This invention comprises a device for detecting and measuring a gas component of a gas mixture using the optical-pneumatic effect produced by absorption of infrared radiation by a gas. The device comprises, in optical alignment, a radiation source, filter means, a cuvette system and a receiver unit which contains a measuring chamber and a comparison chamber. Pressure differential means such as a diaphragm condenser measures the opticalpneumatic effect produced by the absorption of radiation. The device is provided with porous means for flow of gases to eliminate interfering fluctuations in gas flow.