Low level smoke emission measurements from a flame by photothermal deflection spectroscopy

Smoke emission measurement by conventional filtering techniques is inaccurate for low levels of smoke (below ~2 mg/M(3)). Here photothermal deflection spectroscopy (PDS) is used to measure low levels of smoke emitted from a diffusion flame. In the PDS smoke instrument, an argon-ion laser heats the smoke sample and the deflection of a He-Ne laser probe beam is detected by a position sensor. The beam deflection is directly related to the smoke density. Using PDS, smoke emissions from an acetylene flame are detected at levels as low as 50 microg/m(3) (5 x 10(-6) cm(-1) light absorption).