通过半导体激光照射采样气体,利用光电检测电路检测前向散射光强,并通过滤波电路、真值转换电路以及后置放大电路,最终将信号进行采样送入微处理器中处理。通过对信号处理电路的各个模块进行动态特性分析,从而找出对系统影响最大的模块部分并提出改进。结果表明,光电检测电路的动态特性对系统的影响最为显著,通过适当减小负载电阻,可有效改善电路的线性动态范围。

A method of signal processing was introduced. When the semiconductor laser irradiated sample atmosphere, the forward scattered light was detected by photoelectric detection circuit and finally sampled into the microprocessor to handle through the filter circuit, RMS converting circuit and post-amplifier circuit. The module part was found which made the greatest impact on the system, by analyzing dynamic characteristic of every module of the signal processing circuit. The result showed that the dynamic characteristics of photoelectric detection circuit was the most significant, and the linear dynamic range of the circuit was improved effectively by decreasing the load resistance.