Fire Detector With a Scattered Light Arrangement

The present disclosure relates to fire detectors. Teachings thereof may be embodied in an optical smoke detector. For example, a fire detector may include: a housing with a smoke inlet opening; a detection unit for detection of specific fire parameters; an analyzing unit for output of a fire alarm; a light transmitter; and a light receiver connected to the analyzing unit for monitoring the smoke inlet opening for impermissible pollution. The light transmitter and the light receiver comprise a scattered light arrangement with a scattered light volume in a region of the smoke inlet opening susceptible to pollution. The light transmitter may be oriented so a part of the light bundle traverses the region without striking adjacent housing parts, or a part of the light bundle strikes a housing part and a surface of the housing part deflects the second part of the light bundle away from the light receiver or absorbs the second part of the light bundle. The analyzing unit sends a service message if the scattered light detected by the light receiver exceeds a threshold value.