Extension of the Dynamic Range of Short-Wavelength IR FPAs

Abstract

Necessity of extension of the dynamic range of short-wavelength IR FPAs is substantiated. Conventional methods exhibit low efficiency, especially, in large-scale arrays with a pitch of no greater 15 μm. Integrating cells with individually tunable transfer function depending on the fragment brightness have the maximum efficiency with respect to the extension of the dynamic range (up to 100 dB). A simple (in topological implementation) and efficient method is proposed for extension of the dynamic range. The method is based on the individual self-tuning of integration time in each cell of the readout integrated circuit. Relatively high steepness and conversion linearity are maintained in integrating cells under moderate irradiation (up to 50–70% of the maximum signal) but the sensitivity is decreased in the cells that are close to saturation. The resulting linear–logarithmic transfer function provides extension of the dynamic range. Examples of images obtained with the extended dynamic range in the short-wavelength IR spectrum are presented.