Cosmetic hair-removal lasers employ multiple wavelengths of light to acutely target individual hair follicles using a process called selective photothermolysis. Concisely, technicians briefly “pulse” a laser beam for about one millisecond, causing it to emit a high-energy flash of light. This light energy passes safely through the skin, where it interacts with the targeted hair follicle. The follicle responds by absorbing the light, which it immediately converts into heat. This resultant heat energy effectively “disables” the follicle, impairing the hair’s ability to grow.
Because hair removal lasers are only effective during the growth phase, more than one session is generally required for satisfactory results. Scheduling multiple hair removal appointments allows a patient to target as many hair follicles as possible, as not all hairs enter the growth phase at the same time.