Two-Dimensional SPAD Imaging Camera for Photon Counting

Many demanding photonic applications require the acquisition of images at very low light-level conditions and at high speed. Advanced imagers available on the market are generally not able to provide both performances in one detector. We present a 2-D imager based on a 32 × 32 array of “smart pixels,” each comprising a single-photon avalanche diode detector, an analog front end, and a digital processing electronics, which provides single-photon sensitivity, high electronic noise immunity, and high readout speed. The imager can be operated at a maximum of about 100 000 frame/s with negligible blind time between frames, provides high Photon-Detection Efficiency in the visible range and dynamic range, and low Dark-Counting Rate, even at room temperature. To easily integrate the imager into different applications, we developed a complete single-photon camera system, which fully operates the array simply through a USB 2.0 link and user-friendly software to configure camera parameters and operating modalities, as well as to perform readout.