Abstract: A record carrier is described having an optically readable information structure comprising information areas arranged in information tracks and spaced from each other by intermediate areas. The information areas have a first, comparatively large, phase depth and the intermediate areas have a second, comparatively small, phase depth thereby providing an optimum information signal and an optimal tracking signal during reading.

Abstract: A photodetector for use in an angular displacement measuring apparatus consists a multiple photocell consisting of radially extending strip-shaped photodiodes (11 to 15). According to the invention, the diodes are connected alternately via switching electrodes (7) to an output electrode (6), which is constituted by a conductive image-defining shield arranged above the switching electrodes and comprises two opposite bands (AB, CD), whose widths (b.sub.1, b.sub.2) are substantially inversely proportional to their radii of curvature in order to reduce trouble by cross-talk. The photodetector may be an integrated circuit, which comprises besides the multiple photocell also a part of the processing circuit. The invention also relates to an apparatus for measuring angular displacements by means of such a photodetector.

Abstract: Displacement of an object is sensed by a transducer element having light first strips and dark second strips alternating in a direction of object displacement. The first strips are formed as phase gratings having grating lines extending in the direction of displacement and having a width equal to half the grating period and a depth such that the zero-order diffraction beam is suppressed. The lines may be grooves or ribs, separated by lands which are at the same level as the second strips. A device, for measuring displacement of an object on which such an element is fixed, includes an imaging system having an aperture limited such that first and higher-order diffraction beams from the phase grating are not transmitted to a radiation-sensitive pattern detection system.

Abstract: A method of manufacturing a semiconductor device, in which there is applied to a surface of a semiconductor substrate a base layer of photosensitive lacquer, which is coated with a top layer of photosensitive lacquer. By means of a first patterned irradiation, there is formed in the top layer a mask of which a contact copy is formed in the base layer during a second irradiation. A material which can be discolored is used for the top layer. During the first irradiation, the top layer is locally discolored, whereupon the layer thus discolored is used as a mask during the second irradiation. By the use of the discoloring top layer, additional processing steps, which would ensure from a wet development of the top layer, are avoided.

Abstract: The method of the present invention involves the forming of a depression with sidewalls extending below a first oxidation mask provided on a surface of a silicon body. Subsequently, after the sidewalls of the depression have been provided with a second oxidation mask, an oxidation treatment is carried out. According to the invention, the depression is provided in such a manner that the sidewalls of the depression are flat and form an angle of 25.degree. to 45.degree. with the original surface of the silicon body. The second oxidation mask is formed by a 5 to 50 nm thick layer of silicon nitride or silicon oxinitride applied directly or separated from the surface by a layer of silicon oxide having a thickness of less than 5 nm. This leads to a very flat structure.

Abstract: When two indirect only slightly different semiconductor materials having a suitable band gap, for example, AlAs and Al.sub.0.8 Ga.sub.0.2 As, are grown epitaxially one onto the other in layers of a few unit cell layers thick, the electronic band structures are folded so that the indirect minimum of the conduction band is displaced from the edge of the Brillouin zone to the center. The two indirect materials then constitute a superlattice with a band transition with a band gap of 2.2 eV.

Abstract: A record carrier is disclosed in which information is recorded in an optically readable information structure of track-wise arranged information areas which alternate with intermediate areas. Adjacent information track portions are situated at different, parallel planes spaced from each other by a predetermined distance such as to reduce crosstalk from neighboring tracks thereby permitting the information density to be substantially increased.

Abstract: An apparatus is described for accurately measuring the profile on an object. The apparatus comprises two probes for simultaneously scanning the object to be measured and the reference object, the objects being rotatable about the same axis. Each of the probes is provided with a reflecting element, which are respectively incorporated in the measuring arm and reference arm of an interferometer.

Abstract: A record carrier is disclosed having an optically readable information structure comprising trackwise arranged information areas, as well as an apparatus for reading said record carrier. By using two mutually perpendicularly polarized beams components for reading and by giving the information areas of adjacent track portions a different geometries such that areas of one geometry can be read in an optimum manner by only one of the beam components and is virtually not observed by the other beam component, the track distance can be reduced without increasing the crosstalk, so that the information content of the record carrier is increased.

Abstract: A record carrier is described in which information is recorded in an optically readable information structure comprising trackwise arranged information areas; as well as an apparatus for reading said record carrier. By arranging the adjacent information track portions on different slopes the track spacing can be reduced without increasing crosstalk.

Abstract: A record carrier is described having an optically readable radiation-reflecting information structure, which comprises trackwise arranged information areas which, in the track direction and transverse to the track direction, are spaced from each other by intermediate areas. It is demonstrated that if the angle of inclination between the walls of the first areas and the normal to the record carrier has one value between 30.degree. and 65.degree. for a satisfactorily reproducible record carrier, the geometrical distance between the plane of the information areas and the plane of the intermediate areas should have one value between (165/N) nanometers and (270/N) nanometers, N being the refractive index of a transparent medium which is disposed between the first and the second plane.

Abstract: A record carrier is described having an optically readable radiation-reflecting information structure, comprising information areas arranged in information tracks, which areas are spaced from each other by intermediate areas, the information areas having oblique walls. It is demonstrated that a suitable information signal and a suitable positional error signal are obtained if the angle of inclination of the walls of the information area lies between 65.degree. and 85.degree. and the phase depth of the information areas lies between 95.degree. and 140.degree..