Residual surface roughness of diamond-turned optics

Abstract

The residual surface roughness of diamond-turned optics is expected to contain significant periodic components. The optical properties of such surfaces are explored as a special case of Rayleigh-Rice vector scattering theory applied to periodic roughness with vertical amplitudes much smaller than the wavelength of light. Expressions are given for the interpretation of differential-scatter, total-integrated-scatter, reflectometry, and ellipsometric measurements in the limit of a highly conducting. surface. In general, such measurements give varying degrees of information about the two-dimensional power spectral density of the surface roughness within the nominal range from the wavelength of light to the diameter of the probing beam spot. Such information may be useful for the practical characterization of mirror surfaces.

<title>Light-Scattering Characteristics Of Optical Surfaces</title>

“…Recently there has been a great deal of activity in the area of BRDF measurements of machined metal mirrors to be used in high-energy laser applications (Young, 1975;Curcio, 1975;Decker, Bennett and Bennett, 1975;Church and Zavada, 1975;and Stover, 1975).…”

Surface Roughness Studies with DALLAS-Detector Array for Laser Light Angular Scattering

“…1) according to the laws of physical optics. The intensity and the pattern of the scattered radiation depend on the roughness heights, the roughness spatial wavelengths, and the wavelength of the light [6][7][8]. In general, small spatial wavelength components diffract the light into large angles relative to the specular direction, and long spatial wavelength components diffract the light into small angles.…”

“…However, this means that the roughness heights are on the same order of magnitude as the wavelength of light [5]. The mathematical description is much more complicated in this regime than it is for optically smooth surfaces [6,7] where the effect of surface roughness is a small perturbation on the basic phenomenon of specular optical scattering, i.e., where the surface basically functions like a mirror.…”

Light Scatterometry as an NDE Technique for Surface Characterization of Ge Windows

“…Light scattering techniques are currently being used for examining the surface quality of various optical components [4]. The statistical parameters that characterize surface roughness [5] can readily be obtained from light scatter measurements [6].…”