Free-space combiner based on holographic mirrors for head-mounted displays.

The paper presents an augmented reality display based on the free-space combiner, consisting of two holographic mirrors: flat and spherical. A feature of such a system is a high-reflection coefficient of mirrors up to 90% for one wavelength and a high transmittance to the lumen up to 67% throughout the rest of the visible spectrum, unlike similar solutions implementing principles of polarization or dichroic beam splitting. The recording scheme and calculation of a separate flat holographic mirror and spherical holographic mirror are described. The proposed augmented reality display can provide multifocality, i.e., reproduction of virtual images at several distances, which demonstrates a certain perspective of this implementation in terms of compensation for the vergence accommodation conflict.