JPH04779A - Gas laser generator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a stable and reliable gas laser oscillation device.

(Prior art) Figure 2 (a) shows a conventional axial flow gas laser oscillator in which laser gas is flowed in the optical axis direction of a discharge tube made of an insulator, and a high temperature is created between electrodes provided at both ends of the discharge tube. 1 is a diagram showing the configuration of a gas laser oscillation device that generates a laser beam by applying a voltage. 1 is a discharge tube made of a dielectric material such as glass, 2 and 3 are electrodes arranged inside the discharge tube 1, and 4 is a high voltage power supply section connected to these electrodes 2 and 3. A high voltage is applied between the picture electrodes 2 and 3. 5 is a laser discharge space between the electrodes 2 and 3, 6 is a total reflection mirror of the laser, and 7 is a partial reflection mirror, which are arranged opposite to each other with the laser discharge space 5 interposed therebetween to form an optical resonator. ing.

Further, numeral 8 represents a laser beam output from the above-mentioned partial reflecting mirror 7, and arrow 9 represents the direction of flow of laser gas, which is circulating in the laser device formed in an axial flow type. 10 is an air pipe; 11° and 12 are heat exchangers for reducing the discharge in the laser discharge space 5 and the temperature of the laser gas raised by the blower; and 13 is a blower. In the discharge space 5, air is blown so that a gas flow of about 100 m/sec is obtained.

The conventional trickle type gas laser oscillation device is constructed as described above, and first, a high voltage is applied to the electrodes 2 and 3 from the high voltage power supply section 4 to generate a glow discharge in the laser discharge space 5.

The laser gas passing through the laser discharge space 5 is excited to oscillate by the discharge energy of the glow discharge, and the excited laser gas enters a resonant state by an optical resonator constituted by a total reflection mirror 6 and a partial reflection mirror 7. The partially reflecting mirror 7 then outputs the laser beam 8, which is used for laser beam processing and the like.

FIG. 2(b) shows the configuration of the above-mentioned high voltage power supply unit 4. Normally, a three-phase 200V commercial AC power supply is applied to its input, and the DC voltage obtained by rectifying the AC input by the DC smoothing circuit 14 is output. , is applied to the high-frequency switching element 16 controlled by the switching control circuit 15, and the DC voltage input to the primary winding of the high-voltage high-frequency transformer 17 is thereby intermittent, thereby boosting the high-frequency voltage to the secondary winding. A voltage is induced, and the high voltage rectifying and smoothing circuit 18 outputs it as a DC high voltage of about 30 kV.

FIG. 2(c) is a partial diagram of the high voltage power supply section 4 to explain the above-mentioned high frequency switching element 16. The high frequency switching element 16 is composed of a MOS-FET 19 as an H bridge, and is switched at an operating frequency f. . Therefore, an even current flows through the primary side of the high voltage high frequency transformer 17, and a corresponding stable high voltage is output to the secondary side.

(Problems to be Solved by the Invention) In the high voltage power supply unit 4 of the conventional gas laser oscillation device as described above, when the discharge becomes an arc state, the secondary side of the high voltage high frequency transformer 17 becomes close to a short circuit state. However, there is a problem in that an excessive current flows through each MO3-FET 19 and destroys it.

In view of the above-mentioned conventional problems, the present invention uses a high-voltage, high-frequency transformer 17 having an appropriate impedance to transform the MOS-FET 1 of the high-frequency switching element of the high-voltage power supply section.
An object of the present invention is to provide a gas laser oscillation device that suppresses the current flowing through the laser beam 9 and prevents current breakdown.

(Means for Solving the Problems) The present invention achieves the above object by flowing laser gas into a discharge tube provided with electrodes at both ends, and applying a high voltage to the electrodes from a high voltage power source to cause glow discharge. In an axial gas laser oscillator that generates a laser beam in the axial direction of a discharge tube, the high voltage power supply section includes a DC smoothing circuit that converts a commercial AC power supply into DC, and a high frequency switching element that intermittents the output thereof. It is composed of a high voltage, high frequency transformer, and a high voltage rectifying and smoothing circuit, and the high frequency switching element has an H-bridge configuration of MOS-FET, and when the secondary winding of the high voltage, high frequency transformer is short-circuited, the primary winding side is The switching frequency of the high-frequency switching element is f, the maximum rated current between the drain and source of each MOS/FET is ■, and the DC output voltage of the DC smoothing circuit is E. This is achieved by selecting the above inductance L to a value that satisfies L≧E/27cfI.

(Function) The high voltage power supply section 4 of the present invention can clearly prevent the destruction of the MOS/FET 19 constituting the high frequency switching element due to the inductance L even during arc discharge, so the laser beam can be stabilized. The result is a highly reliable gas laser oscillation device that outputs light.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view (a) showing a high-voltage high-frequency transformer, which is the main part of an embodiment of the present invention, and a characteristic diagram (b) showing the breakdown rate of a MOS/FET. Since it is the same as FIG. 2(a), illustration is omitted.

First, in FIG. 1(a), 20 is a primary winding of the high voltage high frequency transformer 17, 21 is a secondary winding, and 22 is a ferrite core. In the winding of such a high voltage high frequency transformer I7, in the case of the present invention, the number of turns of the primary winding 20 is increased compared to the conventional example.

FIG. 1(b) is a characteristic diagram showing the breakdown rate of the MOS-FET 19 constituting the high frequency switching element 16 with respect to the number of turns of the primary winding 20 of the high voltage high frequency transformer 17, where the number of turns of the primary winding (horizontal axis) Point P is the inductance seen from the primary side when the secondary winding of the high-voltage high-frequency transformer 17 is short-circuited, the switching frequency of the high-frequency switching element 16 is f, and the maximum rating between the drain and source of each MO5-FET 19 is When the current is 2 and the DC output voltage of the DC smoothing circuit 14 is E, the value of the inductance L that satisfies L=E/2πFI is shown.

As is clear from this, the inductance L of the primary winding
It can be seen that if the number of windings is selected so that L≧E/2πf1 is satisfied, the MOS-FET 19 can be prevented from voltage breakdown.

That is, in the present invention, the high frequency switching element 16 is
The voltage breakdown of the MOS-FET 19 is prevented by configuring it as an H-bridge of the S-FET 19, and setting the number of turns of the primary winding of the high-voltage high-frequency transformer I7 driven by it to have an inductance L that satisfies L≧E/2πfI. It is possible to stably output a reliable laser beam.

(Effects of the Invention) As is clear from the above description, the present invention converts the high voltage power supply section of the gas laser oscillation circuit into a DC smoothing circuit.

It is configured by providing a high frequency switching element, a high voltage high frequency transformer, and a high voltage rectifying and smoothing circuit, and in particular, the high frequency switching element is configured as an H bridge of MOS-FET, and the switching output is applied to the primary of the high voltage high frequency transformer. This is a gas laser oscillation device that outputs a stable and reliable laser beam by selecting the optimum number of winding turns, and its use can be of great benefit.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view (a) showing the windings of a high-voltage, high-frequency transformer, which is the main part of an embodiment of the present invention, and a characteristic diagram (b) showing the breakdown rate of MOS/FET, and Figure 2 is a conventional gas laser. Block diagram of oscillator (a), block diagram of high voltage power supply section (b)
, and a partial circuit diagram (c) of the high voltage power supply section. DESCRIPTION OF SYMBOLS 1... Discharge tube, 2, 3... Electrode, 4... High voltage power supply section, 5... Laser discharge space, 6... Total reflection mirror, 7... Partial reflection mirror, 8.・Laser beam,
10...Air pipe, 11゜12...Heat exchanger, 13.
...Blower, 14.. DC smoothing circuit, 15.. Switching control circuit, 16.. High frequency switching element. 17... High voltage high frequency transformer, 18... High voltage rectifier smoothing circuit, 19... MOS-FET, 20...
...Primary winding, 21...Secondary winding, 22...Ferrite core. Patent applicant Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] (1) Axial flow in which laser gas is flowed into a discharge tube with electrodes installed at both ends, and a high voltage is applied to the electrodes from a high voltage power supply to cause a glow discharge and generate a laser beam in the axial direction of the discharge tube. In the type gas laser oscillation device, the high voltage power supply section is composed of a DC smoothing circuit that converts a commercial AC power source into DC, a high frequency switching element that cuts and cuts the output, a high voltage high frequency transformer, and a high voltage rectifying and smoothing circuit. The above high frequency switching element is a MOS/FET.
The inductance seen from the primary winding side when the secondary winding of the high voltage high frequency transformer is short-circuited is L.
, the switching frequency of the high-frequency switching element is f, the maximum rated current between the drain and source of each MOS/FET is I, and the DC output voltage of the DC smoothing circuit is E, then the inductance L of the high-voltage high-frequency transformer is , L≧E/2πfI. (2) The gas laser oscillation device according to claim (1), characterized in that a high voltage, high frequency transformer is used in which the inductance L is set to a value satisfying L≧E/2πfI by increasing or decreasing the number of turns of the primary winding.