JPS5548637A - Photoacoustic detector - Google Patents

Abstract

PURPOSE:To facilitate an easy handling for the photoacoustic detector by providing the thermal flowmeter type detection element at the linkage part between the sample room and the reference room and then irradiating the optical energy to the sample through the light transmission window in order to detect the quantity converted into the thermal energy in the form of the thermal expansion of the gas around the sample. CONSTITUTION:The monochrome beams featuring the same wavelength and the energy are irradiated simultaneously to samples 2 and 20 distributed in sample rooms 1 and 10 through light transmission windows 3 and 30 to be absorbed into samples 2 and 20, and then the pressure of the gas in rooms 1 and 10 rise by the converted thermal energy. While the pressure in reference rooms 6 and 60 has no change, and thus the gas flows toward rooms 1 and 10 from rooms 6 and 60 to have vibrations via paths 7 and 70 and with the same cycle as the intermittent cycle of light intermittent chopper 15. These vibrations are detected in the form of the AC electric signals via thermal flowmeter type detection elements 8 and 80 provided at paths 7 and 70, and then the output signals of elements 8 and 80 are compared with each other to carry out the operational process.