摘要
由于在高光学深度下,比尔朗伯特(Beer-Lambert)定律的线性近似不再成立,波长调制光谱(WMS)中常用的偶次谐波探测失效。比较研究了适用于高光学深度的对数光谱方法和比值方法,理论研究了这两种方法的测量分辨率以及信号幅度随光学深度变化的规律,研制了一套波长调制光谱光纤甲烷传感器。得到了对数方法中光源功率调制的傅里叶系数表达式;研究了制约对数光谱方法和比值方法分辨率的因素。研究表明,对数光谱方法的测量分辨率高于比值方法2～3个数量级。
Linear approximation of Beer-Lambert law is no longer accepted under high optic depth, so that the popular 2nd harmonic detection in wavelength modulation spectroscopy （WMS） becomes invalid. Logarithmic spectroscopy in WMS is compared with the second to-first harmonic ratio method. The relationship between harmonic signal and optical depth as well the resolution of both is studied theoretically. WMS optical fiber methane sensor at 1650 nm are described. The Foureier coefficients of amplitude modulation of laser in logarithmic spectroscopy are achieved, and the factors affecting the resolution of both methods are studied. The results show that signal-to noise ratio（SNR） with the logarithmic method is 2-3 order larger than that of ratio method.
出处
《中国激光》
EI
CAS
CSCD
北大核心
2009年第2期403-409,共7页
Chinese Journal of Lasers
基金
科技部科技型中小企业技术创新基金
国家自然科学基金面上项目(60707021)资助课题
关键词
光谱学
波长调制光谱
高光学深度
对数光谱
光纤甲烷传感
spectroscopy
wavelength modulation spectroscopy
high optic depth
logarithmic spectroscopy
fiber methane sensor
