JPS63227067A - Gas laser oscillator - Google Patents

Abstract

PURPOSE:To enable operation stably even by highly repetitive laser oscillation by forming a communicating section communicated with a cavity to a sidewall on the upstream side of a gas laser medium to the circulating gas laser medium in an electrode to which a pre-ionization electrode is disposed. CONSTITUTION:An anode 2 and a cathode 22, the inside of which has a cavity 6 while being opposed to the anode 2 and to the surface of which opposed to the anode 2 a plurality of pre-ionization holes 7 communicated with the cavity 6 are shaped, are mounted into a laser tube 1 into which a gas laser medium is sealed, and a pre-ionization electrode 8 forming glow discharge between the cathode 22 and the electrode 8 is arranged into the cavity 6. A communicating section 23 communicated with the cavity 6 on the inside of at least the upstream-side sidewall of the cathode 22 to the gas laser medium circulating in the electrode 8 is shaped to at least the upstream-side side surface of the cathode 22. Since not only a section between both the cathode and the anode forming main discharge but also the gas laser medium in the cavity 6 for the cathode 22 can be replaced, the generation of arc discharge between both the cathode and the anode can be prevented even by highly repeated laser oscillation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a gas laser oscillation device, and particularly to a pre-ionization type gas laser oscillation device.

(Prior art) In a gas laser oscillation device such as a TEACO2 laser excimer laser, in which a gas laser medium is sealed under a gas pressure higher than atmospheric pressure and laser light is emitted in a direction perpendicular to the discharge between the negative and negative poles, In order to stabilize the discharge between the two electrodes, preliminary ionization is performed prior to the discharge. Conventionally, this pre-ionization method includes an ultraviolet pre-ionization method using ultraviolet rays and a corona pre-ionization method using corona discharge. Among these, the corona pre-ionization method has the advantage that the gas laser medium is less degraded by one pre-ionization and can provide a laser excavation device with a long gas life.

FIG. 6 shows the configuration of a gas laser oscillation device using this conventional corona pre-ionization method. This gas laser oscillator is
Equipped with a laser tube (■) with an airtight structure in which a gas laser medium is sealed, an anode (■) and a cathode (■) opposite this anode (■) are installed inside the tube, each connected to a high-voltage power source (which generates high voltage and large current pulses). Connected to the wall and high pressure grate.

Roughly speaking, the anode ■ and cathode (3) are these two poles ■,
(3) Connected through a peaking capacitor (■) in order to form the waveform of the discharge generated between them.

Further, the cathode (2) has a cavity 0 formed inside thereof, and a plurality of pre-ionization holes (2) communicating with the cavity 0 are formed on the surface facing the anode (2). A corona wire (2) for preliminary ionization that generates a glow discharge between the cavity (0) and the cathode (2) is disposed within the cavity (0). This corona wire (8
) is connected to the anode (■) via a capacitor (○) that divides the voltage applied to this corona wire (○). In addition, inside the laser tube 0), there are negative and positive poles ■, (3
) and a heat exchanger (6) for cooling the gas laser medium are installed.

In this gas laser oscillator, the peaking capacitor ■ is charged by the voltage supplied from the high-voltage power supply (), and when the cathode ■ becomes high voltage with respect to the anode ■ and the corona wire (8), the voltage from the cathode ■ to the corona wire (8) Since the distance is shorter than the distance to the anode (2), a glow discharge occurs between the cathode (2) and the corona wire (8).

Electrons generated by this glow discharge pass through the pre-ionization hole ω and are emitted between the negative and negative poles (2) and 0, pre-ionizing the negative and positive poles (4) and 0. As this pre-ionization progresses, the peaking capacitor ■ becomes sufficiently charged and the voltage of the cathode ■ further increases.
A main discharge occurs between the anode and the anode ■, causing laser oscillation.

By the way, in this pre-ionization type gas laser oscillator, in order to oscillate the laser at a high repetition rate of several times per second, before the main discharge occurs, the ions and electrons generated in the previous main discharge must be It is necessary to expel it from between the yin and yang polarities■ and 0. That is, if ions or electrons remain between the negative and positive poles 1 and 0, the next discharge becomes an arc discharge, and no laser is emitted. In conventional gas laser oscillation devices, this problem was prevented by circulating the gas laser medium using a fan 0Φ.

However, even if the gas laser medium is circulated by the fan θ, the gas laser medium in the cavity 0 cannot be replaced sufficiently with the cathode ■, which only has pre-ionized holes ■ formed on the surface facing the anode ■. Therefore, if the repetition is repeated 10 to 50 times per second, the cathode ■ and the corona wire (
The discharge between
There is a problem that the laser cannot be oscillated.

(Problems to be Solved by the Invention) As described above, the conventional pre-ionization type gas laser oscillation device has a structure in which the cathode only has pre-ionization holes formed on the surface facing the anode. Even if the gas laser medium circulates in the direction perpendicular to the main discharge, the gas laser medium in the anode cavity cannot be replaced sufficiently. Therefore, when high-repetition laser oscillation is performed, there is a gap between the cathode in the cavity and the corona wire. There is a problem in that arc discharge occurs, pre-ionization becomes spatially non-uniform, the main discharge between the negative and positive electrodes shifts to arc discharge, and the laser no longer oscillates.

The present invention has been made to solve these problems, and an object of the present invention is to provide a pre-ionization type gas laser oscillation device that operates stably even when performing high repetition laser oscillation.

[Structure of the invention]

(Means for solving the problem) A laser tube in which a gas laser medium is sealed has an anode and a cavity on the inside facing the anode, and a plurality of holes are connected to the cavity on the surface facing the anode. A cathode having a pre-ionization hole formed therein is installed, and a pre-ionization electrode for generating a glow discharge between the cathode and the cathode is disposed in the cavity, and the gas laser medium sealed in the laser tube is connected to the cathode and the cathode. In a gas laser oscillator device configured to circulate in a direction perpendicular to a main discharge generated between the two electrodes, communication is provided to at least the upstream side of the cathode with respect to the circulating gas laser medium, and the communication leads to the inner cavity of the cathode. The division was formed.

(Function) As described above, by forming a communication section, not only the cathode and cathode electrodes that generate the main discharge, but also the gas laser medium inside the cathode cavity can be exchanged, so even if high-repetition laser oscillation is performed. , it is possible to prevent arc discharge between the cathode and the pre-ionization electrode in the cavity, and therefore to prevent the occurrence of arc discharge between the negative and anode electrodes.

(Example) Hereinafter, the present invention will be described based on an example with reference to the drawings.

FIG. 1 shows the configuration of a gas laser oscillation device according to an embodiment of the present invention. This gas laser oscillation device has the same structure as a conventional gas laser oscillation device, except for the cathode.
A pair of support plates (A) and @ are fixed to the inside of the laser tube ω in an airtight groove in which the gas laser medium is sealed, and an anode ■ and a cathode constituting the main discharge electrode are attached to these support plates (A) and ■. @ are installed facing each other. And the anode ■ is
The high voltage is connected to the ground side of the high voltage power supply that generates the atmospheric flow pulses, while the cathode is connected to the high voltage side. Furthermore, a peaking capacitor (2) is connected between the negative and negative poles @ and 0 to form a discharge waveform between them. The negative and negative poles @ and ■ are each formed into a semicylindrical shape and are arranged in parallel so that a required equal electric field is formed between them. In particular, the cathode @ has a cavity 0 formed inside it, and a plurality of pre-ionization holes (■) communicating with the cavity 0 on the surface facing the anode (■).
is formed. In the cavity 0, a corona wire (2) serving as a preliminary ionization electrode is disposed. This corona wire is connected to the anode through a capacitor that divides the voltage applied to it. The distance from this corona wire (c) to the cathode @ is shorter than the distance between the negative and anode poles ■ and (c).
Easier to generate electric discharge. Furthermore, inside the laser tube (■), a fan 0Φ of a gas laser medium circulation device is installed that circulates the gas laser medium sealed in the laser tube (■) in a direction perpendicular to the main discharge generated between the negative and anode poles (■) and 0.
and a heat exchanger Ql) for cooling the circulating gas laser medium.

However, the cathode ■
As shown in FIG. 2, a communicating portion communicating with the inner cavity 0, that is, a plurality of gas laser medium inlet holes (23) are formed on the upstream side surface of the chamber.

By the way, this gas laser oscillation device uses a peaking capacitor (9) due to the voltage supplied from a high voltage power supply (0).
is charged, and the cathode @ is connected to the anode ■ and the corona wire (8
), a glow discharge occurs between the cathode @ and the corona wire (c). Electrons generated by this glow discharge pass through the preliminary ionization hole (2) and are emitted between the negative and positive poles (4) and 0, pre-ionizing the negative and positive poles (4) and 0.

Thereafter, as this pre-ionization progresses and the peaking capacitor (2) is further charged and the voltage at the cathode (@) becomes even higher, a main discharge is generated between the negative and anode poles (2) and (0), causing laser oscillation.

In this case, in this gas laser oscillation device, the circulating gas laser medium flows into the cavity 0 not only between the cathode and positive poles ① and 0, but also from the gas laser medium inflow hole (23) formed on the side surface of the cathode @. The gas laser medium inside the cavity 0 flows out from the preliminary ionization hole (2), and the gas laser medium inside the cavity 0 is replaced, so that a new gas laser medium is always supplied near the corona wire (8). Therefore, in this gas laser oscillation device, even if high-repetition laser oscillation is performed, the discharge between the cathode and the corona wire does not shift from glow discharge to arc discharge, unlike in conventional gas laser oscillation devices, and is stable. It can be a gas laser initiation device that operates.

By the way, as a means of evaluating high repetition rate laser oscillation operation,
There is a clearance ratio. This is the value of how many times the width of the main discharge is required for the gas transfer tube to generate from one discharge to the next, and it varies depending on the measurement method and pre-ionization method, but in many cases , 2 of the main discharge width
~5 times.

According to this clearance ratio, for example, if the main discharge width is 10 m and the clearance ratio is 4.5, then 1
The gas flow rate required to perform 100 repetitions per second is 10sX 4. Sx ioo times/sec = 4.5 m/sec. However, in conventional gas laser oscillation devices, even if the flow velocity of the gas laser medium is 4.5 m/s, when the laser oscillation is repeated 20 to 50 times per second, arc discharge occurs between the cathode and the corona wire. However, a stable main discharge could not be obtained. However, the gas laser oscillation device of this embodiment operates stably even if the repetition is performed 100 times or more per second under the same conditions.

In addition, such a gas oscillation device causes less deterioration of the gas laser medium and further extends the gas life of the gas laser oscillation device, which originally has a long gas life. Furthermore, in order to prevent arc discharge between the cathode (221) and the corona wire (8), the corona wire (8) is usually made of copper wire or the like.
) has the advantage of reducing wear and tear.

Next, other embodiments will be described.

In the above embodiment, a plurality of circular gas laser medium inflow holes were formed on the side surface of the cathode, but as shown in FIG. It may be formed into a shape to serve as a communication portion.

In addition to the gas laser medium inflow hole (23), FIG. A guide plate (25) is provided to guide the gas laser medium through the tip of the corona wire (8) toward the preliminary ionization hole (2). Please note that this information board (2
5) is preferably formed of an insulating member such as fluororesin that is resistant to ultraviolet rays generated by discharge between the cathode @ and the corona wire 〇.

If the guide plate (25) is provided in the cavity 0 in this way to improve the flow of the gas laser medium near the corona wire ■,
A gas laser oscillation device that is more stable against high-repetition laser oscillation can be achieved.

In FIG. 5, a gas laser medium inflow hole (23) is formed on the upstream side of the circulating gas laser medium, and a gas laser medium outflow hole (26) is formed on the downstream side.

In this way, corresponding to the gas laser medium inlet hole (23), there is a gas laser medium outlet hole (23) on the downstream side of the gas laser medium.
26), the flow of the gas laser medium near the corona wire (c) improves as in the fourth illustrated example, and the gas laser oscillation device can be similarly stable against high-repetition laser oscillation.

In the above embodiment, the cathode was provided with a corona wire, but in this invention, the anode is formed in the same structure as the cathode,
A corona wire may be placed at this anode, or may be placed at both the negative and positive electrodes.

〔Effect of the invention〕

An anode and a cathode are installed opposite the anode in a laser tube in which a gas laser medium is sealed, and a cavity is formed inside the cathode that communicates with a plurality of pre-ionization holes formed on the surface facing the anode. and a pre-ionization electrode for generating a glow discharge between the cathode and the cathode is disposed in the cavity, and the gas laser medium sealed in the laser tube is perpendicular to the main discharge generated between the cathode and the cathode. In the gas laser oscillation device configured to circulate in the direction, a laser medium inflow hole communicating with the cavity of the cathode is formed on the upstream side surface of the gas laser medium of the cathode, so that there is no gap between the cathode and the cathode where the main discharge is generated. Instead, the gas laser medium is flowed into the cathode cavity and replaced with a new gas laser medium, so even if high-repetition laser oscillation is performed, the discharge between the cathode and the pre-ionization electrode will not become an arc discharge. Therefore, it is possible to provide a gas laser oscillation device that operates stably without causing arc discharge between the negative and negative electrodes.

Moreover, although the gas life is originally long, the gas life of the laser oscillator can be made even longer, and the consumption of the pre-ionization electrode can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of a gas laser oscillation device that is an embodiment of the present invention, Fig. 2 is a perspective view with a part of the cathode cut away, and Fig. 3 is a diagram showing the configuration of a gas laser oscillation device that is an embodiment of the present invention. FIGS. 4 and 5 are perspective views showing a partially cut away cathode of
The figures are cross-sectional views showing the structures of other cathodes, respectively.
The figure is a diagram showing the configuration of a conventional gas laser oscillation device. (G)... Laser tube (2)... Anode ■... Peaking condenser ■...
Cavity■... Pre-ionization hole (8)...Corona wire (9)...Capacitor (10)...Fan (22)...・・Cathode (23)・・Gas laser medium inflow hole (25)・
...Guidance plate (26) ... Gas laser medium outflow hole agent Patent attorney Inoue - Male 23 (hole to the shoulder) Fig. 1 Fig. 2' @ 3 Figure 4 Figure 5 Figure 6

Claims (3)

[Claims] (1) Consisting of a laser tube in which a gas laser medium is sealed and electrodes placed opposite each other within the laser tube, at least one of the electrodes has a cavity formed inside, and one of the electrodes A main discharge electrode has a pre-ionization hole communicating with the cavity formed on the opposite surface to the other electrode, a pre-ionization electrode arranged in the cavity, and a gas laser medium sealed in the laser tube. In a gas laser oscillation device including a gas laser medium circulation device that circulates a gas laser medium in a direction crossing the discharge between the discharge electrodes, the electrode on which the pre-ionization electrode is disposed has the above-mentioned gas laser medium on its upstream side with respect to the circulating gas laser medium. A gas laser oscillation device characterized in that a communication portion communicating with a cavity is formed. (2) The gas laser oscillation device according to claim 1, wherein the electrode in which the communication portion is formed has a guide plate that guides the gas laser medium flowing from the communication portion into the cavity. (3) The gas laser oscillation device according to claim 1, wherein the electrically conductive portion is provided on the downstream side of the gas laser medium.