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. 1994 Sep-Oct;99(5):641–671. doi: 10.6028/jres.099.059

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The Journal of Research of the National Institute of Standards and Technology is a publication of the U.S. Government. The papers are in the public domain and are not subject to copyright in the United States. Articles from J Res may contain photographs or illustrations copyrighted by other commercial organizations or individuals that may not be used without obtaining prior approval from the holder of the copyright.

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Fig. 4 — Drawing of the comparison between different types of “pinhole” tenses. (a) Early version flat lens; (b) 45° conical lens; (c) 60° conicat lens.