Patent attributes
A HMD includes an electronic display and a pancake lens block. The pancake lens block includes a back curved optical element and a front curved optical element. Light propagating through the pancake lens block undergoes multiple reflections and to mitigate parasitic reflections, there are no air gaps between optical elements of the pancake lens block. A hybrid film that operates as a waveplate surface and a mirrored surface can be placed between the front curved optical element and the back curved optical element. A wide FOV can be obtained by making the coupling surfaces of the front optical element and the back optical element to be based on a convex cylindrical surface profile and a concave cylindrical surface profile, with the axis of the cylinder surface in a vertical direction for a user wearing the HMD.
