A 160×128 single-photon image sensor with on-pixel 55ps 10b time-to-digital converter

Single-Photon Avalanche Diode Imagers Applied to Near-Infrared Imaging

“…The relatively small field of view of the presented system was limited by the size of the sensor's active area (3.2 mm × 3.2 mm). Although sensors with larger active areas have been developed [17], they are still small in comparison to commercial CCD and CMOS sensors. So far most SPAD pixels integrated in image sensors exhibit low fill-factors, making them inefficient in low light applications like NIRI.…”

“…This is a drawback, because the ultimate aim is to perform measurements on human subjects in, or close to, real time to avoid artifacts from physiological changes and from the motion of the subject. Recently, SPAD image sensors have integrated TDCs in-pixel [17], i.e. all pixels in the sensor may simultaneously perform time-resolved measurements.…”

Introduction to time-of-flight imaging

“…Amongst D-TOF, a notable sensor is the aforementioned 4x64 array based on amplified gated photodetection, capable of a centimetric accuracy at up to 8 meters with use of a pulsed illuminator of 200W of peak power operating at 850-910nm of wavelength [3], [4]. Amongst SPAD TCSPC systems, after a flurry of sensors appeared in the mid 2000s [8]- [15], a notable system is a SiPM capable of achieving a 3D image of 202x96 pixels by MEMS scanning and a laser source with a divergence in time of 4ns and in space of 1.5 (V) and 0.05 (H) degrees [30]. The sensor comprises 16 SiPMs, each consisting of 24 SPADs for TOF and 32 SiPMs, each consisting of 12 SPADs for background capturing, effectively reducing the dead time to 10ns.…”

“…Massa et al and Albota et al showed the use of a single or a few SPADs with a collimated laser illuminator operating in time-correlated single-photon counting (TCSPC) mode [5], [6], [7]. More recently, the integration of SPADs in CMOS enabled the creation of large SPAD arrays with timeto-digital converters (TDCs) [8] and time-to-amplitude converters (TACs) [9] on chip [8], on-column [10], [11], and even side-by-side to the pixels [12], [13], [14], [15]. Fig.…”

Sensor network architecture for a fully digital and scalable SPAD based PET system

“…The inherent digital property of SPADs and their migration to deep submicron CMOS processes have enabled the realization of digital photonic sensors with built-in intelligence [4]. Deep-submicron CMOS SPADs, along with 3-D integration will lead to highly granular pixel arrays, capable of time-stamping individual photons, the ideal sensing solution in PET systems.…”