Real-time color imaging with a CMOS sensor having stacked photodiodes

Abstract

High-performance color image acquisition has heretofore relied on color video cameras using multiple image sensors mounted on spectral separation prisms to provide geometrically accurate color data free of reconstruction artifacts. Recently, a CMOS image sensor has been developed that incorporates three complete planes of photodiodes in a single device to provide color separation without the need for external optical elements. The first commercial device based on this technology has 1512 x 2268 three-color photosites on 9.12 micron centers and includes provisions for combining pixels in X and Y, region-of interest selection and sparse scanning. The camera described in this paper operates the sensor in a variety of scan modes offering tradeoffs between resolution, coverage and speed. In this camera, a 128x128 raster of either a matrix of this size or binned from a large area can be scanned at nearly 150 frames per second and a single 2048-element line can be scanned at 7 KHz. At full resolution, the image sensor will acquire four frames per second. The scan configuration can be reloaded in less than 50 microseconds permitting mod e changes on the fly.