JPH0318073A - Metal vapor laser device - Google Patents

Abstract

PURPOSE:To get high efficiency even in the case where the number of pulse repeat is high by providing a second pulse generating circuit separately from a first pulse generating circuit, and applying first pulse voltage from the first pulse generating circuit to a discharge tube, and then applying second pulse voltage from the second pulse generating circuit, being delayed by specified time. CONSTITUTION:This is equipped with a first pulse generating circuit 13a, which supplies first pulse voltage for generating gas discharge in a discharge tube 11, and a second pulse generating circuit 13b, which supplies second pulse voltage to the discharge tube 11 being delayed by a specified time from the first pulse voltage, and those are composed of charge/discharge capacitors 14a and 14b and switching means 15a and 15b being constituted by connecting many solid switching elements in series and parallel. And this is equipped with high voltage power sources 17a and 17b which supply power, through interference preventing reactors 20a and 20b, to the charge/ discharge capacitors 14a and 14b of the first and second pulse generating circuits 13a and 13b. Accordingly, the relaxation from a lower state to a ground state is accelerated between each pulse, and the inverted population with the next pulse becomes complete. Hereby, even if the number of pulse repeat is high, high efficiency can be obtained.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a metal vapor laser device equipped with a discharge tube that heats and vaporizes metal by gas discharge to obtain laser output. [Prior art] Fig. 4 shows, for example, a COPPER VAPORLAS cam off-age.
ERS COME OF AGE) Laser Focus July 1 9 8 2 (LASERFO
CUS, JULY, 1982) is a diagram showing a pulse generation circuit as a driving C source for a conventional copper vapor laser device, and in FIG. A charging diode, 4 a capacitor for charging and discharging, 5 a charging resistor, 6 a thyratron switch, and 7 a discharge tube (laser tube). Next, the operation will be explained. A high voltage (several KV to several tens of KV) generated from a high voltage power supply 1 is charged to a capacitor 4 via a reactor 2, a diode 3, and a charging resistor 5. In this charged state, when the thyratron switch 6 is turned on, the voltage stored in the main capacitor 4 passes through the thyratron switch 6 and is applied to the discharge tube 7, forming a gas discharge in the discharge tube 7. At this time, since the impedance of the discharge tube 7 becomes significantly smaller than the resistance value of the charging resistor 5, the current flowing through the thyratron switch 6 mainly flows through the discharge tube 7. Due to the thermal energy of this discharge, the temperature inside the discharge tube 7 increases to 1
The temperature is raised to about 500° C., and the metal, such as copper particles, stored in advance is turned into vapor, and the discharge tube is filled with copper vapor. The gas discharge formed in the discharge tube 7 accelerates electrons in the discharge plasma, and these electrons collide with the copper atoms filling the discharge tube 7 and raise the atomic level of the copper atoms to the first resonance level. Since the number excited to the lower level, which is a metastable level, is small, population inversion is formed. The copper atoms in the upper level fall to the lower level accompanied by laser oscillation, and then slowly relax from the lower level to the ground level. The above operation is repeated at several KHz. When the diameter of the discharge tube 7 is small, relaxation from the lower level to the ground level occurs through collision of the excited atoms with the wall of the discharge tube 7, and when the diameter of the discharge tube 7 is large, the relaxation occurs by the lower level atoms. This is done through superelastic collisions between low-speed electrons and low-velocity electrons, and its lifetime is as long as several hundred microseconds. [Problem to be solved by the invention] Since the conventional copper vapor laser device is configured as described above, the relaxation time from the lower level to the ground level is only a few hundred μSe.
If the next pulse is applied after waiting for the relaxation to complete, the number of pulse repetitions will become smaller, and if the number of pulse repetitions is increased, the number of lower levels during pulse application will increase, resulting in population inversion. There was a problem in that the copper vapor laser became incomplete and the efficiency of the copper vapor laser decreased. This invention was made to solve the above problems, and promotes relaxation from the lower level to the ground level between each pulse, making population inversion in the next pulse safer. By doing so, the object is to obtain a metal vapor laser device with high efficiency even when the number of pulse repetitions is high. [Means for Solving the Problems] A metal vapor laser device according to the present invention includes a switching means configured by connecting a charging/discharging capacitor and a large number of solid state switching elements in series and parallel, and generates a gas discharge in the discharge tube. a first pulse generating circuit that supplies a first pulse voltage; a second pulse generating circuit that supplies a second pulse voltage to the discharge tube after a predetermined time delay from the first pulse voltage; It is equipped with a plurality of independently provided high-voltage power supplies that respectively supply power to the charging and discharging capacitors of the second pulse generating circuit via interference prevention reactors.

[For use] In this invention, a second pulse voltage generated from a second pulse generation circuit is applied between the first pulse voltage supplied from the first pulse generation circuit, and lower level atoms are This causes strong superelastic collisions with low-velocity electrons, and as a result, relaxation of lower-level atoms is promoted, and population inversion occurs when the first pulse voltage is applied from the first pulse generation circuit. It becomes more complete and prevents the laser efficiency from decreasing even at high repetition rates. In addition, since the first pulse generating circuit and the second pulse generating circuit are constructed using a switching means constructed by connecting a large number of solid-state switching elements in series and parallel, the response speed is fast.
The switching time does not change depending on usage conditions, such as the anode delay time that existed in conventional Cylytron switches, resulting in high reliability and long life. [Example J Hereinafter, an example of the present invention will be explained with reference to the drawings. 1st
In the figure, 1l is a discharge tube, 12 is a charging resistor connected in parallel with the discharge tube 11, and 13a is a charging/discharging capacitor 14a and a switch means 15a, which is constructed by connecting a number of solid-state switching elements in series and parallel, connected in series. The first pulse generating circuit 13b is a second pulse generating circuit constructed by connecting in series a charging/discharging capacitor L4b and a switching means 15b constructed by connecting a large number of solid state switching elements in series and parallel. These first and second pulse generation circuits 13a,
13b are connected in parallel to the discharge tube 11 via reactors 16a and 16b, respectively. 17a is a high-voltage power supply that supplies power to the charge/discharge capacitor 14a via the reactor 18a, diode 19a, and interference prevention reactor 20a; 17b is a high-voltage power supply that supplies power to the charge/discharge capacitor 14b via the reactor 18b, diode 19b, and interference prevention reactor 20b; 2l is an oscillator that outputs a conductive signal to the switch means 15a, and 22 is a delay circuit that delays the conductive signal by a predetermined time and supplies it to the switch means 15b. FIG. 2 is a block diagram showing a specific example of the switch means 15a, 15b, in which, for example, a large number of FETs 23 are connected in series and parallel. In addition, instead of FET23, SIT, I
It may also be a solid state switching element such as a GBT, SI thyristor, transistor, or thyrisk. Next, the operation will be explained with reference to the time chart shown in FIG. From the high voltage power supply 17a, (17b), the reactor 18
a (18b), diode 19a (19b). A high voltage is charged to the charge/discharge capacitor 14a (14b) via the interference prevention reactor 20a (20b). Next, when the switching means 15a is turned on by the conduction signal from the oscillator 2l, the high voltage charged in the charging/discharging capacitor 14a is applied to the discharge tube 1l, and a gas discharge is formed in the discharge tube 11. On the other hand, the delay circuit 22 delays the conduction signal from the oscillator 2l by a predetermined time, and then makes the switch means 15b conductive.
The high voltage charged in the charging/discharging capacitor 14b is applied to the discharge tube 11. As a result, the charging voltage of the charging/discharging capacitor 14a is applied to the discharge tube 1l at time 70 to generate gas discharge, and the charging voltage of the charging/discharging capacitor 14b is applied after a delay of a predetermined time from time t0. be done. The currents Ia and Ib flowing through the switch means 15a and 15bL:v due to the conduction are determined by the impedances of the charging and discharging capacitors 14a and 14b, the reactors 16a and 16b, and the discharge tube 11, and have a waveform as shown in FIG. becomes. In the copper vapor laser device, lower level atoms are relaxed to the ground level by superelastic collisions between the lower level and slow electrons when the diameter of the inner tube 2 is large. That is, C u * + e ilawl- C u + e
(ras) Here, Cu* is a lower level atom Cu is a ground level atom e jml. 1 is a slow electron ear and Hatatomi tl is a fast electron. The voltage applied from the second pulse generation circuit 13b is Although the voltage is low and does not excite the atoms to the upper level, the electrons are accelerated and collisions between the electrons and the copper atoms become more intense.As a result, superelastic collisions between the lower level atoms and electrons become active. Therefore, the relaxation of the lower level is promoted. Note that the inductance value of the interference prevention reactors 20a and 20b is selected so as to have a large impedance with respect to the frequency component of the current flowing when the switching means 15a and 15b are turned on. For example, in general, in the case of a copper vapor laser device, the current flowing through the discharge tube l1 has a maximum pulse width of 500μ88C, so the fundamental frequency is approximately IMHz.The interference prevention reactors 20a and 20b are sufficiently In order to have a large impedance, if the inductance of the interference prevention reactors 20a and 20b is Lz, then 2ifLz》Zr Zr needs the impedance of the discharge tube 1l. Usually, the impedance ZT is from several ohms to several tens of ohms. , for example, 50Ω, then the inductance Lz should be selected to be greater than HiooμH.By selecting the inductance Lz as described above, for example, when the switch means 15a and 15b are turned on, the charging and discharging capacitors 14a and 14b are discharged. No current starts to flow. [Effects of the Invention] As described above, according to the present invention, the second pulse generation circuit is provided separately from the first pulse generation circuit, and the first pulse generation circuit is connected to the discharge tube. After the lth pulse voltage is applied from
Since the second pulse voltage is applied to the discharge tube again from the second pulse generation circuit after a predetermined time delay, the time for the lower level atoms to relax to the ground level is shortened.
As a result, the population inversion becomes more complete when the next pulse is applied from the l-th pulse generation circuit, which has the effect of making it possible to obtain a highly efficient metal vapor laser device even at high repetition rates. In addition, since the switching means of the first pulse generation circuit and the -second pulse generation circuit are constructed by connecting a large number of solid state switching elements in series and parallel, the response speed is fast, and the switching means of the first pulse generation circuit and the -second pulse generation circuit are constructed by connecting a large number of solid state switching elements in series and parallel. Switching time does not change depending on usage conditions such as anode delay time, resulting in high reliability and long life.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a metal vapor laser device according to an embodiment of the present invention, Fig. 2 is a configuration diagram of a switch means, Fig. 3 is a time chart diagram explaining the operation of the above embodiment, and Fig. 4 is a conventional one. FIG. 2 is a circuit diagram of the gold R vapor laser device of FIG. 1l is a discharge tube, 13a is a first pulse generating circuit, 13
b is a second pulse generation circuit; 15a and 15b are switch means; 1.7a and 17b are high-voltage power supplies; 21 is an oscillator;
2 is a delay circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A discharge tube that heats and vaporizes metal by gas discharge to obtain a laser output, and a switch means configured by connecting a large number of solid state switching elements in series and parallel are connected to a charge/discharge capacitor, and by opening and closing the switch means, the discharge a first supplying a first pulsed voltage that produces a gas discharge in the tube;
a second pulse generating circuit which connects a switch means having the same configuration as the switch means to a charging/discharging capacitor and supplies a second pulse voltage to the discharge tube by opening and closing the switch means; an oscillator that supplies a conduction signal to the switch means of the first pulse generation circuit; a delay circuit that delays the conduction signal by a predetermined time and supplies the conduction signal to the switch means of the second pulse generation circuit; A metal vapor laser device comprising a first power source and a second power source that are independently provided to supply power to each of the charging and discharging capacitors of the pulse generating circuit and the second pulse generating circuit via an interference prevention reactor. .