JPH04196496A - Controller for co2 laser oscillator - Google Patents

Abstract

PURPOSE:To reduce the amount of consumption of laser gas without lowering oscillating efficiency by operating a control valve based on compared values between a set point and a detected value by an O2 concentration sensor within a chamber. CONSTITUTION:O2 concentration in an oscillator chamber is detected by an O2 concentration sensor 8, and its detected value is input to a comparative processing unit 9 and compared to a set point previously input. Based on the results of the comparison, a control valve of a mixed gas supply way is operated and mixed gas supply to the chamber 3 is interrupted or continued. When the supply is interrupted, O2 concentration rises up gradually. When the supply is started, the O2 concentration is lowered by the new mixed gas. By doing this, the gas consumption is controlled in conformity with the running situation of the oscillator and the gas consumption is reduced within the range not adversely affecting the oscillating efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control device for efficient operation of a CO2 laser oscillator.

Conventional technology The C Oe laser oscillator conventionally used is CO9,
Gases supplied from respective gas cylinders of N, , and He are mixed in a gas mixing device 1 at a constant mixing ratio, for example, CO7.Nt:He=1+12+15, as shown in FIG. 5, and sent to the oscillator chamber 3. Oscillator chamber 3
Inside are a discharge electrode that performs glow discharge to give excitation energy to CO2 molecules, a blower to circulate and cool the gas, a heat exchanger, an optical resonator to stimulately emit and amplify the light generated from COt molecules, etc. This is a well-known one that includes. Electric power is supplied to the discharge electrode in the chamber 3 by the radiation source 2 which receives a laser output command, and glow discharge is performed. In order to maintain this glow discharge stably, chamber 3
A pressure sensor 6 is provided to detect the internal pressure, and this detected value a1 is inputted to a comparator 7 and set as a pressure set value a.
0 and controls the control valve 4 provided in the exhaust path to the vacuum pump 5 to maintain the chamber 3 at a vacuum of several tens of torr.

Problems to be Solved by the Invention In this conventional device, the vacuum inside the chamber 3 is maintained at a predetermined value. However, when a glow discharge occurs in the oscillator chamber 3, energy is given to CO2 molecules, so CO2→
A reaction of CO+(1/2)0* occurs, causing a discharge current and 0. The concentration increases as shown in FIG.

There is a proportional relationship between the discharge current and the laser output, and the laser output is controlled by the discharge current, so when the laser output is small, the 0. The concentration is low, and when the laser power is high the O2 concentration in the oscillator chamber is high. There is a problem that as the O2 concentration increases, the oscillation efficiency decreases.

In addition, at the discharge current corresponding to the maximum laser output peculiar to the oscillator, it was necessary to suppress the O2 concentration below a level that does not affect the oscillation efficiency, so the gas consumption was reduced by the discharge current (
As shown in FIG. 7, the value remains constant regardless of the laser output (laser output), which may be uneconomical.

The present invention was made in view of the above-mentioned problems of the conventional technology, and its purpose is to reduce the consumption of laser gas without reducing the oscillation efficiency, thereby reducing the running cost of a C○ laser oscillator. The present invention aims to provide a control device for the following.

Means for Solving the Problems To achieve the above-mentioned objects, the present invention provides
an O7 concentration sensor that detects 7a degrees; a control valve that opens, closes, or adjusts the mixed gas supply flow path to the chamber;
, a comparison calculation device that compares the detected value of the a degree sensor with a set value and operates the control valve based on this comparison value.

The O1 concentration in the active oscillator chamber is detected by the O2 concentration sensor, and the detected value is input to a comparator and compared with a previously input set value. Based on the comparison result, the control valve of the mixed gas supply channel is operated to interrupt the mixed gas supply to the chamber. When the supply is cut off, the O7 concentration gradually increases, and when the supply starts, the O7 concentration decreases due to the new mixed gas.

Example Examples thereof will be described below with reference to FIGS. 1 to 4.

The same parts as in FIG. 5 of the conventional configuration are designated by the same reference numerals, and the explanation thereof will be omitted.

A concentration sensor 8 is added to detect the O2 concentration in the chamber 3, and its output is input to a comparator 9. This comparison calculation device 9 calculates the pressure setting value a. In addition, there is a maximum of 0,111 degrees that does not adversely affect the oscillation efficiency.
The O2 concentration level b2, which is a little lower than level I, is set in advance and inputted as the O2 concentration set value. Then, in the calculation device, the detected value ai of the pressure sensor 6 and the o2 concentration *
Detected value bi of sensor 8 and respective set value ao+b++
The comparison operation with b2 is performed by time division. Based on the comparison result between the detected value of the O2 concentration sensor 8 and the set value, the control valve 10 provided in the supply flow path from the gas mixing device 1 is opened or closed.

The system configured as described above will be explained based on FIG. 3 showing the flow of control.

Laser oscillator discharge power supply with two people and gas mixing device ftl
More mixed gas is supplied, and as the discharge current (laser output) increases, the O2 concentration increases as shown in FIG. 2, and the mixed gas pressure in the chamber 3 also gradually increases. A control operation is started together with the power supply person, and in step S1, the pressure in the chamber 3 is detected by the pressure sensor 6, and the detected value ai is input to the comparison calculation device 9, and in step S2, it is previously input to the device by time-sharing calculation. The set values a0 and ai are compared. If ai≧aO or YES, the control valve 4 is opened in step S3. If No in step S2, the control valve 4 is closed in step S4, and the process moves to step Sl to repeat the control. On the other hand, in the comparison calculation device 9, the following fringe calculation or the above calculation is performed alternately at times that do not overlap in time division. That is, step S y,! '
, 1, the detection value b detected by the O2 concentration sensor 8
1 or the set value bl corresponding to level I>level ■ is inputted to the comparison calculation device 9 and inputted in advance in step S12.
>t), then the detected value bi or b1≦bi is compared. As the discharge current rises, the concentration also rises by 02a degrees, and since the concentration is initially lower than level 1, the answer is NO, and in step S13, the control valve 10 is closed or remains closed. Again in step S11, the detected value is input to the comparison calculation device 9, and a comparison is made in step S12, and this loop is repeated for a while. Since no mixed gas is supplied to the chamber 3, the concentration in the chamber gradually increases, and finally the answer is YES in step S12, and the control valve 10 is opened in step S14. When the control valve lO is opened, a new mixed gas is supplied from the mixed gas control device I, and the concentration gradually decreases or does not decrease immediately at step S1.
5, detection value bi and level slightly lower than level i■
b2 is compared, and if b2≦b1 or YES, the process moves to step S14, the control valve 10 continues to open, and this loop is repeated. If the O7 concentration decreases due to the opening of the control valve 10 and the answer is NO in step S15, the process moves to step S13 where the control valve 10 is closed and step S11. SI2
The process moves to step Sll.

12.13 loop is repeated. Then, as shown in FIG. 2, the 02 density progresses in a waveform between levels I and H, and becomes a stable density within the set value. However, since the operation in which a sufficient discharge current is supplied cannot always be maintained, the discharge current also becomes small at low output, and the mixed gas consumption can be kept low, resulting in the consumption as shown in Figure 4. Become.

In this embodiment, it is also possible to use a flow rate control valve that either opens and closes the control valve or does not open and close the control valve.

Effects of the Invention As configured as described above, the present invention has the following effects.The gas consumption is controlled in accordance with the operating conditions of the oscillator, and the gas consumption is reduced to the extent that the oscillation efficiency is not adversely affected. Ru. In other words, running costs can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a control block diagram of the present invention, Fig. 2 is a diagram showing the relationship between discharge current and 02 concentration of the present invention, Fig. 3 is a control flow chart, and Fig. 4 is a diagram showing the discharge current and gas consumption of the present invention. FIG. 5 is a conventional control block diagram, FIG. 6 is a diagram showing the relationship between discharge current and 02 concentration, and FIG. 7 is a diagram showing conventional gas consumption.

Claims (1)

[Claims] (1) In a CO_2 laser oscillator that generates a laser beam by keeping the inside of the laser oscillator chamber at a constant pressure and causing glow discharge to occur, there is an O_2 concentration sensor that detects the O_2 concentration in the chamber, and a mixed gas supply flow to the chamber. A CO_2 laser oscillator characterized in that it includes a control valve that opens, closes or adjusts a passage, and a comparison calculation device that compares a detected value of the O_2 concentration sensor with a set value and operates the control valve based on this comparison value. Control device.