Alexandrite lasers became available for use in laser hair removal in 1997 when they were cleared by the FDA. Alexandrite lasers produce light beams in the red spectrum of visible light.
Their wavelength is 755 nanometers which is very effective but only safe on light skin. Generally, alexandrite lasers are considered long pulsed and because of this produce greater depth penetration. Five different types of the alexandrite laser are available. These include the Apogee, GentleLase, Epicare, Epitouch Alex, and Ultrawave II-III.
The FDA also cleared diode lasers for use in 1997 as an effective method of permanent hair reduction. Diode lasers produce a wavelength of 800 nanometers with pulse widths of 5-400 milliseconds. This type of laser has proved successful in the treatment of ingrown eyelashes and works very well on dark hair. The Light SheerXC is a diode laser that is extremely powerful. Other diode lasers include EpiStar, Apex-800, Iridex, and Mediostar.
Ruby lasers were also cleared by the FDA for laser hair removal in 1997, however, they did not prove as effective. Clinical research showed that the laser damage did not extend far enough down into the hair shafts to result in permanent laser hair removal. Originally there were five types of ruby lasers, of which only two are still available for commercial use. A Ruby lasers operate on a shorter wavelength system of only 694 nanometers.
NeoDymium Yttrium Aluminum Garnets have a longer wavelength which makes them more effective for longer term, and according to some people, even permanent laser hair removal. There are two types of Nd:YAGs lasers. These are the Q switched and the long pulse. All Nd:YAGs produce a wavelength of 1064 nanometers. The Q, switched NeoDymium Yttrium Aluminum Garnets has a very short pulse of about one nanosecond. Long pulse NeoDymium Yttrium Aluminum Garnets have a pulse of about a millisecond and can be used on all skin types.
The pulse duration, or pulse width, of lasers used for hair removal is the timing of the light energy. It is usually measured in milliseconds. Most lasers used for hair removal have a maximum pulse duration in the 20 to 40 millisecond range. Longer pulse widths are generally considered more effective and produce fewer side effects.
Each type of laser produces a specific spot size which is measured in millimeters. The spot size is the size, or width, of the beam of light at the laser sends out. A spot size of seven to 10 mm is considered acceptable for laser hair removal.
Most lasers have three main parts, an energy source, and active medium, and an optical cavity, also known as a resonator. The energy source is a device that supplies energy to the active medium. Laser hair removal devices use electricity as their energy source. The element of the active medium contains atoms that can both absorb and store the energy. The optical cavity is the part of the laser that contains the active medium. Lasers are defined by the elements they use.