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利用室温下单模运行的近红外半导体二极管激光,报导了波长调制共振光声光谱结合二次谐波探测技术.实验系统应用到乙炔探测,在1个标准大气压和3毫瓦平均光功率以及3毫秒锁相积分时间条件下其探测灵敏度可达10ppm(体积比),归一化到激光功率和系统带宽最小可探测吸收为4.0×10-8Wcm-1/Hz,并且实验中发现系统最佳压力响应值在2.66×104Pa附近.本实验装置可有效的消除光声光谱系统中常见的窗片和光声腔壁吸收入射光而引起的背景噪声.此外,相对于其他方法我们描述的基于半导体激光共振光声光谱具有很大的优点,为进一步发展便利、实用、便携式环境监测仪器奠定了坚实的基础.
The use of near-infrared semiconductor diode lasers operating at single-mode operation at room temperature reported wavelength-modulated resonant photoacoustic spectroscopy combined with second-harmonic detection techniques. The experimental system was applied to acetylene detection at 1 standard atmospheric pressure and 3 mW average optical power and 3 The detection sensitivity of up to 10 ppm (volume ratio) under millisecond phase-lock integration time, normalized to the laser power and the minimum detectable absorbance of the system bandwidth of 4.0 × 10 -8 W cm -1 / Hz, and experiments found that the system optimal pressure The response value is near 2.66 × 104Pa.This experimental device can effectively eliminate the background noise caused by the common windows and the photoacoustic cavity wall absorbing the incident light in the photoacoustic spectroscopy system.In addition, compared with the other methods, we describe the semiconductor laser based on the resonant light Acoustic spectroscopy has great advantages, laying a solid foundation for the further development of convenient, practical and portable environmental monitoring instruments.