Abstract: A video display device is provided with a light source, a display element, and an eyepiece optical system (14). The light source emits light which has at least one emission peak wavelength and has a wavelength width including one emission peak wavelength. The display element modulates the light emitted from the light source and displays video. The eye-piece optical system (14) comprises a volume phase reflective HOE (23) with diffracts and reflects video light from the display element and leads the light to a viewing pupil. An HOE surface (23a) is divided into a plurality of flat surfaces (31, 32, 33) disposed so as to be recessed on the viewing pupil side, and the plurality of flat surfaces (31, 32, 33) are continuous so as to have a common ridge line at a boundary between the flat surfaces adjoining to each other.

Abstract: A video image display device (1) is provided with an ocular optical system (12) that guides video image light from a display element (11) to the pupil of an observer through an ocular prism (21) and at the same time guides ambient light to the pupil of the observer through the ocular prism (21). The eyepiece optical system (12) has reflection planes set in the ocular prism (21) that are provided with three or more planes to fold down three or more times an optical path for the video image light from the display element (11), wherein an HOE (23) is formed on at least one plane of the reflection planes. The video image display device (1) satisfies a conditional equation that properly prescribes the relationship between an incident range of the video image light incident on the HOE (23) formed plane in the ocular prism (21) and a display screen size of the display element (11).

Abstract: Light outputted from a laser light source (12) of an image generating section (11) is two-dimensionally deflected and permitted to perform scanning by means of a reflecting surface (13a) of a deflecting device (13), diffused by means of a diffusion unit (14), and then diffracted and reflected by an HOE (23) of an eyepiece optical system (4), and guided to an optical pupil (E). Deterioration of qualities of an observing image can be eliminated by setting the optical pupil (E) and the reflecting surface (13a) of the deflecting device (13) to have an optically conjugated positional relationship.

Abstract: A video display device is provided with a light source, a display element, and an eyepiece optical system (14). The light source emits light which has at least one emission peak wavelength and has a wavelength width including one emission peak wavelength. The display element modulates the light emitted from the light source and displays video. The eye-piece optical system (14) comprises a volume phase reflective HOE (23) with diffracts and reflects video light from the display element and leads the light to a viewing pupil. An HOE surface (23a) is divided into a plurality of flat surfaces (31, 32, 33) disposed so as to be recessed on the viewing pupil side, and the plurality of flat surfaces (31, 32, 33) are continuous so as to have a common ridge line at a boundary between the flat surfaces adjoining to each other.

Abstract: The light directed from a light source to a concave mirror and the light directed from a display device to an eyepiece optical system are intersected by each other in a layout. This allows the light source, the concave mirror, and the display device to be arranged in compactness adjacent to the eyepiece optical system without increasing the optical power of an illumination optical system. As the result, the apparatus can easily be minimized in the thickness or the overall size. A hologram optical element is provided where the relationship between the wavelength range ??1 at half of the diffraction efficiency of each of the three primary colors of the light in the hologram optical element and the wavelength range ??2 at half of the intensity of each of the three primary colors of the light emitted from the light source is defined by ??1 <??2.

Abstract: A volume-phase reflection hologram optical element is fabricated by exposing a hologram photosensitive material to two coherent light beams. One exposure light beam has an axis-asymmetric wavefront, and the other exposure light beam has focus points different in the optical axis direction (Z-direction) between on a plane (ZX-plane) including one of two directions (X- and Y-directions) mutually perpendicular on a sectional plane perpendicular to that light beam and on a plane (YZ-plane) including the other of those two directions. Thus, an image display apparatus is realized in which at the time of reproduction, the component of a predetermined wavelength of the image light diffraction-reflected by the hologram optical element is focused at positions different in the optical axis direction between on the ZX-plane and on the YZ-plane, offering different image viewing characteristics between in the X- and Y-directions.

Abstract: A total reflection surface and a holographic optical element (HOE) surface are formed on the same surface (S3) in an eyepiece prism (15). In this structure, a smaller reflection angle can be set at an HOE (16) compared to a structure with the surface formed separately, and the HOE surface of the surface (S3) can be set in the direction parallel to a surface (S2). Thus, even in a structure in which at least a portion of the light flux of the image light fully reflected by the surface (S3) is incident on an affixing region (R1) of a hologram photosensitive material (16a), that portion of the light can be prevented from falling incident on the optical pupil (E) as ghost light. Consequently, in order to prevent the generation of ghost light, an optical path margin no longer needs to be provided between the diffraction and reflection region of the HOE (16) and the total reflection region of the image light; and the eyepiece prism (15) can be thinned by that amount.

Abstract: A video image display device (1) is provided with an ocular optical system (12) that guides video image light from a display element (11) to the pupil of an observer through an ocular prism (21) and at the same time guides ambient light to the pupil of the observer through the ocular prism (21). The eyepiece optical system (12) has reflection planes set in the ocular prism (21) that are provided with three or more planes to fold down three or more times an optical path for the video image light from the display element (11), wherein an HOE (23) is formed on at least one plane of the reflection planes. The video image display device (1) satisfies a conditional equation that properly prescribes the relationship between an incident range of the video image light incident on the HOE (23) formed plane in the ocular prism (21) and a display screen size of the display element (11).

Abstract: Light outputted from a laser light source (12) of an image generating section (11) is two-dimensionally deflected and permitted to perform scanning by means of a reflecting surface (13a) of a deflecting device (13), diffused by means of a diffusion unit (14), and then diffracted and reflected by an HOE (23) of an eyepiece optical system (4), and guided to an optical pupil (E). Deterioration of qualities of an observing image can be eliminated by setting the optical pupil (E) and the reflecting surface (13a) of the deflecting device (13) to have an optically conjugated positional relationship.

Abstract: Information light modulated and emitted by a modulation element is led to a recording medium through a Fourier transform optical system and an optical path shifter. An interference image is recorded on the recording medium by interference of the information light and reference light. A deflection unit of the optical path shifter has a pair of prisms. Optical path of information light transmitted through the respective prisms are shifted in parallel in a direction perpendicular to an optical axis of the Fourier transform optical system. By rotating the deflection unit around the optical axis, it is possible to shift the optical path of the information light around the optical axis while shifting the optical path in the direction perpendicular to the optical axis. Therefore, it is unnecessary to perform complicated control and it is possible to multiply record an interference image accurately with an information recording apparatus having a simple structure.

Abstract: Variation of the wavelength of the light emitted from a light source is reduced by a wavelength variation reduction mechanism. Hence, wavelength deviation of the intensity peak of the light emitted from the light source from the diffraction-efficiency peak of a hologram optical element is reduced. Thus, even when a high-brightness light source is used, the light emitted therefrom can be diffracted with the hologram optical element efficiently. Moreover, the heat generated by the light source is efficiently rejected through the surface of a land portion of a flexible printed circuit, is then, via an insulating layer of the flexible printed circuit, efficiently absorbed through the surface of a heat absorbing member, and is then, via a shield conductor, led out of a casing, so as to be thereby expelled.

Abstract: A hologram optical element is formed on a substrate so as to make an optical device. The hologram optical element is formed in an area smaller than an irradiation area of a beam for reproduction such as image light or object light on the substrate. Supposing that the beam for reproduction is made of a center beam having intensity higher than 50% of center intensity and other peripheral beam, the hologram optical element is formed on the substrate in a size for diffracting only the center beam so that a flare or a ghost can be relieved without using additional optical elements such as a shading plate.

Abstract: The light directed from a light source to a concave mirror and the light directed from a display device to an eyepiece optical system are intersected by each other in a layout. This allows the light source, the concave mirror, and the display device to be arranged in compactness adjacent to the eyepiece optical system without increasing the optical power of an illumination optical system. As the result, the apparatus can easily be minimized in the thickness or the overall size. A hologram optical element is provided where the relationship between the wavelength range ??1 at half of the diffraction efficiency of each of the three primary colors of the light in the hologram optical element and the wavelength range ??2 at half of the intensity of each of the three primary colors of the light emitted from the light source is defined by ??1<??2.

Abstract: An arrangement of the invention includes a base block 16, a cylindrical cam 14, as a rotary member, which is rotatably supported on the base block 16, and includes a contact portion on an outer periphery thereof for outputting a rotating force, a drive gear 21, as an oscillatory ring, which includes a contact portion on an inner periphery thereof, and is oscillated on a plane perpendicular to a rotation axis of the cylindrical cam 14 in contact with the contact portion of the cylindrical cam 14, parallel springs 23 through 26, as a position retainer, for retaining the position of the drive gear 21, and three or more shape metal alloy actuators (SMA) wires 35 through 38, as expandable and contractible actuators, with both ends of the each SMA wire being fixed to the base block 16 for contact with the drive gear 21.

Abstract: A drive for operating a movable part with respect to a fixed part includes: a driving member having a linear shape and being made of a shape-memory alloy; and a crimp terminal for holding one end of the driving member at the fixed part or the movable part. At least a part to which the driving member is crimped in the crimp terminal is made of stainless steel.

Abstract: In an image display apparatus, two light sources emit illumination light having different wavelengths, with which a liquid crystal display device is illuminated. By modulating the illumination light, the liquid crystal display device produces a first and a second image light having different wavelengths. Two holographic optical elements respectively reflect the first and second image lights and direct them to the user's eye so that virtual images of the images represented by the first and second image lights are formed at different positions. As the light source from which to obtain the illumination light is switched between the two, the dioptric power with which to present an image is changed.

Abstract: A volume-phase reflection hologram optical element is fabricated by exposing a hologram photosensitive material to two coherent light beams. One exposure light beam has an axis-asymmetric wavefront, and the other exposure light beam has focus points different in the optical axis direction (Z-direction) between on a plane (ZX-plane) including one of two directions (X- and Y-directions) mutually perpendicular on a sectional plane perpendicular to that light beam and on a plane (YZ-plane) including the other of those two directions. Thus, an image display apparatus is realized in which at the time of reproduction, the component of a predetermined wavelength of the image light diffraction-reflected by the hologram optical element is focused at positions different in the optical axis direction between on the ZX-plane and on the YZ-plane, offering different image viewing characteristics between in the X- and Y-directions.

Abstract: As a result of the light from a plurality of point light sources located at an identical position being refracted at a surface of a color correction prism at the time of exposure, the chromatic aberration occurring as a result of the light (for example, image light) directed via a refractive surface of the optical system used at the time of reconstruction to the viewer's pupil being refracted at this refractive surface is corrected for. Moreover, at least two of another set of a plurality of point light sources are arranged at such positions as to provide angles of incidence commensurate with the deviation between them of the ratio between exposure wavelength and use wavelength.

Abstract: The light directed from a light source to a concave mirror and the light directed from a display device to an eyepiece optical system are intersected by each other in a layout. This allows the light source, the concave mirror, and the display device to be arranged in compactness adjacent to the eyepiece optical system without increasing the optical power of an illumination optical system. As the result, the apparatus can easily be minimized in the thickness or the overall size. A hologram optical element is provided where the relationship between the wavelength range ??1 at half of the diffraction efficiency of each of the three primary colors of the light in the hologram optical element and the wavelength range ??2 at half of the intensity of each of the three primary colors of the light emitted from the light source is defined by ??1<??2.

Abstract: Information light modulated and emitted by a modulation element is led to a recording medium through a Fourier transform optical system and an optical path shifter. An interference image is recorded on the recording medium by interference of the information light and reference light. A deflection unit of the optical path shifter has a pair of prisms. Optical path of information light transmitted through the respective prisms are shifted in parallel in a direction perpendicular to an optical axis of the Fourier transform optical system. By rotating the deflection unit around the optical axis, it is possible to shift the optical path of the information light around the optical axis while shifting the optical path in the direction perpendicular to the optical axis. Therefore, it is unnecessary to perform complicated control and it is possible to multiply record an interference image accurately with an information recording apparatus having a simple structure.