Understanding Infrared Thermography Reading 3

Repeatability
Repeatability describes how faithfully a reading is repeated for the same
target over the short and long term. A typical specification would be, for
example, "repeatability (short and long term) of ±0.25 °C (±0.45ºF) “.
Temperature range and absolute accuracy will always be interrelated; for
example, the instrument might be expected to measure a range of
temperatures from 0 to 200 °C (32 to 392 OF) with an absolute accuracy ±2
°C (±3.6ºF) over the entire range. This could alternately be specified as ±1
percent absolute accuracy over full scale. On the other hand, the best
accuracy might be required at some specific temperature, say 100 °C
(212 ° F). In this case, the manufacturer should be informed and the
instrument could be calibrated to exactly match the manufacturer's laboratory
calibration standard at that temperature. Because absolute accuracy is based
on traceability to the NIST standard. it is difficult for a manufacturer to comply
with a tight specification for absolute accuracy. An absolute accuracy of ±0.5
°C (±0.9 ° F) or ±1 percent of full scale is about as tight as can be
reasonably specified. Repeatability, on the other hand, can be more easily
ensured by the manufacturer and is usually more important to the user.
Charlie Chong/ Fion Zhang