用LED作光源的光纤乙炔气体传感器的研究

Research on the Optic Fiber C_2H_2 Sensor Using LED as the Light Source

基于气体的近红外吸收机理,介绍了一种用LED作光源的光谱吸收型光纤乙炔气体传感器。该系统利用布拉格光纤光栅和压电陶瓷(PZT)的窄带滤波特性,对宽带光源LED进行波长调制,获得与乙炔气体吸收峰相对应的窄带反射出射光。利用谐波检测原理,获得探测器输出信号的二次谐波信号,以此二次谐波信号与光纤光栅透射光强的比值作为系统的输出,消除了吸收系数随环境的变化、光路不稳定因素的干扰和光源光率的波动等因素对测量精度的影响,实现对气体较高灵敏的检测。理论与实验表明,该系统稳定性和重复性好,可以对变压器油中的乙炔气体进行有效检测。

Based on the near infrared spectral absorption of gases,a spectral absorption-tybe optic fiber sensor for acetylene using LED as the light source was demonstrated.A light emitting diode was used as the broadband source,the wavelength of the LED was modulated by the fiber bragg grating and piezoelectric ceramics（PZT）to obtain the narrowband reflection output light using their filtering characteristics.Basd on the principle of harmonic detection,the second harmonic signal of the dector was measured,the ratio of the second harmonic signal and the transmission output of the source was regarded as the output of the system,which can be used for eliminating the interference to the high sensitivity detection of the change of absorb coefficient with the environment,the interference of the optical unstabling route and the fluctuation of the led power and so on,then the high sensitivity detection of gas density can be realized.Theory and experiment indicate that the stability and reproducibility of the system are so well that it can detect the acetylene with high efficient in the transfer oil.