Ruby laser

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The ruby laser was the first functional laser invented. Its inventor is Theodore H. "Ted" Maiman, who was, at the time, a Hughes Aircraft employee. On 16 May 1960, his ruby laser produced the first pulse of coherent, visible light made by man.

The ruby laser produces a pulse of visible light with the principal wavelength centered around 694.3 nm, which appears as dark red to human eyes. Typical ruby laser pulse lengths are on the order of a millisecond. The human eye is able to see this duration of pulse at this wavelength, if the viewer carefully watches the target area where the pulse will fire.

Amplification

The ruby laser is a three level laser. The active laser medium (laser gain/amplification medium) is a synthetic ruby rod that is energized through optical pumping. The rod must be prepared to high precision, such that the two ends of the rod are each flat to within a quarter of a wavelength of the output light, and parallel to each other within a few seconds of arc. The finely polished ends of the rod are silvered, one end completely, the other end only partially. The assembly between the reflective surfaces forms a Fabry-Pérot etalon.

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