Determining local thickness of layer in stack of layers in grooved optical disk, e.g. for CD-RW production, by performing measurements at at least as many different wavelengths as there are layers to be measured

摘要

A measuring light beam (15) is directed at an angle of incidence between 0 and 20 degrees onto the stack (11), and the thickness of the layer is determined from the intensity light transmitted and/or reflected in zero order and at least one further diffraction order. To determine the thicknesses of adjacent layers (12,13,14) arranged between a substrate (27) and a protective layer (28), measurement is performed at at least as many different wavelengths as there are layers to be measured. An Independent claim is also included for a measuring device.