CAJ | 학술논문

基于可调谐二极管激光吸收光谱技术(TDLAS)的大气痕量气体检测方法具有高灵敏度和实时响应等特点.根据半导体激光器的特性,在进行波长直接调制时振幅调制也会伴随发生,并产生残余振幅调制噪声.在吸收线宽较大的检测条件下其影响不可忽视.为探讨伴随发生的振幅调制对检测下限的影响,提出了一种同时考虑波长和振幅调制的二次谐波信号分析及提取方法,并以二次谐波信号峰谷差值作为系统的检测信号,实施信噪比及检测下限的计算.结果表明,残余振幅调制噪声是影响检测下限的重要因素.
기우가조해이겁관격광흡수광보기술(TDLAS)적대기흔량기체검측방법구유고령민도화실시향응등특점.근거반도체격광기적특성,재진행파장직접조제시진폭조제야회반수발생,병산생잔여진폭조제조성.재흡수선관교대적검측조건하기영향불가홀시.위탐토반수발생적진폭조제대검측하한적영향,제출료일충동시고필파장화진폭조제적이차해파신호분석급제취방법,병이이차해파신호봉곡차치작위계통적검측신호,실시신조비급검측하한적계산.결과표명,잔여진폭조제조성시영향검측하한적중요인소.
Atmospheric trace gas detection method based on tunable diode laser absorption spectroscopy (TDLAS) has high sensitivity and real-time response characteristics.According to the characteristics of semiconductor lasers,amplitude modulation and residual amplitude modulation noise can also occur when the wavelength is modu lated directly and the impact can not be ignored in the case of larger absorption linewidth.In order to investigate the impact of residual amplitude modulation to SNR and detection limit,a second harmonic signal analysis and extraction method is introduced with taking into account simultaneously the wavelength and amplitude modulation.The difference between peak and valley of second harmonic signal are utilized for the system detection signal to calculate the SNR and detection limit.The results show that residual amplitude modulation noise is an important factor to affect the detection limit.