Light sheets for continuous-depth holography and three-dimensional volumetric displays

Projecting high-quality three-dimensional (3D) scenes via computer-generated holography is a sought-after goal for virtual and augmented reality, human–computer interaction and interactive learning. Three-dimensional objects are usually constructed from a single hologram by cascading a stack of two-dimensional (2D) scenes along the optical path and perpendicular to it. The spatial separation between those scenes, however, is fundamentally constrained by the numerical aperture of the hologram, limiting the axial resolution and depth perception of the generated 3D image. Here we propose a new class of hologram that instead projects a desired scene onto 2D sheets oriented perpendicular to the plane of the display screen, thus enabling continuous reconstruction of the object along the optical path. To achieve this, we decompose the target scene into threads of light—arrays of non-diffracting pencil-like beams whose envelopes can be locally structured along the propagation direction at will. Using a spatial light modulator, we project 2D scenes onto the plane normal to the hologram and by stacking multiple 2D sheets in parallel we construct 3D objects with high fidelity and low crosstalk. Computer-generated holography of this kind opens new routes to realistic 3D holography and can be deployed in wearable smart glasses, portable devices and wide-angle volumetric displays.