Research On The Infrared Moisture Testing Method By Fiber Sensor

With the improvement of people's life, we care about such problems as whether the nutrition in the food is enough, whether the environment of home is comfortable and so on. These questions are explained by experience in old time. Nowadays they can be solved by utilizing the intelligent instruments according to the modernization in detection-technology. The method of testing infrared moisture, we discuss in this article, is the foundation theory research in the intelligent instruments' area. Unlike the traditional moisture testing method, it adopts a series of innovations to make itself more portable and cheaper without influence the testing accuracy. Because of these advantages, we can buy it in the future.The article discusses the theory of near infrared reflectance spectroscopy (NIRS), and its application in moisture testing. According to this theory, we design the whole system, and ensure the wavelength of testing and referencing LED. Then we use the fiber sensor as the light way of both emitting and receiving. We design the LED-driver circuit, and amplify the weak signal detected by the photo diode using the principle of Lock-in amplifier. Follow the Lock-in amplifier is an analog to digital converter and a micro process system so as to convert the useful signal in digital forms, analyze these data, and establish the relationship between data and moisture. Thus, we can test the unknown samples after those processes.The conception of this intelligent instrument can not only be used in moisture testing, but can be applied in other material detecting. The only point is finding the absorbing peak and the referencing wavelength. This is the underlying meaning of the topic.