Recent advances in photographic sensing technologies have made it possible to achieve light detection in terms of a single photon. Photon counting sensors are being increasingly used in many diverse applications. We address the problem of jointly recovering spatial and temporal scene radiance from very few photon counts. Our ConvNet-based scheme effectively combines spatial and temporal information present in measurements to reduce noise. We demonstrate that using our method one can acquire videos at a high frame rate and still achieve good quality signal-to-noise ratio. Experiments show that the proposed scheme performs quite well in different challenging scenarios while the existing approaches are unable to handle them.
@cite_30: Active optical imaging systems use their own light sources to recover scene information but typically operate with large number of photon detections. Here, the authors present a 3D imaging system that acquires depth and reflectivity information with a single photon camera operating in low-light conditions.
@cite_14: A compact real-time fluorescence lifetime imaging microscopy (FLIM) system based on an array of low dark count 0.13?m CMOS singlephoton avalanche diodes (SPADs) is demonstrated. Fast background-insensitive fluorescence lifetime determination is achieved by use of a recently proposed algorithm called ‘Integration for Extraction Method’ (IEM) [J. Opt. Soc. Am. A 25, 1190 (2008)]. Here, IEM is modified for a wider resolvability range and implemented on the FPGA of the new SPAD array imager. We experimentally demonstrate that the dynamic range and accuracy of calculated lifetimes of this new camera is suitable for widefield FLIM applications by imaging a variety of test samples, including various standard fluorophores covering a lifetime range from 1.6ns to 16ns, microfluidic mixing of fluorophore solutions, and living fungal spores of Neurospora Crassa. The calculated lifetimes are in a good agreement with literature values. Real-time fluorescence lifetime imaging is also achieved, by performing parallel 32 × 16 lifetime calculations, realizing a compact and low-cost FLIM camera and promising for bigger detector arrays.
@cite_25: We present the architecture and three applications of the largest resolution image sensor based on single-photon avalanche diodes (SPADs) published to date. The sensor, fabricated in a high-voltage CMOS process, has a resolution of 512 × 128 pixels and a pitch of 24 ?m. The fill-factor of 5 can be increased to 30 with the use of microlenses. For precise control of the exposure and for time-resolved imaging, we use fast global gating signals to define exposure windows as small as 4 ns. The uniformity of the gate edges location is ?140 ps (FWHM) over the whole array, while in-pixel digital counting enables frame rates as high as 156 kfps. Currently, our camera is used as a highly sensitive sensor with high temporal resolution, for applications ranging from fluorescence lifetime measurements to fluorescence correlation spectroscopy and generation of true random numbers.
@cite_24: The recent availability of miniaturized photon-counting pixels in standard CMOS processes has paved the way to the introduction of photon counting in low-cost time-of-flight cameras, robotics vision, mobile phones, and consumer electronics. In this paper we describe the technology at the core of this revolution: single-photon avalanche diodes (SPADs) and the architectures enabling SPAD based image sensors. We discuss tradeoffs and design trends, often referring to specific sensor chips and applications.
SPAD sensors are photodetectors in which photon radiation can be detected from the resulting large avalanche currents. SPAD sensor arrays are capable of photon counting at a high speed with high timing resolution and are useful in a variety of applications such as fluorescence lifetime imaging microscopy (FLIM), positron emission tomography (PET), time-of-flight imaging etc. @cite_30 @cite_24 @cite_14 . Recently, developed a SPAD array known as SwissSPAD @cite_25 . The SwissSPAD is fabricated in a high-voltage CMOS process and features a large 512 @math 128 array with global gating. In this paper, we use data from different SwissSPAD sensor arrays for demonstrating our high speed video recovery scheme.