Use of adaptive integration time to improve the dynamic range of a focal plane array

摘要

We provide a block diagram of an array element in a large-scale integrated photosignal read circuit with adaptive integration time (which, in this application, depends on the ambient light level). We propose a mathematical description of the light detection process using a focal-plane array with this type of large-scale integrated circuit. We demonstrate that if the focal-plane array transfer function is nonlinear (due to the additive integration time), this will expand the input-signal dynamic range to 130-140 dB. We conclude that a focal-plane array with a log-linear transfer function has a better signal-to-noise ratio (10%-30% higher, with low input current) than one with a logarithmic transfer function, with no degradation to the dynamic range. We provide equations to obtain the dynamic range and signal-to-noise ratio from the transfer function for a focal-plane array. (C) 2017 Optical Society of America