thermopile vs. thermocouple

a device consisting of a number of thermocouples joined in series, used for generating thermoelectric current or for detecting and measuring radiant energy, as from a star.

a device that consists of the junction of two dissimilar metallic conductors, as copper and iron, in which an electromotive force is induced when the conductors are maintained at different temperatures, the force being related to the temperature difference: used to determine the temperature of a third substance by connecting it to the junction of the metals and measuring the electromotive force produced.