Lock-in CCD and the convolver CCD: applications of exposure-concurrentphotocharge transfer in optical metrology and machine vision,

摘要

Abstract: Two types of image sensors are described that exploit the CCD's capability of spatially moving photocharge simultaneously with the exposure to a scene. The lock-in CCD is a two- dimensional array of pixels, each of which is a synchronous detector for oscillating optical wave fields with a spatially varying distribution of phase, amplitude and background offset. Main applications of this novel CCD type are in time-of-flight and heterodyne interferometric range imaging without moving parts. The convolver CCD consists of a two-dimensional array of pixels, connected with their nearest neighbors through short CCD lines, with which photocharge can be transferred vertically and horizontally during the exposure. By suitably timing these charge shifts, freely programmable convolutions with kernels of arbitrary size become possible. Tap weight accuracies of typically 2% of the largest tap value have been obtained for a variety of linear filters that are commonly used in machine vision. An integral part of these CCDs is a programmable, microcontroller-based driver system, capable of generating dynamic pulse sequences and driving virtually any image sensor available commercially or custom designed for special applications. !23