Polarizing optical interferometer having a dual use optical element

Patent · 01 January 1995

OSTI ID:869821

Kotidis, Petros A ^[1]; Woodroffe, Jaime A ^[2]; Rostler, Peter S ^[3]

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1. Waban, MA
2. North Reading, MA
3. Newton, MA

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 accurately recording beam length distance differences with only one reading.

• Research Organization: Surface Combustion, Inc. (Maumee, OH)
• DOE Contract Number: FC07-89ID12830
• Assignee: Textron Defense Systems, Div. of Avco Corporation (Wilmington, MA)
• Patent Number(s): US 5404224
• OSTI ID: 869821
• Country of Publication: United States
• Language: English

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/356/73/
accurately
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arrangement
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metallurgical
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non-destructively
non-destructively measuring
opaque
optical
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optical interferometer
optimizing
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phase
phase shift
phase shifts
photon
photon multiplier
physical
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polarizing
polarizing interferometer
process
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produce
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pulse laser
random
random vibrations
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signal beam
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sound
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speckle
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surface
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timed
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various
various waves
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workpiece