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Proceedings Paper

New schemes in the adjustment of bendable elliptical mirrors using a long trace profiler
Author(s): Seung Yu Rah; Scott C. Locklin; Steven C. Irick; Malcolm R. Howells
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Paper Abstract

The Long Trace Profiler, an instrument for measuring the slope profile of long X-ray mirrors, has been used for adjusting bendable mirrors. Often an elliptical profile is desired for the mirror surface, since many synchrotron applications involve imaging a point source to a point image. Several techniques have been used in the past for adjusting the profile measured in height or slope of a bendable mirror. Underwood et al. have used collimated X- rays for achieving a desired surface shape for bent glass optics. Nonlinear curve fitting sing the simplex algorithm was later used to determine the best fit ellipse to the surface under test. A more recent method uses a combination of least squares polynomial fitting to the measured slope function in order to enable rapid adjustment to the desired shape. The mirror has mechanical adjustments corresponding to the first and second order terms of the desired slope polynomial, which correspond to defocus and coma, respectively. The higher order terms are realized by shaping the width of the mirror to produce the optimal elliptical surface when bent. The difference between desired and measured surface slope profiles allows us to make methodical adjustments to the bendable mirror based on changes in the signs and magnitudes of the polynomial coefficients. This technique gives rapid convergence to the desired shape of the measured surface, even when we have no information about the bender, other than the desired shape of the optical surface. Nonlinear curve fitting can be used at the end of the process for fine adjustments, and to determine the over all best fit parameters of the surface. This technique cold be generalized to other shapes such as toroids.

Paper Details

Date Published: 1 November 1997
PDF: 8 pages
Proc. SPIE 3152, Materials, Manufacturing, and Measurement for Synchrotron Radiation Mirrors, (1 November 1997); doi: 10.1117/12.295552
Show Author Affiliations
Seung Yu Rah, Pohang Accelerator Lab. (South Korea)
Scott C. Locklin, Lawrence Berkeley National Lab. (United States)
Steven C. Irick, Lawrence Berkeley National Lab. (United States)
Malcolm R. Howells, Lawrence Berkeley National Lab. (United States)

Published in SPIE Proceedings Vol. 3152:
Materials, Manufacturing, and Measurement for Synchrotron Radiation Mirrors
Peter Z. Takacs; Thomas W. Tonnessen, Editor(s)

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