Smart CCD image sensors for optical metrology and machine vision

Abstract

Two types of CCD image sensors are described. The first sensor is a two-dimensional, synchronous detector/demodulator ("Lock-In CCD") of spatially modulated light fields for applications in heterodyne interferometry and time-of-flight range imaging. Simultaneous measurements of amplitude, phase and background level are carried out at each pixel site. This is made possible by the principle of synchronized, periodic multi-tap sampling and photo charge accumulation. The second sensor, the "Convolver CCD" is capable of performing image acquisition and real-time, parallel convolution with an arbitrary kernel. Tap weight accuracies of typically 2% of the largest tap values have been obtained for a variety of linear filters that are commonly used in machine vision. The sensors have been realized by using a commercially available multi-project wafer CMOS/CCD process. For both sensors, the principle, design, operation and measurement results are presented and discussed.