Accelerated frame-free time-encoded multi-step imaging

This paper presents a frame-free time-domain imaging approach designed to alleviate the non-ideality of finite exposure measurement time (intrinsic to all integrating imagers), limiting the temporal resolution of the ATIS asynchronous time-based image sensor concept. The method uses the time-domain correlated double sampling (TCDS) and change detection circuitry already present in the data-driven autonomous ATIS pixels and does not involve any additional data to be transmitted by the sensor, but is entirely based on the data available in normal operation. Three consecutive exposure estimation / measurement steps apply different trade-offs between measurement speed, accuracy and noise. The early estimates yield between 10 and 100 times faster pixel updates than the standard full-swing integrating exposure measurement operation. The results from the three individual measurement steps can be used separately or in combination, enabling event-driven asynchronous high-speed imaging at moderate light levels.