A Coin-Sized Oxygen Laser Sensor Based on Tunable Diode Laser Absorption Spectroscopy Combining a Toroidal Absorption Cell

Abstract

Laser gas sensors with small volume and light weight are in high demand in the aerospace industry. To address this, a coin-sized oxygen (O2) sensor has been successfully developed based on a small toroidal absorption cell design. The absorption cell integrates a vertical-cavity surface-emitting laser (VCSEL) and photodetector into a compact unit, measuring 90 × 40 × 20 mm and weighing 75.16 g. Tunable diode laser absorption spectroscopy (TDLAS) is used to obtain the O2 spectral line at 763 nm. For further improving the sensitivity and robustness of the sensor, wavelength modulation spectroscopy (WMS) is utilized for the measurement. The obtained linear correlation coefficient is 0.9994. Based on Allen variance analysis, the sensor achieves an impressive minimum detection limit of 0.06% for oxygen concentration at an integration time of 318 s. The pressure-dependent relationship has been validated by accounting for the pressure factor in data processing. To affirm its efficacy, the laser spectrometer underwent continuous atmospheric O2 measurement for 24 h, showcasing its stability and robustness. This development introduces a continuous online laser spectral sensor with potential applications in manned spaceflight scenarios.

A wide range oxygen sensing strategy with the collaboration of multiple phosphorescence probes

“…To overcome these limitations, optical methods with anti-interference properties have been proposed. Among these, the absorption spectroscopy method necessitates altering the length of optical path to measure various oxygen concentrations, which presented difficulties when designing portable instruments [9][10][11]. Measurement technology based on room-temperature phosphorescence (RTP) boasts the advantages of non-invasiveness and a compact probe design and exhibits resistance to electromagnetic interference [12][13][14][15].…”