JPH01114089A - Gas laser oscillator - Google Patents

Abstract

PURPOSE:To judge whether a discharge between a cathode and an anode is a glow discharge or an arc discharge by a method wherein the level change of a voltage applied between the electrodes and/or the change of a current applied between the electrodes are/is detected. CONSTITUTION:A first discharge judging means 20 judges whether a main discharge induced between a cathode 3 and an anode 4 is a glow discharge or an arc discharge. The divided voltage Vs of a voltage divider 21 is applied to the (+) input terminal of a comparator 22. On the other hand, a source voltage Vo is divided to produce a judgement reference voltage Vk which is applied to the (-) terminal of the comparator 22 to be compared with the voltage Vs for judgement. A second discharge judging means 30 detects the change of a current applied between the cathode 3 and the anode 4 and the discharge mode is judged by a comparator 33. In the case of the glow discharge, the voltage level of the comparator 22 varies significantly and attenuates. In the case of the arc discharge, the voltage level swings toward negative and turns quickly to zero. In the comparator 33, approximately contrary phenomena are shown so that the discharge mode can be judged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an improvement of a gas laser oscillation device having a function of detecting a discharge state.

(Prior Art) Gas laser oscillation devices include TEACO2 lasers and excimer lasers. FIG. 7 is a block diagram of a laser oscillation device, in which a gas laser medium 2 is sealed inside a laser tube 1, which is an airtight container. Inside the laser tube 1, a cathode 3 and an anode 4 are disposed facing each other, and each bin electrode 5.6 is disposed in parallel with the cathode 3 and anode 4. Note that the cathode 3 and the anode 4 have a semicylindrical shape, and a plurality of bin electrodes 5.6 are arranged along the longitudinal direction of the cathode 3 and the anode 4 at predetermined intervals. These bin electrodes 5.6 are commonly connected to the cathode 3 via peaking capacitors 7.8 for waveform shaping. Therefore, between the cathode 3 and anode 4 ^
When the voltage source 9 is connected and the switch 10 is closed, the cathode 3
A high voltage is applied between the electrode 4 and the anode 4 and to each peaking capacitor 7.8. Then, a discharge occurs in each bottle electrode 5.6, and the area between the cathode 3 and the anode 4 is pre-ionized by this discharge light. When the voltage level applied between the cathode 3 and the anode 4 reaches a predetermined level in this state, a main discharge occurs between the cathode 3 and the anode 4. Thus, this main discharge light resonates in an optical resonator (not shown) and is oscillated as gas laser light.

By the way, the main discharge generated between the cathode 3 and the anode 4 is a glow discharge with a spatially uniform electric field as shown in FIG. However, the main discharge may not become a glow discharge but instead become an arc discharge in which the electric field is locally concentrated. When such arc discharge occurs, the electrical energy is concentrated in a very small area, resulting in a decrease in the output of the oscillated gas laser light. Therefore, if such a gas laser oscillation device is applied to a marking device, the marking action will be incomplete, and even if it is applied to a laser-induced chemical reaction, the reaction will not proceed properly. Therefore, it is necessary to detect whether the discharge state is arc discharge. In particular, when gas laser light is oscillated several hundred times per second, as in the case of application to laser-induced chemical reactions, it is necessary to detect the discharge state each time the oscillation occurs.

Therefore, to detect arc discharge, a photodiode 11 is arranged between the cathode 3 and anode 4 so that the detection area is perpendicular to the direction of discharge, as shown in FIG. 9(a). Arc discharge is detected based on the intensity of the emitted light.

However, although arc discharge only needs to occur within the detection area of the photodiode 11 as shown in FIG.
), if arc discharge occurs outside the detection area of the photodiode 11, it cannot be detected at all. Further, even if arc discharge can be detected, depending on the gas laser medium, the difference in light intensity between arc discharge and glow discharge may not be significantly different, so arc discharge may not be detected reliably.

(Problems to be Solved by the Invention) As described above, arc discharge cannot be detected reliably.

Therefore, an object of the present invention is to provide a highly reliable gas laser oscillation device that can reliably detect arc discharge.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a gas laser medium that is provided in the vicinity of a cathode and an anode that are arranged to face each other inside an airtight container in which a gas laser medium is sealed and that generate a main discharge. In a gas laser oscillation device equipped with pre-ionization means for pre-ionizing, the change in the voltage level applied between the cathode and the anode and the change in the current value flowing between the cathode and the anode are detected, or both are detected. This gas laser oscillator is provided with a discharge determination means for determining whether the discharge generated between the two is a glow discharge or an arc discharge.

(Function) By providing such a means, one or both of the voltage level change applied between the cathode and the anode and the current value change flowing between the cathode and the anode can be detected, and the change in the voltage level applied between the cathode and the anode can be detected. It is determined whether the discharge that occurs between the two is a glow discharge or an arc discharge.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. Note that the same parts as in FIG. 6 are given the same reference numerals, and detailed explanation thereof will be omitted.

FIG. 1 is a configuration diagram of a gas laser oscillation device.

In the same figure, reference numeral 20 denotes a first discharge determining means, and this means 20 detects a change in the voltage level applied between the cathode 3 and anode 4 of the laser tube 1, which is an airtight container.
It has the function of determining whether the main discharge that occurs between the two is a glow discharge or an arc discharge. Specifically, it has a voltage divider 21 connected between the cathode 3 and anode 4 of the laser tube 1, and the divided output voltage S of the voltage divider 21 is applied to the comparator 22.
It is configured to be sent to the "+" input terminal of the . In addition,
The voltage divider 21 divides the voltage Vs from 1/1000 to 10,000.
The pressure is divided to 1/1 and output. On the other hand, a reference voltage generation circuit 23 is provided which divides the voltage of the power supply Vo to create a determination reference voltage Vk, and the determination reference voltage Vk created by this circuit 23 is sent to the "-" input terminal of the comparator 22. It has become. Thus, the comparator 22 sends a discharge determination signal ``a'' indicating whether the discharge is a glow discharge or an arc discharge to a discharge determination display 24 that includes a light emitting diode and a counter.

Further, 30 is a second radiation determining means, and this means 30 detects the change in the value of the current flowing between the cathode 3 and anode 4 of the laser tube 1, and the change in the current value generated between the cathode 3 and anode 4. It has the function of determining whether the main discharge is a glow discharge or an arc discharge. Specifically, a current transformer 31 is provided, the primary coil of the current transformer 31 is connected between the anode 4 and the high voltage power supply 9, and the secondary coil is connected to the comparator via a resistor 32. It is connected to the "+" input terminal of No. 33. Therefore, the current 1p detected by the current transformer 31 is applied to the voltage V by the resistor 32.
It is now converted to f. - It's electric! Vo
A reference voltage generation circuit 34 is provided which divides the voltage to generate a determination reference voltage vh, and the determination reference voltage vh generated by this circuit 34 is sent to the "-" input terminal of the comparator 33.

Thus, the comparator 33 sends out a discharge determination signal vb indicating whether it is a glow discharge or an arc discharge to a discharge determination display 35 that includes a light emitting diode and a counter.

Next, the main discharge determination function of the apparatus configured as described above will be explained. A high voltage is applied between the cathode 3 and anode 4 of the laser tube 1, and a discharge is generated at each bin electrode 5, 6. This discharge creates a pre-ionization state between the cathode 3 and anode 4, and after this, When a main discharge occurs between the cathode 3 and the anode 4 and gas laser light is oscillated, the voltage generated between the cathode 3 and the anode 4 at the time of the main discharge is
The voltage p is divided by the voltage divider 21 and sent to the "+" input terminal of the comparator 22. The judgment reference voltage Vk is input to the "-" input terminal of the comparator 22, and therefore, the comparator 22 uses the result of level comparison between the output voltage VS of the voltage divider 21 and the judgment reference voltage Vk to judge the discharge. It is output as a signal ya. By the way, as shown in FIGS. 2 and 3, the voltage Vp between the cathode 3 and anode 4 changes to negative when a high voltage is applied between the cathode 3 and anode 4, and then changes to positive. change towards.

Then, a main discharge occurs when this voltage Vp changes from negative to positive. Here, if the main discharge is a glow discharge as shown in Fig. 2, the voltage level of the voltage VE) will fluctuate relatively greatly and contract, and if the main discharge is an arc discharge as shown in Fig. The voltage vp initially changes to negative, but then does not change significantly to positive and becomes approximately zero volts. Therefore, the comparator 22 sends the discharge determination signal va, which becomes high level in the case of glow discharge, to the discharge determination display 24. In this manner, the discharge determination display 24 indicates that glow discharge is occurring by causing the light emitting diode to emit light, and counts the number of occurrences of arc discharge using a counter.

On the other hand, when the main discharge occurs, the current summer p flowing between the cathode 3 and the anode 4 is shunted by a shunt 31 and then applied to a resistor 32 to form a voltage Vf.
and is sent to the "+" input terminal of the comparator 33.

The “-” input terminal of this comparator 33 has a judgment reference voltage vh
Therefore, the comparator 33 outputs the comparison result of the level between the voltage Vf and the determination reference voltage vh as the discharge determination signal vb. By the way, the change in the current Ip between the cathode 3 and the anode 4 changes to a negative value when a high voltage is applied between the cathode 3 and the anode 4, as shown in the fourth factor and FIG. Change towards the positive. Then, when this current 1p changes from negative to positive, a main discharge occurs. Here, if the main discharge is a glow discharge as shown in Figure 4, the current ID will hardly flow after the main discharge occurs, and if the main discharge is an arc discharge as shown in Figure 5, the current ID will be 1p. changes significantly from negative to positive. Therefore, the comparator 33 outputs the discharge determination signal vb, which becomes high level in the case of arc discharge, to the discharge determination display 35.
Send to. Thus, the discharge determination display 35 indicates that arc discharge has occurred by causing the light emitting diode to emit light, and counts the number of times arc discharge has occurred using a counter.

In this way, in the above embodiment, the main discharge is determined as a glow discharge by detecting changes in the voltage level applied between the cathode 3 and anode 4 of the laser tube 1 and changes in the current value flowing between the cathode 3 and anode 4. Since the voltage vp between the cathode 3 and the anode 4 and its current ip show fluctuations according to glow discharge and arc discharge, it is certain that the main discharge is glow discharge or arc discharge. It can be determined whether there is a discharge. Therefore, arc discharge can be reliably detected no matter where it occurs between the cathode 3 and the anode 4 as shown in FIG. 8(C).

Note that the present invention is not limited to the above-mentioned embodiment, and may be modified without departing from the spirit thereof. For example, in the above embodiment, both the first and second discharge determining means 20.30 are provided, but a configuration may also be adopted in which only one of these means 20.30 is provided to determine whether it is a glow discharge or an arc discharge. good.

Further, the discharge judgment display 24 uses a glow discharge to cause a light emitting diode to emit light, and the discharge judgment display 35 uses an arc discharge to make a light emitting diode emit light. The discharge determination display 24 may cause a light emitting diode to emit light by arc discharge, and the discharge determination display 35 may cause a light emitting diode to emit light by a negative discharge. Further, as shown in Fig. 6, a coil L is placed in the line through which the current Ip flows, the coil L detects the magnetic field generated by the electric current IIp, and the voltage signal is used to determine whether it is a glow discharge or an arc discharge. You may also do so.

[Effects of the Invention] As described in detail above, according to the present invention, a highly reliable gas laser oscillation device that can reliably detect arc discharge can be provided.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of a gas laser oscillation device according to the present invention, FIGS. 2 and 3 are diagrams for explaining the discharge determination effect due to voltage changes in the same device, and FIGS. Fig. 5 is a diagram for explaining the discharge judgment effect due to current changes in the same device, Fig. 6 is a configuration diagram of the gas laser oscillation device, Fig. 7 is a configuration diagram showing a modified example of the shunt, and Fig. 8
9 and 9 are diagrams for explaining the conventional device. 1... Laser tube, 3... Cathode, 4... Anode, 5.
6... Bin stacking, 7, 8... Peaking capacitor, 9... High voltage power supply, 20... First discharge determination means, 2
DESCRIPTION OF SYMBOLS 1... Voltage divider, 22... Comparator, 23... Reference voltage creation circuit, 24... Discharge judgment indicator, 30... Second discharge judgment means, 31... Shunter, 32 ···resistance,
33... Comparator, 34... Reference voltage creation circuit, 35
...Discharge judgment indicator. Foreign applicant's agent Patent attorney Takehiko Suzue Figure 7 Figure 6 Figure 8 (a) (b) (c) Figure 9

Claims (3)

[Claims] (1) A gas laser oscillator comprising a pre-ionization means for pre-ionizing the gas laser medium, which is provided in the vicinity of a cathode and an anode that are arranged opposite to each other inside an airtight container in which a gas laser medium is sealed and generates a main discharge, and pre-ionizes the gas laser medium. A change in the voltage level applied between the cathode and anode and/or a change in the current value flowing between the cathode and anode are detected to determine whether the discharge generated between the cathode and the anode is a glow discharge or an arc. A gas laser oscillation device characterized by comprising a discharge determining means for determining whether it is a discharge. (2) The discharge determination means connects a voltage divider between the cathode and the anode, and compares the output voltage of the voltage divider with a determination reference voltage to obtain a discharge determination signal. Gas laser oscillator. (3) The discharge determination means connects a shunt between the airtight container and the high-voltage power supply, converts the output of the shunt into a voltage, and then compares this voltage with a determination reference voltage to obtain a discharge determination signal. A gas laser oscillation device according to claim (1).