KIEE International Transactions on Electrophysics and Applications

The Korean Institute of Electrical Engineers (대한전기학회)
권호 표지

Optimal Characteristics of a Long-pulse $CO_2$Laser by Controlling SCR Firing Angle in AC Power Line

  • Noh, Ki-Kyung (Dept. of Electrical Engineering, Pusan University) ;
  • Kim, Geun-Yong (Dept. of Electrical Engineering, Pusan University) ;
  • Chung, Hyun-Ju (Dept. of Electrical Engineering, Pusan University) ;
  • Min, Byoung-Dae (Dept. of Electrical Engineering, Pusan University) ;
  • Song, Keun-Ju (Dept. of Electrical Engineering, Pusan University) ;
  • Kim, Hee-Je (Dept. of Electrical Engineering, Pusan University)
  • Published : 2002.06.01
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Abstract

We demonstrate a simple pulsed $CO_2$ laser with millisecond long pulse duration in a tube at a low pressure of less than 30 Torr. The novel power supply for our laser system switches the voltage of the AC power line (60Hz) directly. The power supply doesn't need elements such as a rectifier bridge, energy-storage capacitors, or a current-limiting resistor in the discharge circuit. To control the laser output power, the pulse repetition rate is adjusted up to 60Hz and the firing angle of SCR(Silicon Controlled Rectifier) gate is varied from 30。 to 150。. A ZCS (Zero Crossing Switch) circuit and a PIC one-chip microprocessor are used to control precisely the gate signal of the SCR. The maximum laser output of 35 W is obtained at a total pressure of 18 Torr, a pulse repetition rate of 60 Hz, and a SCR gate firing angle of 90。 . In addition, the resulting laser pulse width is approximately 3㎳(FWHM). This is a relatively long pulse width, compared with other repetitively pulsed $CO_2$ lasers.

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References

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