NOVEL GRATING

摘要

A grating comprising a plurality of substantially parallel members having a conducting surface of depth L, separated by a dielectric layer gap, and having of pitch lambda g and where L>16 lambda g. The members are preferably metallic or comprise metallic foil covered plastic. The gap may be filled wholly or partially with dielectric material including liquid crystal whose refractive index can be controlled by suitable application of voltage across the gap.