Abstract: A virtual image display device is provided which displays a two-dimensional image for viewing a virtual image in a magnified form by a virtual optical system. The virtual image display device includes an optical waveguide (13) to guide, by internal total reflection, parallel pencil groups meeting a condition of internal total reflection, a first reflection volume hologram grating (14) to diffract and reflect the parallel pencil groups incident upon the optical waveguide from outside and traveling in different directions as they are so as to meet the condition of internal total reflection inside the optical waveguide and a second reflection volume hologram grating (15) to project the parallel pencil groups guided by internal total reflection inside the optical waveguide as they are from the optical waveguide by diffraction and reflection thereof so as to depart from the condition of internal total reflection inside the optical waveguide.

Abstract: The present invention relates to an image display device in which a virtual image of an image display element is formed to display an image. The image display device includes a transmission type diffraction optical element (50) for diffracting exit lights from the image display element (20) and a reflection type optical element (70) having a positive optical power for reflecting the diffracted lights from the transmission type diffraction optical element (50). When the reflected lights reflected by the reflection type optical element (70) are incident again on the transmission type diffraction optical element (50), the transmission type diffraction optical element (50) diffracts the reflected lights with a diffraction efficiency lower than a diffraction efficiency for the exit lights from the image display element (20).

Abstract: An optical device includes a light guide plate, and first and second reflective volume hologram diffraction grating members. The first member has interference fringes extending from therewithin towards surfaces thereof and arranged at an equal pitch. Each interference fringe and each surface of the first member form an inclination angle therebetween. The first member has the following conditions. (a) In an outer region positioned farther away from the second member than a minimum inclination angle region having a minimum inclination angle, the inclination angles of the interference fringes increase with increasing distance from the minimum inclination angle region. (b) In an inner region positioned closer to the second member than the minimum inclination angle region, the inclination angles of the interference fringes include a maximum inclination angle in an inner area disposed adjacent to the minimum inclination angle region and decrease with increasing distance from the minimum inclination angle region.

Abstract: Disclosed is an image display apparatus for a viewer to view a two-dimensional image, demonstrated on an image display device, as an enlarged virtual image by a virtual-image optical system. The image display apparatus includes a prism (15), provided with a second planar optical surface (15c), arranged parallel to a first planar optical surface (15b) on a side towards an optical pupil (19), and with a reflective transmitting surface (16) for reflecting or transmitting image light incident from an incident optical surface (15a), which has an optical axis with an angle of tilt not less than 30 degrees and less than 90 degrees relative to a normal to the first planar optical surface or to the second planar optical surface, and on which is incident image light, demonstrated on an image display device (11) and relayed by a relaying optical system.

Abstract: There is provided an optical device including an optical waveguide upon which a group of parallel light beams different in traveling direction from each other are incident and from which the group of parallel light beams go out after propagated by repeated total reflection through it. The optical waveguide includes a first reflection-type volume hologram grating, and a second reflection-type volume hologram grating. The pitches of interference fringes on the hologram surfaces of the first and second reflection-type volume hologram gratings are equal to each other. In at least the second reflection-type volume hologram grating, the angle formed between the interference fringes and hologram surfaces are varied continuously or stepwise within the hologram in relation to the main incident light beam so as to meet the Bragg condition. Therefore, it is possible to reduce the unevenness of color and brightness due to angles of view.

Abstract: The present invention is directed to a transmission type laminated hologram optical element constituting an image display apparatus, wherein plural transmission type hologram optical elements (13), (14), (15) where diffraction acceptance incident angles are different from each other are laminated. The respective transmission type hologram optical elements are adapted so that outgoing angles with respect to center incident angles of respective diffraction acceptance incident angles at an arbitrary wavelength of the visible region are different from each other, whereby a diffraction acceptance angle of incident light can be broadened, light utilization efficiency is permitted to be high, and distance with respect to color pixels of the spatial light modulation element can be optimally set from viewpoints of light utilization efficiency.

Abstract: A virtual image display device is provided which displays a two-dimensional image for viewing a virtual image in a magnified form by a virtual optical system. The virtual image display device includes an optical waveguide (13) to guide, by internal total reflection, parallel pencil groups meeting a condition of internal total reflection, a first reflection volume hologram grating (14) to diffract and reflect the parallel pencil groups incident upon the optical waveguide from outside and traveling in different directions as they are so as to meet the condition of internal total reflection inside the optical waveguide and a second reflection volume hologram grating (15) to project the parallel pencil groups guided by internal total reflection inside the optical waveguide as they are from the optical waveguide by diffraction and reflection thereof so as to depart from the condition of internal total reflection inside the optical waveguide.

Abstract: This invention is an image display device for performing color display of an image using two spatial light modulators. The image display device has a first spatial light modulator (52) for modulating a first wavelength range component of illuminating light from an illuminating light source (10), dichroic mirrors (40), (41) for separating second and third wavelength range components of the illuminating light and condensing the respective wavelength range components, a second spatial light modulator (50) for modulating the second and third wavelength range components, and a dichroic mirror (60) for combining modulated light emitted from the first and second spatial light modulators (52), (50).

Abstract: The present invention relates to an image display device in which a virtual image of an image display element is formed to display an image. The image display device includes a transmission type diffraction optical element (50) for diffracting exit lights from the image display element (20) and a reflection type optical element (70) having a positive optical power for reflecting the diffracted lights from the transmission type diffraction optical element (50). When the reflected lights reflected by the reflection type optical element (70) are incident again on the transmission type diffraction optical element (50), the transmission type diffraction optical element (50) diffracts the reflected lights with a diffraction efficiency lower than a diffraction efficiency for the exit lights from the image display element (20).

Abstract: The present invention is directed to a transmission type laminated hologram optical element constituting an image display apparatus, wherein plural transmission type hologram optical elements (13), (14), (15) where diffraction acceptance incident angles are different from each other are laminated. The respective transmission type hologram optical elements are adapted so that outgoing angles with respect to center incident angles of respective diffraction acceptance incident angles at an arbitrary wavelength of the visible region are different from each other, whereby diffraction acceptance angle of incident light can be broadened, light utilization efficiency is permitted to be high, and distance with respect to color pixels of the spatial light modulation element can be optimally set from viewpoints of light utilization efficiency.

Abstract: This invention is an image display device for performing color display of an image using two spatial light modulators. The image display device has a first spatial light modulator (52) for modulating a first wavelength range component of illuminating light from an illuminating light source (10), dichroic mirrors (40), (41) for separating second and third wavelength range components of the illuminating light and condensing the respective wavelength range components, a second spatial light modulator (50) for modulating the second and third wavelength range components, and a dichroic mirror (60) for combining modulated light emitted from the first and second spatial light modulators (52), (50).

Abstract: An image display device including a polarization selective holographic optical device for diffracting illuminating light, and a reflection type spatial optical modulator for modulating the state of polarization of the illuminating light diffracted by the polarization selective holographic optical device is disclosed. The device includes a plurality of each of two areas of respectively different incidence polarization orientation dependencies of the refractive index, with the layers being layered sequentially alternately. An image display apparatus including the above image display device, a light source, an illuminating optical system and a projection optical system is also disclosed. With the present optical display device and optical display apparatus, the utilization efficiency of the illuminating light may be improved, while the device and the apparatus may be reduced in size and production cost, as uniformity and high contrast of the image displayed are achieved simultaneously.

Abstract: An image display device including a polarization selective holographic optical device for diffracting illuminating light, and a reflection type spatial optical modulator for modulating the state of polarization of the illuminating light diffracted by the polarization selective holographic optical device is disclosed. The device includes a plurality of each of two areas of respectively different incidence polarization orientation dependencies of the refractive index, with the layers being layered sequentially alternately. An image display apparatus including the above image display device, a light source, an illuminating optical system and a projection optical system is also disclosed. With the present optical display device and optical display apparatus, the utilization efficiency of the illuminating light may be improved, while the device and the apparatus may be reduced in size and production cost, as uniformity and high contrast of the image displayed are achieved simultaneously.

Abstract: The present invention relates to an image display device that is suitably applicable to, for example, a projector using an ultrahigh-pressure mercury lamp as a light source. In a light source of the present invention, main light is partially replaced with auxiliary light in a wavelength region in which the intensity of the main light is less than that of the auxiliary light. That is, the light source includes an illumination-light combining member that generates illumination light by strengthening the wavelength region of the emission spectrum of the main light with the auxiliary light. Accordingly, the loss of main light is satisfactorily reduced, and the light intensity in the wavelength region in which the intensity of the main light is insufficient is compensated for. Further, light emitted from the main light source formed of a lamp or the like is efficiently utilized, and a bright image can thereby be displayed with high color reproducibility.

Abstract: The present invention relates to an image display device that is suitably applicable to, for example, a projector using an ultrahigh-pressure mercury lamp as a light source. In a light source of the present invention, main light is partially replaced with auxiliary light in a wavelength region in which the intensity of the main light is less than that of the auxiliary light. That is, the light source includes an illumination-light combining member that generates illumination light by strengthening the wavelength region of the emission spectrum of the main light with the auxiliary light. Accordingly, the loss of main light is satisfactorily reduced, and the light intensity in the wavelength region in which the intensity of the main light is insufficient is compensated for. Further, light emitted from the main light source formed of a lamp or the like is efficiently utilized, and a bright image can thereby be displayed with high color reproducibility.

Abstract: There is provided a virtual image optical system which removes the noise caused by stray light, removes the aberration, and which can be implemented in a smaller size. The virtual image optical system includes a reflective spatial light modulator, an illuminating light source device, eyepiece optics, and a light source optical system. The light source optical system includes at least one beam splitter. The eyepiece optics include at least one beam splitter and reflector. An angle formed by a plane normal vector formed with respect to the reflector of the eyepiece optics and a plane normal vector formed with respect to the beam splitter is in the range of 136 degrees to 179 degrees.

Abstract: A recording disc for use with a disc recording and reproducing apparatus of the type having a disc chucking device which includes a spring biased, conically shaped centering member mounted coaxially on a drive spindle, wherein the disc includes a disc substrate contained in a cartridge and having a center hole which has a diameter smaller than a base diameter of the conically shaped centering member, an annular rib which depends from a lower surface of the disc substrate toward the disc chucking device for seating on a disc setting member and which enlarges the thickness of the disc substrate, in the direction of the axis of rotation of the spindle, around the periphery of the center hole so that the centering member can have a steeper slope compared to prior art centering members, and thereby provide more effective centering action, and yet when the disc substrate is supported by the annular rib on the disc setting member no part of the disc chucking device extends through the center hole of the disc substra

Abstract: In an optical system used for observing a virtual image, in which a Lippman volumetric hologram is used as a reflection type holographic optical element, the generation of aberration needs to be minimized to enable an optimum virtual image to be viewed. To this end, at least one optical element and the Lippman volumetric hologram 10 are provided for cooperating to form a virtual image of the display image on an image display device 6. The Lippman volumetric hologram 10 is contoured so that its curvature is in the same direction as the curvature of interference fringes operating for generating a refractive power in this Lippman volumetric hologram 10.

Abstract: A disc table employed in disc recording/reproducing apparatus employing, as a recording medium, a recording disc, such as an optical disc or a magneto-optical disc, on which information signals are pre-recorded or are to be recorded, is disclosed. The disc table includes a fitting member fitted from its distal end into a circular center aperture of the recording disc, a table section which is integrated to the fitting member at a proximal side of the fitting member and on which a rim portion around the center aperture of the disc is set, a thrusting and supporting unit for thrusting and supporting the recording disc with respect to the table section, and centering unit provided at a proximal side of the fitting member and adapted for thrusting the rim portion around the center aperture of the recording disc with the center rotation of the fitting member.

Abstract: The present invention is to provide an apparatus for recording and/or reproducing a recording medium which comprises recording and reproducing means for recording or reproducing data on or from a recording medium in which management information for recording or reproducing data is recorded together with data, designating means for designating a pause position of one data and control means for controlling the recording and reproducing means based on the management information such that the recording and reproducing means records or reproduces data on or from the recording medium, recognizing a time point at which the designating means is operated during data is recorded on or reproduced from the recording medium by the recording and reproducing means and controlling the recording and reproducing means so that the recording and reproducing means rewrites the management information.