High speed, ultra-low photon flux imaging

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The development of imaging systems has historically been focussed on the design of optics and camera technologies. Major advances have been made in electronic detectors, including compact silicon pixel arrays, and small form-factor lenses, making visible light cameras cheap, high resolution and mass producible. These devices also underpin advances in bio-medical and remote imaging where greater pixel density and therefore resolution has been the major goal. Future systems require performance that goes well beyond simple image capture. Accurate timing information provides access to 3D imaging techniques, while smart image processing and spatially tunable optics can produce sub-diffraction limited images. Operation of cameras in the few photon limit can make use of correlation effects, beating classical limits and offering security. To enable these kinds of imaging applications optical sources must be considered in parallel with the detector technologies.At the Institute of Photonics we have been developing micro-LED display technologies with remarkable performance parameters. Each pixel is only a few microns in diameter and can be switched at 100's of MHz rates, with pulse widths of nanosecond duration. Arrays of these pixels are bonded directly onto CMOS drive electronics providing unprecedented control over their spatio-temporal output. The spatially structured light-field gives access to an entirely new form of illumination that has shown application in visible light communications and indoor navigation. This project will develop the potential of spatio-temporal illumination sources further, targeting their operation at ultra-low light levels in the single photon range. By using Single Photon Avalanche Detector (SPAD) arrays, we will be able to create correlations of generated and detected photons in both space and time. This ability will allow the capture of images with extremely few photons, combined with sparse image processing techniques. The applications of these imaging systems include low flux biological systems, underwater data communications and navigation, and quantum imaging and robotic control.The PhD student will have access to state-of-the-art LED and SPAD arrays with which to create next generation imaging systems. They will develop spatio-temporal modulation and decoding schemes for low flux imaging and navigation, implementing these using custom electronics. The systems will be demonstrated in macro and micro-scale imaging applications.