JPH05259552A - Gas lasing apparatus - Google Patents

Abstract

PURPOSE:To eliminate water content in laser gas which causes laser oscillation imperfection. CONSTITUTION:The title apparatus consists of the following; a pair of planar main electrodes 11, 12, a pair of auxiliary electrodes a plurality of which are arranged along the side ends of the main electrodes 11, 12, a chamber outer wall 41 constituting a chamber in which the main electrodes and the auxiliary electrodes are accommodated, a gas feeding pipe through which laser gas is supplied from the outside, a highly reflecting mirror and a high emission mirror for casting a laser beam, a fan 30 for circulating the laser gas in the chamber, and water content adsorption mechanism 71, 72 for eliminating water content existing in the gas feeding pipe or the chamber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas laser oscillator.

[0002]

2. Description of the Related Art Recently, it has been recommended to use a pulsed gas laser oscillator for marking various products. This is because when marking characters, trademarks, model numbers, manufacturing dates, etc. on semiconductor / electronic parts, mechanical parts, etc. at high speed and clearly, the timing of marking and the movement of articles is easy. Currently, there is a TEA-CO ₂ laser device as a gas laser oscillator of this type. FIG. 3 is a schematic explanatory view of such a conventional gas laser oscillator. 4 shows a cross-sectional view taken along the line BB shown in FIG. First, the configuration of the gas laser oscillator will be described. 11 is an anode forming a main electrode, 12 is a cathode forming a main electrode, 21 is an anode of a pair of preionization pins forming an auxiliary electrode, 22 is a pair of preionization pins forming an auxiliary electrode Cathode, 30
Is a fan that sends laser gas to the discharge space 40, 31 is a rectifying plate that regulates the flow of gas, 50 is a high-reflection mirror, 60 is an emission mirror, 41 is an outer wall of the chamber, and RG is a laser gas pressure control valve. Then, the laser gas, for example, carbon dioxide gas is supplied from the gas cylinder GB into the chamber through the gas supply pipe 90. Next, the operation will be described. First, ultraviolet rays are generated by causing a spark discharge between the pair of preionization pins 21 and 22. This ultraviolet ray pre-ionizes the laser gas in the discharge space 40. In this state, when a high voltage is applied between the anode 11 and the cathode 12 to cause discharge next between the main electrodes, glow discharge occurs between the main electrodes. The laser gas pre-ionized in advance is excited by this glow discharge to emit light, and the laser device oscillates by the high-reflection mirror 50 and the emission mirror 60 that form a resonator. On the other hand, by removing the laser gas heated by the discharge from the discharge space,
The fan 30 has an anode 11 to replace with fresh laser gas.
Are provided along the inner side of the outer wall of the chamber in the longitudinal direction. Further, by providing the rectifying plate 31, the flow velocity distribution of the laser gas is kept uniform, and the stable laser oscillation is achieved by the uniform glow discharge. In other words, the laser gas is discharged in the chamber as indicated by the arrow.
It circulates to pass 40.

However, even if the fan and the rectifying plate are provided as described above, the laser oscillation may be defective. Therefore, when it is used as a marking device, an article without a mark is generated, which is a cause of impeding automation of the marking process of the article. The failure of laser oscillation means that uniform glow discharge does not occur between the main electrodes and arc discharge occurs intensively at one place. Since the occurrence of arc discharge means partial discharge between the main electrodes, laser oscillation is very unstable and its output is low.
The cause of this is considered to be the water content contained in the laser gas. Therefore, the amount of water contained in the laser gas,
I investigated the relationship between the number of arc discharges. The result is shown in FIG. In the figure, the horizontal axis shows the amount of water in the discharge space relatively. Similarly, the vertical axis represents the number of times of arc discharge. From this figure, it can be seen that when the amount of water exceeds a certain value P, arc discharge rapidly occurs. Thus, the water content contained in the laser gas hinders uniform glow discharge between the main electrodes and causes arc discharge. The power consumption of the TEA-CO ₂ laser device used here is 6
It is 0 W and the energy of one pulse is 6 joules. A CdS detector is used as an arc monitor to detect the number of times of arc generation, and strong light such as ultraviolet rays generated by arc discharge is detected.

[0004]

As described above, when water is present in the discharge space between the main electrodes, arc discharge easily occurs. Even if the arc discharge does not occur and the glow discharge occurs, if the discharge space has water, the output of the laser significantly decreases. The possible causes of the presence of water in the laser gas are that the water in the air when the device was assembled remains on the surfaces of the components in the chamber, and also when the gas cylinder for supplying the laser gas is replaced. For example, water is mixed in. Furthermore, it is conceivable that water may come out from the resin or the like on the outer wall of the chamber forming the device.

The present invention has been made in order to solve such a conventional problem, and an object thereof is to provide a gas laser oscillating device free from oscillation failure due to water in the laser gas.

[0006]

In order to achieve the above object,
The gas laser oscillating device of the present invention comprises a pair of plate-shaped main electrodes arranged to face each other, a pair of auxiliary electrodes for preionization arranged side by side along the side edges of the main electrodes, An outer wall of a chamber that constitutes a chamber in which an electrode and an auxiliary electrode are housed, a gas supply pipe to which a laser gas is externally supplied, and a laser beam are emitted to a discharge space in which the main electrode discharges. In a gas laser oscillator comprising a high reflection mirror and an emission mirror arranged so as to sandwich the discharge space, and a fan for circulating a laser gas in the discharge space, a moisture adsorption mechanism is provided in the chamber or in the middle of the gas supply pipe. It is characterized by being provided.

[0007]

With this structure, the water in the laser gas can be removed by the water adsorption mechanism.

[0008]

FIG. 1 is a schematic explanatory view of a gas laser oscillator according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA shown in FIG. 71, 72 in the figure
Indicates a moisture adsorption case. The water adsorption cases 71, 72 are plastic boxes, and have a vent hole on the side surface through which gas passes. The moisture adsorbing cases 71, 72 contain a moisture adsorbing agent such as molecular sieve (trade name). Reference numerals 81 and 82 denote cooling mechanisms in which a cooling liquid such as liquid nitrogen flows along the outer wall of the chamber. This cooling mechanism should be installed as close as possible to the water adsorption mechanism. In addition, the same reference numerals as those in FIGS. 3 and 4 denote the same parts. For the operation of laser oscillation, see FIG.
Since it is the same as the case of the conventional gas laser oscillator shown in FIG. 4, its explanation is omitted. Gas cylinder GB to gas supply pipe 90
A laser gas is supplied into the chamber via. The gas in the chamber is circulated by the fan 30 as indicated by the arrow in the figure. The laser gas circulating in the chamber is
Be sure to pass through the moisture adsorption cases 71, 72. That is, a moisture adsorption mechanism is provided on the gas circulation path. Therefore, the water contained in the laser gas is adsorbed by the water adsorbent during the circulation of the laser gas. Further, when a cooling liquid such as liquid nitrogen is flown through the cooling mechanisms 81 and 82, the water in the laser gas is trapped around the cooling mechanisms 81 and 82 during circulation, so that the water can be more effectively adsorbed. You can

The water adsorption case containing the adsorbent does not necessarily have to exist in the chamber.
It can also be installed in the middle of the gas supply pipe that connects GB to the chamber.

[0010]

As described above, in the gas laser oscillating device for circulating the laser gas, by providing the water adsorption mechanism in the circulation path, the water in the laser gas can be removed while using the device. It is possible to provide a gas laser oscillator in which arc discharge does not occur and laser output does not decrease. Therefore, an excellent marking device can be provided.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a laser oscillator according to the present invention.

FIG. 2 shows a cross-sectional view taken along the line AA shown in FIG.

FIG. 3 is a schematic explanatory view of a conventional laser oscillation device.

FIG. 4 shows a cross-sectional view taken along the line BB shown in FIG.

FIG. 5 is a diagram showing the relative amount of water in the discharge space and the number of times arc discharge occurs.

[Explanation of symbols]

 11 Anode that constitutes a main electrode 12 Cathode that constitutes a main electrode 21 Anode that constitutes an auxiliary electrode 22 Cathode that constitutes an auxiliary electrode 30 Fan 31 Rectifying plate 40 Discharge space 41 Chamber outer wall 50 High reflection mirror 60 Emission mirror 71 Moisture adsorption case 72 Water Adsorption Case 81 Cooling Mechanism 82 Cooling Mechanism 90 Gas Supply Pipe

Claims (1)

[Claims] 1. A pair of plate-shaped main electrodes arranged to face each other, a pair of auxiliary electrodes for preionization arranged side by side along a side edge of the main electrode, and a main electrode and an auxiliary electrode. The outer wall of the chamber that constitutes the chamber to be housed, the discharge space where the main electrode discharges inside the chamber, the gas supply pipe to which the laser gas is supplied from the outside, and the discharge space so that the laser beam is emitted are sandwiched. In a gas laser oscillating device comprising a high-reflection mirror and an emission mirror arranged in the above, and a fan for circulating a laser gas in the discharge space, a water adsorption mechanism is provided in the chamber or in the middle of the gas supply pipe. Gas laser oscillator.