High brightness see-through head-mounted display

A head mounted display, comprising:

• a display providing an image to a lens to correct for any aberrations in the image and further projecting the image;
• a first prism, receiving the image, comprising at least three surfaces, a first surface, a second surface, and a third surface wherein the first surface is a diffractive surface diffracting the image to the second surface, the second surface is a total internal reflective surface reflecting the image to the third surface and the third surface is a reflective surface reflecting the image to a user of the head mounted display;
• and
• a second prism, the first prism and the second prism made of a polycarbonate material, attached to the first prism wherein the second prism is see through so that the user may see the image simultaneously with an external scene.

An image display apparatus, comprising:

• an image display device displaying an image;
• an optical system for providing the image displayed by the image display device to an observer wherein the optical system has at least three surfaces, a first surface is a diffracting surface, a second surface is a reflecting surface, and a third surface which is a reflecting surface facing the second surface;
• and
• wherein the optical system, made of a lightweight polymeric material, is arranged such that light rays emitted from the image display device pass through the first surface and are internally reflected by the second surface and further internally reflected by the third surface and the reflected light rays pass through the second surface and are led to the observer.