U.S. Philips Corporation

Klaas Compaan

Pieter Kramer

Gijsbertus Bouwhuis

Jan Roos

Joannes Gregorius Bremer

Adrianus Cornelius Van Kasteren

Maarten R De Haan

Leopold H Hissel

Robert Franz Forsthuber

Robert F Forsthuber

An optical measuring system for determining angular displacements of an object, including a radial grating connected to the object. Optical elements including two straight-line-generatrix surfaces focus the grating image as a parallel grating image onto a linear array radiation-sensitive detection system. The linear array may be photodiodes functioning as a grating-like element.

Shaft encoder with an optical system comprising two

An optical focusing error-detection device is disclosed which comprises a radiation-sensitive detector with four sub-detectors, and an astigmatic lens system arranged between the detector and the objective system whose focusing-error is to be detected. The astigmatic system is arranged in a non-collimated beam and comprises two cylindrical lenses having mutually perpendicular axes and having different powers so that the resulting focusing-error signal is symmetrical and linear around the zero point.

Optical focusing-error detection device

Disclosed is a record carrier for storage of digital data which is provided with a first periodic track variation having a period corresponding to a frequency at which the power spectrum of the digital signals is at a zero level. The first track variation produces a corresponding modulation of the radiation when scanned by a beam so that a clock signal can be derived from the detected radiation for synchronizing readout or recording of the data. The record carrier is further provided with a second periodic track variation in a direction transverse to the track direction having a period of the same order of magnitude, and preferably equal to the period of the first periodic track modulation. The second track variation produces a corresponding modulation of the beam which is detected and is used to generate to a tracking signal, the clock signal being used as phase reference signal for demodulation of the tracking signal. If the periods of the two track variations are equal, low-pass filtering automatically yields the tracking signal.

Optically readable record carrier with track variations which provide

An apparatus is described for converting cinematographic images into video signals. The film gate in which a frame to be scanned is located is illuminated uniformly. The film is scanned by means of a rotatable scanning mirror, which with the aid of an imaging system images one line of the film frame onto one row (three rows for color film) of radiation sensitive detectors. The detectors of a row are read sequentially. The illumination beam has a large aperture angle in a first plane transverse to the direction of film transport and a small aperture angle in a plane transverse to the first plane. The film movement is detected with the aid of a sprocket hole detection system, in which an elongate narrow light spot, whose longitudinal direction is transverse to the direction of film transport, is projected onto the strip of film with the sprocket holes. The position of the scanning mirror is detected with the aid of two gratings of special shape.

Apparatus for converting cinematographic pictures into video signals

Apparatus for reading a record carrier provided with a spiral structure in which sound and/or image information is stored in the form of frequency modulated or phase modulated signals is disclosed. The carrier structure is composed of coplanar regions of variable length separated by coplanar areas of variable length. Where the regions and areas are all in the same plane the regions and areas have different coefficients of reflection or transmission. Where the regions and areas are not coplanar they are spaced by a distance sufficient to produce in response to impinging radiation a one-half wave length difference in the radiation exiting the regions and areas. The apparatus provides a light beam with a frequency that facilitates diffraction of the beam by the areas and regions, and also provides a radiation sensitive detection system for converting the light beam modulations caused by the record carrier into a corresponding electrical signal.

Apparatus for optically reading a phase-modulated optical record carrier

A carrier is provided with a spiral structure in which sound and/or image information is stored in the form of frequency modulated or phase modulated signals. The carrier structure is composed of coplanar regions of variable length separated by coplanar areas of variable length. Where the regions and areas are all in the same plane the regions and areas have different coefficients of reflection or transmission. Where the regions and areas are not coplanar they are spaced by a distance sufficient to produce in response to impinging radiation a one-half wave length difference in the radiation exiting the regions and areas. Apparatus for imaging the radiation exiting the carrier structure is also disclosed.

Video disc with phase structure

An apparatus is described for reading, by means of a beam of radiation, a disk-shaped information carrier which contains spirally arranged video and/or audio signals coded in optical form, which apparatus comprises a source of radiation and a radiation-sensitive signal detector cell, the information carrier being disposed in the radiation path between this source and this detector. By providing at least one grating, consisting of radiation-transmitting and radiation-absorbing stripes and on which an image of part of the grating-shaped structure of the information track in the vicinity of the portion of this track to be read may be formed, and a radiation-sensitive detection system, an accurate indication of axial and radial displacements of the optical imaging system relative to the information carrier can be obtained.

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Eindhoven, Netherlands

Klaas Compaan