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Proceedings Paper

Spectral Analysis Of The Finish Of Diamond-Turned Mirror Surfaces
Author(s): E. L. Church; M. R. Howells; T. V. Vorburger
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Paper Abstract

This paper discusses the effects of surface topographic scattering on the performance of optical elements and illustrates the results in terms of the focussing mirrors of the Brookhaven plane-grating monochromator. Performance figures are described in terms of the power spectral density of the surface roughness, where the contributing range of surface spatial wavelengths, d, lies between the wavelength of the operating radiation and the aperture of the part: from nanometers to centimeters. This is considerably greater than the range included in "total-integrated scatter" or "TIS" measurements involving visible light at normal incidence: d = 0.65 to 12 pm. In order to explore the contributions of longer surface wavelengths we have measured the profiles of several optical-quality surfaces -- polished, diamond-turned and turned-and-polished -- with a mechanical stylus gauge, and have estimated their power spectral densities over the range d = 2 to 500 pm. The power spectra generally increase with increasing wavelength, although the spectral shapes vary widely. Contributions from d > 12 pm are significant in all of the cases examined, and are completely dominant in several cases. These preliminary results show that any useful characterization of surface finish must involve the power spectral density of its surface roughness over an extended range of surface wavelengths, including the critical long-wavelength region. A general discussion of measurement techniques and performance figures is given to provide a rational basis for the systematic study of these issues.

Paper Details

Date Published: 3 May 1982
PDF: 17 pages
Proc. SPIE 0315, Reflecting Optics for Synchrotron Radiation, (3 May 1982); doi: 10.1117/12.933015
Show Author Affiliations
E. L. Church, U. S. ARRADCOM (United States)
M. R. Howells, Brookhaven National Laboratory (United States)
T. V. Vorburger, U. S. National Bureau of Standards (United States)


Published in SPIE Proceedings Vol. 0315:
Reflecting Optics for Synchrotron Radiation
Malcolm R. Howells, Editor(s)

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