Hydrogen sulphide detection using near-infrared diode laser and compact dense-pattern multipass cell*

Abstract

Sub-ppmv level detection of hydrogen sulphide (H2S) using a 1.578- μ m distributed feedback tunable diode laser combining with wavelength modulation spectroscopy and second harmonic detection scheme is reported. A home-developed novel compact dense-pattern multipass gas cell with an effective optical path length of 29.37 m is used to improve sensitivity and reduce sample volume. Detection parameters are optimized, including modulation frequency and amplitude. The analysis of Allan variance shows that a minimum detectable concentration 60 ppbv is obtained with a lock-in time constant of 10 ms, and a detection limit of 13 ppbv can be achieved by average in 300 s. The demonstrated H2S sensor has a strong penitential application in natural gas process for regulating and controlling H2S concentration.

All-optical light-induced thermoacoustic spectroscopy for remote and non-contact gas sensing

“…H 2 S as a toxic and corrosive gas was chosen as the analyte due to the widely detection demand in environmental monitoring, chemical production and power industry [44] , [45] , [46] , [47] , [48] , [49] , [50] . Fig.…”

Research on the enhancement of signal‐to‐noise ratio by radio frequency white noise in compact dense‐pattern multipass cell for trace gas detection

“…In recent years, laser absorption spectroscopy technology with its advantages such as high sensitivity, high accuracy, high selectivity, and short response time, has been widely used in environmental pollution monitoring, breathing gas composition analysis and industrial process optimization control, and so on. [1][2][3][4][5][6][7][8][9] At present, more widely used technologies include tunable diode laser absorption spectroscopy (TDLAS), cavity enhanced absorption spectroscopy, cavity ring-down spectroscopy, and photoacoustic spectroscopy. [10][11][12][13][14][15][16][17][18][19] In the TDLAS, the optical multipass absorption cell is one of the key equipment.…”

Miniature multi‐pass cell design with high path‐to‐volume ratio based on trough reflector

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] It is commonly combined with optical multi-pass cell (MPC) to increase the effective optical path length (OPL). [17][18][19][20] Nowadays, unmanned aerial vehicle (UAV) detection, 21,22 and automobile loading have been demanded due to their convenience and versatility. Therefore, developing the miniaturized and portable MPC is necessary.…”

“…Laser absorption spectroscopy based on Lambert–Beer law has been widely applied to trace gas concentration detection for air quality assessment, exhaled breath diagnosis and industrial emission monitoring 1–16 . It is commonly combined with optical multi‐pass cell (MPC) to increase the effective optical path length (OPL) 17–20 . Nowadays, unmanned aerial vehicle (UAV) detection, 21,22 and automobile loading have been demanded due to their convenience and versatility.…”