Broadband absorption-coefficient measurement on methane using shock tube

Abstract

A new absorption method for probing infrared (i.r.)-active gases in shock tubes is discussed. An i.r. spectrograph is intended for the time-resolved i.r. (2.7–4.5 μm) spectral photography. The probing laser radiation, after passing through the shock tube, is converted into visible radiation by means of a kalium-titanil-phosphate non-linear optical crystal. This method allows using an optical multichannel analyser of visible wavelength radiation for sensing i.r. radiation. The i.r. spectrograph has been calibrated using the absorption of the 3.39 μm radiation from HeNe laser by methane.