PHOTO ACOUSTIC INFRARED (IR) DETECTOR

摘要

Photo acoustic infrared (IR) detector comprising a chamber (1) for receiving a gas or gas mixture, a window (6) for pulsed or modulated IR radiation (2) into the chamber, and a pressure sensor (3) adapted to measure pressure changes in the chamber (1) as a consequence of absorbed IR-radiation. A generally plate-shaped main part (5) has a recess or bore (5A) for substantially forming the chamber (1), whereby the window (6) closes the chamber (1) at one side of the main part (5), and whereby the pressure sensor (3) is of the miniature type and is located at the opposite side of the main part (5) in relation to said one side, so that the pressure sensor (3) communicates with and closes the chamber at the opposite side, except for a venting channel (9) for the chamber (1). A cap (7) is provided at said opposite side of the main part (5) so that it encloses the pressure sensor (3) and forms a gas space (10) communicating with the chamber (1) through the venting channel (9) and being substantially larger than the gas volume in thechamber (1).