Optical coding of SPAD array and its application in compressive depth and transient imaging

Abstract

Time-of-flight depth imaging and transient imaging are two imaging modalities that have recently received a lot of interest. Despite much research, existing hardware systems are limited either in terms of temporal resolution or are prohibitively expensive. Arrays of Single Photon Avalanche Diodes (SPADs) are promising candidates to fill this gap by providing higher temporal resolution at an affordable cost. Unfortunately, state-of-the-art SPAD arrays are only available in relatively small resolutions and low fill-factor. Furthermore, the low fill-factor issue leads to more ill-posed problems when seeking to realize the super-resolution imaging with SPAD array. In this work, we target on hand-crafting the optical structure of SPAD array to enable the super-resolution design of SPAD array. We particularly investigate the scenario of optical coding for SPAD array, including the improvement of fill-factor of SPAD array by assembling microstructures and the direct light modulation using a diffractive optical element. A part of the design work has been applied in our recent advance, where here we show several applications in depth and transient imaging.