BRIDGE DEVICE FOR MEASURING THE INFRARED RADIATION

A bridge device for measuring infrared radiation comprises a pair of branches, one of which serially includes a thermistor bolometer and a D.C. voltage source, and the other of which serially includes a resistor and a D.C. voltage source. The thermistor bolometer is located so as to be illuminated by the radiation of the infrared rays being measured as the same are passed through an opening of a rotary sector. Means are provided for periodically applying high voltage pulses respectively to the branches of the bridge circuit in order to momentarily increase the voltage levels of the D.C. voltage sources during the period that the radiation from the incident infrared rays being measured falls on the thermistor bolometer. A synchronous rectifier, which operates in a synchronized relation with the aforesaid pulses, is provided for producing an unbalanced voltage between the branches of the bridge, the same being an indication of the infrared rays being measured.