FOCAL-PLANE ARRAYS: Curved sensor array to help simplify cameras

摘要

As every camera-lens designer knows, the need to produce flat image planes drives up the mass and complexity of camera optics. And the image sensors in digital cameras are, if anything, flatter than the photographic film that lens designers have been contending with for more than a hundred years. But researchers at Stanford University have taken advantage of the wonders of optical lithography to develop a monolithic but flexible silicon digital-sensor geometry that can easily conform to nonplanar contours; they have chosen the sphere (actually, a section thereof) as the contour that leads to the simplest lens designs. In their sensor, each pixel exists on its own little silicon island (see Fig. 1), with all pixels laid out in the usual rectilinear geometry. Each island is connected to its four neighbors only by thin silicon springs, allowing the overall pixel surface to deform as if it were a stretchable rubber sheet. For example, a prototype device made of a square array 1 X 1 cm~(2) in size with 105 X 105 islands (although containing no active pixels) fabricated from silicon 30 (mu)m thick was deformed into a subhemispherical dome having a mere 1 cm radius.