Modifying a widely used convention is rarely easy. With designers, fabricators, and metrologists gathered here, we have a rare opportunity to consider such a change in relation to optical aspheres. This evolving technology is currently burdened by the increasingly inadequate convention of expressing a rotationally symmetric asphere’s sag as the sum of a conic component and an additive polynomial. When more than just a few terms appear in the polynomial, this becomes problematic and ultimately unworkable. Many of us are being burned by the fact that the associated coefficients are woefully unintuitive and inefficient. The norm is error-prone communications and a lack of easy options to appreciate the difficulty of manufacturing any particular asphere. Thankfully, the design and manufacture of increasingly complex aspheres is facilitated by a modified representation that is also ideal for exploiting cost-effective shapes. In particular, an orthogonalised representation gives a description that functions with fewer coefficients _typically using only one third the number of digits for current designs_and allows easy interpretations and sanity checks as well as direct assessments of manufacturability. Examples are presented to motivate us to confront this sooner rather than later.
© 2010 OSA, SPIE
G. Forbes, "Better Ways to Specify Aspheric Shapes Can Facilitate Design, Fabrication and Testing Alike," in International Optical Design Conference and Optical Fabrication and Testing , OSA Technical Digest (CD) (Optical Society of America, 2010), paper JMA1.
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