JPH07221380A - Method and device for oscillating gas laser - Google Patents

Abstract

PURPOSE:To perform highly efficient stable preliminary ionization by making the breakdown voltages of preliminary ionizing electrodes uniform by causing the preliminary ionization after weakly ionizing the prelintinary ionizing electrodes by projecting X rays or ultraviolet rays between each ionizing electrode. CONSTITUTION:A gas laser medium in the gap of each pin electrode pair 20 is weakly ionized when the medium is irradiated with X rays and, when the medium is weakly ionized, a trigger controller 26 outputs a main discharge triggering signal to a thyratron 17. As a result, the thyratron 17 is energized and electric charges accumulated in a main capacitor 16 move to each peaking capacitor 19, resulting in the charging of the capacitors 19. When the voltage across each pin electrode pair 20 reaches a prescribed value, the electrode pair 20 ntakes spark discharge and, as a result, ultraviolet rays are generated and the main discharging space of each main electrode 13 and 14 is preliminarily ionized. When the voltage between the main electrodes 13 and 14 reaches a prescribed high value, main discharge is generated between the electrodes 13 and 14 and, as a result, laser oscillation occurs and laser light is outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse-laser-excited gas laser oscillating device for generating a spark discharge in a preionization electrode for preionization and then generating a main discharge to oscillate a gas laser beam.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram of a gas laser oscillator employing the UV automatic preionization system. A main capacitor 2 and a thyratron 3 are connected in parallel to the laser high voltage power supply 1, and main electrodes 4 and 5 are connected to the main capacitor 2 among them. These main electrodes 4 and 5 are a gas laser medium,
For example, they are arranged to face each other in a laser chamber in which excimer gas is sealed.

A plurality of pin electrode pairs 7 as preionization electrodes are connected to the main electrodes 4 and 5 via a plurality of peaking capacitors 6. The peaking capacitor 6 and the pin electrode pair 7 are connected in parallel to the main electrodes 4 and 5 as shown in FIG. 5, and are arranged at predetermined intervals along the longitudinal direction of the main electrodes 4 and 5. There is.

When each pin electrode pair 7 is connected in parallel to each main electrode 4 and 5, each pin electrode pair 7 is connected to a peaking capacitor 8 via a plurality of ballast coils 9 as shown in FIG. It may be configured to be connected.

With such a configuration, the main capacitor 2 is charged from the laser high voltage power source 1. When the thyratron 3 is turned on in this state, the electric charge accumulated in the main capacitor 2 is transferred to each peaking capacitor 6 for charging, and when the voltage between each pin electrode pair 7 reaches a predetermined value, these pins are charged. Spark discharge is generated in the electrode pair 7.

UV light is generated by the spark discharge, and the main discharge space between the main electrodes 4 and 5 is preionized. Then, when the voltage between the main electrodes 4 and 5 reaches a predetermined high voltage, a main discharge occurs between the main electrodes 4 and 5.

Due to the occurrence of this main discharge, laser resonance occurs in a laser resonator (not shown), and gas laser light is output. However, the plurality of pin electrode pairs 7 do not fire at the same time because they have different breakdown voltages, but rather fire independently. FIG. 7 shows the measurement result of the laser breakdown voltage waveform between the main electrodes 4 and 5, and the spark discharge is generated randomly as shown in the spark discharge ignition period a.

There is an optimum time range between the spark discharge and the start of the main discharge, and there is a possibility that the spark discharge that is lately ignited may not sufficiently contribute to the preionization.

In addition, the spark discharge is slow and ignited,
The gas laser medium around the pin electrode pair 7 is ionized by the UV light of the spark discharge previously ignited, and the breakdown voltage is lowered. As a result, the intensity of UV light generated from each spark discharge may become non-uniform.

Further, apart from non-uniformity, when operated for a long time, the tip portions of each pin electrode pair 7 are worn, the life of the laser gas medium is shortened, the maintenance time is further increased, and the life of the apparatus is shortened. There is a problem of shortening.

[0011]

As described above, since the breakdown voltage of each pin electrode pair 7 is different, a spark discharge is generated randomly, and it does not sufficiently contribute to preionization, and the intensity of UV light is reduced. It becomes uneven. Also, each pin electrode pair 7
There is also the problem of tip wear.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a gas laser oscillation method and an apparatus therefor which can make the breakdown voltage of each preionization electrode uniform and perform efficient and stable preionization.

[0013]

According to a first aspect of the present invention, a spark discharge is generated in a plurality of preionization electrodes arranged in parallel with respect to each of the main electrodes arranged to face each other, and the main discharge space is preionized. Then, in a gas laser oscillation method in which a main discharge is generated between the main discharge electrodes to oscillate a laser beam, X-rays or ultraviolet rays are irradiated between the preliminary ionization electrodes to weakly ionize them, and then preliminary ionization is generated. The gas laser oscillation method is intended to achieve the above object.

According to a second aspect of the present invention, spark discharge is generated in a plurality of preionization electrodes arranged in parallel with respect to each of the main electrodes arranged to face each other, and the main discharge space is preionized. In a gas laser oscillator that oscillates a gas laser beam by generating a main discharge between them, an X-axis is formed between each preionization electrode.
X-ray or ultraviolet ray source for weakly ionizing the pre-ionization electrodes by irradiating them with ultraviolet rays or ultraviolet rays, and X-ray for generating X-rays or ultraviolet rays from the X-ray or ultraviolet ray source before spark discharge is generated in each pre-ionization electrode Or ultraviolet ray control means,
A gas laser oscillating device which has the above-mentioned object and is intended to achieve the above object.

According to the third aspect of the present invention, the respective main electrodes are arranged to face each other in the laser chamber in which the gas laser medium is sealed, a plurality of preionization electrodes are arranged along these main electrodes, and both end sides of each main electrode are arranged. In a gas laser oscillating device in which mirrors are respectively arranged to form a laser resonator, power is supplied to each main electrode and each preionization electrode to preionize the main discharge space between each main electrode, and then to the main electrode. A charging / discharging circuit for generating a discharge to cause a laser resonance in the laser resonator, an X-ray or ultraviolet ray source for weakly ionizing the preionization electrodes by irradiating X-rays or ultraviolet rays between the preionization electrodes, and An X-ray or ultraviolet ray is generated from an X-ray or ultraviolet ray source to weakly ionize between the pre-ionization electrodes, and thereafter trigger control means for controlling the operation of the charge / discharge circuit is provided to achieve the above object. It is a Sureza oscillation device.

According to the fourth aspect, the X-ray or ultraviolet ray source radiates the X-ray or ultraviolet ray through the mirrors of the laser resonator to irradiate between the respective preionization electrodes. Claim 5
According to the X-ray source, X-rays are emitted from the back surface of the main electrode between the respective preionization electrodes. According to claim 6, X
The X-ray or UV source can control the X-ray or UV generation amount.

[0017]

According to claim 1, the plurality of preionization electrodes are provided with X
Irradiation with rays or ultraviolet rays causes weak ionization, and then pre-ionization occurs. Then, a main discharge is generated between the main discharge electrodes to oscillate gas laser light. By weakly ionizing in this way, there is no time lag in the generation of the spark discharge of each preionization electrode, and the spark discharge is uniformly generated.

According to a second aspect of the present invention, by the control of the X-ray or ultraviolet ray control means, X-rays or ultraviolet rays are generated from the X-ray or ultraviolet ray source and applied to the plurality of preionization electrodes to weakly ionize them, and then each is ionized. The preionization electrode is spark-discharged to generate preionization. Then, a main discharge is generated between the main discharge electrodes to oscillate gas laser light.

According to the third aspect of the present invention, the trigger control means generates X-rays or ultraviolet rays from the X-ray or ultraviolet ray source to irradiate the plurality of preionization electrodes to weakly ionize them, and thereafter controls the operation of the charge / discharge circuit. Then, power is supplied to the preionization electrode to generate preionization, and further main discharge is generated between the main discharge electrodes to resonate the laser resonator and oscillate gas laser light.

In this case, according to the fourth aspect, the X-ray or ultraviolet ray source irradiates the X-ray or ultraviolet ray between the respective preionization electrodes through the mirror of the laser resonator. Further, according to claim 5, the X-ray source emits X-rays from the back surface of the main electrode between the respective preionization electrodes. Further, according to the sixth aspect, the X-ray or ultraviolet ray source can control the amount of X-ray or ultraviolet ray generation, and can control the preionization.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a gas laser oscillator employing the UV automatic preionization system. The laser high voltage power supply 10 is connected to a laser chamber 12 via a charging / discharging circuit 11.
The respective main electrodes 13 and 14 therein are connected.

The charging / discharging circuit 11 has a structure in which a main capacitor 16 and a thyratron 17 are connected to a laser high voltage power source 10 via a resistor 15. On the other hand, a gas laser medium such as excimer gas is sealed in the laser chamber 12, and the main electrodes 1 are blown by the fan 18.
It circulates between 3 and 14. This allows
A new gas laser medium is replaced between the main electrodes 13 and 14 for each oscillation of the pulse gas laser.

A plurality of pin electrode pairs 20 are provided between the main electrodes 13 and 14 via a plurality of peaking capacitors 19.
Are connected in parallel. And, these pin electrode pairs 20
Are arranged at predetermined intervals along the longitudinal direction of each of the main electrodes 13 and 14. A charging inductance 21 is connected between the main electrodes 13 and 14.

Further, on the extension of the respective main electrodes 13 and 14 in the laser chamber 12 in the longitudinal direction, respective mirrors 22 and 23 constituting a laser resonator are provided. One of the mirrors 22 and 23 is an output mirror, and the other mirror 23 is a high reflection mirror.

Of these, on the back side of the high reflection mirror 23,
An X-ray tube 24 as an X-ray source is arranged. The X-ray tube 24 generates X-rays by applying a high voltage from the X-ray high-voltage power supply 25, transmits the X-rays through the high-reflection mirror 23, and irradiates the gaps between the pin electrode pairs 20 with each other to weaken the X-rays. Ionize.

In this case, since the X-ray dose does not directly carry out the preionization, a much smaller dose than that in the case where the preionization is directly carried out by the X-ray is sufficient. The trigger control device 26 sends a trigger signal for X-ray generation to the high-voltage power supply 25 for X-rays to apply a high voltage to the X-ray tube 24, and after a predetermined period from the trigger signal generation, the thyratron of the charging / discharging circuit 11. It has a function of sending a trigger signal for generating a main discharge to 17.

Next, the operation of the device configured as described above will be described. The main capacitor 16 is charged through the resistor 15 from the laser high voltage power source 10.

In this state, the trigger control device 26 has the X
An X-ray generation trigger signal is sent to the high-voltage power supply 25 for lines. As a result, a high voltage is applied to the X-ray tube 24 from the X-ray high-voltage power supply 25, and X-rays are generated from the X-ray tube 24.

The X-rays are transmitted through the high-reflection mirror 23 which constitutes the laser resonator, and are radiated between the gaps between the pin electrode pairs 20 (the discharge space of the pin electrode pairs). This X-ray irradiation weakly ionizes the gas laser medium in the gap between each pin electrode pair 20.

After a lapse of a predetermined period from the irradiation of this X-ray, the trigger control device 26 sends a main discharge trigger signal to the thyratron 17 of the charge / discharge circuit 11.
Upon receiving this trigger signal, the thyratron 17 becomes conductive,
The electric charge accumulated in the main capacitor 16 is transferred to each peaking capacitor 19. As a result, each peaking capacitor 19 is charged, and when the voltage between each pin electrode pair 20 reaches a predetermined value, a spark discharge is generated in each pin electrode pair 20.

UV light is generated by the spark discharge, and the main discharge space between the main electrodes 13 and 14 is preionized. Then, when the voltage between the main electrodes 13 and 14 reaches a predetermined high voltage, main discharge occurs between the main electrodes 13 and 14.

As a result, laser resonance occurs in the laser resonator and laser light is output. Here, the X-ray tube 24
The time relationship between the application of a high voltage to the main discharge and the start of the main discharge will be described. As shown in FIG. 2, a spark discharge is generated in each pin electrode pair 20 after a predetermined period t has elapsed after the X-ray tube voltage Vx was applied. is doing. The spark discharge ignition period a.

At this time, the spark discharge does not vary as in the conventional spark discharge shown by the dotted line b, and is weakly ionized by the X-ray irradiation so that there is no time lag as shown by the solid line. Then, this spark discharge is uniformly generated at a breakdown voltage which is not so high.

In order to uniformly generate the spark discharge as described above, the predetermined period (delay time) t from the application of the high voltage to the X-ray tube 24 to the start of the main discharge becomes important. The predetermined time period t varies depending on the X-ray dose and its pulse width, but if the peak value of the X-ray tube voltage Vx is -40 kV and the pulse half width is 200 ns, the delay time t is 100 to 3.
00 ns is the optimum value.

Therefore, the trigger controller 26 delays the delay time t from when the X-ray dose from the X-ray tube 24 shows the peak value.
After (for example, 100 to 300 ns), the main discharge trigger signal is sent to the thyratron 17. This allows
Spark discharge is simultaneously and uniformly generated in each pin electrode pair 20.

As described above, in the above-described embodiment, the X-ray tube 24 irradiates the gap between the pin electrode pairs 20 with X-rays to cause weak ionization, and then preliminary ionization is generated to generate each main electrode 13, Since the main discharge is generated between 14 to oscillate the laser beam, there is no time lag in the spark discharge generation of each pin electrode pair 20, and the spark discharge can be simultaneously and uniformly generated in each pin electrode pair 20. .

As a result, the main discharge space between the main electrodes 13 and 14 can be uniformly preionized, and a uniform initial electron density distribution can be obtained both temporally and spatially. Therefore, the time between the spark discharge and the start of the main discharge can be set within an optimum time range, the spark discharge can sufficiently contribute to preionization, and the intensity of UV light generated from the spark discharge can be made uniform. .

As a result, stable main discharge can be generated, high efficiency of pulsed laser oscillation and high repetition rate are possible, and high performance can be achieved. Further, since the breakdown voltage of each pin electrode pair 20 is made uniform, the wear of the tip of each pin electrode pair 20 at the time of high breakdown voltage can be reduced, and along with this, the influence of dust is reduced and the length of the laser gas medium is reduced. The life can be increased, the maintenance can be further reduced, and the life of the device can be extended.

Further, since the X-rays are transmitted through the high-reflection mirror 23 constituting the laser resonator and applied to the gaps between the pin electrode pairs 20, the gaps can be uniformly and surely weakly ionized. In this case, even if the X-ray dose is extremely small, weak ionization can be sufficiently performed, so that weak ionization can be performed by a simple method of transmitting the light through the high reflection mirror 23.

The present invention is not limited to the above-mentioned embodiment but may be modified as follows. The X-ray tube 24 may be arranged so as to directly irradiate each pin electrode pair 20 with X-rays. For example, when irradiating each pin electrode pair 20 with X-rays, the X-ray tube 24 is moved to each main electrode 13, 14. X is generated from the X-ray tube 24 by arranging it on the back surface of one or both of the above and making a part of these main electrodes 13 and 14 thin.
A line may be applied to each pin electrode pair 20 through the thin portion from the back surface of the main electrode 13 or 14. Even with such a structure, the same effect as that of the above-described embodiment can be obtained.

Further, as shown in FIG. 3, a high voltage power source 25 for X-rays
The voltage control device 30 is connected to the X-ray high-voltage power supply 2
The voltage applied to the X-ray tube 24 from 5 may be variably controlled.

By variably controlling the voltage applied to the X-ray tube 24 in this manner, it becomes possible to control the UV preionization. For example, the X-ray dose is reduced with respect to the decrease in the preionization ability during high repetition laser oscillation. Can be dealt with.

Further, each pin electrode pair 20 has a peaking capacitor 8 for each main electrode 13, 14 as shown in FIG.
May be connected, and the ballast coils 9 may be connected via a plurality of ballast coils 9.

Although the apparatus using the X-ray tube as shown in FIG. 1 has been described so far, the same effect can be obtained by using an ultraviolet source such as a Xe lamp or a mercury lamp instead of the X-ray tube. However, when ultraviolet rays are used, the transmission characteristics are inferior to those of X-rays, so it is more efficient to install them inside the chamber. In this case, a pin electrode or the like is further installed between the preionization electrodes at a place where ultraviolet rays can be irradiated, and the preionization discharge is performed.

[0045]

As described above in detail, according to the present invention, it is possible to provide a gas laser oscillating method and an apparatus thereof which can make the breakdown voltage of each preionization electrode uniform and perform efficient and stable preionization.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a gas laser oscillator using a UV automatic preionization system according to the present invention.

FIG. 2 is a diagram showing a temporal relationship between an X-ray tube voltage and the start of main discharge.

FIG. 3 is a configuration diagram showing a modified example of the present invention.

FIG. 4 is a block diagram of a conventional device.

FIG. 5 is a diagram showing connection of pin electrode pairs.

FIG. 6 is a diagram showing connection of pin electrode pairs.

FIG. 7 is a diagram showing variations in spark discharge in a conventional device.

[Explanation of symbols]

10 ... High-voltage power source for laser, 11 ... Charge / discharge circuit, 12 ... Laser chamber, 13, 14 ... Main electrode, 17 ... Thyratron, 19 ... Peaking capacitor, 20 ... Pin electrode pair,
22, 23 ... Mirror, 24 ... X-ray tube, 25 ... High-voltage power source for X-ray, 26 ... Trigger control device.

Claims (6)

[Claims] 1. Main electrodes are arranged to face each other, and spark discharge is generated in a plurality of preionization electrodes arranged in parallel with respect to these main electrodes to preionize the main discharge space. In a gas laser oscillation method of generating a main discharge between them and oscillating a gas laser beam, X-rays or ultraviolet rays are radiated between the respective preionization electrodes to weakly ionize, and then the preionization is generated. Gas laser oscillation method. 2. The main electrodes are arranged so as to face each other, and a spark discharge is generated in a plurality of preionization electrodes arranged in parallel with respect to these main electrodes to preionize the main discharge space. In a gas laser oscillator for generating a main discharge between them and oscillating a gas laser beam, an X-ray or ultraviolet ray source for weakly ionizing between the preliminary ionization electrodes by irradiating the preliminary ionization electrodes with X-rays or ultraviolet rays, A gas laser oscillating device comprising: an X-ray or ultraviolet ray control means for generating X-rays or ultraviolet rays from the X-ray or ultraviolet ray source before generating a spark discharge at each preionization electrode. 3. Main electrodes are arranged opposite to each other in a laser chamber in which a gas laser medium is sealed, a plurality of preionization electrodes are arranged along these main electrodes, and mirrors are provided on both ends of each main electrode. In a gas laser oscillating device formed by arranging and forming a laser resonator, electric power is supplied to each of the main electrodes and each of the preionization electrodes to preionize a main discharge space between the main electrodes, and then main discharge is performed. A charging / discharging circuit for generating laser resonance in the laser resonator, and an X-ray or ultraviolet ray source for weakly ionizing between the preliminary ionization electrodes by irradiating the preliminary ionization electrodes with X-rays or ultraviolet rays, Trigger control means for generating X-rays or ultraviolet rays from this X-ray or ultraviolet ray source to weakly ionize between the preliminary ionization electrodes and thereafter control the operation of the charge / discharge circuit is provided. Gas laser oscillation device to be considered. 4. The gas laser oscillating device according to claim 3, wherein the X-ray or ultraviolet ray source irradiates the X-ray or ultraviolet ray through the mirror of the laser resonator between the respective preionization electrodes. 5. The gas laser oscillator according to claim 3, wherein the X-ray source irradiates X-rays from the back surface of the main electrode between the respective preionization electrodes. 6. The gas laser oscillator according to claim 3, wherein the X-ray or ultraviolet ray source can control the amount of X-ray or ultraviolet ray generation.