of the above circumstances. An object of the present invention is to increase the number of pulse repetitions by arranging a plurality of pairs of main electrodes in series to increase the number of pulse repetitions. It is an object of the present invention to provide a gas laser device capable of increasing the output of laser light.

[0007]

In order to solve the above-mentioned problems, the first invention is to provide a laser container in which a gas laser medium is enclosed, and a gas laser medium in a predetermined direction in the laser container. And a plurality of pairs of main electrodes arranged in series along a direction intersecting the circulation direction of the gas laser medium, and a high voltage is applied to the main electrodes of each pair at different timings. And excitation control means for generating a main discharge in the main discharge space between each pair of main electrodes to excite the gas laser medium in the main discharge space, and a gas laser medium from the main discharge space in each main electrode. And a preliminary ionization means for pre-ionizing the main discharge space portion prior to the main discharge of the main electrode.

According to a second aspect of the present invention, there is provided a laser container in which a gas laser medium is enclosed, a blowing means for circulating the gas laser medium in a predetermined direction in the laser container, and the gas laser medium. 2 arranged in series along the direction intersecting the circulation direction
By applying a high voltage to the main electrodes of the pair and the main electrodes of each pair at a predetermined cycle with a timing difference, a main discharge is generated in the main discharge space between the main electrodes of each pair, and the main discharge space Control means for exciting the gas laser medium and controlling the flow rate of the gas laser medium circulating in the laser vessel via the air blowing means, and a main discharge of the main electrodes arranged on both sides of each of the main electrodes. Prior to the pre-ionization means for pre-ionizing the main discharge space portion, the discharge width of the main discharge space portion is W, and one end of the discharge width of the gas laser medium from the inflow side to the inflow side. V is the velocity V of the gas laser medium, where L is the distance to the preionization means, T / 2 is the period in which a high voltage is applied to each main electrode, and V is the flow velocity of the gas laser medium.
Is set to (W + L) /1.5T <V <(L / T).

[0009]

According to the first aspect of the present invention, the preionization means is arranged laterally of the main discharge space on the side where the gas laser medium flows out. It does not flow into the discharge space and disturb the optical path of the laser light.

According to the second aspect of the invention, the main discharge can be ignited when the gas laser medium that has undergone preionization does not stay in either of the pair of main discharge spaces. The light output can be made proportional to the increase in the pulse repetition rate.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.

The gas laser apparatus shown in FIG. 1 comprises a laser container 1 in which a gas laser medium is enclosed. In this laser container 1, a circulation path 1a for the gas laser medium is defined and formed, and in the circulation path 1a, there are two pairs of first pairs.
The main electrode 2 and the second main electrode 3 are arranged in series along the width direction of the circulation path 1a as shown in FIG.

In the circulation path 1a, a first blower 4 and a second blower 5 are provided in a portion corresponding to the first main electrode 2 in the width direction and a portion corresponding to the second main electrode 3, respectively.
Also, as shown in FIG. 1, a pair of heat exchangers 6 for cooling the gas laser medium is arranged.

The gas laser medium circulated by the blowers 4 and 5 is circulated in the main discharge spaces 2a and 3a between the main electrodes 2 and 3, respectively. Each main discharge space 2a, 3
On the side of the main electrodes 2 and 3 on the side where the gas laser medium flows out from a, that is, on the downstream side, a plurality of pairs of upper pin electrodes 7a and lower pin electrodes 7b, which form a pair with their tips facing each other, are provided. The main electrodes 2 and 3 are provided at predetermined intervals along the longitudinal direction.

As shown in FIG. 2, the first main electrode 2 is connected to the first high voltage pulse power supply circuit 9 of the control device 8, and the second main electrode 2 is connected to the second high voltage pulse power supply circuit 9.
The main electrode 3 of is connected to the second high-voltage pulse power supply circuit 10. Each power supply circuit 9, 10 has a high voltage power supply 11 as shown in FIG. At the cathode of this high-voltage power supply 11, one of the first and second main electrodes 2 and 3 is the main capacitor 12
Connected through. A thyratron 13 and a charging coil 14 are connected in parallel to the high voltage power source 11.

The upper pin electrode 7a is connected to the high voltage power source 11 via a pair of peaking capacitors 15 and the main capacitor 12 provided in parallel.
The other of the first and second main electrodes 2 and 3 and the lower pin electrode 7b are connected to the anode of the high voltage power supply 11.

The thyratron 13 is for controlling the electric discharge charged in the main capacitor 12 by pulse discharge. When the thyratron 13 is ignited and turned on,
The charge charged in the main capacitor 12 is the pin electrode 7 of each set.
It is applied between a and 7b. As a result, spark discharge is generated between the pin electrodes 7a and 7b to charge the peaking capacitor 15.

Ultraviolet rays generated by the spark discharge between the pin electrodes 7a and 7b irradiate the main discharge spaces 2a and 3a between the main electrodes 2 and 3 to preionize these main discharge spaces. This preliminary ionization triggers each main electrode 2,
The main discharge rises during 3. This main discharge is performed by the charge charged in the peaking capacitor 15 or the charge flowing from the main capacitor 12. As a result, the gas laser medium in the main discharge spaces 2a and 3a is excited to generate laser light.

The first high voltage pulse power supply circuit 9 and the second
The high voltage pulse power supply circuit 10 is a timing control circuit 1
The drive control is alternately performed by 6. When the first high-voltage pulse power supply circuit 9 is driven, spark discharge is ignited between the pin electrodes 7a and 7b arranged on the side of the first main electrode 2, and then the main electrode 2 The main discharge is ignited and the gas laser medium in the first main discharge space 2a is discharge-excited. As a result, laser light is generated from the first discharge space 2a.

Similarly, the second high voltage pulse power supply circuit 10
Is driven, after spark discharge is ignited between the pin electrodes 7a and 7b arranged on the side of the second main electrode 3,
The main discharge is ignited by the main electrode 3 to discharge and excite the gas laser medium in the second main discharge space 3a. As a result, laser light is generated from the second discharge space portion 3a.

An output mirror 17 constituting an optical resonator is provided on one end face of the laser container 1, which is one end side of the first main electrode 2 arranged in series, and the second main electrode 3 is provided. A highly reflective mirror 18 is provided on the other end surface of the laser container 1 which is one end side of the laser container 1. Therefore, the first main discharge space 2a
The laser light generated in the second main discharge space 3a is amplified by the optical resonator and oscillated and output from the output mirror 17.

In the gas laser device having such a structure, the main discharge is alternately ignited in the first main discharge space 2a and the second main discharge space 3a by the drive signal from the timing control circuit 16. Then, laser light is generated. Pre-ionization in each of the discharge spaces 2a and 3a is a spark discharge between the upper pin electrode 7a and the lower pin electrode 7b, which is located on the downstream side of the discharge space, which is the outflow side of the gas laser medium. Done by the ultraviolet light generated by.

The upper pin electrode 7a and the lower pin electrode 7b
Are disposed on the downstream side of the respective discharge spaces 2a, 3a, so that the gas laser medium that has undergone preliminary ionization does not stay in the main discharge spaces 2a, 3a where the main discharge is ignited. . That is, a temperature gradient is not generated in the main discharge spaces 2a, 3a by the gas laser medium that has undergone preliminary ionization.

Therefore, when laser light is generated in either the first main discharge space portion 2a or the second main discharge space portion 3a, the laser light is generated in the other main discharge space portion. When passing, since the other main discharge space is not disturbed by the temperature gradient, the directivity of the laser light and the oscillation efficiency are not reduced.

FIG. 3 (a) shows the laser light output P ₁ pulse-oscillated from the first main discharge space 2a, and FIG. 3 (b) shows the pulse oscillation from the second main discharge space 3a. The output P _{2 of} the laser light thus generated is shown. The laser light generated in one of the discharge spaces 2a, 3a is oscillated and output from the output mirror 17 without deteriorating the directivity and the oscillation efficiency in the other discharge space. Therefore, the average output of the laser oscillation is (P ₁ + P ₂ ) as shown in FIG. That is, it increases in proportion to the number of repetitive pulses.

On the other hand, conventionally, since the preionization means is provided on the upstream side of the main discharge space portion, the laser light output from one main discharge space portion flows into the other main discharge space portion. When passing, the optical path is disturbed by the temperature gradient of the gas laser medium whose temperature has risen due to the preliminary ionization in the other main discharge space. Therefore, the average output of the laser oscillation is P ₃ which is smaller than (P ₁ + P ₂ ) as shown in FIG.
Will be.

FIG. 4B shows the relationship between the pulse repetition number f and the average output P. According to the present invention, (P ₁ +
Although the output of (P ₂ ) can be obtained, in the past, (P ₁ +
It shows that only the output of P ₃ smaller than P ₂ ) can be obtained. 5 to 8 show a second embodiment of the present invention. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the upper pin electrode 7a
Preliminary ionization means consisting of the lower pin electrode 7b and the lower pin electrode 7b is provided not only on the downstream side of the first main discharge space 2a and the second main discharge space 3a but also on the upstream side. That is, the preionization has the same configuration as the conventional one. However, the timing control circuit 16 not only controls the timing of driving the first high voltage pulse power supply circuit 9 and the second high voltage pulse power supply circuit 10, but also via the speed control unit 31 as shown in FIG. First blower 4 and second blower 5
And a gas relay that is circulated by each blower.
The speed of the medium is adjusted.

The speed control of the gas laser medium by the speed controller 31 is performed as follows. First, as shown in FIG. 7, the width dimension of the main discharge generated in the main discharge spaces 2a, 3a between the respective main electrodes 2, 3 is W. From the one end of this discharge width, which is the inflow side of the gas laser medium, The distances to the pin electrodes 7a and 7b located on the inflow side and the distances to the pin electrodes 7a and 7b located on the outflow side of the gas laser medium are L and
When the period T / 2 in which a high voltage is alternately applied to the first main electrode 2 and the second main electrode 3 is set to T / 2, the velocity V of the gas laser medium by each of the blowers 4 and 5 is (W + L). /1.5T<V<(L/T) (1) Formula is set.

When the velocity of the gas laser medium is set as in the above formula (1), before the gas laser medium preliminarily ionized by the pin electrodes 7a, 7b on the upstream side flows into the main discharge spaces 2a, 3a. In addition, the main discharge can be ignited in each of the main discharge spaces 2a and 3a, and when the gas laser medium that has undergone the preliminary ionization flows out from each of the main discharge spaces 2a and 3a, each of the main discharge spaces 2a. 3a, the next main discharge can be ignited.

FIG. 8 shows a time chart. V _{1 in} the figure
Indicates the first discharge space 2a, and V ₂ indicates the second discharge space 3a. First, in cycle 0, the discharge is ignited to the inflow side pin electrodes 7a and 7b of the first discharge space 2a, and the gas laser medium of speed V that has undergone preionization is shown by a straight line A in the figure. The first discharge space portion 2 at the cycle T
flows into a.

On the other hand, at the period T / 2, the second discharge space 3a
A discharge is ignited on the inflow side pin electrodes 7a, 7b, and the gas laser medium of speed V subjected to pre-ionization there is a second discharge space 3a with a period of 1.5 T as shown by a straight line B in the figure. Flow into.

Therefore, when the gas laser medium indicated by the straight line A flows into the first discharge space 2a indicated by the point a ₁ on the straight line A, the main discharge is generated in the first discharge space 2a at the time T. When ignited, the gas laser medium indicated by the line B does not flow into the second discharge space 3a. Therefore, the first
From the discharge space portion 2a, laser light that is not subject to optical disturbance such as temperature gradient in the second discharge space portion 3a is oscillated and output.

Straight line B, which has undergone preionization at period T / 2
At the time of a period of 1.5 T in which the gas laser medium of No. 2 flows into the second discharge space portion 3a indicated by b on the same straight line, the gas laser medium undergoes preliminary ionization on the upstream side of the first discharge space portion 2a indicated by the straight line A. The gas laser medium passes through the first discharge space 2a as indicated by the point a on the straight line A. Therefore, if the main discharge is ignited in the second discharge space 3a at the time of b to generate laser light, the laser light is affected by the temperature gradient in the first discharge space 2a. It is possible to oscillate and output in a stable state without being affected by disturbed optical effects.

Further, in the cycle T, as shown by the straight line C, the first
The gas laser medium is preionized by the pin electrodes 7a and 7b on the inflow side of the discharge space 2a. Gas line of the straight line C
The medium is located at a position indicated by a point c ′ when the main discharge is ignited in the second discharge space 3a having a period of 1.5 T, which is indicated by b in the straight line B, and is located in the first discharge space 2a. Since it does not flow in, it does not adversely affect the laser light generated at 1.5 T in the second discharge space 3a.

The gas laser medium of the straight line C flows into the first discharge space 2a, and at the period 2T of the point c at which the main discharge is ignited in the first discharge space 2a, the straight line D is generated. Since the gas laser medium that has undergone pre-ionization on the upstream side of the second discharge space portion 3a at the time of the period of 1.5 T does not flow into the second discharge space portion 3a, the first discharge space portion 2a The laser light oscillated and output from the second discharge space 3a is not subject to optical disturbance.

That is, by setting the flow rate of the gas laser medium according to the above equation (1), the gas laser medium that has undergone preliminary ionization on the upstream side of one of the pair of main discharge spaces 2a, 3a is From the condition of [V <(L / T)], one of the main discharge spaces does not enter, or [V
From the condition of> (W + L) /1.5T], the main discharge can be ignited in the other main discharge space while flowing out from the one main discharge space. Therefore, when the main discharge is ignited in one of the main discharge spaces and laser light is oscillated and output, the laser light is optically disturbed in the other main discharge space and is output by hand. Since no reduction is caused, it is possible to obtain laser light whose output is proportional to the number of pulse repetitions.

[0038]

As described above, the first invention is a gas laser apparatus in which a plurality of pairs of main electrodes are arranged in series,
Preliminary ionization means is provided on the side of the main laser discharge space where the gas laser medium flows out.

A second invention is a gas laser device having two main discharge spaces in which two pairs of main electrodes are arranged in series, and one main discharge space has a gas laser medium inflow side. In the state where the gas laser medium that has undergone preliminary ionization in the main discharge space does not enter the main discharge space or flows out from the main discharge space, the main discharge is ignited in the other main discharge space and the laser light is emitted. Was generated.

Therefore, according to the present invention, when laser light is oscillated and output from one main discharge space, the other main discharge space undergoes preionization, and a gas laser medium having a temperature gradient is obtained. Does not stay, the laser light is output in a stable state without being subjected to thermo-optical disturbance. That is, if the number of laser oscillation pulses is increased,
The average output can be increased as the number of pulses increases.

[Brief description of drawings]

FIG. 1 is a sectional view of a gas laser device showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

3 (a) to 3 (c) are explanatory views of pulse laser output.

FIG. 4A is an explanatory view of a conventional pulse laser output,
(B) is an explanatory view comparing the output of the present invention with the output of the related art.

FIG. 5 is a sectional view of a gas laser device showing a second embodiment of the present invention.

FIG. 6 is a sectional view taken along line YY of FIG.

FIG. 7 is an explanatory view of the positional relationship between the main electrode and the preliminary ionization pin electrode.

FIG. 8 is a time chart illustrating the timing when the gas laser medium flows into the pair of main discharge spaces.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laser container, 2 ... 3 Main electrode, 2a, 3a ... Main discharge space part, 4, 5 ... Blower, 7a, 7b ... Pin electrode (pre-ionization means), 16 ... Timing control circuit (control means) ,
31 ... Speed control unit (control means).

Claims (2)

[Claims] 1. A laser container in which a gas laser medium is enclosed, a blowing means for circulating the gas laser medium in a predetermined direction in the laser container, and a circulation direction of the gas laser medium. The main discharge is generated in the main discharge space between the main electrodes of each pair by shifting the timing to the main electrodes of each pair and applying a high voltage to the main electrodes of each pair. Excitation control means for exciting the gas laser medium in the main discharge space, and the main discharge of the main electrodes disposed on the side where the gas laser medium flows out from the main discharge space of each of the main electrodes. A gas laser device comprising a preliminary ionization means for preliminary ionization of the main discharge space. 2. A laser container in which a gas laser medium is enclosed, a blowing means for circulating the gas laser medium in a predetermined direction inside the laser container, and a circulation direction of the gas laser medium. The main discharge space between the main electrodes of each pair is applied by applying a high voltage to the main electrodes of each pair in series with two pairs of main electrodes arranged in series along the direction of A gas laser that generates a main discharge, excites a gas laser medium in the main discharge space, and circulates in the laser container.
And a control means for controlling the flow velocity of the medium via the blower means, and a preionization means arranged on both sides of each main electrode for preionizing the main discharge space prior to main discharge of the main electrode. Then, the discharge width of the main discharge space is W, the distance from one end of the discharge width on the gas laser medium inflow side to the preionization means on the inflow side is L, and a high voltage is applied to each main electrode. Assuming that the cycle is T / 2 and the flow rate of the gas laser medium is V, the velocity V of the gas laser medium is set to (W + L) /1.5T <V <(L / T). Characterized gas laser device.