Abstract: Apparatus for analyzing a surface which, in use, is subject to drag, the apparatus comprising, a light source for generating light of at least one predetermined wavelength, a light source holder for holding and positioning the light source so as to direct it at the surface, a light detector for detecting reflected light from the surface and generating a signal in response thereto, a light detector holder for holding the light detector and positioning it so as to detect the reflected light, and a connector for connecting the light detector to a microprocessor to analyze the signal. Also disclosed is a method of analyzing a surface which, in use, is subject to drag.