Importance

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Abstract

A faceplate for a highly sensitive low-light level imaging device is provided with an off-axis light filter to reduce optical noise. A transparent optical conduit layer includes an absorbing region around the periphery to absorb off-axis light. A transparent front plate extends beyond the periphery of the conduit and forms a shoulder of easily polished glass to facilitate the sealing of the faceplate to the imaging device frame. A clear glass back plate extends so as to cover the entire inner surface of the conduit including the absorbing region, thereby providing an easily and consistently polishable surface upon which to bond a photosensitive semi-conductor wafer. This reduces the necessity for matching of glass compositions between the core and the absorbing region. The absorbing region may be a toroidal area of black glass or it may be composed of a matrix of glass having the same composition as the rest of the faceplate but having absorbing glass fibers embedded more or less radially of the axis of the conduit. In the latter case the need for glass matching is virtually eliminated.

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First Claim