Space Technology

By: Sergey Orlov, PhD
See also http://hairremovalfacts.googlepages.com - All about Hair Removal.

In addition to lasers, some light-based epilators use a xenon flash lamp which emits full-spectrum intense pulsed light (IPL) . Treatment with this device is sometimes popularly referred to as laser hair removal, though the device is not a laser per se.

Mechanism of action

The primary principle behind laser hair removal is selective photothermolysis. Lasers can cause localized damage by selectively heating dark target matter in the area that causes hair growth while not heating the rest of the skin. Light is absorbed by dark objects, so laser energy can be absorbed by dark material in the skin (but with much more speed and intensity). This dark target matter, or chromophore, can be naturally-occurring or artificially introduced.

Hair removal lasers selectively target one of three chromophores:

Carbon, which is introduced into the hair follicle by rubbing a carbon-based lotion into the skin following waxing (this lotion is an "exogenous chromophore"). When irradiated by a Q-switched Nd:YAG laser, the carbon causes a shock wave capable of mechanically damaging nearby cells. This method has been abandoned since it does not cause permanent loss. (It has been replaced with the long-pulsed Nd:YAG laser which targets endogenous melanin in the follicle.)

Hemoglobin, which occurs naturally in blood (it gives blood its red color). It preferentially absorbs wavelengths from argons, and to a lesser extent from rubies, alexandrites, and diodes. It minimally absorbs the Nd:YAG laser wavelength. Hemoglobin is not a primary target for laser hair removal.

Melanin is considered the primary chromophore for all hair removal lasers currently on the market. Melanin occurs naturally in the skin (it gives skin and hair its color). There are two types of melanin in hair: eumelanin (which gives hair brown or black color) and pheomelanin (which gives hair blonde or red color). Because of the selective absorption of photons of laser light, only black or brown hair can be removed.

Both men and women seek laser hair removal services to have superfluous or unwanted hair removed. Hair removal is commonly done on lip, chin, ear lobe, shoulders, back, underarm, abdomen, buttocks, pubic area, bikini lines, thighs, face, neck, chest, arms, legs, hands, and toes.

Laser is attracted to dark pigment and therefore works best on pale skin and dark coarse hair. The closer you are to this combination (i.e. the lighter the skin and the more coarse and dark the hair), the better the results will generally be after proper treatments.

Hair removal lasers have been in use since 1997 and the Food and Drug Administration approved it for “permanent reduction.” They permanently disable hair follicles, however you have to remember that laser hair removal doesn’t work in the same way on everyone and doesn’t remove 100% of the hair in an area. Generally, this means that you shouldn’t expect to remove every single hair from an area, although you can remove the majority of it (given you are a good candidate with light/medium skin and dark at least somewhat coarse hair). Most people need to follow up with electrolysis treatments for any remaining hairs to achieve complete clearance, if desired, as the remaining hairs become too sparse and fine for laser to target. Some will also need touch-up treatments about once a year, especially on large areas, after the initial set of 6-8 treatments for any new growth your body may develop with age on certain areas. It has also been observed that some people seem to be non-responders – this is not confirmed and reasons are not known, and may in fact be due to lack of skill on the part of many laser operators and/or the type of machine and settings they are using. Keep in mind that it's hard to judge whether someone’s lack of results is due to a potential underlying medical condition that causes continuous growth and makes it seem like laser isn’t working, if the treatment wasn't performed properly, or whether for some people it just doesn't work for currently unknown reasons. In essence, you can’t determine what your personal results would be like unless you try it. Results depend on many variables involved, including the tech's experience, type of laser used, how settings are set, etc. It is recommended to start with one smaller area and see how your hair reacts before committing to an expensive set of treatments on many areas at once.

Electrolysis is an alternative permanent hair removal method that has been used for over 125 years. It involves treating one hair at a time and is a good option for smaller areas (like eyebrows or upper lip) where precision is necessary. It does take considerably more treatments compared to laser to complete a large area, but is an option as well. At this time, it is as the only permanent option for very fine and light-colored hair.

Laser parameters that affect results

Several wavelengths of laser energy have been used for hair removal, from visible light to near-infrared radiation. These lasers are usually defined by the lasing medium used to create the wavelength (measured in nanometers (nm)):

Argon: 488 or 514.5 nm (not used for hair removal anymore)

Ruby: 694 nm (not used for hair removal anymore; not safe on most skin types)

Alexandrite: 755 nm (most effective%