LASERS IN ENGINEERING, vol.51, no.1-5, pp.205-215, 2021 (SCI-Expanded)
We design a new ultra-sensitive optical methane sensor by combining such optical approaches as appropriate use of absorption bands of methane by HITRAN database in the near-infrared (NIR) region, effective absorption path length in circular multi-pass optical cell, a wavelength modulation, and noise suppression with dual beam configuration. The design offers a compact and portable optical sensor for methane gas measurements in real time and high sensitivity. In the design, one can select different laser diode source to expand the selectivity labels for the interest many other trace gases. This is inexpensive and simpler experimental design without complexity of laser frequency locking and phase stabilization. It can find wide applications in many fields such as physical, environmental, and atmospheric research as well as physics, analytical chemistry, biology, medical diagnosis and process technology.