U.S. Philips Corporation

Gijsbertus Bouwhuis

Josephus J Braat

Hendrik De Lang

Johannes Van Der Wal

Carel Arthur Simons

Jan Haisma

Johannes H Spruit

Bernardus A Jacobs

Peter Ferdinand Greve

Adrianus J Franken

Cornelis M Van Uijen

Antonius H Holtslag

Werner A Heijnemans

Kornelis A Immink

Christiaan H Velzel

Antonius H Akkermans

Theodorus F Lamboo

Klaas Compaan

Pieter Kramer

Nicolaas H Dekkers

Guido C Van De Looy

Teunis J Hazerdonk

An image pick-up device with an electronic image sensor (IS.sub.1 IS.sub.2) is described, which includes a matrix of sensor elements (SE) and a low-pass filter for suppressing image frequencies exceeding the sampling frequency of the sensor. The low-pass filter has a first, composite filter function (F.sub.com) consisting of a variable component and a constant component and the device has a second filter function (F.sub.c) in conformity with the constant component which is optically or electronically subtracted from the first filter function.

Image pick-up device

A device for detecting a centering error of a rotationally symmetrical surface (0.sub.1, 0.sub.2) of an object (0) with respect to a rotational axis (AR) about which axis the object is rotated for the purpose of the centering error detection is described. Two beams (b.sub.1, b.sub.2 ; b.sub.3, b.sub.4) at angles of approximately 90.degree. are directed onto the object and the variation in the phase difference caused by the centering error (.epsilon.) between the two beams (b.sub.1, b.sub.2 ; b.sub.3, b.sub.4) reflected by the surface is determined.

Interferometric device for detecting a centering error

Recording and/or reading of information on an optical record carrier is effected by scanning such record carrier with a radiation beam which is focussed by an objective lens into a scanning spot of a size which is diffraction-limited by the aperture of the objective lens. The effective size of the scanning spot is considerably reduced by including a layer of non-linear optical material in the record carrier, such material having an optical characteristic which changes with changes in intensity of the radiation incident thereon. The read/write resolution of information on the record carrier is thereby substantially increased.

Optical record carrier and method and apparatus for increasing the

The volume of the housing of a rear-projection system can be reduced by 20 to 25% when the light beam is obliquely incident on the projection screen. The obliquely incident light beam is deflected towards the viewing space by means of a prism plate (731). By dividing the light-refracting action of the prism plate between the front and rear of the plate only minor light loss occurs.

Compact rear-projection system with obliquely incident light beam

A device is described for detecting a magnification error in an optical imaging system comprising a lens system (L.sub.1, L.sub.2) which is telecentric at one side. Two gratings (RG.sub.1, RG.sub.2) arranged in the object plane (MA) are imaged onto two gratings (WG.sub.1, WG.sub.2) arranged in the image plane (W; WT) and the radiation beams (b.sub.1, b.sub.2) by means of which these images are formed are incident on two radiation-sensitive detection systems (D.sub.1, D.sub.2) which supply periodic signals (S.sub.1, S.sub.2). By phase comparison of these signals a magnification error (S.sub.ME) and, if desired, a focussing error can be measured very accurately.

Device for detecting a magnification error in an optical imaging system

In a device for displaying three-dimensional pictures, N (with N=2, 3, 4 . . . ) recorded images corresponding to different spatial observation positions are displayed on one or more intermediate display screens (3, 4, 5, 82, 83, 84). The device comprises a viewing screen (6) having lens elements (20, 30) via which corresponding picture segments of the recorded images are displayed. An optical coupling (8, 44) having a plurality of light conductors (8) exists between the viewing screen and the intermediate display screen(s). The light conductors unambiguously associate groups of N corresponding picture segments with lens elements of the viewing screen. By means of the device, three-dimensional pictures can be observed without further auxiliary means for the viewer.

Device for displaying three-dimensional images

An apparatus is described for point-by-point scanning of an object, which may be a phase object, an amplitude object or a combined amplitude and phase object. The object is scanned with a light, sound, electron or X-ray beam which is converged to a spot on the object. A pair of detectors disposed in the path of the modulated radiation coming from the object convert the variations in the radiation into corresponding electrical signals which are fed to a summing circuit. A variable phase shifter connected between at least one of the detectors and the summing circuit is used to introduce a phase shift in the electrical signal such as to optimize the output signal of the summing circuit for the type of object being scanned.

Apparatus for the point-by-point scanning of an object

A device is disclosed for processing optical information comprising a system of optical elements (6, 7, 9, 10, 12, 13) arranged along an optical main axis (11) for guiding a light beam (4) to a radiation-sensitive detection system (8) at least one coma correction plate (13, 20, 21) is provided in the system of optical elements and comprises a substrate having a dielectric layer varying in thickness so as to at least partly compensate for axial coma due to differences in path length of the light rays. Also disclosed is a method of manufacturing such a coma correction plate in which during the vapor deposition of the dielectric layer, a plate-shaped substrate (31) is moved at a constant speed below a template (33) parallel to an axis (34) which is situated in the plane of the template. The template (33) is situated between the vapor deposition source (30) and the substrate (31) and has an aperture (34) which is divided by the axis. A part (36) of the edge of the aperture on either side of the axis varies as a third power function of the distance to the axis, the point of intersection (37) of the axis with the part of the edge being taken as zero point.

Device for processing optical information and method of manufacturing a

In a scanning electron microscope, a periodic structure in the object plane is used for the detection of the focus condition of a spot-focussed electron beam scanning an object in order to correct defocusing and astigmatism in the scanning electron beam spot. To achieve this the detector comprises a plurality of individual elements which can be pair-wise read and an electronic circuit for forming a control signal for controlling the excitation of a spot-forming lens and a stigmator, respectively, from signals representing movement of the electron interference pattern at the detector, relative to the object scan, due to an out of focus condition. The signals are derived from corresponding pairs of detector elements which are situated at a fixed distance from each other in order to correct the focus and compensate for the astigmatism in the electron beam respectively. In the case of astimatism, signals from at least two pairs of detector elements spaced in directions at right-angles to one another, are used.

Automatic beam correction in a scanning transmission electron microscope

A method and arrangement for aligning a mask comprising a mask-pattern relative to a substrate when the mask-pattern is repeatedly and directly imaged on the substrate, gratings in the mask and gratings on the substrate (phase gratings) being employed as alignment references. The gratings in the mask are located outside the mask pattern and the phase gratings are located on the substrate outside the area where the mask-pattern is imaged. The substrate (phase) gratings are imaged on one of the mask gratings with a projection system which is also used for projecting the mask-pattern on the substrate. The image of the gratings on the grating in the mask is adjusted. Thus, a very accurate alignment can be achieved.

Method and arrangement for aligning a mask pattern relative to a

An apparatus is described for the pointwise scanning of an information surface. By arranging an observation objective system asymmetrically relative to a zero-order subbeam of the radiation coming from the information surface, and by utilizing a detector whose dimension in the scanning direction is small, the resolution can be increased.

Apparatus for the pointwise scanning of an information surface

An opto-electronic focussing-error detection arrangement is described for the detection of a deviation between a radiation reflecting surface and the plane of focussing of an objective system. In the path of the beam which is reflected by the surface a beam-splitting element is disposed and behind said element two radiation-sensitive detectors are arranged which are each associated with one of the subbeams formed by the beam-splitting element. The detectors are grating-shaped detectors and are effectively divided into two detector sections by selection devices, the bounding line being adjustable. A focussing error signal is obtained which is highly independent of a positional error of the radiation-sensitive detection system relative to the beam axis.

Opto-electronic focussing error detection arrangement

A record carrier is described on which information is stored in an optically readable structure of trackwise arranged areas and intermediate areas. By giving the information tracks periodic excursions towards and away from adjacent tracks, in a direction transverse to the direction of reading, the period of the excursions being substantially greater than the average period of the areas and the amplitude of the excursions being smaller than the width of the tracks, a control signal for centering the read beam of radiation on an information track can be obtained without the use of additional optical means. The excursions of the tracks have such relative phase that the tracks are in nested concentric relation and one component of the stored information represents the phase of the undulations.

Videodisc with undulating nested tracks

A gas discharge laser includes one or more birefringent layers in a multi-layer reflector that provides such a large difference in reflection of light polarized linearly in two mutually perpendicular directions that the laser generates 100% linearly polarized light in one direction only. In the other directions the reflection is insufficient to obtain stimulated emission.

Gas discharge laser for generating linearly polarized radiation

A gas discharge laser comprises a multilayer coupling-out mirror including a plurality of alternate dielectric layers of high (H) and low (L) indices of refraction. A radiation-attenuating film element, preferably a metal film, is sandwiched between a pair of L dielectric layers located near the mirror substrate to provide an asymmetrical characteristic whereby the laser becomes relatively insensitive to light reflected towards it, which in turn reduces any tendency toward fluctuation in the intensity of the laser beam. The device is especially useful in systems for reading out information from a video record carrier wherein the reflected light is modulated and if returned to the laser would produce output power fluctuations therein.

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Eindhoven, Netherlands

Gijsbertus Bouwhuis