Improved MWIR reference sources for FPA non-uniformity correction
2010
We have previously discussed the potential of using an Hg1-xCdxTe (MCT) source as a reference plane for the nonuniformity
correction of thermal imagers. Due to the fast switching speed, the apparent temperature can be changed on a
frame to frame basis. This allows multipoint correction data to be obtained without having to wait for temperatures to
stabilize as with a Peltier reference source. Also, the operation of the device can be synchronized to the integration
period of the camera to reduce the mean power requirements by the ratio of the frame to the integration time and hence
thermal heating effects are also reduced.
In this paper, we discuss a practical implementation of this concept in a thermal imaging camera, which is being
developed as part of the UK MOD Albion program. This development has involved increasing the device size,
increasing the effective temperature range and matching the drive requirements to typical camera power supplies. The
factors determining the achievable effective temperatures are discussed, together with modifications to the device design
that have been implemented to obtain a useful temperature range. The drive requirements have been improved by
developing a series connected structure. This has reduced the peak current by a factor of 4 and allows the devices to be
controlled with conventional Peltier reference electronics rather than a custom unit. The improved devices have now
been incorporated into a state-of-the-art infrared camera and their performance in this system will be discussed.
Keywords:
- Correction
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