NDTnet 1998 Aug, Vol.3 No.8

Abstract

This research examines the feasibility of a technique based upon the CT principle. A microfocus source and a 22 cm image intensifier are being used while the object is being rotated on a CNC turntable. The back-projection process is performed on 180 angles, with an I degree steps. Due to the size of the microfocus tube (about 8 microns), an enlarged image (up to x 400) can be obtained by changing the geometry of the exposure or optical settings.

The data to be processed arrives from the whole surface of the image intensifier, instead of one line of detectors as in commercial CT. The image of each angle is generated by summation of 16 frames using a frame grabber. In this way the SN ratio is considerable improved. Since reconstruction of a very large image still encounters technical difficulty in our system, the image size is 100x100 pixels. A 3D matrix (100x100x100 pixels) is being reconstructed by summation technique and data can be viewed by choosing any layer in any direction in this matrix. A mathematical filter is used to improve the quality of the images before summation and the final summed up image.

The method has been tested on several high contrast items, e.g. a cylinder consisting of 3 different and concentric materials, a cylinder on non-concentric composition, etc.The obtained tomographic images satisfactory fits simulated results.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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