A $10 thermal infrared imager

Abstract

A thermal infrared imager of competitive sensitivity and very simple construction is presented. It is a pyroelectric device of 96 pixels, based on ferroelectric polyvinylidene fluoride (PVDF). It uses a novel charge-dispensing multiplexer based on ordinary light emitting diodes to achieve a noise-equivalent temperature change (NEΔT) of 0.13 K at a 5 Hz frame rate (2.1 Hz BW). Design information, theory, and measured performance are presented. Achieving such a low total system cost requires the use of the very least expensive optical system, a moulded polyethylene Fresnel lens, whose advantages and limitations are discussed. Several possible improvements, aggregating approximately 30 dB in sensitivity are also discussed, leading to the interesting possibility of few-millikelvin NEΔT values with an uncooled pyroelectric device of extremely low cost.