Metasurfaces, as the ultrathin version of metamaterials, have caught growing attention due to their superior capability in controlling the phase, amplitude and polarization states of light. Among various types of metasurfaces, geometric metasurface that encodes a geometric or Pancharatnam-Berry phase into the orientation angle of the constituent meta-atoms has shown great potential in controlling light in both linear and nonlinear optical regimes. The robust and dispersionless nature of the geometric phase simplifies the wave manipulation tremendously. Benefitting from the continuous phase control, metasurface holography has exhibited advantages over conventional depth controlled holography with discretized phase levels. Here we report on spin and wavelength multiplexed nonlinear metasurface holography, which allows construction of multiple target holographic images carried independently by the fundamental and harmonic generation waves of different spins. The nonlinear holograms provide independent, nondispersive and crosstalk-free post-selective channels for holographic multiplexing and multidimensional optical data storages, anti-counterfeiting, and optical encryption.

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Spin and wavelength multiplexed nonlinear metasurface holography.

There is provided an information processing device including a display section configured to display a first object in a virtual three-dimensional space having a depth direction of a display screen, an operation section configured to acquire an operation for moving the first object in at least the depth direction, and a controller configured to move the first object on the display screen in accordance with the acquired operation, to execute, when a region of the first object overlaps a first overlap determination region, a first process to one or both of the first and second objects, and to execute, when the region of the first object overlaps a second overlap determination region, a second process to one or both of the first and second objects. The first overlap determination region may be a region obtained by extending the second overlap determination region in at least the depth direction.

Information processing device, information processing method, and program

Layer-based method has been proposed as an efficient approach to calculate holograms for holographic image display. This paper further improves its calculation speed and depth cues quality by introducing three different techniques, an improved coding scheme, a multilayer depth- fused 3D method and a fraction method. As a result the total computation time is reduced more than 4 times, and holographic images with accommodation cue are calculated in real time to interactions with the displayed image in a proof-of-concept setting of head-mounted holographic displays.

Improved layer-based method for rapid hologram generation and real-time interactive holographic display applications

The multiplexing encoding method is proposed and demonstrated for reconstructing colorful images accurately by using single phase-only spatial light modulator (SLM). It will encode the light waves at different wavelengths into one pure-phase hologram at the same time based on the analytic formulas. The three-dimensional (3D) images can be reconstructed clearly when the light waves at different wavelengths are incident into the encoding hologram. Numerical simulations and optical experiments for 2D and 3D colorful images are performed. The results show that the colorful reconstructed images with high quality are achieved successfully. The proposed multiplexing method is a simple and fast encoding approach and the size of the system is small and compact. It is expected to be used for realizing full-color 3D holographic display in future.

Multiplexing encoding method for full-color dynamic 3D holographic display.

Dynamic holographic three-dimensional (3-D) display, which features reconstructing 3-D images with full depth cues has great potential in various fields such as medical, and military industries obtained a broad attention in the last decades. Combing parallel computation techniques, hologram synthesis algorithms are capable of calculating diffraction and interference pattern dynamically or even in real-time manner. In addition, the development of various types of optical modulators including liquid crystal (LC)-based, opto-acoustic-typed, digital micromirror devices (DMDs), and opto–opto materials made it possible that device can load and display such holographic patterns dynamically. In accordance with the progress of algorithms and modulators, we can expect that dynamic holographic 3-D display will be able to reconstruct 3-D images with real-time refresh rate, full color, wide viewing angle, and large image size, and the system will be commercialized in a near future.

A Review of Dynamic Holographic Three-Dimensional Display: Algorithms, Devices, and Systems

A fast algorithm with low memory usage is proposed to generate the hologram for full-color 3D display based on a compressed look-up table (C-LUT). The C-LUT is described and built to reduce the memory usage and speed up the calculation of the computer-generated hologram (CGH). Numerical simulations and optical experiments are performed to confirm this method, and several other algorithms are compared. The results show that the memory usage of the C-LUT is kept low when number of depth layers of the 3D object is increased, and the time for building the C-LUT is independent of the number of depth layers of the 3D object. The algorithm based on C-LUT is an efficient method for saving memory usage and calculation time, and it is expected that it could be used for realizing real-time and full-color 3D holographic display in the future.

Reducing the memory usage for effective computer-generated hologram calculation using compressed look-up table in full-color holographic display.

The invention provides a method for calculating occlusion relations among holographic three-dimensional display objects. A vertical projection process is implemented on different sampling regions in a hologram, and occlusion information corresponding to all sub-holograms is eliminated; a reverse vertical projection process is used for obtaining undistorted three-dimensional lattice data on original object space, and amplitude distribution diagrams, corresponding to the data, of the holographic planar sampling regions are calculated to finally fit a hologram which has the characteristic of eliminating the occlusion. The calculation time for the hologram is not prolonged in the whole calculation process, the method is simple and practicable, and the correct occlusion relations among the objects can be obtained.

Qing Zhao

Papers

Reducing the memory usage for effective computer-generated hologram calculation using compressed look-up table in full-color holographic display.

Method for calculating occlusion relations among holographic three-dimensional display objects