BASF EXACTUS, Руководство пользователя

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7 Glossary of Terms
Accuracy
How well the measurements agree with standards. In temperature measurement,
this is usually the agreement between the International Temperature Scale ITS-
90 and the instrument. However in practice, it is usually the agreement between
the instrument and whatever the manufacturer is using to calibrate the
instrument. BASF uses the freeze points of pure metals, ITS-90 fixed
temperature points, to calibrate its instruments. (See also
Freeze Point
Furnaces
).
Analog
Output
BASF offers an analog output module. The module takes the high speed digital
probe signal and converts it to an analog signal which is linear with respect to
measured temperature. The module is configured for either 0 to 10 volts or 0 to
20mA. This output can be scaled through the TemperaSure
software. (See
section 4.7 and Appendix 3 for configuration details.)
Bandwidth The response time of the electronics (also see Speed ).
Blackbody
A theoretical object that emits light perfectly, also known as “ the perfect
emitter ”. By definition, a blackbody has an emissivity of exactly one (1.0). A
blackbody emits light solely as a function of its own temperature. The amount
of light absorbed
α α α α equals the amount emitted ε εε ε for steady state (no change in
temperature). An ideal blackbody absorbs 100% of the light impinging on it.
(Also see
Kirchhoff and Planck ).
Emissivity The measure of how well an object emits light compared to a perfect
blackbody. A blackbody has an emissivity of 1.0, and everything else, both real
and theoretical, has an emissivity less than 1.0. Aluminum has a low emissivity
because it only emits a small percentage of the amount of light that a blackbody
would emit at the same temperature. Emissivity has many aspects because real
objects emit light in very complex ways.
There are numerous parameters that define an object’s emissivity in terms of
how the light is emitted, including angle, wavelength, surface texture, thin films
on the object, surfaces surroundings the object, material(s) that make up the
object, and the object’s own temperature. Using shorter wavelengths reduce
these measurement errors as can be seen in the following graph.
Cross Section of a Blackbody Cavity
ε = α ε = α ε = α ε = α