Optical Method for Measuring Surface Roughness in Two Orthogonal Directions Using Scattered Light.

Abstract

The surfaces of six ground specimens with an arithmetic mean roughness Ra ranging from 0.05 to 1.6μm were illuminated with a halogen lamp. The intensity distribution of the scattered light measured with a CCD camera was approximated by a two-dimensional (2-D) Gaussian function and its broadness was evaluated using the standard deviations (s.d.) σx and σy of the function. The S.d. σx perpendicular to the grinding direction increased with increasing Ra. On the other hand, the s.d. σy parallel to the grinding direction remained almost unchanged regardless of Ra. The distribution of the surface angle θ was calculated from the surface roughness profile. The s.d. σx increased with increasing s.d. σθ_x of the 2-D Gaussian function approximating the distribution of θ as σx=2.02+1.60 lnσθ_x This indicates that the intensity distribution of the scattered light represents the distribution of the surface angle θ.