Pyroelectric detector

A Pyroelectric detector is an infrared sensitive optoelectronic component which are specifically used for detecting electromagnetic radiation in a wavelength range from (2 to 14) µm.

A receiver chip of a pyroelectric infrared detector manufactured by InfraTec consists of single-crystalline lithium tantalate. Because of its very high curie temperature of 620 °C lithium tantalate guarantees an extremely low temperature coefficient with an excellent long-term stability of the signal voltage.

Physical Basics of a pyroelectric detector

Pyroelectric detector from InfraTec

Unlike semiconductor detectors, a pyroelectric detector is a thermal detector working with a thermally isolated chip which is covered by a black absorption coating. This coating converts the infrared radiation falling on the chip to heat. The chip changes its temperature in the order of magnitude of µK … mK and, as a result of the pyroelectric effect, produces the electrical signal desired. Thermopiles, too, belong to the group of thermal detectors, however, the measuring effect is less significant. While pyroelectric infrared detectors show a good signal/noise ratio up to modulation frequencies of 4 kHz, e.g. in FTIR spectrometers, thermopiles produce good results up to modulation frequencies of specific Hertz only.

Pyroelectric detector with integrated beam splitter by InfraTec

In addition to the pyroelectric crystal, a pyroelectric infrared detector by InfraTec contains optical and micro-mechanical components. Two-channel and four-channel pyroelectric detectors with integrated beam splitter and integrated CMOS amplifier are micro-systems consisting of components which function thermally, electronically and optically.

As pyroelectricity is a characteristic of a subgroup of piezoelectric crystals, a pyroelectric detector reacts to airborne and solid-borne sound. This effect is often called microphony. However, a patented fastening of the pyroelectric chip by InfraTec reduces these negative effects for pyroelectric detectors dramatically so that in many cases these negative effects are in the order of magnitude of other interference voltage or of the inherent noise of the infrared detector only.