Lasers for Gas Sensing

OPO-based PAS provides ultimately fast and sensitive trace gas analysis

The photoacoustic infrared spectroscopy (PAS) is a very promising technology for trace gas detection and analysis in environmental or atmospheric monitoring, industrial process control or medical diagnostics. PAS is based on exciting rotational and vibrational states of gas-molecules with infra-red light pulses.

The absorbed energy translates into kinetic energy pulses, which form an acoustic wave that can be detected with a microphone. In this way PAS can provide a sensitive and selective, compact and robust, multi-gas analyzer with wide dynamic range and fast response time. Recent development in technologies for MEMS fabricated cantilever microphones with optical laser readout combined with availability of new monochromatic and tunable mid-IR light sources with high output powers has enabled demonstration of PAS instruments with ppb-level sensitivity and very broad selectivity.