• Proceedings of the Optical Society of Korea Conference
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• 1989.02a
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• pp.32-35
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• 1989

A 150W industrial Nd:YAG laser was developed. The thermal lensing effect was examined and the radius and position of rear mirror were optimized for higher efficiency. The efficiency of 2.5% was achieved. Also, the performance of laser welding in fine thermocouples and between high-temperature-melting dissimilar metals were investigated.

• The Journal of Natural Sciences
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• v.14 no.2
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• pp.15-23
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• 2004

생활 주변에서 쉽게 구할 수 있는 플래쉬 램프회로를 이용하여 소형 고체레이저를 개발하였다. 레이저 매질로는 Nd:YAG가 사용되었으며, 수동형 큐스위칭 $동작^{[1-4]}$을 위하여 Cr:YAG 결정이 사용되었다. 플래쉬 램프 회로로는 코닥 일회용 카메라, 후지 일회용 카메라, 자동차 장식용으로 사용되는 훠링의 스파크 라이트를 사용하였다. 레이저의 펌핑 에너지에 따른 레이저 출력의 변화를 측정하고, 수동형 Q-switch로 사용되는 Cr:YAG의 도핑 농도에 따른 레이저 출력을 측정하였다. 또한 출력경의 투과율에 따른 레이저 출력을 측정하여 레이저 출력경의 최적투과율을 실험적으로 구하였다.

• Korean Journal of Optics and Photonics
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• v.18 no.4
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• pp.270-273
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• 2007

We have investigated the output characteristics of the 946 nm Nd:YAG laser which is longitudinally pumped by a fiber coupled laser diode. The temperature of a Nd:YAG crystal mount was kept constant by a controller with thermoelectric cooler. As a result, we measured more intense output at a low temperature, and then the maximum output power was measured to be 870 mW when the pumping power and the temperature were 9.95 W and $5^{\circ}C$, respectively. It appeared that output was decreased above 10 W pump power because of the thermal effects in gain medium.

• Journal of the Korean Society of Radiology
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• v.14 no.5
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• pp.695-703
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• 2020

The use of medical devices is increasing due to the development of medical technology. Among medical devices, it is often used in the human body for graft and treatment. Therefore, in medical institutions, various sterilization methods according to the type and material of medical devices are applied to prevent infection. Hydrophosphite (HA) materials are the most popular in bone grafts. We would like to present a sterilization method using Q-switch Nd:YAG laser with high output energy among non-ionizing radiation suitable for small medical devices. In this study, sterilization power was most ideally shown at UV wavelengths of 1.5 W, 266 nm, and 10 pulses. Different wavelength bands; infrared and visible light; showed passive sterilization, and ultraviolet A and C showed differences in sterilization according to the pulse. In laser sterilization were differences that found according to the wavelength bands and pulses.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.3
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• pp.381-390
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• 2004

The purpose of this in vitro study was to investigate the effects of Nd:YAG laser irradiation and fluorides on acid drink demineralized enamel. The materials were 30 freshly extracted permanent premolars with intact smooth enamel surfaces. They were demineralized with Coca-cola at $37^{\circ}C$ for 12hours and then irradiated by Nd:YAG laser with 6W power, $50mJ/cm^2$ energy density, and 20Hz pulse repetition. After laser irradiation, teeth were treated by three kinds of fluorides; (1)0.05% NaF fluoride solution (2)1.23% APF gel and (3)0.1%F fluoride varnish, microhardness(VHN) and Diagnodent scores were measured and the surfaces of each treated specimens were also observed with SEM under 1500 magnification. The results were as follows: 1. In the change of microhardness(VHN), it decreased to 34.68% from the initial micrhardness, increased to 78.37% after laser irradiation and increased to 82.62% after fluoride treatment, there were significant differences except when it was irradiated and treated with fluoride(P<0.05). 2. In the change of Diagnodent scores, it was decreased to 28.08% from the initial scores after demineralization, and then increased to 59.81% after laser irradiation, and increased to 82.17% after fluoride treatment. Scores were different significantly between the scores of initial, demineralization, laser irradiation and fluoride treatment(P<0.05). All the scores were not different significantly between fluoride types. 3. SEM observation showed that the lased enamel surfaces after demineralization were thermally degenerated and showed molten lava-like appearance and crater with cracks and many microholes.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.111-111
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• 2003

• Proceedings of the Korean Society of Laser Processing Conference
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• 2003.05a
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• pp.84-87
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• 2003

• Proceedings of the Optical Society of Korea Conference
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• 2007.02a
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• pp.30-31
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• 2007

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.6
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• pp.1141-1149
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• 2009

Pulse style Nd: YAG Laser is suitable in skin remaking treatment, in compliance with the ramp continuous oscillation until of course normal takeoff, the Q-switch and mode motive takeoff the takeoff form which is various is possible and it is coming to be widely used in microsurgery and skin remaking promotion. According to therapeutic objective very it is important to control a energy density. Control of energy density the method which controls the pulse repetition rate of Laser output is mainly used. From the research which it sees pulse style Nd: It will be able to control the pulse repetition rate of YAG, the 2nd harmonic occurrence Laser (second harmonic generation: SHG) with the energy part of the light-wave which is a footnote wave number will hold and nonlinear decision it propagates and is converted by energy of the light-wave which is a footnote wave number the actual condition which and it applies the second harmonic occurrence in compliance with a secondary nonlinearity it leads and until skin deep part therapeutic possibility is the thing it will be able to observe simply.

• The Journal of Natural Sciences
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• v.14 no.2
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• pp.25-31
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• 2004

레이저 거리 측정기나 화생탐지 라이다용으로 사용할 수 있는 눈에 안전한 적외선 레이저 광원을 개발하였다. 펌프레이저로는 소형 플래쉬 램프로 구동되는 Nd:YAG 레이저를 사용하였으며, OPO(Optical Parametric Oscillator) 결정으로는 Flux 성장된 KTP를 사용하였다. OPO 송진기는 레이저 공진기 내부에 설치하여 비선형 광학 현산에 의한 파라메트릭 발진이 쉽게 일어나도록 하였다. 효율적인 파라메트릭 발진을 위해서 Type II 비임계 위상정합$(\theta=90^{\circ},\;\phi = 0^{\circ})$을 사용하여 공진기를 구성하였다. Nd:YAG 레이저는 Cr:YAG 결정을 사용하여 수동형 큐-스위칭 되었으며 OPO 출력은 1mJ 정도이었다. OPO 펄스폭은 4ns로서 수동형 큐스위칭 레이저 펄스폭보다 20% 정도로 작았다. OPO 출력의 펄스폭이 펌프레이저의 펄스폭 보다 작은 것은 이론적 계산을 통하여 확인할 수 있었다.