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1 September 1991 Design of an IR non-lens, or how I buried 100 mm of germanium
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At the International Lens Design Conference (ILDC) in Monterey, California, one of the design problems posed was to create a `non-lens' (a lens which did nothing) to within the diffraction limit of any ray which passed through the system, but which used exactly 100 mm of glass. The lens has an entrance and exit aperture which are separated by 250 mm, the aperture of which is to be made as large as possible, such that any ray which enters the first hole and exits the second does so as it would have if the lens were removed to within the diffraction limit (<0.07 waves RMS wavefront error.) In short, use 100 mm of glass and do nothing to the light which goes through it. The author, along with several colleagues at the design conference who also work primarily in the long-wave infrared (LWIR) waveband, reposed the problem in terms of IR materials and wavelengths. The design problem was studied in the IR. Instead of glass, Germanium (n equals 4.00) was used, and instead of designing for the visible diffraction limit of 0.588 micrometers , a diffraction limit at 10 micrometers was used. This paper documents the results of that study, with particular attention paid to the differences between the visible and IR solutions. By no means have all of the solutions to the problem been found, but the higher index and much higher diffraction limit result in some fascinating solutions.
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
David M. Aikens "Design of an IR non-lens, or how I buried 100 mm of germanium", Proc. SPIE 1485, Reflective and Refractive Optical Materials for Earth and Space Applications, (1 September 1991);


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