1 March 2004 Metrology of thin transparent optics using Shack-Hartmann wavefront sensing
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Abstract
The surface topography of thin, transparent materials is of interest in many areas. Some examples include glass substrates for computer hard disks, photomasks in the semiconductor industry, flat panel displays, and x-ray telescope optics. Some of these applications require individual foils to be manufactured with figure errors that are a small fraction of a micron over 10- to 200-mm lengths. Accurate surface metrology is essential to confirm the efficacy of manufacturing and substrate flattening processes. Assembly of these floppy optics is also facilitated by such a metrology tool. We report on the design and performance of a novel deep-ultraviolet (deep-UV) Shack-Hartmann surface metrology tool developed for this purpose. The use of deep-UV wavelengths is particularly advantageous for studying transparent substrates such as glass, which are virtually opaque to wavelengths below 260 nm. The system has a 143×143-mm2 field of view at the object plane. Performance specifications include 350-µrad angular dynamic range and 0.5-µrad angular sensitivity. Surface maps over a 100 mm diam are accurate to <17-nm rms and repeatable to 5 nm rms.
© (2004) Society of Photo-Optical Instrumentation Engineers (SPIE)
Craig R. Forest, Claude R. Canizares, Daniel R. Neal, Michael McGuirk, Mark Lee Schattenburg, "Metrology of thin transparent optics using Shack-Hartmann wavefront sensing," Optical Engineering 43(3), (1 March 2004). https://doi.org/10.1117/1.1645256 . Submission:
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