光纤液位仪发射-接收机设计

Design of transmitter-receiver of fiber-optic liquid level sensing device

基于光弹效应，研制了ＩＭ８５－Ⅰ 型光纤液位仪。其传感器内采用光桥式补偿光路，可以克服各种外界因素对测量产生的不利影响。根据补偿结构的要求，其发射－接收机采用双光源交替发光，双探测器同时探测的工作方式。但光源光谱稳定性和光电探测器光电转换的线性对测量结果都会有影响．分析表明：选择发光二极管作光源，硅ＰＩＮ管作探测器．采用Ⅰ－Ｖ光电转换方式，可以满足没计要求。仪器的精度为０．２％．

Based on photoelastic effect,IM85-Ⅰ fiber-optic liquid level sensing device is developed. The sensor of the device uses light bridge to be the compensation structure, and this method can get rid of the bad influences caused by ambient conditions.To meet the demand for compensation structure, the transmitter- receiver uses two light sources working alternatively and two photodetectors working simultaneously.But the stability of the spectrum of the light sources and the non-linearity of photoelectricity transformation affect the measuring results. By analysis, it is shown that choosing LEDs to be the light sources, the silica PIN diodes to be the photodetectors, and the Ⅰ-V transformation to be the photoelectricity transformation style,the designing index can be fulfilled. The precision of this device is proved to be 0.2%.