Large-Format, High-Throughput Photon-Counting Imager

Low‐cost, power‐efficient, time‐resolved imaging is increasingly important for Department of Energy remote‐sensing operations. Today’s remote‐sensing operations use photocathode‐based technologies, such as intensified CCDs and CMOS cameras, hybrid image tubes, and hybrid cross‐strip anode image intensifiers. These solutions are expensive, bulky, cannot support high count rates, have low throughput, consume too much power, and have limited area‐coverage and reliability rates. A time‐gated and asynchronous time‐resolved, high‐ throughput, solid‐state, silicon, 1024 x 1024‐element, single‐photon‐counting imaging array, referred to as the time‐ resolved single‐photon avalanche diode (τSPAD) sensor, is being developed. The τSPAD sensor will be sensitive throughout the visible and near‐infrared spectral ranges and will be able to capture a single photon’s spatial location to better than 20 µm and time of arrival to better than 100 ps at GHz count rates. The τSPAD sensor is being developed in a high‐volume, commercial, complementary metal‐oxide‐semiconductor (CMOS) fabrication processes, offering significant cost and scale advantage. Critical specifications for the τSPAD sensor were refined based on DOE requirements and commercial market needs. Top‐level system design, modeling, and trade studies, were performed. A novel, low‐ power, low‐footprint, imager architecture was designed and simulated. All major building blocks of the τSPAD sensor were verified and demonstrated. The τSPAD sensor design will be completed and released for fabrication. Upon fabrication, the chip will be packaged and integrated into Voxtel’s existing brassboard camera platform. Following integration, extensive electrical and optical test and characterization will be performed and sensor performance will be verified against specifications. The τSPAD sensor is generally applicable to three‐dimensional time‐ of‐flight imaging applications. The large format, low noise, and high throughput will directly translate into high area coverage rates, greater ability to operate under high background conditions, higher sensitivity in wide‐area search applications, more‐detailed three‐dimensional imaging without mechanical scanning systems and noiseless motion correction with long effective shutter times. Applications include: lidar, with the ps‐scale resolution of the τSPAD, including automotive navigation, collision avoidance, adaptive cruise control, surveillance, aviation takeoff and landing, unmanned aircraft, and machine vision; and medical imaging, including optical coherence tomography for mammography, neonatal imaging, and improved resolution and throughput in time‐of‐flight positron emission tomography. Furthermore, the innovation benefits the public as it has widespread utility in numerous fields and national security, such as remote sensing for nuclear proliferation detection. Overall, it is an enabling technology for several important scientific, medical, industrial, and consumer applications.