JPH0391274A - Gas laser oscillator - Google Patents

Abstract

PURPOSE:To detect the optimum replacement timing of a filter and to maintain laser oscillation stably by allowing an alarm to be displayed when the pressure difference between pressure sensors arranged in front and the rear of the filter exceeds a set value, and at the same time by opening a bias valve little by little as the difference of the pressure sensor increases. CONSTITUTION:Pressure sensors 21 and 22 are attached in front and the rear of a filter 10 and they measure gas pressure within a circulation path 7 to output measured valves P1 and P2, respectively. An arithmetic unit 23 obtains a difference Pa by subtracting the measured value P2 from the measured value P1. A comparator 24 compares the difference Pa with a previously set value P4 and generates an alarm signal Sa when the different Pa exceeds a set value Pr. A display device 25 displays a message prompting replacement of the filter 10 based on this alarm signal Sa. Also, the arithmetic unit 26 calculates a difference by subtracting the set value Pr from the difference Pa, and then outputs 0 if the difference ( Pa-Pr) is equal to 0 or less while outputting a signal which is proportional to the value as a valve opening signal Pb when the difference is positive. A driver 27 amplifies the valve opening signal Pb, thus opening a valve 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a gas laser oscillator in which a filter is provided in a laser gas circulation path, and particularly to a gas laser oscillator that does not suffer from problems due to clogging of the filter.

[Conventional technology]

In carbon dioxide laser oscillators used for metal processing and the like, laser gas within a discharge tube is constantly circulated through a cooler in order to improve oscillation efficiency.

On the other hand, this laser gas contains various types of dust, such as dust mixed in when the laser gas is introduced, dust stuck inside the piping of the circulation passage, and droplets of lubricating oil from the blower, which may damage the rear mirror, output mirror, etc. optical components may become contaminated.

For this reason, a filter is inserted in the middle of the circulation path to remove dust. This filter is replaced, for example, at regular intervals.

[Problem to be solved by the invention]

However, the amount of dust adsorbed by the filter varies depending on the environment and operating conditions, and in the past, the filter was not always replaced at the optimal time.

If the filter is replaced too early, it is economically wasteful. Conversely, if the filter is replaced too late, the filter becomes clogged, the ventilation resistance increases, the laser gas flow rate decreases, and stable laser oscillation cannot be achieved.

The present invention has been made in view of these points, and an object of the present invention is to provide a gas laser oscillator that can detect the optimal time to replace a filter.

Another object of the present invention is to provide a gas laser oscillator that can maintain stable laser oscillation even if the filter replacement time is delayed.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a gas laser oscillator in which a filter for removing impurities is provided in a laser gas circulation path, and a gas laser oscillator that measures the gas pressure at a position immediately before and after the filter in the circulation path. monitoring means for outputting a predetermined alarm signal when the difference between the measured values of the first and second pressure sensors becomes a set value or more; A gas laser oscillator is provided, characterized in that the gas laser oscillator has a display means for displaying an alarm prompting replacement of the filter, and the gas laser oscillator is provided with a filter for removing impurities in a circulation path of the laser gas, wherein the circulation path a bypass passage connecting the front and back of the filter, a valve provided in the bypass passage to shut off the flow of the laser gas, and a gas pressure at a position immediately before and after the filter in the circulation passage. first and second pressure sensors; signal generating means for generating a predetermined valve opening signal when the difference between the measured values of the first and second pressure sensors becomes a set value or more; and the valve opening signal Accordingly, there is provided a gas laser oscillator characterized by having a valve opening means for opening the valve at a predetermined opening degree.

[Effect]

As the clogging of the filter progresses, the pressure difference before and after the filter increases, so by detecting this with a pressure sensor, the degree of clogging can be quantitatively monitored. When a predetermined pressure difference is reached, an alarm is displayed and the bypass valve is gradually opened to avoid reducing the overall flow rate of the laser gas.

〔Example〕

Hereinafter, one embodiment of the present invention will be briefly described with reference to the drawings.

FIG. 1 is a block diagram of a carbon dioxide laser oscillator according to an embodiment of the present invention. In the figure, arrows indicate the flow of laser gas. When a high frequency voltage of, for example, 2 MHz and 2 to 3 KV is applied from a high frequency power source 3 between electrodes 2a and 2b provided on the outer wall of the discharge tube 1, a discharge occurs and the laser gas inside is excited. The rear mirror 4 is a mirror made of germanium (Ge) with a reflectance of 99.5%, and the output mirror 5 is a mirror made of zinc selenium (ZnSe) with a reflectance of 65%. The 1000 μm light emitted from the laser gas molecules is amplified and a portion is outputted from the output mirror 5 as laser light 6 to the outside.

The laser gas, which has become hot due to laser oscillation, flows into the cooler 8a through the circulation passage 7 and is cooled. Blower 9
A Roots blower is used to push the laser gas to the right in the figure, and after the heat of compression by the blower 9 is removed by the cooler 8b, it enters the filter 10.

The filter 10 is made of glass fiber, polypropylene, cellulose acetate, etc., and has a multilayer structure in which a plurality of filters with different filtration precisions (for example, (00 μm and 10 μm1 or 100 μm and 10 μm and 1 μm) are stacked one on top of the other), and is used to filter oil mist in the laser gas. The laser gas filtered by the filter 10 flows into the discharge tube 1 again.

A bypass passage 13 is connected between the front and rear of the filter 10 in the circulation passage 7 via a valve 11 and a filter 12. However, this valve 11 is normally closed.

On the other hand, pressure sensors 21 and 22 are installed before and after the filter 10, respectively, to measure the gas pressure in the circulation passage 7 and output measured values P1 and P2. The computing unit 23 calculates a difference ΔPa by subtracting the measured value P2 from the measured value P1. The comparator 24 compares the difference △Pa with a preset value P.
When the difference ΔPa exceeds the set value Pr, an alarm signal Sa is generated. The display device 25 displays a message urging replacement of the filter 10 based on this alarm signal Sa.

Further, the calculator 26 calculates the difference by subtracting the set value Pr from the difference ΔPa, and calculates the difference (
If the value of ΔPa-Pr) is 0 or less, it is 0, and if it is positive, a signal proportional to that value is output as the valve opening signal ΔPb. The driver 27 amplifies the valve opening signal ΔPb and opens the valve 11.

FIG. 3 is a diagram showing the structure of the pressure sensor 21. The figure is a cross-sectional view, and the pressure introduction part 21a and the vacuum chamber 21b are separated by a silicon substrate 21c formed into a circular concave shape. The pressure p1 in the circulation passage 7 is the pressure inlet 21
When introduced through a, the silicon substrate 21c is distorted,
The resistance value of the silicon substrate 21c changes due to the piezoresistance effect, and a signal corresponding to this change is output. The pressure sensor 22 also has a similar structure.

FIG. 4 is a block diagram of a carbon dioxide laser oscillator according to another embodiment of the present invention. In the figure, the same numbers as in FIG. 1 have the same functions, and the explanation will be omitted. In this embodiment, a sub-circulation passage 14 that does not pass through the discharge tube 1 is provided in parallel with the circulation passage 7, and a filter 10, a filter 10
A bypass passage 13, pressure sensors 21 and 22, etc. are installed. As a result, the ventilation resistance of the circulation passage 7 is relatively low even under normal conditions, and the burden on the blower 9 is light.

In the above description, the timing for opening the valve 11 is synchronized with the generation of the alarm signal Sa, but these may be performed at independent timings. That is, the valve 11 may be gradually opened before the alarm occurs to control the gas flow rate in the discharge tube 1 to be always constant.

Further, although the opening degree of the valve 11 is made proportional to the difference between the two pressure sensors, this may be changed using another function in accordance with the characteristics of the filter inserted into the circulation passage 7.

Moreover, it is not necessary to provide a filter in particular in the bypass passage 13.

Furthermore, in addition to the semi-zero conductor strain gauge type used in this embodiment, a metal strain gauge type, a capacitance type, etc. can also be used as the pressure sensor.

〔Effect of the invention〕

As explained above, in the present invention, an alarm is displayed when the difference between the pressure sensors installed before and after the filter exceeds a set value, so if the filter is replaced according to this, the replacement time will not be too early. Economical.

In addition, since the bypass valve is opened little by little as the difference in the pressure sensor increases, even if the filter is not replaced immediately after an alarm occurs, the laser output will not decrease, making it reliable. Improves sex.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a carbon dioxide laser oscillator according to an embodiment of the present invention, Fig. 2 is a diagram showing changes in a valve opening signal according to an embodiment of the present invention, and Fig. 3 is an embodiment of the present invention. Fig. 4 is a structural diagram of a carbon dioxide laser oscillator according to another embodiment of the present invention. Discharge tube circulation passage Blower Filter valve Bypass passage Sub-circulation passage Pressure sensor Calculator Comparator Display device Driver alarm signal Valve open signal Fig. 2 Fig. 3

Claims (5)

[Claims] (1) In a gas laser oscillator in which a filter for removing impurities is provided in a laser gas circulation path, first and second pressure sensors that measure gas pressure at positions immediately before and after the filter in the circulation path; , monitoring means for outputting a predetermined alarm signal when the difference between the measured values of the first and second pressure sensors exceeds a set value; and displaying an alarm prompting replacement of the filter based on the alarm signal. A gas laser oscillator characterized by having: a display means for displaying the image; (2) In a gas laser oscillator in which a filter for removing impurities is provided in a laser gas circulation passage, a bypass passage connecting the front and back of the filter in the circulation passage, and a bypass passage provided in the bypass passage for circulation of the laser gas. a valve that shuts off the flow; first and second pressure sensors that measure gas pressure at positions immediately before and after the filter in the circulation passage; and a difference between the measured values of the first and second pressure sensors. A gas laser oscillator comprising: signal generating means that generates a predetermined valve opening signal when the valve opening signal exceeds a set value; and valve opening means that opens the valve at a predetermined opening degree in response to the valve opening signal. . (3) The gas laser oscillator according to claim 2, wherein the valve opening means is configured to open the valve at an opening degree corresponding to the difference. (4) The gas laser oscillator according to claim 2, wherein another filter for removing impurities in the laser gas is provided also in the bypass passage. (5) The gas laser oscillator according to claims 1 and 2, wherein the filter and the bypass passage are provided in a circulation passage that does not pass through a resonator.