GB528697A - Methods of and apparatus for sensing radiant energy - Google Patents

Abstract

528,697. Temperature-variable resistances. STANDARD TELEPHONES & CABLES, Ltd. May 12, 1939, No. 14227. Convention date, May 18, 1938. [Class 37] [Also in Group XL] A conductor is kept at a temperature below its " transition " temperature and adapted to be exposed to radiant heat or visible or invisible light which causes a rise of temperature producing a considerable change in the resistance of the conductor, the " transition " temperature being defined as the temperature at which the resistance of the conductors commences to fall rapidly towards zero. The change in resistance is utilized to perform various operations. As shown in Fig. 2, a strip 10 of tin or other suitable metal is mounted on a quartz plate 11 in a gastight vessel 12 connected by tubes 13, 14 to a ,refrigerating apparatus 15 adapted to circulate liquid or gaseous helium through the glass vessel, which is embraced by the poles 16, 17 of an electromagnet serving to adjust the " transition " temperature. An electric current is passed through the strip 10 from a battery 20 through a variable resistance 21 and a milliammeter 22, and the terminals 18, 19 of the strip are also connected to a vacuum-tube amplifier 23, whereby variations of resistance of the strip 10 when radiation falls on it, for example through a lens 24, are detected and utilized. In a modification, two additional strips are provided on the quartz plate, one on each side of the strip 10 and connected to the battery through separate variable resistances and milliammeters. In still another modification, Fig. 4, the conductor element 50 is arranged in the lower part of a vacuum jacketed vessel 51 within an outer vacuum jacketed vessel 57. Air is removed from the inside of the vessel 51 and replaced by gaseous helium in the lower half and liquid helium in the upper half.