JPH0738180A - Gas circulating laser equipment - Google Patents

Abstract

PURPOSE:To eliminate pressure fluctuation which is generated when root blower and gas laser medium flow in a gas circulating system and reduce the fluctuation of laser beam power by generating the same amplitude and reverse phase pressure fluctuation by oscillating an oscillator. CONSTITUTION:Gas laser medium is compressed by root blower 3 to be pushed into a cooler 4, and pressure fluctuation is generated. An oscillator 17 inputs an amplifying signal S4, and generates the pressure fluctuation of the same amplitude and reverse phase compared with the pressure fluctuation detected by a first pressure sensor 12. A second pressure sensor 18 arranged on the downstream side of the oscillator 17 detects the pressure fluctuation in a gas laser medium tube and inputs a second detecting signal S5 to an adjuster 15. The amplifying signal S4 corresponding to the first detecting signal S1 and the second detecting signal S5 detected by the first pressure sensor 12 and the second pressure sensor 18 is inputted to the oscillator 17 and the oscillator 17 is oscillated. Thus, the gas laser medium which allows no pressure fluctuation is carried to a laser resonator 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas circulation type laser device in which the pressure fluctuation of a gas laser medium is reduced in order to improve the processing performance of a laser processing machine.

[0002]

2. Description of the Related Art (Description of FIGS. 1 and 2) FIG. 1 is a diagram showing the structure of a conventional high-speed axial-flow CO2 laser device which is a gas circulation laser device. In the figure, reference numeral 1 denotes a laser resonator, which excites a gas laser medium by discharge excitation by a high voltage power source 2 and causes laser resonance to output a laser beam 19. A roots blower 3 sends the gas laser medium to the laser resonator 1 via the gas cooler 4 and the gas supply duct 6 provided on the discharge side. Then, the gas laser medium is returned from the laser resonator 1 to the roots blower 3 via the gas exhaust duct 7 and the gas cooler 5 provided on the suction side of the roots blower 3. Reference numeral 11 denotes a gas circulation system, which includes a roots blower 3, a gas cooler 4, a gas supply duct 6, a gas exhaust duct 7 and a gas cooler 5. The discharge voltage fluctuates due to pressure fluctuations caused by the rotation of the roots blower 3 and pressure fluctuations (hereinafter referred to as pressure fluctuations) generated when the gas laser medium flows through the gas circulation system 11. As a result, the power of pumping changes and the output of the laser light 19 fluctuates. If the output of the laser light 19 fluctuates, there is a problem that the cut surface becomes rough during laser processing.

For this reason, in the prior art, as a means for improving the pressure fluctuation, a side hole 8 is provided in the gas supply duct 6 on the discharge side of the roots blower 3 for connection, as disclosed in JP-A-2-285686. A method utilizing the Helmholtz resonance phenomenon, such as connecting the resonance container 10 using the duct 9, is adopted.

FIGS. 2A and 2B show the pressure P [Tor of the gas laser medium in the gas supply duct 6 shown in FIG.
2] FIG. 2 is a diagram showing an example of the time course t of [r].
(A) shows the case where the Helmholtz resonance phenomenon is not used, and (B) shows the case where the Helmholtz resonance phenomenon is used. In FIGS. 9A and 9B, the average pressure Pa is 60 [Torr] and the cycle is 240 [H].
z]. When the Helmholtz resonance phenomenon shown in FIG. 7B is used, the pressure fluctuation is considerably improved as compared with FIG.

[0010]

The pressure fluctuation occurring when the gas laser medium flows through the gas circulation system 11 is not constant in frequency or amplitude. However, since the means for removing the pressure fluctuation utilizing the resonance phenomenon is effective only at the resonance frequency or the frequency which is an integral multiple thereof, it causes the fluctuation of the output of the laser light 19 as shown in FIG. 2B. There was a problem that the pressure fluctuation could not be sufficiently reduced.

An object of the present invention is to eliminate pressure fluctuations, reduce output fluctuations of laser light 19, and improve laser processing quality.

[0020]

According to the present invention, as shown in FIG. 3, a laser resonator 1 for discharging a laser beam 19 from the gas laser medium by laser resonance and exciting the gas laser medium by discharge, and a laser resonator for the gas laser medium. In a gas circulation type laser device comprising a gas circulation system 11 which circulates 1 to 1, a first pressure sensor 12 which detects a pressure fluctuation of a gas laser medium and outputs a first detection signal S1, and a first detection signal S1. The feedback control unit 13 that inverts the phase and outputs the first inversion signal S2, and the first inversion signal S
Waveform generator 14 for inputting 2 and generating waveform signal S3
And a vibrator 17 positioned downstream of the first pressure sensor 12 for inputting the waveform signal S3 to generate a pressure fluctuation in the gas laser medium, and a gas laser positioned downstream of the vibrator 17 A second pressure sensor 18 which detects a pressure fluctuation of the medium and outputs a second detection signal S5; and a regulator 15 which adjusts the second detection signal S5 and inputs an adjustment signal S6 to the feedback control unit 13. It is a gas circulation type laser device equipped with.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Explanation of FIGS. 3 to 6) FIG. 3 is a diagram showing an embodiment of the configuration of the gas circulation laser apparatus of the present invention. In the figure, the same reference numerals as those in FIG. 1 are the same as those in the description of FIG. In FIG. 3, reference numeral 12 denotes a first pressure sensor, which is a gas supply duct 6
And detects a pressure fluctuation in the gas laser medium and outputs a first detection signal S1. 13 is a feedback control unit, which inverts the phase of the first detection signal S1,
The first inverted signal S2 is input to the waveform generator 14. The waveform generator 14 performs frequency analysis on the first inverted signal S2 by FFT (Fast Fourier Transform), and inputs the waveform signal S3 to the amplifier 16. The amplifier 16 amplifies the waveform signal S3 and inputs the amplified signal S4 to the vibrator 17.

In FIG. 3, the gas laser medium is compressed by the roots blower 3 and pushed out to the cooler 4, so that pressure fluctuations occur. FIG. 4A is a diagram showing the time lapse t of the pressure P [Torr], and the average pressure Pa and the cycle are the same as those in FIG. Figure 4 (B)
The waveform generator 14 inputs the first inverted signal S2 and F
Frequency F [Hz] (horizontal axis) and pressure intensity level [d when a period number analysis is performed by FT (Fast Fourier Transform)
It is a figure which shows the relationship with B] (vertical axis). The oscillator 17 is
Since the amplified signal S4 is input and a pressure fluctuation having the same amplitude and opposite phase as the pressure fluctuation detected by the first pressure sensor 12 is generated, the pressure fluctuation in the gas laser medium is canceled.

However, the characteristics of the vibrator 17 and the vibrator 17
Pressure fluctuation produced by the first pressure sensor 12
Since there is variation in the coupling state with the pressure fluctuation detected by, the pressure fluctuation cannot be canceled out to a sufficiently low level. Therefore, as shown in FIG. 3, the second pressure sensor 18 is arranged on the downstream side of the vibrator 17. The second pressure sensor 18 detects a pressure fluctuation in the gas laser medium,
The second detection signal S5 is input to the adjuster 15. Adjuster 1
5, frequency detection analysis of the detection signal S5 by FFT,
The adjustment signal S6 is input to the feedback control unit 13. The feedback control unit 13 controls the adjustment signal S
6 is phase-inverted and a second inversion signal S7 is output. Second
The inverted signal S7 of is added to the first inverted signal S2 and is input to the waveform generator 14. The waveform generator 14 generates a waveform signal S3 corresponding to the first inverted signal S2 and the second inverted signal S7.
Is input to the amplifier 16. The amplifier 16 outputs the amplified signal S4
Is input to the vibrator 17.

FIG. 5A is a diagram showing the time lapse t of the pressure P [Torr] detected by the second pressure sensor 18. The average pressure Pa and the cycle are the same as those in FIG. First
The pressure sensor 12 vibrates the oscillator 17 to cancel the pressure fluctuation in the gas laser medium, and as a result, it is shown that the pressure fluctuation is not canceled to a sufficiently low level. FIG. 5B shows the frequency F [Hz] (horizontal axis) and the pressure intensity level L [dB] (vertical axis) when the regulator 15 inputs the second detection signal S5 and performs frequency analysis by FFT. ) Is a diagram showing a relationship with FIG. A first detection signal S1 detected by the first pressure sensor 12 and the second pressure sensor 18.
By inputting the amplified signal S4 corresponding to the first detection signal S5 and the second detection signal S5 to the vibrator 17 to vibrate the vibrator 17, as shown in the time passage t of the pressure P [Torr] in FIG. In addition, a gas laser medium with almost no pressure fluctuation is sent to the laser resonator 1. In FIG. 3A, the average pressure Pa and the cycle are the same as in FIG. Figure 6
(B) is an FFT analysis of this pressure fluctuation, which shows the frequency F [Hz] (horizontal axis) and the pressure intensity level L [d.
It is a figure which shows the relationship with B] (vertical axis).

[0040]

According to the gas circulation type laser device of the present invention, the first pressure sensor 12 detects the pressure fluctuation generated due to the rotation of the roots blower 3 and the pressure fluctuation generated when the gas laser medium flows through the gas circulation system 11. And the second pressure sensor 18
The pressure fluctuation is canceled by the vibration of the laser resonator 1 before propagating to the laser resonator 1. This has the effect of significantly reducing the output fluctuation of the output laser light 19 and improving the quality of laser processing.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a conventional gas circulation type laser device.

FIG. 2 is a diagram showing the time course t of the pressure P of the gas laser medium.

FIG. 3 is a diagram showing an embodiment of a configuration of a gas circulation laser device of the present invention.

FIG. 4 is a diagram showing the relationship between the time lapse t of the pressure P, the frequency F, and the pressure intensity level L.

FIG. 5 is a diagram showing the relationship between the time elapse t of the pressure P, the frequency F, and the pressure intensity level L.

FIG. 6 is a diagram showing the relationship between the time elapsed t of the pressure P, the frequency F, and the pressure intensity level L.

[Explanation of symbols]

 1 Laser Resonator 2 High Voltage Power Supply 3 Roots Blower 4,5 Gas Cooler 6 Gas Supply Duct 7 Gas Exhaust Duct 8 Side Hole 9 Connection Duct 10 Resonance Vessel 11 Gas Circulation System 12 First Pressure Sensor 13 Feedback Control Unit 14 Waveform Generation Device 15 Adjuster 16 Amplifier 17 Transducer 18 Second pressure sensor 19 Laser light S1 First detection signal S2 First inversion signal S3 Waveform signal S4 Amplification signal S5 Second detection signal S6 Adjustment signal S7 Second inversion signal

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location 7454-4M H01S 3/097

Claims (1)

[Claims] 1. A gas circulation laser device comprising a laser resonator for exciting a gas laser medium by discharge and extracting laser light from the gas laser medium by laser resonance, and a gas circulation system for circulating the gas laser medium to the laser resonator. A first pressure sensor that detects a pressure fluctuation of the gas laser medium and outputs a first detection signal; a feedback control unit that phase-inverts the first detection signal and outputs a first inversion signal; A waveform generator that inputs a first inverted signal to generate a waveform signal, and a vibration that is located downstream of the first pressure sensor and that receives the waveform signal to generate a pressure fluctuation in the gas laser medium. A second pressure sensor that is located downstream of the oscillator and that detects a pressure fluctuation of the gas laser medium and outputs a second detection signal; And a regulator for adjusting the detection signal of the above and inputting the adjustment signal to the feedback control unit.