28 • Features and Configuration Options Calibir 640 GigE IR Camera User's Manualthis can be useful, for example, when the camera is initially powered on and has yet to reachnormal operating temperature. The adaptive mode performs better if the camera has reached itsfinal operating temperature before FPN compensation is calibrated.Performing FPN CorrectionThe Calibir 640 Series allows users to perform a manual fixed pattern noise (FPN) correction.Cameras are factory calibrated across the full range of operating temperatures and dynamicallyadapt to the current camera ambient temperature. However, if the thermomechanical conditions ofthe camera differ significantly from the factory calibration conditions, non-uniformities or unwantedartifacts may be seen in the sensor response (for example, a halo or vignetting effect). This may becaused by the environmental conditions or the particular camera installation (for example, how thecamera is mounted, the type of heat sinks, or airflows present, and so forth).To correct for these anomalies, an FPN correction can be performed at the current operatingtemperature ( that is, a one-point correction). To do so:1. With the camera at current operating temperature, expose the camera (with the lens) to ascene of uniform temperature. For example, this can be done using an object with a flatsurface, ideally matte black and non-reflective, such as a metal plate. This flat surface mustnot be in direct contact with the camera lens to avoid heat transfer or reflection; leave asmall gap between the surface and the lens so they do not touch.Flat surface with uniform temperatureGap fromlensFigure 8: Performing FPN Correction2. Execute the calibration using the Calibrate FPN Compensation feature, available in theImage Processing category:
