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.
Crosta, G. (1981). Incoherent Optical Quality Control of Radiographic Grids. OPTICAL ENGINEERING, 20(4), 562-567 [10.1117/12.7972762].
Incoherent Optical Quality Control of Radiographic Grids
CROSTA, GIOVANNI FRANCO FILIPPO
1981
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.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
