JPH0318752B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a preliminary discharge type gas laser oscillation device.

[Technical background of the invention and its problems] TEA, which is one of the gas laser oscillation devices
(Transversely Excited Atmospheric
Pressure) CO ₂ lasers and excimer lasers use a pressure higher than atmospheric pressure as the operating pressure of the laser gas medium, so pre-ionization means for uniform discharge generation is required. One such means uses corona discharge, which supplies charged particles and ultraviolet light. TEACO ₂ with corona discharge preionization means
An example of a laser is shown in FIG. That is, 1 is an airtight container in which a laser gas medium consisting of a mixed gas of CO ₂ , N ₂ , He, etc. is sealed and maintained at a pressure of around 1 atmosphere. Inside the container 1, in an atmosphere of a laser gas medium, a semicylindrical cathode 2 constituting a main discharge electrode and an anode 3 having substantially the same shape as the cathode 2 are arranged facing each other, and are connected to a power source 4 that supplies a pulse voltage. ing. On the surface of the cathode 2 facing the anode 3, several V-grooves 5 of equal pitch are provided parallel to each other in the longitudinal direction. Each of these V-grooves 5 is provided with a preliminary corona discharge electrode 8 having a structure in which a core wire 7 is housed in a glass pipe 6. The core wires of the preliminary corona discharge electrode 8 are combined into one wire and connected to the anode 3. Further, a peaking capacitor 9 is provided between the cathode 2 and the anode 3 in a short-circuited manner with a short lead wire.

In the above configuration, the preliminary corona discharge electrode 8
is set to a number that narrows the width of the main discharge section. By the way, with this arrangement of preliminary corona discharge electrodes, preliminary ionization becomes stronger in the central part of the arrangement,
The current density in the main discharge region 10 is also high in the central portion. The intensity distribution of the laser beam obtained by such a main discharge action becomes a mountainous intensity distribution as shown in Fig. 5, which causes problems such as uneven processing in marking and other laser processing. Ta.

[Object of the Invention] An object of the present invention is to provide a gas laser oscillation device that can adjust the current density of the main discharge part and obtain a laser beam with a flat intensity distribution.

[Summary of the Invention] In order to achieve the above object, a plurality of preliminary corona discharge electrodes are arranged so as to cause a preliminary discharge to form a non-main discharge region in the center of the main discharge section.

[Embodiments of the Invention] The present invention will be described below with reference to drawings showing embodiments. Note that parts common to those in FIG. 5 are designated by the same reference numerals, and explanations thereof will be omitted.

That is, in the embodiment shown in FIG. 1 showing the main parts, one of the many preliminary corona discharge electrodes 8 is removed from the center. That is, two preliminary corona discharge electrode groups 8a and 8b are formed on the left and right sides when viewed from the side with the removed portion as the center. In this embodiment, connections to the power supply, peaking capacitor, etc. are omitted, but they have the same configuration as shown in FIG. 5.

With the above configuration, in the first half of the pulse voltage applied to the cathode 2 from the power source, corona discharge first occurs between each of the preliminary corona discharge electrodes 8 and the cathode 2 with a narrow electrode interval. As a result, the vicinity of the surface of the cathode 2 is sufficiently pre-ionized. At this time, since two preliminary corona discharge electrode groups 8a and 8b are formed, the preliminary ionization area is also divided into two, and as a result, the main discharge area 11 is divided into two as shown in the figure.
a, 11b are formed. Since preliminary ionization is not performed in the removed portion, a non-main discharge region 12 in which no main discharge occurs is formed in this portion. The current density of the two separated main discharge regions 11a and 11b is large in the center of each region. The laser light output from one of the optical resonators (not shown) excited by the above discharge action has an intensity distribution 13 in which the center part of the laser light is low and the peripheral part is high, as shown in FIG. Become. This intensity distribution 13 can be obtained by placing the preliminary corona discharge electrode groups 8a and 8b as close as possible and making the interval between the non-main discharge regions 12 narrower, so that a uniform intensity distribution 14 can be obtained as shown in FIG. It will be done.

In the above embodiment, the V-groove 5 on the surface of the cathode 2 in the removed portion of the preliminary corona discharge electrode was left as it is, but the function and effectiveness may be improved even if the V-groove is not formed in this portion in advance and the surface is made flat. remains almost unchanged. Furthermore, it goes without saying that the same result will occur even if only the copper wire 7 is removed regarding the preliminary corona discharge electrode.

[Effects of the invention] As detailed above, the main discharge region with strong current density is eliminated and laser light with a uniform intensity distribution is obtained, so processing with high energy utilization efficiency without processing unevenness is achieved. . This high energy utilization efficiency means that processing equivalent to processing using a laser beam with a non-uniform intensity distribution can be performed with 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 desired processing can be performed with a low laser output energy, the capacity of the capacitor, the voltage and capacity of the charging power supply can be saved, and the device can be made smaller. , gear switches, thyratrons, and other switch elements are also relaxed.

[Brief explanation of the drawing]

FIG. 1 is a side view of essential parts showing one embodiment of the present invention;
2 and 3 are energy distribution diagrams, FIG. 4 is a configuration diagram showing a conventional example, and FIG. 5 is an energy distribution diagram of laser light obtained in the conventional example. 1... Airtight container, 2... Cathode, 3... Anode, 8
... Preliminary corona discharge electrode, 8a, 8b ... Preliminary corona discharge electrode group, 11a, 11b ... Main discharge area,
12...Non-main discharge area.

Claims (1)

[Claims] 1. an airtight container enclosing a gas laser medium; a pair of main discharge electrodes each having a substantially flat plate shape with curved edges and disposed opposite to each other in the airtight container;
A gas laser oscillation device comprising a plurality of preliminary corona discharge electrodes disposed on at least one discharge surface of the main discharge electrode and facing the other discharge surface of the main discharge electrode at pitches forming a continuous main discharge region, the above-mentioned A gas laser oscillation device characterized in that the preliminary corona discharge electrode is omitted at the center of the arrangement to form a non-main discharge region at the center of the main discharge region.