In a new study (Chen et al. Applications of Long-Pulse Alexandrite Laser in Cosmetic Dermatology: A Review. Clin Cosmet Investigatory Dermatol 2023 Nov 17;16:3349–3357), proved the wavelength and pulse duration of a long-pulse alexandrite laser to remove hair; the long 755nm wavelength can reach the melanin-rich hair follicles by penetrating the epidermis. The melanin in the hair follicle has a stronger selective absorption property when compared to the hemoglobin in the blood vessels surrounding the dermis, which not only ensures the depth of the treatment but also lowers the incidence of redness, swelling, subcutaneous bleeding, and other side effects.
The long-pulse alexandrite laser’s pulse duration is longer than the thermal relaxation time of the epidermis and extremely close to the thermal relaxation period of the hair follicle, providing the best possible results in terms of destroying the hair follicle and sparing the surrounding tissues. The sector of hair removal has seen the most use of the long-pulse alexandrite laser since it was originally introduced in 1997, both for cosmetic and therapeutic objectives.
