A photoreactive liquid crystal composition containing (A) a photoreactive polymer liquid crystal which includes a photoreactive side chain in which at least one type of reaction selected from (A-1) photocrosslinking and (A-2) photoisomerization occurs, and (B) a low molecular weight liquid crystal. An optical element or display element is formed having a liquid crystal cell including the photoreactive liquid crystal composition.

An interference structure having a nanovoided hologram material is described. The nanovoided hologram material may have an index of refraction difference of approximately 0.4. The interference structure may include about 10% to 90% nanovoids by volume. The interference structure may be formed using a mixture of a monomer, an initiator, and solvent. The mixture may be disposed on a substrate and irradiated with two sources of light spaced apart from each other and shining on the same region of the mixture to generate an interference pattern in the mixture, leading to the selective polymerization of regions of the mixture where there is constructive interference of light. Various other devices, methods, and systems are also disclosed.

Systems and methods for fabricating optical elements in accordance with various embodiments of the invention are illustrated. One embodiment includes a method for fabricating an optical element, the method including providing a first optical substrate, depositing a first layer of a first optical recording material onto the first optical substrate, applying an optical exposure process to the first layer to form a first optical structure, temporarily erasing the first optical structure, depositing a second layer of a second optical recording material, and applying an optical exposure process to the second layer to form a second optical structure, wherein the optical exposure process includes using at least one light beam traversing the first layer.

Various embodiments of this disclosure relate to a piecewise varying rolled K-vector grating structure including: a first grating section containing a grating with a first K-vector, a second grating section containing a grating with a second K-vector; and a first boundary region positioned between the first grating section and the second grating section. The first boundary region is a multiplexed grating region including both the first K-vector and the second K-vector. Further disclosed is a method for recording such a grating structure utilizing a holographic recording process. Providing a multiplexed grating in the first boundary region may largely remove line exposure artifacts between adjacent sections of the P-RKV grating.

Disclosed are a holographic writing method and apparatus capable of re-writing (updating) holographic information and quickly writing the holographic information with high efficiency. In an embodiment, a holographic writing method for writing holographic information by emitting a beam at a holographic recording medium containing a photo-responsable polymer material having photoisomerization characteristics that change a molecular structure thereof by absorbing light energy, writes the holographic information by using a writing wavelength different from a maximum absorption wavelength in a light absorption spectrum of photoisomer molecule structures of the holographic recording medium. The maximum absorption wavelength is a wavelength at which light absorption rate is maximum in the light absorption spectrum. A difference between the light absorption rates of the photoisomer molecule structures at the writing wavelength is less than a difference between the light absorption rates of the photoisomer molecule structures at the maximum absorption wavelength.

A system includes a laser emitting a laser beam, a beam expander expanding the laser beam, a beam splitter prism splitting the expanded laser beam into first and second split light beams, a liquid crystal box containing polymer-dispersed liquid crystal, first and second reflectors reflecting the first and second split light beams to the liquid crystal box, respectively, and an attenuator arranged on an optical path between the beam expander and the liquid crystal box. The attenuator gradually attenuates at least one of the laser beam, the expanded laser beam, the first split light beam, or the second split light beam along a first set curve. The first split light beam and the second split light beam form interference fringes at the liquid crystal box to expose the polymer-dispersed liquid crystal to form a polymer-dispersed liquid crystal holographic grating having a diffraction efficiency decreasing along a second set curve.

A method for producing holograms with a multiplicity of holographic prescriptions from a single master is provided. A multiplicity of holographic substrates each containing a first hologram is stacked on a second holographic recording medium substrate. The first hologram is designed to diffract light from a first direction into a second direction. When expose to illumination from the first direction zero order and diffracted light from each first hologram interfere in the second holographic recording medium substrate forming a second hologram. The second hologram is then copied into a third holographic recording medium substrate to provide the final copy hologram.

Techniques disclosed herein relate to modifying refractive index modulation in a holographic optical element, such as a holographic grating. According to certain embodiments, a holographic optical element or apodized grating includes a polymer layer comprising a first region characterized by a first refractive index and a second region characterized by a second refractive index. The holographic optical element or apodized grating includes a plurality of nanoparticles dispersed in the polymer layer. The nanoparticles have a higher concentration in either the first region or the second region. In some embodiments, the nanoparticles may be configured to increase the refractive index modulation. In some embodiments, the nanoparticles may be configured to apodize the grating by decreasing the refractive index modulation proximate to sides of the grating. The refractive index may be modulated by applying a monomer reservoir buffer layer to the polymer layer, either before or after hologram fabrication.

A light projection apparatus is provided comprising: a source of light; a switchable grating on a first substrate; and a diffractive optical element. Light is diffracted at least once by the switchable grating and is diffracted at least once by the DOE.

Typical waveguides rely on total internal reflection between the outer surfaces of substrates, which can make them highly susceptible to beam misalignment caused by nonplanarity of the substrates. In the manufacturing of the glass sheets commonly used for substrates, ripples can occur during the stretching and drawing of glass as it emerges from a furnace. Although glass manufacturers try to minimize ripples using predictions from mathematical models, it is difficult to totally eradicate the problem from the glass manufacturing process. Typically, these beam misalignments manifest themselves as image distortions and non-uniformities in the output illumination from the waveguide. Many embodiments of the invention are directed toward optically efficient, low cost solutions to the problem of controlling output image quality in waveguides manufactured using commercially available substrate glass and to the problem of compensating the image distortions and non-uniformity of curved waveguides.