Design And Implementation Of Infrared Gas Sensors

This paper designed a kind of the combustible gas sensor based on infrared absorption principle,uses electric modulation non-dispersive infrared technology,because most of the combustible gas have absorption peak at about 3.40 microns wavelengths,so selection filter center wavelength of 3.40 microns to detecting combustible gas,the filter of the corresponding output signals called measure signals,to guarantee the reliability of the sensor measurement value and long-term stability,then choose a filter as the reference signal,because most of the gas at about 4.00 microns no absorption,so the second filter center wavelength is 4.00 microns,the second filter of the corresponding output signal is the reference signal.Due to the reference signal is stable in theory,so when the sensor hardware system appeared the phenomenon such as aging,drift,measuring signal changes,the reference signal can be the basic rule out such anomalies.Sensor selects the ARM microprocessor as the control of the whole system of the kernel and computing unit,ARM processor used to own a timer interrupt signal,each time interrupt driven infrared light source transformation work status,so as to realize the infrared light source modulation.Electric modulation infrared light source through the gas chamber to reach the pyroelectric detector with filter,pyroelectric detector output electrical signal,the electrical signal after amplification filter processing by the ARM processor to start the A / D conversion Digital signal processing algorithm to denoise and filter digital,real-time measurement data and calibration data calculated according to the formula,you can get real-time measurement of gas concentration value.After a large number of experiments,the sensor measurements accurate,reliable,responsive,small size,low power consumption,resolution 0.01% VOL,test data and performance indicators to achieve.