Measuring method for a surface structure of a material by lighting up the surface with drag light and photographing it electronically with a CCD-camera

摘要

The method involves lighting up a surface (11) with drag light and photographing it electronically with a CCD-camera (15). A Fourier transformation is made in order to a get a spectrum of the intensity in the picture obtained. At least two pictures are taken in a row with drag light from various directions, with an angle of 30-120 degrees between the light directions as projected on the plane of the surface. A Fourier transformation is made on each picture. The entire spectrum or a part of the spectrum of each pictures is taken and added to the spectrum in order to create an approximation of the accurate spectrum of the surface. From each picture the mean value of the light of the picture is subtracted before making the Fourier transformation.