JPS633475B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas laser device having two or more discharge paths.

FIG. 1 shows an outline of a circuit used in a conventional gas laser device. In FIG. 1, a laser tube 1 has anodes 3, 4 and a cathode 5, and has two discharge paths. Furthermore, anodes 3 and 4 are connected to one output terminal of each of the high voltage power supplies 10 and 11 through trigger circuits 8 and 9 and ballast resistors 6 and 7.

When the high-voltage power supplies 10 and 11 generate a discharge sustaining voltage for each discharge path of the laser tube 1, and the trigger circuits 8 and 9 generate trigger voltages, each discharge path starts discharging. When the discharge starts, the trigger voltage disappears by itself, and the negative feedback action of the ballast resistors 6 and 7 stabilizes the discharge current.

However, since the laser tube 1 has a third discharge path between the anodes 3 and 4 of the laser tube 1 in addition to the regular two discharge paths, even if this third discharge path discharges,
The trigger voltage disappears by itself, and the state becomes as if two normal discharge paths were discharged. In this case, either of the anodes 3 or 4 becomes a cathode, causing the electrode to sputter and damaging the laser tube 1. Of course, the laser oscillation output 2 also decreases and stops.

SUMMARY OF THE INVENTION An object of the present invention is to provide a gas laser device that can improve the above-mentioned drawbacks, start and maintain normal discharge in two discharge paths, and obtain stable laser oscillation output.

The present invention provides a gas laser device having a laser tube having two or more discharge paths, a power source that supplies high voltage to each discharge path, and a trigger circuit, in which a photodetection circuit is provided for each discharge path, and the discharge light of these discharge paths is detected. The present invention is characterized in that a discharge detection circuit is provided to control the trigger circuit after detection.

The present invention will be described below with reference to the embodiment illustrated in FIG. In FIG. 2, the laser tube 1 has an anode 3,
4 and a cathode 5, and has two discharge paths. In addition, the anode 3,
4 is connected. Furthermore, anodes 3 and 4 are connected to one output end of the trigger circuit 17 through backflow prevention diodes 12 and 13. Photodetectors 25 and 26 are provided in each of the two discharge paths, and the comparison amplifiers 23 and 2 are connected to the photodetectors 25 and 26.
4. Connect to the input of the discharge detection circuit 16 through resistors 20 and 21 and diodes 14 and 15, respectively.
Furthermore, this input terminal is grounded via a resistor 19 and a positive bias power supply 18. Discharge detection circuit 16
The output of is connected to the trigger circuit 17.

In such a circuit configuration, the high voltage power supply 10,
11 generates a voltage higher than the discharge sustaining voltage of each discharge path of the laser tube 1, and the trigger circuit 17 generates a trigger voltage. Therefore, between the anode 4 and cathode 5 of the laser tube 1, the anode 3
Assuming that the discharge starts earlier than between and cathode 5,
Since the output voltage of the photodetector 26 increases and reaches the voltage of the reference power supply 22, the output voltage of the comparison amplifier 24 becomes positive, and the diode 15 is turned off. The bias voltage at the input terminal of the discharge detection circuit 16 is applied to the resistors 19 and 2.
Since the values of 0 and 21 are chosen equally, if the voltage of the reference power supply 18 is Ec, it will vary from +1/3Ec to +1/2Ec.
Therefore, the trigger circuit 17 cannot be stopped yet, and the trigger circuit 17 continues to generate the trigger voltage. Eventually, the discharge between the anode 3 and cathode 5, which had been delayed in discharge, also starts. As a result, the output voltage of the photodetector 25 rises and reaches the voltage of the reference power supply 22, so the output voltage of the comparison amplifier 23 becomes positive and the diode 14 turns off, so the bias of the discharge detection circuit 16 becomes +Ec.
Therefore, the operation of the trigger circuit 17 is stopped, and the discharge paths between the anode 3 and the cathode 5 and between the anode 4 and the cathode 5 are normally discharged and stabilized. Further, since the trigger circuit does not stop during the discharge between the third discharge path anodes 3 and 4, the discharge between the anodes 3 and 4 is not maintained. As mentioned above,
According to the invention, deterioration of the electrodes of the anodes 3, 4;
If the laser tube 1 is damaged, the laser oscillation output will not decrease or stop.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional gas laser device.
FIG. 2 is a circuit diagram of an embodiment of the gas laser device of the present invention. 1... Laser tube, 2... Laser oscillation output, 3,
4... Anode, 5... Cathode, 6, 7... Ballast resistor, 8, 9, 17... Trigger circuit, 1
0, 11...High voltage power supply, 12, 13, 14, 15
...Diode, 16...Discharge detection circuit, 18,
22... Reference power supply, 19, 20, 21... Resistor,
23, 24...comparison amplifier, 25, 26...photodetector.

Claims (1)

[Claims] 1. In a gas laser device having a laser tube having two or more discharge paths, a power source that supplies high voltage to each of the plurality of discharge paths, and a trigger circuit for the discharge paths, a discharge light detection circuit for each of the discharge paths, and each of these. A gas laser device comprising: a discharge detection circuit that controls the trigger circuit after detecting discharge light in a discharge path.