Comment by Zanfa
16 hours ago
Dan Gelbart's lecture on sensors[0] explains another fascinating method in detail using RF as well as the optical scanning method mentioned in the original video. The full lecture is worth a watch, but the timestamp is where the RF method explanation starts.
That Dan Gelbart lecture where he also explains how retroreflection[0] is used to detect remote viewing, was it anything with a lens or even human eye is really good.
[0] straight link to where he explains retroflection https://youtu.be/0MtRxX0crjU?t=3019
Also many other videos where he explains how to solve hard problems are really good too.
e: There seems to be commercial product using retroreflection advertised Youtube
https://www.youtube.com/watch?v=NaXSRpTeMbU