BROAD-BAND ABSORPTION-COEFFICIENT MEASUREMENT ON METHANE USING SHOCK-TUBE

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