JPH02268476A - Pulse gas laser oscillator - Google Patents

Abstract

PURPOSE:To enable uniform pre-ionization even if a main stroke space is relatively large by pre-ionizing from three directions against the main stroke space. CONSTITUTION:When a charge capacitor 12 is charged by a high voltage dc power source 11 and a thyratron 14 is 'ON', a voltage of the capacitor 12 is applied to both ends of a coil 13 and discharge develops between pin electrodes 6, 7. Ultraviolet rays produce through the pre-discharge, a discharge space section is pre-ionized, the pre-ionization produces at both sides of a cathode 3, and pre-ionization acts as far as a central part represented by a surface along a return stroke direction through a resonant axis. A peaking capacitor 15 is charged to a high voltage through the pre-discharge, a pulse voltage is applied between the cathode 3 and the anode 5, corona discharge develops through a dielectric 8 and a through-hole 4, and pre-ionization acts toward all over the cathode 3. Return stroke is caused between the cathode 3 and the anode 5, thereby exciting gas laser medium and carrying out laser oscillation.

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention relates to a pulsed gas laser oscillation device.

(Prior art) In so-called lateral excitation type pulsed gas laser oscillators such as excimer lasers and TEACO2 lasers, in order to stabilize the main discharge, a preliminary discharge electrode is provided near the main discharge electrode, and the main discharge space is A method of pre-ionizing is adopted. On the other hand, as the size of the device increases, the cross-sectional area of the main discharge space increases, and in order to make the main discharge more stable, (a) Japanese Patent Laid-Open No. 137380/1983 discloses a structure in which the main discharge electrode is configured. A technique is disclosed in which pre-ionization electrodes are provided on both the cathode and the anode. In this technique (a), a preliminary ionization electrode whose core wire is surrounded by a dielectric material is provided over almost the entire discharge surface of the main discharge electrode. Separately from this, (b) Japanese Patent Laid-Open No. 57-88789 discloses a structure in which auxiliary electrodes are provided in the vicinity of both mushroom-shaped main discharge electrodes. In this technique (b), the main discharge electrode is a mesh electrode with holes.

(Problem to be Solved by the Invention) When the main discharge space is enlarged by increasing the distance between the main discharge electrodes and the width and length of the electrodes themselves, a corona preparatory M electrode is added to the back surface or the discharge surface of the conventional main discharge electrode. If provided, pre-ionization will not sufficiently penetrate through the central axis of the main discharge space to the vicinity of the plane parallel to the discharge surface. Furthermore, in a system in which bottle-shaped preliminary ionization electrodes that generate ultraviolet rays are provided on both sides of the main discharge electrode, the width of the main discharge electrode is large, so that the ultraviolet rays do not penetrate sufficiently to the vicinity of the plane perpendicular to the plane parallel to the discharge plane. That is,
It has been difficult to increase the width of the main discharge electrodes and the distance between the main discharge electrodes. Therefore, a method of irradiating X-rays has been considered, but this method not only requires large-scale equipment, but also has the disadvantage of increasing material restrictions, such as making the main discharge electrode an X-ray transparent material. Ta. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a gas laser oscillation device that can uniformly pre-ionize a main discharge space having a large cross-sectional area.

[Structure of the invention] (Means and effects for solving the problem) An airtight container containing a gas laser medium, at least a pair of main discharge electrodes provided in the airtight container, and a preliminary discharge space for the main discharge electrode. In a pulsed gas laser oscillation device comprising a pre-ionization means for ionizing and an optical resonator provided facing each other with the discharge space in between, the pre-ionization means is provided on one both sides of the main discharge electrode. The first
and a second pre-ionization means that generates corona discharge over almost the entire surface of the main discharge on the other discharge surface of the main discharge electrode. Pre-ionization effects begin to occur from the side.

(Example) Hereinafter, the present invention will be described based on drawings showing examples. In Figure 1, an airtight container (1
), and a main discharge electrode and a preliminary ionization function are provided in this airtight container (1).

The main discharge electrode is held by a conductive holding plate (2), has a cathode (3) with a chang-shaped profile, and is provided opposite to this cathode, and has a plurality of through holes (4) on almost the entire surface. It consists of a flat plate-shaped anode (5) with holes. On the other hand, the pre-ionization means is a first pre-ionization means that is formed into pairs with a spark gap between a plurality of first bottle electrodes (8) which are attached at a predetermined pitch so as to hang down on both sides of the holding plate (2). In addition to the plurality of second pin electrodes (7) facing each other, a back electrode is provided as a second pre-ionization means on the back side of the anode (5) and has a dielectric (8) sandwiched between the anode (5) and the second pre-ionization means. (
9). The second pin electrode (7) is provided with electrical insulators (l) on both sides of the holding plate (2).
It is inserted and held with O) interposed therebetween. Although the optical resonators are not shown, they are placed facing each other in a direction perpendicular to the plane of the paper with a discharge space in between. A circuit for supplying high voltage pulses to the main discharge electrode and the preliminary ionization electrode is configured as follows. That is, it has a high-voltage DC power supply (11), and a charging circuit is formed by a charging/discharging capacitor (12) and a coil (13). In this charging/discharging circuit, a thyratron (1
4) is connected, and one end of this thyratron (14) is grounded.

The charging circuit is connected to the anode (5) and the second pin electrode (8) to form a discharge circuit. In this discharge circuit, a peaking capacitor (15) is connected between each first pin electrode (6) and the anode (5). In addition, a coupling capacitor (
IG) is connected.

Next, the operation of the above configuration will be explained. When the high-voltage DC power supply (11) is turned on and the charging/discharging capacitor (12) is charged and rising to a predetermined voltage, when the thyratron (14) is turned on, the voltage accumulated in the charging/discharging capacitor (12) is transferred to the coil (13). ), and a discharge occurs between the first and second pin electrodes (6) and (7). This preliminary discharge generates ultraviolet rays and pre-ionizes the discharge space. Since this pre-ionization occurs on both sides of the cathode (3), the pre-ionization effect is applied to the central portion represented by the plane passing through the resonance axis and along the main discharge direction. The peaking capacitor (15) is charged to a high voltage by the above preliminary discharge. As the peaking capacitor (15) is charged to a high voltage, a pulse voltage is applied between the cathode (3) and the anode (5). This is applied via a dielectric (8) through a coupling capacitor (1B) between an anode (5) which also serves as a corona pre-i electrode and a back electrode (9). Since the anode (5) has a plurality of through holes (4) drilled all over its surface, the dielectric (8)
), a strong electric field is generated in the through hole (4) and a corona discharge occurs. This corona discharge ionizes the vicinity of the discharge surface of the anode (5), and pre-ionization occurs toward the entire surface of the cathode (3). Here, a main discharge is caused between the cathode (3) and the anode (5) by a strong electric field due to the voltage of the peaking capacitor (15) that has risen between the main discharge electrodes, which excites the gas laser medium and causes laser oscillation.

In the above embodiment, a preliminary electrode that generates ultraviolet rays and a preliminary electrode that generates corona are provided on the cathode side, but there is no problem in a configuration in which the cathode and anode are reversed. Furthermore, in place of the pin electrode, a similar effect can be obtained by using a preliminary electrode in which a corona wire is surrounded by a dielectric vibrator. Furthermore, instead of the combination of a dielectric and a back electrode, a preliminary ionization means that generates ultraviolet light may be used.

[Effects of the Invention] One of the main discharge electrodes applies pre-ionization to the main discharge space from both sides, and the other main discharge electrode applies pre-ionization to almost the entire surface of the opposing main discharge electrode. Since the main discharge space is pre-ionized from three sides so as to have a positive effect, even if the main discharge space is relatively large, pre-ionization can be performed uniformly. As shown in (a) in the figure, the center is strong,
Although the oscillation beam had a weak energy distribution at the periphery, the preliminary ionization from the three directions described above made it possible to create an oscillation beam with a flat energy distribution as shown in FIG. 2(b).

When such a beam is used as a light source for marking or exposure, for example, it achieves bright marking and exposure without causing uneven irradiation.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing the energy distribution of a laser beam. (1) ... Airtight container (3) - Cathode (main discharge electrode) (4) ... Through hole/anode (main discharge electrode) - First pin electrode (first pre-ionization means) - Second Pin electrode (first pre-ionization means)

Claims (1)

[Claims] an airtight container enclosing a gas laser medium, at least one pair of main discharge electrodes provided in the airtight container, a pre-ionization means for pre-ionizing a discharge space of the main discharge electrode, and facing each other with the discharge space in between. In the pulsed gas laser oscillation device, the pre-ionization means includes a first optical resonator provided on both sides of one of the main discharge electrodes.
A pulsed gas laser oscillation device comprising: a pre-ionization means; and a second pre-ionization means for generating a corona discharge over substantially the entire surface of the main discharge on the other discharge surface of the main discharge electrode.