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Title: Method and apparatus for measuring surface movement of a solid 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. 38 figs.« less
Inventors:
; ; ;
Issue Date:
OSTI Identifier:
46317
Assignee:
Textron Defense Systems, Division of Avco Corp., Wilmington, MA (United States) PTO; SCA: 320303; 420500; PA: EDB-95:077392; SN: 95001384522
Patent Number(s):
US 5,410,405/A/
Application Number:
PAN: 8-160,279
Contract Number:
FC07-89ID12830
Resource Relation:
Other Information: PBD: 25 Apr 1995
Research Org:
Surface Combustion Inc
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; 42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES; INDUSTRIAL PLANTS; PROCESS CONTROL; NONDESTRUCTIVE TESTING; MEASURING INSTRUMENTS; DESIGN; LASER RADIATION; PHOTOMULTIPLIERS; MECHANICAL VIBRATIONS

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