Exit pupil replication using uniformized high-order diffractions for eyebox expansion in holographic near-eye displays

초록

We propose a passive pupil replication method for expanding the eyebox in holographic near-eye displays (HNEDs) by leveraging the balanced high-order diffractions of a spatial light modulator (SLM) under spherical divergent wave illumination. Unlike existing passive replication approaches that require additional optical elements, our method embeds a digitally encoded blazed two-dimensional (2D) grating and spherical lens phase profile directly into the pre-compensated hologram pattern on the SLM. This system design generates a 2D array of spatially separated, uniformized diffraction orders that carry identical image information with uniform intensity, while suppressing zeroth-order diffraction artifacts. These structured diffraction orders are angularly separated at given propagation distance and are mapped into multiple pupil replicas using a custom-fabricated segmented mirror-array holographic optical element (HOE) combiner. Fabricated with our developed holographic printer, the mirror-array HOE precisely aligns with the replicated viewpoints, enabling 2D pupil replication without sacrificing the field of view (FOV). The proposed prototype system achieves 2D exit pupil replication, offering a compact and efficient solution for eyebox expansion in holographic augmented reality near-eye display (AR-NED) applications.

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