Sophomoric MIT student laser work

As undergrads in the late fall of 1969, John and I were both taking an optics course, six point something or other. It required a lab project. Perhaps primed by Star Trek and Mission Impossible, we ambitiously decided to build a long-distance laser communicator.

There was clear line-of-sight from the top of MIT Building 24, looking over the shoulder of the Great Dome, to my 5th-floor apartment on the other side of the Charles, on Mass Ave near Beacon St. At just over a kilometer, that seemed a long enough distance to prove the point. A safely low-milliwatt helium-neon laser (the red kind) would carry our signals. A high-voltage transistor would modulate the laser’s couple-hundred volt input power. (I think we asked first, before we tore into the laser to re-engineer our transistor into the circuit.) Continue reading “Sophomoric MIT student laser work”