Prakt. Met. Sonderband 47 (2015) = 5
h od 3. : Computed X-ray tomography,
ST Cs : nn ; Se ; - "
a X-ray tomography is a three-dimensional imaging, picturing usually the linear absorption coeffi-
cient. It is a well-established procedure in medical diagnostics and gained a growing importance in
industrial applications in the past decades. To record a tomography, it is necessary to take manyj
radiographic images of the object of inspection in different directions which will be reconstructed,
py certain numeric procedures to the 3D data. Several criteria distinguish the individual measure-|
pment routines, some of these are: Time available for the inspection, size of the object, and required,
data resolution. The most usual procedure is the axial tomography where the object is rotated]
around a fixed axis...
Apart from technical details described below the principle stays the same. The object attenuates the
radiation bv A : OL ;
I= oe - | sas
along the oy while u(x) is the linear absorption coefficient at the point x. By recording many of}
these integrals for many rays it is possible to invert this set of equations and to calculate the un-
& Outemost known p(x). This is the well-known Radon theorem. 3
araphy and __ _ _ |
ted that ap- To achieve optimum data, the object should be rotation-symmetric and entirely inside the projec-|
Laue lenses] tions. If this is not the case, typical artefacts occur. The study of flat samples, typically for microe-
layer stack) lectronic and other nanoscale products, is the worst case for tomographic imaging. Therefore, spe-]
: zone platy cial scan geometries have to be applied to improve the quality of the tomographic reconstruction. Al
bn ovis dedicated data recording mode provides the opportunity to investigate such objects [9].
gassed MLL
42 Applications)
X-ray microscopy and tomography are useful across a wide spectrum of sample types. Some appli
cations are: JERE a
Materials Science Will a a
Energy-storage materials (metal/metal oxides for hydrogen storage, metal hydrides, elec
trodes for batteries or fuel cells. ...) oo -
Life Science i _ DE
Biomedical studies (tissues and tissue engineering, bio-engineered materials, ...)
Brain mapping (3D imaging of brain tissue. neural network maps) lll
Geoscience el
Porous sediments (oil and gas extraction)
Microelectronics ill _
Advanced packaging and 3D interconnect structures:
in For many applications, a multi-scale approach, i. e. using imaging techniques with several resolu-}
tion ranges, is necessary fll
