Tsi, Inc.

Sperry Rand Corporation

Leslie M Jenson

Amir A Naqwi

Gerald F Sauter

David L Fleming

An interferometric system for measuring cross-sectional dimensions of glass fibers and other elongate objects includes: a transmitting optics module for generating two laser beams, and causing the laser beams to intersect and interfere with one another over a measuring volume; several photodetectors to collect the light scattered by the glass fiber positioned in the interference region; and signal processing circuitry to deduce the fiber diameter using phase shifts between the signal pairs and fiber velocity using the frequency of the signals. The system further offers: elimination of the 360.degree. limitation on the product of sensitivity (degrees per micron) and range (microns), accompanied by an increase in accuracy using three or more detectors; uniform sensitivity over a large measuring volume, using fringe flare to compensate for changes in the effective angular separation of the detectors, due to fiber displacement within the measuring volume; and insensitivity to fiber tilt using large-area detectors for receiving the light scattered by the fiber.

Device for interferometric measurements with compensation for tilt and

A system for measuring cross sectional diameters of optical fibers and other elongate cylindrical objects includes a transmitting optics module for generating two collimated laser beams, and causing the beams to intersect and interfere with one another over a measurement region. The optical fiber under inspection is caused to intersect the measurement region with its longitudinal axis perpendicular to a plane defined by the laser beams. Several photodetectors collect light scattered by the optical fiber, and generate signals indicating fiber diameter based on phase differences in the scattered light received by the detectors. The system can determine fiber refractive index by using three detectors to obtain two phase shifts. Differences in Doppler frequencies also are sensed by the detectors, for determining transverse velocity components.

Interferometric device for determining sizes and properties of

A system for measuring cross sectional diameters of optical fibers and other elongate cylindrical objects includes a transmitting optics module for generating two collimated laser beams, and causing the beams to intersect and interfere with one another over a measurement region. The optical fiber under inspection is caused to intersect the measurement region with its longitudinal axis perpendicular to a plane defined by the laser beams. Several photodetectors collect light scattered by the optical fiber, and generate signals indicating fiber diameter based on phase differences in the scattered light received by the detectors. Differences in Doppler frequencies also are sensed by the detectors, for determining transverse velocity components.

Interferometric cylinder sizing and velocimetry device

A method and apparatus for automatically detecting a coherent frequency burst is disclosed. The apparatus 10 determines the approximate frequency and duration of the burst. The apparatus 10 operates utilizing principles of autocorrelation to reject random noise and maximize the efficiency of a down stream data signal processor. The apparatus 10 includes delay means 30 which accepts a digitized signal from a device, such as a photodetector in an LDV, and generates a plurality of delayed signals. The delayed signals are then multiplied by the original signals by multiplier means 40. The multiplied signals are provided to averaging circuits 50. The averaged signals are then compared to a reference level by comparators 60, the output of which is provided to priority encoder 70. Priority encoder 70 prioritizes the signals received from comparators 60 and determines the length of the burst.

Coherent frequency burst detector apparatus and method

A Doppler velocimeter having laser generating crossing light beams provides a crossing and focus area forming a measuring volume having regions of high and low light intensity. Solid or liquid particles moving through the measuring volume scatter light which is sensed and converted into a signal having a frequency. A signal processor measures the frequency by detecting and tracking an individual zero crossing of a particle through the measuring volume to provide real time information about the coherent component of the signal. This information is useable to determine the velocity of the particle moving through the measuring volume.

Apparatus and method for measuring frequency of coherent component of a

A method of and an apparatus for determining the best match, i.e., minimum Hamming distance, between a search word and a plurality of file words is disclosed. The method involves simultaneously comparing the search word to a file word and to a match word. If the comparison indicates that the file word is a better match than the match word, the file word becomes the match word and the next file word is compared to the new match word. The operation continues until all the file words have been operated upon such that the last match word becomes the best match word.

Growing community of inventors

Vadnais Heights, MN, United States of America

Leslie M Jenson