A New Receiver of Radiant Energy

Describes a device to be actuated by impulses of radiant energy in the form of light or heat. The impulses may succeed each other with a frequency of one or more a second. Use is made of a finely divided gas occluding substance confined in a hermetically sealed chamber, one side of which is a thin metal diaphragm forming a portion of a condenser receiver. When light or heat falls upon this substance the gas within the chamber expands and changes the capacitance of the condenser receiver. When the device receives an impulse of radiation, it shows a sensitivity of more than 50 volts per watt per cm2.