JPH04279076A - Gas laser device - Google Patents

Abstract

PURPOSE:To obtain laser light having a high average output by increasing the number of main discharging repeating times. CONSTITUTION:The cathode 2 and anode 3 constituting main electrodes are connected to a DC power source 11 through a main capacitor 12 and the waveform of the electric energy supplied to the main electrode from the power source 11 is formed by means of peaking capacitors 6. The capacitance of the main capacitor 12 is set smaller than those of the peaking capacitors 6 so as to prevent the main capacitor 12 from becoming parasitic at the time of main discharge.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention is a gas laser that generates laser light by exciting a gas laser medium sealed in a laser tube by a main discharge generated between a main electrode consisting of a cathode and an anode. Regarding the equipment.

0002

2. Description of the Related Art It is known that gas laser devices include TEACO2 lasers and excimer lasers that emit laser light in a direction perpendicular to the discharge direction. These gas laser devices are often required to operate at high repetition rates in order to increase the average output.

Conventionally, such gas laser devices have a laser tube in which a gas laser medium is enclosed. Inside this laser tube, a cathode and an anode forming a main electrode are placed facing each other. This main electrode is connected to a DC power source via a main capacitor.

A plurality of sets of pre-ionization electrodes each consisting of a pair of pin electrodes with their tips facing each other are arranged in the vicinity of the main electrode within the laser tube. A peaking capacitor is connected to this preionization electrode. The electrical energy stored in the main capacitor can be transferred to this peaking capacitor by operating a switching element.

In a gas laser device having such a configuration, when a trigger signal is input to the switching element, the electrical energy stored in the main capacitor is transferred to the peaking capacitor, and a discharge occurs in the pre-ionization electrode. Occur. The discharge generates ultraviolet rays and pre-ionizes the discharge space between the cathode and anode of the main electrode. As preliminary ionization progresses in the discharge space, a main discharge is ignited between the cathode and the anode. This excites the gas laser medium and generates laser light.

During the main discharge, a large amount of electrical energy is injected into the main electrode, so many products such as metal vapor and halides are generated in the discharge space. When the next main discharge is ignited with the product remaining in the discharge space,
Since the main discharge becomes unstable due to the occurrence of arc discharge, etc., the output of the laser beam may decrease or the laser beam may stop. Therefore, a blower is usually used to circulate the gas laser medium to quickly remove the products from the discharge space.

[0007] Unless the flow rate of the gas laser medium is increased as the number of repetitions of the main discharge is increased, the product cannot be reliably removed from the discharge space. On the other hand, since the electrical energy injected into the blower is proportional to the cube of the gas flow velocity, the flow velocity of the gas laser medium must be lowered as much as possible in order to improve the operating efficiency of the gas laser device.

[0008] Since it is difficult to satisfy these contradictory conditions, measures such as making the flow of the gas laser medium uniform have been taken, but at present, fully satisfactory results have not been obtained. It is.

By the way, in conventional gas laser devices, the capacity of the main capacitor that supplies electrical energy for main discharge to the main electrode is set to be larger than the capacity of the peaking capacitor. As a result, electrical energy is supplied to the main electrode relatively slowly not only from the peaking capacitor during main discharge but also from the main capacitor, making it possible to obtain high output laser light. can.

However, when a high-output laser beam is obtained in this manner, the time required for each main discharge from ignition to completion becomes relatively long. Therefore, if you want to increase the number of repetitions of the main discharge to obtain a higher output laser beam, as described above, the products generated in the discharge space before the next main discharge are ignited should be removed. It will not be possible to remove it reliably. Therefore, in order to obtain a high average laser output by increasing the number of repetitions of the main discharge, the main discharge must be terminated in a short time.

[0011]

[Problems to be Solved by the Invention] In this way, in conventional gas laser devices, in order to obtain high output, the capacitance of the main capacitor was made larger than the capacitance of the peaking capacitor. It was difficult to increase the output power and obtain a higher average output.

The present invention was made based on the above circumstances, and its purpose is to shorten the main discharge time, increase the number of repetitions, and produce a laser beam with a high average output. An object of the present invention is to provide a gas laser device that can be obtained.

[0013]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a laser tube in which a gas laser medium is sealed, a blower for circulating the gas laser medium in the laser tube, A main electrode consisting of a cathode and an anode arranged opposite to each other in the laser tube, a DC power supply that supplies electrical energy to the main electrode via a main capacitor, and a DC power supply that supplies electrical energy to the main electrode from the DC power supply. The electrical energy transferred from the main capacitor to the peaking capacitor prior to the main discharge occurring in the discharge space between the cathode and the anode of the main electrode is used to shape the waveform of the electrical energy. A pre-ionization electrode is provided for pre-ionizing the discharge space, and the capacitance of the main capacitor is set to be smaller than the capacitance of the peaking capacitor.

[0014]

[Operation] According to the above configuration, since the capacitance of the main capacitor is smaller than the capacitance of the peaking capacitor, the contribution of the main capacitor during main discharge is eliminated, so the main discharge time is shortened and the number of repetitions is reduced. It can be made higher.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The gas laser device shown in FIG. 1 has a laser tube 1 in which a gas laser medium is sealed. Inside the laser tube 1, a cathode 2 and an anode 3 forming a main electrode are arranged facing each other and spaced apart in the vertical direction. Upper pin electrodes 4 are disposed on both sides of the cathode 2, and lower pin electrodes 5 are disposed on both sides of the anode 3, with their upper ends facing the lower ends of the upper pin electrodes 4. A peaking capacitor 6 is connected to the upper pin electrode 4.

Inside the laser tube 1 is a blower 8 that circulates the gas laser medium in the discharge space 7 between the cathode 2 and the anode 3 as shown by the arrow, and a blower 8 that cools the circulating gas laser medium. A heat exchanger 9 is provided for this purpose.

The cathode 2 and the upper pin electrode 4 are connected to the DC power supply 1.
Connected to the negative side of 1 via the main capacitor 12,
The anode 3 and the lower pin electrode 5 are connected to the positive side. A thyratron 13 as a switching element is connected between the minus side and the plus side of the DC power supply 11, and a coil 14 is installed in parallel with this thyratron 13.
is connected.

The capacitance of the peaking capacitor 6 is Cp.
If the capacitance of the main capacitor 12 is Cs, the capacitance Cp of the main capacitor 12 is set smaller than the capacitance Cp of the peaking capacitor 6. In this embodiment, the capacitance Cp of the main capacitor 12 and the peak
The capacitance ratio of the King capacitor 6 is [Cp /Cs ≦2
/3].

In the gas laser device configured as described above, the main capacitor 12 is charged via the coil 14. When a trigger signal is input to the thyratron 13, the electrical energy stored in the main capacitor 12 is transferred to the peaking capacitor 6 because the thyratron 13 becomes conductive. As a result, ultraviolet light is generated by arc discharge between the upper pin electrode 4 and the lower pin electrode 5, and the ultraviolet light pre-ionizes the discharge space 7.

As the preliminary ionization of the discharge space 7 progresses, a main discharge is ignited between the cathode 2 and the anode 3 by the electrical energy transferred from the main capacitor 12 to the peaking capacitor 6. As a result, the gas laser medium circulated through the discharge space 7 by the blower 8 is excited, and laser light is output in a direction perpendicular to the direction of the main discharge.

The capacitance Cs of the main capacitor 12 is
The capacitance of the King capacitor Cp is set smaller than that of the King capacitor Cp. Therefore, the electrical energy stored in the main capacitor 12 before the main discharge is ignited is transferred to the thyratron 1.
When capacitor 3 becomes conductive, all of the capacitor 3 is transferred to peaking capacitor 6. As a result, during the main discharge, the main capacitor 12 makes no contribution at all, so the laser output decreases.

This state is shown in FIG. That is, in the figure, curves A and A' are for the conventional case, and curve B is for the present invention. Curve A is for the case where the capacitance Cs of the main capacitor 12 is 1.2 times the capacitance of the peaking capacitor Cp, and curve A' is for the case where Cs=Cp. Curve B is Cs
/Cp = 2/3, and it can be seen that in the case of curve B, the laser output decreases and a high applied voltage is required.

However, during the main discharge, the main capacitor 1
By eliminating the contribution of 2, the main discharge ends in a short time. Therefore, it is possible to speed up the repetitive operation of the main discharge without increasing the flow rate of the gas laser medium. In other words, if the gas flow rate is the same, the number of repetitions of the main discharge can be sufficiently increased compared to the conventional method.

FIG. 2 shows the relationship between the gas flow rate and the number of repetitions of main discharge, in which curve A is for the conventional case and curve B is for the present invention. As can be seen from this figure, when the main discharge is ignited at the same number of repetitions, compared to the conventional curve A,
The invention of curve B requires a lower gas flow rate.

Furthermore, as shown in FIG. 4, when the main discharge is set to a certain number of repetitions N or more, the case of the present invention shown by curve B is better than the conventional case shown by curve A in the same figure, even if the number of repetitions is the same. It was confirmed that the average laser output was increased. That is, when the number of repetitions of the main discharge is increased, products generated by the main discharge can be easily removed from the discharge space 7 according to the structure of the present invention in which the main discharge time is short. However, in the conventional configuration where the main discharge time is long, the next main discharge will be ignited before the main discharge is sufficiently removed. Therefore, when the number of repetitions of the main discharge is increased, in the conventional configuration, the main discharge between the cathode 2 and the anode 3 becomes an arc discharge due to the influence of the products, which is thought to cause a decrease in output. .

[0026]

Effects of the Invention As described above, in this invention, since the capacitance of the main capacitor is set smaller than the capacitance of the peaking capacitor, the main capacitor no longer contributes to the main discharge. Can be shortened. Therefore, although the laser output per unit pulse decreases, the average laser output when the number of repetitions exceeds a certain value can be increased. In other words, it is possible to provide a gas laser device suitable for obtaining a high average laser output through highly repeated main discharges.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the overall configuration of an embodiment of the present invention;

FIG. 2 is a graph showing the relationship between gas flow rate and repetition rate.

FIG. 3 is a graph showing the relationship between laser output and applied voltage when changing the capacitance ratio between the main capacitor and the peaking capacitor.

FIG. 4 is a graph showing the relationship between average laser output and number of repetitions.

[Explanation of symbols]

1...Laser tube, 2...Cathode (main electrode), 3...Anode (main electrode), 4...Upper pin electrode (preliminary ionization electrode), 5...Lower pin electrode (preliminary ionization electrode), 6...Peaking capacitor, 7
...Discharge space part, 8...Blower, 11...DC power supply, 12...Main capacitor.

Claims (1)

[Claims] Claim 1: A laser tube in which a gas laser medium is sealed, a blower that circulates the gas laser medium within the laser tube, and a cathode and an anode that are disposed facing each other within the laser tube. A main electrode consisting of a DC power source that supplies electrical energy to the main electrode via a main capacitor, and a peaking capacitor that shapes the waveform of the electrical energy supplied from the DC power source to the main electrode. , a pre-ionization electrode that pre-ionizes the discharge space with electrical energy transferred from the main capacitor to the peaking capacitor prior to the main discharge occurring in the discharge space between the cathode and the anode of the main electrode. , the capacitance of the main capacitor above is
A gas laser device characterized by being set smaller than the capacitance of a King capacitor.