A display panel (1) comprising a body of optical material, the body having at least one optical image recorded therein in an encoded manner, wherein the image is selectively reconstructable and viewable (5, 6, 7) by illuminating the panel (1) using at least one light source (3a, 3b, 3c) under selected illumination conditions, wherein the image is reconstructable and viewable (5, 6, 7) such that at least one first optical property or parameter of the reconstructed image (e.g. its geometry, position in space, colour, its dynamic appearance) is selectable in value from amongst variable values of the at least one first optical property or parameter, or whose value is actively modifiable over time, as a function of or in dependence on the value of at least one second optical property or parameter of the illumination conditions of the at least one light source (e.g. its/their position(s) or spacing(s) relative to the panel (1), its/their colour, brightness/optical intensity, polarisation, direction of light ray propagation, application of a scanning technique to illuminate the panel (1)) which is selectable from amongst variable values thereof or which is actively modifiable in value over time.

A holographic display system including a first spatial light modulator panel and a second spatial light modulator panel is provided. The first spatial light modulator panel is configured to receive a first light with a first color, and generate a first diffracted light with the first color. The second spatial light modulator panel is configured to receive a second light with a second color and a third light with a third color, and respectively generate a second diffracted light with the second color and a third diffracted light with the third color. The first color, the second color, and the third color are different colors, and the first diffracted light, the second diffracted light and the third diffracted light form holographic images. A method for generating holographic images is also provided.

A grating coupler may be fabricated by exposing a photopolymer layer to grating forming light for forming periodic refractive index variations in the photopolymer layer. The photopolymer layer may be exposed to apodization light for reducing an amplitude of the periodic refractive index variations in a spatially-selective manner. The apodization may also be achieved or facilitated by subjecting outer surface(s) of the photopolymer layer to a chemically reactive agent that causes the refractive index contrast to be reduced near the surface(s) of application. The apodized refractive index profile of the gratings facilitates the reduction of optical crosstalk between different gratings of the grating coupler.

A holographic security or identification device (10) comprises an object, or a flexible substrate (12) configured to be conformable to a desired, curved shape; and a plurality of structures (14) formed on or in the object to have a desired curved configuration, or formed in or associated with the substrate and arranged to adopt a desired curved configuration when the substrate is conformed to a desired shape, wherein the plurality of structures (14) are configured to receive light (20) of a selected at least one wavelength or range of wavelengths and to produce, using the received light, a desired holographic image (22) for security or identification purposes when in the desired configuration.

A method of manufacturing a full-color holographic optical element in a full-color holographic optical element manufacturing apparatus including a lens and a holographic recording medium located farther away than a focal length of the lens, the method including: allowing a signal beam including a mixture of laser beams having wavelengths of R (Red), G (Green), and B (Blue) to be incident on the lens; and recording a hologram in such a manner that a reference beam including a mixture of laser beams having wavelengths of R, G, and B is allowed to be incident on the holographic recording medium, wherein the holographic recording medium is configured with a single medium.

Various examples of out-of-plane multicolor waveguide holography systems, methods of manufacture, and methods of use are described herein. In some examples, a multicolor waveguide holography system includes a planar waveguide to convey optical radiation between a grating coupler and a metasurface hologram. The grating coupler may be configured to couple out-of-plane optical radiation of three different color incident at three different angles into the planar waveguide. The combined multicolor optical radiation may be conveyed by the waveguide to the metasurface hologram. The metasurface hologram may diffractively decouple the three colors of optical radiation for off-plane propagation to form a multicolor holographic image in free space.

An augmented reality display device (such as a head mounted device) includes a partially transparent and partially reflective lens, a laser light source, a radio frequency source, a display controller, an acousto-optical modulator, and a microelectromechanical (MEMS) device. The laser light source generates light. The radio frequency (RF) source generates a RF signal. The display controller generates a synchronization signal. The acousto-optical modulator receives at least a portion of the light, modulates the light based on the RF signal, and provides modulated light. The MEMS device receives the synchronization signal from the display controller and reflects the modulated light towards the partially transparent and partially reflective lens. The MEMS device determines a direction in which the modulated light reflects based on the synchronization signal and the partially transparent and partially reflective lens reflecting the modulated laser light towards an eye of a user of the augmented realty display device.

Techniques related to generating holographic images are discussed. Such techniques include application of a hybrid system including a pre-trained deep neural network and a subsequent iterative process using a suitable propagation model to generate diffraction pattern image data for a target holographic image such that the diffraction pattern image data is to generate a holographic image when implemented via a holographic display.

A label-free bio-aerosol sensing platform and method uses a field-portable and cost-effective device based on holographic microscopy and deep-learning, which screens bio-aerosols at a high throughput level. Two different deep neural networks are utilized to rapidly reconstruct the amplitude and phase images of the captured bio-aerosols, and to output particle information for each bio-aerosol that is imaged. This includes, a classification of the type or species of the particle, particle size, particle shape, particle thickness, or spatial feature(s) of the particle. The platform was validated using the label-free sensing of common bio-aerosol types, e.g., Bermuda grass pollen, oak tree pollen, ragweed pollen, Aspergillus spore, and Alternaria spore and achieved >94% classification accuracy. The label-free bio-aerosol platform, with its mobility and cost-effectiveness, will find several applications in indoor and outdoor air quality monitoring.

The layered generation of at least one volume grating in a recording medium by way of exposure, the recording medium having at least one photosensitive layer which is sensitized for a presettable wavelength of the exposure light. Each volume grating is generated in the recording medium by at least two wave fronts of coherent light capable of generating interference, the wave fronts being superposed in the recording medium at a presettable depth, at a presettable angle and with a presettable interference contrast. The depth and the thickness of the refractive index modulation and/or transparency modulation of a volume grating in the recording medium is controlled by depth-specific control of the spatial and/or temporal degree of coherence of the interfering wave fronts in the direction of light propagation.