ABSTRACT
The thermocouple was discovered in 1826 by the Russian-born German physi cist, J. Seebeck. He discovered that at the junction of two dissimilar conductors a voltage could be generated by a change in temperature (see Figure 4.1). Using this effect Melloni1 produced the first thermopile detector in 1833, to investigate the infrared spectrum. The thermopile is one of the oldest IR detector, and is a collection of thermocouples connected in series in order to achieve better tem perature sensitivity.
