Abstract: An optical head device having a broadband phase plate of transforming at least three linearly polarized light beams having different wavelengths into circularly polarized light beams, is obtained. A broadband phase plate comprising two phase plates 9A and 9B laminated with e.g. an adhesive agent so that their optical axes are crossed, wherein provided that wavelengths of linearly polarized incident light beams are ?1, ?2 and ?3 (?1<?2<?3), at least one or both of the two phase plates has such a phase difference characteristics that a ratio R(?1)/R(?3) and a ratio R(?2)/R(?3) between retardation values of the wavelengths are smaller than 1 and R(?1)/R(?3) is smaller than R(?2)/R(?3), is integrated in the optical head device.

Abstract: A polarizing diffraction element having a wavelength selectivity which functions as a polarizing diffraction element at a wavelength ?1, and which does not function as a diffraction grating not depending on incident polarization state and shows high transmittance at a wavelength ?2, and an optical head device employing the element, are provided. The polarizing diffraction element selectively diffracts or transmits incident light having two different wavelengths each containing a first circularly polarized light and a second circularly polarized light having a rotation opposite from the rotation of the first circularly polarized light, depending on wavelength and polarization state of the incident light. Then, a reflective wavelength region for at least the first circularly incident light, does not contain said two incident wavelengths.

Abstract: To provide optical elements such as a phase plate suitably used in a broadband range and a polarizing diffraction element excellent in diffraction efficiency, a polymerizable liquid crystal composition to be used for them, and an optical head device using them.

Abstract: To provide optical elements such as a phase plate suitably used in a broadband range and a polarizing diffraction element excellent in diffraction efficiency, a polymerizable liquid crystal composition to be used for them, and an optical head device using them.

Abstract: An optical head device having a broadband phase plate of transforming at least three linearly polarized light beams having different wavelengths into circularly polarized light beams, is obtained. A broadband phase plate comprising two phase plates 9A and 9B laminated with e.g. an adhesive agent so that their optical axes are crossed, wherein provided that wavelengths of linearly polarized incident light beams are ?1, ?2 and ?3 (?1<?2<?3), at least one or both of the two phase plates has such a phase difference characteristics that a ratio R(?1)/R(?3) and a ratio R(?2)/R(?3) between retardation values of the wavelengths are smaller than 1 and R(?1)/R(?3) is smaller than R(?2)/R(?3), is integrated in the optical head device.

Abstract: A polarizing diffraction element having a wavelength selectivity which functions as a polarizing diffraction element at a wavelength ?1, and which does not function as a diffraction grating not depending on incident polarization state and shows high transmittance at a wavelength ?2, and an optical head device employing the element, are provided. The polarizing diffraction element selectively diffracts or transmits incident light having two different wavelengths each containing a first circularly polarized light and a second circularly polarized light having a rotation opposite from the rotation of the first circularly polarized light, depending on wavelength and polarization state of the incident light. Then, a reflective wavelength region for at least the first circularly incident light, does not contain said two incident wavelengths.

Abstract: The present invention provides a photopolymerizable liquid crystal monomer having high durability, a low melting point and an enantiotropic property. The photopolymerizable liquid crystal monomer is a 4-(4-(alkyloxycarbonyloxy)benzoyloxy)phenyl acrylate represented by the following formula A [wherein Ph is a 1,4-phenylene group, and R is an alkyl group]: CH2═CHCOO—Ph—OCO—Ph—OCOO—R  Formula A Further, the present invention provides a polymer liquid crystal obtained by polymerizing a composition containing the monomer. Further, the present invention provides an optical element employing the polymer liquid crystal, and an optical head employing the optical element as a polarizing hologram element.

Abstract: An optically anisotropic diffraction grating for an optical read/write head, comprising optically isotropic polymer liquid crystal held between two transparent base plates. Gratings of different refractive indexes are formed by periodically changing the orientation of the polymer liquid crystal of the diffraction grating. This enables a high light-utilization efficiency and a high reliability to be obtained.

Abstract: As an optically anisotropic diffraction grating in an optical head for reading and/or writing of an optically recording medium, optically anisotropic diffraction grating which comprises an optically anisotropic polymer liquid crystal sandwiched between two transparent substrates are used. The optically anisotropic polymer liquid crystal can have an alignment direction periodically changed to form a grating of different refractive indices, obtaining a high-utilization efficiency by light ray and a high degree of reliability.

Abstract: An object is to provide an optical head device whereby the light utilization efficiency can be increased and which can be produced at a low cost. A glass substrate 1 having projections and recesses 2 formed by patterning a SiON type transparent thin film on its inner surface by dry etching, and a second glass substrate 3 having a polyimide film 4 formed as an alignment film on its inner surface, are laminated with a space, the periphery is sealed by a sealing material made of an epoxy resin 5, and liquid crystal 6 is injected under vacuum into the interior to form an optically anisotropic diffraction grating. On the outer surface of this second glass substrate 3, a quarter-wave film 7 is laminated, and a third glass substrate 9 is bonded by a photopolymer 8 to obtain a diffracting element 10. This diffracting element 10 is disposed between a light source and an optical recording medium to obtain an optical head device.

Abstract: High molecular liquid crystal obtained by photopolymerizing a liquid crystal composition which comprises CH2═CHCOO—X—OC6H4—C6H4CN (X is an alkylene group) and CH2═CHCOOC6H4—C6H4CN. An optical element which is a polarized hologram element made by using the high molecular liquid crystal and an optical head having the polarized hologram element as a beam splitter.

Abstract: A liquid crystal display element comprises a pair of substrates provided with electrodes and a liquid crystal and solidified matrix composite material, disposed between the pair of substrates, which includes a nematic liquid crystal dispersed and held in a solidified matrix, the nematic liquid crystal being such that the refractive index of the liquid crystal is changed depending on states of applying a voltage wherein in a state, the refractive index of the liquid crystal substantially coincides with that of the solidified matrix to thereby pass light, and in the other state, the former does not coincide with the latter to thereby cause the scattering of light, wherein the refractive index anisotropy .DELTA.n of the liquid crystal used is 0.18 or higher, and the dielectric anisotropy .DELTA..epsilon..sub.LC of the liquid crystal used satisfies the relation of 5<.DELTA..epsilon..sub.LC <13.

Abstract: An object is to provide an optical head device whereby the light utilization efficiency can be increased and which can be produced at a low cost. A glass substrate 1 having projections and recesses 2 formed by patterning a SiON type transparent thin film on its inner surface by dry etching, and a second glass substrate 3 having a polyimide film 4 formed as an alignment film on its inner surface, are laminated with a space, the periphery is sealed by a sealing material made of an epoxy resin 5, and liquid crystal 6 is injected under vacuum into the interior to form an optically anisotropic diffraction grating. On the outer surface of this second glass substrate 3, a quarter-wave film 7 is laminated, and a third glass substrate 9 is bonded by a photopolymer 8 to obtain a diffracting element 10. This diffracting element 10 is disposed between a light source and an optical recording medium to obtain an optical head device.

Abstract: A composition for use in a liquid crystal optical element, such as a liquid crystal display or laser shutter device, comprised of a liquid crystal material and a solidified polymer material. The liquid crystal is such that its refractive index is changed depending on states of applying a voltage. In one state, the refractive index of the liquid crystal substantially coincides with the refractive index of the solidified matrix to thereby pass light. While in the other state, the refractive index of the liquid crystal does not coincide with the refractive index of the solidified matrix to thereby cause the scattering of light. Specifically, the liquid crystal material used in the composition has a refractive index anisotropy (.DELTA.n) is greater than 0.18 and the dielectric anisotropy (.DELTA..epsilon.) satisfies the relation of 5<.DELTA..epsilon.<11.6.

Abstract: An illumination device for a direct viewing type display element comprising a flat light guide; a light source set such that light is incident on a side portion of said flat light guide; a polarized light separating flat set on a first side of a light emitting side of the flat light guide for transmitting a p polarized light component and reflecting at least a portion of an s polarized light component with respect to a light ray substantially having a predetermined direction of incidence; and a light reflecting sheet disposed on a second side opposite to said light emitting side of the flat light guide in parallel with the light emitting site.

Abstract: An active matrix liquid crystal display element and a projection type active matrix liquid crystal display device by which a display can be obtained which is good in color balance and high in brightness and also in contrast ratio. The display element includes a liquid crystal material held between an active matrix substrate and a counter electrode substrate. The liquid crystal material is formed from a liquid crystal polymer composite wherein nematic liquid crystal is contained dispersively in a polymer matrix having a refractive index which coincides with the ordinary refractive index of the liquid crystal used, and a silicon thin film transistor is used as an active element on the active matrix substrate. The display device includes such an active matrix liquid crystal display element, a light source for projection light, and an optical system of projection.

Abstract: A liquid crystal display element comprises a pair of substrates provided with electrodes and a liquid crystal and solidified matrix composite material, disposed between the pair of substrates, which includes a nematic liquid crystal dispersed and held in a solidified matrix, the nematic liquid crystal being such that the refractive index of the liquid crystal is changed depending on states of applying a voltage wherein in a state, the refractive index of the liquid crystal substantially coincides with that of the solidified matrix to thereby pass light, and in the other state, the former does not coincide with the latter to thereby cause the scattering of light, wherein the refractive index anisotropy .DELTA.n of the liquid crystal used is 0.18 or higher, and the dielectric anisotropy .DELTA..epsilon..sub.LC of the liquid crystal used satisfies the relation of 5<.DELTA..epsilon..sub.LC <13.

Abstract: A projection type display apparatus comprises a light source optical system having an anisotropic luminance distribution, a transparent-scattering type display element for controlling light emitted from the light source optical system and a projection optical system having an aperture which projects the transmitted light, wherein the aperture of the projection optical system is an aperture having a non-circular opening which is disposed in the vicinity of the focal point of the transmitted light of the transparent-scattering type display element.

Abstract: An illumination device for a direct viewing type display element comprising a flat light guide; a light source set such that light is incident on a side portion of said flat light guide; a polarized light separating flat set on a first side of a light emitting side of the flat light guide for transmitting a p polarized light component and reflecting at least a portion of an s polarized light component with respect to a light ray substantially having a predetermined direction of incidence; and a light reflecting sheet disposed on a second side opposite to said light emitting side of the flat light guide in parallel with the light emitting site.

Abstract: An illumination device for a direct viewing type display element comprising a flat light guide; a light source set such that light is incident on a side portion of said flat light guide; a polarized light separating flat set on a first side of a light emitting side of the flat light guide for transmitting a p polarized light component and reflecting at least a portion of an a polarized light component with respect to a light ray substantially having a predetermined direction of incidence; and a light reflecting sheet disposed on a second side opposite to said light emitting side of the flat light guide in parallel with the light emitting site.