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SD-OCT Base Unit Chapter 4: System Operation
Page 34 MTN012389-D02
Rough Surfaces
Rough interfaces between two layers with different refractive indices will lead to reduced sensitivity. The reason
is that the sample light is scattered at the interface and directed into various directions. Here, it is often helpful
to use an immersion gel and a flat surface (e.g. a glass slide) to reduce scattering.
Thorlabs offers sample z-spacers that provide a glass plate at a fixed distance to reduce scattering effects and
to keep the sample in focus, please contact Thorlabs for more information.
Figure 38 Plastic with Matte Surface, Partially Covered with Clear Adhesive Tape
Figure 38 shows a B-scan of a plastic substrate with a matte surface. The right part of the surface was
covered with a strip of adhesive tape to make the rough surface smoother. Due to this smooth surface, the
OCT image is much more consistent and the contrast in deeper layers is much better compared to the plain
matte surface that is shown on the left. This is the same effect that can be seen when looking through a
transparent material with a matte surface. As an example, frosted glass becomes more transparent with
water.
4.4. Shutting Down the System
The following steps should be followed when shutting down the system:
1) Save any important data.
2) Close the Thorlabs software.
3) Shut down the PC.
4) Turn the power switch on the base unit to “
0
”.