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  • Lasers and flashlamps harness the power of light to precisely treat a myriad of cutaneous disorders and conditions.

  • Laser light is monochromatic, coherent, and collimated; whereas, intense pulsed light (IPL) is polychromatic, broadband, and divergent.

  • Upon light’s impact with skin, several tissue interactions occur including reflection, transmission, scattering, and absorption.

  • Laser parameters such as fluence, pulse duration, wavelength, and spot size can be adjusted to safely deliver energy to the skin to achieve desired therapeutic effects.

  • In general, within the visible spectrum longer-wavelength light penetrates more deeply.

  • Laser and light delivered though a larger spot size penetrates more deeply into tissue and is scattered less than with smaller spot sizes.

  • Selective photothermolysis allows lasers and light sources to target specific chromophores in the skin to achieve certain effects while minimizing injury to surrounding structures.

  • Fractional photothermolysis creates evenly distributed zones of microthermal injury in skin to produce columns of injury in the epidermis and dermis, leaving intervening columns of unaltered skin, thereby decreasing healing time and minimizing adverse effects.

  • Knowledge of the potentially hazardous effects of lasers and flashlamps, and implementation of safety measures, are essential to maintain a safe environment for the practitioner, staff, and patient.


Light is a fundamental form of energy that is harnessed in the form of lasers and pulsed light sources that has countless applications in modern medicine. In 1900, Max Planck described that light is released, transferred, and absorbed in specific amounts of energy called quanta.1 In 1917, Einstein published “The Quantum Theory of Radiation” in which he suggested that most atoms exist in a ground-energy state, and upon absorbing energy are converted to higher energy levels. When these excited atoms return to their ground state, they release energy as photons or electromagnetic waves. Einstein also discovered that when a photon of a specific wavelength collides with an excited atom, 2 photons are released concurrently with equal frequencies, a phenomenon otherwise known as “stimulated emission.”2,3

Laser is an acronym for light amplification by the stimulated emission of radiation. Theodore Maiman created the first laser in 1960 by using an energy source to energize solid ruby crystals.4 Since this seminal discovery, the variety and applications of lasers in medicine has expanded dramatically over the ensuing decades. Because of its accessibility, the skin was the object of many of the early experiments that sought to harness this powerful modality, and as a result over the years lasers have revolutionized the treatment of numerous cutaneous disorders.


In its simplest form, a laser device creates energy in the form of a beam of light that interacts with its target tissue. Light and other forms of electromagnetic radiation are composed of photons that travel at a constant velocity, or speed of light (c = 2.998 × 108 m/s) in ...

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