SD-OCT Base Unit
Chapter 5: Imaging Artifacts
Page 48
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Distortions in the Image
In complex structures, distortions occur in the OCT image which require a close look to be understood.
Figure 61 Different Materials in One Measurement
The loss of imaging depth depends on the amount of material through which the beam passes. As a result the
measured depth in the sample changes throughout the scan.
In the setup shown in Figure 61, one can determine the properties of the materials assuming the underlying
surface to be flat and horizontal in the image. In the OCT image on the right, the physical thicknesses
i
d
, optical
path lengths
i
gi
d
n
, as well as the resulting shifts of underlying structures
i
gi
d
n
)
1
(
can be determined
directly.
The real imaging areas are displayed in the graphic for real sample dimensions on the left.
When the physical structure becomes more complex, the resulting OCT image becomes more difficult to
interpret.
Especially when the surface is not horizontal or curved, effects like shadowing, diffraction on interfaces, and
multiple measured structures may occur in addition to the changes in optical path length.
