JPS6321883A - Pulse laser oscillator - Google Patents

Abstract

PURPOSE:To obtain a high efficiency and high quality beam with high output by providing a plurality of holes in a second main electrode, and providing an ultraviolet light generation source for pre-ionizing laser gas between first and second electrodes on the back surface. CONSTITUTION:Electrons are uniformly supplied to the whole surface of a first main electrode 7 by a corona discharge 16 started between the first main electrode 7 and an auxiliary electrode 15 by the charging voltage of a capacitor 3. A second trigger signal is fed at a certain delay to a pre-ionization discharge circuit 4, an arc discharge 8 is performed between the second main electrode 17 and a pin electrode 5, and an ultraviolet light 9 is generated to pre-ionize the laser gas of a discharge exciter 11. Since the discharge path is uniformly weak-ionized by the light 9, even if the interval of the first and second electrodes 7 and 17 is large, it is not converged, but the laser is enhanced in its output, efficiency and quality of beam and simplified by large sectional uniformity main discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pulsed laser oscillator, and particularly to a laterally pumped pulsed laser oscillator.

[Conventional technology]

Figure 6 shows, for example, a magazine (IEEE Journal of
Quantum Electronics, @QE
This is a block diagram showing the configuration of a conventional lateral excitation type pulsed laser oscillator described in Vol. 9, No. 2 @ pages 236 to 243 (1973), especially for excimer lasers (e.g. EVA ArF, KrF.

XeF *Xe(J3) *Nitrogen laser, TEA
This is an example of a pulsed laser oscillator used in CO, laser, etc.

In the figure, C1) is a trigger control circuit that issues two trigger signals at different time intervals, (2) is the first circuit, which is a pulse charging circuit for main discharge, and (3) stores energy for causing main discharge. The capacitor (4) is a second circuit that supplies energy for pre-ionization performed prior to the main discharge, and is a discharge circuit for pre-ionization, and the capacitor (5) is a plurality of capacitors, for example four, for causing a discharge for pre-ionization. pin electrode, (6
) is an inductance for uniformly flowing the energy supplied from the pre-ionization discharge circuit (4) to a plurality of pin electrodes, (7) is a first piezoelectric electrode having a plurality of holes, for example, four holes, ( 8) is an arc discharge for preliminary ionization performed between the pin electrode (5) and the first piezo electrode (7), and (9) is the ultraviolet light generated by the arc discharge (8). 0Q is the second main electrode, αη is a discharge excitation part where the laser is excited by the main discharge, (2) is the laser oscillation optical axis, and (to) is the laser housing.

Next, the operation will be explained. Laser scum is enclosed within the laser housing. A first trigger signal is sent from the trigger control circuit (1) to the main discharge pulse charging circuit (2), and charging of the capacitor (3) is started. At this time, the charging voltage of the capacitor (3) changes to the first main electrode (7).
) and the second main electrode αq. A second trigger signal is sent from the trigger control circuit (1) to the pre-ionization discharge circuit (4) after a fixed time delay from the @1 trigger signal. As a result, a pulsed high voltage is applied between the pin electrode (5) and the first main electrode (7), and an arc discharge (9) occurs between the pin electrode (5) and the first main electrode (7).
is started. A large number of pin electrodes (5) are installed at equal intervals on the back of the first main electrode (7), but the inductance (
6), the current due to the arc discharge (8) flows equally through each pin electrode (51).

Here, the arc discharge (8) generates ultraviolet light (9).

This ultraviolet light (9) passes through a large number of openings provided in the first main electrode (7) and passes through the first main electrode (7). @2 Voltage electrode (7), 00 is uniformly irradiated, and the laser gas between them is uniformly weakly ionized (with a particle density ηQ = 106 ~ 1o8z7t-i)
shall be. At this time, the charging voltage of the capacitor (3) is
I! 1. The discharge starting voltage between the @2 piezo electrode (1) and 00 is reached, and the charge stored in the capacitor (3) is suddenly @1
．． @2 main electrode f7), (10), and a pulse discharge is formed in the discharge excitation part αυ.This discharge is a uniform discharge because the discharge excitation part 0υ is brought into a uniform preliminary ionization state in advance. This excites the laser beam in the laser gas, and a laser beam is emitted in the direction of the optical axis due to stimulated emission.

Now, the pre-ionization method using ultraviolet light from the back of the electrode, as shown in the example above, enables uniform discharge excitation over a large discharge cross section, so it is extremely effective for increasing the output, efficiency, and compactness of laser equipment. It was a great method. However, the energy required for preionization is
It is 10 to 20 times larger than that of the main discharge. Therefore, it is industrially useful.

In high-repetition devices that oscillate more than 100 times per second, deterioration of electrodes and laser gas due to arc radiation has become a problem.

Figure 7 is a block diagram showing an example of a pre-ionization method used to solve this problem. , a dielectric material such as ceramic, (G) is an auxiliary electrode placed opposite to the @1 main pole (7) with a dielectric material α interposed therebetween, and α is the first piezoelectric $1 (7). The dielectric material 0 in the opening of
This is a corona discharge that occurs on the 4th surface.

First, the electrode system is composed of the @2 voltage electrode (1), the αQ1 electric body α, and the auxiliary electrode (G).

Next, I will explain how it works. The main discharge pulse charging circuit (2) pulse-charges the capacitor (3). Since the dielectric α4 is inserted between the first main electrode (7) and the auxiliary electrode (G), this forms a kind of capacitor, and when the capacitor (3) starts charging, the A voltage corresponding to the voltage is applied between both electrodes, and the dielectric α
The corona discharge αQ becomes extremely strong on the surface of the main electrode (7), and the laser gas around the opening of the main electrode (7) becomes uniformly weakly ionized. Charging capacitor (3) at the same time! ζ From this, the charging voltage is applied between the @1 main electrode (7) and the second main electrode GO, and eventually reaches the discharge starting voltage. Therefore, when the H starting voltage (H) is reached, the charge stored in the capacitor (3) is instantly transferred to the first piezo electrode (1), @2 main 7! pole (10
I'! i, and a pulse discharge is formed in the discharge excitation part αυ. @1 When the main electrode (7) is set as a cathode, corona discharge α0 is used in advance! ! 1 Lord (17
) Since electrons are uniformly supplied over the entire surface of C,
With these electrons as the nucleus, a uniform pulse discharge is generated over the entire electrode surface. The laser vibration in the laser gas is excited by this radiation, and a laser beam is emitted in the direction of the optical axis (9) by stimulated emission.

In the method shown here, since the auxiliary discharge is a corona discharge via the dielectric (4), uniform preliminary ionization can be performed even in the case of a wide discharge width due to the balance effect of the dielectric. In this case, the energy consumed for the auxiliary discharge is small compared to the case where arc discharge is used, and the problems of deterioration of the piezo electrode and laser gas are reduced.

[Problem to be solved by the invention]

However, with conventional pulsed laser oscillators.

@ As shown in Figure 8, in an attempt to obtain a large discharge cross section @
1. @2 main 'IIL pole (1), if the interval between α0 is widened, I! Although a wide discharge is obtained on the surface of the l main electrode (7), the discharge converges as it approaches the @2 main electrode αQ, and the uniformity of the discharge is lost. As a result, the symmetry and uniformity of the oscillation mode of the laser are lost, and the excitation efficiency is reduced due to non-uniform discharge. The convergence of discharge tends to occur more significantly as the applied voltage is lower.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide a pulsed laser oscillator that has high output, high efficiency, and can provide a high-quality beam.

[Means for solving problems]

The pulse laser oscillator according to the present invention includes a first main electrode and a second main electrode each having a plurality of openings arranged to face each other in a laser gas, and arranged on the back surface of the first main electrode. Electrode system consisting of a dielectric and a 1Jrl main electrode and an auxiliary electrode facing each other with the dielectric interposed therebetween, @L, @2
@1 circuit that applies the cardiac interelectrode voltage between the main electrodes, and the voltage is applied between the auxiliary electrode and the first piezoelectric electrode! In a pulsed laser oscillator equipped with a g2 circuit, the @2 main electrode has a plurality of openings, and a first . @Equipped with an ultraviolet light generation source that pre-ionizes the laser gas between the two electrodes.

[Effect]

The piezo electrode of the pulsed laser oscillator in this invention has a first
The uniform electrons supplied by the corona discharge on the back surface of the piezo electrode grow as nuclei, and the pre-ionization effect of the discharge excitation part due to the weak ultraviolet rays on the back surface of the second main electrode causes the second main electrode to grow without convergence. reach.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. @1
In the figure, αη is a second main electrode having a large number of openings for transmitting ultraviolet light (9).

In this embodiment, the pin electrode (5) used as the auxiliary electrode in Fig. @6 is provided on the back surface of the second main electrode to constitute an ultraviolet generation source.

Operation 1 according to an embodiment of the present invention is as follows. A first trigger signal from the trigger control circuit (1) is sent to the main discharge pulse charging circuit (2).

Charging of the capacitor (3) begins. At the same time, this charging voltage is applied between the @1 main electrode (7) and the auxiliary electrode αQ.

Corona discharge α0 begins. This corona discharge αe causes the capacitor (3) to pass through the charging period ζ, and the first main electrode (7
) electrons are uniformly supplied to the entire surface. After some delay from the trigger signal @1, the trigger signal @2 is sent from the trigger control circuit (1) to the pre-ionization discharge circuit (
4) A second main electrode (17
) and the pin electrode (5). Ultraviolet light (9) is generated from this, and @2 piezo electrode a
The laser gas in the discharge excitation part αυ is pre-ionized by passing through the opening of η. @1. When the voltage between the second piezo electrodes (7) and (19 reaches the discharge starting voltage, @1
Electrons uniformly supplied to the surface of the main electrode (7) cause an electron avalanche as nuclei, and a discharge path is formed between the second piezoelectrodes αη. At this time, since the discharge path has been uniformly and weakly ionized in advance by ultraviolet light (9), @1. @2 main electric current i+7), even when the interval between α forces is large, the main discharge does not converge, and a uniform main discharge is obtained over the discharge excitation part (b) with a large cross section. Achieving large cross-section uniform discharge (this makes it possible to achieve high output, high efficiency, high beam quality, and compactness of lasers.

Incidentally, the arc discharge (3) in this example is supplementary to the corona discharge αO, and the input energy can be suppressed to about 115 to 1/10 compared to the case of preliminary ionization using ultraviolet light alone. Therefore, problems of electrode deterioration and laser gas deterioration caused by arc discharge (8) are almost eliminated.

In the above embodiment, an arc group 1t (8) was generated between the second piezoelectric electrode αη having a large number of openings and the pin electrode (5), and ultraviolet light (9) was generated. However, Fig. 2.

and a sectional view thereof taken along line 11. @3 As shown in Figure 3, a plurality of flat plates polarized α9 are arranged at equal intervals like stepping stones on the insulating substrate port 1 installed on the back side of the second main electrode aη, for example, on an Evosen substrate, and The backing electrode is installed so as to face the vL pole Q9, and a high pulse voltage is applied between the stepping stone-shaped @pole α9 and the backing polarization ω, along the III-III line cross section. Creeping radiation @24D
may be caused to generate ultraviolet light (9). In this method, the second piezoelectrode αη does not participate in preliminary discharge;
There is no problem with the accompanying deterioration of the electrodes.Furthermore, the manufacturing process can be simplified by depositing copper on the epoxy substrate G and then etching it to form the flat plate electrodes α9 at equal intervals.

Figure 4 and its V-Vm cross section.

As shown in FIG. 5, the second piezoelectric electrode Q'? ) Line up the pipe with insulating material on the back and on top of this pipe.

(2) A plurality of needle-like electrodes are installed at regular intervals along the -v line cross section, and a lining electric wire is also installed in the hollow part of the pipe.

Even if a pulsed high voltage is applied between the needle electrode and the backing ta to cause arc discharge and generate ultraviolet light (9), the same effect as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, an @l piezoelectrode having a plurality of openings disposed to face each other in the laser gas, a second piezoelectrode, and a second piezoelectrode disposed on the back surface of the first piezoelectrode. an electrode system consisting of a first piezoelectric electrode and an auxiliary electrode facing each other with the dielectric interposed therebetween; a first circuit for applying a pulse voltage between the second electrode; In a pulse laser oscillator equipped with a second circuit for applying a voltage between the electrode and the first main electrode, the second piezoelectric electrode has a plurality of openings, and the back surface thereof is connected to the first and second electrodes. Equipped with an ultraviolet light generation source that pre-ionizes the laser gas in between, preventing convergence of discharge and achieving high output and efficiency.

Moreover, it is possible to obtain a pulsed laser oscillator that outputs a high-quality beam.

[Brief explanation of drawings]

@ Figure 1 is a block diagram showing a pulsed laser oscillator according to one embodiment of the present invention, Figure 2 is an enlarged sectional view showing an ultraviolet light generation source according to another embodiment of the invention, and Figure 3 is Figure 2. FIG. 4 is an enlarged cross-sectional view showing an ultraviolet light generation source according to another embodiment of the present invention, and FIG. 5 is a cross-sectional view taken along line V-Va in FIG. 4. The sectional view, FIG. 6, and FIG. 7 are block diagrams showing conventional pulse laser oscillators, and FIG. 8 is! FIG. 8 is an explanatory diagram showing an enlarged view of the laser casing shown in FIG. 7; In the figure, (2) is the main discharge pulse charging circuit, (3)
is a capacitor, (4) is a pre-ionization discharge circuit, (5)
is a pin electrode, (7) is the first main electrode, (8) is an arc discharge, (9) is an ultraviolet light, α fathom is a dielectric, (g) is an auxiliary electrode,
αη is the second main electrode, (181 is an insulating substrate, (19 is a flat plate electrode, is a pipe, and is a needle electrode. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (4)

[Claims] (1) A first main electrode and a second main electrode having a plurality of openings arranged to face each other in the laser gas, a dielectric material arranged on the back surface of the first main electrode, and a first main electrode. An electrode system consisting of an electrode and an auxiliary electrode facing each other with the dielectric interposed therebetween, a first circuit that applies a pulse voltage between the first and second main electrodes, and a voltage between the auxiliary electrode and the first main electrode. In a pulsed laser oscillator equipped with a second circuit that applies
A pulsed laser oscillator characterized in that the second main electrode has a plurality of openings, and is equipped with an ultraviolet light generation source on the back surface of the second main electrode for pre-ionizing the laser gas between the first and second electrodes. (2) The ultraviolet light generation source includes a plurality of pin electrodes arranged at equal intervals on the back surface of the second main electrode, and a circuit for applying a voltage between the second main electrode and the pin electrode, and 2. The pulsed laser oscillator according to claim 1, wherein ultraviolet light is generated by arc discharge occurring between the second main electrode and the pin electrode. (3) The ultraviolet light generation source includes an insulating substrate installed on the back side of the second main electrode, a plurality of flat plate electrodes installed at equal intervals on the surface facing the second main electrode on this insulating substrate, and 2. The pulse laser oscillator according to claim 1, further comprising a circuit for applying a voltage between the flat electrodes, and generating ultraviolet light by creeping discharge occurring between the flat electrodes. (4) The source of the ultraviolet light is a pipe made of insulating material installed on the back of the second main electrode, a plurality of needle-like electrodes installed on this pipe at equal intervals, and a voltage is applied between the needle-like electrodes. 2. The pulse laser oscillator according to claim 1, further comprising a circuit, and generating ultraviolet light by discharge between the needle electrodes.