PS Builds a LASER …and so can you
The incredible ruby ray is the hottest scientific discovery of the decade, but practical uses are still scarce. Here’s your chance to join the search
-June, 1960: Dr. T.H. Maiman, of the Hughes Aircraft Co., reports the development of the first successful ruby laser.
â€”November, 1964: Popular Science publishes plans for the first do-it-yourself ruby laser.
By Ronald M. Benrey
IT MAY sound like science fictionâ€” but it’s really science fact: You can build a working ruby laser. It could be the most challengingâ€”and rewardingâ€” home-workshop project that you have ever tackled.
A ruby laser is a source of coherent light. All of the light waves in the pencil-thin, bright-red ruby laser beam are in phaseâ€”or in stepâ€”with each other. This extraordinary property of the laser beamâ€”shared by no other light sourceâ€”has spurred a world-wide search for practical uses.
Ordinary light sourcesâ€”a light bulb, for exampleâ€”generate incoherent light; the light waves are out of phase with each other.
Drop a pebble into a still pond, and the waves ripple out smoothly in all directions. This represents a single light wave from a light source. All light sources produce more than a single wave, however.
They act as if you dropped a handful of pebbles at once: You get a jumbled clutter of waves one on top of another. This clutter of waves is analogous to incoherent light.
Suppose, though, you dropped your handful of pebbles one pebble at a time, each in exactly the same spot in the pond. The waves would continuously radiate from that point. All of the wave crests would be in phase. This is coherent radiation.
A ruby laser generates a coherent light beam by a similar process. Laser is an acronym for Light Amplification by Stimulated Emission of Radiation. Inside the ruby laser rodâ€”heart of the ruby laserâ€”excited atoms are stimulated to emit light waves in phase with each other.