甲烷气体检测中半导体激光器的温度控制

Semiconductor laser temperature control in methane gas detection system

采用可调谐半导体激光吸收光谱技术(TDLAS)的气体浓度检测系统,其半导体激光器(LD)的输出波长在注入电流恒定的情况下受温度影响很大。高精度的LD温度控制能够保证光源输出光谱的中心波长位于待测气体吸收峰。针对LD温度控制技术的特点,采用两级温度控制的思想,一级保证LD外部工作环境温度稳定在一个小的区间内,另一级是以LD组件热电制冷器(TEC)和热敏电阻(RT)结合模拟的比例—积分(PI)环节来实现温度稳定。实验结果表明,设计的温度控制系统具有良好的稳定性,检测精度可达0.01℃,满足实验的要求。

In the gas concentration detection system adopting tunable diode laser absorption spectroscopy（TDLAS）,the output wavelength of the diode laser（LD） is subjected to great impact by temperature under a constant injection current,and high-precision temperature control can ensure that the center wavelength can be located on the gas absorption peak.This paper introduces the use of two-stage temperature control,as required by the characteristics of LD temperature control,one capable of allowing the external environmental temperature of LD to be stabilized at a small interval,and the other capable of achieving temperature stability based on LD components of thermoelectric cooler（TEC） and thermistor（RT） combined with proportion-integral（PI） links.Experimental results show that the temperature control system with a better stability and measurement accuracy up to 0.01 ℃ is up to the test requirements.