An Uncooled Microbolometer Infrared Imager With a Shutter-Based Successive-Approximation Calibration Loop

The size and power dissipation of an infrared imaging system can be reduced by the use of uncooled microbolometers; but the nonuniformity of the microbolometer makes such imaging systems heavily reliant on complicated calibration techniques, incurring an overhead which is particularly significant in low-cost, compact devices. We therefore propose a shutter-based successive-approximation calibration loop, which avoids the need to implement correction tables in software on an external processor. Prototype imager, consisting of an 80 × 82 pixel infrared focal-plane array and readout circuitry, has been implemented, and the experimental results confirm that our on-chip autocalibration approach compensates effectively for fixed pattern noise caused by the nonuniformity of the microbolometers.