5.1 This practice gives an objective measure of the temperature sensitivity of a thermal imaging system (relative to a standard reference filter) exclusive of a monitor, with emphasis on the detector(s) and preamplifier.

Note 1: Test values obtained under idealized laboratory conditions may or may not correlate directly with service performance.

5.2 This practice affords a convenient means for periodically monitoring the performance of a given thermal imaging system.

5.3 NETD relates to minimum resolvable temperature difference as described in Practice E1213. Thus, an increase in NETD may be manifest as a loss of detail in imagery.

5.4 Intercomparisons based solely on NETD figures may be misleading.

Note 2: NETD depends on various factors such as spectral bandwidth and background temperature.

1.1 This practice covers the determination of the noise equivalent temperature difference (NETD; NEΔT) of thermal imaging systems of the conventional forward-looking infrared (FLIR) or other types that utilize an optical-mechanical scanner; it does not include charge-coupled devices or pyroelectric vidicons.

1.2 Parts of this practice have been formulated under the assumption of a photonic detector(s) at a standard background temperature of 295°K (22°C). Besides nonuniformity, examinations made at other background temperatures may result in impairment of precision and bias.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.