When is a NUC recommended?

• A. When HDIR image becomes degraded or shows fixed pattern noise or persistent bright/dark spots
• B. Only during rapid temperature changes
• C. Only after maintenance
• D. Only during daytime operations

Answer: (A)

The main idea is correcting the detector’s non-uniform response to restore a uniform image. NUC (Non-Uniformity Calibration) is used to compensate pixel-to-pixel variations in the infrared focal plane array so fixed-pattern noise and nonuniform brightness are removed, giving a clean image.

When is it recommended? When the HDIR image becomes degraded or shows fixed pattern noise or persistent bright/dark spots. Those symptoms indicate the detector’s response has drifted or becomes nonuniform, and a NUC will realign the pixel responses to improve image quality.

The other timings aren’t the trigger for a NUC. Rapid temperature changes, maintenance events, or daytime operations can influence image quality indirectly, but the decision to run NUC is driven by observed nonuniformities in the image, not by the time of day or a maintenance window.