Focus-free head-mounted display based on Maxwellian view using retroreflector film.

In this study, a focus-free retinal projection display based on a Maxwellian view was implemented. The display was constructed using simple and cost-effective passive components, such as a retroreflector film, beam splitter, and a pinhole. As a part of the system, the pinhole and display serve as a pinhole projector, which projects images through a small exit pupil. The retroreflector film and the beam splitter form the conjugate image of the pinhole near an observer. By locating the center of the crystalline lens of an eye at the conjugate pinhole, the projected images are focused on the retina and are seldomly changed by the accommodative response of the lens. For the practical implementation of the system, a collimating lens was used as an imaging lens combined with a pinhole. The point spread function of the system was derived to theoretically demonstrate that the system exhibits focus-free features at accommodation distances of 0.25, 0.5, and 1 m. The experiments conducted to demonstrate the feasibility of the system are presented under the same accommodation condition as the analysis.