🚀 go-pugleaf

Actually, you can do some modulation without using a variable opaqueness
device in front of the beam.  There was an article in Popular
Electronics about 16 years ago on how to build a modulator-demodulator
for a HeNe laser.  I built one up for the laser our high school had,
but never did get it to work right.  As I recall, it used a "fire-fet"
(vacumn tube) to do the modulation, but I don't remember much else.
You could probably find the back issue in a library (try the Reader's
Guide circa 1969 - 1970) and update it using transistors/ICs.
-- 

	-Bill Randle
	Tektronix, Inc.
	<many machines>!tektronix!tekgen!tekred!billr