JPH0276282A - Pulse laser oscillator - Google Patents

Abstract

PURPOSE:To achieve a large output laser light by placing a plurality of spark discharge pins for preliminary ionization on the rear surface of a main electrode which is a cathode in a pair of main electrodes and a plurality of spark discharge pins for preliminary ionization together and by connecting a control device for discharging each spark discharge pin in a specified amount of time, CONSTITUTION:A plurality of spark discharge pins 3 for preliminary ionization are provided at the rear surface side of a main electrode 2 in mesh-shape which is placed opposing a main electrode 1 and a plurality of spark discharge pins 10 for auxiliary ionization are provided along with these spark discharge pins 3 for preliminary ionization. Switches S1-S3 are connected to a control device 11 which controls each switch operation at a specified time. Then, after glow discharge occurs, the spark discharge pin 3 for auxiliary ionization is discharged, thus ionizing laser gas near a cathode and supplying electrons which result in shortage due to grow discharge. It achieves a large output laser light.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a pulsed laser oscillation device with an improved discharge section structure.

(Prior art) In order to obtain good laser oscillation in a gas-mediated laser, it is necessary to generate a spatially uniform discharge in the laser medium, but it is necessary to generate a spatially uniform discharge in the laser medium. In a pulsed laser oscillation device that generates short-pulse laser light, the operating gas pressure is as high as several atmospheres, and it also contains CO2 gas, which has strong electron adhesion, so the above-mentioned discharge converges and becomes an arc discharge. Prone.

To prevent this, a common method is to perform preliminary ionization prior to main discharge.

Figure 3 shows J, Phys, E Sci, Instru
This figure shows an example of a discharge section structure and an excitation power supply circuit of a conventional pulsed laser oscillation device, as disclosed in J. M., 19.1034 (1986). That is, the discharge part a is arranged in a laser medium, and a mesh-shaped second main electrode 2 is arranged opposite to the first main electrode 1. A plurality of spark discharge pins 3 for pre-ionization are arranged vertically in the .

Moreover, between the two main electrodes 1 and 2, there is Cz.

A pulse shaping circuit consisting of L+ is connected.

Note that Ld is the residual inductance of the circuit.

Further, a charging capacitor Cm is connected to the pulse shaping circuit.

On the other hand, a shunting inductance Lb is connected to each of the spark discharge pins 3 for preliminary ionization, and is connected to a capacitor Cpt. Further, this spark discharge pin 3 for pre-ionization is arranged opposite to the second main electrode 2 with a gap of several mm.

Roughly speaking, a charging capacitor Cm connected to the pulse shaping circuit is connected to a high voltage power supply (not shown) via a resistor R1, and the other end is grounded via an inductance 1-m. Similarly, the capacitor CDt is connected to a high voltage power supply (not shown) via a resistor R2, and the other end is grounded via an inductance Lpt. Further, in the longitudinal direction of the main electrodes 1 and 2 (in the vertical direction of the paper)
Optical resonators (not shown) are provided at both ends.

The operation of the conventional pulsed laser oscillation device configured in this manner will be described below. That is, the capacitor Cm is charged through the path of high voltage power supply, resistor R1, capacitor Cm, and inductance lm. On the other hand, the capacitor C1)t is charged through a path of high voltage power supply, resistor R2, capacitor C1ot, and inductance Lpt.

First, when switch S2 is closed, capacitor C
pt voltage is applied to spark discharge pins 3 and 2 for pre-ionization.
spark discharge is generated between the two main electrodes. The ultraviolet rays generated by this spark discharge cause
The laser gas between the opposing main electrodes 1°2 is pre-ionized.

Next, when the switch S1 is closed after a certain period of time has passed after the switch S2 is closed, the pulse shaping circuit is pulse-charged with the voltage charged in the capacitor Cm, and a pulse is generated between the main electrodes 1 and 2. A voltage is applied. When the voltage between the main electrodes 1 and 2 reaches a certain value or more, the main electrodes 1 and 2
, a glow discharge is ignited between . The laser gas is excited by this glow discharge, and a laser beam is generated in a direction perpendicular to the paper surface by the action of an optical resonator (not shown).

(Problem to be Solved by the Invention) However, in the conventional pulsed laser generator having the above-mentioned configuration, when the discharge current is connected for a long time, even though the discharge current is flowing, the laser is emitted. There were issues that needed to be resolved, such as a decrease in output.

This point will be explained based on FIG. 2, which shows the relationship between the change in laser output over time and the operating time of the switch. That is, in the conventional pulsed laser oscillation device, as shown by the broken line A, the laser output decreases from the middle of the discharge current, and even if the characteristic time of the pulse shaping circuit is lengthened, the laser output time does not increase. .

This is because a streamer-shaped contracted discharge occurs near the cathode, making the discharge unstable and reducing the laser output.

In this way, in the conventional pulsed laser oscillation device, even if the discharge current pulse width on the excitation power supply circuit side is increased,
Since the discharge became unstable, the laser output decreased, and it was not possible to make the laser output a longer pulse or increase the output.

The present invention was proposed to solve the above-mentioned drawbacks, and its purpose is to
It is an object of the present invention to provide a pulse laser generator that can ignite a discharge in a stable state, lengthen the laser output pulse, and obtain a large output laser beam.

[Structure of the Invention] (Means for Solving the Problems) The present invention has a pair of main electrodes disposed in a laser gas and with the laser optical axis as the longitudinal direction, and a wire for supplying energy between the main electrodes. In a pulsed laser oscillation device that connects a capacitor and pre-ionizes a main discharge space between main electrodes, a plurality of spark discharge pins for pre-ionization are provided on the back side of the main electrode which is a cathode among the pair of main electrodes; A control WJ that can arrange multiple spark discharge pins for auxiliary ionization in parallel and discharge each spark discharge pin at a predetermined time.
The device is connected.

(Function) According to the pulsed laser oscillation device of the present invention, first, the spark discharge pin for pre-ionization discharges to pre-ionize the space between the main electrodes, and then glow discharge occurs between the main electrodes. Then, after a certain period of time, the spark discharge pin for auxiliary ionization discharges, ionizing the laser gas near the cathode, and by appropriately supplying electrons that are insufficient due to glow discharge, the glow discharge can be continued in a uniform state. .

(Example) Hereinafter, an example of the present invention will be described in detail based on FIGS. 1 and 2. Incidentally, the same members as those of the conventional type shown in FIG. 3 are given the same reference numerals, and the description thereof will be omitted.

In this embodiment, as shown in FIG. 1, a mesh-shaped second main electrode 2 is disposed opposite to the first main electrode 1.
A plurality of spark discharge pins 3 for pre-ionization are arranged on the back side of the paper in a direction perpendicular to the plane of the paper, and a plurality of spark discharge pins 3 for auxiliary ionization are arranged in parallel with the spark discharge pins 3 for pre-ionization. A spark discharge pin 10 is provided.

In addition, a shunting inductance lb is connected to the spark discharge pin 3 for pre-ionization and the spark discharge pin 10 for auxiliary ionization, which constitute the two rows of spark discharge pins, and are connected to capacitors Cpt and C1)2, respectively. It is connected. These capacitors Cpt and Cpz are resistors R2
The other end is connected to a high voltage power supply (not shown) via inductances Lp1 and Lp2, and is grounded via inductances Lp1 and Lp2.

Roughly, switch S1. S2.83 are connected between one end of the high voltage side of each capacitor Cm, Cpt, CI)2 and the ground potential.

Further, the switches St, 32, and S3 are connected to a control device 11, and are configured such that the control device 11 can control the operation of each switch at a predetermined time.

The pulsed laser oscillation device of this embodiment having such a configuration operates as described below. That is, capacitor Cm
is charged through a path of high voltage power supply, resistor R1, capacitor Cm, and inductance 1 m, and its charging polarity is negative, and the second main electrode 2 is connected to have a negative potential. Further, the capacitor CI)t is charged by the path of high voltage power supply - resistor R2 - capacitor Cpt - inductance pl, and furthermore, the capacitor Cp2 is charged by the path of high voltage power supply - resistor R2 - capacitor Cp2 - inductance Lpz
It is being charged through the following route.

In this state, when the switch S2 is first closed, the voltage of the capacitor Cp1 is applied between the pre-ionization spark discharge pin 3 and the second main electrode 2, and a spark discharge occurs between them. The ultraviolet rays generated by this spark discharge preliminarily ionize the laser gas between the opposing main electrodes 1 and 2.

Next, the switch S1 is closed after a certain period of time after the switch S2 is closed, and the voltage charged in the capacitor Cm is
The pulse shaping circuit is pulse charged and a pulse voltage is applied between the main electrodes 1 and 2.

Then, when the voltage between the main electrodes 1 and 2 reaches a certain value or more, a glow discharge is ignited between one electric current In1.2. This glow discharge excites the laser gas, and the vanguard carrier (
(not shown), laser light is generated in a direction perpendicular to the plane of the paper.

Further, after a certain period of time has elapsed, the switch S3 is closed, and the voltage of the capacitor Cp2 is applied between the spark discharge pin 10 for auxiliary ionization and the second main electrode 2, and spark discharge occurs between them. This spark discharge ionizes the laser gas mainly in the vicinity of the second main electrode 2.

FIG. 2 shows the temporal change in laser output in the pulsed laser oscillation device of this embodiment configured as described above. That is, in FIG. 2, in the discharge section of the conventional pulsed laser oscillation device, the discharge contracts mainly due to a lack of electrons near the cathode, and the laser output attenuates as shown by the broken line A.
In this embodiment, the lack of electrons near the electrodes can be compensated for by causing spark discharge using the spark discharge pin 10 for auxiliary ionization and ionizing the laser gas again, so that the lack of electrons near the electrodes does not occur. First, the glow discharge continues in a uniform state. As a result, the laser output can also be sustained for a long time, as shown in FIG. 2B.

In this way, according to this embodiment, after the laser gas between the opposing main electrodes 1 and 2 is pre-ionized by the spark discharge pin 3 for pre-ionization, the voltage of the pulse shaping circuit is applied to the discharge part a. The glow discharge is ignited and the laser medium is excited, but at that moment the spark discharge pin 10 for auxiliary ionization is ignited again and the laser gas between the main electrodes is ionized, so that the current of the glow discharge cannot be sustained. Even when the time is long, the discharge does not contract, the laser output can be made into a long pulse, and a high output laser beam can be obtained.

[Effects of the Invention] As described above, according to the present invention, among the pair of main electrodes,
A control system that allows multiple spark discharge pins for preliminary ionization and multiple spark discharge pins for auxiliary ionization to be placed side by side on the back of the main electrode, which serves as a cathode, and allows each spark discharge pin to discharge at a predetermined time. By simply connecting the device, even when a long pulse current is applied, the discharge can be ignited in a stable state, and the laser output can be made into a long pulse, making it possible to obtain a high output laser beam. Laser emitting device can be provided.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the pulsed laser excavation device of the present invention, Fig. 2 is a diagram showing the discharge characteristics of the present invention and the conventional pulsed laser excavation device, and Fig. 3 is the conventional pulsed laser excavation device. This is a circuit diagram showing an example. DESCRIPTION OF SYMBOLS 1... First main electrode, 2... Mesh-shaped second main electrode, 3... Spark discharge pin for preliminary ionization, 10.
... Spark discharge pin for auxiliary ionization, 11... Control device.

Claims (1)

[Scope of Claims] A pair of main electrodes are disposed in the laser gas and have the laser optical axis in the longitudinal direction, an energy supply capacitor is connected between the main electrodes, and a main discharge space between the main electrodes is provided. In a pulsed laser oscillation device for pre-ionizing, a plurality of spark discharge pins for pre-ionization and a plurality of spark discharge pins for auxiliary ionization are arranged side by side on the back side of the main electrode which serves as a cathode among the pair of main electrodes. 1. A pulsed laser oscillation device characterized in that a control device is connected to the spark discharge pins to cause each spark discharge pin to discharge at a predetermined time.