Abstract: In a projection display apparatus, light from a light source is separated into a plurality of beams having different wavelength regions, a plurality of image display elements (123r, 123g, 123b) are inserted in the optical paths of the respective separated beams so as to be illuminated by the beams. A color combiner (XDP) is provided for combining the beams emerging from the plurality of image display elements. The beams combined by the color combiner are projected on a projection surface. A diffraction optical element (124) is inserted in at least one of a plurality of optical paths between the plurality of image display elements and the color combiner.

Abstract: A scanning type image display optical system of the present invention comprises: a reflecting surface; an optical scanning unit which forms a two-dimensional image on the reflecting surface by light scanning; and an ocular optical system which leads light from the two-dimensional image formed on the reflecting surface to an observer.

Abstract: A diffracting optical element has a structure that a plurality of layers having a periodic relief pattern varying in height in a period are laminated in proximity to or close contact with each other. The diffracting optical element includes two layers equal in the height of the relief pattern and opposite to each other in the direction in which the height of the relief pattern varies in a period, and another layer differing in the height of the relief pattern from the two layers. Materials forming the three layers differ in dispersion from one another.

Abstract: An image display apparatus includes scanning unit for scanning a beam by driving a reflecting surface for reflecting a beam from the light source part, an optical element having an incident surface which the reflected beam from the scanning unit enters, at least one inner reflecting surface which has a curved surface and reflects the beam coming from the incident surface, and an exit surface from which the beam reflected by the inner reflecting surface emerges, and a reflecting element for reflecting the beam emerging from the optical element and guiding the beam to an observer's eye.

Abstract: An image sensing apparatus having a solid-state image sensing device is provided with an optical modulation element, made of electrochromic element for R, G, and B layers, whose spectral transmission characteristics can be independently controlled. By controlling the spectral transmission characteristics of each layer of the optical modulation element, visible light in R, G and B wavelength ranges is controlled so as to incident on a photoelectric converter of the solid-state image sensing device at different times.

Abstract: An optical low-pass filter comprises a phase advancing area which advances a phase of a wavefront of an incident pencil of rays with respect to a phase of a wavefront of a center of the incident pencil of rays, and a phase retarding area which retards the phase of the wavefront of the incident pencil of rays with respect to the phase of the wavefront of the center of the incident pencil of rays, the phase advancing area and the phase retarding area alternately existing in the optical low-pass filter, and an optical apparatus comprises an image forming optical system, an image pickup element, and such an optical low-pass filter.

Abstract: This invention can provide an optical system which has a diffractive optical element that can suppress generation of flare or the like due to light rays of unnecessary orders of diffraction caused by the wavelength dependence of the diffractive optical element without using any complicated arrangement. In an optical system, light from a light source is separated into light rays of predetermined wavelength regions by a color separation optical system. Those light rays are incident on pixels of an image display element having a plurality of pixels in correspondence with the predetermined wavelength regions. An image displayed on the image display element is projected in an enlarged scale by a projection optical system. A diffractive optical element is disposed near the pupil of the projection optical system, and the diffraction efficiency of the diffractive optical element can be optimized in each of predetermined wavelength regions.

Abstract: In a projection display apparatus, light from a light source is separated into a plurality of beams having different wavelength regions, a plurality of image display elements (123r, 123g, 123b) are inserted in the optical paths of the respective separated beams so as to be illuminated by the beams. A color combiner (XDP) is provided for combining the beams emerging from the plurality of image display elements. The beams combined by the color combiner are projected on a projection surface. A diffraction optical element (124) is inserted in at least one of a plurality of optical paths between the plurality of image display elements and the color combiner.

Abstract: The present invention provides an optical scanning apparatus which has a light modulating element capable of changing the propagating state of light, an illuminating optical system for illuminating the light modulating element with light, and a scanning optical system for scanning the light from the light modulating element, the scanning optical system having a light deflector for selectively deflecting a beam of the light from the light modulating element which propagates in a predetermined direction, and which is made more compact than in the prior art.

Abstract: The invention provides a method and apparatus for caching data in a highly efficient fashion during a data reproducing process thereby reducing the access time. In the case where it is determined that the type of a data request is not a sequential data request, the cache memory is divided into a plurality of memory segments and data is stored in a particular memory segment so that the existing data buffered in the cache memory is further kept in the respective segments without being entirely purged even in a mode other than the sequential reading mode. This makes it possible that the data kept in the cache memory (without being purged) is used, for example, in a two-point reading operation performed in response to the following data transfer request. Yet, even in the random reading mode, the data buffered in the past is kept in the divided segments of the cache memory as long as possible so as to maximize the probability that requested data can be found in the cache memory in the future operations.

Abstract: A stereoscopic image photographing optical system includes a pair of front optical components of negative refractive power, a combining optical element for superposing respective optical axes of the pair of front optical components on each other, a rear optical component disposed such that the superposed optical axes coincide with an optical axis of the rear optical component, a pair of shutters capable of independently controlling amounts of transmission of light fluxes respectively entering the pair of front optical components from an object, and a pair of deflection mirrors arranged to deflect light fluxes coming from the pair of front optical components and to guide the deflected light fluxes to the combining optical element, wherein the optical system forms parallactic images in a time-series manner by causing the pair of shutters to alternately change the amounts of transmission of light fluxes respectively entering the pair of front optical components from the object.

Abstract: An optical low-pass filter comprises a phase advancing area which advances a phase of a wavefront of an incident pencil of rays with respect to a phase of a wavefront of a center of the incident pencil of rays, and a phase retarding area which retards the phase of the wavefront of the incident pencil of rays with respect to the phase of the wavefront of the center of the incident pencil of rays, the phase advancing area and the phase retarding area alternately existing in the optical low-pass filter, and an optical apparatus comprises an image forming optical system, an image pickup element, and such an optical low-pass filter.

Abstract: An optical element comprises a lens made of a material for shutting off all or most of light in the infrared region, and an optical low-pass filter, wherein the lens and the optical low-pass filter are incorporated with each other.

Abstract: An external circulation type ball thread device includes a threaded shaft having a ball thread groove in the outer surface; a ball nut having a ball thread groove in the inner surface; and a number of balls fitted between those ball thread grooves, the balls being circulated while being led in a ball circulating tube which is secured to the outer surface of the ball nut with a tube retaining member. In the device, the ball nut has in the outer surface a tube supporting groove which is formed along the ball circulating tube which is arranged inclined with respect to the axis of the threaded shaft, to support the bottom of the ball circulating tube, and an annular groove which is formed across the tube supporting groove; and the tube retaining member is made of an elastic thin plate in such a manner that the tube retaining member is substantially C-shaped in section so as to be fitted in the annular groove, and has an engaging groove which is engaged with the ball circulating tube.

Abstract: A vertical wafer supporting boat is provided in which adequate reaction gas is supplied to the portion of a wafer surface to be treated which is inserted in holding grooves in members of the wafer supporting boat during the heat treatment and thus uniform heat treatment is achieved across the surface of each wafer. The particular groove shape preferably exploits the rotation of the boat in a vertical furnace to thereby uniformly supply the reaction gas on the entire surface to be treated of each of the wafers disposed in the boat. The holding grooves are inclined relative to a direction tangent to a wafer edge in order that the clearance facing the surface to be treated of a wafer is profiled to have an edge-like space by gradually increasing the width in the tangential direction of the wafer and, preferably, the internal groove surface opposed to the surface to be treated of the wafer is inclined to increase in width toward the center of the wafer.

Abstract: A control device for a brushless motor capable of stopping the brushless motor without any complicated control. The control device includes a rotation control section to which an output of a position detector detecting a polarity of a magnet field of a rotor on a side of a stator is fed and which generates a driving signal of a predetermined polarity based on the output of the position detector input thereto. Also it includes a motor driving section to which the driving signal is fed and which flows an excitation current through a driving coil for a phase determined depending on a polarity of the driving signal input thereto.