Most in the esthetic and medical esthetic fields are familiar with the terms intense pulsed light (IPL), light-emitting diode (LED) and LASER (light amplification by stimulated emission of radiation). Technically, a laser is a source of high-intensity optical, infrared or UV light. The photons involved in the laser-emission process all have the same energy and phase so that the laser beam is monochromatic and coherent, allowing it to be brought to a fine focus.
Coherent vs. noncoherent light sources
A laser beam is different from IPL and LED because it is coherent, simply meaning that the beam has the ability to remain focused over a distance. IPL and LED are noncoherent, meaning the light scatters with shorter depth of penetration, while laser is coherent, thus providing a targeted treatment. With coherence, the scattering of light decreases, allowing the light to strike the target at perpendicular angles, increasing its absorption and transmission to deeper tissues.
Cold laser therapy
Cold laser therapy—also known as low-level light therapy—supplies energy to the body in the form of nonthermal light photons, hence the term “cold laser.” Cold lasers use light waves in the near-infrared ranges that penetrate the deepest in the visible spectrum.