How a Fractional CO2 Laser Works
A fractional CO2 laser is a sophisticated skin resurfacing device that treats signs of aging, sun damage, acne scars, and other skin imperfections by delivering precise beams of light energy deep into the skin. Its operation is based on two key principles: selective photothermolysis and the fractional approach.
Laser Generation & Target:
The device generates an infrared laser beam using carbon dioxide (CO2) gas as the lasing medium. This beam has a specific wavelength of 10,600 nanometers.
This wavelength is highly absorbed by water, which is the primary component of cells in the epidermis (outer layer) and dermis (deeper layer) of the skin. Water acts as the chromophore (target).
Fractional Delivery (Creating Micro-Treatment Zones – MTZs):
Unlike older lasers that treated the entire surface area continuously, the key innovation is the “fractional” component.
The laser beam is split by a specialized scanner or optic system into an array (grid pattern) of hundreds to thousands of microscopic, focused beams.
Each microscopic beam creates a tiny, controlled column of injury in the skin, known as a Microscopic Treatment Zone (MTZ). These MTZs are typically between 80-300 microns in diameter.
Crucially, the skin between these MTZs remains completely untouched and intact.
Precise Ablation & Coagulation (Action within each MTZ):
Within each targeted MTZ, the intense CO2 laser energy is instantly absorbed by the water in the skin cells.
This causes extremely rapid heating:
Ablation: The top layers of tissue within the MTZ are instantly vaporized (ablated). This removes damaged or unwanted surface skin.
Coagulation: Simultaneously, the heat spreads slightly to the surrounding tissue within the MTZ, causing controlled thermal coagulation (denaturation) of collagen and remodeling of the dermal structure.
This dual action (ablation + coagulation) creates microscopic vertical channels of treated tissue surrounded by healthy, untreated skin.
Healing Response & Skin Remodeling:
The intact skin between the MTZs plays a vital role. It acts as a reservoir of healthy cells.
These healthy cells rapidly migrate into the MTZs, promoting fast re-epithelialization (surface healing) – usually within a few days.
Deep in the dermis, the controlled thermal injury within the MTZs triggers a powerful natural wound healing response. Fibroblasts are stimulated to produce new collagen and elastin fibers over the following weeks and months.
This process of collagen remodeling is primarily responsible for the long-term improvements: smoother texture, reduced wrinkles and scars, improved skin tightness, and a more even tone and color.
Key Advantages of the Fractional Mechanism:
Reduced Downtime: Healing is much faster than traditional ablative lasers because only a fraction (e.g., 10-30%) of the skin surface is treated at a time.
Reduced Risks: Lower risk of significant scarring, infection, or prolonged redness compared to full-surface ablation.
Enhanced Safety Profile: Allows safe treatment of darker skin types more effectively than older CO2 lasers.
Significant Efficacy: Achieves dramatic results comparable to traditional ablative resurfacing for many conditions, but with better safety and recovery.
In Summary: A fractional CO2 laser works by delivering a grid of precisely focused, microscopic beams of 10,600nm light. These beams create columns of ablated and coagulated tissue (MTZs) while leaving surrounding skin healthy. The intact skin enables rapid healing of the surface, while the deep thermal injury within the MTZs stimulates robust collagen production and remodeling, leading to significant skin rejuvenation with a favorable safety and recovery profile.
