A Near-Infrared Trace CO2 Detection System Based on an 1,580 nm Tunable Diode Laser Using a Cascaded Integrator Comb (CIC) Filter-Assisted Wavelength Modulation Technique and a Digital Lock-in Amplifier

Abstract

A near-infrared trace CO 2 detection system was experimentally demonstrated based on an 1,580 nm distributed feedback (DFB) laser using a cascaded integrator comb (CIC) filter-assisted wavelength modulation spectroscopy (WMS) technique and a digital lock-in amplifier (DLIA). An 1,580 nm DFB laser emitting at 1,579.1 nm was selected as the light source. A multi-pass cell (MPGC with a 30 m-long path) was adopted as the absorption cell. A DLIA was developed to extract the second harmonic WMS (WMS-2f) signal. The cascade-integrated comb filter (CICF) and the finite impulse response (FIR) low-pass filter (LPF) were combined in the DLIA to improve the performance of DLIA. Three methods of PD (Peak detection), LIA, CICF-assisted WMS, and DLIA were adopted to detect the CO 2 concentration levels and the anti-interference performance of each detection method was analyzed. The experimental results indicated that compared with the peak detection and the lock-in amplifier method of the CICF-assisted WMS and DLIA developed in this manuscript had the highest linearity and precision. When the integration time is 3s, the LOD of the system was predicted to be 0.0812 ppm. Due to the advantages of high sensitivity, a low detection limit and a rapid response, the CO 2 detection system reported in this manuscript has a good application prospect in the area of oilfield associated gases detection.

A near‐infrared CO2 detection system for greenhouse gas based on PCA‐DNN

“…TDLAS is a rapidly developing spectroscopic measurement technique in recent years 7–10 . It uses the principle that laser energy is absorbed by gas molecules to develop an absorption spectrum to measure gas concentrations, and has good possibilities for development 11–14 …”

“…[7][8][9][10] It uses the principle that laser energy is absorbed by gas molecules to develop an absorption spectrum to measure gas concentrations, and has good possibilities for development. [11][12][13][14] In recent years, machine learning algorithms have been widely used in spectral analysis. 15 Goldenstein et al 16 proposed an algorithm to normalize high-order harmonic signals based on first-harmonic signals, and then make conditional least squares (CLS) predictions for the processed signals, and test them with an air-water vapor mixture.…”

Detection of NH3 in poultry housing based on tunable diode laser absorption spectroscopy combined with a micro circular absorption cell

“…Tunable diode laser absorption spectroscopy (TDLAS) uses a tunable distributed feedback (DFB) laser which has a narrow band wavelength corresponding to the gas absorption line to detect gas concentration specifically and sensitively. In recent years, TDLAS has been widely used to monitor harmful gases in industry [20][21][22]. However, existing commercial TDLAS sensors used for industrial gas monitoring usually have a high detection limit and large size with a heavy frontal absorption cell, which makes them unsuitable for high-precision, on-site measurement of trace ammonia in poultry houses.…”

Recent Advances in QEPAS and QEPTS Based Trace Gas Sensing: A Review

“…Due to the advantages of high selectivity and sensitivity, cost benefits, in-situ and non-invasiveness detection [1][2][3], optical gas sensors are widely used in numerous fields, such as combustion diagnostics, atmospheric monitoring, life sciences, planetary exploration, environmental monitoring, and early fire detection [4][5][6][7][8][9]. Many laser spectroscopy-based methods such as tunable diode laser absorption spectroscopy (TDLAS) [10][11][12][13][14][15], photoacoustic spectroscopy [16][17][18], and photothermal spectroscopy [19] have been adopted extensively.…”