Optical Generation and Detection of Acoustic Pulse Profiles in Gases for Novel Ultrasonic Absorption Spectroscopy

摘要

We demonstrate a new all-optical, frequency-multiplexed and fast technique for gas-phase ultrasonic absorption spectroscopy. A pulsed laser produces a short-duration acoustic pulse in the gas sample, and the acoustic pulse profiles at two distances are monitored by focused continuous probe beams. Fourier decompositions of these probe deflection signals provide the absorption spectrum, and examples for CO2 + H2O mixture are given. Ultrasonic propagation speeds in the MHz regime are also obtained for several gases.