US Patent 6980365 Diffractive lens optical design

An optical system for use in a head-mounted display is provided which includes a microdisplay (4) and a magnifier (10) for producing a magnified image of the microdisplay for viewing by a human eye. The magnifier (10) includes a diffractive surface and has in order: a first element (1) having a first surface (S1) which is convex in the direction of the long conjugate, a block (3) of optical material, and a second element (2) having a second surface (S2) which is convex in the direction of the short conjugate. The first surface (S1) is preferably the diffractive surface. The magnifier provides a long eye relief, a large exit pupil, and a large field of view with a minimum of components.