Wuhan Guide IR136 Manuel d'utilisateur télécharger pdf (Page 71)

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

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Evacuate

To empty. Used in relation to cleaning Dewars or cylinders prior to refilling them with pure gas. Cylinder

evacuation is usually done by drawing a vacuum with a vacuum pump and mildly heating the cylinder to

expedite the evacuation. Pure evacuation cleaning can take up to two days of continuous vacuum so an

alternating cycle of purging and evacuating the container is recommended.

Exfiltration

Air flow out of a building structure. To measure exfiltration, a blower door is attached to the structure and

the interior is pressurized and accurate measure is made of the exfiltration rate and areas of leakage.

Exothermic

Pertaining to heat generation. A chemical reaction is exothermic if it liberates heat as the reaction

proceeds.

F-Number(f/#)

The ratio of focal length to aperture for a lens assembly.

Fahrenheit

A temperature measurement scale which defines the ice point of water as 32 degrees F and the boiling

point of water as 212 degrees F. Absolute zero is -459.7 degrees F.

Far Infrared (LWIR)

Infrared radiation whose wavelength is in the range from 8 to 100 microns.

Field of View(FOV)

The total field measured in angle within which objects can be imaged or measured and displayed by an

infrared system.

Filter (Optical)

An optical device which modifies the characteristics of radiation which is passed through it. Usually filters

either attenuate all wavelengths of radiation a certain controlled amount or modify the optical pass band of

the radiation - eliminating selected wavelengths or bands while allowing others to pass.

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Wuhan Guide IR136 Manuel d'utilisateur Page 71