基于聚酰亚胺涂覆技术的FBG湿度计性能研究

Study on Performance of FBG Hygrometer Based on Polyimide Coating Technology

摘要:

为研究聚酰亚胺涂覆的光纤布拉格光栅(FBG)湿度计在使用过程中的性能特征,利用饱和盐溶液控制环境湿度,测试了FBG中心波长随相对湿度的变化特征,研究了温度对湿度灵敏度系数的影响。结果表明:(1)在34.7%~93.1%相对湿度范围内,聚酰亚胺涂覆的FBG湿度计对湿度变化均具有较好的响应。在升湿、降湿过程,中心波长与相对湿度具有明显的线性关系,湿度灵敏度系数范围为5.1~15.7 pm/%。(2)聚酰亚胺涂覆厚度越大,湿度灵敏度越高,中心波长与相对湿度的线性相关程度也更高。(3)以2号和4号湿度计为例,当温度变化20 ℃时,两个湿度计湿度灵敏度系数的相对误差分别为4.82%和3.11%,温度对湿度灵敏度系数的影响很小,在实际测量中,温度变化不大时可忽略其对湿度灵敏度系数的影响。(4)以2号和4号湿度计为例,通过室内试验得到了温度灵敏度系数和湿度灵敏度系数,建立了用于同时测量温度与湿度的数学矩阵,使FBG湿度计能够实现对环境温度和湿度的同时测量。

Abstract:

In order to study the performance characteristics of polyimide-coated Fiber Bragg Grating (FBG) hygrometer, the saturated salt solution was used to control the ambient humidity, and the variation of FBG center wavelength with relative humidity was tested. The effect of temperature on the sensitivity coefficient of humidity was studied, and the simultaneous measurement of temperature and humidity by this hygrometer was achieved. The results showed that: (1) Within the humidity range of 34.7% to 93.1% in the experimental design, the polyimide-coated FBG humidity meter had a good response to humidity changes. During the humidification and dehumidification processes, the center wavelength exhibited a clear linear relationship with relative humidity, and the humidity sensitivity coefficient ranged from 5.1 to 15.7 pm/%. (2) The thicker the polyimide coating, the higher the humidity sensitivity, and the linear correlation degree between the center wavelength and relative humidity was also higher. (3) Taking the humidity meters No.2 and No.4 as examples, the relative errors of the humidity sensitivity coefficients of the two humidity meters due to a 20 ℃ temperature change were 4.82% and 3.11% respectively. The influence of temperature on the humidity sensitivity coefficient was very small, and its effect on the humidity sensitivity coefficient can be ignored when the temperature change was not significant in actual measurement. (4) Taking the humidity meters No.2 and No.4 as examples, the tempe-rature sensitivity coefficient and humidity sensitivity coefficient were obtained through indoor experiments, and a mathematical matrix for simultaneously measuring temperature and humidity was established, enabling the FBG humidity meter to achieve simultaneous measurement of environmental temperature and humidity.