Wuhan Guide IR136 Manual do Utilizador descarregar pdf (Página 65)

Thermografie in der Theorie und Praxis (INTERNET: www.irPOD.net / e-MAIL: [email protected] ) © Bernd Schindel 2007

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Amplifier

A device for increasing (multiplying) some characteristic of its input. In electronics, there are voltage and

current amplifiers that multiply the voltage (or current) of the input signal and output the amplified signal to

the next circuit stage.

A/D Converter, ADC, (Analog to Digital Converter)

A device for converting continuously changing input signals (analog) into discretely valued outputs (digital).

Antireflective Coating

A thin layer of material applied to the surface of an optical element to increase the transmission of the

element by reducing back scattering due to surface reflections. A simple A/R coating will be comprised of a

one-quarter wavelength thick coating of a material whose refractive index is between the indexes of the air

and the element material.

Aperture

A hole or opening limits the amount of radiation used by an optical system. The aperture of a system may

be set by the size of the lens or window bounding the cross section of the radiation bundle.

Apparent Temperature

The temperature determined for an object calculated by a remote infrared sensor based solely on the

amount of radiation it emits assuming the object has Blackbody emission characteristics.

Aspect Ratio

The ratio of the vertical length to the horizontal width. For a television display the aspect ratio is 3:4.

Atmospheric Window

Spectral radiation regions not absorbed by atmospheric gasses. These windows are transparent to

radiation at those wavelengths. The most obvious window is the visible light window - if the 'smog is not too

bad we can see through the atmosphere forever.

Atmospheric Attenuation, Atmospheric Absorption

The amount of signal reduction occurring when IR radiation travels through the atmosphere between the

target and imaging system. The amount of attenuation can be very small on clear days with short

transmission paths and can be very large on foggy, smoggy, dusty days with long transmission paths.

Attenuation

The reduction in intensity of radiation after processing through a filter. This can be measured in dB.

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Wuhan Guide IR136 Manual do Utilizador Página 65