Method and apparatus for the remote nondestructive evaluation of an object using shearography image scale calibration
OwnerJohn W. Newmaninventor
Life of this patent
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Abstract
A method and apparatus for the remote nondestructive evaluation of an object such as a wind turbine blade involves applying mechanical and/or thermal stress to the object and then scanning the object using long-range thermographic and/or laser interferometric imaging. The laser interferometric imaging is preferably performed by a long range shearography camera capable of imaging deformation derivatives at long distances coupled with a blade stressing mechanism incorporating either thermal or internal blade pressurization for the purpose of detecting remotely and at high speed, changes in the structural integrity of an installed wind turbine blade.
Claims24
A method of calibrating a shearography image, comprising:
- projecting two beams of structured light onto an object to form two dots having a known distance of separation;
- imaging the two dots with a shearography system;
- and
- calibrating the shearography system using the known distance of separation;
- wherein the step of calibrating the shearography system using the known distance of separation comprises determining a shearography image scale in pixels per unit length.
A method of performing a shearographic inspection of an object, comprising steps of:
- projecting two beams of structured light onto an object to form two dots having a known distance of separation;
- imaging the two dots with a shearography system;
- calibrating the shearography system using the known distance of separation;
- and
- using the shearography system to perform inspection of at least a portion of the object;
- wherein the step of calibrating the shearography system using the known distance of separation comprises determining a shearography image scale in pixels per unit length.
Dependencies are inferred from the claim text.