L is for LASER

argon-ion laser national cancer institute

An Argon-Ion Laser, used in Photodynamic therapy to treat cancer (Photograph: National Cancer Institute).

by Dr Daniel Sister

Lasers are one of the most significant inventions developed during the 20th century. They have found a tremendous variety of uses in electronics, computer hardware, medicine, and experimental science.

It is an acronym that stands for “Light Amplification by Stimulated Emission of Radiation.”  It is a coherent (meaning that it is all one wavelength, unlike ordinary light which showers on us in many wavelengths) and focused beam of photons;

Lasers have many uses in medicine, including laser surgery (particularly eye surgery), laser healing, kidney stone treatment, ophthalmoscopy, and cosmetic skin treatments such as acne treatment, cellulite and striae reduction, and hair removal.

Lasers are used to treat cancer by shrinking or destroying tumors or precancerous growths. The Lasers (as there are many different) work as a result of resonant effects. The output of a laser is a electromagnetic field. In a coherent beam of electromagnetic energy, all the waves have the same frequency and phase.

In a basic laser, a chamber called a cavity is designed to internally reflect infrared (IR), visible-light, or ultraviolet (UV) waves so they reinforce each other. The cavity can contain gases, liquids, or solids. The choice of cavity material determines the wavelength of the output. At each end of the cavity, there is a mirror. One mirror is totally reflective, allowing none of the energy to pass through; the other mirror is partially reflective, allowing approximately 5 percent of the energy to pass through.

As a result an electromagnetic field appears inside the laser cavity at the natural (resonant) frequency of the atoms of the material that fills the cavity. The waves reflect back and forth between the mirrors. The output may appear as a continuous beam, or as a series of brief, intense pulses.

The ruby laser, a simple and common type, has a rod-shaped cavity made of a mixture of solid aluminum oxide and chromium. The output is in pulses that last approximately 500 microseconds each. The output is in the red visible range.

A blue laser has a shorter wavelength than the red laser, and the ability to store and read two to four times the amount of data.

The helium-neon laser is another popular type. As its name implies, it has a cavity filled with helium and neon gases. The output of the device is bright crimson. Other gases can be used instead of helium and neon, producing beams of different wavelengths.

Argon produces a laser with blue visible output. A mixture of nitrogen, carbon dioxide, and helium produces IR output.

What Is Skin Resurfacing?

Laser skin resurfacing is a broad term. It basically means the removal of skin. It can range from light, superficial removal of skin to deep removal of skin that requires anesthesia, considerable downtime, and side effects.

Skin resurfacing doesn’t have to be over the entire face. It can be restricted to a small area or a single spot on the face.

It can treat a range of problems:

  • Fine lines
  • Wrinkles
  • Loose or sagging skin (tightening)
  • Rough texture
  • Acne scarring
  • Large pores
  • Hyperpigmentation
  • Vascular lesions
  • Hair removal
  • Tattoo removal

The heat from laser light also induces the body’s natural wound response. During the wound healing process, new skin is formed. So artificially creating a “wound” in skin is how we get skin to look fresher and thicker.

The heat from the light also destroys colour targets, such as melanin (pigment) and haemoglobin (the protein in blood that gives it the red colour). This kind of targeting allows laser light to treat pigmented areas and vascular (blood-related) conditions, such as spider veins or varicose veins.

Ablative vs Non-Ablative

Ablative means the outer layers of skin are destroyed (removed).

This happens when the laser heats the water in the skin to a boiling point which vaporizes the skin cells. This method of destroying skin is known as a controlled burn.

The skin has a strong response to a controlled burn. If it’s deep, the skin becomes red, weepy, and raw. Healing takes time (known as downtime or recovery period), and there are side effects, such as redness, peeling, flaking, and tender skin, but the end result is new skin!

Collagen is re-deposited as a result of the body’s wound healing process, and new skin forms. The dermis becomes thicker.

Unfortunately, while Lasers tighten collagen, they don’t tighten elastin.

These most common ablative lasers are:

  • Er: YAG (called “erbium YAG”)
  • CO2

Only lasers are ablative. IPL and LED light treatments, which are other forms of light treatments, are not ablative; they don’t remove skin.

Non-Ablative

Non-Ablative means no skin is removed. The epidermis (outermost layer of skin) is left intact.

The light energy only targets and affects the deeper layers of skin. The light heats the water in the skin, but rather than vaporizing the skin cells, it causes the coagulation of blood vessels. This in turn leads to skin peel off through the natural shedding process (desquamation).

The following kinds of light treatments are considered non-ablative:

  • IPL (Intense Pulsed Light)
  • Visible Light Lasers (see list below)
  • Near Infrared Lasers (see list below)

Fractional / Fractionated

Fractional (or fractionated) resurfacing is a type of resurfacing that is gentler than traditional resurfacing.

Fractional means only part of the surface of skin is ablated (removed) by a laser. The laser beam is “fractionated” into a pattern where some parts of the skin are destroyed, and the other parts are left intact.

laser skin patternA pattern could be a grid like the one shown in the picture here. The red dots is where the skin has been ablated. The non-red portions are intact skin.

When part of the skin is left alone (intact), the healing time for the total treated area is faster, and there are fewer complications. This makes fractionated lasers more appealing than non-fractionated lasers.

The first fractionated laser was Fraxel, which is a fractionated CO2 laser. You may sometimes hear a fractionated treatment called a “Fraxel” even if it’s not actually done by a Fraxel laser.

Today, other lasers (called by different names) can accomplish the same things as a Fraxel laser. For example, the Er:YAG laser can be fitted with a pixelated tip, which can perform fractional resurfacing.


Common Lasers: list of some common lasers, from the shortest to longest wavelength.

In the Visible Light Spectrum:

Argon (blue-green, 488-514 nm)
KTP (green, 532 nm)
Pulsed Dye (yellow, 577-585 nm)
Ruby (red, 694 nm)

In the Infrared Spectrum:

Alexandrite (near infrared, 755 nm)
Diode (near infrared, 800-900 nm)
Nd: YAG (near infrared, 1064 nm)
Erbium: YAG (mid infrared, 2940 nm)
CO2 (far infrared, 10600 nm)