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4 November 1982 Generation Of Off-Axis Aspherics
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A method of precise generation of optical surfaces is described. The work is turned about one axis, while a grinding head or cutting tool is gradually moved across by an arm turning about a second axis. This geometry can be used to directly generate spherical surfaces or aspherical surfaces that we call hulahoids. We analyze the properties of these surfaces to determine how well large paraboloids and their off-axis segments can be generated. Very close approximations are possible, for example, 1.5-m segments of a 10-m paraboloid differ by only 0.6 μm peak to peak from the best fit hulahoid when the focal ratio is f/2, and 60 μm when it is f/0.4. For accurate generation the cutting tool may need numerically controlled travel of 1 mm or less, with the position set as a function of the swirlg arm angle.
© (1982) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
J. R. P. Angel and R. E. Parks "Generation Of Off-Axis Aspherics", Proc. SPIE 0332, Advanced Technology Optical Telescopes I, (4 November 1982); doi: 10.1117/12.933536;


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