Is there any form of electronic communication, these days, that is absolutely, positively secure?
Yes, indeed! If you have a friend whose home or office is visible from yours, a laser beam would be difficult to intercept. The question is, how would you modulate the beam to carry your secret messages?
Morse code is one answer, but if you don’t want to spend time learning to interpret dots and dashes, you could try voice encoding. Set up a microphone, audio amplifier, and transformer to vary the frequency and intensity of the laser beam, and at the receiving end, a light sensor will feed another audio amplifier, connected with a speaker (see Make: Volume 12, “Simple Laser Communicator,” makezine.com/projects/simple-laser-communicator).
TIME REQUIRED: 3–4 Hours
DIFFICULTY: Easy–Intermediate
COST: $25–$100
MATERIALS
» Red laser…