Thin-Film Thermopile Matrix for Detecting Pulsed Radiation

A thin-film thermopile matrix is vacuum deposited on a glass substrate. Nickel and copper thin films are used for the two junction materials. A total of 400 junctions are deposited over an area 2.2 cm by 2.2 cm, corresponding to a junction density of 82 junctions/cm2. Half of these junctions are hot junctions and the other half are reference junctions. The reference junctions are shielded from the incoming pulsed radiation by a 0.05-cm-thick gold shield. All junction pairs are series connected so that the thermal emf´s add. An output voltage of 0.1 mV per junction pair is obtained when the device is illuminated with a 1.5-msec pulse from a l-kV xenon flash tube. The output voltage from an individually wired, Chromel-constantan thermopile is 0.2 mV per junction pair when the thermopile is illuminated with an identical pulse.