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레이저-다이오드로 펌핑하는 670 nm-Nd:GdVO₄/LBO 적색 레이저의 동작 특성
변성욱,추한태,박차곤,김규욱,이상호 한국물리학회 2011 새물리 Vol.61 No.2
We have investigated the operational characteristics of a laser-diode-end pumped 1.34-μm Nd:GdVO₄laser and its intracavity frequency-doubled 670-nm red laser by inserting a LBO (lithium triborate, LiB3O5) nonlinear crystal into either a linear or a V-type folded cavity. When the cavity length of the linear cavity was 88 mm and the temperature of the LBO was kept at 28℃ for an incident pump power of 19 W, we obtained a 670-nm laser with a maximum output power of 1.29W, which resulted in an optical efficiency of 6.8 %. The fluctuation (rms) of the average output was measured to be 2.4 %. Also, when the cavity length of the V-type folded cavity was 173 mm and the temperature of the LBO was kept at 29℃ for an incident pump power of 17.5 W, we obtained a 670-nm laser with a maximum output power of 1.29 W, which resulted in an optical efficiency of 2.9 %. The fluctuation (rms) of the average output was measured to be 1.16 %. Although the laser output power and the conversion efficiency of the V-type folded cavity are lower than those of the linear cavity, the power stability of the V-type folded cavity is found to be better than that of the linear cavity. Also, the beam quality parameter M² and the beam divergence angle of a 0.6-W,670-nm red laser were measured to be 2.79 and 12.8 mrad respectively, for the linear cavity. 레이저 다이오드(LD)로 단면 펌핑하는 1.34 -Nd:GdVO₄레이저를 구성하고, LBO (Lithium triborate, LiB3O5) 비선형 결정을 이용한 내부 공진기 주파수 배가를 통하여 670 nm-Nd:GdVO₄/ LBO 적색 레이저를 발진시키고 동작 특성을 조사하였다. 직선 공진기 구조에서 공진기 길이가 88 mm, 펌핑 출력이 19 W, LBO의 온도가 28 ℃일 때 측정한 670 nm 적색 레이저 출력은 최대 1.29 W이었고, 이때 광 변환 효율은 6.8 %이다. 출력 변동의 rms 값은 2.4 %로 측정되었다. V-자형 접힘 공진기 구조에서 공진기 총길이가 173 mm, 펌핑 출력이 17.5 W, LBO의 온도가 29 ℃일 때 670 nm 적색 레이저 출력은 최대 0.6 W이었고, 이때의 광 변환 효율은 2.9 %, 출력 변동의 rms 값은 1.16 %로 측정되었다. 직선형 공진에 비하여 출력과 변환 효율은 낮지만 안정성은 우수함이 확인되었다. 한편 직선 공진기 구조에서 670 nm 레이저의 출력이 0.6 W일 때 빔의 질 변수 M2와 빔 발산각은 각각 2.79와 12.8 mrad으로 나타났다.
레이저-다이오드로 펌핑하고 Cr4+:YAG 포화흡수체를 이용하는 수동형 Q-스위칭된 1.06 ㎛-Nd:GdVO4 레이저의 동작 특성
변성욱,추한태,박차곤,김규욱,이치원 한국물리학회 2010 새물리 Vol.60 No.2
We have investigated the operational characteristics of a laser-diode-pumped passively Q-switched 1.06-㎛ Nd:GdVO4 laser with a Cr4+:YAG saturable absorber by using simple plano-concave and plano-plano resonators. Based on the ABCD ray matrix theory, two resonators containing thermal lens in both the laser medium and the saturable absorber were analyzed. An analytical relation between the pulse repetition rate and the absorbed pump power is given for a passively Q-switching laser and show good consistency with the experiment results obtained using a Nd:GdVO4 laser. The dependencs of the operational parameters on the pump power and on the output coupling were also investigated experimentally. By empolying a plano-concave resonator with an output coupling of T=10 %, a radius of cavature of 200 mm, and a cavity length of 56 mm, we obtained a maximum average output power of 2.5 W at a absorbed pump power of 15 W, leading to an optical conversion efficiency and a slope of efficiency of 17% and 18%, respectively. The pulse width and the pulse repetition rate of laser were 15.7 ns and 93 kHz, respectively, and the single pulse energy and the peak power were found to be 27 μJ and 1.72 kW, respectively. 레이저-다이오드로 펌핑하는 간단한 평면-오목 및 평면-평면 형태의 공진기를 구성하고 Cr4+:YAG 포화흡수체를 이용한 수동형 Q-스위칭 1.06 ㎛-Nd:GdVO4 레이저의 동작 특성을 조사하였다. ABCD 광선 행렬 이론을 이용하여 레이저 매질 및 포화흡수체의 열렌즈가 포함된 두 가지 형태의 공진기를 분석하였으며 수동형 Q-스위칭 레이저에 대하여 흡수된 펌프 출력과 펄스 반복률 사이의 해석적 관계가 Nd:GdVO4 레이저 실험과 잘 일치함을 보이고 있다. 또한 펌프 출력과 출력거울의 투과율에 대한 동작 파라메터 의존성을 실험적으로 조사하였다. 출력거울의 곡률반경이 200 mm이며 투과율 10 %이고 공진기 길이가 56 mm인 평면-오목 형태의 공진기로부터 15 W의 흡수된 펌프 출력에 대하여 2.5 W의 최대 평균 출력을 얻었으며, 광변환 효율 및 기울기 효율은 각각 17 % 및 18 %로 측정되었다. 레이저 펄스폭과 반복률은 각각 15.7 ns와 93 kHz이었으며 그때의 단일-펄스 에너지 및 첨두 출력은 각각 27 μJ 및 1.72 kW 이었다.
PVC 여과지를 이용한 금속 분석방법에 대한 정확도와 정밀도 평가
변성욱 ( Seong Uk Byun ),최상준 ( Sang Jun Choi ) 한국산업보건학회 2016 한국산업보건학회지 Vol.26 No.1
Objectives: This study was conducted to evaluate the accuracy and precision of airborne metal analysis using polyvinyl chloride(PVC) membrane filter by pretreatment methods. Methods: A total of 75 spiked PVC samples for Cr, Fe and Mn ranged from 6 ug/sample to 40 ug/sample were used to evaluate recovery rates for three pretreatment methods: acid extraction, hot plate ashing and microwave digestion. For Mn, an additional 75 spiked mixed cellulose ester(MCE) membrane filters were analysed to compare the recovery rates of PVC samples. All samples were analysed with an inductively coupled plasma optical emission spectrometer(ICP-OES) and manganese samples were additionally analyzed by atomic absorption spectrometer(AAS). Results: The overall mean recovery rates of PVC samples for Cr, Fe and Mn were 90% or higher regardless of pretreatment methods, but there were statistically significant differences in recovery rates for Cr(p<0.05) and Mn(p<0.01) samples by pretreatment methods. The biases and the coefficient variations of PVC samples for three metals pretreated with three kinds of pretreatment methods ranged from 1.7% to 4.7% and from 1.6% to 6.5%, respectively. The manganese PVC samples pretreated by microwave digestion and analyzed with ICP-OES had the lowest bias at 1.9% and also showed lower bias than the bias for MCE samples, 2.7%. Conclusions: In order to accurately analyze the metals sampled with PVC membrane filters, microwave digestion and ICP-OES can be recommended.