JPH05259553A - Lasing apparatus - Google Patents

Abstract

PURPOSE:To prevent discharge ignition failure at a repetion frequency lower than or equal to a specified value, at the time of pulse operation of low output and low duty. CONSTITUTION:A cavity resonator 21 for generating pre-discharge is arranged in the upper stream side of laser medium gas flow from an electrode 8 arranged in a discharge tube 7, so as to be set at a position deviated from the optical axis of a laser resonator. A cavity waveguide 22 is connected with the cavity resonator 21, and a magnetron 23 is connected with the cavity waveguide 22 via a stub tuner 24. Microwave power generated by the magnetron 24 is transmitted to the inside of the discharge tube 7, thereby causing pre-discharge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial laser oscillating device for cutting, welding, heat treating metal or the like by utilizing a generated laser beam.

[0002]

2. Description of the Related Art A conventional laser oscillator will be described below with reference to the drawings. FIG. 3 is a configuration diagram of a conventional high-speed axial flow type laser oscillator. In FIG. 3, the output mirror 2 is provided at one end of the output mirror holder 1, and the main flange 3a is provided at the other end. A terminal mirror 5 is provided at one end of the terminal mirror holder 4, and a main flange 3b is provided at the other end. A discharge tube 7 is provided between each of the main flanges 3a and 3b and the assembly block 6, and an electrode 8 is provided so as to sandwich the discharge tube 7.
Are provided respectively. Further, one of the electrodes 8 is grounded, the other is a copper plate 9, a matching circuit 10 and a coaxial cable.
It is connected to the RF power source 12 via 11. This RF power supply
Impedance matching is important for injecting electric power from 12 into the discharge tube 7. Since the RF power source 12 is generally output with an output impedance of 50 ohms, a coaxial cable 11 having an impedance of 50 ohms, etc., near the laser resonator. It is connected to the matching circuit 10 installed in. Furthermore, the matching circuit 10 is connected in parallel to the electrode 8 provided for each discharge tube 7 by a copper plate 9 or the like, and the matching circuit 10 converts the impedance into the impedance of the discharge tube 7 side, and RF power is low loss and RF.
It is transmitted from the power supply 12 to the discharge tube 7.

Further, one end of the blower 13 and the main flanges 3a, 3b, and the other end of the blower 13 and the assembly block 6 are connected by a pipe 15 via a heat exchanger 14. .. A vacuum container is constituted by the main flanges 3a and 3b, the collecting block 6, the discharge tube 7 and the pipe 15 described above, and the laser medium gas is filled in the vacuum container. A heat exchanger 14 is provided in the middle of the pipe 15 for the purpose of cooling the laser medium gas.

The operation of the above arrangement will be described below. First, the vacuum chamber is filled with the laser medium gas and kept at a constant pressure, and at the same time, the blower 13 circulates the laser medium gas in the vacuum chamber. The output from the RF power source 12 is fed to the laser medium gas in the circulated discharge tube 7 by the coaxial cable 1
1, the matching circuit 10, the copper plate 9, and the electrode 8 provided outside the discharge tube 7 are injected to discharge the laser medium gas to generate laser light. The generated laser light is amplified by the optical resonator composed of the output mirror 2, the terminal mirror 5 and the discharge tube 7, and a part of the laser light is taken out from the output mirror 2 and used for processing.

At this time, the heat exchanger 14 cools the laser medium gas by removing the heat generated in the discharge tube 7 and the heat generated when the laser medium gas is compressed by the blower 13. Further, in order to configure the optical resonator, the output mirror 2 and the terminal mirror 5 need to be maintained in parallel. However, the output mirror holder 1 and the terminal mirror holder 4 are used for fine adjustment, and the output mirror 2
Keep the end mirror 5 parallel. Therefore, the main flange 3
The a, 3b and the assembly block 4 are structurally rigidly configured and have sufficient strength so that the angle of the mirror does not change due to thermal expansion or external force.

[0006]

However, in the above-mentioned conventional configuration, when the RF power source 12 is actually connected to the laser oscillator through the matching circuit 10, the pulse is turned on and the pulse OF is turned on.
Since the impedance of the discharge tube 7 at F is extremely different, sufficient electric power cannot be transmitted to the discharge tube 7 and a sufficient electric field is not applied to start the discharge particularly during pulse operation with low output and low duty. There was a problem that a discharge ignition mistake occurred.

The present invention solves the above-mentioned conventional problems. Since the impedance of the discharge tube at the time of pulse ON is extremely different from that at the time of pulse OFF, even at the time of pulse operation with a low output and a low duty, the frequency is kept below a certain repetition frequency. It is an object of the present invention to provide a laser oscillating device capable of preventing the discharge ignition mistake.

[0008]

In order to solve the above problems, a laser oscillator of the present invention circulates a laser medium gas through a laser resonator having a plurality of discharge tubes and mirrors provided at both ends thereof, A laser oscillating device for transmitting high-frequency power to the laser medium gas via electrodes respectively arranged outside the plurality of discharge tubes to discharge the laser medium gas in the discharge tubes to generate laser light. hand,
Cavity resonance means provided in the upstream portion of the flow of the laser medium gas from the electrode portion outside the discharge tube to generate preliminary discharge,
A cavity waveguide for transmitting microwave power to the cavity resonating means and a magnetron for generating the microwave power are provided.

The cavity resonance means of the laser oscillator of the present invention is provided at a position off the optical axis of the laser resonator.

[0010]

With the above structure, since there is a pre-discharge area in the upstream portion of the laser medium gas of the discharge tube, plasma partially ionized by the flow of the laser medium gas flows into the discharge tube, and the impedance change in the discharge tube is reduced, which reduces the Even during pulse operation with low output duty, discharge ignition is stabilized, the controllable range of pulses is expanded, and discharge ignition mistakes below a certain repetition frequency as in the past are prevented. Also,
Microwaves have a strong directivity and can concentrate power in the pre-discharge region to generate electric power and generate a stabilized plasma. No cooling is required, and the structure is simple and a magnetron can be used as a power source, and an inexpensive preliminary discharge device can be obtained. Further, since the priming discharge region is arranged at a position not existing on the optical axis of the laser resonator in the upstream part of the flow of the laser medium gas from the electrode, there is no fear that unnecessary laser light is erroneously output when the pulse is turned off. It is possible to obtain a safe and highly reliable pre-discharge device that does not damage the work when the laser processing is idle.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. It should be noted that the same effects as those of the conventional example are given the same reference numerals and the description thereof will be omitted.

FIG. 1 is a block diagram of a high-speed axial flow type laser oscillating device showing an embodiment of the present invention. In FIG. 1, a cavity resonator 21 for generating a preliminary discharge includes a plurality of discharge tubes 7 and an output mirror 2 and a terminal mirror 5 as mirrors provided at both ends thereof.
Is installed at a position deviated from the optical axis of the laser resonator having, that is, the cavity resonator 21 does not exist on the optical axis of the laser resonator. The cavity resonator 21 is installed outside the discharge tube 7 and upstream of the flow of the laser medium gas from the electrode 8 arranged substantially parallel to the discharge tube 7, that is, the flow of the laser medium gas near the discharge tube 7. It is installed on the upstream side of where the preliminary discharge is generated. Further, the cavity resonator 21 includes a cavity waveguide 22 that transmits microwave power, and a stub tuner 24 that is provided in the cavity waveguide 22 and that matches the impedance of the discharge tube 7 and the output impedance of the magnetron 23. It is connected to a magnetron 23 via the magnetron 23 and transmits the microwave power generated by the magnetron 23 to the discharge area in the cavity 21. Further, the magnetron 23 is continuously operated at the same time as the preparation for laser oscillation is completed, so that the high voltage power source of the magnetron 23 is inexpensively constructed.

The operation of the above arrangement will be described below. First, the microwave power required for preliminary discharge is generated by the magnetron 23, impedance-converted by the stub tuner 24, and then transmitted to the cavity resonator 21 through the cavity waveguide 22. The cavity resonator 21 is geometrically designed to have standing waves, and the electric field in the central portion of the cavity resonator 21 becomes high, so that discharge is started. On the other hand, the electric field in the vicinity of the wall forming the cavity resonator 21 is zero, so that the wall is not heated and no special cooling is required. The start of discharge is set so that the laser medium gas is stabilized at a predetermined pressure and is continuously output when the laser oscillation preparation is completed.

Further, by removing the preliminary discharge area from the optical axis of the laser resonator, damage to the work during idling is prevented.
When the preliminary discharge means designed in this way is provided, the discharge tube 7 always keeps a weakly ionized state, but laser oscillation does not occur due to its low density. However, when the discharge area is provided on the optical axis of the laser resonator, the ionization density of the discharge portion becomes a density sufficient for laser oscillation, so weak laser light is output and the work is damaged. In this way, the pulse controllable range is expanded by constantly flowing ionized plasma into the discharge tube 7 to the extent that laser oscillation does not occur, and a remarkable difference appears especially in the low output and low duty region.

Therefore, since there is a preliminary discharge area on the upstream side of the laser medium gas of the discharge tube 7, plasma partially ionized by the flow of the laser medium gas flows into the discharge tube 7 and the impedance change in the discharge tube 7 is reduced. , The ignition of the discharge is stabilized. As a result, the controllable range of the pulse is also expanded. This state is shown in FIG. As is clear from FIG. 2, it is possible to obtain stabilized pulse characteristics during pulse operation with low output and low duty, unlike the conventional one. In addition, microwaves have a strong directivity and can concentrate power in the priming discharge area to supply electric power to generate stabilized plasma.
22 and the stub tuner 24 determined by the geometric design of the cavity resonator 21 by optimizing the geometric design of the cavity resonator
No cooling of 21 is required, the structure is simple, and the magnetron 23 can be used as a power source, so that an inexpensive preliminary discharge device can be obtained. Further, the pre-discharge region is located upstream of the flow of the laser medium gas from the electrode 8 and the discharge tubes 7 and the output mirror 2 and the terminal mirror 5 as mirrors provided at both ends thereof.
By arranging the laser resonator at a position that does not exist on the optical axis of the laser resonator, there is no fear of unnecessary laser light being output accidentally when the pulse is turned off, and it is safe and scratches the workpiece during laser processing idle running. It is possible to obtain a highly reliable preliminary discharge device.

[0016]

As described above, according to the present invention, the preliminary discharge region is provided at the position upstream of the flow of the laser medium gas from the electrode and off the optical axis of the laser resonating means. Even during low-power low-duty pulse operation, discharge ignition is stabilized, the pulse controllable range can be significantly expanded, and it is possible to prevent discharge ignition mistakes at a certain repetition frequency or lower as in the past. Also,
It is possible to obtain a safe preliminary discharge device that is safe and does not damage the work during laser processing idle running without fear of erroneously outputting unnecessary laser light when the pulse is turned off.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a high-speed axial flow type laser oscillation device showing an embodiment of the present invention.

FIG. 2 is a diagram showing a region that can be controlled using the laser oscillator of FIG.

FIG. 3 is a configuration diagram of a conventional high-speed axial flow type laser oscillation device.

[Explanation of symbols]

 2 Output mirrors 3a, 3b Main flange 5 End mirror 7 Discharge tube 8 Electrode 10 Matching circuit 12 RF power supply 13 Blower 15 Piping 21 Cavity resonator 22 Cavity waveguide 23 Magnetron 24 Stub tuner

Claims (2)

[Claims] 1. A laser medium gas is circulated in a laser resonator having a plurality of discharge tubes and mirrors provided at both ends of the discharge tubes, and the laser is supplied via electrodes respectively arranged outside the plurality of discharge tubes. A laser oscillating device for transmitting high-frequency power to a medium gas to discharge the laser medium gas in the discharge tube to generate laser light, wherein the laser medium gas is provided upstream of an electrode portion outside the discharge tube. A laser oscillating device comprising: a cavity resonance unit that generates a preliminary discharge, a cavity waveguide that transmits microwave power to the cavity resonance unit, and a magnetron that generates the microwave power. 2. The laser oscillator according to claim 1, wherein the cavity resonator is provided at a position off the optical axis of the laser resonator.