Method for Compensating Aberrations of a Virtual Image Formed by an Augmented Reality Display Based on a Cylindrical Diffractive Waveguide

Abstract

To date, planar waveguides are under development for augmented reality systems with waveguide combiners. The next step of their development is the transition to curved waveguides, which could make the combiners more ergonomic. In the present work, a method has been developed that makes it possible to minimize aberrations of a virtual image during its in-coupling to and out-coupling from a cylindrical waveguide. The method is based on the use of in-coupling and out-coupling diffractive optical elements (DOE) with a variable grating period, which provide virtual image pre-aberration when radiation is in-coupled into the waveguide and compensation of the waveguide curvature at the out-coupling. Analytical laws are derived for the period variation of the in-coupling and out-coupling DOEs for an arbitrary curvature of a cylindrical waveguide. These dependences were optimized to minimize virtual image aberrations when using a radiation source with finite dimensions. Samples of cylindrical concentric PMMA waveguides with a curvature radius of 150 mm and in-coupling/out-coupling holographic optical elements (HOEs) have been created. The transmission of test monochrome virtual images through these waveguides without doubling and breaks in the field of view has been experimentally demonstrated.