JPH0276281A - Pulse laser oscillator - Google Patents

Abstract

PURPOSE:To obtain a large output laser light by connecting a plurality of capacitors for supplying energy between main electrodes corresponding to each spark discharge gap and connecting at least one capacitor to the spark discharge gap in parallel. CONSTITUTION:A capacitor C2 and a capacitor C3 connected in series between main electrodes 1 and 2 which oppose each other are connected corresponding to a row 3 of each spark discharge gap and each capacitor C3 is connected to each spark discharge gap 3 in parallel. Thus, since voltage divided by a plurality of capacitors C1-C3 is applied to the spark discharge gap 3, the time for the spark discharge gap 3 to initiate discharge is delayed, thus approaching to the time when the main discharge is initiated. It maintains increase in preliminary ionization electron concentration and spacious uniformity and forms a glow discharge with a high injection limit power value, thus achieving a large output laser light.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a pulsed laser oscillation device with an improved electrode structure.

(Prior Art) In gas-mediated lasers, in order to obtain good laser emission, it is necessary to generate a spatially uniform discharge in the laser medium.
In pulsed laser oscillation devices that generate short-pulse laser beams such as O2 lasers and excimer lasers, the operating gas pressure is as high as several atmospheres, and it contains CO2 gas, which has strong electron adhesion properties, so the above-mentioned problems occur. The discharge is focused,
Easy to cause arcing. To prevent this, a common method is to perform preliminary ionization prior to main discharge.

FIG. 3 shows an example of the electrode structure and excitation power supply circuit of a conventional pulsed laser oscillation device.

That is, the discharge part a is arranged in the laser medium, the second main electrode 2 is arranged opposite to the first main electrode 1, and a plurality of spark discharges are formed on both sides of the bidirectional electrode in the direction perpendicular to the plane of the paper. Gap 3 is provided.

Further, a capacitor C2 is connected between the main electrodes 1 and 2 via a spark discharge gap 3. Roughly speaking, the floating capacitor C8 isometrically represents the capacitance required between the spark discharge gap 3. Further, a capacitor C1 and a switch S1 are connected to the discharge part a via a residual inductance Ld of the circuit, and one end of the capacitor C1 is connected to a high voltage power supply (not shown) via a resistor R, and the other end is connected to a high voltage power supply (not shown) via a resistor R. The end is grounded via an inductance L.

Further, optical resonators (not shown) are disposed at both ends of the main electrodes 1 and 2 in the longitudinal direction (in the direction perpendicular to the plane of the drawing).

The operation of the conventional pulsed laser oscillation device configured in this manner will be described below. That is, in the path of high voltage power supply-resistance R-capacitor C1-inductance L, capacitor C1
is charged.

Then, when switch S1 is closed, capacitor C1
A charged voltage is applied between the main electrodes 1 and 2. Further, a voltage divided by the capacitor C2 and the floating capacitor C8 is applied to the spark discharge gap 3. Since this floating capacitor C5 is very small compared to the capacitor C2, the voltage of the capacitor C1 is almost always applied to the spark discharge gap 3, so that a part of the spark discharge gap 3 is discharged. Thereafter, all the spark discharge gaps 3 are discharged within a certain period of time, and the ultraviolet rays generated by this spark discharge preliminarily ionize the laser gas between the opposing main electrodes 1.2.

When the spark discharge gap 3 is discharged in this way, the charge on the capacitor Cz is transferred to the capacitor C2. As the voltage of capacitor C2 increases, the voltage between main electrodes 1 and 2 increases, and when the voltage between main electrodes 1 and 2 reaches a certain value or more, glow discharge occurs between main electrodes 1 and 2. ignite.

The laser gas is excited by this glow discharge, and a laser beam is generated in a direction perpendicular to the paper surface by the action of an optical resonator (not shown).

(Problem to be Solved by the Invention) However, in the conventional pulsed laser oscillation device having the above configuration, there is a problem to be solved that the discharge start time of each of the plurality of spark discharge gaps is not uniform. was there.

This point will be explained based on FIG. 2, which shows temporal changes in the voltage applied between the main electrodes 1 and 2 and to the capacitor C2. That is, in the conventional pulsed laser oscillation device, when the voltage of the capacitor C1 is applied to the discharge part a, the floating capacitor C is the closest among the three rows of spark discharge gaps arranged.
8 is small or the electric field strength is large, the discharge starts (point A). Since the value of the floating capacitor CS between the spark discharge gaps 3 differs for each spark discharge gap, the point at which the discharge starts is not determined.

When the spark discharge gap 3 is discharged in this manner, current flows from the capacitor C1 to the discharge portion a, and the capacitor C2 is charged.

On the other hand, the discharge breakdown characteristic curve of spark discharge gap 3 is
As shown by the broken line in FIG. 2, all the spark discharge gaps 3 are discharged at the point where this broken line intersects the curve indicating the voltage between the main electrodes (point B). In this way, the time when all the spark discharge gaps 3 discharge is time TO after the time when some of the spark discharge gaps 3 first start discharging.

In addition, the main discharge between the main electrodes starts when the voltage between the main electrodes reaches a certain value (0 point), so the time from the start of pre-ionization to the start of the main discharge is different for each spark discharge gap. As shown in FIG. 2, the minimum value is T1 and the maximum value is To +Tt. In addition, this time is Cz
, Ld, and the frequency determined by the loop of C2.

As mentioned above, in the conventional pulsed laser oscillation device,
The interval between pre-ionization and main discharge becomes longer, and the electrons generated by pre-ionization are recombined and lost, which not only reduces the pre-ionized electron density at the start of main discharge, but also increases the discharge variation in each spark discharge gap. As a result, the number of pre-ionized electrons becomes spatially dense, so the glow discharge between the main electrodes 1 and 2 tends to contract, which limits the injected power and makes it impossible to obtain a high-output laser.

The present invention was proposed to eliminate the above-mentioned drawbacks, and its purpose is to increase the pre-ionized electron density and ensure spatial uniformity to form a glow discharge with a high injection limit power value, The object of the present invention is to provide a pulsed laser oscillation device that can obtain high-output laser light.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides pulsed laser oscillation for pre-ionizing the main discharge space between the main electrodes by arranging a spark discharge gap array near a pair of opposing main electrodes. In the apparatus, a plurality of energy supply capacitors are connected in series between main electrodes, corresponding to each of the spark discharge gaps, and at least one of the plurality of capacitors is connected to the spark discharge gap. are connected in parallel.

(Function) According to the pulsed laser oscillator of the present invention, since the voltage divided by the plurality of capacitors is applied to the spark discharge gap, the time at which the spark discharge gap starts discharging is delayed, and the main discharge start time is delayed. can be approached.

Furthermore, since the voltage applied to the spark discharge gap is stabilized by the action of the capacitor, variations in discharge between each spark discharge gap are reduced.

(Example) Hereinafter, an example of the present invention will be specifically described based on FIGS. 1 and 2. Incidentally, the same members as those of the conventional type shown in FIG. 3 are given the same reference numerals, and the description thereof will be omitted.

In this embodiment, as shown in FIG. 1, a capacitor C2 and a capacitor C3 are connected in series between the opposing main electrodes 1 and 2, corresponding to each of the three rows of spark discharge gaps. There is. Each capacitor C3 is also connected in parallel to each spark discharge gap 3.

The pulsed laser oscillation device of this embodiment having such a configuration operates as described below. That is, capacitor C1
is charged through the path of high voltage power supply, resistor R, capacitor C1, and inductance L.

Then, when the switch S1 is closed, the voltage charged in the capacitor C1 is added to the residual inductance Ld,
A high voltage is applied between the main electrodes.

Further, a voltage divided by the capacitor C2 and the capacitor C3 is applied to the spark discharge gap 3.

That is, as shown in FIG. 2, the voltage applied between the main electrodes 1 and 2 is the sum of the voltages of the capacitors C2 and C3, which is (VO2 + VC3).

On the other hand, the voltage applied to capacitor C3 becomes VO2. This voltage VC3 is applied to the spark discharge gap 3, but
Since the discharge breakdown characteristic curve of the spark discharge gap 3 is as shown by the broken line in the figure, all the spark discharge gaps 3 are discharged at the intersection of the two lines. As a result, the time from the preliminary ionization start time to the main discharge start time becomes T2.

In this way, according to this embodiment, the voltage applied to the spark discharge gap is stabilized by the action of the capacitor C3.
Dispersion in discharge between each spark discharge gap is reduced.

Also, the voltage applied to the discharge section is applied to the two capacitors C
2 and C3, the voltage applied to the spark discharge gap 3 becomes smaller, the time at which the spark discharge gap starts discharging becomes later, and the time interval from the main discharge start time can be shortened.

As a result, the electrons generated by pre-ionization can be prevented from being lost due to recombination, so the density of pre-ionized electrons can be increased, and the spatial distribution of the number of pre-ionized electrons can be made uniform. This makes it possible to form a glow discharge with a high injection limit power value, and to obtain a high-output laser beam.

*Other embodiments* The present invention is not limited to the embodiments described above, and the number of capacitors connected in series between the main electrodes may be plural, and at least one of the capacitors may be connected in series between the main electrodes. , may be connected in parallel with each corresponding spark discharge gap.

[Effects of the Invention] As described above, according to the present invention, a plurality of energy supply capacitors are connected in series between the main electrodes corresponding to each spark discharge gap, and one of the plurality of capacitors is ,
By simple means of connecting at least one capacitor in parallel to the spark discharge gap, an increase in the preionized electron density and a spatial homogeneity can be ensured to form a glow discharge with a high injection limit power value and a large A pulsed laser oscillation device that can obtain output laser light can be provided.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the pulsed laser oscillation device of the present invention, Fig. 2 is a diagram showing the discharge characteristics of the inventive and conventional pulsed laser oscillation devices, and Fig. 3 is a circuit diagram of a conventional pulsed laser oscillation device. It is a circuit diagram showing an example of an oscillation device. 1... First main electrode, 2... Second main electrode, 3...
・Spark discharge gap.

Claims (1)

[Claims] In a pulsed laser oscillation device that arranges a spark discharge gap array near a pair of opposing main electrodes and pre-ionizes a main discharge space between the main electrodes, a plurality of energy supply capacitors are connected to each of the spark discharge gaps. A pulsed laser oscillation device characterized in that, corresponding to the above, at least one capacitor among the plurality of capacitors is connected in series between the main electrodes and connected in parallel to the spark discharge gap.