[zokier]

> My thought is that, if you could develop a sensor capable of sampling magnetic alignment at sub-micrometer resolution it would also generate unbelievable amounts of data that would first need compressing or decoding into AV signals.

Hard disk drive read head sweeping across the tape? Hard disk track widths are well below 1 micron so presumably the potential for high resolution is there?

[nonrandomstring]

Nice idea. I think you'd have a problem with shedding. A HD head is designed to fly/float above a clean platter. Old tape is icky, flaky mess of brown dust and wobbly plastic that would foul up the head PDQ. But rather than scanning maybe you could encapsulate a bunch of old HD densely together in some kind of epoxy/glass to make a high-res tape head?