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Title: Apparatus for measuring surface movement of an object that is subjected to external vibrations

A system for non-destructively measuring an object and controlling industrial processes in response to the measurement is disclosed in which an impulse laser generates a plurality of sound waves over timed increments in an object. A polarizing interferometer is used to measure surface movement of the object caused by the sound waves and sensed by phase shifts in the signal beam. A photon multiplier senses the phase shift and develops an electrical signal. A signal conditioning arrangement modifies the electrical signals to generate an average signal correlated to the sound waves which in turn is correlated to a physical or metallurgical property of the object, such as temperature, which property may then be used to control the process. External, random vibrations of the workpiece are utilized to develop discernible signals which can be sensed in the interferometer by only one photon multiplier. In addition the interferometer includes an arrangement for optimizing its sensitivity so that movement attributed to various waves can be detected in opaque objects. The interferometer also includes a mechanism for sensing objects with rough surfaces which produce speckle light patterns. Finally the interferometer per se, with the addition of a second photon multiplier is capable of accuratelymore » recording beam length distance differences with only one reading.« less
Inventors:
 [1];  [2];  [3]
  1. (Waban, MA)
  2. (North Reading, MA)
  3. (Newton, MA)
Issue Date:
OSTI Identifier:
870912
Assignee:
Textron Defense Systems, Division of Avco Corporation (Wilmington, MA) IDO
Patent Number(s):
US 5623307
Contract Number:
FC07-89ID12830
Research Org:
Surface Combustion, Inc. (Maumee, OH)
Country of Publication:
United States
Language:
English
Subject:
apparatus; measuring; surface; movement; subjected; external; vibrations; non-destructively; controlling; industrial; processes; response; measurement; disclosed; impulse; laser; generates; plurality; sound; waves; timed; increments; polarizing; interferometer; measure; caused; sensed; phase; shifts; signal; beam; photon; multiplier; senses; shift; develops; electrical; conditioning; arrangement; modifies; signals; generate; average; correlated; physical; metallurgical; property; temperature; control; process; random; workpiece; utilized; discernible; addition; optimizing; sensitivity; attributed; various; detected; opaque; mechanism; sensing; surfaces; produce; speckle; light; patterns; finally; capable; accurately; recording; length; distance; differences; reading; random vibrations; recording beam; movement attributed; signal correlated; various waves; timed increments; speckle light; average signal; produce speckle; accurately recording; beam length; arrangement modifies; non-destructively measuring; metallurgical property; measure surface; multiplier senses; laser generates; light pattern; impulse laser; controlling industrial; conditioning arrangement; length distance; discernible signals; distance differences; industrial processes; photon multiplier; phase shift; electrical signals; sound waves; electrical signal; signal beam; industrial process; polarizing interferometer; phase shifts; surface movement; measuring surface; signal conditioning; light patterns; external vibrations; pulse laser; sound wave; /356/73/

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