摘要
根据对激光器施加的调制信号是否连续,波长调制光谱分为连续和准连续调制激光吸收光谱技术。为了深入的比较研究这两种方案,设计准连续调制谱专用的软件锁相放大器,将准连续调制信号因间断产生的无效信号滤除后,再对吸收信号解调得到二次谐波信号。与连续激光调制谱软件解调的二次谐波信号进行了比较,结果表明,参数相同,准连续调制谱比连续调制谱的信噪比提高5%、检测限降低11.3%。在滤除无效信号后,准连续调制谱也可以解调出标准的二次谐波信号,因此有望用于与气体线型相关的研究中。该工作为选取更加适用的激光调制谱技术,提供了准确依据。
According to the modulation signal applied on laser diodes, wavelength modulation spectroscopy （WMS） can be divid- ed into continuous wave （CW） WMS and quasi-continuous wave （QCW） WMS. In order to deeply compare CW-WMS and QCW-WMS, we used a specific software-realized lock-in amplifier for continuous and quasi-continuous modulation signal demod-ulation. The invalid signal in quasi-continuous modulation spectrum was filtered off, and then the effective detection signal was demodulated to obtain the second harmonic signal （WMS-2f）. It was compared with the 2f signal demodulated continuous laser modulation spectrum with software. The results show that while the same system parameters are set, the signal-to-noise of the quasi-continuous modulation spectrum is 5 ~ higher than the continuous modulation spectrum with software demodulation meas- urements, and the detection limit is 11.3% lower. And without the invalid signal in quasi-continuous modulation spectrum, the standard WMS-2f signal can be demodulated, which has potential to be used for the investigation of gas absorption profile. This work has provided accurate reference for selections of the laser modulation spectroscopy.
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2013年第12期3419-3424,共6页
Spectroscopy and Spectral Analysis
基金
国家重大科学仪器设备开发专项(2012YQ06016501)
天津市自然科学重点基金项目(10JCZD)资助
关键词
准连续激光调制谱
无效信号
二次谐波信号
软件锁相放大器
Quasi-continuous wave wavelength modulation spectroseopy~ Invalid signal~ Second harmonic signal~ Software-real-ized lock-in amplifier
