• Title/Summary/Keyword: laser spectroscopy

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Measurement of the Radiative Quantum Efficiency of a Solid-State Laser Using Photoacoustic Spectroscopy (광음향 분광을 이용한 고체레이저의 방사양자효율 측정)

  • Kim, Byung-Tai
    • Korean Journal of Optics and Photonics
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    • v.26 no.2
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    • pp.98-102
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    • 2015
  • The radiative quantum efficiency of a solid-state laser was measured by photoacoustic spectroscopy with a PZT as the detector. The radiative quantum efficiency was about 58.3 % for a laser-diode pumped Nd:S-VAP laser under lasing conditions. The measurement of radiative quantum efficiency was presented as an effective method for the optimization of a laser resonator.

Analysis of RBC Damage Using Laser Tweezers Raman Spectroscopy (LTRS) During Femtosecond Laser Optical Trapping (레이저 트위저 라만 분광을 이용한 펨토초 광포획 동안의 적혈구 손상 분석)

  • Ju, Seong-Bin;Pyo, Jin-U;Jang, Jae-Yeong;Lee, Seung-Deok;Kim, Beop-Min
    • Proceedings of the Optical Society of Korea Conference
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    • 2008.02a
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    • pp.453-454
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    • 2008
  • femtosecond laser를 광원으로 하는 optical tweezers는 광포획 뿐만 아니라 비선형 현상을 발생시킬 수 있다는 장점을 가지고 있다. 그러나 높은 첨두 출력에 의하여 포획된 세포는 쉽게 손상되어 질 수 있다. 본 논문에서는 LTRS(Laser Tweezers Raman Spectroscopy)를 통하여 femtosecond laser와 CW laser에 의한 optical tweezers 상에서의 optical damage를 비교, 분석하였다.

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Qualitative and Quantitative Analysis of Space Minerals using Laser-Induced Breakdown Spectroscopy and Raman Spectroscopy (레이저 유도 분해 분광법과 라만 분광법을 이용한 우주 광물의 정성 및 정량 분석 기법)

  • Kim, Dongyoung;Yoh, Jack J.
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.6
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    • pp.519-526
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    • 2018
  • In order to analyze space resources, it had to be brought to earth. However, using laser-induced breakdown spectroscopy(LIBS) and Raman spectroscopy, it is possible to analyze qualitative and quantitative analysis of space minerals in real time. LIBS is a spectroscopic method in which a high energy laser is concentrated on a material surface to generate a plasma, and the emitted light is acquired through a spectroscope to analyze the atomic composition. Raman spectroscopy is a spectroscopic method that analyzes the molecular structure by measuring scattered light. These two spectroscopic methods are complementary spectroscopic methods for analyzing the atoms and molecules of unknown minerals and have an advantage as space payloads. In this study, data were analyzed qualitatively by using principal component analysis(PCA). In addition, a mixture of two minerals was prepared and a quantitative analysis was performed to predict the concentration of the material.

Species Concentration Measurement Using Diode Laser Absorption Spectroscopy (I) (다이오드 레이저를 이용한 광흡수 농도 계측 기법 (I))

  • Ahn, Jae-Hyun;Kim, Yong-Mo;Kim, Se-Won
    • Journal of the Korean Society of Combustion
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    • v.9 no.3
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    • pp.27-35
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    • 2004
  • Diode laser absorption sensors are advantageous because they may provide fast, sensitive, absolute, and selective measurements of species concentration. These systems are very attractive for practical applications owing to its compactness, resonable cost, robustness, and ease of use. In addition, diode lasers are fiber-optic compatible and thus enable simultaneous measurements of multiple species along a line-of-sight. Recent advances of room-temperature, near-IR and visible diode laser sources for telecommunication, optical data storage applications make it possible to be applied for combustion diagnostics based on diode laser absorption spectroscopy. Therefore, combined with fiber-optics and high sensitive detection strategies, compact and portable sensor systems are now appearing for variety of applications. The objectives of this research are to develope a new gas sensing system and to verify feasibility of this system. Wavelength and power characteristics as a function of injection current and temperature are experimentally found out. Direct absorption spectroscopy has been demonstrated in these experiments and has a bright prospect to this diode laser system.

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Detection of Methane and Ethane by Continuous-Wave Cavity Ring-Down Spectroscopy Near 1.67 μm

  • Oh, Myoung-Kyu;Lee, Yong-Hoon;Choi, Sung-Chul;Ko, Do-Kyeong;Lee, Jong-Min
    • Journal of the Optical Society of Korea
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    • v.12 no.1
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    • pp.1-6
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    • 2008
  • We report the simple detection method of the small hydrocarbons, methane and ethane, by continuous-wave cavity ring-down spectroscopy near 1.67 ${\mu}m$ using an external cavity diode laser. The absorption lines of methane between 6002.48 $cm^{-1}$ and 6003.37 $cm^{-1}$ and ethane between 5955.65 $cm^{-1}$ and 5956.4 $cm^{-1}$ have been resolved and employed for the gas detection. The largest absorption cross sections were found to be 6.5$\times10^{-20}cm^2$ and 7.4$\times10^{-21}cm^2$ for methane and ethane, respectively, in each spectral range. The minimum detectable absorption limit of our spectrometer was 4.8${\times}10^{-9}cm^{-1}$/$\sqrt{Hz}$, which corresponds to the detection limits of 3 ppb/$\sqrt{Hz}$ and 27 ppb/$\sqrt{Hz}$ for methane and ethane, respectively. The near-IR continuous-wave cavity ring-down spectroscopic detection method of the small hydrocarbons can be applied for medical diagnosis and environmental monitoring as a fast and convenient method.

Technical tendency of electric field measurements in glow discharge plasmas using laser spectroscopy (레이저를 이용한 방전 플라즈마중의 전계측정 기술 동향)

  • Choi, Y.W.;Bowden, M.;Muraoka, K.
    • Proceedings of the KIEE Conference
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    • 1997.07e
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    • pp.1663-1665
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    • 1997
  • Direct measurements of electric fields in a glow discharge are difficult because the measurement method should be sensitive to the electric field and non-intrusive. Laser spectroscopy is very suitable in that it is non-intrusive and allow in-situ measurements to be made. In this report, the measurement techniques of electric fields in glow discharge using laser spectroscopy were described.

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Double Pulse Raman-Laser Induced Plasma Spectroscopy System for Space Exploration (우주 탐사를 위한 이중펄스 라만-레이저 유도 플라즈마 분광 시스템 개발 연구)

  • Yang, Jun-Ho;Yoh, Jai-Ick
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.48 no.6
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    • pp.479-487
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    • 2020
  • A new double-pulse laser system that combines Raman and laser induced plasma spectroscopy (LIPS) in a single unit is proposed. The study attempts to enhance the laser induced plasma signals while simultaneously extracting the desired molecular signals from Raman spectroscopy. In low pressure conditions such as the lunar atmosphere, the measuring of plasma emission is hard because of the low electron density and short persistence time causing a rapid plasma expansion. Furthermore, in the integration of the detecting system aimed at space exploration, the minimization of laser system is important in terms of the payload mass. Simultaneous molecular and atomic detection that gave highly resolved spectral data at pressure below 0.07 torr is demonstrated amongst eight rock samples test. The plasma stacking produced from the double-pulse laser enhanced the signal intensity of calcium and oxygen lines in calcite matrix by twofold, compared to a conventional LIPS.

Study on the spectroscopic reconstruction of explosive-contaminated overlapping fingerprints using the laser-induced plasma emissions

  • Yang, Jun-Ho;Yoh, Jai-Ick
    • Analytical Science and Technology
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    • v.33 no.2
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    • pp.86-97
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    • 2020
  • Reconstruction and separation of explosive-contaminated overlapping fingerprints constitutes an analytical challenge of high significance in forensic sciences. Laser-induced breakdown spectroscopy (LIBS) allows real-time chemical mapping by detecting the light emissions from laser-induced plasma and can offer powerful means of fingerprint classification based on the chemical components of the sample. During recent years LIBS has been studied one of the spectroscopic techniques with larger capability for forensic sciences. However, despite of the great sensitivity, LIBS suffers from a limited detection due to difficulties in reconstruction of overlapping fingerprints. Here, the authors propose a simple, yet effective, method of using chemical mapping to separate and reconstruct the explosive-contaminated, overlapping fingerprints. A Q-switched Nd:YAG laser system (1064 nm), which allows the laser beam diameter and the area of the ablated crater to be controlled, was used to analyze the chemical compositions of eight samples of explosive-contaminated fingerprints (featuring two sample explosive and four individuals) via the LIBS. Then, the chemical validations were further performed by applying the Raman spectroscopy. The results were subjected to principal component and partial least-squares multivariate analyses, and showed the classification of contaminated fingerprints at higher than 91% accuracy. Robustness and sensitivity tests indicate that the novel method used here is effective for separating and reconstructing the overlapping fingerprints with explosive trace.