Design and Analysis of a Single Humidity Sensor Based on TDLAS for Water Vapor and Heavy Oxygen Water Vapor Detection

In this paper, a single humidity sensor for water vapor and heavy oxygen water vapor detection is presented. The sensor is based on tunable diode laser absorption spectroscopy (TDLAS) and thus has high sensitivity, good selectivity, and a short response time. A 1372 nm distributed feedback (DFB) diode laser is utilized as the light source, the wavelength tuning range of which covers the absorption lines of water vapor and heavy oxygen water vapor. A Herriott gas cell with 12 m optical length is designed for signal-to-noise ratio (SNR) enhancement. The sensor can distinguish between water vapor and heavy oxygen water vapor effectively. The accuracy of water detection is within ±0.5% RH. The accuracy of heavy oxygen water vapor detection is within ±1.0% RH.