Research On The Near Infrared Moisture Measurement Instrument Based On The LED Infrared Light

Water is the most common substance in nature and moisture is one of the most important measurement parameters in many industrial processes. For example, excessive moisture will make the grain get deterioration and moisture of sinter mixture can directly impact the quality of sintering process. With the improvement of the level of modern industrial automation, traditional off-line moisture detection methods have been unable to meet the online real-time measurement needs, so how to get the moisture value rapidly and accurately has become an important topic of industrial parameters measurement.The method of near infrared moisture measurement is based on the Lambert-Beer's law. Compared with the traditional near infrared moisture instrument, InGaAs photodiode has been used as the photoelectric sensor and near infrared LED lights, which can be modulated, have been used to substitute the original halogen lamps. The circuit of LED driver and photoelectric signal detection need to be designed. The structure of sensor probe and the program of PC real-time interactive applications need to be designed too. As the LED power is far less than halogen, the difficulty of photoelectric signal detection will also increase. The lock-in amplifier has been used to achieve the detection of weak optical signal.The optical system based on LED lights, the LED driving circuit and the lock-in amplifier circuit have been completed. The measure of weak signal has been achieved and the system of moisture detecting has been established, which can save power consumption and the system volume, improve the life of operation. Within the range of the detection system, preliminary results of the moisture measurement of sinter mixture have been achieved in this article...