RADIOMICROMETER
radiomicrometer
(noun) radiometer that is extremely sensitive
Source: WordNet® 3.1
Etymology
Noun
radiomicrometer (plural radiomicrometers)
a device used to measure small changes in radiant heat, or in temperature
Source: Wiktionary
Ra`di*o*mi*crom"e*ter, n. Etym: [Radio- + micrometer.] (Physics)
Definition: A very sensitive modification or application of the thermopile,
used for indicating minute changes of radiant heat, or temperature.
Source: Webster’s Unabridged Dictionary 1913 Edition