JPH0373582A - Metal vapor laser device - Google Patents

Abstract

PURPOSE:To automate laser generating operation by detecting a current flowing to a resistor connected in parallel with a discharge tube, turning OFF a high voltage power source if a current value exceeds a set value, and so controlling a valve as to replace buffer gas in the tube. CONSTITUTION:Discharging buffer gas is supplied from a gas cylinder 25 in which buffer gas is filled into a ceramic tube 2 through a gas introduction valve 23, a pulse high voltage of a high voltage pulse power source circuit 111 is applied to an anode 8 and a cathode 9, a discharge part 4 in the tube 2 is discharged to heat the tube 2 by a discharge plasma. In this case, when impurities of a material are introduced into the discharge gas during discharge heating, discharge starting voltage of a laser tube 1 is abnormally raised. In this case, a voltage across a resistor 15 connected in parallel with the tube 1 is increased, and a current rises. An abnormal signal is sent to a processor 21 by a current detection circuit 20 for detecting the abnormal current, a high voltage power source 12 is turned OFF, and the valve 23 and a gas discharge valve 24 are so controlled as to replace the gas in the tube 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a metal vapor laser device, and particularly to a metal vapor laser device in which laser start-up operation is automated.

(Prior art) For example, metal vapor laser devices used for laser processing, photoreaction processes, selective excitation ionization of isotope atoms, etc.
First, the laser tube is sufficiently evacuated to create a vacuum, and then filled with buffer gas (usually Ne or He, etc.) and heated by discharge to sufficiently heat the laser tube. After the metal inside the laser tube is vaporized, laser oscillation begins. It is something to do. At this time, evacuation of the laser tube and filling of buffer gas were dependent on human labor.

In addition, the discharge state is visually monitored, and if operation is continued while the discharge state is poor, electrical parts and laser tubes are often damaged.

If the discharge condition is poor, the operation must be stopped, the laser tube must be sufficiently evacuated, and then the buffer gas must be filled again.

(Problems to be Solved by the Invention) In other words, in the conventional metal vapor laser device described above, evacuation of the laser tube at the time of start-up, filling of buffer gas, and monitoring of the discharge state are dependent on human labor, and usually During the time required to start up the laser equipment (approximately 1 to 2 hours), a person must be present at the laser equipment to monitor the operating status. If this monitoring is not carried out, the laser tube may be destroyed or electrical components may be damaged. There was a problem that caused it to happen.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a metal vapor laser device in which laser start-up operation is automated.

[Structure of the invention]

(Means for Solving the Problems) A metal vapor laser device according to the present invention supplies a discharge buffer gas through a valve to a discharge tube containing metal particles, and applies a high voltage to the discharge tube from a high-voltage power supply. A metal vapor laser device that discharges a metal vapor laser includes a resistor connected in parallel to the discharge tube, a current detecting means for detecting the current flowing through the resistor, and a current value of the current detecting means exceeding a set value. The apparatus is equipped with a control means that inputs a signal to that effect to turn off the high-voltage power supply and controls valve operation so as to replace the buffer gas in the discharge tube.

(Function) In the present invention having the above configuration, when discharge starts and the temperature of the discharge tube rises, impurities adsorbed by the components inside the discharge tube flow into the discharge gas, and the discharge of the discharge tube starts. The voltage will rise.

If this discharge starting voltage rises and exceeds a predetermined voltage, the insulation inside the discharge tube will break down and the discharge tube will be destroyed, or the electrical components that apply high voltage to the discharge tube will also be destroyed. Become.

Before such a state occurs, the value of the current flowing through the resistor connected in parallel with the discharge tube increases. When this current value exceeds a certain set value, the high-voltage power supply is turned off and the buffer gas inside the discharge tube is replaced.By controlling the valve operation, startup operation is performed without destroying the discharge tube, etc. becomes possible.

(Example) The present invention will be described below based on illustrated embodiments.

FIG. 1 shows a metal vapor laser device according to an embodiment of the invention. As shown in this figure, a laser tube 1 as a discharge tube
In this example, a discharge section 4 is formed by placing metal particles 3 in a ceramic tube 2 formed into a circular tubular shape. A heat insulating material 5 is coaxially disposed outside the ceramic tube 2 in a cylindrical shape, a glass tube 6 is disposed around the heat insulating material 5, and an O-ring 7 provides a gas seal with the outside. Further, an anode 8 and a cathode 9 are disposed facing each other near both ends of the ceramic tube 2, and in order to apply a high voltage between these picture electrodes 8 and 9, the high voltage side and the low voltage side are divided by an insulation break 10. There is.

A high voltage pulse power supply circuit 11 for applying high voltage pulses is connected to the laser tube 1, and this pulse power supply circuit 11 includes a high voltage power supply 12, a choke coil 13, a diode 14,
It has a charging circuit configured by sequentially connecting a charging capacitor 15 and a resistor 16, and a discharging circuit consisting of a thyratron 17 as a switching element, a trigger circuit 18, and a discharging capacitor 19, and has a charging circuit configured by sequentially connecting a charging capacitor 15 and a resistor 16. A charging capacitor 15 is charged with voltage by a choke coil 13, a diode 14, and a resistor 16.

Here, when a voltage of mainly 5 to 15 KV is applied to the high voltage power supply 12 and a repetitive trigger signal of 1 to 10 KHz is applied from the trigger circuit 18 to the thyratron 17, the voltage applied from the high voltage power supply 12 is applied to both ends of the thyratron 17. A voltage twice that of is applied. This high voltage causes the laser tube 1 to be intermittently discharged, and the metal particles 3 disposed within the ceramic tube 2 are heated by the action of the heat insulating material 50. In this way, the metal particles 3 come into contact with the discharge plasma, the ceramic tube 2 is heated to a very high temperature, and the metal particles 3 are evaporated, thereby generating metal vapor that becomes the laser medium.

The current flowing through the resistor 16 connected in parallel with the laser tube 1 is detected by a current detection circuit 20 as a current detection means, and when this current value exceeds a certain set value, a signal to that effect is sent as a control means. The data is sent to the processor 21 of. Further, the pressure in the laser tube 1 is measured by a pressure gauge 22, and when the degree of vacuum in the laser tube 1 exceeds a predetermined value, a signal to that effect is sent to the processor 21. This processor 21 sends an on/off signal for the high voltage power supply 12, and also sends an opening/closing signal and a signal for adjusting the opening degree to the gas introduction valve 23 and the gas exhaust valve 24.

On the other hand, a discharge buffer gas from a gas cylinder 25 filled with a buffer gas such as Ne gas is supplied to the discharge section 4 inside the laser tube 1 via a pressure reducing valve 26 and a gas introduction valve 23. The gas is evacuated by driving the vacuum pump 27 and opening the gas exhaust valve 24.

Next, the operation of this embodiment will be explained.

A pressure reducing valve 26 and a gas introduction valve 23 are connected to a gas cylinder 25 filled with a buffer gas such as Ne gas in the ceramic tube 2.
A discharge buffer gas is supplied, and a pulsed high voltage from a high-voltage pulse power supply circuit 111 is applied to the anode 8 and cathode 9 to cause discharge in the discharge section 4 within the ceramic tube 2. The ceramic tube 2 is heated by the discharge plasma generated during this discharge, and for example, in the case of a copper vapor laser, the axial middle part of the ceramic tube 2 is heated to a temperature of 1450 to 1500 degrees Celsius, which is optimal for laser oscillation.
is heated to.

By the way, when the heat insulating material 5, the ceramic tube 2, etc. are new, or immediately after metal particles 3 such as copper have been added, impurities (mainly water) from the above components may be present in the discharge gas during discharge heating. The operation of the processor 21 in this case where the discharge starting voltage of the laser tube 1 abnormally increases will be explained based on the flowchart shown in FIG.

That is, when the firing voltage of the laser tube 1 abnormally increases, the voltage across the resistor 16 connected in parallel with the laser tube 1 also increases, and the current flowing through the resistor ]-6 increases. The current detection circuit 20 that detects this abnormal current causes the processor 2 to
1, the processor 21 sends an abnormal signal to the high voltage power supply 12.
Generate a signal to turn off (steps 101, 102)
. Thereafter, the gas introduction valve 23 for introducing the discharge buffer gas is closed, the gas exhaust valve 24 is fully opened, and the impurity gas in the laser tube 1 is evacuated by the vacuum pump 27 (steps 103 and 104).

When the degree of vacuum reaches a predetermined value or more by the pressure gauge 22, a signal indicating the degree of vacuum is sent to the processor 21, and the processor 21 receives the signal and adjusts the opening degree of the gas exhaust valve 24 to adjust the exhaust flow rate to several /h (step 105
．． 106). Thereafter, the gas introduction valve 23 is opened to supply Ne gas into the laser tube 1 (step 107).

When the pressure gauge 22 indicates that the Ne pressure reaches the set value, a signal is given to the processor 21 again to turn on the high voltage power supply 12 again and start discharging (steps 108 and 109). When the above operation is automatically repeated two to three times, impurities are eliminated from the laser tube 1, and laser oscillation becomes possible.

In this way, when the current value of the current detection circuit 20 exceeds a set value, the processor 21 receives a signal to that effect and turns off the high voltage power supply 12, and also replaces the discharge buffer gas in the laser tube 1. The operation of the gas introduction valve 23 and the gas discharge valve 24 is controlled.

〔Effect of the invention〕

As explained above, according to the present invention, evacuation of the discharge tube at startup, buffer gas filling, and monitoring of the discharge state are automated and labor-saving, thereby preventing damage to the discharge tube and electrical components. It has the effect of being able to prevent this.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view showing the overall structure of an embodiment of a metal vapor laser device according to the present invention, and FIG. 2 is a flowchart showing the operation of a processor in the embodiment. 1... Laser tube (discharge tube), 2... Ceramic tube,
3... Metal particles, 8... Anode, 9... Cathode, 11
...High voltage pulse power supply circuit, 12...High voltage power supply, 16
...Resistor, 20...Current detection circuit (current detection means)
, 21... Processor (control means) 24... Gas exhaust valve.

Claims (1)

[Claims] A metal vapor laser device in which a discharge buffer gas is supplied to a discharge tube containing metal particles through a valve, and a high voltage is applied to the discharge tube from a high-voltage power source to discharge the discharge tube,
A resistor connected in parallel to the discharge tube, a current detecting means for detecting the current flowing through the resistor, and a signal indicating that when the current value of the current detecting means exceeds a set value is inputted to the high voltage. A metal vapor laser device comprising: control means for controlling valve operation to turn off the power and replace buffer gas in the discharge tube.