Patent attributes
A detector comprises a housing (1) having a window (3), a measuring and processing unit (2), a source (4) of electromagnetic radiation, a plurality of sensors (7), and a reflector (6). The measuring and processing unit (2), the electromagnetic radiation source (4) and the sensors (7) are mounted within the housing (1). The reflector (6) is mounted outside the housing (1). The reflector (6) is positioned to reflect electromagnetic radiation passing through the window (3) from the electromagnetic radiation source (4) onto the sensors (7) via the window. The sensors (7) are operatively associated with the measuring and processing unit (2) to provide that unit with an input indicative of the level of electromagnetic radiation reaching the sensors.
