The Non Uniformity Correction function is a mechanical shutter that closes between the detector and the lens in order to calculate "fine offset" values to ensure correct readings.
This function is an inherent part of a bolometer. If the NUC shutter is not operated, temperature readings will be out of specification and the image may be "noisier" that usual.
Causes for non-operation of the NUC shutter:
1. It is possible that this NUC shutter is not enabled in the ThermoView project.
2. There is a defect in the NUC shutter
3. The NUC shutter is disabled from automatic operation and relies on an external input to either inhibit or initiate - most often used for batch testing.
Example 1
You can check the ThermoView project settings via Camera Controls:
This generally is only applicable if symptoms have been present from day 1 or there has been some change in the project file.
Example 2
For installations where symptoms have presented after a period of normal operation and the project setting have not been modified the problem is likely with the NUC shutter itself. In this case, one might see an improvement by manually initiating the shutter once or more times. However, this may only be a temporary solution and the system behaviour will need to be closely monitored.
Example 3
The NUC shutter is actively disabled and set to run on some kind of external trigger or time trigger.
