Research On Modulation Technology And Virtualization Of Optical Fiber Gas Sensor

At present, coal mine gas explosion severe, in order to accurately monitor the underground gas concentrations in real time, so safe and reliable, high sensitivity, high-precision gas sensor is particularly important. Optical fiber gas sensor detection sensors have unparalleled advantages over traditional, but for various reasons, there is a great distance away from the practical on existing detection devices, the paper hopes to contribute to this area.First, this paper analyzes the optical modulation technology, focused on analyzed the electro-optic modulation theory and techniques of the external modulation, and then focused on analyzed the widely used detection of gas concentration based on spectral absorption wavelength modulation; On these basis, analyzed the simple differential detection and the sensitive harmonic detection, then proposed a harmonic detection device based on wavelength modulation technology, and explained the device design requirements for various hardware and related parameters; Order to make accurate laser wavelength locking in the gas absorption line center, we design a digital PID controller for frequency stabilization; Meanwhile, the device uses software instead of hardware, computer-based platform called Virtual Instrument Software Labview data acquisition card driver, frequency stabilization using ActiveX technology called PID control MATLAB program, extract the first harmonic Programming, IIR digital signal filtering, data retention, and finally complete the monitoring interface design, to achieve a methane gas concentration data collection, preservation, processing and display alarm, and finally by experiment results reveal gas detection devices designed to effect a good frequency stabilization, high sensitivity, high reliability and high accuracy.This optical fiber gas detection device in various performance indicators could meet the practical requirements, in the future, to be Labview virtual instruments applied to embedded microprocessors, making the device further reduced, made a key step toward the practical on the device.Figure [46] Table [2] Reference [79]...