The technology
How an Nd:YAG laser works and what 1064 nm does
Nd:YAG stands for neodymium-doped yttrium aluminum garnet, the crystal that produces 1064 nm light when pumped. The wavelength sits in the near infrared, where melanin and hemoglobin absorb it only weakly and water hardly at all, so it penetrates deeper than any other common aesthetic wavelength and passes through the epidermis with little heating. That single property explains all of its uses.
Pulse modes
- Q-switched (nanosecond pulses): the pulse is stored and released in a few billionths of a second, which fractures tattoo ink and pigment particles. 1064 nm for black and dark inks and for melasma and pigment toning; 532 nm (the same laser frequency-doubled with a KTP crystal) for red ink and superficial pigmented lesions. A carbon peel uses the Q-switched mode over a carbon lotion. The Shape Tactics NDPlus and Mini ND YAG are this type.
- Long-pulse (millisecond pulses): the energy is delivered over milliseconds to heat a target gently: hair follicles on darker skin, and vessels for spider veins and vascular lesions. The 1064 nm source in the Alexpulse EL200B is used this way for hair removal and vascular work.
Why darker skin
Because melanin absorbs 1064 nm weakly, the epidermis of Fitzpatrick IV to VI skin takes far less energy than it would at 755 or 808 nm, which makes long-pulse Nd:YAG the standard hair removal wavelength for darker and tanned skin, and Q-switched 1064 nm the standard pigment wavelength when heat on the surface is the concern.
