Rockwell International Corporation

Steve Beccue

Mohsen Khoshnevisan

Jeffrey S Schoenwald

Bruce G Kolloff

Jonathan P Rode

Raymond J Smith

An interferometrically readable optical encoder for sensing linear position includes an optical medium movable in a linear direction and having a data storage layer, a plurality of uniformly sized sectors being defined in the layer. A linear absolute track is defined in the layer parallel to the linear direction and a plurality of absolute marks is formed in the layer in sequence along the absolute track within each sector, each such absolute mark being detectable by interferometric reflection of coherent light as representative of a binary 1 or a binary 0 and each such plurality of absolute marks defining a binary word. A linear incremental track is defined in the layer parallel to the linear direction with a series of incremental marks formed in the layer and evenly spaced along the first incremental track, each such incremental mark being detectable by interferometric reflection of coherent light. The binary word in a sector is read to identify the position of that sector in the linear direction and indicate the approximate position of the medium. The incremental marks refine the approximate position indication to provide a more precise position of the medium.

High resolution optical hybrid digital-analog linear position encoder

An optical encoder for sensing angular position includes a rotatable optical medium having a major surface and an axis of rotation perpendicular to the surface, with a plurality of uniformly sized angular sectors defined on the surface. An annular absolute track is defined on the surface concentric with the axis, a plurality of digital bits being formed on the surface in sequence along the absolute track within each sector. Each such bit is optically readable as a binary 1 or a binary 0, with each plurality of bits defining a binary word. A first series of optically detectable incremental marks are evenly spaced around a first incremental track on the surface. The binary word in a sector is optically read to identify the angular position of that sector and indicate the approximate angular position of the medium, while the first series of incremental marks can be optically detected to refine the approximate angular position indication. A source of light illuminates the surface along a fixed radius from the axis, while a digital track detector senses the illumination reflected from the absolute bits and a first incremental track detector senses the illumination reflected from the incremental marks. Signal processing and decoding means convert the output of the absolute track detector into a binary word and interpolate the precise angular position of the medium from the output of the first incremental track detector. An input absolute track optical fiber is connected between a absolute track optical coupler and proximate the surface of the medium, while a first input incremental track optical fiber is connected between a first incremental track optical coupler and proximate the surface. Output absolute track and first incremental track optical fibers are connected between the couplers and the track detectors for conveying reflected light from the tracks to the detectors.

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Oxnard, CA, United States of America

Steve Beccue