JPS62163381A - Gas laser oscillator - Google Patents

Abstract

PURPOSE:To enable the attainment of laser beams having a leveled distribution of intensity by a construction wherein the core wires of a number of auxiliary discharge electrodes juxtaposed on the surface of a main discharge electrode are made shorter as they are positioned nearer to the center of the row of the electrodes. CONSTITUTION:A vessel 1 wherein a gas laser medium is charged or made to circulate, a pair or more of main discharge electrodes composed of a cathode 3 and an anode 2 provided opposite to each other in the gas laser medium in said vessel, optical resonators 8, 9 provided on the opposite sides of the cathode 3 so that the direction of the optical axes thereof is made to intersect the direction of discharge of the main discharge electrode, and a number of auxiliary discharge electrodes 11 each of which has a structure of a core wire 13 being held in a glass tube and which are provided in juxtaposition along he longitudinal direction on the surface side of the cathode 3 opposite to the anode 2 so as to induce main discharge, are provided. The auxiliary discharge electrodes 11 in a gas laser oscillator constructed in this way are made to have shorter core wires 13 as they are positioned nearer to the center of the row. The length of each of the aforesaid core wires 13 is set, for instance, so that an axial symmetry is formed around the core wire 13-1 of an auxiliary discharge electrode 11-1 positioned in the center of the row.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a preliminary discharge type gas laser oscillation device.

[Technical background of the invention and its problems]

Figure 5 shows TEA (Transversely Exc
ited Atmosphere pressure
) FIG. 2 is a schematic diagram showing an electrode section of a gas laser oscillation device from which a v-sum or excimer laser is emitted. That is, a plate-shaped anode (2) and a cathode (3) are provided facing each other in a gas laser medium in a container (1) in which the gas laser medium is enclosed or circulated. This anode (
2) and the cathode (3) constitute a main discharge electrode. There are many V grooves (4) on the surface of the cathode (3) facing the anode (2).
is carved along the longitudinal direction (perpendicular to the plane of the paper) of the cathode (3). Glass tubes (5) are installed in these V grooves (4).
A preliminary discharge electrode (forced) has a structure in which a core wire (6) such as a copper wire is housed inside. By the way, in the past, the preliminary electrode (sword is a glass tube (5) as shown in Fig. 5), Core wire (
6) Both are provided so as to span the entire length of the cathode (3) in the longitudinal direction and cover most of the surface of the cathode (3).

In the above configuration, when a light beam of 11 tg is supplied to the main discharge electrode 3 and the preliminary discharge electrode, an ozonizer-type corona discharge is generated between the core wire (6) and the cathode (3).

This corona radiation supplies a large amount of charged particles to the surface of the cathode (2) and irradiates it with ultraviolet light.

Pre-ionization takes place between the cathode (3) and the anode (3).

The supplied ions and electrons are accelerated by this pre-ionization effect, and the electric field increases like an avalanche, leading to a main discharge. The main discharge is normally maintained for 1 to 2 μs, and the gas laser medium is excited by the main discharge lζ, and pulsed laser light (L) is output from one of the optical resonators (8) and (9).

In the above, preliminary release '\! Since the electrode is provided so as to cover most of the surface of the cathode (3), during pre-ionization, the pre-ionization is stronger in the central part of one row, and the current density in the main discharge area aC is also lower in the central part. It gets expensive. Also,
The density of the gas laser medium excited by the discharge depends on the current density 1, and the higher the current density, the higher the density of the gas laser medium excited, and the intensity distribution (S , ) form a mountain as shown in FIG. For example, when a laser beam with such an intensity distribution is irradiated with the entire beam onto a mask with a predetermined pattern, and marking processing is performed using the laser beam that has passed through the pattern, both ends of the pattern become unclear.
There was a problem that good machining could not be performed.

[Purpose of the invention]

An object of the present invention is to provide a gas laser oscillation device that can obtain laser light with a flat intensity distribution.

[Summary of the invention]

In a gas laser oscillation device equipped with a large number of preliminary discharge electrodes that are made up of a glass tube and a core wire housed in the glass tube and are arranged in parallel on the surface of a main discharge electrode, the preliminary discharge electrode is placed one in the center of the row. The above object is achieved by making the length of the core wire shorter as it is positioned.

[Embodiments of the invention]

The present invention will be explained below based on FIG. 1 showing an embodiment.

Figure 1 is compared with Figure 5, which is a conventional example, and shows preliminary discharge electrodes (Lυ is the fourth
This differs from the conventional example shown in the figure in that the lengths of the core wires are made unequal. That is, in the case where seven preliminary discharge electrodes are arranged in parallel as shown in Figure 1.

The glass tube α, which forms one part of the structure, is the same for all.

The preliminary discharge electrodes (11-1) on both sides are centered around the core wire (13-1) of the preliminary discharge electrode (11-1) located in the center.
2) to (11-7) core wires (13-2) to (13-
7) is sequentially longer than the core wire (13-1) in the following relationship. In other words, the above core! (13-1) to (1
The relationship between each of the thorns Jl) to (J,) in 3-7) is '1 <'2''Ll<L4mi1.<16-=1
．． The relationship is as follows, and they are axially symmetrical about the core line (13-1).

Due to the above (I!) formation, the pre-ionization effect occurs only in the area where the 8 starches are provided, so the area where the main discharge is formed is the cathode (3) and the anode (2) as shown in Figure 3. ) when viewed as a plane, the main discharge part (I!19) is formed with a shape corresponding to each length of the core wire with a lower central part on one side (I! 19). By shortening the discharge length in the central part of the electrode and lengthening the discharge length in the pre-discharge electrode parts at both ends where the current density is low, the difference in gain caused by the difference in current density is corrected by the discharge length, and the number of cars JfIL electrode can be reduced. It was possible to make the amplification factor distribution uniform in the longitudinal direction.In the above example, the glass tube was made common regardless of the length of the core wire, but even if the glass tube was shortened according to the length of the core wire, good.

〔Effect of the invention〕

By making the distribution of the amplification factor uniform as described above, it is possible to obtain a laser beam with an intensity distribution (St) that has a flat energy as shown in Figure 3, resulting in efficient use of energy without uneven processing. Processing is now possible. The high efficiency of energy use means that the required sword loe can be produced with relatively low energy. The laser output energy is proportional to the amount of charge stored in the main capacitor of the power supply circuit, but if the required processing can be performed with a low laser output energy, the capacity of the capacitor, the voltage and capacity of the charging power source can be saved, and the size can be reduced. As well as being able to.

Requirements for switching elements such as gap switches and thyratrons will also be relaxed.

[Brief explanation of drawings]

Fig. 1 is a plan view showing an embodiment of the present invention, Fig. 2 is a diagram showing the main discharge part in the above embodiment, Fig. 3 is an intensity distribution diagram of the laser beam, and Fig. 4 is a cross-sectional view of the gas laser oscillation device. side view,
FIG. 5 is a plan view showing a conventional example. (1)... Container, (2)... Anode. (3)...Cathode, (8), (9)...
・Optical resonator. αυ...Preliminary discharge ¥1 electrode, α2...Glass tube. (13-1) to (13-7) Core wires. Agent Patent Attorney Noriyuki Chika Yudo Kikuo Takehana Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) A gas laser medium, a container in which the gas laser medium is sealed or circulated, at least a pair of main discharge electrodes consisting of a cathode and an anode provided oppositely in the gas laser medium in the container, and an optical axis direction of the main discharge electrode. An optical resonator is provided on both sides of the cathode so as to cross the discharge direction of the discharge electrode, and a core wire is housed in a glass tube. 1. A gas laser oscillation device comprising a large number of preliminary discharge electrodes provided to cause a main discharge, wherein the preliminary discharge electrodes have core wires that become shorter as they are located at the center of the row. (2) The gas laser oscillation device according to claim 1, wherein the length of the core wire is axially symmetrical about the core wire of the preliminary discharge electrode located at the center of the row.