Abstract: For manufacturing monaspherical lenses, a correction layer of a synthetic resin is provided on a substrate having a spherical surface. In this method, centering is performed by using the curvature of the surface of the matrix. With a correct choice of the radius of curvature of the substrate surface, the substrate approaches the matrix most closely near a collection of inflection points in the matrix surface situated on a circle. A good centering without a guiding mechanism is possible by using the method according to the invention. Moreover, the differences in thickness in the correction layer are small enough to prevent shrinkage defects upon curing of the synthetic resin layer.

Abstract: A photomultiplier tube which is insensitive to high magnetic fields comprises a photocathode deposited on a transparent window at the end of an insulating casing. The multiplier tube comprises a single amplifier stage comprising a dynode. The dynode is a metallic sheet with a circumference substantially surrounding the photocathode. A layer of a secondary emissive material is provided on the inner face of the dynode. An anode is formed of a metallic grid which is homeomorphous to the surface of the dynode. The anode is placed parallel to and at a short distance from the inside surface of the dynode.

Abstract: A device for projecting the image of a reticle in an optical system whose line of sight is represented by the reticle. The collimator is situated at the edge of the pupil of an objective of the optical system. The optical axes of the objective coincides with the line of sight. According to the invention, the collimator comprises two subcollimators arranged along respective orthogonal axes perpendicular to the optical axis. Each collimator forms an image of a radial slit in such a way that the intersection of the two slit images is situated on the line of sight. In this way, focussing error does not give rise to an angular displacement of the line of sight.

Abstract: An ultrasonic sector scanner includes first and second magnetizable stators spaced on a longitudinal axis. First and second rotors are provided in the gaps between the end faces of the first and second stators, respectively. The rotors have tapered surfaces spaced from the end faces of the stators to form gaps therebetween. The gaps between the first rotor and the end face of the first stator decrease as the rotor rotates in a first direction. The gaps between the second rotor and the end faces of the second stator decrease as the rotors rotate in a second direction opposite the first direction. An ultrasonic transducer is connected to the rotors and arranged to be rotatable with the rotors. A servo-control system is provided to cause the rotor/transducer assembly to rotate according to a prescribed reference signal.The ultrasonic sector scanner has a cover assembly in which a flexible membrane is provided with ribs which engage grooves in the wall of the housing.

Abstract: A lens is produced having one aspherical surface which is accurately axially aligned with a spherical or flat surface on the opposite side of the lens. The aspherical surface is produced with a mold. The mold has a molding surface having an accurate negative profile and the desired finish of the required aspherical surface.The mold is on a rotatable jig. By means of adjustment screws the mold is adjusted to correct misalignment of the axis of the molding surface and the axis of rotation of the jig. Misalignment is detected by directing a collimated light beam onto the molding surface so that it is reflected onto a screen. When the mold is rotated, the light beam moves on the screen until the molding surface is properly aligned with the axis of rotation.A preformed glass substrate has one aspherical surface of approximately the desired profile and finish and on its opposite side a spherical or flat surface.

Abstract: A pyroelectric infrared radiation detector which is particularly suited to automated assembly comprises a pyroelectric detector element mounted in a housing having a window transparent to infrared radiation. Electrically conductive leads in a single-in-line configuration extend through a base portion of the housing for making external electrical connections to the detector. One lead has an extended portion within the housing. The extended portion provides a cantilever support to which the detector element is fastened. The leads may all be formed from portions of a unitary lead frame. A second differentially connected pyroelectric detector element may be fastened to another cantilever support formed by a portion of the same lead frame. The cantilever supports preferably extend from an insulating block which encapsulates an associated electrical component and which also provides support for the detector elements.

Abstract: The invention improves the safety in the case of breakage of an endless chain whereby a part of an X-ray apparatus table top is supported and displaced by a chain. The chain is accommodated inside a rigid guide having a slot through which the chain is coupled to the table top. The guide is constructed so that the chain has only a limited freedom of movement on all sides.

Abstract: A master suitable for the manufacture of electroplated negative metal copies. The master comprises a preform which on at least one side has a layer of electroplated aluminum. The surface has a precisely machined profile and is coated with a titanium nitride layer.

Abstract: A sheath for light waveguides. The sheath consists of a tube loosely surrounding one or more light waveguides. In a neutral bending plane, longitudinal elements are provided for absorbing tensile and compressive forces. The coefficient of expansion of the longitudinal elements corresponds to that of the light waveguides. The longitudinal elements are form-coupled and force-coupled to the tube.

Abstract: The invention relates to a method of manufacturing an optical grating from a body having a surface which is provided with equidistant grooves. In order to obtain cheap and deformation-resistant gratings, according to the invention a surface of a substrate is provided with a number of layers of substantially equal thicknesses. The etching rates of the layers (in a given etchant) increase substantially proportionally to the number of the layer. A cross-sectional surface of the layers is then exposed to the etchant to form the surface with the grooves.

Abstract: Television camera tube comprising a tubular envelope of glass drawn on a mandril and having an internal conductive wall coating. A diaphragm having an aperture is supported in the envelope by a supporting surface extending transverse to the longitudinal axis of the envelope. The supporting surface is formed by a substantially stepwise change in the internal transverse dimension of the envelope. The conductive wall coating is interrupted at a distance from the diaphragm. The stepwise change in the internal transverse dimension of the envelope portion taking place in at least a first a step and second step. The first step forms the supporting surface for the diaphragm. The interruption (6) in the conductive wall coating is provided on the second step. If the diaphragm in such a tube is a flat plate and the distance d between the first step and the second step is between 0.4 D and D, where D is the inside diameter of the envelope between the first and the second step, the axial astigmatism.

Abstract: The invention relates to an X-ray unit which can be swivelled about a horizontal axis. The table is moved by a lever arrangement in which the longitudinal position of the table is a function of the swivel angle so that a greater low head position can be achieved.

Abstract: A method of manufacturing ceramic sintered bodies. A basic starting material corresponding to the sintered body is mixed with compounds which form a melting phase with the starting material during sintering. Prior to the sintering, presintered starting material nuclei having an average crystallite size which corresponds at least three times the average crystallite size of the basic starting material are added to the basic material and melt-forming compounds. The nuclei are added in a quantity of at least 0.1% by weight of the starting material to be sintered. By this addition the grain size and grain distribution in the ceramic sintered body of materials with discontinuous grain growth can be effectively checked and controlled.

Abstract: In a television camera having at least one pickup tube, it is desirable to generate an electron beam with a current intensity which is greater than that necessary for obtaining a picture signal with a nominal amplitude between a black level and a white value. This prevents comet tails from being produced on the display behind brighter, moving scene portions. The electron beam intensity is adjusted by blanking the electron beam periodically during at least one field period and within the field period during at least a portion of a line period of a number of consecutive lines. The electron beam is properly set when the picture signal amplitude is observed to be maximum at a substantially minimum beam current intensity.

Abstract: A collimator lens has a small numerical aperture and a specific focal length. One of the surfaces of the lens is planar and the other surface is aspherical. The aspherical surface is defined by a series expansion with only a few even terms.

Abstract: An ultrasonic scanning apparatus includes a rotor, first and second electromagnetic stators, and an ultrasonic transducer mounted on the rotor. Each electromagnetic stator has two curved pole faces arranged opposite pole faces on the rotor. The electromagnetic stators are arranged on opposite sides of the axis of rotation of the rotor. The stator pole faces are tapered such that on rotation of the rotor in one direction, the gaps between the rotor and a first stator decrease while the gaps between the rotor and the other stator increase. On rotation of the rotor in the opposite direction, the gaps between the rotor and the first stator increase and the gaps between the rotor and the second stator decrease. Means are provided for alternately energizing the first and second electromagnetic stators to cause the rotor to oscillate about the axis of rotation.

Abstract: The invention relates to a compound blazed optical phase grating. The grating comprises at least two grating sections which are disposed opposite each other in parallel planes. The gratings have grooves which extend parallel to each other. The grating sections have equal grating periods and are movable relative to each other within their planes and perpendicular to the grooves. Over one grating period, the optical path length varies at least substantially parabolically and symmetrically relative to the grating period. The path length varies in such a manner that when both grating sections are symmetrically arranged relative to a common line perpendicular to the grating planes, the optical path length through the compound grating is uniform across the grating. Various optical switches and switching matrixes can be formed by using such compound phase gratings.

Abstract: A thermomagnetooptical memory device comprises a recording medium having a substrate on which there is a magnetooptically active layer. The magnetooptically active layer is present between a laser source and a layer reflecting radiation from the laser source. The device further includes lenses to focus radiation from the laser source onto selected locations on the recording medium, and magnetooptical detectors placed in the path of the radiation returning from the magnetooptically active layer. The magnetooptically active layer comprises a polycrystalline, oxidic material based on Fe.sup.3+ having a spinel structure and having a thickness chosen to cause destructive interference between the plane polarized radiation returning from the surface of the magnetooptic layer and plane polarized radiation returning from the reflecting layer and having passed through the magnetooptically active layer at least twice.

Abstract: A method of manufacturing an optical cable element in which a synthetic resin envelope is extruded around one or more optical fibers at elevated temperature. The element is then cooled and wound on a reel in which, after cooling, the element is again heated and maintained (tempered) at the heating temperature to irreversibly shrink the synthetic resin envelope.

Abstract: In a magnetic layer of a magnetooptical modulator having fixed magnetic single domain areas, the areas of the layer present between the single domain areas are made electrically conductive by reduction.