Carbon fiber lay-ups are tested for porosity using optical instruments.
The sample coupon in the image (bottom right) is large enough to be polished without being mounted in epoxy. If the samples are smaller, they are sectioned and mounted in epoxy pucks (bottom left) then polished before testing.
Your samples will be cross sectioned and progressively polished. The finishing polish uses 3 micron diamond paste to achieve an exceptionally smooth surface capable of being viewed under the electron microscope without surface imperfections to mar results.
Once prepped, they are analyzed and measured for porosity vs. the total surface area.
Samples are most often analyzed using BAC5980 optical method, or to your specifications.
100x image of a carbon fiber cross-section exhibiting no porosity
100x image of a carbon fiber cross-section exhibiting high porosity