Object illumination method with sinusoidal intensity distributions

摘要

The method involves using a cyclic amplitude or a cyclic phase structure in a transparent material, in the form of a relief structure, which is designed so that the illumination is focused as sharply as possible on the surface to be measured. With a suitable form of light wave structure, combined with a spatial filtering in an optical imaging channel, this is supplied for an adequate depth of focus and with a truly sinusoidal shape. The cyclic phase structure is a Ronchi structure.