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Run the Automated Map
Once all of the previous steps have been carried out it is now
time to collect the crystallographic orientations. Once the
run is started the software will collect an EBSD pattern at
each pixel, detect the bands in the EBSD pattern, calculate
the best fit to the band positions using the candidate crystal
structures, calculate the unit cell orientation, save the infor-
mation and move to the next pixel and repeat this series.
Even though modern EBSD systems are capable of running
100–1000 patterns each second, larger maps may consist of
more than a million pixels and thus require hours or days to
collect. A map of 2000 × 1000 pixels taken at a setting that
allows 100 patterns to be collected and analyzed each second
will require nearly 6 h to complete. Faster acquisition rates
are available but at the expense of orientation accuracy or
noise. Quite often it is most efficient to run these longer
acquisitions overnight when the SEM is not being utilized
anyway. These long acquisition times put extra emphasis in
the microscope’s environment in order that sample drift due
to temperature changes or other disturbances are minimized.
It is also quite useful to post a note on the operating panel of
the SEM so that the next user does not disturb an ongoing
acquisition or assume that the microscope has been left in a
safe condition with respect to the inserted EBSD cameras.
29.2.6 Display of the Acquired Data
EBSD is somewhat unique in analytical techniques as there
are so many ways to present the collected data in meaningful
ways. Of course, everyone likes to produce beautiful color
maps of microstructures, but in reality it is not just the images
that are important but the crystallographic data that is con-
tained in every point in an image that is important. In order
to get that data, one must begin to use and understand crys-
tallographic representations of the sample that are not simple
images. Although it is beyond the scope of this chapter to
describe every possible way that EBSD data can be displayed
it is important to at least introduce these and how they might
be utilized (Randle and Engler 2000 ).
Quite often, the first map that EBSD practitioners display
is called a band contrast or an image quality map or other
names depending on the particular vendor involved. These
images are most commonly shown as gray-scale images
where the gray level is scaled by some measure of the quality
of the pixel by pixel EBSD pattern. The sharper or more
defined the pattern is the higher the gray level in the image.
These images can be striking representations of the micro-
structure of the sample and can reveal microstructural details
not clearly visible in either light-optical microscope images
or secondary or backscattered electron images in the SEM.
One of the most common ways to display EBSD orienta-
tion data is with orientation maps. More accurately these are
called inverse pole figure maps with respect to a specific
physical direction. In order to understand inverse pole figure
maps it is important to understand what are pole figures and
inverse pole figures and how to interpret them.
Pole figures are used to answer the question, Where does
a particular crystallographic direction or plane fall in space
relative to some arbitrary physical sample direction or plane?
Pole figures have been used for many years and are very com-
mon in the preferred orientation or texture literature. In
many cases a single pole figure does not provide sufficient
information and additional pole figures of other crystallo-
graphic directions are required. A pole figure is simply a ste-
reogram with the axes defined by the external reference
frame. It is common for evaporated or deposited thin films to
have a specific crystallographic direction parallel to the film
growth direction.. Figure 29.17 is a series of pole figures
from an evaporated Au thin film. In this example we show the
[111] and the [110] pole figures. For the <111 > pole figure we
note that there is a large number of poles plotted in the center
of the pole figure. This shows that many of the pixels in the
data set have the <111 > direction aligned with the sample
normal. There are additional rings also in the <111 > pole fig-
ure. These are a result of there being more than one <111 > type
direction in a cubic crystal (in fact there are actually four of
these present). In the <110 > pole figure we see that there is a
number of poles in the center of the pole figure indicating
that there are a number of measured pixels with <110 > direc-
tions parallel to the sample normal direction.
Inverse pole figures are used to answer the question,
What crystallographic poles or planes are preferentially par-
allel or perpendicular to a specific sample direction? We usu-
ally again display these with respect to the physical axes of
the microscope or the sample as described for the pole fig-
ures. For inverse pole figures we plot all of the directions that
are pointing in a specific direction of the sample. Inverse pole
figures are extremely useful for samples where there are spe-
cific axes of the sample that have a preferred crystallographic
direction.. Figure 29.18 is an example of inverse pole figures
plotted for the same Au-thin film shown in. Fig. 29.17. It is
often helpful to show all three orthogonal directions so that
the preferred texture can be visualized. Note that the inverse
pole figures of. Fig. 29.18 show exactly the same informa-
tion that is shown in. Fig. 29.17. It is sometimes helpful to
first plot the inverse pole figures as they will give an indica-
tion of the samples texture without plotting pole figures of
many different directions. The Z or surface normal direction
of the inverse pole figures of. Fig. 29.18 is the one that car-
ries the most information about the sample. Here we see the
high density of pixel orientations that are clustered around
the <111 > and less so around the <110 > directions.
Once we are familiar with the concepts of pole figures
and inverse pole figures, we can then go ahead and under-
stand inverse pole figure maps which are one of the more
common ways that EBSD orientation data is shown. An
inverse pole figure map extends the idea of an inverse pole29.2 · Electron Backscatter Diffraction in the Scanning Electron Microscope