The output of FLIR’s OEM cameras typically varies from pixel to pixel and over the operational temperature range of the sensor. The output of OEM cameras is corrected for temperature-dependent non-uniformity, as well as for gain, by means of a calibration process. For most OEM camera configurations, this correction is applied over an operational temperature range of -40 °C to 80 °C.
FLIR calibrates thermal cameras by collecting data from the sensor while looking at two different blackbody sources, and while alternating the sensor from a temperature of -40° C to 80 °C *. Non-uniformity compensation or NUC coefficients (pixel gain and offset terms) are created over this entire range, then stored in camera memory and applied to the digital output upon operation.
Tau2 and Quark2 are configured with internal temperature sensors to monitor camera temperature while operating. During the factory calibration process, four non-uniformity compensation (NUC) tables are created and stored in every camera. “NUC 1, NUC 2, NUC 3, and NUC 4” are the calibration tables used.NUC Table boundaries for Tau2 and Quark2 as of 2015:
|NUC1||-40 °C to -20 °C|
|NUC2||-20 °C to +25 °C|
|NUC3||+25 °C to +65 °C|
|NUC4||+65 °C to +80 °C|
These NUC tables are used based on the operational temperature of the camera itself. Tau2 and Quark2 cameras incorporate control logic to switch from table to table based on the temperature of the internal sensor. Muon has all four tables, but relies on the host (furnished by the system integrator) to provide the control logic to switch between appropriate tables depending on sensor temperature.*Note that Commercial or C-grade Tau2 cameras have a different operating temperature range specification, and therefore use NUC tables 2 and 3, only.