Compact noise-filtering volume gratings for holographic displays

A compact noise filtering method for holographic head-mounted displays (HMDs) is proposed. Conventionally, twin, DC and high-order noise from the spatial light modulators is filtered by a spatial stop filter with a 4-f system. Since the 4-f system requires a long optical path length, the noise filtering system usually occupies most of the volume in holographic displays. In the proposed method, only thin angular stop filters (ASFs) are used for noise filtering. The ASFs do not require a bulky 4-f system while performing the same function as the conventional method. The proposed method is verified experimentally. Our study provides an important solution for realization of compact holographic HMDs.