JPH06164027A - Metal vapor laser apparatus - Google Patents

Abstract

PURPOSE:To provide a metal vapor laser apparatus which soves cost, obtains a stable laser output, and causes little trouble. CONSTITUTION:In a metal vapor laser apparatus, a metal vapor source 1 which generates metal vapor is installed at the inside, a discharge tube 5 filled with a buffer gas for discharge use is discharged and heated and a laser beam is generated. In the metal vapor laser apparatus, a flow-rate regulating valve 19 and an automatic opening and shutting valve 26 are interposed and installed inside a flow passage which connects the discharge tube 5 to a vacuum evacuation pump 20 which evacuates the buffer gas for discharge use at its inside. The metal vapor laser apparatus is provided with a manometer 18 which measures the pressure of the buffer gas inside the discharge tube 5 and with a controller 27 which operates the automatic opening and shutting valve 26 by a signal from the manometer 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal vapor laser device, and more particularly to a metal vapor laser device which automatically and constantly controls the pressure of a discharge buffer gas filled in a discharge tube.

[0002]

2. Description of the Related Art A conventional general metal vapor laser device is
For example, it was configured as shown in FIG.

That is, in FIG. 1, a plurality of metal vapor sources 1
An anode 3 and a cathode 4 are connected to both ends of a cylindrical ceramic tube 2 installed inside by a joining member 2a to form a discharge tube 5. An electrode flange 6 is provided on each of the anode 3 and the cathode 4 in the discharge tube 5. This electrode flange 6 is attached and fixed to an electrode support flange 10 interposed between a body 7 and an insulating tube 8 surrounding the discharge tube 5 and a Brewster tube 9,
Thereby, the respective electrodes of the anode 3 and the cathode 4 are fixed to the electrode support flange 10 via the electrode flange 6.

The outer peripheral surface of the discharge tube 5 is surrounded by a heat insulating material 11, and the outer circumference of the heat insulating material 11 is covered with an insulating tube 8 having a body 7 and an insulating tube flange 12. Each electrode support flange 10 has a pair of Brewster tubes 9
Is connected to the opening of this Brewster tube 9,
The windows 13 are attached, and the output mirror 14 and the total reflection mirror 15 are arranged outside the windows 13 to form a laser resonator.

In FIG. 2, a gas supply pipe 16 for supplying, for example, neon (Ne) gas as a discharge buffer gas is connected to one of the Brewster pipes 9 shown on the left side, and the other Brewster pipe shown on the right side. A gas exhaust pipe 17 is connected to the pipe 9. This gas exhaust pipe 17
Is equipped with a pressure gauge 18 on the way,
It is connected to a vacuum exhaust pump 20 via a flow rate adjusting valve 19. The electrode support flange 10 located on the left side
A high DC voltage is applied between the insulating tube flange 12 and the insulating tube flange 12.

In the figure, reference numeral 21 is a charging capacitor, 22 is an intermediate capacitor, 23 is a resistor, 24 is a thyratron, and 25 is a diode.

In the metal vapor laser device having the above structure, the laser is oscillated as follows.

First, in the discharge tube 5 in which the metal vapor source 1 is arranged, from the gas supply tube 16 to the discharge buffer bath,
For example, neon gas is supplied. Next, a high voltage is applied between the anode 3 and the cathode 4 provided at both ends of the ceramic tube 2 to form discharge plasma. Then, the discharge plasma heats the ceramic tube 2 to a high temperature, and vaporized metal particles (metal vapor) serving as a laser medium are generated from the metal vapor source 1. Further, this metal vapor diffuses in the ceramic tube 2 and is excited by free electrons in the discharge plasma in the ceramic tube 2. When the excited metal vapor makes a transition to a low energy unit, it emits laser light.

As described above, the laser oscillation is carried out by performing photovoltage discharge in the discharge buffer gas to form plasma, but the discharge resistance at the time of this discharge is large due to the pressure of the charge buffer gas. Since it changes, it is necessary to stably control the pressure of the discharge buffer gas in the discharge tube 5.

Therefore, when the laser device is operated, the supplied buffer gas flow rate is controlled to be constant, and the buffer gas flow rate exhausted by the flow rate adjusting valve 19 connected to the vacuum exhaust pump 20 for exhausting the discharge buffer gas is also adjusted. It is generally performed to control it to be constant.

The temperature of the components such as the discharge tube 5 is room temperature at the start of the operation of the laser device, and the temperature of the discharge buffer gas is raised to 1500 ° C. at the time of the laser oscillation operation. It will change. Therefore, in order to maintain the buffer gas pressure in the discharge tube 5 constant, the flow rate adjusting valve 19 is frequently adjusted manually or automatically adjusted using an electric flow rate adjusting valve.

[0012]

However, the laser device is generally used in a state in which a large number of devices are combined, and in manual control, many drivers are required, and in addition, there are problems such as control operation errors. May occur.
Further, when the electric flow rate control valve is used, as described above, since it is connected to the laser device that performs high-voltage discharge, there is a possibility that malfunction or failure due to malfunction or dielectric breakdown failure of electrical parts may occur. . That is, when a manual flow rate adjusting valve is used, it causes a rise in cost and instability of the laser output, and when an electric flow rate adjusting valve is used, it causes a failure. was there.

In view of the above, it is an object of the present invention to provide a metal vapor laser device which can obtain a stable laser output at a low cost and has few failures.

[0014]

In order to achieve the above object, a metal vapor laser device according to the present invention is a discharge tube in which a metal vapor source for generating metal vapor is installed and a discharge buffer gas is filled. In a metal vapor laser device for discharging and heating to generate laser light, a flow rate adjusting valve and an automatic opening / closing valve are provided in a flow path connecting the discharge tube and a vacuum exhaust pump for exhausting the discharge buffer gas inside the discharge tube. It is equipped with a pressure gauge for measuring the buffer gas pressure in the discharge tube and a controller for operating the automatic opening / closing valve according to a signal from the pressure gauge.

[0015]

According to the present invention having the above structure, the pressure of the discharge buffer gas introduced into the discharge tube is measured by the pressure gauge, and the automatic opening / closing valve connected to the vacuum exhaust pump is controlled by the pressure gauge through the controller. Control is performed, that is, when the pressure value measured by the pressure gauge exceeds the preset upper limit pressure value, the automatic opening / closing valve is opened, and the value measured by the pressure gauge is equal to or lower than the preset lower limit pressure value. By performing control to close the automatic open / close valve when it falls to a low level, it is possible to automatically control the discharge buffer gas pressure in the discharge tube of the metal vapor laser device to be constant by inexpensive opening / closing operation of the automatic open / close valve. .

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIG.

The same or corresponding parts as those of the conventional example shown in FIG.

In FIG. 1, the metal vapor deposition laser device includes
The anode 3 is connected to both ends of the ceramic tube 2 via the connecting members 2a.
And a discharge tube 5 constituted by connecting the cathodes 4 so as to face each other. A pulse secondary discharge is generated between these electrodes 3 and 4. A heat insulating material 11 is arranged on the outer circumference of the ceramic tube 2, and a metal body 7 is arranged on the outer circumference thereof.

A pair of Brewster tubes 9 are connected to the outsides of the electrodes 3 and 4 at both ends of the discharge tube 5, and one of the Brewster tubes 9 located on the left side is connected to a gas supply system. A gas exhaust pipe 17 is connected to each of the brewer pipe 16 and the other Brewster pipe 9 located on the right side.
Further, a pressure gauge 18 for measuring the pressure of the discharge buffer gas in the discharge tube 5 is provided, and a gas exhaust pipe 17 connecting the discharge tube 5 and the vacuum exhaust pump 20 has a flow rate adjusting valve 19 and an automatic opening / closing valve. And 26 are sequentially interposed. Further, there is provided a controller 27 which operates the automatic open / close valve 26 in response to a signal from the pressure gauge 18 and thereby controls the pressure of the discharge buffer gas in the discharge tube 5.

The gas supply pipe 16 supplies a discharge buffer gas such as neon gas into the discharge tube 5, and the gas exhaust pipe 17 discharges the discharge buffer gas inside the discharge tube 5 to the outside. It is for doing.

An output mirror 14 and a total reflection mirror 15 are arranged outside the window 13 of the Brewster tube 9, respectively, and thereby a laser oscillator is constituted.

The above-mentioned pulsed two-pole discharge supports the anode 3 and the cathode 4 and causes an electric current to flow through them.
This is done by a pulsed high voltage power supply connected to zero. This pulse high voltage power supply includes a charging capacitor 21, an intermediate capacitor 22, a resistor 23, a thyratron 24 and a diode 2.
It is composed of a circuit including 5 and the like.

This pulse high-voltage power supply has a charging capacitor 2
The electric charge charged to 1 ignites the thyratron 24 so that a discharge current is generated with a rise time of approximately 10 ⁻⁷ seconds or less. The thyratron 24 is a pulse discharge switching element. The pulse high voltage generated here is, for example, a voltage of several KV to several tens of KV and a repetition frequency of several KHz to several tens of KHz.

In the figure, symbol A is an anode terminal, C is a cathode terminal, and G is a trigger signal introduction terminal. The other configuration is the same as that of FIG. 2, and therefore its explanation is omitted.

Next, the operation of the above embodiment will be described.

First, the vacuum exhaust pump 20 is operated,
The inside of the discharge tube 5 is evacuated, and after the evacuation, a discharge buffer gas such as helium gas is injected from the gas supply pipe 16. The buffer gas pressure in the discharge tube 5 increased by the injection of the discharge buffer gas is measured by the pressure gauge 18, and when the measured value exceeds a preset upper limit pressure value, the controller 27 causes the automatic opening / closing valve. Open 26. This automatic open / close valve 2
By opening 6, the discharge of the discharge buffer gas is performed at a discharge amount that slightly exceeds the supply amount of the buffer gas, and the buffer gas pressure in the discharge tube 5 gradually decreases. And the pressure gauge 18
The controller 27 closes the automatic opening / closing valve 26 when the value measured by (1) has fallen below the preset lower limit pressure value.
By closing the automatic opening / closing valve 26, the buffer gas pressure in the discharge tube 5 starts to rise again. Thus, by opening and closing only the automatic opening / closing valve 26, the buffer gas pressure in the discharge tube 5 can be controlled to be constant.

Next, the pulse high voltage power supply is operated to generate plasma in the discharge tube 5, and the temperature is raised to a temperature at which the metal vapor source 1 can generate metal vapor by the plasma. The temperature required for laser oscillation is, for example, about 1500 ° C. when the metal vapor source 1 is copper. By maintaining this state, the metal vapor is uniformly distributed in the ceramic tube 2.

Free electrons in the plasma collide with the metal vapor to excite the metal vapor, and eventually the ceramic tube 2 is in a population inversion state. In this state, laser light is generated when the excited metal vapor makes a transition to a low energy unit. The laser light generated in the ceramic tube 2 passes through the window 13 and is increased in power while being reflected by the output mirror 14 and the total reflection mirror 15 that form the laser resonator, and eventually the power is increased from the output mirror 14. The extracted laser light reaches a sufficient output.

As described above, according to this embodiment, the buffer gas pressure in the discharge tube 5 of the metal vapor laser device is automatically controlled to be constant by opening / closing the relatively inexpensive automatic opening / closing valve 26 to stabilize the operation. A laser output can be obtained. Further, since it is the opening / closing operation of the on-off valve, there is no risk of failure or malfunction, and it can be used stably for a long time.

As another embodiment, a manual flow rate adjusting valve (not shown) whose opening is changed is installed in parallel with the flow rate adjusting valve 19 and the automatic opening / closing valve 26 of the above embodiment, and the automatic opening / closing valve 26 is closed. When the buffer gas pressure in the discharge tube 5 is increased, a small amount of discharge buffer gas is exhausted through the manual flow rate adjusting valve provided in parallel and set to a small opening to suppress the increase rate of the buffer gas pressure. By increasing the opening / closing control time interval of the automatic opening / closing valve 26, it is possible to further stabilize the laser output.

Further, a plurality of manual flow rate adjusting valves and automatic open / close valves having different degrees of opening are installed in parallel with the flow rate adjusting valve 19 and the automatic open / close valve 26, and the buffer gas pressure in the discharge tube 5 and the discharge for injection are provided. It is also possible to operate the laser device while changing the flow rate of the buffer gas.

[0032]

As described above, according to the present invention,
The buffer gas pressure in the discharge tube can be controlled automatically and almost constantly without fear of failure or malfunction.
This makes it possible to obtain a stable laser output for a long time. Moreover, since it is only necessary to add a relatively inexpensive device, there is an effect that the structure is relatively simple and the manufacturing cost is low.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention together with a circuit diagram.

FIG. 2 is a view corresponding to FIG. 1 showing a conventional example.

[Explanation of symbols]

 1 Metal Vapor Source 2 Ceramic Tube 3 Anode 4 Cathode 5 Discharge Tube 6 Electrode Flange 10 Electrode Support Flange 16 Gas Supply Pipe 17 Gas Exhaust Pipe 18 Pressure Gauge 19 Flow Control Valve 20 Vacuum Exhaust Pump 21 Charge Capacitor 24 Thyratron 26 Automatic Open / Close Valve 27 Controller

Claims (1)

[Claims] 1. A metal vapor laser apparatus for internally generating a metal vapor source for generating metal vapor and for discharging and heating a discharge tube filled with a discharge buffer gas to generate a laser beam. A pressure gauge for interposing a flow rate adjusting valve and an automatic opening / closing valve in a flow path connecting with a vacuum exhaust pump for exhausting an internal discharge buffer gas, and a pressure gauge for measuring the buffer gas pressure in the discharge tube, and this pressure gauge. A controller for operating the automatic on-off valve according to a signal from the metal vapor laser device.