Details of a fire detection system using the deflection of a laser beam
above a fire are described. It is shown that such a system will decrease
in sensitivity with the height of the compartment to be protected at a
lower rate than with point detection systems. Devices are described for
preventing false alarms due either to building disturbances or to
ambient variations in temperature.
It is claimed that such a system would have economic advantages over
other systems and that it could readily be adapted to give intruder
protection.
