Abstract: A signal detecting apparatus in an optical disc apparatus having an objective lens which converges light emitted from a light source onto an optical disc and a condenser lens which converges light reflected by the optical disc and transmitted through the objective lens includes first and second light receiving elements, each having a light receiving surface located before or behind a convergence point on which the light reflected from the optical disc is converged when the objective lens is in a focal position. Each of the light receiving surfaces are split into at least four light receiving areas.

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: An objective lens system comprising four pieces lens arranged from a light source side, in order, a cemented lens which has a convex first lens and negative second lens cemented with each other, a convex third lens and a positive meniscus forth lens where convex surface thereof is faced toward the light source side.

Abstract: An object lens system consists of a converging lens which has both surfaces formed of a convex aspherical surface and having a radius of curvature which is increased as it goes toward the periphery from the center thereof, and a chromatic aberration correcting element having almost no power disposed towards said light source side of said converging lens and adapted to correct a chromatic aberration of said converging lens.

Abstract: An image blur compensating telephotographic lens has four lens groups. The four lens groups comprise a first lens group having a positive power, a second lens group having a negative power, a third lens group having a positive power, and a fourth lens group having a negative power arranged in this order from an object side. In one embodiment, the telephotographic lens has a lens moving mechanism for moving the second lens group in a direction vertical to the optical axis in order to compensate for an image blur when a photograph is taken. In another embodiment, the telephotographic lens has a lens moving mechanism for moving the third lens group in a direction vertical to the optical axis in order to compensate for an image blur when a photograph is taken.

Abstract: A collimator lens for an erasable and re-recordable magneto-optical disk system comprising a first positive lens, a second positive lens and a third negative lens arranged from a light outgoing side in order. The second and third lenses are cemented together and the cemented lens has a positive power. A refractive index of the first lens n1 is lower than 1.686.

Abstract: A zoom lens has three or more lens groups. A variable power lens group or at least one lens group located in a position nearer to an image than a variable power lens group serves as an image blur compensating group which is displaceable with respect the remaining lens groups. The magnification m.sub.C of the image blur compensating group satisfies a relation with respect to a composite focal length f.sub.1 of the lens groups nearer to an object than the image blur compensating group such thatm.sub.C =1/{1+(f1/A)}wherein A is an arbitrary constant.

Abstract: A telephoto lens system utilizing an inner focusing method, for use in a 35-mm single-lens reflex camera, and despite its lightweight, compact size ensures high performance, and which performs focusing by moving only one lens unit. Performance of the telephoto lens system includes: having a telephoto ratio of no more than 0.7, yet compensating for aberrations when focused upon an object at infinity; adopting an inner focusing method, yet being capable of focusing at the closest distance which is no greater than 7 times the focal length for infinity; and performing near focusing without causing great aberrational variations. The telephoto lens system, in order from the object side, includes: a first lens unit having a positive refractive power; a second lens unit having a weak refractive power; and a third lens unit having a negative refractive power, and which performs focusing for an object at a finite distance by movement of the third lens unit.

Abstract: Herein disclosed is a parallel beam shaping optical system which is an afocal anamorphic optical system. The optical system comprises two prisms for shaping a bundle of beams in a desired direction. The optical system is constructed so that an incident light is in parallel to the emergent light. Two shaping optical sub-systems each composed of the above-described optical system may be combined with each other to obtain a desired shaping of a ray of light.

Abstract: A front conversion adapter which can be attached to the front face of a lens shutter type of camera having a zoom lens and a finder optical system, wherein a lens frame of the zoom lens moves in accordance with the zooming operation. The front conversion adapter has an adapter body which can be attached to a camera body, and a conversion optical system which is located in front of the zoom lens and which moves in the optical axis direction thereof to change the focal length of the zoom lens. The conversion optical system is supported by an adapter lens frame so as to move in the optical axis direction in association with movement of the lens frame of the zoom lens and in accordance with zooming operation.

Abstract: A four-group type telephoto lens system including a super-telephoto range having a viewing angle (2.omega.) of less than 8.degree. and which includes a focusing lens in a first lens group. The lens system includes for lens groups. The first group is composed of a first sub-part having a positive refractive power, a second sub-group having a negative refractive power, and a third sub-group having a positive refractive power. The second group has a negative refractive power, the third group a positive refractive power, and the fourth group a positive refractive power. Zooming is effected by moving the second group, while focusing is carried out by moving only the third sub-group of the first group.

Abstract: A rear attachment lens mounted between a master lens and an image plane for increasing the composite focal length. It consists of four lenses. The first lens is negative and has a concave surface on the image side. The second lens is positive, convex on both sides and cemented to the first lens. The third lens is negative and is concave towards the master lens. The fourth lens is positive, convex towards the master lens and has at least one aspherical surface. Preferably five numerical conditions on magnification, refractive indices, radius of curvature and asphericity are satisfied.

Abstract: An in-line stripe type color picture tube comprises an inner magnetic shield member having sufficient shield effect against both individual vertical and horizontal components of the earth magnetism and composite components as well. The inner magnetic shield member prevents unwanted shifts of electron beams to ensure that the positional relationship between a fluorescent screen and landing electron beams may have sufficient tolerances and color blur on the fluorescent screen may be prevented.

Abstract: A color misalignment correction device for use in a color picture tube, in which at least two magnets are disposed rotatably and adjustably on the outer peripheral surface of the cathode-ray bulb so as to correct an arc-shaped convergence error appearing in a horizontal direction of the phosphor screen due to a mounting error of the electron guns in the color picture tube or due to a mounting error of the deflection coil assembly on the color picture tube.

Abstract: A color picture tube of an in-line type comprises means for deflecting beams of electron emitted from electron guns of the in-line type aligned horizontally such that for the horizontal deflection, the central beam is subjected to a greater deflection than side beams and for the vertical deflection, the side beams are subjected to a greater deflection than the central beam. Two vertical magnetic pole piece plates which are long vertically and thin horizontally are so disposed as to sandwich the central beam near the outlet of the central electron gun in order to weaken horizontal deflection magnetic field acting on the central beam, whereby a portion of the horizontal deflection magnetic flux acting on the central beam is absorbed by the two magnetic pole piece plates. The vertical deflection magnetic field is almost not affected by these vertical magnetic pole piece plates.

Abstract: The correcting lens comprises a plurality of regions which are formed at at least one portions of the effective surfaces on both sides of the lens by means of a plurality of border lines which are discontinuous in only one direction. The regions on one side are inclined in a direction different from that of the regions on the opposite side of the lens.

Abstract: The correcting lens comprises a plurality of regions which are formed at at least one portion of the effective surfaces on both sides of the lens by means of a plurality of border lines which are discontinuous in only one direction. The regions on one side are inclined in a direction different from that of the regions on the opposite side of the lens.

Abstract: In light exposure apparatus wherein the face plate of a color picture tube is exposed to the light from a light source through a swinging illumination intensity correcting filter, a correction lens and a color selection electrode, the effective surface of the illumination intensity correcting filter comprises a plurality of regions having different light transmitting ability, and the effect of the optical characteristics at the interfaces between the regions is arranged and substantially eliminated by the swinging motion of the illumination intensity correcting filter.

Abstract: In a correction lens wherein the effective surface thereof has at least a lens member having no island shaped portion, said member being defined by the step shaped border line never closing by themselves to form an island shaped lens segment on said correction lens surface.