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.

According to examples, a phase plate may include a transparent substrate and a photopolymer layer attached to the transparent substrate. The photopolymer layer may adjust a backlight via a phase adjustment and focusing. The phase plate may focus a plurality of red, green, and blue components of the backlight onto respective red, green, and blue subpixels of a thin-film-transistor (TFT) layer deposited thereon. A distance between the photopolymer layer of the phase plate and the plurality of red, green, and blue subpixels of the thin-film-transistor (TFT) layer may be in a range from about 200 μm to about 500 μm. In some examples, the phase plate may be part of a liquid crystal display (LCD) apparatus along with a red, green, blue (RGB) laser to provide backlight; a grating light guide to transmit the backlight; and a liquid crystal display (LCD) layer on the thin-film-transistor (TFT) layer.

A device includes a display configured to generate an image light. The device also includes a waveguide optically coupled with the display and configured to guide the image light to an exit pupil of the device. The waveguide includes a grating including a birefringent material, and a birefringence of the grating is configured to increase along a pupil-expanding direction of the device.

The apertures typically used for hologram recording create unwanted secondary holograms by diffracting light. Aperture-free hologram recording eliminates these unwanted secondary holograms. Aperture-free hologram recording includes applying a mask to the holographic recording medium. The mask controls the size of the recorded hologram like an aperture but does not create unwanted secondary holograms. Hologram fringes are only present in the desired recording area and a thin boundary region. The mask may be present during recording, or the mask may be used to pre-bleach the holographic recording medium. Pre-bleaching the holographic recording medium renders a portion of the holographic recording medium insensitive to light, the hologram is recorded in the light-sensitive portions of the holographic recording medium.

To provide a compound that is capable of improving the function of an organic material.

The present technology provides a compound represented by the following general formula (1).

##STR00001##

In the general formula (1), X.sup.1 represents an oxygen atom, a nitrogen atom, a phosphorus atom, a carbon atom, or a silicon atom.

Y.sup.1 and Y.sup.2 each represent a benzene ring or a naphthalene ring, and both Y.sup.1 and Y.sup.2 do not represent benzene rings.

R.sup.1 to R.sup.3 each represent a hydrogen or a substituent group represented by *—Z.sup.1(R.sup.4).sub.d (* represents a bonding site).

Z.sup.1 represents a single bond, a saturated hydrocarbon group having a valence of 2 or higher, or an unsaturated hydrocarbon group having a valence of 2 or higher, the saturated hydrocarbon group or the unsaturated hydrocarbon group optionally having an ether bond and/or a thioether bond.

R.sup.4 represents a hydrogen or a polymerizable substituent group.

A method of recording multiple holograms into a holographic recording medium includes exposing the medium to a first light to cause changes in a first refractive index of at least a portion of a first layer of the medium to write a first hologram in the first layer without changing a second refractive index of a second layer of the recording medium. The method also includes exposing the medium to a second light to cause changes in a second refractive index of at least a portion of the second layer to write a second hologram in the second layer. The first layer may include a first photo-polymerizable composition polymerizable by the first light, and the second layer may include a second photo-polymerizable composition polymerizable by the second light and not polymerizable by the first light.

Provided is a photopolymer composition for hologram recording comprising: a polymer matrix or a precursor thereof; a dye including a compound of the following Chemical Formula 1; a photoreactive monomer; and a photoinitiator, ##STR00001##

The apertures typically used for hologram recording create unwanted secondary holograms by diffracting light. Aperture-free hologram recording eliminates these unwanted secondary holograms. Aperture-free hologram recording includes applying a mask to the holographic recording medium. The mask controls the size of the recorded hologram like an aperture but does not create unwanted secondary holograms. Hologram fringes are only present in the desired recording area and a thin boundary region. The mask may be present during recording, or the mask may be used to pre-bleach the holographic recording medium. Pre-bleaching the holographic recording medium renders a portion of the holographic recording medium insensitive to light, the hologram is recorded in the light-sensitive portions of the holographic recording medium.

To provide a photosensitive composition capable of further improving diffraction characteristics.

The present technology provides a photosensitive composition including: at least a compound represented by the following general formula (1); a binder resin; and a photoinitiator.

##STR00001##

In the general formula (1), X.sup.1 represents an oxygen atom, a nitrogen atom, a phosphorus atom, a caron atom, or a silicon atom.

Y.sup.1 and Y.sup.2 each represent a benzene ring or a naphthalene ring, and both Y.sup.1 and Y.sup.2 do not represent benzene rings.

R.sup.1 to R.sup.3 each represent a hydrogen or a substituent group represented by *—Z.sup.1(R.sup.4).sub.d (* represents a bonding site).

Z.sup.1 represents a single bond, a saturated hydrocarbon group having a valence of 2 or higher, or an unsaturated hydrocarbon group having a valence of 2 or higher, and the saturated hydrocarbon group or the unsaturated hydrocarbon group may have an ether bond and/or a thioether bond.

R.sup.4 represents a hydrogen or a polymerizable substituent group.

A holographic recording medium composition contains an isocyanate group-containing compound (component (a-1)), an isocyanate-reactive functional group-containing compound (component (b-1)), a polymerizable monomer (component (c-1)), a photopolymerization initiator (component (d-1)), and a stable nitroxyl radical group-containing compound (component (e-1)). A ratio of the total weight of a propylene glycol unit and a tetramethylene glycol unit that are contained in the component (b-1) to the total weight of the component (a-1) and the component (b-1) is 30% or less.