As freeform optics become more prevalent, it is important for manufacturers to have flexibility when fabricating such optics. Traditionally, QED's Magnetorheological Finishing (MRF™) machines have used a raster toolpath to polish optics that lack rotational symmetry in either their aperture shape or surface form. However, a spiral toolpath may be desirable for a variety of reasons: to achieve a tighter edge exclusion, to correct rotationally-symmetric features, or to polish high- NA optics that may exceed the half-angle limits of raster polishing. In this paper we present a new spiral toolpath polishing capability for surfaces that have circular apertures but have a surface form that lacks rotational symmetry. This enables rotationally polishing freeform optics, such as off-axis parabolas (OAPs) and toroids, in addition to tilted plano surfaces or wedged (non-centered) spheres. We will explain the capabilities of this new polishing mode and present initial polishing results.
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