U型光纤传感器液体浓度测量系统的研究

Investigation of liquid concentration measurement system by U-shaped fiber optic sensor

为了测量液体的浓度,设计制作了一个U型光纤传感系统。在固定光源波长以及恒温的条件下,激光光源发出的光信号在U型光纤传感区域发生全反射,并且得到被测液体参数的调制,通过测量光接收端电信号的大小,可以得到被测液体的浓度。整个实验装置结构简单,主要由激光光源、U型光纤传感探头和光接收器件组成。实验以食盐溶液和蔗糖溶液为测量对象,分析并比较了U型光纤探头在不同曲率半径下的测量结果,浓度分辨率可以达到0.05%。这个装置能够测量透明液体或者适度吸收的半透明液体,具有简单、小巧、稳定性高、价格低廉等优点。测量结果和理论分析十分相符,从而验证了该实验的正确性和可行性。

A U-shaped fiber optic system is designed and made to measure liquid concentration. Since laser light is highly monochromatic and liquid temperature is constant, the concentration of solution hereby is obtained from the meas- urement of electrical signal at the receiving terminal when optical signal occurs total internal reflection in the U-shaped sensing area. The experimental setup is extremely simple, which includes a laser diode coupled to a single-mode optic fi- ber, a U-shaped sensor probe, and a receiving terminal of light signal. Results are presented for NaC1 and sugar aqueous solutions with high resolution on the order of 0.05~. At the same time, the experimental results are compared using dif- ferent radius of curvature of U-shaped probe. The device is used to test liquid concentration of transparent and moderately absorbing liquid, and it has some merits, such as small, simply, high stability and inexpensive. The concentration measurements are in very good agreement with theoretical analysis which verifies the correctness and feasibility of the investigation.