An advance in ultra-high-resolution optical imaging has been achieved by the introduction of iterative high-resolution image-building algorithms to incoherent holography. A recorded FINCH hologram is used as the basis of a method in which a high resolution image is built using detailed knowledge of the point spread functions of the FINCH hologram or reconstructed image, and then iteratively improved by successive algorithm generations of comparison to the recorded FINCH hologram and alteration of the high resolution image.

A totagram is produced by an iterative spectral phase recovery process resulting in complete information recovery using special masks, without a reference beam. Using these special masking systems reduce computation time, number of masks, and number of iterations. The special masking system is (1) a unity mask together with one or more bipolar binary masks with elements equal to 1 and −1, or (2) a unity mask together with one or more phase masks, or (3) a unity mask together with one pair of masks or more than one pair of masks having binary amplitudes of 0's and 1's, in which the masks in the pair are complementary to each other with respect to amplitude, or (4) one or more pairs of complementary masks with binary amplitudes of 0's and 1's without a unity mask.

There is provided a method of projection using an optical element (502,602) having spatially variant optical power. The method comprises combining Fourier domain data representative of a 2D image with Fourier domain data having a first lensing effect (604a) to produce first holographic data. Light is spatially modulated (504,603a) with the first holographic data to form a first spatially modulated light beam. The first spatially modulated light beam is redirected using the optical element (502,602) by illuminating a first region (607) of the optical element (602) with the first spatially modulated beam. The first lensing effect (604a) compensates for the optical power of the optical element in the first region (607). Advantageous embodiments relate to a head-up display for a vehicle using the vehicle windscreen (502,602) as an optical element to redirect light to the viewer (505,609).

A holographic display apparatus capable of providing an expanded viewing window and a display method are provided. The holographic display apparatus includes an image processor configured to provide computer generated hologram (CGH) data to a spatial light modulator, wherein the image processor is further configured to generate a hologram data array comprising information of the holographic image to be reproduced at the first resolution or a resolution less than the first resolution, perform an off-axis phase computation on the hologram data array at the second resolution, and then, generate the CHG data at the first resolution.

The goal of computer generated holography (CGH) is to synthesize custom illumination patterns by shaping the wavefront of a coherent light beam. Existing algorithms for CGH rely on iterative optimization with a fundamental trade-off between hologram fidelity and computation speed, making them inadequate for high-speed holography applications such as optogenetic photostimulation, optical trapping, or virtual reality displays. We propose a new algorithm, DeepCGH, that relies on a convolutional neural network to eliminate iterative exploration and rapidly synthesize high resolution holograms with fixed computational complexity. DeepCGH is an unsupervised model which can be tailored for specific tasks with customizable training data sets and an explicit cost function. Results show that our method computes 3D holograms at record speeds and with better accuracy than existing techniques.

Dual or multi-modulation display system are disclosed that comprise projector systems with at least one modulator that may employ non-mechanical beam steering modulation. Many embodiments disclosed herein employ a non-mechanical beam steering and/or polarizer to provide for a highlights modulator.

There is provided a method of projection using an optical element (502,602) having spatially variant optical power. The method comprises combining Fourier domain data representative of a 2D image with Fourier domain data having a first lensing effect (604a) to produce first holographic data. Light is spatially modulated (504,603a) with the first holographic data to form a first spatially modulated light beam. The first spatially modulated light beam is redirected using the optical element (502,602) by illuminating a first region (607) of the optical element (602) with the first spatially modulated beam. The first lensing effect (604a) compensates for the optical power of the optical element in the first region (607). Advantageous embodiments relate to a head-up display for a vehicle using the vehicle windscreen (502,602) as an optical element to redirect light to the viewer (505,609).

A method for encoding complex-valued signals of a computer-generated hologram into a phase-modulating optical element for the reconstruction of a three-dimensional object, and to a computer program product for encoding complex-valued signals of a computer-generated hologram, and to a holographic display for the reconstruction of a three-dimensional object. The object is to reduce the effort on encoding a complex-valued spatial distribution by an iteration method on the basis of phase encoding, so that the computer-generated hologram resulting therefrom can be represented more rapidly and with the same or an improved reconstruction quality. In particular, the convergence during the iterative optimization is intended to be accelerated. This is achieved by a method in which degrees of freedom of the hologram plane as well as the reconstruction plane are used for optimizing the iteration method for rapid convergence and maximization of the diffraction efficiency in the signal range.

There is provided a holographic projector comprising a reflective liquid crystal display device. The reflective liquid crystal display device comprises a light-modulating layer between a first substrate and a second substrate substantially parallel to the first substrate. The light-modulating layer comprises planar-aligned nematic liquid crystals having positive dielectric anisotropy. The first substrate is substantially transparent and comprises a first alignment layer arranged to impart a first pre-tilt angle θ.sub.l on liquid crystals proximate the first substrate, wherein θ.sub.1>5°. The second substrate is substantially reflective and comprises a second alignment layer arranged to impart a second pre-tilt angle Θ.sub.2 on liquid crystals proximate the second substrate, wherein θ.sub.2>5°. The reflective liquid crystal display device further comprises a plurality of pixels defined on the light-modulating layer having a pixel repeat distance x, wherein x≤10 μm. The distance d between inside faces of the first substrate and second substrate satisfies 0.5 μm≤d≤3 μm, and the birefringence of the liquid crystal Δη≥0.20. The holographic projector further comprises a display driver arranged to drive the reflective liquid crystal display device to display a hologram by independently-driving each pixel at a respective modulation level selected from a plurality of modulation levels having a phase modulation value.

A holographic display apparatus capable of providing an expanded viewing window and a display method are provided. The holographic display apparatus includes an image processor configured to provide computer generated hologram (CGH) data to a spatial light modulator, wherein the image processor is further configured to generate a hologram data array comprising information of the holographic image to be reproduced at the first resolution or a resolution less than the first resolution, perform an off-axis phase computation on the hologram data array at the second resolution, and then, generate the CHG data at the first resolution.