Design of diffractive waveguide near eye display system with exit pupil expansion

In this paper, a two-dimensional diffractive optical waveguide with exit pupil expansion (EPE) is designed. By adding an extended grating between the in-coupling grating and the out-coupling grating, the optical path is redirected so that the exit pupil expansion can be realized in both horizontal and vertical directions, and then the pupil box can be enlarged. The projection collimation optical system is designed, which has the characteristics of small volume and compact structure. Combined with rigorous coupled wave analysis (RCWA), non-sequential ray tracing is used to optimize the grating region to achieve high image brightness uniformity. The results show that the designed EPE diffractive waveguide can achieve a large exit pupil range of 14mm×12mm, the diagonal field of view of the waveguide is 30°, the exit pupil distance is 20mm, and the image brightness in the exit pupil area is uniform.