Optical device, head mounted display, assembling method for the same, holographic diffraction grating, display device, and alignment device

摘要

In some embodiments, a head mounted display is provided, comprising a light guide, at least first and second diffraction gratings, alignment marks A1 and B1 associated with the first diffraction grating, and alignment marks A2 and B2 associated with the second diffraction grating. The first diffraction grating may be disposed on a first surface of the light guide, the first surface facing away from a light input. The second diffraction grating may be disposed on a second surface of the light guide, the second surface facing towards the light input. The second diffraction grating may be adapted to diffract at least some of the light input into the light guide, and the first diffraction grating may be adapted to diffract at least some light transmitted through the light guide back into the light guide.