Custom Smart Image Sensors for Optical Metrology and Machine Vision

Abstract

Thanks to the advances in semiconductor technology it is possible today to fabricate solid state image sensors with 5k×5k and more pixels, while reducing the geometry of the pixels at the same time to 5×5μm2 and less. This enables one to integrate electronic circuitry with each pixel, without compromising the fill factor substantially. Such pixels with added functionality are the basis of custom photo-ASICs, application-specific integrated circuits containing photosensitive elements, and so-called smart image sensors: Single-chip cameras with on-chip analog-to-digital converters for less than $10 are advertised; image sensors have been developed including novel functionality such as real-time selectable pixel size and shape, the capability of performing arbitrary convolutions simultaneously with the exposure, as well as variable, programmable sensitivity of the pixels leading to image sensors with a dynamic range exceeding 100 dB. It is concluded that the possibilities offered by custom smart image sensors will influence the design and the performance of future imaging systems in many disciplines, reaching from optical metrology to machine vision on the factory floor and in robotics applications.