Temperature measurement principle and modulationabsorption spectroscopy were introduced, and the influence of modulation amplitude on gas temperature measurement was analyzed.
介绍了温度测量及调制吸收光谱技术原理，分析了调制幅度对气体温度测量的影响。
2
Optical heterodyne magnetic rotation enhanced velocity modulation spectroscopy (OH-MR-VMS) is an absorption spectroscopic technique for selective detection of the molecular ions.
光外差磁旋转速度调制光谱技术是一种对离子分子选择性测量的高灵敏激光吸收光谱技术。
3
Secondly, spectral modulation techniques are applied into concentration detection because methane has very weak absorption in near-infrared region.