JPH0448668A - Laser gas pressure control method - Google Patents

Abstract

PURPOSE:To enable laser gas pressure control which does not allow laser output to remain during switching of beam from 'on' to 'off' by providing a gas pressure control means when beam is switched 'off' which controls a gas pressure to an initial set pressure again when beam us switched 'off'. CONSTITUTION:A control device 4 outputs an output instruction value in accordance with an 'on' signal from a beam on/off switch 8, supplies a high frequency current to a discharge tube 31 through an output control circuit 9 and an excitation power supply 10, and adjusts opening of a laser gas control valve 2 by obtaining difference between a detection signal of a gas pressure sensor 7 and a set pressure. Control of a gas pressure is stopped when beam is switched 'on' and a gas pressure detected after a specified time passed is controlled as a set pressure; therefore, a gas pressure set pressure during beam 'on' is set low by a gas pressure inside an air blow system when beam is switched 'on'. Opening of the laser gas control valve 2 is held fixed and a gas pressure inside the discharge tube 31 is controlled high only by a pressure rise. As a result, a gas pressure inside the discharge tube 31 lowers rapidly when beam is switched from 'on' to 'off' and laser output does not remain.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laser gas pressure control method for a gas laser oscillator, and more particularly to a laser gas pressure control method in which no laser output remains when switching from a beam-on state to a beam-on state.

[Conventional technology]

The gas laser oscillator is controlled so that the laser gas pressure is always at a predetermined set pressure regardless of whether the beam is on or off.

This laser gas pressure (laser gas pressure inside the discharge tube) is controlled by controlling the opening degree of the laser gas control valve that opens into the ventilation system based on the deviation between the set pressure and the gas pressure in the ventilation system detected by the gas pressure sensor. It is done by controlling.

FIG. 6 is a diagram showing an operation time chart using a conventional laser gas pressure control method. In the figure, when the beam is turned on from the beam-off state, the gas temperature increases and the gas pressure increases within the discharge tube, while the gas flow rate increases and the gas pressure decreases within the blower system (between a and b). When the gas pressure sensor detects a decrease in the gas pressure in the blower system, the control device increases the opening degree of the laser gas control valve to increase the gas pressure in the blower system by the amount of the decrease, and adjusts it to a predetermined setting. Controlled by pressure. At this time, the gas pressure within the discharge tube further increases (between b and c). This high level of gas pressure is maintained within the discharge tube (between c and d).

[Problem to be solved by the invention]

However, when the beam is turned off in this state, the gas inside the discharge tube is rapidly cooled, contrary to when the beam is turned on from the beam off, and the gas pressure decreases within the discharge tube and increases within the ventilation system (between d and c). The control device closes the opening degree of the laser gas control valve (d- in (D)) in order to control the gas pressure in the blowing system detected by the gas pressure sensor to a predetermined set pressure.
between f).

The gas pressure inside the discharge tube, which has been maintained at a high level, decreases, but because the exhaust capacity of the ventilation system is limited, it takes time for the pressure to decrease (for example, several tens of seconds, between e and f). For this reason, there is a problem in that the laser output remains for a while even after the beam is turned off.

The present invention has been made in view of these points, and it is an object of the present invention to provide a laser gas pressure control method in which no laser output remains when switching from beam on to beam off.

[A means of promise to solve problems]

In order to solve the above problems, the present invention provides a gas pressure sensor in the blowing system that circulates gas in the discharge tube of a gas laser oscillator, and controls the gas pressure based on the gas pressure detected by the gas pressure sensor. In the control method, a beam-off state gas pressure control means controls the gas pressure to an initial setting pressure when the beam is off, and a beam-off state gas pressure control means stops controlling the gas pressure when the beam is switched on, and after a predetermined time elapses, the gas pressure is detected by the gas pressure sensor. A beam-on gas pressure control means for controlling the gas pressure by setting the gas pressure to a set pressure, and a beam-off switch gas pressure control means for controlling the gas pressure to the initial setting pressure again when the beam is switched off. A laser gas pressure control method is provided.

Further, in a laser gas pressure control method in which a gas pressure sensor is provided in a blowing system that circulates gas in a discharge tube of a gas laser oscillator, and the gas pressure is controlled based on the gas pressure detected by the gas pressure sensor, when the beam is off, the gas is a beam-off state gas pressure control means for controlling the pressure to an initial setting pressure; and a gas pressure control means for stopping the control of the gas pressure when the beam is switched on, and controlling the amount of change per unit time of the gas pressure detected by the gas pressure sensor to a predetermined value. beam-on gas pressure control means for controlling the gas pressure by setting the gas pressure to a set pressure when the gas pressure becomes below; and beam-off switching gas pressure control means for controlling the gas pressure to the initial setting pressure again when switching to beam off. Provided is a laser gas pressure control method characterized by having the following.

Furthermore, in a laser gas pressure control method in which a gas pressure sensor is provided in a blowing system that circulates gas in a discharge tube of a gas laser oscillator, and the gas pressure is controlled based on the gas pressure detected by the gas pressure sensor, when the beam is off, the gas is A beam-off state gas pressure control means for controlling the pressure to an initial setting pressure, and a beam-on means for calculating the gas pressure corresponding to the laser output command value when switching the beam on, and controlling the gas pressure using the calculated gas pressure as the set pressure. Provided is a laser gas pressure control system characterized by comprising: gas pressure control means at the time of beam off switching; and gas pressure control means at beam off switching for controlling the gas pressure to the initial setting pressure again at the time of beam off switching.

[Effect]

In claim 1 of the present invention, control of the gas pressure is stopped when the beam is switched on, and after a predetermined period of time has elapsed, the gas pressure is controlled using the gas pressure detected by the gas pressure sensor as the set pressure.

In addition, in claim 2 of the present invention, the control of the gas pressure is stopped when the beam is switched on, and the gas pressure is controlled when the amount of change per unit time in the gas pressure detected by the gas pressure sensor becomes equal to or less than a predetermined value. Control gas pressure as set pressure.

Therefore, the set pressure is set lower by the gas pressure within the blower system that decreases as the gas temperature increases when the beam is switched on. Therefore, the opening degree of the laser gas control valve does not change and is held constant, and the gas pressure inside the discharge tube is only controlled to be high by the pressure increase that occurs as the gas temperature rises, and does not reach a high level. . As a result, when switching from beam on to beam off, the gas pressure within the discharge tube quickly decreases and no laser output remains.

Furthermore, in claim 3 of the present invention, a gas pressure corresponding to a laser output command value is calculated at the time of beam-on switching, and the gas pressure is controlled using the calculated gas pressure as a set pressure. In this way, the set pressure is not affected by gas pressure fluctuations that occur due to the rise in gas temperature when switching on the beam, and is controlled to an appropriate pressure corresponding to the laser occupation command value. Ru. Therefore, when switching from beam on to beam off, the gas pressure within the discharge tube quickly decreases and no laser output remains.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing the overall configuration of a basic gas laser oscillator embodying the present invention. It looks like the picture, 1~2k
Laser gas is supplied from a gas cylinder 1 with a pressure of gf/cm 2 and introduced into a chamber 3 via a laser gas control valve 2 . The opening degree of the laser gas control valve 2 is controlled by a control device 4.

The chamber 3 consists of a discharge tube 31 and a ventilation system 32. The ventilation system 32 includes a blower 33 and cooling heat exchangers 34a and 34.
It is composed of b. Blower 33 circulates the laser gas within discharge tube 31 through heat exchangers 34a and 34b. The heat exchanger 34a is a heat exchanger that cools the gas that has become hot due to laser oscillation in the discharge tube 31, and the heat exchanger 34b is a heat exchanger that removes the compression heat generated by the blower 33.

An exhaust pump 6 is connected to the chamber 3 via an exhaust valve 5.
is connected, and this causes, for example, 30
It is evacuated to a pressure of Torr, and gas that deteriorates due to discharge is constantly evacuated and replaced during operation. In addition,
The exhaust valve 5 has an absolute flow rate of gas of 1 by manual VJ simulation.
It is set to be ±0.2β/min.

The gas pressure sensor 7 is of a capacitance manometer type and is provided near the heat exchanger 34a on the intake side of the blower 33 to detect the gas pressure within the blowing system 32 and input it to the control device 4.

The beam on/off switch 8 inputs its on/off signal to the control device 4 .

The control device 4 applies an output command value in response to the ON signal from the beam on/off switch 8 and supplies high frequency current to the discharge tube 31 via the output control circuit 9 and the excitation power source 10. Furthermore, the control device 4, as will be described in detail later,
The deviation between the detection signal of the gas pressure sensor 7 and the set pressure is determined, and the opening degree of the laser gas control valve 2 is adjusted based on this deviation. Thereby, the gas pressure within the chamber 3 is maintained at the set pressure.

FIG. 2 is a flowchart showing an embodiment of the laser gas pressure control method of the present invention. In the figure, the number following S indicates the step number.

[S1] Normal gas pressure control during beam-off is performed, and the gas pressure is controlled to the initial set pressure.

[S2] It is determined whether or not the beam on/off switch 8 is turned on. If it is turned on, the process proceeds to S3.

[S3] Stop gas pressure control.

[S4] The timer is activated, and the
5) is counted.

[S5] After a predetermined time has elapsed, the gas pressure detected by the gas pressure sensor 7 is read and an average value is calculated.

[S6] The read gas pressure (average value) is set as the gas pressure setting pressure.

Gas pressure control is restarted at the gas pressure setting pressure of C571 [56].

[S8] It is determined whether the beam on/off switch 8 has been turned off, and if it has been turned off, the process advances to S9.

[S9] Set the initial setting pressure to the gas pressure setting pressure, and proceed to Sl.

As described above, in this embodiment, control of the gas pressure is stopped when the beam is switched on, and after a predetermined period of time, the gas pressure detected by the gas pressure sensor 7 is used as the gas set pressure to control the gas pressure.

Therefore, the gas pressure set pressure when the beam is on is set lower by the amount of the gas pressure within the blowing system that decreases as the gas temperature increases when the beam is switched on. Therefore, the opening degree of the laser gas control valve 2 is kept constant without changing (see Fig.
D)) The gas pressure inside the discharge tube 31 is only controlled to be high by the pressure increase caused by the rise in gas temperature, and does not reach a high level (between a and d in the figure). As a result, when switching from beam on to beam off, the discharge tube 3
The gas pressure inside 1 quickly decreases, and no laser output remains (between d and e in the figure).

In the above explanation, the gas pressure control is stopped and the gas pressure is read after a predetermined period of time to set the gas pressure set pressure. It is also possible to detect the gas pressure and read the gas pressure when the amount of change in the gas pressure per unit time becomes equal to or less than a predetermined value (point b in the figure) and set it as the gas pressure setting pressure.

FIG. 3 is a flowchart showing another embodiment of the laser gas pressure control method of the present invention.

[S11] Normal gas pressure control during beam-off is performed.

[S12] It is determined whether or not the beam on/off switch 8 is turned on. If it is turned on, the process proceeds to S13.

C313] The gas pressure corresponding to the laser output command value is calculated. The gas pressure corresponding to this laser output command value is
Gas pressure at maximum laser output command value (e.g. 1kW) (
For example, 50Torr) and gas pressure at beam off (
It is determined by proportional distribution from the initial setting pressure (for example, 60 Torr) (Fig. 4).

C314] Using the calculated value of 313 as the gas pressure setting pressure, the gas pressure is controlled when the beam is on.

[315] Determine whether or not the beam on/off switch 8 has been turned off. If it has been turned off, proceed to S16.

[S16] The initial set pressure is set as the gas pressure set pressure, and the process proceeds to S11.

In this manner, in this embodiment, the gas pressure corresponding to the laser output command value is calculated at the time of beam-on switching, and the gas pressure is controlled using the calculated gas pressure as the gas pressure set pressure. With this guarantee, the gas pressure set pressure is not affected by gas pressure fluctuations that occur due to the rise in gas temperature when switching on the beam, and the gas pressure inside the discharge tube 31 is maintained at an appropriate pressure corresponding to the laser output command value. (Figure 5, between a and d). Therefore, the opening degree of the laser gas control valve 2 is kept constant without changing (see (D) in the figure), and the same effect as in the first embodiment is achieved.

〔Effect of the invention〕

As explained above, in the present invention, the set pressure of the gas pressure is appropriately switched when switching from beam off to beam on, so that the gas pressure inside the discharge tube when the beam is on is properly controlled and does not reach a high level. Therefore, when switching from beam on to beam off, the gas pressure within the discharge tube quickly decreases and no laser output remains.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of a gas laser oscillator according to the present invention, FIG. 2 is a flowchart showing an embodiment of the laser gas pressure control method of the present invention, and FIG. 3 is a flow chart showing the laser gas pressure control method of the present invention. A flowchart showing another embodiment of the control method, FIG. 4 is a diagram showing the relationship between the laser output command value and the gas pressure setting pressure, and FIG. 5 is a diagram showing the operation time chart according to the laser gas pressure control method of the present invention. FIG. 6 is a diagram showing an operation time chart using a conventional laser gas pressure control method. Gas cylinder Laser gas control valve Controller Gas pressure sensor Beam on/off switch Discharge tube Blower system Figure 2 Figure 3 Figure 4

Claims (6)

[Claims] (1) In a laser gas pressure control method in which a gas pressure sensor is provided in a blowing system that circulates gas in a discharge tube of a gas laser oscillator, and the gas pressure is controlled based on the gas pressure detected by the gas pressure sensor, when the beam is off, the a beam-off state gas pressure control means for controlling the gas pressure to an initial setting pressure; and a beam-off state gas pressure control means for stopping the control of the gas pressure when the beam is switched on, and controlling the gas pressure detected by the gas pressure sensor after a predetermined period of time to be the set pressure. A laser gas pressure control method comprising: a beam-on gas pressure control means for controlling the pressure; and a beam-off switch gas pressure control means for controlling the gas pressure to the initial setting pressure again when the beam is switched off. (2) In a laser gas pressure control method in which a gas pressure sensor is provided in a blowing system that circulates gas in a discharge tube of a gas laser oscillator, and the gas pressure is controlled based on the gas pressure detected by the gas pressure sensor, when the beam is off, a beam-off state gas pressure control means for controlling the gas pressure to an initial setting pressure; and a gas pressure control means for stopping the control of the gas pressure when the beam is switched on, and controlling the amount of change per unit time of the gas pressure detected by the gas pressure sensor to a predetermined amount. beam-on gas pressure control means for controlling the gas pressure by setting the gas pressure at a value below the set pressure; and beam-off switching gas pressure control means for controlling the gas pressure to the initial setting pressure again when switching to beam off. A laser gas pressure control method comprising: (3) In a laser gas pressure control method in which a gas pressure sensor is provided in a blowing system that circulates gas in a discharge tube of a gas laser oscillator, and the gas pressure is controlled based on the gas pressure detected by the gas pressure sensor, when the beam is off, A beam-off state gas pressure control means for controlling gas pressure to an initial setting pressure, and calculating a gas pressure corresponding to a laser output command value at the time of beam-on switching, and controlling the gas pressure using the calculated gas pressure as a setting pressure. A laser gas pressure control method comprising: a beam-on gas pressure control means; and a beam-off switch gas pressure control means for controlling the gas pressure to the initial setting pressure again when the beam is switched off. (4) The laser gas pressure control method according to claim 1, 2 or 3, wherein the gas pressure is controlled by the opening degree of a laser gas control valve that opens into the ventilation system. (5) The laser gas pressure control method according to claim 1, 2 or 3, wherein the gas pressure sensor is provided on the intake side of a blower of the ventilation system. (6) The gas pressure corresponding to the laser output command value is a value calculated by proportionally distributing the gas pressure at the maximum laser output command value and the gas pressure at the minimum laser output command value. The laser gas pressure control method according to claim 3.