FLIR use a comprehensive FFC process in their cameras which may explain the time taken to complete the event.
We have to remember that FLIR are in the business of producing thermal cameras that meet, or exceed their claimed specification. That is why they are one of the big names in the field of thermography. Radiometric measurement accuracy is often the higher priority, rather than ‘pretty pictures’ or uninterrupted imaging.
An FFC event is part of the microbolometer imaging process where accurate temperature measurements are required. The FFC flag not only provides a flat field to level the pixels but it also provides a temperature reference against which to calibrate measurements. It is possible to operate a Microbolometer based thermal imaging system without an FFC event routine but measurement accuracy suffers and some minor variance in pixel outputs when viewing a flat scene is to be expected. Operating in a non FFC event mode is often required for videography where pretty pictures take priority over measurement accuracy. Image processing algorithms provide dynamic ‘virtual’ FFC to maintain an acceptable image quality. The latest microbolometers do not tend to use Peltier temperature stabilisation due to its inherent high power consumption and vacuum contamination issues. Peltier module equipped temperature stabilised microbolometers would cope better without the FFC event than the latest non temperature stabilised microbolometers but the Virtual FFC algorithm does its best in the circumstances.
If a user demands the best possible thermal imaging without interruption, such as required for wildlife videography for broadcast, then a cooled thermal imaging camera may be used as this does not require an FFC event due to its inherent temperature stability. As has been stated, the BST based cameras used a rotating chopper wheel that levelled the sensors view after each frame was read out so no FFC event was visible to the user. BST was not well suited to radiometric measurements however. That may have changed if development of the technology had been continued. A sad loss to the thermal imaging community.
To professional users of Microbolomter based thermal imaging cameras, the FFC event is expected and tolerated. Sure they would prefer to not have the short break in imaging every 2 minutes or so, but they often need the measurement accuracy that the FFC event helps to achieve. In consumer circles where the public are used to high quality imaging from camcorders and phones etc, the FFC event can appear to be an awful imposition on their viewing pleasure. That is because they do not understand the amazing technology that is at work to provide them with affordable thermal imaging. Such is life and FLIR will not lose any sleep over it.
The following link takes you to the FLIR FFC process patent that explains the process and may help the reader to understand what actually happens while the FFC event is taking place. It is not as simple as might first be thought
https://patentimages.storage.googleapis.com/ba/c9/a6/94221fac22ca2f/US8373757.pdfFraser
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