465
Scientists Use WiFi to See Through People's Walls
(www.popularmechanics.com)
This is a most excellent place for technology news and articles.
It all comes down to the size of the mirror/lense—the bigger, the better. Up to a point. The biggest problem is air currents and different air densities refracting light and distorting the image. That's what these laser beams are for on photos taken of astronomical observatories—they give reference light spot that can be used to calibrate adaptive optics to current atmospheric conditions reducing distortion.