Reviews Online

In a recent preprint ( https://arxiv.org/pdf/2209.11772.pdf ) Gyongy et al. describe a new 64x32 SPAD-based direct time-of-flight sensor with in-pixel histogramming and processing capability. Abstract 3D flash LIDAR is an alternative to the traditional scanning LIDAR systems, promising precise depth imaging in a compact form factor, and free of moving parts, for applications such as self-driving cars, robotics and augmented reality (AR). Typically implemented using single-photon, direct time-of-flight (dToF) receivers in image sensor format, the operation of the devices can be hindered by the large number of photon events needing to be processed and compressed in outdoor scenarios, limiting frame rates and scalability to larger arrays. We here present a 64 × 32 pixel (256 × 128 SPAD) dToF imager that overcomes these limitations by using pixels with embedded histogramming, which lock onto and track the return signal. This reduces the size of output data frames considerably, enabling max

The June 2022 issue of IEEE Trans. Electron. Devices has an invited paper titled Direct Time-of-Flight Single-Photon Imaging by Istvan Gyongy et al. from University of Edinburgh and STMicroelectronics.  This is a comprehensive tutorial-style article on single-photon 3D imaging which includes a description of the image formation model starting from first principles and practical system design considerations such as photon budget and power requirements. Abstract: This article provides a tutorial introduction to the direct Time-of-Flight (dToF) signal chain and typical artifacts introduced due to detector and processing electronic limitations. We outline the memory requirements of embedded histograms related to desired precision and detectability, which are often the limiting factor in the array resolution. A survey of integrated CMOS dToF arrays is provided highlighting future prospects to further scaling through process optimization or smart embedded processing. Full paper:  https://doi

Photonics magazine has a new article about Pi Imaging Technology's high resolution SPAD sensor array; some excerpts below. As the performance capabilities and sophistication of these detectors have expanded, so too have their value and impact in applications ranging from astronomy to the life sciences. As their name implies, single-photon avalanche diodes (SPADs) detect single particles of light, and they do so with picosecond precision. Single-pixel SPADs have found wide use in astronomy, flow cytometry, fluorescence lifetime imaging microscopy (FLIM), particle sizing, quantum computing, quantum key distribution, and single- molecule detection. Over the last 10 years, however, SPAD technology has evolved through the use of standard complementary metal-oxide-semiconductor (CMOS) technology. This paved the way for arrays and image sensor architectures that could increase the number of SPAD pixels in a compact and scalable way.  Compared to single-pixel SPADs, arrays offer improved

"Photon counting cameras for quantum imaging applications"  Prof. Edoardo Charbon, Full Professor, Advanced Quantum Architecture Lab Abstract: Photon counting has entered the realm of image sensing with the creation of deep-submicron CMOS SPAD technology. The format of SPAD image sensors has expanded from 8×4 pixels in 2004 to the recent megapixel camera in 2019, and the applications have literally exploded in the last few years, with the introduction of proximity sensing and portable telemeters. SPAD image sensors are today in almost every smartphone and will soon be in every car. The introduction of Quanta Burst Photography has created a great opportunity for photon counting cameras, which are ideally suited for it, given its digital nature and speed; it is however computationally intensive. A solution to this problem is the use of 3D stacking, introduced for SPADs in 2015, where large silicon real estate is now available to host deep-learning processors, neural networks di

Krister Shalm of National Institute of Standards and Technologies presented a tutorial: Single-photon detectors at the 2013 QCrypt Conference in August. http://2013.qcrypt.net This is from a while back but an excellent educational resource nevertheless! The video is roughly 90-minutes long but has several gaps that can be skipped ahead. Or play it at >1x speed! Full video here: https://www.youtube.com/watch?v=Vt84rSJa7VI&t=541s