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Proceedings Paper

Precision optics fabrication using magnetorheological finishing
Author(s): Donald Golini; Stephen D. Jacobs; William I. Kordonski; Paul Dumas
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Paper Abstract

Optical polishing with magnetic media has evolved extensively over the past decade. Of the approaches conceived during this time, the newest process is called magnetorheological finishing (MRF). In MRF, all of the process parameters are controlled by utilizing the state of hydrodynamic flow of a magnetically stiffened magnetorheological abrasive fluid through a converging gap formed by a lens workpiece surface and a moving wall. The shear flow of “plastic” MR fluid results in the development of high stresses in the interface zone and material removal over a portion of the workpiece surface, referred to as the “polishing spot”. The polishing spot is an abrasive-charged, sub-aperture lap that automatically conforms to the local shape of the lens surface. Deterministic finishing is accomplished by mounting a lens on a rotating spindle and sweeping it through the MR fluid with a computer numerical controlled (CNC) machine. A computer program generates both a dwell time schedule for the MRF machine and an accurate prediction of finished surface shape, using a material removal function and initial surface condition information as input. In this paper, we describe the MRF process, a preliminary theory of material removal, properties of the MR fluid, machine configurations, software for finishing, and finishing experiments on a variety of surface shapes (spherical, flat, aspheres) and materials of interest to optics manufacturing. Advantages and current limitations to the process are also described.

Paper Details

Date Published: 28 July 1997
PDF: 24 pages
Proc. SPIE 10289, Advanced Materials for Optics and Precision Structures: A Critical Review, 102890H (28 July 1997); doi: 10.1117/12.279809
Show Author Affiliations
Donald Golini, QED Technologies, LLC (United States)
Stephen D. Jacobs, Ctr. for Optics Manufacturing (United States)
William I. Kordonski, QED Technologies, LLC (United States)
Paul Dumas, QED Technologies, LLC (United States)

Published in SPIE Proceedings Vol. 10289:
Advanced Materials for Optics and Precision Structures: A Critical Review
Mark A. Ealey; Roger A. Paquin; Thomas B. Parsonage, Editor(s)

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