Abstract: An illuminating light modulating device modulates at least one of wavelength, phase, intensity, polarization, and coherency of the light emitted to an object by an illuminating device. A pupil modulating device is disposed near a pupil plane of an objective lens, and modulates at least one of phase, intensity and direction of polarization of the luminous flux including the information of the object. An image pickup device is disposed on a plane on which the image of the object is formed by the objective lens and an imaging lens, and picks up the image of the object. An image analysis device analyzes the image of the object picked up by the image pickup device. A parameter decision device adjusts the modulation amounts of the illuminating light modulating device and the pupil modulating device by using the image information of the object analyzed by the image analysis device.

Abstract: An illuminating light modulating device modulates at least one of wavelength, phase, intensity, polarization, and coherency of the light emitted to an object by an illuminating device. A pupil modulating device is disposed near a pupil plane of an objective lens, and modulates at least one of phase, intensity and direction of polarization of the luminous flux including the information of the object. An image pickup device is disposed on a plane on which the image of the object is formed by the objective lens and an imaging lens, and picks up the image of the object. An image analysis device analyzes the image of the object picked up by the image pickup device. A parameter decision device adjusts the modulation amounts of the illuminating light modulating device and the pupil modulating device by using the image information of the object analyzed by the image analysis device.

Abstract: The invention is directed to a focusing optical system for semiconductor lasers, which is regulated in terms of magnification power in both its directions normal to the optical axis, so that the back focus of sufficient magnitude can be made equal in both the directions and the magnitude of aberration can be regulated to achieve an improvement in focusing efficiency, and in which a light beam from a semiconductor laser having varying exit angles in the horizontal and vertical directions is focused on a spot having substantially equal diameters in the horizontal and vertical directions. This focusing optical system comprises first lens unit L1 including a rotation asymmetric lens having positive power in the direction defined by a large exit angle at which a laser beam emanates from the laser, a second lens unit L2 including at least one lens of negative power, and a third lens unit L3 that is a rotation asymmetric lens unit having positive power in the directions defined by both large and small exit angles.

Abstract: A lens system comprising, at locations in the vicinity of each other, radial type graded refractive index lens elements made of a medium having a positive refractive power and other radial type graded refractive index lens elements made of a medium having a negative refractive power. This lens system has aberrations corrected favorably with the radial type graded refractive index lens elements which are made of materials easily preparable.

Abstract: An optical information reading apparatus wherein the intensity distribution of a light beam projected onto a video disk through an objective optical system is so made that the intensity in the direction along an information track is larger than the intensity in the direction intersecting at right angles with the information track in order to improve S/N and to eliminate cross-talks.

Abstract: A method and an apparatus for detecting a focussing error signal and a tracking error signal of an objective lens with respect to an information track of a video disc on which a reading light spot is focussed by the objective lens includes a detection prism having a reflection surface which is set substantially at a critical angle and a light detector for receiving the light flux reflected by the reflection surface. The light detector is arranged in a far field of the track and having four light receiving regions divided along two orthogonal directions. The focussing error signal is derived as a difference between output signals from the regions aligned in a track direction and the tracking error signal is derived as a difference between output signals from the regions aligned in a direction perpendicular to the track direction. An information signal is obtained as a sum of the output signals from the four regions.

Abstract: A playback optical system for video discs comprising a light shield plate arranged in the vicinity of the pupil of the read-out lens, said optical system facilitating design of said read-out lens and permitting adjustment of focal length.

Abstract: A light absorptive film comprising a first sub-film and a second sub-film each including at least one dielectric layer and at least one metallic layer which have anti-reflecting functions even when used independently and arranged oppositely on both sides of another dielectric layer. Said light absorptive film exhibits anti-reflecting effect for light incident on said first sub-film and said second sub-film.

Abstract: A high resolution image forming optical system provided with an annular aperture stop arranged near the front side focal plane of a condenser lens and an annular filter arranged in a position conjugate with the annular aperture stop with respect to the optical system including the condenser lens and an objective in order to improve the image-forming performance.

Abstract: In a signal detecting system in an optical information reading apparatus wherein, in order that a tracking signal having few errors can be obtained, the pupil of an objective used to project a light from a light source as a spot onto the information recording track of a disk, collect the light reflected on the disk and lead it to a light receiving device is covered in the form of a band or a cover plate placed in front of detectors of the light receiving device to intercept a part of the light entering the dectector.

Abstract: A light absorptive film comprising a light absorptive metallic layer and layer of dielectric material arranged on the incidence side of said light absorptive metallic layer, said light absorptive film being so adapted as to reduce reflection on said metallic layer by composing it in such a manner that the reflected wave produced at the boundary surface between said metallic layer and said layer of dielectric material is canceled by the reflected wave produced at the boundary surface of the other side of said metallic layer.