40Hr Laser Hair Removal Apprentice in Training Practice Test

Wavelengths describe the spacing between peaks of a light wave, and for visible and near-infrared light used in lasers, that distance is extremely small. Nanometers are used because a nanometer is one billionth of a meter, which matches the scale of typical laser wavelengths (about 400–1100 nm). Kilometers, inches, and feet are far too large to describe a light wave. So the correct unit is nanometers, which is why laser wavelengths for hair removal are specified in nanometers (e.g., 755 nm, 810 nm, 1064 nm).