A 16 × 16 pixel silicon on sapphire CMOS photosensor array with a digital interface for adaptive wavefront correction

We report on a 16 × 16 pixel CMOS photosensor array fabricated in silicon on sapphire CMOS technology. The transparency of the substrate allows imaging from both the back and front side and opens new applications for CMOS active pixel sensor arrays. A digital asynchronous interface is employed to minimize the design complexity and the power consumption. The analog pixel value is encoded as a pulse density stream of address events. The multiple threshold MOS transistors available in this technology enable circuit optimizations for low power and low voltage operation. We characterize the pixel sensitivity and show experimental data from both back and front side imaging.