Within an European program we are currently developing an 85 mm, one stage proximity focused image intensifier designed for high energy inspection of corrosion in pipes. The tube is part of a portable robot system using a gamma ray radioactive source such as Iridium-192 (300 to 600 keV) or Cs-137 (662 keV). First tube prototypes have been built with the following characteristics:
- Compact design. The tube itself has an overall thickness of about 4 cm which limits the total thickness of the imaging unit (optics and CCD) to be less than 15cm.
- Thick CsI scintillator input screen: 2 to 4 mm thick which enables an absorption efficiency at 500 keV of up to more than 10% compared to about 1% for a standard Image Intensifier.
- Good resolution due to the needle structure of the Csl layer and absence of distortion thanks to proximity focusing. Limiting resolution of up to 2 Ip/mm allows detection of defects smaller than 0.5 mm.
Furthermore the tube is not sensitive to magnetic fields.
On the basis of the same tube structure, a low energy version including a Beryllium window is under development. This tube will include a specific CsI input screen designed to combine high limiting resolution (resulting to 7 Ip/mm on the tube) and high X-ray absorption at low energy (>90% between 10 and 20 keV). Intermediate solutions based on different Csl thickness are also possible to optimize X-ray absorption for a specific X-ray spectrum.
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:
Publication Contact:
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