The magnetic floppy disk is sometimes used as an (infrared) light filter as shown on some pictures below. That led me to think about the actual magnetic disk and if inconsistencies or damaged could be detected using visual inspection (for example a good backlight and high definition camera). If for example a floppy disk was placed on top of a bright light and visually scanned or inspected would it be possible to find (physical) damage or predict for example bad sectors or damage to the floppy?
Also would using a specific kind of light from the visible spectrum increase or decrease those chances? I think IR (non-visible) would be blocked on the disk material and UV (also non-visible) would be damaging the magnetic disk as discussed here: What is the effect of direct exposure of the magnetic disk of a floppy to ultraviolet (UV) light?.