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Optical Engineering

Incoherent Optical Quality Control Of Radiographic Grids
Author(s): Giovanni Crosta
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Paper Abstract

The radiographic grid is an array of high atomic number blades interleaved with relatively transparent ones. The radiograph of a grid is a grating having a square wave transmittance function. If two such radiographs are superposed in a convenient way and looked at on a film viewer, moire fringes appear. From visual inspection of the fringes several structural defects in the grid show up. Some pictures explain how to enhance line defects, frequency, and pulse width modulation defects, all of them being related to uneven thickness of the blades which form the grid. Other manufacturing defects, which do not affect the periodical structure and must therefore be detected by other test methods, are also discussed.

Paper Details

Date Published: 1 August 1981
PDF: 6 pages
Opt. Eng. 20(4) 204562 doi: 10.1117/12.7972762
Published in: Optical Engineering Volume 20, Issue 4
Show Author Affiliations
Giovanni Crosta, Consultant (Italy)

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