Proceedings PaperZoom lenses for small CCD cameras
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Electronic systems are rapidly replacing photographic systems for most imaging applications, and in a short period of time the actual size of the sensor has been decreasing. For consumer applications the half-inch CCD is replaced by the one-third inch CCD, and the quarter-inch CCD now has been introduced. Assuming no loss of pixels, lens designs for the newer formats could be derived by simply scaling down the existing larger format designs, changing the thickness slightly to accommodate the necessary minimum edges and spaces. But by recognizing that a minimum edge of 1 mm is 25% of the 4 mm image diagonal for a quarter- inch CCD, it becomes evident that even if conventional spherical glass lens technology is employed a new type of lens design is needed. Because the lens element volumes are so small, however, consideration of molded lenses, either glass or plastic, would appear worthwhile. More particularly for consumer and commercial applications most lenses 'zoom' because there are no surplus pixels, foregoing the possibility of electronic 'zooming' to effect a change of angular resolution of the object. The following describes the development of vari-focal and zoom lenses for small image formats that can be fabricated entirely by molding processes.