Abstract: A diffusion plate includes a plurality of superimposed basic patterns, each having a large number of microstructures. The microstructures are located in two dimensional periodic arrangements, and lattice vectors, corresponding to the periodic arrangement of the microstructures, vary in accordance with the pattern. The invention also discloses a method for manufacturing a master die for such a diffusion plate, and a focusing screen using the diffusion plate.

Abstract: A diffusion plate includes a plurality of superimposed basic patterns, each having a large number of microstructures, wherein the microstructures are located in two dimensional periodic arrangements, and wherein lattice vectors, corresponding to the periodic arrangement of the microstructures, vary in accordance with the pattern. The invention also discloses a method for manufacturing a master die for such a diffusion plate, and a focusing screen using the diffusion plate.

Abstract: A diffusion plate includes a plurality of superimposed basic patterns, each having a large number of microstructures. The microstructures are located in two dimensional periodic arrangements, and lattice vectors, corresponding to the periodic arrangement of the microstructures, vary in accordance with the pattern. The invention also discloses a method for manufacturing a master die for such a diffusion plate, and a focusing screen using the diffusion plate.

Abstract: A collimating lens system comprises a chromatic aberration correction element and a converging lens which has both surfaces formed of a convex aspherical surface. The converging lens has no aberrations except chromatic aberration. The chromatic aberration correction element has small refractive power adapted to correct a chromatic aberration of the converging lens, and the element is constructed of positive and negative lenses cemented to each other. The positive lens and the negative lens have almost the same refractive index, and have different dispersion.

Abstract: The optical disk apparatus of this invention is provided with a memory for memorizing a track offset signal corresponding to an angle of a galvanic mirror, or a photodetector having two pairs of photodetecting regions to detect different tracking error signals to each other, or two galvanic mirrors which are adjusted so as to prevent the track offset signal.

Abstract: A compound prism including a plurality of unit prisms which have reflective interfaces defined by outer and/or inner surfaces thereof and which are arranged so that light is reflected by an inner surface of the interface of one of the unit prisms and by an outer surface of the interface of another unit prism.

Abstract: An interferometer causes a reference beam and a subject beam reflected from a roof surface to interfere with each other to form an interference fringe, which is detected by an image detecting element in its measuring area. Detection data from the image detecting element is processed by an image processing circuit, and then subjected to phase difference detection. A continuous function is determined as an approximation to a relationship between phase data and unit measuring areas located in a direction perpendicular to a line corresponding to a ridge line of the roof surface. A analysis relating to a roof angle is performed based on the continuous function thus determined.

Abstract: A device in which an offset is added to a focusing error signal to control an objective lens and thereby reduce the generation of cross-talk when a beam spot that is converged on an optical disk crosses over a wall of a groove of a track of the disk. By adding the offset to the focusing error signal, the objective lens is moved out of focus with the disk. Thus, the shape of a beam spot formed on a photo sensor is changed from a circle to an ellipse. A condenser lens provided for forming the beam spot is moved along the optical axis thereof in such a manner that an output of a recorded signal of the disk is at a maximum value. As a result, the objective lens is brought into focus on the disk. Thereafter, the objective lens is focused on the disk in accordance with the focusing error signal to which the offset is added, while maintaining the beam spot in the shape of an ellipse.

Abstract: An optical axis adjusting apparatus is provided and includes a laser beam source, a beam shaping prism for shaping a laser beam of elliptical flux emitted from the laser beam source into a laser beam of circular flux, and an angle adjusting device which adjusts the angular direction of the outgoing laser beam emitted from the shaping prism.

Abstract: An optical axis adjusting apparatus is provided and includes a laser beam source, a beam shaping prism for shaping a laser beam of elliptical flux emitted from the laser beam source into a laser beam of circular flux, a parallel shift mechanism which shifts the light rays of the laser beam in a parallel fashion, and a rotation adjusting mechanism for rotatably adjusting a parallel plate.

Abstract: In the magneto-optic recording/reproduction apparatus, a light beam from a semiconductor laser that can be used with two wavelengths, for recording and reproduction is converged by an objective lens on a magneto-optic disk, a predetermined offset is added to this focusing error signal by an offset adjusting circuit, and the objective lens is driven in the direction of the optical axis based on the focusing error signal to which an offset was added.

Abstract: An optical system of an optical disk apparatus having plural optical elements characterized in that the optical element having aberration which can counterbalance the wave front aberration of the whole optical system is disposed, or a direction of aberration of each existing optical element is adjusted in order to correct the wave front aberration.

Abstract: An optical axis adjusting apparatus is provided and includes a laser beam source, a beam shaping prism for shaping a laser beam of elliptical flux emitted from the laser beam source into a laser beam of circular flux, and an angle adjusting device which adjusts the angular direction of the outgoing laser beam emitted from the shaping prism.

Abstract: A compound prism including a plurality of unit prisms which have reflective interfaces defined by outer and/or inner surfaces thereof and which are arranged so that light is reflected by an inner surface of the interface of one of the unit prisms and by an outer surface of the interface of another unit prism.

Abstract: In a method of measuring/adjusting a relative displacement of objects using diffraction gratings, two monochromatic beams each having slightly different frequencies are synthesized to cause optical heterodyne interference so as to generate two beat signals. One of the beat signals is used as a reference signal. The other is used as a first interference beat signal generated by emitting the two monochromatic beams on a first diffraction grating arranged on a first object and by synthesizing two diffracted beams generated from the first diffraction grating by the above emission to cause optical heterodyne interference. A phase difference between the reference beat signal and the interference beat signal is then detected. Finally, the relative displacement is measured/adjusted in accordance with the phase difference.

Abstract: A method of adjusting a relative positional relationship between two objects uses a diffraction grating. A first diffraction grating is arranged on a first object located to oppose a second object, a reflecting surface is arranged at a position of the second object which corresponds to the first diffraction grating, and the method includes the step of irradiating the first diffraction grating with a radiation beam of coherent light or quasi-monochromatic light and measuring/setting the gap between the first and second objects in accordance with a change in intensity of one of the diffracted light components from the first diffraction grating.