Quote from: Sybil on October 27, 2013, 03:54:17 PM
I also have never heard anything about how deeply rooted the hair is, only about growth phase and hair color vs. skin color, but I couldn't say it is not an issue for sure -- I'd like to know more about that, too.
Wavelength/Spectrum
• The measure of distance between repetitions of light, calculated in nanometers (nm). Higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths.
• IPL devices emit a broad spectrum of light, then filter out undesirable wavelengths (such as ultraviolet rays). Higher wavelengths allow for deeper penetration of light and greater absorption by melanin in hair. For example, in the image to the right, you can see that wavelengths above 650 nm penetrate deeper into the skin, where it can effectively target the hair follicle (where the majority of melanin resides).
• Lower wavelengths between 400-550 nm penetrate less than 2 mm below the skin surface, missing much of the melanin in the hair bulb and unnecessarily heating the upper layers of skin (dermis).
• Most professional hair removal devices have higher wavelength cutoffs.
For comparison:
Argon: 488 nm (Turquoise/Cyan) or 514.5 nm (Green) (no longer used for hair removal)
Ruby laser: 694.3 nm (Deep Red) (no longer used for hair removal; only safe for patients with very pale skin)
Alexandrite: 755 nm (Near-Infrared) (most effective on pale skin and not safe on darker skin at effective settings)
Pulsed diode array: 810 nm (Near-Infrared) (for pale to medium type skin)
Nd:YAG laser: 1064 nm (Near-Infrared) (made for treating darker skin types, though effective on all skin types)
IPL or Intense pulsed light: 810 nm (Not a laser but used for hair removal) (for pale to medium type skin)
You're welcome.