JPH02130884A - Pulse laser oscillator - Google Patents

Abstract

PURPOSE:To reduce switching energy and to largely increase the lifetime of a switch by supplying part of total electric energy to be supplied to a glow discharge from a DC-charged capacitor, and supplying the remaining energy from a pulse-charged capacitor. CONSTITUTION:When a switch 7 is closed, the voltage of a capacitor Ca5 is applied to a preliminary ionization electrode 3b to a shunt coil 12. Since a preliminary ionization electrode 3a is of ground potential, a high voltage is applied to a gap 4, and a spark discharge is generated in the gap 4. Currents are shunted to the plurality of the gaps 4 by the operation of a shunt coil 12, and all the gaps are spark discharged. A laser gas is preliminarily ionized between main electrodes 1 and 2 with an ultraviolet ray generated by the spark discharge. Charge stored in the capacitor Ca5 is fed in a circuit of the capacitor Ca5-the switch 7-the coil 12-the electrode 3b-the gap 4-the electrode 3a-the main electrode 1-the capacitor Cp13 to charge the capacitor Cp13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a pulsed laser oscillation device, and particularly to its discharge section and power supply configuration.

(Prior art) In discharge excitation type gas lasers, laser oscillation is obtained by generating a spatially uniform glow discharge in the laser gas, but pulsed lasers such as lateral excitation pulsed CO, lasers, and excimer lasers - In the oscillator, the laser gas pressure is above atmospheric pressure.

Furthermore, it is difficult to ignite the above glow discharge uniformly because it contains a gas component with strong electron adhesion.For this reason, preliminary ionization is performed prior to ignition of the glow discharge, and
It is common to apply a high-speed pulsed voltage to a discharge portion to form a glow discharge.

FIG. 5 is an example showing a discharge section structure and an excitation power supply circuit of a conventional pulsed laser oscillation device. (For example, the method shown in Laser Research, Vol. 13, No. 10, P814 (1980), etc.) A pair of main electrodes 1 and 2 are arranged facing each other, and a space surrounded by the main electrodes 1 and 2 is Filled with laser gas. Main electrode 2 is grounded.

A preliminary ionization electrode 3a is connected to the main electrode 1 and is electrically at the same potential. Pre-ionization electrode 3a and pre-ionization electrode 3
b are opposed to each other with a gap 4 in between, and are placed in the laser gas. The pre-ionization electrode 3b is insulated from the main electrode 1, drawn out from the laser gas, and connected to capacitors C and 5. One end of the charging inductance 6 is commonly connected to the pre-ionization type t4ii3b and the capacitor Ca5, and the other end is grounded.

The capacitors C and 5 are grounded via a switch 7 and connected via a charging resistor 8 to a high voltage power supply HV9. A capacitor CblO is connected between main electrodes 1 and 2. The above capacitors and inductances are 1
It is constructed by connecting one or more in parallel. Further, an optical resonator (not shown) is arranged in the direction perpendicular to the plane of the paper.

The operation of the conventional pulsed laser oscillation device configured as described above will be explained. In the initial state, switch 7 is open,
The capacitor Ca5 is charged through the path of high voltage power supply HV9 - charging resistor 8 - capacitor Ca5 - charging inductance 6 - ground. Since the capacitor CblO is not charged, the main electrode 1 is at ground potential. switch 7
When closed, the potential on the switch 7 side of the capacitor Ca5 becomes the ground potential, so that the potential on the pre-ionization electrode 3b side of the capacitor Ca5 is applied to the pre-ionization electrode 3b with the polarity opposite to the polarity charged in the capacitor Ca5. Since the pre-ionization electrode 38 is at ground potential, the gap 41? A high voltage is applied to Jll, and a spark discharge occurs in gap 4. The laser gas between the main electrodes 1.degree. 2 is pre-ionized by ultraviolet light generated by this spark discharge. The charge stored in the capacitor Ca5 flows through the path of switch 7 - capacitor Ca5 - pre-ionization electrode 3b - gap 4 - ionization electrode 3a - main electrode 1 - capacitor CblO, and flows to capacitor cbt.
o is being charged. When the voltage of the capacitor Cb10 increases and the voltage applied between the main electrodes 1 and 2 reaches the discharge breakdown voltage of the laser gas or higher, a glow discharge 11 is formed between the earth dragons wA1 and 2, and the laser gas is excited (not shown). Laser light is emitted in a direction perpendicular to the paper surface by the action of the optical resonator.

(Problem to be solved by the invention) In such a conventional pulsed laser oscillation device,
It is necessary to set the charging voltage of the capacitor Ca5 to several tens of kV or higher, and to increase the rate of charging the capacitor CblO to shorten the time interval between the occurrence of the pre-ionization discharge formed in the gap 4 and the time interval between the formation of the glow discharge 11. It is. For this reason, the maximum value and time rate of change of the current flowing through the switch 7 are extremely large, which not only limits the types of switches that can be used, but also shortens the life of the switch 7, which is determined by the characteristics of the switch 7. It was not possible to raise the charging voltage above the maximum allowable current value and allowable current change rate. In this way, the operating range and types of switches that can be used are limited, such as repeated operation or long-life operation. It has been difficult to realize the driving motion required for industrial applications.

Therefore, the present invention was proposed in order to eliminate the above-mentioned drawbacks, and its purpose is to provide a pulsed laser oscillation device that can significantly reduce the operational duty of the switch and expand the operating range of the laser. It is in.

[Structure of the invention]

(Means for Solving the Problems) The pulse laser oscillation device of the present invention includes a first capacitor and a second capacitor connected in series between main electrodes, a connection point of these capacitors being grounded, and a first capacitor connected in series between main electrodes. The second capacitor is pulse-charged by the action of a switch, and the second capacitor is charged with direct current.

(Function) According to the present invention configured as described above, a certain part of the total electrical energy supplied to the glow discharge is used to charge the second
Since the remaining energy can be supplied from the pulse-charged first capacitor, the switching energy controlled by the switch can be reduced.

(Embodiment) An embodiment of the present invention will be specifically described below with reference to FIGS. 1, 2, and 3.

Figure 1 shows the discharge section and excitation power supply circuit. A pair of main electrodes 1
, 2 are disposed facing each other in an airtight laser chamber filled with laser gas. The main electrode 1 has a pre-six
'ff The ionization electrode 3a is connected and has the same electrical potential. The pre-ionization electrode 3a and the pre-ionization electrode 3b face each other with a gap 4 in between and are placed in the laser gas.

The pre-ionization electrode 3b is insulated from the main electrode 1 and drawn out from the laser gas.

It is connected to the shunt coil 12. The shunt coil 12 is connected to a capacitor Ca5 via a switch 7, one end of the capacitor Ca5 is connected to a negative high voltage power supply HV9 via a charging resistor 8, and the other end is grounded. Main electrode 1
, 2, a capacitor C, 13 and a capacitor Cd14 are connected in series, and the connection point of both capacitors is grounded. The main electrode 2 is connected to the high voltage power supply HVA1 via a charging resistor 15.
6 and is also grounded via a high resistance 17. The voltage polarity of high voltage power supply HVA16 is high voltage power supply HV.
9 voltage polarity and opposite polarity.

In this embodiment, the polarity is positive, but if the polarity of the high voltage power supply HV9 is negative, the polarity of the high voltage power supply HVA16 is positive6.
One or more of the above capacitors, resistors, and inductances are connected in parallel. Also 1
An optical resonator (not shown) is arranged in a direction perpendicular to the plane of the paper.

The operation of the pulsed laser oscillation device configured as above will be explained.

In the initial state, switch 7 is open and high voltage power supply HV9
The capacitor Ca5 is charged through the path of - charging resistor 8 - capacitor Ca5 - ground. In addition, capacitor Cb1
4 is high voltage power supply HVA16-charging resistor 15-capacitor C
It is charged through the b14-ground path. capacitor C,
13 is not charged, the main electrode 1 is at ground potential. When switch 7 is closed, capacitor C,
5 voltage is applied to the preionization electrode 3b via the shunt coil 12. Since the pre-ionization electrode 3a is at ground potential, a high voltage is applied across the gap 4, and a spark discharge occurs in the gap 4. Current is shunted into the plurality of gaps 4 by the action of the shunt coil 12, and all the gaps 4 generate spark discharge. The laser gas between the main electrodes 1 and 2 is pre-ionized by the ultraviolet rays generated by this spark discharge. Further, at this time, the charge stored in the capacitor Ca5 is divided into the following: capacitor Ca5 - switch 7 - shunt coil 12 - pre-ionization electrode 3
The flow continues to charge the capacitor C, 13 through the path b - gap 4 - secondary ionization electrode 3a - main electrode 1 - capacitor C, 13. This situation is shown in FIG.

Assuming that the time when the switch 7 is closed is to, before this time, the voltage Vde of the capacitor Cd14 is the voltage Vd charged from the high voltage power supply HVA16, and the voltage Vpg of the capacitor Cp13 is 0. Time t. When the switch 7 is closed, the voltage of the capacitor CP13 rises to the negative side and reaches vP at one time t8. Capacitor C
, 13 and the voltage value of the capacitor Cd14 (=Vd+
V,) is applied between the main electrodes 1 and 2, and when this total voltage reaches the number of discharges i [pressure (=vb)] between the main electrodes 1 and 2, a glow discharge 11 is formed between the main electrodes 1 and 2. The laser gas is excited, and a laser beam is emitted in a direction perpendicular to the plane of the paper by the action of an optical resonator (not shown). The high resistance 17 has the function of stabilizing the potential of the main electrode 2.

Below, the features of the present invention will be described in more detail in comparison with the conventional example shown in FIG. To facilitate comparison with the conventional example, the capacitance value of capacitor C, 10 and the series capacitance value of capacitor C, 13 and capacitor Cd14 are equal, and the discharge breakdown voltage: vd between main electrodes 1 and 2 is equal to capacitor C, 6 to explain the case where the voltage of No. 13: vP and the voltage of capacitor Cd14: Vd are equal to the total value (= Vd + Vp)
The above relationships are as shown in the formula ■ and the formula ■.

Cp"Cp" Cd/ (Cp+Cd)
... ■Vb=V, +Vd
... ■Also, assuming that the electric energy stored in the capacitor C, 10 is equal to the sum of the electric energy stored in the capacitors CP13 and Cd14, the capacitor C, 13 and the capacitor Cd
14 and the voltage of capacitor Cp10, and the switching energy of capacitor Cd13: E,
and switching energy of capacitors c and io: Eb
The relationship is as follows.

This situation is shown in FIGS. 3(a) and 3(b), where the voltage is a value normalized by the voltage 2b of the capacitor CPIO.5 The switching energy is also normalized by the energy stored in the capacitors C and 10. From FIG. 3, when the capacitance values of capacitor C, 13 and capacitor Cd14 are equal, vd=vp, and the required voltage can be reduced to 50% of the conventional voltage. Furthermore, the switching energy EP is 50% of the switching energy Eb of the conventional system. When the capacitance value of the capacitor Cd14 is made larger than the capacitance value of the capacitor CP13, VP and EP are reduced to 50% or less compared to the conventional system, and the operational responsibility of the switch is significantly reduced. This operating condition is very effective in reducing the operating voltage of the switch when the laser gas pressure and the like are high and the firing voltage is high. Conversely, capacitor Cd
If the capacitance value of capacitor Cp14 is made larger than that of capacitor Cp13, the voltage and energy on the pulse charging side will increase, but even in that case, the switch energy will be smaller than in the conventional example, and the operational responsibility of the switch will be greatly improved. ing.

The operation is performed under the conditions where formulas ■, ■, and ■ hold true above, but if you want to increase the laser output under other operating conditions, you can easily increase the output by increasing the energy on the Cd side. This method has a greater degree of freedom in circuit configuration than conventional methods.

Next, another embodiment of the present invention will be explained in detail based on FIG.

The configuration of the main electrode 1.2 and the preliminary ionization electrodes 3a, 3b, whose discharge section and excitation power supply circuit are shown in FIG. 4, is the same as in the previous embodiment. The pre-ionization electrode 3b is insulated from the main electrode 1, drawn out from the laser gas, and connected to the capacitor Ca5. The main electrode 1 is grounded through a high resistance 17. One end of the charging inductance 6 is commonly connected to the preliminary ionization electrode 3b and the capacitor Ca5, and its terminal end is grounded.

Capacitor Ca5 is grounded via switch 7 and connected via charging resistor 8 to high voltage power supply HV9. Capacitors C and 13 and capacitor Cd14 are connected in series between the main electrodes 1 and 2, and the connection point of both capacitors is grounded. The main electrode 2 is connected to a high voltage power supply HVA 16 via a charging resistor 15 and is grounded via a high resistor 17. The voltage polarity of the high voltage power supply HVA16 is the same as the voltage polarity of the high voltage power supply HV9. In this embodiment, the polarity is positive, but it may be negative polarity.

One or more of the above capacitors, resistors, and inductances are connected in parallel. Also,
An optical resonator (not shown) is arranged in a direction perpendicular to the plane of the paper.

The operation of the pulsed laser oscillation device configured as above will be explained.

In the initial state, switch 7 is open and high voltage power supply HV9
The capacitor Ca5 is charged through the path of - charging resistor 8 - capacitor C, 5 - ground. In addition, capacitor Cd1
4 is high voltage power supply HVA16-charging resistor 15-capacitor C
d14-Charged through the ground path. Capacitor CP
13 is not charged, the main electrode 1 is at ground potential. When switch 7 is closed, capacitor Ca
Since the potential on the switch 7 side of the capacitor Ca5 becomes the ground potential, the potential on the pre-ionization electrode 3b side of the capacitor Ca5 becomes the ground potential.
, 5 with the polarity opposite to the voltage polarity charged to the ionization electrode 3
join b. Since the pre-ionization type fi3a is at ground potential, a high voltage is applied across the gap 4, and a spark discharge occurs in the gap 4. The laser gas between the main electrodes 1 and 2 is pre-ionized by the ultraviolet rays generated by this spark discharge.

The charge stored in the capacitor Ca5 flows through the path of the switch 7, the capacitor Ca5, the preliminary ionization electrode 3b, the gap 4, the secondary ionization electrode 3a, the main electrode 1, and the capacitor Cp13, and the capacitors C and 13 are charged. When the voltages of the capacitors C and 13 rise and the sum of the voltages of the capacitors CP13 and Cd14 reaches the discharge breakdown voltage between the main electrodes 1 and 2 or higher, a glow discharge 11 occurs between the main electrodes 1 and 2.
is formed, the laser gas is excited, and a laser beam is emitted in a direction perpendicular to the paper surface by the action of an optical resonator (not shown).

The voltage waveform in this case is similar to the previous embodiment shown in FIG. The high resistance 17 has the function of stabilizing the potentials of the main electrode 1 and the main electrode 2.

The above embodiments are examples of application to ultraviolet pre-ionization type pulsed lasers, but it goes without saying that the application is not limited to ultraviolet pre-ionization type pulsed lasers, but can also be applied to X-ray pre-ionization type pulse lasers, corona pre-ionization type pulsed lasers, etc. . Furthermore, the present invention is not limited to pulsed lasers, and can also be applied to devices that utilize discharge other than glow discharge, such as flash lamps.

〔Effect of the invention〕

According to the present invention configured as described above, a certain part of the total electrical energy supplied to the glow discharge can be supplied from the DC-charged capacitor, and the remaining energy can be supplied from the pulse-charged capacitor. The energy consumed by the switch can be significantly reduced, and the life of the switch can be significantly extended. In addition, since the capacitor capacity and pulse charging voltage on the pulse charging side can be freely combined, the peak value and rate of change of the switching current can also be freely selected, greatly expanding the range of usable switching elements, which was previously unavailable. It also becomes possible to use other switching elements. Furthermore, since the charging pulse waveform can be adjusted in accordance with the laser oscillation operation, it is easy to increase the output of laser oscillation.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing one embodiment of the pulsed laser oscillation device of the present invention, FIGS. 2 and 3 (a) and (b) are waveform diagrams explaining the circuit operation of the present invention, and FIG. FIG. 5 is a circuit diagram showing another embodiment of the present invention, and FIG. 5 is a circuit diagram showing a conventional pulse laser device. l...Lord l! Pole, 2... Main electrode, 3...
・Spark discharge pin, 4... Gap, 5... Capacitor C3, 6... Charging inductance 7... Switch, 8... Charging resistor, 9...
...High voltage power supply HV, 10...Capacitor c
b. 11... Glow discharge, 12... Shunt coil,
13... Capacitor c, 14... Capacitor Cd. 15...Charging resistor, 16...High voltage power supply HVA, 17
...High resistance. Agent Patent Attorney Yudo Ken Chika Ken Daishimaru Figure 2 Figure 1 Cd/CP Cd/Cρ (b Figure Figure

Claims (1)

[Claims] In a pulse laser oscillation device in which a capacitor is connected between a pair of opposing main electrodes, the capacitor is connected in series into two parts, one capacitor is charged with direct current, and the other capacitor is charged with pulses. Pulsed laser oscillation device.