Abstract: A pneumatic infrared radiation detector for intermittent irradiation with infrared light has a hermetically sealed chamber including a metal cup having a highly reflective inner surface forming the back of the chamber and a flange-like rim at the open end thereof. A radiation admitting window is disposed at the open end of the cup and a flow detector is connected to the chamber. The cup comprises a thin-walled noble metal vessel comprising one of gold and silver and the window is composed of at least one of calcium fluoride and barium fluoride and sealed vacuum tight to the cup with glass solder having a coefficient of expansion of between 110 and 150. 10.sup.-7 /K.

Abstract: A microrheoscopic detector for gases, especially for infrared gas analyzers comprises a base and a heating conductor mounted to the base. Two resistance thermometers are disposed in the area of influence of the heating conductor and comprise thin wire which is held between thicker connecting wires which are in turn affixed to the heating conductor.