Fixed Pattern Noise Correction; Target Mode - Teledyne FLIR A68 Series User Manual

Fixed Pattern Noise Correction

FLIR A68/A38 series cameras are factory calibrated to correct for fixed pattern noise.
The camera dynamically corrects the sensor response across the entire range of the
camera's ambient operating temperature using the factory calibration.
If the thermomechanical conditions of the camera differ significantly from the factory
calibration conditions, non-uniformities or unwanted artifacts may be seen in the
sensor response (for example, a halo or vignetting effect). This may be caused by the
environmental conditions or the particular camera installation (for example, how the
camera is mounted, the type of heat sinks, or airflows present, and so forth).
When using triggers in frame-on-demand mode, if the triggered acquisition is from a
cold start, the first few images might be of lower quality as the sensor heats up. In
addition, if external triggers are used to acquire images, the trigger frequency must be
stable enough so the sensor can maintain a constant temperature (when the camera is
in free running mode the camera temperature is constant).
However, if required, any remaining (or newly introduced) fixed pattern noise (FPN)
can be corrected by the user. FPN correction is performed exposing the camera on a
scene of uniform temperature and triggering the FPN calibration feature
(flatfieldCalibrationFPN).
The FLIR A68/A38 series allows users to perform a manual fixed pattern noise (FPN)
correction by providing the camera sensor a uniform scene using either:
• The camera's internal mechanical shutter
• User-defined external shutter
Note: FPN correction using the camera's internal mechanical shutter does
not compensate for some lens effects. For FPN correction to account for
lens effects, a manual correction must be performed by placing a suitable
external shutter target in front of the lens; refer to
FPN Correction With External Shutter

Target Mode

The FPN Target Mode (shutterTarget) feature specifies if the shutter is external or
internal.
38 • Features and Configuration Options
Performing Manual
for more information.
FLIR A68/A38 Series IR Camera User's Manual