Bennett J M
Appl Opt. 1976 Nov 1;15(11):2705-21. doi: 10.1364/AO.15.002705.
A brief review of techniques for measuring surface roughness and optical figure is given. One of the most promising of these techniques for measuring the roughness of optical surfaces is interferometry employing fringes of equal chromatic order (FECO). A FECO scanning interferometer is described, which has been used to determine statistics of polished surfaces having roughnesses under 100 A rms. The scanning interferometer resolves square surface elements 2 microm on a side and statistically characterizes the surface in terms of these elements. Height- and slope-distribution functions, rms roughness, rms slope, and modified autocovariance length distributions have been measured for selected optical surfaces. Nearly all surfaces had Gaussian distributions of heights and slopes, but none had Gaussian distributions of autocovariance lengths. Surfaces such as electropolished copper, electroless nickel, and single-point diamond-machined copper were found to have smaller rms slopes than other surfaces of comparable roughness and scattered less than predicted by simple scalar scattering theory.(1,2) On the other hand, heavily scratched surfaces such as polished potassium chloride had larger slopes and produced more scattering than expected from simple theory.
本文简要回顾了测量表面粗糙度和光学面形的技术。这些技术中，用于测量光学表面粗糙度最有前景的方法之一是采用等色序条纹（FECO）的干涉测量法。文中描述了一种FECO扫描干涉仪，它已被用于确定均方根粗糙度低于100埃的抛光表面的统计数据。该扫描干涉仪可分辨边长为2微米的方形表面单元，并根据这些单元对表面进行统计表征。已针对选定的光学表面测量了高度和斜率分布函数、均方根粗糙度、均方根斜率以及修正自协方差长度分布。几乎所有表面的高度和斜率都呈高斯分布，但自协方差长度均无高斯分布。结果发现，诸如电解抛光铜、化学镀镍和单点金刚石加工铜等表面的均方根斜率比粗糙度相当的其他表面小，且散射比简单标量散射理论预测的要少。（1,2）另一方面，诸如抛光氯化钾等划痕严重的表面斜率更大，产生的散射比简单理论预期的更多。
