Focused Line Source Linear Array Holography Using a Three Dimensional Computer Reconstruction System
This paper describes a unique holographic scanning configuration and computer reconstruction technique for the inspection of thick-walled nuclear pressure vessels.
The holographic imaging system consists of a focused line source and a 120 element receiver array operating at 2.31 MHz. The source and receive arrays are aligned parallel with each other, simulating simultaneous source-receiver scanning in the mechanical scanned direction. The holographic information is obtained by mechanically scanning perpendicular to the arrays and electronically multiplexing the receiver array. This hybrid scanning configuration produces directional resolution and astigmatism in the holographic reconstruction.
The computer reconstruction system is capable of generating near-real time holographic images via an array processor and FFT operation. The system has the unique ability of integrating up to ten images into one three dimensional composite image with the options of tilt and rotation.1
A computer spatial frequency filtering program provides the unique capabilities of image enhancement and object characterization.
Experimental imaging results are presented of various objects and defects in thick-walled metals graphically illustrating the capabilities of the holographic imaging system.
KeywordsReceiver Array Resolution Test Holographic Image Digital Reconstruction Computer Reconstruction
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