Muon’s output is fully corrected for temperature-dependent non-uniformity and for gain over an operational temperature range of -40 C to 80 C. Normally a LWIR bolometer’s output will be variable pixel to pixel and over the operational temperature range of the sensor. For example, a pixel may read 7000 counts at room temperature and 7200 counts at a different temperature (14-bit scale equals 0 to 16383). Calibration involves 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. Correction coefficients are created over this entire range and stored in the Muon’s flash memory and applied to the digital output upon operation.
Muon has an internal temperature sensor such that it is able to know the temperature while operating. Four calibration tables are created for each unique Muon and those tables can be used based on the operational temperature of the Muon itself. However, the Muon does not have any control logic to switch from table to table based on the temperature of the sensor. The host imaging hardware should interrogate the sensor temperature (either I2C or telemetry data) and place the Muon in the correct calibration table. “NUC 1, NUC 2, NUC 3, and NUC 4” are the calibration tables used. The user should ensure “BOLO” and “GAIN” are enabled on their Muon and then operate in the correspondingly correct NUC table based on the Muon temperature sensor. By enabling “BOLO” and “GAIN” the user enables the calibration terms stored on the Muon itself. Per-pixel “GAIN” has been separated from “BOLO” for those customers that will use the Muon in radiometric applications and have a video pipeline necessitating them separate. See eIDD for more detail.
The complicated process of calibration can be time consuming and involve expensive hardware and technician time. FLIR calibrates Muon in many hundreds at a time along with its automotive production sensor line to ensure the best calibration possible at the lowest cost. A calibrated core, such as Muon, is far more cost effective as a solution as compared to a sensor-only product that the customer then has to calibrate themselves.