Also the new generation of mm wave radar devices, which can see through some materials. Here is a good rerun of an Andreas Spiess video covering some recent-ish

Also the new generation of mm wave radar devices, which can see through some materials. Here is a good rerun of an Andreas Spiess video covering some recent-ish sensors: https://www.youtube.com/watch?v=gU-Rrwf1vr0 https://www.youtube.com/watch?v=gU-Rrwf1vr0