JPH02248092A - Discharge excitation type short pulse laser device - Google Patents

Abstract

PURPOSE:To obtain a stable glow current, to make laser gas long in service life, and to improve laser oscillation in efficiency by a method wherein an auxiliary electrode is provided between primary electrodes arranged opposed to each other, and electrons are increased in scattering number through the auxiliary electrode. CONSTITUTION:A switch is turned in an ON-state, the voltages between an opening electrode 9 and a primary electrode 8, and the opening electrode 9 and an auxiliary electrode 20 increase rapidly with the fast movement of charges. At this point, as the starting voltages of the auxiliary electrodes 11 and 20 are lower than that of primary discharge, an auxiliary discharge occurs at first on the surface of a dielectric 10 inside an opening provided to the opening electrode 9 and then also between the opening electrode 9 and the auxiliary electrode 20. A part of electrons induced by the auxiliary discharge and other electrons generated through photoionization by ultraviolet rays emitted from the discharge field serve as a seed which enables a primary discharge to be a uniform glow discharge, and then a primary discharge takes place in pulse in a primary discharge space 17 to make laser medium excited, in result laser rays are taken outside.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to discharge-excited short pulse lasers among gas lasers, and particularly relates to the improvement of preliminary excitation of the electric charge part thereof. be.

[Conventional technology]

The eighth factor is a cross-sectional view showing a conventional discharge-excited short pulse laser device. In the figure, (1) is a high voltage power supply, (2)
, (5) and (7) are capacitors, (3) is a high resistance, (4) an H switch, (6) is a coil, and (8) is placed in the laser gas flow, with the laser optical axis direction being the long plane direction. The first main electrode, (9) is the first main t! The apertures XtV and αQ formed by the second main electrode having a plurality of apertures are disposed opposite to the electrode (8) and are disposed so that the apertures are in close contact with the back surface of the pole (9). The dielectric (6) is disposed in close contact with this dielectric αO, and is the first auxiliary v facing the opening tFM (9).
L pole, (2) is the heat exchanger, (Ll is the fluid guide, α4 is the fan, α0 is the laser housing, α・ is the insulator, αη is the main discharge space, (G) is the arrow indicating the direction of the laser gas flow ,αI
is a metal base on which the first main pole (8) is entirely mounted.

Next, the operation will be explained. First, we will discuss the circuit system. Charge supplied from a high voltage power supply (1) is stored in a capacitor (2). Next, when the switch (4) becomes conductive, a connection is made from the capacitor (2) to the switch (4) and then to the capacitor (5) and the coil/coil via the ground line.
Due to the current loop that returns to the capacitor (2) through l'(6)t-, the specific charge stored in the capacitor (2) is transferred to the capacitor (5)K. Along with this rapid charge transfer, the opening is formed between the pole (9) and the first main electrode (8).
) and between the opening 1i (9) and the first auxiliary wLWiαυ
The voltage between the two rises rapidly. At this time, since the starting voltage of the auxiliary discharge is lower than the starting voltage of the main discharge, first, the mx body Q
Auxiliary discharge occurs on the Q surface. A part of the electrons generated in this auxiliary discharge and the electrons generated by photoionization with ultraviolet light from this discharge field become the seeds for making the main discharge a glow-like uniform discharge, and then the main discharge In the space αη, a main discharge occurs in a pulsed manner to excite the laser medium, and as a result, laser light is extracted. That is, as shown in FIG.
The first main electrode (8) and the discharge width of the aperture [1i (9)] Since the width of the aperture electrode (9) and the first auxiliary electrode (b) are short, if voltage is applied at the same time, a discharge will occur. Discharge begins first between the latter, which has a shorter width.

In this case, corona discharge occurs, and ultraviolet rays are emitted at the same time as this discharge. Note that corona discharge is a discharge that stops before transitioning to arc discharge, and like arc discharge, it emits ultraviolet rays.

Next, the ultraviolet light dissociates trace gas molecules in the atmosphere and generates electrons. Since ultraviolet rays are light, the first main electrode (8
) and the opening ff1 (9), and as a result, electrons are naturally generated in the entire space. Then, the generated electrons are acted upon by a strong electric field and move one after another to the opening 1i (9) side, and as the ionization action is repeated along with this movement, the entire main discharge space αη is filled with all the electrons. At this time, glow discharge that contributes to laser oscillation is established. Note that, of course, + ions also remain in the discharge field, but due to their large mass, the mean free path is
, can hardly move.

Next, we will discuss the fluid system. Generally, after a main discharge occurs in a pulsed manner, the main discharge space α25 is in a non-uniform state both thermally and in terms of charge distribution, so that the next pulsed main discharge is likely to become an arc. For this reason, it is necessary to replace the laser gas tube in the main discharge space aη before the next pulse main discharge occurs, so it is necessary to replace the laser gas tube in the main discharge space aη. An exchanger (6) is provided.

[Problem to be solved by the invention]

Since the conventional discharge-excited short pulse laser device is configured as described above, an auxiliary discharge is generated on the surface of the dielectric (G) only by the aperture provided in the aperture electrode (9). Due to the discharge, it is not possible to obtain sufficient electrons to make the main discharge a glow-like uniform discharge, and the main discharge shifts to an arc discharge that does not contribute to laser oscillation. Therefore, there are problems in that the arc discharge causes deterioration of the laser gas and a decrease in laser oscillation efficiency.

This invention was made to solve the above-mentioned problems, and an object of the present invention is to obtain a discharge-excited short-pulse laser device capable of prolonging the life of the laser gas and improving laser oscillation efficiency. purpose.

[Means for solving problems]

A discharge-excited short pulse laser device according to the present invention includes a first main electrode provided on a metal paste, and a plurality of openings v.
i-, a second main electrode disposed opposite to the first main electrode, a dielectric provided in close contact with the back surface of the second main electrode, and a dielectric provided in close contact with the dielectric. a first auxiliary electrode facing the second main electrode, the surface of which is covered with a dielectric, one side of which is in contact with the second main electrode and the dielectric;
The other is provided with a second auxiliary electrode fixed to the metal base.

[Function] In this invention, by applying a high voltage, the second
At the same time, an auxiliary discharge is generated on the dielectric surface in the opening of the main electrode, and at the same time, auxiliary discharge is also generated in the 20th main electrode and the second auxiliary electrode, and electrons caused by ultraviolet rays are puffed into the main discharge space.

[Funny example of invention]

Hereinafter, Example t-1 of this invention will be described. FIG. 1 is an enlarged side sectional view of the electrode portion of the device according to the present invention, and FIG. 2 is a front sectional view.

In each figure, 4 is a second auxiliary electrode whose surface is covered with a dielectric, and one end is an open-hole electrode (9) that is the second main electrode.
and the dielectric αQ, and the other end is in contact with the first main chamber fM
The metal bases α, which are at the same potential as (8), are very firmly fixed and are arranged at predetermined intervals in the direction of the laser optical axis. Note that the configuration other than this second auxiliary electrode (1) is the same as the conventional one, so the explanation will be omitted.

Next, the movement will be explained. As stated in the prior art,
When the switch (4) becomes conductive, charges move rapidly and the gap between the aperture electrode (9) and the first main chamber Wi (8) and between the aperture electrode (9) and the first auxiliary electrode ( 6), Open-hole electrode (
9) and the second auxiliary voltage FM (e) rises sharply. At this time, the first and second auxiliary electric FMs (b).

Since the starting voltage of (1) is lower than the starting voltage of the main discharge, an auxiliary discharge occurs on the surface of the dielectric GO at the secondary hole provided in the hole electrode 11 (9), and at the same time, at the same time,
9) and the second auxiliary voltage f1gO.

A part of the electrons generated in this auxiliary discharge and electrons generated by photoionization by ultraviolet light from this discharge field become seeds for making the main discharge into a glow-like uniform discharge, and then in the main discharge space αη. A main discharge occurs in a pulsed manner to excite the laser medium, and as a result, laser light is extracted.

By the way, in order to maintain the glow discharge at the end of the discharge, the discharge formation at the initial stage of the glow discharge plays an important role. At the end of the discharge, the supply of current decreases, and the discharge path is concentrated in the place where it is most likely to fly. Then, when the discharge is concentrated, it becomes a di-plasma state with high electron density and positive ion density, and shifts to a-d discharge. This is called after-arc. Naturally, this arc discharge does not contribute to laser excitation, and worse, it decomposes the laser gas and causes gas deterioration. In order to eliminate this after-arc phenomenon, increase the electron density for the first preliminary excitation. ■Aim to equalize electron density.

It is necessary to take countermeasures for this, but first, in order to increase the electron density in (2), there are several methods such as increasing the capacitance of the dielectric electrode or increasing the starting voltage of the discharge voltage. In order to make the electron density uniform (2), there is a method of scattering electrons into the main discharge space αη by using the apertured electrode (9) as described above. However, in any case,
It is clear that eliminating the after-arc phenomenon contributes to improving the laser total loss efficiency and extending the life of the laser gas, so it is necessary to perform preliminary excitation in consideration of the above.

Therefore, in the present invention, as described above, the first auxiliary power F
M(6), dielectric material QO and aperture tFM(9), aperture 1ac & (9) and second
In addition to the capacitor formed by the auxiliary electrode (1), the energy Jjk input as preliminary excitation is increased, and the electron rose 1 is used as a deposit increasing type. This prevents the transition from glow discharge to arc discharge, so that all of the input energy can be used for glow discharge.

〔Effect of the invention〕

As described above, according to the present invention, since the second auxiliary electrode is provided between the first main electrode and the second main electrode which are arranged opposite to each other, the buffing of electrons by auxiliary discharge 1' @The number increases.

This allows stable glow discharge to be obtained without transitioning to arc discharge, extending the lifespan of the laser gas and laser @
This has the excellent effect of improving mounting efficiency.

[Brief explanation of drawings]

Figure 1 is a side cross-sectional view showing the electrode portion of a discharge-excited short pulse laser device according to an embodiment of the present invention, Figure 2 is a front cross-sectional view of the same, and Figure 8 is a cross-sectional view (8) showing a conventional device. be. In the figure, (8) is ilO main! pole, (9) is the second main electrode, αQ is the dielectric, CLI) is the first auxiliary! pole, (1
1 is a metal base, and (1) is a second auxiliary electrode. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] a first main electrode provided on a metal base; a second main electrode having a plurality of openings and disposed opposite to the first main electrode; and a back surface of the second main electrode. a dielectric body provided in close contact with the dielectric body; and a second dielectric body provided in close contact with the dielectric body;
a first auxiliary electrode facing the main electrode, and a second auxiliary electrode whose surface is covered with a dielectric, one of which is in contact with the second main electrode and the dielectric, and the other is fixed to the metal base. A discharge-excited short pulse laser device comprising: