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With the continuous development of industrial production , people are increasingly concerned about the quality of the product , is one of the detection of the moisture content in the material . In the paper industry , in order not to damage the paper , often using a resistance moisture meter or infrared manner to detect the moisture content of the paper products . In this paper, using optical fiber sensor near infrared paper moisture meter , modular fiber bundle sensor instead of conventional optical portion of the infrared moisture meter , making it the method of transmitting and receiving optical path of the signal , and the use of dual-source dual optical path objects moisture measurement, then the test signal and the reference signal obtained from the optical fiber sensor , two signal ratio calculation effectively eliminates the power variation due to the light source , the optical fiber bend , the surface is not flat , such as interference . Sent to the detection photodiode signal is a weak signal , weak signal detection theory to the signal amplification process , designed to receive the signal processing circuit analysis using lock-in amplification principle . A monotone curve fitting data obtained by sampling a lot of analysis to obtain the moisture ratio , thereby informed of the values ??of the measured moisture of the paper . To meet the optical design of the performance indicators premise , it is necessary to simplify the design of the optical path , and the relative performance of the circuit , but also greatly reduces the cost . The method of this instrument can not only be applied to the field of moisture measurement , as long as the absorption spectra of the other ingredients of the substance found , the application of modern spectral detection technology will be able to detect other components , this is to study the potential significance of this issue .
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