Improvement in and relating to waveguides

摘要

A method for manufacturing a waveguide for a display apparatus comprising providing a planar optical waveguide part 24, depositing upon the optical waveguide part a fluid material (11, fig 11A) curable to form an optically transparent solid, impressing upon the fluid material an impression, such as by using stamper (40, 11B), defining an input diffraction grating region 28, and separately, an intermediate diffraction grating region 25 and an output diffraction grating region 27, curing (45, fig 11C) the impressed fluid material to solidify said impression. The apparent location of the input diffraction grating is located wholly within the geographical area of the intermediate grating though on opposite planar surfaces 24A & 24B of the optical waveguide part. The grating vectors of the input diffraction grating and the intermediate diffraction grating are oriented in different respective directions.