Disclosed is a four-dimensional (4D: 3D+time) multi-plane broadband imaging apparatus capable of recording 3D multi-plane and multi-colour images simultaneously. The apparatus comprises: one or more non-reentry quadratically distorted (NRQD) gratings (5) which can produce a focal length and a spatial position corresponding to each diffraction order, thus simultaneously transmitting wavefront information between multiple object/image planes (2) and a single image/object plane (7); a grism system (4) which can limit chromatically-induced lateral smearing by creating a collimated beam in which the spectral components are laterally displaced; a lens system (3) which is configured to adjust the optical path; and the optical detector(s) (6). In an optical system, the multiple object/image planes (2), the lens system (3), the grism system (4), the NRQD grating(s) (5), the optical detector(s) (6) and the single image/object plane (7) are located on the same optical axis (1). This simple, easy-to-use and compact apparatus can meet many different requirements and serve a large range of high throughput applications.

Long term optical memory includes a storage medium composed from an array of silicon nanoridges positioned onto the fused silica glass. The array has first and second polarization contrast corresponding to different phase of silicon. The first polarization contrast results from amorphous phase of silicon and the second polarization contrast results from crystalline phase of silicon. The first and second polarization states are spatially distributed over plurality of localized data areas of the storage medium.

In a multilayer optical disc having information layers conforming to a plurality of different optical disc standards, because the type of each information layer is not recorded in the other information layers, in read and write operations by a compatible optical disc device conforming to a plurality of optical disc standards, every time the information layer being accessed changes, it has been necessary to read the type of the information layer and select a method of generating a tracking error signal adapted to the type of information layer, so access has taken time. In order to solve the above problem, in the optical multilayer disc according to the present invention, having information layers conforming to a plurality of different optical disc standards, in an area in one of the information layers, information about the other information layers is recorded. The time required to access the other information layers can be reduced by using this information to select a tracking error signal generating method.

In a multilayer optical disc having information layers conforming to a plurality of different optical disc standards, because the type of each information layer is not recorded in the other information layers, in read and write operations by a compatible optical disc device conforming to a plurality of optical disc standards, every time the information layer being accessed changes, it has been necessary to read the type of the information layer and select a method of generating a tracking error signal adapted to the type of information layer, so access has taken time. In order to solve the above problem, in the optical multilayer disc according to the present invention, having information layers conforming to a plurality of different optical disc standards, in an area in one of the information layers, information about the other information layers is recorded. The time required to access the other information layers can be reduced by using this information to select a tracking error signal generating method.

The invention provides an optical film for improving image quality of a liquid crystal display comprising: a light directing structure layer, a first filling layer, a plurality of first diffraction gratings and a second filling layer. The light directing structure layer comprises a plurality of light directing micro structures, wherein the ratio of height to width of each light directing micro structure is in the range of 1.5 to 6. The first filling layer is disposed on the light directing structure layer, and the refractive index of the first filling layer and the light directing structure layer are different. The first diffraction gratings along with a first direction are formed on the first filling layer. The second filling layer is disposed on the first diffraction gratings and the refractive index of the second filling layer and the first diffraction gratings are different.

The invention provides an optical film for improving image quality of a liquid crystal display comprising: a light directing structure layer, a first filling layer, a plurality of first diffraction gratings and a second filling layer. The light directing structure layer comprises a plurality of light directing micro structures, wherein the ratio of height to width of each light directing micro structure is in the range of 1.5 to 6. The first filling layer is disposed on the light directing structure layer, and the refractive index of the first filling layer and the light directing structure layer are different. The first diffraction gratings along with a first direction are formed on the first filling layer. The second filling layer is disposed on the first diffraction gratings and the refractive index of the second filling layer and the first diffraction gratings are different.

A recording head has a waveguide core with an input end proximate an energy source at an input surface of the recording head. The waveguide core couples light from the energy source to a near-field transducer that heats a recording medium in response to the light. An input coupler extends along the waveguide core from the input end to a termination region that is away from the input end in a light propagation direction. The input coupler has a first refractive index between that of the waveguide core and a surrounding material. The input coupler is wider than the waveguide core and has a slanted edge at the termination region. The slanted edge crosses the waveguide core such that the input coupler narrows to a neck away from the waveguide core in a crosstrack direction.

Provided is a hologram recording medium that can achieve suppression of deterioration of the storage stability in an unexposed state. The hologram recording medium includes a base material and a photosensitive layer. The oxygen permeability of the base material measured in an environment at 23? C. and 0% RH is more than 0.1 cm.sup.3.Math.(m.sup.2.Math.day.Math.atm).sup.?1 and 10000 cm.sup.3.Math.(m.sup.2.Math.day.Math.atm).sup.?1 or less. The photosensitive layer contains a polymerizable compound, and the polymerizable compound contains a compound represented by a specific general formula.

A holographic data storage system comprises an emitter system, a holographic recording medium, and an input waveguide network formed of one or more multimode optical waveguides. The holographic recording medium has multiple recording regions, each optically coupled to a corresponding one of multiple out-coupling regions of the input waveguide network, the holographic data storage system arranged to persistently write data of an input beam, received at any one of the out-coupling regions, to the corresponding recording region. A controller is coupled to at least one of the emitter system and at least one controllable guiding element of the input waveguide network and controls at least one optical characteristic of the input beam or the at least one guiding element, so as to guide the input beam from an in-coupling region to any selected one of the multiple out-coupling regions. Similar waveguide networks are provided for carrying reference and output beams.

A holographic data storage system comprises an emitter system, a holographic recording medium, and an input waveguide network formed of one or more multimode optical waveguides. The holographic recording medium has multiple recording regions, each optically coupled to a corresponding one of multiple out-coupling regions of the input waveguide network, the holographic data storage system arranged to persistently write data of an input beam, received at any one of the out-coupling regions, to the corresponding recording region. A controller is coupled to at least one of the emitter system and at least one controllable guiding element of the input waveguide network and controls at least one optical characteristic of the input beam or the at least one guiding element, so as to guide the input beam from an in-coupling region to any selected one of the multiple out-coupling regions. Similar waveguide networks are provided for carrying reference and output beams.