METHOD AND APPARATUS FOR RECORDING AN OPTICAL GRATING IN A PHOTOSENSITIVE MEDIUM

摘要

A method and an apparatus (10) for recording optical gratings in a photosensitive medium (14) are provided. The invention uses a phase mask (16) in combination with a scanning of the recording light beam (20). The phase mask, or alternatively the photosensitive medium, is translated along a direction parallel to the scanning of the light beam, so that the period of the recorded grating may be locally adjusted. To ensure a proper recording efficiency over a large wavelength range, an appropriately selected wavefront curvature is provided in the light beam. The method of the invention is particularly advantageous for the recording of superimposed grating components in a photosensitive medium.