Archive > Volume 11 Issue 4 > 2015,11(4):298-302. DOI:10.1007/s11801-015-5102-2 CSTR:[cstr] Prev Next
A mid-infrared methane detection device based on dual- channel lock-in amplifier
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Abstract:
A portable dual-channel digital/analogue hybrid lock-in amplifier (LIA) is developed, and its amplitude detection error is less than 10% when the signal-to-noise ratio (SNR) is larger than −12 dB. Then, a differential mid-infrared methane (CH4) detection device is experimentally demonstrated based on a wideband incandescence wire-source and a multi-pass spherical reflector. The experiments are carried out to obtain the sensing performance of the device. With the absorption length of only ~4.8 cm, the limit of detection (LoD) is about 71.43 mg/m3, and the detection range is from 0 mg/m3 to 5.00×104 mg/m3. As the concentration gets larger than 714.30 mg/m3, the relative detection error falls into the range of −5%—+5%. Two seven-hour-measurements are done on the CH4 samples with concentrations of 1.43×103 mg/m3 and 4.29×103 mg/m3, respectively, and the results show that the maximum relative error is less than 5%. Because of the cost effective incandescence wire-source, the small-size and inexpensive dual-channel LIA, and the small-size absorption pool and reflector, the developed device shows potential applications of CH4 detection in coal mine production and environmental protection.
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This work has been supported by the National Natural Science Foundation of China (No.61307124), the Changchun Municipal Science and Technology Bureau (No.14KG022), and the Education Department of Jilin Province in China.
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