Alexandritelaser

Alexandritelaser is a solid-state laser that uses a chromium-doped alexandrite crystal (Cr:BeAl2O4) as its gain medium. It emits light at 755 nanometers in the near-infrared. Commercial alexandrite systems were introduced in the 1990s and have become common in dermatology, especially for hair removal and treatment of pigmented lesions. Some models also support Q-switched tattoo removal.

The 755 nm wavelength is absorbed by melanin and, to a lesser extent, by hemoglobin, enabling selective photothermolysis of pigmented targets when paired with appropriate pulse duration and cooling. Long-pulsed modes are used for hair removal, while Q-switched modes deliver nanosecond pulses for tattoo removal.

Indications include hair removal for light to olive skin, and treatment of benign pigmented lesions such as lentigines and freckles, as well as tattoo clearance with Q-switched operation.

Risks include epidermal damage and pigmentary changes, particularly in darker skin, as well as transient redness and swelling. Proper cooling, eye protection, and conservative dosing with guidance by a trained clinician reduce adverse effects.

Commercially, the alexandrite laser is marketed by several manufacturers, with Candela's GentleLase among the best known models.