Bbc Brown, Boveri & Company, Limited

Bbc Brown Boveri Ag

Imperial Chemical Industries Limited

Abb Research Ltd.

Asea Brown Boveri Ag

Asea Brown Boveri Inc.

Gretag Systems, Inc.

Jurgen Nehring

Meinolph Kaufmann

Klaus Bohnert

Terry J Scheffer

Hermann Amstutz

Walter Kraft

Paul A Holmes

Rino Doriguzzi

Markus Egloff

Alan Nevin

Hanspeter Schad

Karl Kloti

In order to detect, in particular, a high electric voltage (8), use is made of an electrooptic sensor with an electrooptic crystal (4) such as is applied in Pockels cells. Light is irradiated into the electrooptic crystal (4) in a linearly polarized fashion from a light source (L) via a fiber coupler (FK), a fiber-optic cable (F1), a collimator (K1), a 1st polarizer (P1), a beam splitter (1), and 1st and 2nd glass plates (2, 3). Located at the end face of said crystal is a 3rd glass plate (5) having a layer electrode (6) which simultaneously acts as a mirror (7) and retroreflects the incident light through the electrooptic crystal (4). One component beam (T1) of the reflected light passes back to a 1st light detector (D1) via the beam splitter (1) and the 1st polarizer (P1), now acting as an analyzer. A 2nd component beam (T2) passes to a 2nd light detector (D2) via a .lambda./4-delay plate (9), a 2nd polarizer (P2), a 90.degree. prism (10), a collimator (K2) and a 2nd fiber-optic cable (F2). Light intensities (I.sub.1) and (I.sub.2) are evaluated by means of a microprocessor (14). Owing to the fact that the two phase-shifted light signals are derived from a common optical channel, an intrinsic birefringence of the electrooptic crystal (4) does not affect their phase difference. A 9.degree. prism can be used instead of a mirror (7) for reversing the light. Input and output channels of the light can be separate. Ways are specified for the temperature compensation of a measurement result signal (S).

Method and device for the optical determination of a physical quantity

A photographic color copying apparatus and an exposure control process includes measuring filters variable as a function of the spectral sensitivities of different copy materials, in particular electro-optical filters. The variable measuring filters are constructed in the manner of Solc filters or Lyot-Ohman filters and include polarizers and electro-optical crystals, preferably liquid crystals.

Photographic color copying apparatus and exposure control process

A device for measuring an electric field comprises three optical fiber sensors, which each have a piezoelectric sensor element, as well as an interferometer for generating a sensor signal. The optical fiber sensors have piezoelectric sensor elements that exclusively detect with the aid of the inverse piezoelectric effect a predetermined directional component, assigned in each case, of the electric field. The directional components of the different sensor elements are each aligned perpendicular to one another. An evaluation circuit determines the absolute value and direction of the electric field from the sensor signals generated. The sensor elements are preferably formed by a single piezoelectric body, on whose faces the sensor fibers are fixed.

Device for measuring an electric field

An alignment layer for a liquid crystal display consists at least substantially of a polyphenylene polymer wherein at least 80% of the said polyphenylene polymer is composed of aromatic phenylene rings. The alignment layer is capable of providing a homogeneous alignment of liquid crystal molecules disposed adjacent thereto with a high tilt bias angle.

Liquid crystal devices

A fibre-optic sensor for measuring a particular directional component of an electric field comprises a piezoelectric body (4) and a glass fiber (5a) which is rigidly connected to the piezoelectric body (4) in a given length section. A crystal class and a crystallographic orientation of the piezoelectric body (4) is selected in such a manner that only the directional component which is parallel to a given body axis (h) of the piezoelectric body (4) causes a change in a length of the glass fiber (a) by means of an inverse piezoelectric effect. The change in length is measured interferometrically. In a preferred embodiment, the piezoelectric body has the shape of a disk, of a plate or of a hollow cylinder.

Fiber-optic electric field sensor with piezoelectric body sensor

An optoelectronic displacement sensor for the absolute measurement of displacement in the sub-micrometer range is described, which is constructed, according to an exemplary embodiment, with a light-emitting diode (L) as light source and two photodiodes (D1, D2), which are arranged in a difference circuit and which are opposite to one another, as radiation sensors. The sensing of displacement takes place by means of a diaphragm (2), which is displaceable between light source and radiation sensors and which influences the illumination received by of the photodiodes (D1, D2). For the homogenization of the illumination, special means are provided, which, according to an exemplary embodiment, consist of a correction filter (6) disposed in the beam path.

Optoelectronic displacement sensor with correction filter

A process and apparatus for the production of an orientation layer on a plane surface of a plate, and a liquid crystal substrate plate produced thereby. By the process of evaporation from a source, orientation layers are deposited on the plane surfaces of a plurality of liquid crystal substrate plates used for application in liquid crystal displays. To obtain a uniform orientation of the optic axis of the liquid crystal with regard to the azimuthal alignment by means of the preferred direction caused by the orientation layer on the surface, the plates are moved in a direction crosswise to the evaporation direction during the evaporation process. The field of the particle stream emanating from the source is limited by an aperture in an aperture screen which is introduced between the source and the plates. The plates pass completely through the particle stream during the course of the evaporation operation. The finished plates include an approximately 5 nm thick orientation layer. In the apparatus, the plates are held in a wagon which is moved along rails by means of a toothed rack and a toothed pinion.

Process and apparatus for the production of an orientation layer on a

A novel light scattering reflector and methods of making and using it are disclosed. The reflector, which can advantageously be used in conjunction with liquid crystal displays, includes a layer carrier formed of glass or rigid PVC foil. The layer carrier is roughened by sandblasting, impressing with a grooved die, or by other techniques to provide an irregular surface. A reflective metal coating is subsequently evaporated onto the roughened surface to complete the reflector structure. Auxiliary materials may also be coated onto the layer carrier to improve the characteristics of the device.

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Wettingen, Switzerland

Jurgen Nehring