structured plates and complex structured aluminium materials are
presented along with a quantitative discussion on defect detection
and sizing. Then, the effect of X-ray source energy and slit width of
the backscatter camera on the quality of the X-ray backscatter
image is presented. Finally, some important applications of the
proposed technique in aerospace industries are discussed.
2. Development of an X-ray backscatter technique for non-
destructive testing of materials
The X-ray backscatter technique presented in this work uses an
un-collimated X-ray radiation to irradiate the whole object being
inspected. It uses a novel combination of a unique twisted-slit
collimator and a digital detector array (DDA) to image backscat-
tered radiation. Fig. 2 shows the schematic of the X-ray backscatter
technique for non-destructive imaging of aerospace materials. In
the following, a detailed description on the new twisted slit
collimator and construction of the X-ray backscatter camera are
discussed.
2.1. Novel twisted slit collimator
Fig. 3(a) shows the schematic of the new twisted slit colli-
mator. The inside of the slit is lined with ruled surfaces
consequently the linear passage of the backscatter radiation
through the slit is possible only through a hole-shaped gap in
any through thickness direction [9,22]. The schematic of the
constructed twisted slit collimator with dimension 50 mm
(length) Â 50 mm (height) is shown in Fig. 3(b). Here, the slit
is made from tungsten with a wall thickness of 50 mm. On the
front side, the slit is inclined into one direction and on the