JPH05160484A - Pulse generator for pulse laser - Google Patents

Abstract

PURPOSE:To obtain a pulse generator for pulse laser to protect from the over- voltage noise applied from a switch circuit, a gate circuit which can conduct the switch circuit to discharge a capacitor so that discharge current may be supplied to a laser discharge tube. CONSTITUTION:A parallel circuit composed of a resistor 21 and a diode is connected with the output side of a gate circuit 12, and a cathod of the diode is set to be a switch circuit side. Thus, the resistor prevents the over-voltage noise, and further the diode adds to the switch circuit a conduction signal outputted from the gate circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse generator for a pulse laser for generating a short wavelength pulse laser by repeating pulse discharge of a copper vapor laser, an excimer laser or the like.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing a pulse generator for a pulse laser using a conventional copper vapor laser. In the figure, 1 is a high voltage power source, 2 is a charging reactor connected to a high voltage power source 1, 3 is a charging diode serially connected to the charging reactor 2, 4 is a charging / discharging capacitor serially connected to the charging diode 3, and 8 is a high-speed switching element 9 composed of a large number of FETs (field effect transistors) or the like. A switch circuit composed of a series-parallel circuit, which is connected between the charging diode 3 and the high-voltage power supply 1.

A reverse current suppressing element 10 is connected in series with the capacitor 4 and is composed of a series-parallel circuit of a plurality of diodes. Reference numeral 11 is a bypass resistor connected in parallel to the reverse current suppressing element 10, 7 is a laser discharge tube connected in parallel to the switch circuit 8 via the reverse current suppressing element 10 and the capacitor 4, and 5 is connected in parallel to the laser discharge tube 7. It is a charging resistor.

Reference numeral 12 is a gate circuit for driving the switch circuit 8, and a common gate terminal G of each parallel circuit stage of the high-speed switch elements 9 such as FETs forming the switch circuit 8.
And a common source terminal S, and a gate terminal G
Is configured to apply a conduction signal to.

Reference numeral 13 denotes an optical oscillator for generating an optical pulse, and 14
Is an optical pulse generated by the optical oscillator 13 for each gate circuit 12
It is an optical fiber for giving to the photoelectric conversion element inside.

FIG. 3 shows the structure of the gate circuit 12, 17 is a photoelectric conversion element for converting the optical pulse transmitted through the optical fiber 14 into an electrical pulse signal, and 15
Is a bias resistor connected to the output side of the photoelectric conversion element 1,
Reference numeral 16 denotes a waveform shaping circuit that shapes the pulse signal output from the photoelectric conversion element 17 into a conduction signal and applies the waveform to the gate terminal G.

Next, the operation will be described. In FIG. 2, from the high voltage power supply 1, through the charging reactor 2, the charging diode 3, the bypass resistor 11 and the charging resistor 5,
The capacitor 4 is slowly charged with a high voltage. Next, when the switch circuit 8 is turned on by the turn-on signal from the gate circuit 12, the high voltage of the capacitor 4 is applied to the reverse current suppressing element 10.
A pulse voltage for several hundreds of nanoseconds is applied to the laser discharge tube 7 via. As a result, the laser discharge tube 7 is discharged, and its discharge current i _X flows through the path of the capacitor 4, the switch circuit 8, the laser discharge tube 7, the reverse current suppressing element 10 and the capacitor 4. At this time, the reverse current suppressing element 10 suppresses the reverse current of the oscillating current due to the interference of the circuit.

In FIG. 3, an optical pulse having a narrow pulse width sent from the optical oscillator 13 through the optical fiber 14 is converted into an electric pulse signal by the photoelectric conversion element 17.
This pulse signal is subjected to waveform shaping by the waveform shaping circuit 16 so that it is added to the common gate terminal G of each FET parallel circuit stage as a conduction signal composed of a pulse signal having a narrow pulse width, and each FET is rendered conductive, thereby making the switch circuit. 8. Make all 8 conductive.

[0009]

Since the conventional pulse generator for pulsed lasers is constructed as described above, one of the series stages of the plurality of high-speed switching elements 9 forming the switching circuit 8 becomes conductive. If a timing deviation occurs, an excessive voltage is applied to both ends of the high-speed switching element 9, and overvoltage noise jumps into the gate circuit 12 through the drain-gate capacitance of the high-speed switching element 9 and destroys the components in the gate circuit 12. There was a problem that it did.

[0010] For example, the timing of the switching of a particular stage delayed, as shown in FIG. 4, the second series stage t ₀
If all are turned on at the same time, an overvoltage is applied until the stage turns on at t ₁ . As shown in FIG. 5, the equivalent circuit when the high-speed switching element 9 is OFF is
Since it is represented by capacitors 18, 19 and 20, the overvoltage of FIG.
Through the gate circuit 12. Due to this inflowing overvoltage, there is a problem that the waveform shaping circuit 16 is destroyed, for example.

The present invention has been made in order to solve the above problems, and a pulse for a pulse laser capable of removing the overvoltage noise jumping into the gate circuit and greatly improving the reliability of the gate circuit. The purpose is to obtain a generator.

[0012]

A pulse generator for a pulse laser according to the present invention has a resistor connected between an output side of a gate circuit and a switch circuit, and a diode and a cathode connected to the resistor in parallel with the resistor. It is connected toward the switch circuit side.

[0013]

The resistor according to the present invention blocks overvoltage noise from the switch circuit, and the diode allows the conduction signal output from the gate circuit to pass and supplies the signal to the switch circuit.

[0014]

EXAMPLES Example 1. FIG. 1 shows an embodiment of the gate circuit 12, and the portions corresponding to those in FIG. In FIG. 1, 21 is a waveform shaping circuit 1.
6, a resistor connected between the output side of the gate circuit 12, that is, the output side of the gate circuit 12 and the gate terminal G that is the input side of the switch circuit 8, and 22 is a diode connected in parallel with the resistor 21. The anode is connected to the waveform shaping circuit 16, and the cathode is connected to the gate terminal G.

Next, the operation will be described. When overvoltage noise is applied to the gate circuit 12 from the gate / source terminals G and S of the switch circuit 8, the resistor 21 blocks the current due to the overvoltage and protects the waveform shaping circuit 16. Further, the diode 22 improves the high speed property lost by inserting the resistor 21, and quickly passes the high level conduction signal output from the waveform shaping circuit 16 and supplies it to the switch circuit 8.

[0016]

As described above, according to the present invention, a resistor is connected between the output side of the gate circuit and the switch circuit, and a diode is arranged in parallel with this resistor with its cathode facing the switch circuit side. Since the connection is made, there is an effect that the gate circuit is protected from overvoltage noise and a high-quality pulse generator for a pulse laser can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a gate circuit in a pulse generator for a pulse laser according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional pulse generator for a pulse laser.

FIG. 3 is a configuration diagram of a gate circuit in the device.

FIG. 4 is a characteristic diagram for explaining the operation of the device.

FIG. 5 is an equivalent circuit diagram when the high-speed switching element in the device is OFF.

[Explanation of symbols]

 4 Capacitor 7 Laser Discharge Tube 8 Switch Circuit 12 Gate Circuit 21 Resistor 22 Diode

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number for FI Technical indication H03K 3/57 A 7328-5J 17/10 9184-5J (72) Inventor Tsutomu Inoue Tsukaguchi Honcho, Amagasaki 8-1-1, Mitsubishi Electric Corporation Itami Works

Claims (1)

[Claims] 1. A pulse generator for pulsed laser, wherein a switch circuit is turned on by a turn-on signal output from a gate circuit to discharge a capacitor, and the discharge current is supplied to a laser discharge tube. A pulse comprising a resistor connected between the output side of the circuit and the input side of the switch circuit, and a diode connected in parallel with the resistor with its cathode facing the switch circuit side. Laser pulse generator.