Fluke Ti20 User Manual page 56

Ti20
Users Manual
Stare
A saturation effect caused by aiming a sensor at a hot target for an extended period of
time and then quickly aiming at a target at a lower temperature. The increase in time
(beyond the normal system response) for the sensor to return to within 5 % of the lower
temperature is defined as the stare time.
Storage Temperature Range
Ambient temperature range that the thermometer can safely withstand in a non-operating
mode, and subsequently, operate with-in published performance specifications.
Target
The object upon which the temperature determination is being made.
Temperature
A degree of hotness or coldness of an object measurable by a specific scale; where heat is
defined as thermal energy in transit, and flows from objects of higher temperature to
objects of lower temperature.
Temperature Coefficient (or Ambient Derating)
An indication of the instruments ability to maintain accuracy when the ambient
conditions are subject to a slow change or drift. The temperature coefficient is usually
expressed as the percent change in accuracy per degree change in ambient temperature.
For a rapid change in ambient conditions refer to Thermal Shock.
Temperature Resolution
The minimum simulated or actual change in target temperature that gives a usable change
in output and/or indication (per the ASTM standard test method E 1256-88).
Thermal Shock
A short-term error in accuracy caused by a transient ambient temperature change. The
instrument recovers from its accuracy error when it comes back into equilibrium with the
new ambient conditions.
Time Constant
The time it takes for a sensing element to respond to 63.2% of a step change at the target.
Transfer Standard
A precision radiometric measurement instrument with NIST traceable calibration in the
USA (with other recognized standards available for international customers) used to
calibrate radiation reference sources.
Transmittance
The ratio of IR radiant energy transmitted through an object to the total IR energy
received by the object for any given spectral range; the sum of emittance, reflectance, and
transmittance is unity.
A-6