What Is a Laser REALLY?



The term laser is as common as almost anything in our lives. But what is a laser? First, it is an acronym, standing for Light Amplification by Stimulated Emission of Radiation. And that name is a great start in defining a laser. Essentially, a laser is a device that produces amplified light by using stimulated emission of radiation.

Now before the term radiation scares you, it’s referring to radiation in the broadest way, which is any electromagnetic wave, not the radiation we associate with bodily harm. In a laser, electricity or another form of energy is deposited into a medium, such as crystal. The atoms in the medium are stimulated to emit radiation, often in the form of infrared, visible, or ultraviolet waves. Those waves are concentrated to produce an amplified light beam.

Unlike a flashlight, a laser beam has three particular characteristics: (1) monochromatic, or made of exactly the same color or wavelength, (2) collimated, or focused in one direction, and (3) coherent, or having synchronized waves.

The applications of lasers are ubiquitous, such as cutting (laser cutter), communications (barcode scanner, fiber optics), and defense (laser-guided weaponry). Of course, lasers are also used in medicine. In aesthetic medicine, they are commonly used to remove skin lesions or hair. They can also be used to promote collagen growth.

For example, the laser we use at our practice is the MOTUS. It produces an Alexandrite laser beam with a wavelength of 755 nm, so these waves are a little longer than red light at 620-750 nm, hence “infrared.” Think of it as a concentrated beam of dark red light. The wonderful part is that melanin, or the pigment in our skin and hair, likes to absorb this wavelength. In hair removal, most of the energy in the laser beam is absorbed by the hair and surrounding follicle, which essentially destroys that unit from producing any more hair. Only follicles in a certain stage of maturation are susceptible to this process, so multiple treatments are necessary. The same principle applies to a mole. The cells holding the melanin absorb the energy from the beam and are subsequently destroyed.

The MOTUS also produces a Nd:YAG laser beam at a wavelength of 1064 nm, which is also infrared. At this particular wavelength, the energy is absorbed by hemoglobin more than melanin, so it useful for unsightly blood vessels. In addition, the beam has better skin penetration and delivers thermal energy to the dermis while bypassing the epidermis. In other words, the surface of the skin is spared with no downtime, while the connective tissue underneath is heated to stimulate collagen production, hence the name photorejuvenation or laser collagenesis.

These are just a few examples of laser applications in aesthetic medicine. New lasers as well as new protocols are constantly being developed and it is our responsibility as physicians to stay current in this ever-expanding field, so that we can deliver the best results safely.