- Ruby laser
A ruby laser is a
solid-state laserthat uses a synthetic rubycrystal as its gain medium. It was the first type of laserinvented, and was first operated by Theodore H. "Ted" Maiman [Maiman, T.H. (1960) "Stimulated Optical Radiation in Ruby". "Nature", 187 4736, pp. 493-494.] at Hughes Research Laboratorieson 1960-05-16[ cite web
title = Laser inventor Maiman dies; tribute to be held on anniversary of first laser
publisher = Laser Focus World
date = 2007-05-09
url = http://www.laserfocusworld.com/display_article/292149/12/none/none/INDUS/Laser-inventor-Maiman-dies;-tribute-to-be-held-on-anniversary-of-first-lase,
accessdate = 2007-05-14 ] .
The ruby laser produces pulses of visible light at a
wavelengthof 694.3 nm, which appears as deep red to human eyes. Typical ruby laser pulse lengths are on the order of a millisecond. These short pulses of red light are visible to the human eye, if the viewer carefully watches the target area where the pulse will fire.
Ruby lasers have declined in use with the discovery of better lasing media. They are still used in a number of applications where short pulses of red light are required. Holographers around the world produce holographic portraits with ruby lasers, in sizes up to a metre squared. The red 694 nm laser light is preferred to the 532 nm green light of frequency-doubled .Fact|date=February 2007 Many
non-destructive testinglabs use ruby lasers to create holograms of large objects such as aircraft tires to look for weaknesses in the lining. Ruby lasers were used extensively in tattoo and hair removal, but are being replaced by alexandrite lasers and s in this application.
The ruby laser is a three level solid state laser. The
active laser medium(laser gain/amplification medium) is a synthetic rubyrod that is energized through optical pumping, typically by a xenon flash lamp. In early examples, the rod's ends had to be polished with great precision, such that the ends of the rod were 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 were silvered: one end completely, the other only partially. The rod with its reflective ends then acts as a Fabry-Pérot etalon(or a Gires-Tournois etalon). Modern lasers often use rods with ends cut and polished at Brewster's angleinstead. This eliminates the reflections from the ends of the rod; external dielectric mirrors then are used to form the optical cavity. Curved mirrors are typically used to relax the alignment tolerances.
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