Design of projection-based augmented reality system using holographic screen display

Abstract

Holographic display elements (HOEs) with a high diffraction efficiency and size enlargement have been developed since 2019. To achieve high brightness and low haze, unprecedented optical systems have been proposed with a uniform chief ray angle of 0° in the x-section and 70° in the y-section of the HOEs. A 360° cylindrical holographic screen display (CHSD) was obtained by providing a large tilt to the surface shape near the optical axis. This was done using a first-order odd aspherical coefficient for the light flux from a refractive optical system (RO). A flat holographic screen display (FHSD) is a compact, high-performance display that uses three decentered and tilted freeform mirrors to route light flux from the RO in a ball-like form. Prototyping also proposes the possibility of an augmented reality system that takes advantage of the high transparency. The design for further miniaturization while maintaining optical performance was also discussed, in which the size of the first mirror was reduced by reducing the half-field angle of the RO to approximately 6°. Furthermore, by increasing the negative power of the second mirror, the small size could be maintained. The size of the last mirror was dependent on the screen size and could not be reduced. By laying down the posture of this mirror, we were able to halve the size reduction in the vertical direction. In this paper, lens designs for CHSDs and FHSDs are reported. The potential of this display is also discussed.