On Thu, 14 Apr 2022, John Foust via cctalk wrote:
Magnetic visualizers also discussed here: http://qicreader.blogspot.com/p/track-visualization.html
Thank you. That is what I was looking for.It doesn't imply current existence of anything already coupled with a digital camera, nor particularly suitable for an X/Y positioning system (such as a repurposed plodd^H^Htter) for scanning.
Certainly possible.
