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The applications of this information to materials
science were discussed earlier in this chapter. The
information in the discs includes 1) HOLZ (High Order Laue
Zone) lines, for lattice parameter measurements and for
pattern symmetry determinations, 2) Pendellosung Fringes,
used in making foil thickness determinations, 3) the
shadow image, used for tilting the sample and placing the
beam, and 4) dynamical features (absences and excesses)
that reveal detailed information about the crystal space
group for crystal symmetry and space group
determinations. Since HOLZ lines were used extensively in
this study, they are described in more detail below.
4.1.2 HOLZ Lines (High Order Laue Zone Lines)
A HOLZ line is a locus of diffracted beams. It is
the result of elastic scattering from Laue zones beyond
the zero order zone. HOLZ lines are analogous to Kikuchi
lines in two respects. First, they are a Bragg
diffraction phenomenon, and second, they result in lines
rather than diffraction spots. Like Kikuchi lines, the
spacing between the HOLZ lines in the diffracting disc and
the transmitted disc represents the spacing of the planes
that are responsible for Bragg diffraction in the HOLZ.
It is only necessary to index the discs that are
diffracting in the HOLZ to determine which lines in the
ZOLZ (Zero Order Laue Zone) correspond to these
diffracting discs. Any HOLZ line in the ZOLZ will