A fibre-optic surface-roughness sensor

A technique applicable to surface-roughness measurement in limited spaces is presented. The measurement principle is Light scattering, the surface under test being illuminated using a He-Ne laser, lambda = 632.8 nm, with the light being lead to the surface by an optical fibre. The light scattered by the surface is lead by a fibre to a detector. This arrangement makes a very small system possible, a system that can be used to make relative surface-roughness measurements inside a tube or a cylinder. The experimental results presented in this paper show the applicability of this sensor. The surfaces were classified in the same order as when using a stylus instrument. Surfaces in the range of 10 nm < R-a < 200 nm were measured, R-a being the arithmetical mean deviation of the profile. (C) 1999 Elsevier Science S.A. All rights reserved.