In a SEM it is possible to scan the surface of a DVD (digital video disk) to identify mechanical defects. The following SEM image shows a bit area on the DVD on the left and a zoom into a smaller area that has two scratch shaped defects:

SEM image of a DVD bit area and a zoom showing two scratches

In the following SEM image the two scratches can be visualized and measured in XY, but the depth of the scratches cannot be determined:

SEM image of a DVD bit area and a zoom showing two scratches

The quantitative structure information is visible in the following linescan performed through one of these scratches:

Single linescan across one of the scratches

Only the Dimensional SEM can measure the depth and shape of such defects in DVDs.