Surface roughness meter for the range 1–25 nm based on the scattered-light indicatrix

A description is given of an instrument for measuring the surface roughness, based on determination of the scattering indicatrix of laser radiation and characterised by a dynamic range corresponding to the intensity ratio 10⁶. The capabilities of this instrument were demonstrated by measurements on special roughness test objects, diamond-turned mirrors, and high-quality polished metal surfaces.