I'll throw my 2 cents in here...
A simple way we see media inspection done is by cutting the required square in an index card (rigid paper) and then cover the square hole with shipping tape like a window. The card can be put into the media and patted down onto the card. Remove and gently shake loose media off the card to leave one layer of media in the window.
The card can be placed under a magnification device for inspection. When done, put a piece of shipping tape on the other side of the window to trap the media for archiving purposes.
You can also use a digital microscope to capture the image for record keeping.
