(under subclass 213) Subject matter including a movable mechanical element having areas or volumes of different heat absorbing characteristic, the element being moved by the infringing radiation producing a temperature differential in the respective areas or volumes, as by the gas adjacent the warmer area or volume producing greater pressure thereon.
SEE OR SEARCH CLASS
250, Radiant Energy,
472.1+, for invisible radiation responsive nonelectric signalling devices.
340, Communications: Electrical,
189+, where this phenomenon is used to transmit signals such as messages; subclasses 540+ to note conditions other than measurement of the intensity of light, particularly subclass 592.
374, Thermal Measuring and Testing, 121+, for radiometer type devices for measuring the temperature of hot bodies by measuring the heat radiation therefrom.
