Laser hair removal machines are lasers tuned to very specific wavelengths, to achieve the process of selective photothermolysis (the absorption of light into hair but not skin tissue) to permanently get rid of unwanted hair. Hair removal machines work best on growing hair follicles though, so a cycle of treatments is usually needed to eradicate all hairs in a given area. Because laser hair treatments are only effective on those hair follicles that are in the anagen or active phase of growth most people need anywhere from six to eight sessions to see long lasting success. Hairs that are in the catagen (regressive) phase or telogen (resting) phase don't respond to laser light. Because about 30% of our hair is in the active stage at any given time, that is why repeated treatments help to ensure that the clinician catches all hair in its active phase eventually. 

Hair removal lasers range in wavelength from 694 nanometers to 1064 nanometers. The longer the wavelength, the more intense the light used to destroy the hair follicle. There are advantages of each level of wavelength, and only a trained professional can evaluate your skin and hair to match it with the correct laser. Alexandrite, diode and Nd:YAG skin lasers have broadened the spectrum of individuals who can benefit from laser hair removal. These newer methods still rely on skin to hair contrast, but are better targeted to different skin tones. If you're interested in permanent laser hair removal, it's a good idea to talk to a professional about the best laser type for your skin and hair tone.

IPL Characteristics
An IPL (intense pulsed light) is not a laser. It is characterized by a wide beam of broad spectrum light and is less specific. It can be used to treat large areas of the body like the back and shoulders. It also treats multiple hairs at a time (up to 100 per second) and works well on any skin type, even ethnic and tanned skin. However, because it is nonspecific, it may take many more treatment sessions than a laser treatment would to achieve the desired goal. IPL treatment is relatively painless and effective. Most people see permanent hair removal, while some others see at least a dramatic thinning of unwanted hair.

IPL treatments can be used on the face, back, chest, bikini area, arms, legs, and pretty much anywhere else you'd like to remove hair. It is a gentle process with few side effects, which makes it increasing popular among men and women alike. The costs are steep though, at up to $800 per session, so you have to take this into account before making your decision about which hair removal method is best for you.