Time-resolved imaging is a fundamental tool for biomedical applications such as fluorescence lifetime imaging microscopy (FLIM) and mapping of tissue optical parameters. FLIM, in particular, enables us to study the micro-environment of fluorophores in cell biology, providing relevant information like pH, ion concentration and molecular coupling (e.g. FRET).
Compressed sensing approaches, based on image sparsity, have been recently proposed as a novel imaging paradigm allowing to preserve information content while significantly reducing the number of measurements. Single Pixel Camera (SPC) approach is one possible implementation of this idea. The object is imaged on a spatially modulated system (e.g. DMD, SLM), then by focusing the exiting light on a single pixel detector, the inner product between image and pattern is measured.
In this work we propose and validate a novel scheme of time-resolved camera with ps temporal resolution where all the elements required for compressed sensing are combined into a single chip, allowing a significant cost reduction, compactness and performance improvement. The proposed device is based on a high-density array of detection elements, operating in the single photon regime, which can be selectively enabled/disabled. All pixels are connected to one single Time-to-Digital Converter (TDC). In order to experimentally validate the imaging and temporal capability of the proposed system, fluorescence lifetime imaging and time-gated imaging in a diffused medium have been carried out. We believe the proposed time-resolved camera can be a convenient approach in many biomedical applications where a gated camera or a time-resolved scanning system are currently used.
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