TDLAS is an acronym for Tunable Diode Laser Absorption Spectroscopy, a technique for measuring the concentration of certain gases such as methane, water vapor and many more. By tuning the emission wavelength of a tunable laser, which can be a VCSEL, characteristic absorption lines of a gas on the path of the laser beam may cause a reduction of the measured signal intensity detected by a photodiode, which can be used to determine the gas concentration. Also the temperature and the pressure of the gas can be determined by analysis of the measured signal. R-phrases S-phrases , , , Flash point −188 °C Autoignition temperature 537 °C Explosive limits 5–15% Supplementary data page Structure and properties Thermodynamic data Spectral data UV, IR, NMR, MS Related compounds Related alkanes Ethane Propane Related compounds Methanol Chloromethane Except where noted otherwise, data are given for materials in... Water (from the Old English word wæter; c. ... Vapor (US English) or vapour (British English) is the gaseous state of matter. ... Diagram of a simple VCSEL structure. ... A photodiode A photodiode is an electronic component and a type of photodetector. ...