Design of a uniform-illumination binocular waveguide display with diffraction gratings and freeform optics

Uniform illuminance over the expanded exit pupil is an important requirement for waveguide display systems with a wide field of view (FOV). To address this issue, we develop a monochromatic binocular waveguide display in this paper. Two surface-relief diffraction gratings are designed as in-couplers and out-couplers. The parameters of the gratings are optimized to achieve uniform diffraction efficiency distributions over a broad angular range. The grating couplers enable the system to realize a diagonal FOV of 40°. A freeform surface prism is designed as the projection optics. The diameters of the two exit pupils are 12 mm in the expanding direction at an eye relief of 19 mm.