Abstract: A volume phase type hologram has a diffraction lattice recorded in a poly(N-vinyl carbazole) polymer layer where the diffraction lattice is recorded throughout the thickness direction of the polymer layer. A method for preparing the volume phase type hologram has the steps of exposing a photosensitive polymer layer provided on a substrate to an interference pattern; subjecting the polymer layer having been exposed to a first development treatment with a first organic solvent; and peeling the polymer layer off the substrate and subjecting the polymer to a second development treatment with a second organic solvent preferentially from the face that had been in contact with the substrate.

Abstract: An optical logic operation apparatus includes an optical induction refractive index crystal having first and second planes parallel to each other and a device for inputting a coherent probe light from the first plane of the crystal. At least one of the first light output from the first plane of the crystal and the second light output from the second plane of the crystal is taken out so that one of the first and second lights is amplified by the two-wave coupling of the probe light reflected by the second plane and the probe light inputted from the first plane and the other light is attenuated likewise by the two-wave coupling. The inputted image is projected onto the crystal by use of light incoherent to the probe light. With the incidence of the incoherent light, a gain distribution corresponding to the inputted image is generated in the crystal so as to modulate the first and second lights spatially.

Abstract: A head-up display device comprises an image generator, a beam combiner having a light receiving plane tilted laterally for receiving a light from the image generator and diffracting the light, and a compensator arranged between the image generator and the beam combiner for receiving the light from the image generator by a light receiving plane thereof and directing the light to the beam combiner to correct an aberration created by the beam combiner. The compensator is arranged such that a normal line extending through a center of the light receiving plane thereof and a normal line extending through a center of the light receiving plane of the beam combiner are in a common plane.

Abstract: A method of observing information includes the steps of converting a radiation beam into a visible harmonic beam conforming to the information and observing the information by the harmonic beam. An apparatus for observing information therethrough includes a source for producing a radiation beam conforming to the information, and a converter for converting the radiation beam into a visible harmonic beam, with the information being observed with the aid of the harmonic beam. In addition, a head-up display apparatus includes a source for producing a radiation beam conforming to information to be displayed, a converter for converting the radiation beam into a visible harmonic beam, and a beam combiner for receiving the harmonic beam and directing it in a predetermined direction to effect the display of the information by the harmonic beam.

Abstract: A display apparatus comprises a display, a first diffraction grating for diffracting light from the display, and a second diffraction grating for diffracting diffracted light from the first diffraction grating, so that a half-width of the first diffraction grating is set to be larger than that of the second diffraction grating.

Abstract: An optical head device comprises a light source, a light splitter for reflecting a light emitted from the light source by a first plane thereof to direct the light to an information carrier and transmitting the light from the information carrier through the first plane, a photo-detector for detecting the light from the information carrier, and a diffraction grating structure arranged on a second plane of the light splitter for diffracting the light transmitted through the first plane and directing it to the photo-detector.

Abstract: a display apparatus comprises, a display unit, a first diffraction grating for diffracting the light from the display unit, and a second diffraction grating for diffracting the diffracted light from the first diffraction grating, the apparatus being constructed in such a manner that the optical path length between the display unit and the first diffraction grating is shorter than that between the first and second diffraction gratings.

Abstract: A photosensitive material is provided which comprises (i) a substrate comprising a crosslinked polymer having a transmittance of 90% or more in a wavelength region of from 400 to 700 nm and a refractive index of 1.55 or more, and (ii) a sensitive material layer provided on the substrate and mainly composed of a vinylcarbazole polymer. A hologram member employing the photosensitive material is also provided.

Abstract: A hologram member and a method of preparing a volume type phase hologram film includes forming a volume type phase hologram in a polymer film formed on a substrate and comprised of a vinylcarbazole polymer, separating the polymer film from the substrate and allowing the hologram to be supported on the substrate so that the surface of the hologram not having contacted the substrate, contacts the substrate.

Abstract: A hologram member is provided which comprises a substrate, and a film in which a volume type phase hologram is recorded. The film is provided peelably on the substrate. The substrate preferably has a light transmittance of 30% or more at a wavelength of from 450 to 800 nm. The film may comprise a vinylcarbazole.

Abstract: A method of preparing a volume type phase hologram film comprises forming a volume type phase hologram in a polymer film formed on a substrate and comprises of a polymer of vinylcarbazoles, and separating the polymer film from the substrate. Preferably, the polymer film is separated from the substrate in a liquid inert to the hologram.

Abstract: An optical head device comprises a light source, condensing optics for condensing a light beam emitted from the light source on an optical recording medium, a photodetector for detecting the light of the light beam reflected from the recording medium, and a beam splitter having a diffraction grating arranged in the optical path of the light beam entering the recording medium from the light source along a plane substantially perpendicular to the optical axis of the incident light beam to cause the light reflected light from the recording medium to be diffracted by the diffraction grating and directed to the photodetector.