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ULTRA-SENSITIVE, REAL-TIME TRACE GAS DETECTION USING HIGH-POWER, MULTI-MODE SEMICONDUCTOR LASER AND CAVITY RINGDOWN SPECTROSCOPY
ULTRA-SENSITIVE, REAL-TIME TRACE GAS DETECTION USING HIGH-POWER, MULTI-MODE SEMICONDUCTOR LASER AND CAVITY RINGDOWN SPECTROSCOPY
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机译:利用高功率,多模式半导体激光和腔衰荡光谱技术进行超灵敏的实时痕量气体检测
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摘要
A highly sensitive trace gas sensor based on Cavity Ring-down Spectroscopy (CRDS) makes use of a high power, multi-mode Fabry-Perot (FP) semiconductor laser with a broad wavelength range to excite a large number of cavity modes and multiple molecular transitions, thereby reducing the detector's susceptibility to vibration and making it well suited for field deployment. The laser beam is aligned on-axis to the cavity, improving the signal-noise-ratio while maintaining its vibration insensitivity. The use of a FP semiconductor laser has the added advantages of being inexpensive, compact and insensitive to vibration. The technique is demonstrated using a laser with an output power of at least 200 mW, preferably over 1.0 Watt, (λ = 400 nm) to measure low concentrations of Nitrogen Dioxide (NO2) in zero air. For single- shot detection, 530 ppt sensitivity is demonstrated with a measurement time of 60 μs which allows for sensitive measurements with high temporal resolution.
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