JP2768748B2 - Metal vapor laser equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a metal vapor laser device, and more particularly, to a laser medium using metal vapor as a laser medium to improve the discharge state and to improve laser oscillation output and efficiency. The present invention relates to a metal vapor laser device having improved characteristics.

(Prior Art) The configuration of a conventional metal vapor laser device will be described with reference to FIG. That is, a laser tube 2 as a heat-resistant discharge tube is accommodated in the center of the oscillation tube main body 1. A positive electrode 3 and a negative electrode 4 are disposed at both ends of the laser tube 2 so as to face each other. These electrodes 3 and 4 are supported by electrode support flanges 5 and 6, respectively, and are formed between the electrodes 3 and 4. A pulse bipolar discharge is performed in the discharge space 7 to be discharged. At the bottom of the laser tube 2 is disposed a metal vapor source 8 for producing metal vapor, such as copper particles.

Further, a heat insulating layer 9 made of a material such as alumina fiber is formed on the outer periphery of the laser tube 2, and a protective tube 10 made of quartz or the like is used to fix and protect the heat insulating layer 9 at a predetermined position.
Is provided on the outer periphery of the heat insulating layer 9. A vacuum insulated chamber is provided between the protective tube 10 and an external vacuum vessel 11 disposed outside the protective tube.
12 is formed. This vacuum insulation chamber 12 and laser tube 2
The inside discharge space 7 is connected to an exhaust device 13 so that the inside is maintained in a vacuum state.

A break tube 14 made of an insulating material such as ceramic or glass is interposed between the external vacuum vessel 11 and the electrode support flange 6 to insulate the positive electrode 3 and the negative electrode 4 and obtain a good discharge. Have been.

The operation of oscillating laser light is as follows. First, the exhaust device 13 is operated to exhaust the inside of the vacuum insulation chamber 12 and the discharge space 7, and then, a buffer gas such as Ne is introduced into the discharge space 7 from the buffer gas supply source 15. And maintain the inside at a constant pressure.

When the high voltage power supply 16, the pulse circuit 17, and the pulse drive power supply 18 are activated in this state, a pulsed high voltage is applied between the positive electrode 3 and the negative electrode 4, and discharge plasma is generated in the discharge space 7. The floating metal vapor collides with free electrons in the discharge plasma to excite the metal vapor, and when the excited metal vapor transitions to a low energy level, a laser beam of a predetermined wavelength is generated. The laser light generated in the discharge space 7 passes through the Brewster windows 19 and 20, and its amplitude increases while being reflected by the output mirror 22 and the total reflection mirror 23 constituting the laser light resonator 21. Oscillates from

An electric circuit for causing a high-voltage pulse discharge in the laser tube (discharge tube) 2 includes a hydrogen-filled thyratron 24 as a switching element for effectively supplying a high voltage from a high-voltage power supply 16, and a resistor. 25, capacitors 26 and 27, diode D, coil L and the like.

A hydrogen-filled thyratron having a hydrogen supply mechanism 28
Numeral 24 has a pulse drive power supply 18 for firing with a predetermined pulse and a reservoir power supply 29 for adjusting hydrogen concentration for normality of firing.

FIGS. 5 (a), 5 (b) and 5 (c) illustrate the operation of the hydrogen-filled thyratron 24 during laser oscillation in the metal vapor laser device configured as described above. FIG. 5 shows the operation state of the thyratron with respect to one pulse period with respect to the lapse of time of the grid voltage [FIG. 5 (a)], the anode voltage [FIG. 5 (b)], and the cathode current [FIG. 5 (c)]. Are roughly divided into four phases: a driving phase, a metastatic phase, a stationary phase, and a recovery phase. In the case of the hydrogen-filled thyratron 24, the temporal fluctuation of these four states depends on the concentration of hydrogen sealed in the thyratron. Therefore, in order to appropriately maintain the hydrogen concentration, a hydride such as titanium and a heater for heating the hydride are provided inside the thyratron as a reservoir, and the heater is heated to release hydrogen in a thermal equilibrium state. Has become.

(Problem to be Solved by the Invention) Usually, the voltage applied to the reservoir is presented by the manufacturer as a value in rated operation, and is set based on this value. If the voltage applied to the reservoir is inappropriate due to the relationship with the anode voltage, as shown in FIG. 6, the thyratron does not function as a switching element, and eventually damages the thyratron itself, leading to a laser oscillation stop state. Sometimes. In FIG. 6, the vertical axis represents the anode voltage (kV).
And the horizontal axis indicates the reservoir voltage (V). This is because hydrogen itself is adsorbed by the structure inside the thyratron and disappears little by little. Therefore, there is a problem that it is necessary to adjust the voltage applied to the reservoir each time depending on the degree of the anode voltage applied to the thyratron and the usage time of the thyratron. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a metal-based laser device which is capable of maintaining long-term stability of laser output, improving reliability, and saving labor.

[Configuration of the Invention] (Means for Solving the Problems) The present invention relates to a discharge tube in which a metal vapor source for generating metal vapor is arranged, a heat insulating material provided around the outer periphery of the discharge tube,
A pair of electrodes connected to both ends of the discharge tube, an electrode support flange supporting the pair of electrodes, a Brewster tube connected to the electrode support flange, and a pulse discharge in the discharge tube. In a metal vapor laser device having a hydrogen-filled thyratron as a switching element, a pulse drive power supply for driving the thyratron and a reservoir power supply for adjusting the hydrogen concentration, and a high-voltage power supply for applying a high voltage between the electrodes, By reading the anode voltage and grid voltage of the encapsulated thyratron and judging the fluctuation of the anode voltage fall time and the anode delay time, or by reading the anode voltage and the cathode current and judging the change in the internal loss, the hydrogen concentration adjustment is performed. An automatic setting device for determining a voltage to be supplied to the reservoir power supply is provided.

(Operation) The present invention reads the grid voltage and anode voltage waveforms applied to the hydrogen-filled thyratron, and transmits the data to a waveform reader. The transmitted data is compared with previous data to determine the presence or absence of a temporal variation, and the result is transmitted as data by the determination device. It consists of an automatic setting device that sets the reservoir voltage in steps of 0.05 to 0.2 V based on the data sent from this determination device, and it takes about from the setting of the reservoir voltage to the determination of the result by the determination device. Allow a time delay of several minutes.

According to the present invention, the voltage applied to the reservoir can be automatically set on the basis of the temporal variation of the anode voltage and the grid voltage applied to the thyratron, so that the operation can be performed in an optimum state. As a result, damage to the thyratron can be prevented, and long-term stability of laser output can be maintained and reliability can be improved. In addition, labor can be saved by automating complicated operations.

(Embodiment) An embodiment of the metal vapor laser apparatus according to the present invention is the first
This will be described with reference to the drawings.

The metal vapor laser device of this embodiment is the same as the conventional device shown in FIG. 4 except for the electric circuit system.
Therefore, in the figure, the same parts as those in FIG.

First, the voltage applied to the reservoir 28 of the hydrogen-sealed thyratron 24 is read out from the storage device 30 by reading the data stored during the operation, and set by the automatic setting device 32 via the determination device 31. Thereafter, the applied voltage is gradually increased by the high voltage power supply 16. The voltage applied from the high voltage power supply 16 becomes a higher voltage with a time constant determined by the coil L and the charging capacitor 27, and the charging capacitor 27 is charged. In this state, when a pulse is applied from the pulse drive power supply 18 to the grid G of the hydrogen-filled thyratron 24 at the repetition frequency kH, the hydrogen-filled thyratron 24 becomes conductive in synchronization with the repetition frequency, and is stored in the charging capacitor 27. Energy is applied to the oscillation tube main body 1 and discharge starts. At this time, the anode voltage and the grid voltage of the hydrogen-filled thyratron 24 are read by a waveform reading device 33 connected to the (A) and (B) terminals in the figure, and the data is transmitted to the judging device 31. The determination device 31 reads the previous data from the storage device 30 and compares it with the current data. The temporal variation is determined by the voltage drop time (see FIG. 5B) for the anode voltage and the anode delay time (see FIG. 5B) for the grid voltage. The determination is made based on the presence or absence of the difference shown in FIG. 5 (a). Based on the result of this judgment, the automatic setting device 32
And the reservoir applied voltage is changed in the range of 0.05 to 0.2V. In this case, it takes about 3 minutes for the hydrogen-filled thyratron to reach a steady state by changing the voltage applied to the reservoir. Will do.

In the case of the present embodiment, the presence or absence of the fluctuation of the anode delay time and the anode voltage fall time is used as the timing for changing the voltage applied to the reservoir. This is because thyratrons have their own characteristics, and the characteristics of the same type may be slightly different. It is conceivable that accuracy is low in the determination with one input signal, and a more reliable laser device can be realized by determining from the result of two input signals as in the present embodiment.

In the present invention, the voltage applied to the reservoir is changed in steps by the automatic setting device 32, the state of the thyratron at this time is read by the waveform reading device 33 with a delay of several minutes, and this is determined by the determining device 31, and the result is also determined. And a command is issued. In the above embodiment, the waveform reading device
The signals read at 33 are the grid voltage and the anode voltage, but these may be the anode voltage and the cathode current.

Thyratron has internal loss due to its resistance and inductance components. As shown in FIGS. 2 and 3, this loss changes depending on the increase or decrease of the fall time of the anode voltage.

2 and 3 show the anode voltage, the thyratron internal loss,
It shows a change state of the cathode current.

While the cathodic current is determined by components connected externally to the thyratron, the anodic voltage has been found to increase and decrease with the voltage applied to the thyratron reservoir.

If the reservoir applied voltage is not an appropriate value, the effect time of the anode voltage is prolonged as shown in FIG.

For this reason, the internal loss of the thyratron, which is determined by the product of the anode voltage and the cathode current, increases, resulting in heat generation of the thyratron and resulting in damage to the thyratron itself.

Therefore, the two signals may be read to calculate the internal loss of the thyratron, determine that a change has been recognized, and change the reservoir applied voltage. In this case, the internal loss of the thyratron is directly used as a judgment material, which is very effective from the viewpoint of protection of the thyratron, and can maintain the long-term stability of the laser device.

[Effects of the Invention] According to the present invention, the voltage applied to the reservoir can be automatically adjusted each time regardless of the degree of the anode voltage applied to the thyratron and the usage time of the thyratron. Therefore, it is possible to provide a metal vapor laser device in which long-term stability of laser output is maintained, reliability is improved, labor is saved, and the like.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a metal vapor laser device according to the present invention, and FIGS. 2 and 3 are characteristic curve diagrams for explaining the operation and effect of another embodiment of the present invention. FIG. 4 is a block diagram showing a conventional metal vapor laser device, and FIGS. 5 (a), (b) and (c) show grid voltage, anode voltage and cathode current applied to the thyratron in pulse form in FIG. Waveform diagrams each showing one cycle, FIG.
The figure is a characteristic diagram showing the range that can be applied to the reservoir in FIG. DESCRIPTION OF SYMBOLS 1 ... Oscillation tube main body 2 ... Laser tube 3 ... Positive electrode 4 ... Negative electrode 5, 6 ... Electrode support flange 7 ... Discharge space 8 ... Metal vapor source 9 ... Heat insulation layer 10 ... Protection tube 11 ... External vacuum vessel 12 ... Vacuum heat insulation Chamber 13 Exhaust device 14 Break tube 15 Buffer gas supply 16 High voltage power supply 17 Pulse circuit 18 Pulse drive power supply 19,20 Brewster window 21 Laser light resonator 22 Output mirror 23 Total reflection Mirror 24… Hydrogen-filled thyratron 25… Resistor 26,27… Condenser 28… Hydrogen supply mechanism 29… Reservoir power supply 30… Storage device 31… Judgment device 32… Automatic setting device 33… Waveform reading device

Claims (1)

(57) [Claims] A discharge tube in which a metal vapor source for generating metal vapor is arranged; a heat insulating material provided on an outer peripheral surface of the discharge tube; a pair of electrodes connected to both ends of the discharge tube; An electrode support flange supporting a pair of electrodes, a Brewster tube connected to the electrode support flange, a hydrogen-filled thyratron as a switching element for causing pulse discharge in the discharge tube, and a pulse drive for driving the thyratron In a metal vapor laser device having a power supply and a reservoir power supply for adjusting hydrogen concentration and a high-voltage power supply for applying a high voltage between the electrodes, the anode voltage and grid voltage of the hydrogen-filled thyratron are read, and the anode voltage fall time And the change in the anode delay time or by reading the anode voltage and the cathode current to determine the change in internal loss Metal vapor laser apparatus characterized by comprising an automatic setting unit which determines the voltage supplied to the hydrogen concentration adjustment reservoir supply.