JPH09293914A - Gas laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas laser in which the life of electrodes for preliminary ionization is increased and the reliability of a laser tube is improved and the life of the laser tube is increased by reducing the contamination in the laser tube. SOLUTION: A gas laser excites gas to generate laser light by discharge between a pair of main discharge electrodes. Prior to the discharge between a pair of main discharge electrodes 2 and 3, a pulse high voltage is applied to fine lines 11 which are insulated and strung in proximity of the main discharge electrodes 3 to generate pulse streamer discharge. Ultraviolet rays generated by discharge are applied to gas between the main discharge electrodes 2 and 3 to cause preliminary ionization of the gas.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a gas laser device,
In particular, it relates to preliminary ionization in a discharge excitation type gas laser device.

[0002]

2. Description of the Related Art A gas laser device such as an excimer laser device has a rare gas (Ar, Kr, Xe, etc.) and a halogen gas (F, F,
A pair of main discharge electrodes 2 in a mixed gas atmosphere of Cl, etc.,
3, a preliminary ionization pin 4 and a secondary capacitor 5 are arranged, and a predetermined high voltage is applied between the pair of main discharge electrodes 2 and 3 to discharge and excite the mixed gas to emit a pulse laser in the ultraviolet region. It is configured to oscillate (excimer laser).

That is, in FIG. 6, 6 is a high voltage power source,
Reference numeral 7 is a primary capacitor, 8 is a switching element such as a thyratron that performs high-speed switching operation, 9 is a charging coil, and the high-voltage power supply 6 turns the primary coil 7 into a charging coil 9 when the switching element 8 is off. 1 when the switching element 8 is driven on by being charged via
The charge charged in the secondary capacitor 7 is transferred to the secondary capacitor 5 via the preionization pin 4.

When a current flows through the preionization pin 4 due to this transition, an arc discharge is formed at the preionization pin 4. Ultraviolet rays radiated from the arc discharge are irradiated between the main discharge electrodes 2 and 3, and preliminary ionization of the laser gas is performed. Then, the voltage of the secondary capacitor 5 rises, and when it reaches a predetermined high voltage, a current flows between the main discharge electrodes 2 and 3, and a uniform glow discharge is formed by this current to cause laser oscillation. Note that 10 is the line distributed reactance.

[0005]

By the way, in the preionization system in which the preionization is performed by the arc discharge as described above, the metal of the electrode material forming the preionization pins 4 is largely sputtered by the arc discharge, and its consumption is severe and the life is long. However, there is a problem in that the inside of the laser tube 1 is contaminated by the sputtered particles of the electrode material metal and the laser oscillation is adversely affected.

It is possible to use corona discharge as a preionization method for solving this problem, but in the corona preionization method, a large current cannot be obtained because discharge is performed through a dielectric, and the discharge state is dot-like. Alternatively, since light is emitted linearly, there is a problem that the amount of ultraviolet rays necessary for preionization is small and efficient laser oscillation cannot be expected.

The present invention has been made in view of the above problems, and it is possible to extend the life of the preionization electrode for performing preionization in this type of gas laser device, reduce the contamination inside the laser tube, and reduce the An object of the present invention is to provide a gas laser device capable of improving the reliability of the tube and extending the life of the laser tube.

[0008]

The above object of the present invention can be achieved by the following items (1) to (3).

(1) In a gas laser device which excites gas by a discharge between a pair of main discharge electrodes to generate laser light, a pulse voltage is applied along the vicinity of any one of the pair of main discharge electrodes. A gas laser device characterized in that a fine wire for generating a streamer discharge is arranged, and ultraviolet rays generated by the pulse streamer discharge are irradiated to the gas between the main discharge electrodes to preionize the gas.

(2) In a gas laser device which excites gas by a discharge between a pair of main discharge electrodes to generate laser light, a cylindrical electrode having an opening between the main discharge electrodes and a central part of the cylindrical electrode. An electrode pair provided with a thin wire electrode is arranged along the vicinity of one of the main discharge electrodes of the pair, and a pulse voltage is applied to the electrode pair to generate a pulse streamer discharge in the thin wire electrode. And let
A gas laser device characterized in that the gas between the main discharge electrodes is irradiated with ultraviolet rays generated by the pulse streamer discharge to preionize the gas.

(3) In a gas laser device which excites a gas by a discharge between a pair of main discharge electrodes to generate laser light, a flat electrode and a thin line-shaped wire which are arranged to face the central portion of the flat electrode. An electrode pair provided with an electrode is arranged along the vicinity of any one of the pair of main discharge electrodes, and a pulse voltage is applied to the electrode pair to generate pulse streamer discharge in the thin wire electrode, A gas laser device characterized in that the gas between the main discharge electrodes is irradiated with ultraviolet rays generated by the pulse streamer discharge to preionize the gas.

According to the above feature of the present invention, a pair of a fine wire or a fine wire-like electrode arranged along the vicinity of the main discharge electrode and a peripheral member of the fine wire or the fine wire-like electrode, a cylindrical electrode or a flat plate-like electrode is formed. A long pulse streamer discharge transmission line is formed by the electrodes, and a pulse high voltage having an extremely short pulse width is applied to the transmission line, and a pulse streamer discharge accompanied by light emission is formed on the entire surface of the thin line or thin line electrode.

Unlike arc discharge, this pulse streamer discharge does not raise the temperature of the electrode because electrons are supplied by an electric field. Therefore, the consumption of the electrode is extremely small, and since it does not occur through the dielectric, a large current is generated. Since electricity can be supplied and a uniform discharge can be formed in a large volume, the amount of ultraviolet rays generated can be increased, and the preliminary ionization of the gas interposed between the main discharge electrodes can be effectively performed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A gas laser device according to the present invention will be described below with reference to the drawings. The same parts are denoted by the same reference numerals throughout the drawings, and redundant description will be omitted. FIG. 1 is a circuit configuration diagram of an example of a gas laser device according to the present invention, 2 is a main discharge electrode, 3 is a ground potential side main discharge electrode,
Reference numeral 5 is a secondary capacitor, 6 is a high voltage power supply, 7 is a primary capacitor, 8 is a switching element such as a thyratron for performing high speed switching operation, 9 is a charging coil, and these are gas lasers described with reference to FIG. Functions the same as the device.

Reference numeral 11 denotes a thin wire, which may be either of the main discharge electrodes 2 and 3 as shown in the plan view of the electrode portion of FIG. 3, but in this example, it is grounded at a position near the ground potential side main discharge electrode 3. It is stretched along both outer circumferences of the potential side main discharge electrode 3 in the longitudinal direction and is at the same potential (ground potential) as the ground potential side main discharge electrode 3 such as the thin wire 11 and the tube wall around the thin wire 11. The members are adapted to form a pulse streamer discharge transmission line.

As shown in FIG. 1, one end or both ends of each thin wire 11 arranged on both sides of the ground potential side main discharge electrode 3 in the longitudinal direction is connected to one end of the switching element 8 as shown in FIG. A coil (inductor) 15 whose end is connected to the other end of the switching element 8 and a capacitor 1
The parallel circuit of 2 and the coil 16, the capacitor 13, and the resistor 14 is connected in series, and is connected to the connection point of the parallel circuit of the capacitor 12, the capacitor 13, and the resistor 14.

In the circuit configured as described above, when the switching element 8 is closed, charge transfer from the primary capacitor 7 to the secondary capacitor 5 is started, and at the same time, a pulse high voltage is applied to the thin wire 11, and this pulse high voltage is applied. Propagates through the pulse streamer discharge transmission line along the thin wire 11, and a negative pulse streamer discharge starts on the thin wire 11.
This pulse streamer discharge is started prior to the discharge between the main discharge electrodes 2 and 3, and pre-ionizes the gas interposed between the main discharge electrodes 2 and 3.

The inductor 1 inserted in the series circuit
Reference numeral 5 is for changing the rise time of the pulse voltage applied to the thin wire 11, and the optimum rise time can be set. The capacitor 13 is for adjusting the pulse voltage value applied to the thin wire 11, and the resistor 14 is for adjusting the pulse width applied to the thin wire 11.

The circuit configuration of this example has a switching element 8
The high-speed repeated opening and closing is used to apply a pulse high voltage with a very short pulse width to the thin wire 11, and a pulse streamer discharge is applied to the discharge circuit for discharging between the main discharge electrodes 2 and 3 and the thin wire 11. The switching element 8 is also used to start both circuits of the pre-ionization circuit, and the entire circuit is simplified.

FIG. 2 is a circuit diagram of another example of the gas laser device according to the present invention. In the preionization circuit for performing pulse streamer discharge, a high voltage pulse generator 24 is provided, and the main discharge electrodes 2 and 3 are connected. The discharge circuit for discharging is separately provided, and the trigger pulser 22 and the delay pulser 23 can arbitrarily set the timing of preionization.

By allowing the timing of preionization to be set arbitrarily in this manner, preionization can be performed at a more optimal timing. The generation of the pulse streamer discharge, the discharge between the main discharge electrodes 2 and 3, and the disposition of the thin wire 11 with respect to the ground potential side main discharge electrode 3 are the same as those in the example of FIG.

In the example shown in FIGS. 1 and 2, a thin wire 11 and a thin wire 11 are insulated and stretched along the outer periphery of the ground potential side main discharge electrode 3 at a position near the ground potential side main discharge electrode 3. A member having the same potential (ground potential) as the main discharge electrode 3 on the ground potential side, such as the peripheral wall of the tube, forms the pulse streamer discharge transmission line. 5 can be configured as shown in the front view of the electrode section.

That is, the pulse streamer discharge transmission line shown in FIG. 4 has a thin line-shaped electrode 31 arranged along the ground potential side main discharge electrode 3 similarly to the thin line 11 described with reference to FIG. The electrode 31 is located at the center, and is configured by a pair with a cylindrical electrode 32 surrounding the electrode 31,
Opening 33 in which the portion of the cylindrical electrode 32 facing between the main discharge electrodes 2 and 3 has a mesh shape (not necessarily required)
Are formed.

One or both ends of the electrode 31 are connected to the preionization circuit in the same manner as the thin wire 11 shown in FIG. 1 or 2, and the cylindrical electrode 32 is grounded. Also in the pulse streamer discharge transmission line configured as described above, the pulse streamer discharge is formed in the electrode 31 as in the example shown in FIG. 1 or 2, and the ultraviolet rays passing through the opening 33 of the cylindrical electrode 32 are discharged to the main discharge electrode 2. The gas interposed between the three is preionized. In this case, if the inner surface of the cylindrical electrode 32 is coated with a UV reflection coat, the efficiency of use of UV rays can be further improved.

The pulse streamer discharge transmission line shown in FIG. 5 has a thin line-shaped electrode 41 arranged along the ground potential side main discharge electrode 3 similarly to the thin line 11 described with reference to FIG.
And a flat plate-shaped electrode 42, which is arranged so as to face the electrode 41 at the center thereof.

One end or both ends of the electrode 41 are connected to the preionization circuit in the same manner as the thin wire 11 shown in FIG. 1 or 2, and the plate electrode 42 is grounded. The pulse streamer discharge transmission line configured in this way is also shown in FIG.
Alternatively, similarly to the example shown in FIG. 2, a pulse streamer discharge is formed on the electrode 41, and the ultraviolet rays formed by the discharge preionize the gas interposed between the main discharge electrodes 2 and 3.

In the gas laser device in each of the above examples,
The pulse applied to the pulse streamer discharge transmission line has a pulse width of 10 ns to 5 μs and a voltage of 5 KV to 50 KV, and the thin wire and the thin wire electrode have a diameter of 0.
It is made of metal of 1 mm to 5 mm, and its material is not corroded by laser gas, for example, W, Mo, Ni, Cr, Cu, A
It is formed of 1, Fe, Ta, Au, Pt, or an alloy thereof such as SUS or brass.

[0028]

As described in detail above, according to the present invention,
Since preionization in the gas laser device is performed by pulse streamer discharge, it is possible to prolong the life of the preionization electrode, reduce the contamination inside the laser tube, improve the reliability of the laser tube, and improve the life of the laser tube. It can be extended. Further, uniform and strong ultraviolet rays can be used for preionization, and efficient laser oscillation can be achieved.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of an example of a gas laser device according to the present invention.

FIG. 2 is a circuit configuration diagram of another example of the gas laser device according to the present invention.

FIG. 3 is a plan view showing an arrangement configuration of electrodes of a gas laser device according to the present invention.

FIG. 4 is a front view showing the configuration of another example of the corona transmission line of the gas laser device according to the present invention.

FIG. 5 is a front view showing the configuration of still another example of the corona transmission line of the gas laser device according to the present invention.

FIG. 6 is a configuration diagram of an example of a conventional gas laser device.

[Explanation of symbols]

 1 Laser Tube 2, 3 Main Discharge Electrode 5 Secondary Capacitor 6 High Voltage Power Supply 7 Primary Capacitor 8 Switching Element 9 Charging Coil 11 Fine Wire (Preliminary Ionizing Electrode) 12, 13 Capacitor 14 Resistor 15, 16 Coil 22 Trigger Pulser 23 Delay Pulser 24 High voltage pulse generator 31, 41 Fine wire electrode (pre-ionization electrode) 32 Cylindrical electrode 42 Flat plate electrode

Claims (3)

[Claims] 1. A gas laser device for exciting a gas by a discharge between a pair of main discharge electrodes to generate laser light,
A thin wire that generates a pulse streamer discharge by applying a pulse voltage is arranged along the vicinity of one of the pair of main discharge electrodes, and ultraviolet rays generated by the pulse streamer discharge are applied to the gas between the main discharge electrodes. A gas laser device characterized in that the gas is preionized. 2. A gas laser device for generating a laser beam by exciting a gas by a discharge between a pair of main discharge electrodes,
An electrode pair provided with a cylindrical electrode having an opening toward the main discharge electrodes and a thin line-shaped electrode at the center of the cylindrical electrode is arranged along the vicinity of one of the pair of main discharge electrodes, A pulse voltage is applied to the electrode pair to generate a pulse streamer discharge in the thin wire electrodes, and ultraviolet rays generated by the pulse streamer discharge are applied to the gas between the main discharge electrodes to pre-ionize the gas. A gas laser device characterized by the following. 3. A gas laser device for generating a laser beam by exciting a gas by a discharge between a pair of main discharge electrodes,
An electrode pair provided with a flat plate-shaped electrode and a fine wire-shaped electrode arranged to face the central portion of the flat plate-shaped electrode is arranged along the vicinity of one of the main discharge electrodes of the pair, and the electrode pair is arranged. A pulse voltage is applied to generate a pulse streamer discharge in the thin wire electrode, and ultraviolet rays generated by the pulse streamer discharge are applied to the gas between the main discharge electrodes to pre-ionize the gas. A gas laser device.