• Journal of the Optical Society of Korea
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• 제13권3호
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• pp.335-340
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• 2009

Ultrashort pulse laser drilling of polycarbonate track-etched membrane (pTEM) material was used to fabricate a mouse embryo cell trapping device. Holes with a diameter of $2{\mu}m$ to $5{\mu}m$ were fabricated on a $10{\mu}m$ thick membrane using a femtosecond laser with a 150 fs pulse width and 775 nm wavelength and multiple-pulse irradiation. In cell trapping tests, the overall cell occupancy of the machined holes in the fabricated pTEM was found to be more than 80%. The results of a single pulse and multiple pulse irradiation were compared in terms of the surface quality. It was generally found that a single pulse with high energy was less desirable than irradiation with multiple pulses of lower energy.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권12호
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• pp.568-572
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• 2003

A longitudinal discharge heated copper vapor laser with internal diameter 28 mm and discharge length 1.3 m has been constructed and tested. At the discharging voltage 15.2 kV, pulse repetition rate 10 kHz, buffer gas pressure 40 mbar, and internal temperature of the laser plasma tube $1520^{\circ}C$, it delivers more than 30 W average laser outputs.

• Journal of Welding and Joining
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• 제6권1호
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• pp.21-27
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• 1988

This paper describes weldability of dissimilar metal plates with YAG laser for the use of a small-size electronic spring parts. Effects of welding conditions, combination of plates, thickness of upper plate are examined in relation to welding strength and microstructure of welded region. The obtained results are summarized as follows. Welding defects such as cavity and crack showed a tendency to easily occur in the case where 1) pulse duration is short, 2) laser power is high, 3) PBS plate with high thermal diffusivity is used for lower plate. Among these defects, the occurrence of cavity cased a drop of welding strength. This results from the reduction of welding area between upper and lower plates. In SK-5/SUS304 plates (thickness: 0.2/0.4mm/, welding strength was the highest in welding conditions: laser power is 30J/pulse, pulse duration 9ms, amount of defocus +2mm.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.185-186
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• 2009

• 전기의세계
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• 제29권2호
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• pp.118-128
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• 1980

The properties of plasmas produced by high power glass laser were investigated with various methods of diagnostics. Electron temperature was estimated by measurement of soft X-ray, and ion temperature was estimated by measurement of the time-of-flight of ion. The measurement of incident and reflected laser light, and Schlieren and shadowgragh methods were also used. No influence of laser pulse duration on the temperature was observed in the case of durations 2, 4 and 10 nsecs. The effective heating of plasma occurred in about 2 nsec of beginning of incident laser pulse. The experimental results for fast rising laser pulse were discussed and the influence of resetime of laser pulse on the heating of plasma was described. Neutrons produced by irradiating laser beam to solid deuterium target were detected.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.514-517
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• 1996

Zero current switching(ZCS) series resonant converter is used to control laser power density in a pulsed Nd:YAG laser power supply. The high power and high repetition rate paused Nd:YAG laser is designed and fabricated to control current pulse width and pulse repetition rate in the double elliptical laser oscillator. In order to find out operational characteristics of pulsed Nd:YAG laser, the electrical properties of driving power supply and laser output power are investigated and experimented by changing of the current pulse width from 200uS to 350uS(step 50uS) and pulse repetition rate range of 500pps(pulse per second) to 1150pps. From that result, we obtaind maximum efficiency of 1.83% and maximum laser output or 220W at the condition of 350 uS and 1150pps with one Nd:YAG rod), and obtained that of more than 400W with two laser head connecting series.

• KIEE International Transactions on Electrophysics and Applications
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• 제2C권6호
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• pp.304-308
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• 2002

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.

• 한국레이저가공학회:학술대회논문집
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• 한국레이저가공학회 1998년도 추계학술발표대회 초록개요집
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• pp.24-28
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• 1998

• 한국정보통신학회논문지
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• 제8권4호
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• pp.946-949
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• 2004

분포궤환 색소레이저(DFDL： Distributed feedback Dye Laser)로부터 80 uJ의 단일 극초단 펄스를 얻고, 이를 2단의 증폭기와 betune cell에 의한 다단 증폭으로 높은 출력을 얻은 후 BBO를 사용, 자외선 영역의 제 2고조파를 얻었다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 춘계종합학술대회
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• pp.339-341
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• 2004

Self Q-switching에 의한 분포궤환 색소레이저(DFDL: Distributed Feedback Dye Laser)로부터 80uJ의 단일 극초단 펄스를 얻고, 이를 2단의 증폭기와 betune cell에 의한 3단 증폭으로 높은 출력을 얻은 후 BBO를 사용, 자외선 영역의 제 2고조파를 얻었다.