METHOD OF MANUFACTURING A VARIABLE EFFICIENCY DIFFRACTIVE GRATING AND A DIFFRACTIVE GRATING

The invention concerns a method of manufacturing a modulated optically diffractive grating and a corresponding grating. The method comprises providing a substrate and manufacturing a plurality of temporary elements onto the substrate, the temporary elements being arranged in a periodic pattern comprising at least two periods having different element characteristics. Next, a first deposition layer is deposited so as to at least partially cover the temporary elements with the first deposition layer and the temporary elements are removed from the substrate in order to form onto the substrate a modulated diffractive grating of first grating elements made of the first deposition layer, the pattern comprising within each period a plurality of first grating elements and one more gaps between the first grating elements. The invention allows for producing high-quality gratings with locally varying diffraction efficiency.