Transducers infrared

Thermal Transducers Infrared radiation generally does not have sufficient energy to produce a measurable current when using a photon transducer. A thermal transducer, therefore, is used for infrared spectroscopy. The absorption of infrared photons by a thermal transducer increases its temperature, changing one or more of its characteristic properties. The pneumatic transducer, for example. 

The class of ferroelectric materials have a lot of useful properties. High dielectric coefficients over a wide temperature and frequency range are used as dielectrics in integrated or in smd (surface mounted device) capacitors. The large piezoelectric effect is applied in a variety of electromechanical sensors, actuators and transducers. Infrared sensors need a high pyroelectric coefficient which is available with this class of materials. Tunable thermistor properties in semiconducting ferroelectrics are used in ptcr (positive temperature coefficient... 

Some proportional detectors are combined in the same instrument with a suitable transducer which can perform some of the functions of a controller. For example, for pneumatic systems the primary sensing element actuates a variable air jet, thus modulating an air pressure which is transmitted to a further controller or direct to the controlled device. Electric and electronic detectors such as the infrared detector include the sensing and amplifying circuits of the instrument. 

Applications of infrared sensors have been reported in the fields of biology/biochemistry, medical diagnostics, environmental monitoring and process control. IR sensors can measure analytes in solid, liquid or gaseous form using one of several different transducer layouts. 

U. Milnch, D. Jaeggi, N. Schneeberger, A. Schaufelbuhl, O. Paid, H. Baltes, and J. Jasper. Industrial fabrication technology for CMOS infrared sensor arrays , Dig. Tech. Papers Transducers 97, Vol. 1, Chicago, IL, USA, (1997), 205-208. 

The first commercial non-contact extensometers were optical extensometers which used either visible or infrared light to illuminate targets on the test piece. The essential difference between the optical and contact types is in the method of following the extension as illustrated in Figure 8.12, thereafter they both use some form of transducer to measure the movement which largely dictates the range and sensitivity. 

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-... 

A photon detector produces a current or voltage as a result of the emission of electrons from a photosensitive surface when struck by photons. A heat detector consists of a darkened surface to absorb infrared radiation and produce a temperature increase. A thermal transducer produces an electrical signal whose magnitude is related to the temperature and thus the intensity of the infrared radiation. 

If the infrared radiation from an emitting body can be captured and transduced into a usable signal, it can be made the basis for measuring the temperature of the emitting surface. Such a method is particularly attractive for the measurement of the temperature at a rubbing interface, since it does not require the insertion of a probe which might introduce a major perturbation into the system. However the method does require that the behavior of the system obeys the Stefan-Boltzmann relation... 

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