Abstract: An image display apparatus has: a display element for displaying an image; a light source section for supplying an illumination light to the display element; a reflection type hologram for diffracting and reflecting the illumination light so as to guide the illumination light to the display element; and an eyepiece optical system for guiding an image light from the display element to an eye of a viewer so as to provide an enlarged virtual image of the image. The reflection type hologram has diffusing properties. Since the reflection type hologram diffuses the illumination light, an incident angle of the illumination light with respect to the display element is widened to a certain extent. Since the display element does not change a propagating direction of a light ray, a propagating direction of the image light is widened similarly to widening of the incident angle, thereby enlarging the observation pupil.

Abstract: At least one of right and left image display apparatuses is provided with an optical axis adjustment mechanism. The optical axis adjustment mechanism changes relative positional relationship between an image displayed on a display device and an ocular optical system in a direction intersecting an optical axis to thereby adjust an angle formed by a pair of right and left optical axes. In this condition, a light source is so arranged as to be substantially conjugate with an optical pupil. The optical axis adjustment mechanism changes the positional relationship described above without changing a position of the optical pupil relative to the ocular optical system. This permits, even when the apparatus is originally designed such that light intensity is high at a designed optical pupil position, achieving the light intensity at this optical pupil position even after optical axis adjustment.

Abstract: An image display apparatus, which is mounted on a head or face of a wearer attachably and detachably and allows the wearer to view an image and hear sound, includes a long formed temple supported by a temporal region of head or an ear when the wearer is wearing the image display apparatus; a speaker that generates sound, a sound generating face thereof being insertable into the ear at a vicinity of an opening of the ear; and a position adjusting mechanism that holds the speaker, attachably to and detachably from the temple, and movably at least substantially along a surface of the temporal region of the head.

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: An image display apparatus has: a display element for displaying an image; a light source section for supplying an illumination light to the display element; a reflection type hologram for diffracting and reflecting the illumination light so as to guide the illumination light to the display element; and an eyepiece optical system for guiding an image light from the display element to an eye of a viewer so as to provide an enlarged virtual image of the image. The reflection type hologram has diffusing properties. Since the reflection type hologram diffuses the illumination light, an incident angle of the illumination light with respect to the display element is widened to a certain extent. Since the display element does not change a propagating direction of a light ray, a propagating direction of the image light is widened similarly to widening of the incident angle, thereby enlarging the observation pupil.

Abstract: An image display apparatus has: a display element for displaying an image; a light source section for supplying an illumination light to the display element; a reflection type hologram for diffracting and reflecting the illumination light so as to guide the illumination light to the display element; and an eyepiece optical system for guiding an image light from the display element to an eye of a viewer so as to provide an enlarged virtual image of the image. The reflection type hologram has diffusing properties. Since the reflection type hologram diffuses the illumination light, an incident angle of the illumination light with respect to the display element is widened to a certain extent. Since the display element does not change a propagating direction of a light ray, a propagating direction of the image light is widened similarly to widening of the incident angle, thereby enlarging the observation pupil.

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: A display apparatus which has a mirror with a free curved reflective surface of which curvature fluctuates with inflection points, a liquid crystal display (LCD), a back light and a polarizer. Light of an image which was modulated by the LCD is reflected by the free curved reflective surface and passes through the polarizer. Then, the light is directed to an optical pupil. Since the curvature of the free curved reflective surface fluctuates with inflection points, curvature of field and distortion can be corrected properly, and an image of high quality can be formed.

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 display apparatus which has a mirror with a free curved reflective surface of which curvature fluctuates with inflection points, a liquid crystal display (LCD), a back light and a polarizer. Light of an image which was modulated by the LCD is reflected by the free curved reflective surface and passes through the polarizer. Then, the light is directed to an optical pupil. Since the curvature of the free curved reflective surface fluctuates with inflection points, curvature of field and distortion can be corrected properly, and an image of high quality can be formed.

Abstract: A band-pass filter has a reflecting optical element having a fixed reflection angle selection region for wavelengths of a given region, and has an optical path such that reflection is performed at least once and transmission is performed at least once at the reflecting optical element.

Abstract: When an optical device is produced by bonding on a transparent base member an optical element formed as a hologram, the optical element and the transparent base member are both formed of an acrylic material. In particular when, as an optical device, an eyepiece optical system is produced by holding an optical element between two transparent base members, the optical element, the transparent base members, and the adhesive with which the transparent base members are joined together are all formed of an acrylic material. In this way, by building an eyepiece optical system with a similar kind of material, namely an acrylic material, it is possible to obtain increased adhesion among the materials of the individual components of the eyepiece optical system without performing special processing. Moreover, the transparent base members formed of an acrylic material more securely absorb shock and external pressure than those formed of glass.

Abstract: The exposure amounts of R, G, and B laser light emitted from a fabrication light source are so adjusted that the diffraction efficiency at R, G, and B wavelengths in an optical element is commensurate with the light intensity at the R, G, and B wavelengths in the light emitted from a reproduction light source. For example, when the light intensity of the light emitted from the reproduction light source is increasingly low at the B, G, and R wavelengths in this order, the exposure amounts of the R, G, B, laser light emitted from the fabrication light source are so adjusted that the diffraction efficiency in the optical element is increasingly high at the B, G, and R wavelengths in this order. In this way, the hue of the light (reproduction light) obtained from the reproduction light source via the optical element can be adjusted to the hue desired with every reproduction light source used, while the most use is made of the light emitted from the reproduction light source actually used.

Abstract: A band-pass filter has a reflecting optical element having a fixed reflection angle selection region for wavelengths of a given region, and has an optical path such that reflection is performed at least once and transmission is performed at least once at the reflecting optical element.

Abstract: An image display apparatus using liquid crystal is provided that offers high contrast and that excels in versatility. The image display apparatus has a liquid crystal layer for displaying an image that is held between a pair of transparent substrates, an illumination portion that feeds the liquid crystal layer with illumination light, a polarizing plate that serves as a polarizer that turns the light from the illumination portion into a linearly polarized light, a polarizing plate that serves as an analyzer that transmits only the linearly polarized light that emerges from the liquid crystal layer when no voltage is applied, and a birefringent film. The birefringent film produces in the light transmitted therethrough a phase difference that varies in the direction of the thickness thereof, and produces the phase difference in such a direction as to cancel the phase difference produced by the liquid crystal layer in the light emerging therefrom when a voltage is applied.

Abstract: An image observation device which is so arranged that a user can look an image in through an ocular window thereof with the device being fitted to the user's head for example, that the image changes in linkage with movement of the user's head, and that unnecessary change of the image is prevented during the observation. The image observation device includes an eye access detector for detecting whether the user's eyes approach thereto or not, and includes, a controller by the operation of which the image changes in linkage with movement of the user's head only if the eye access detector detects that the user's eyes approach thereto, and by the operation of which the image does not change in linkage with movement of the user's head if the eye access detector does not detect that the user's eyes approach thereto.

Abstract: A band-pass filter has a reflecting optical element having a fixed reflection angle selection region for wavelengths of a given region, and has an optical path such that reflection is performed at least once and transmission is performed at least once at the reflecting optical element.

Abstract: A head-mounted image display apparatus is provided with: an image display element; a projection optical system that projects an image displayed by the image display element, so as to be enlarged; a reflective screen onto which the image is projected by the projection optical system; and a combiner disposed between the projection optical system and the screen. The combiner transmits the image light from the projection optical system and directs it to the screen, and reflects the image light reflected at the screen and directs it to the user's pupil.

Abstract: An image display apparatus has an image display device for displaying an image, an eyepiece optical system, including a holographic magnifying optical element, for magnifying and projecting the image, and a holographic filter, disposed either as part of the image display device or in the optical path between the image display device and the eyepiece optical system, for restricting the wavelength range of the image light.

Abstract: An information display device provided with a prism having at least two reflecting surfaces arranged in facing each other and a hologram surface formed of a reflection-type hologram. And at least one of the two reflecting surfaces is a light-beam-selective surface that selectively transmits or reflects light in accordance with its incident angle. An image light emitted from an image display means enters the prism, and is reflected between the reflecting surfaces, and then is diffractively reflected on the hologram surface, and, after being transmitted through the light-beam-selective surface, is directed to an observer's pupil.