Pyroelectric transducers

Fourier transform IR instruments contain no dispersing element, and all wavelengths are detected and measured simultaneously. Instead of a monochromator, an interferometer is used to produce interference patterns that contain the infrared spectral information. The. same types of sources used in dispersive instruments are used in FTIR spectrometers. Transducers are typically triglycine sulfate—a pyroelectric transducer—or mercury cadmium telluride—a photoconductive trans-... 

Pyroelectric transducers exhibit response limes thal are fast enough to allow them lo track the changes in the lime-domain signal from an interferometer. For Ihis reason, most Fourier transform infrared spectrometers use this type of transducer. 

IR transducers are of three general types (1) pyroelectric transducers. (2) photoconducting transducers, and (3) thermal transducers. The tirst Ls found in photometers, some FTIR spectrometers, and dispersive speclropholometers. Photoconducting transducers arc found in many F TIR inslrumonis. Thermal detectors arc found in older dispersive instruments but arc too slow to be used in FTIR spectrometers. 

Pyroelectric transducers are constructed from single crystalline wafers of pyroelectric materials, which are insulators (dielectric materials) with very special thermal and electrical properties. Triglycine sulfate (NH7CH2COOH), H. SOt (usually dcutcraicd or with a fraction of the glycines replaced with alanine), is the most important pyroelectric material used for IR-detcction systems. 

Pyroelectric transducers exhibit response (imes that arc fast enough to allow them U) track the changes... 

Piezo- and pyroelectric transducers for motion sensors, hydrophones, audio devices, etc supercapacitors (103) electrolytic capacitors (104) aircraft interior sound control... 

Simply put, a pyroelectric transducer is a piece of pyroelectric material placed between two electrodes. Pyroelectric material produces elechical polarization, such as in a crystal, via a change of temperature. The charge distribution on the pyroelectric material changes when it senses temperature variation. Therefore, the received IR at different intensities will produce electric signals that can be processed. 

If we consider a pyroelectric transducer, with thickness /p and surface area A, in a one-dimensional configuration, a change of the temperature distribution 6 x, t) relative to an initial reference situation G x, tg) will cause a change of polarization. This in turn induces an electric charge given by ... 

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