Highly Responsive, Miniaturized Methane Telemetry Sensor Based on Open-Path TDLAS

Abstract

This paper proposes the design of a highly responsive, compact, non-contact methane telemetry sensor, employing the open-path tunable diode laser absorption spectroscopy (OP-TDLAS) technology. The sensor uses the dual-core structure of FPGA and ARM to achieve high-speed methane telemetry at 100 KHz repeated modulation frequency for the first time with a non-cooperate target, and a higher gas responsive time of 1.8 ms was achieved than previously reported. Moreover, the optical system (L × W × H: 68.8 × 52 × 62.7 mm) and the electronic system (L × W: 70 × 50 mm) make the sensor more compact. Methane gas samples of varying integral concentrations were examined at a distance of 20 m. The amplitude of the absorption peaks was subjected to a linear fit with the standard concentration values, resulting in a robust linear correlation coefficient (R2 = 0.998). Notably, despite the compact form factor of the methane sensor, it demonstrated commendable stability in gas concentration detection, offering a minimum detection limit of 43.14 ppm·m. Consequently, this highly responsive and compact methane sensor, with its open-path feature, is apt for integration into a variety of applications requiring such attributes. These include handheld telemetry devices, Unmanned Aerial Vehicle (UAV) gas detection systems, vehicle mounted gas detection, and laser gas radar.