DIFFRACTION GRATINGS AND THE MANUFACTURE THEREOF

摘要

A diffraction grating (1) includes a surface (12) having grooves (14) therein, said grooves (14) being separated from each other by lands (20) upon the surface (12) of varying width, whereby the diffractive efficiency varies across the extent of the grating (1). The land width (22) may vary along its length, the groove depth may vary along its length and/or the pitch (16) of the grooves (14) may vary across the extent of the grating (1).