Focus-free head-mounted display using pinhole and retroreflector film

We propose a focus-free retinal projection system, which is composed of a display device without coherent light, a pinhole, and a retroreflector film. By virtue of the retroreflector film as an image conjugator, a pinhole conjugate is formed as a small exit pupil at the center of eye pupil, which enables focus-free retinal imaging regardless of focal length of eye lens. This focus-free property of the proposed system addresses accommodation-vergence mismatch of three-dimensional augmented reality display system. We perform the experiments to prove the focus-free property of our proposed system.