Optical smoke detector using light dispersion - has receiver providing signal representing received light polarised perpendicular to plane containing axes of source and receiver

摘要

The smoke detector has a closed measuring chamber (1) containing a radiation source (5) and a corresponding receiver (7) providing an output signal representing the detected dispersed light which is polarised perpendicular to the plane containing the axes of the source and the receiver. A polarisation filter is contained in the measuring chamber between the source and the receiver for transmission of the light with the required polarisation or the light source is provided by a laser diode providing the polarised light. ADVANTAGE - Improved detection sensitivity for open blaze without effecting response for smouldering fire.