Pixel-wise real-time advanced calibration method for thermal infrared cameras

Abstract

Accurate radiometric calibration is a key feature of modern infrared cameras. Considering the newly available infrared focal plane arrays (FPA) exhibiting very high spatial resolution and faster readout speed, we developed a method to provide a dedicated radiometric calibration of every pixel. The novel approach is based on detected fluxes rather than detected counts as is customarily done. This approach features many advantages including the explicit management of the main parameter used to change the gain of the camera, namely the exposure time. The method not only handles the variation of detector spectral responsivity across the FPA pixels but also provides an efficient way to correct for the change of signal offset due to camera self-emission and detector dark current. The method is designed to require as few parameters as possible to enable a real-time implementation for megapixel-FPAs and for data throughputs larger than 100 Mpixels/s. Preliminary results with a high-speed 3 μm to 5 μm infrared camera demonstrate that the method is viable and yields small radiometric errors.