Fluke Ti20 User Manual page 53

Appendices
A
Glossary
Field of View (FOV)
The region, at the target, measured by the IR thermometer. Typically presented by giving
the spot diameter as a function of distance from the instrument. Also presented as the
angular size of the spot at the focus point.
See Optical Resolution.
Focus Point (or Distance)
The distance from the instrument where the optical resolution is greatest.
Full Scale
The maximum of the temperature range or output signal.
Full Scale Accuracy
A convention for expressing the accuracy as percentage of an instrument's (highest) full-
scale temperature.
Gray Body
A radiating object whose emissivity is in constant ratio (not unity) at all wavelengths to
that of a blackbody at the same temperature, and does not transmit infrared energy.
HAL
High Alarm. Units with this feature can sound an alarm when they sense that a user-
defined high temperature has been reached.
Hertz (Hz)
Units in which frequency is expressed. Synonymous with cycles per second.
Infrared (IR)
The portion of the electromagnetic spectrum extending from the far red visible at
approximately 0.75 µm, out to 1000 µm. However, because of instrument design
considerations and the atmospheric windows, most infrared measurements are made
between 0.75 µm and 20 µm.
Infrared Thermometer
An instrument that converts incoming IR radiation from a spot on a target surface to a
measurement value that can be related to the temperature of that spot.
LAL
Low Alarm. Units with this feature can sound an alarm when they sense that a user-
defined low temperature has been reached.
Laser
Single or dual lasers are used in some units for aiming and/or locating the optimum
temperature measurement point.
A-3