Interferometric method and apparatus for sensing surface deformation of a workpiece subjected to acoustic energy
AssigneeKrautkramer-Branson, Incorporated
InventorWalter Kaule
Life of this patent
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Abstract
In contact-free testing a workpiece by ultrasonic energy an interferometric method and apparatus is used to sense acoustic energy by determining the deformation of a workpiece surface while such workpiece is undergoing acoustic exploration. The surface of the workpiece is illuminated by a laser beam which is reflected thereat and reaches an optical beam splitter to produce a measuring beam portion and a reference beam portion. The measuring beam portion after reflection at a mirror is transmitted to photoelectric means, while the reference beam portion is time delayed via an optical delay path and then brought to interfere with the measuring beam portion at the photoelectric means.
Claims18
The method of sensing by optical interference the deformation of a workpiece surface resulting from transmitting acoustic energy into the workpiece comprising:
- applying to a workpiece acoustic wave energy for causing surface deformation on such workpiece;
- transmitting a monochromatic beam of light upon the surface of the workpiece for sensing such deformation;
- splitting said beam after reflection at said workpiece surface into a measuring beam portion and a reference beam portion;
- transmitting said measuring beam portion to photoelectric sensing means, and
- transmitting said reference beam portion over a delay path and thereafter bringing said reference beam to coincidence with said measuring beam portion at said photoelectric means.
An apparatus for sensing by optical interference the deformation of a workpiece surface resulting from acoustic energy applied to such workpiece comprising in combination:
- means coupled for applying to a workpiece acoustic wave energy for causing surface deformation on such workpiece;
- a source of laser beam disposed for directing its beam upon a surface portion of the workpiece for sensing such deformation;
- an optical beam splitter;
- an optical delay path and photoelectric sensing means so disposed that said laser beam responsive to being directed upon the surface portion of the workpiece and being reflected thereat reaches said beam splitter and a first measuring beam portion leaving said splitter is incident upon said sensing means, while a second beam portion leaving said splitter as a reference beam is transmitted over said delay path toward said sensing means for concidence with said first beam portion.
Dependencies are inferred from the claim text.