Each spot produces a narrow treatment column, while spaces between the columns remain untreated. This fractional arrangement allows the machine to treat only a selected percentage of the surface during each pass rather than ablating the entire area continuously.
Step 1: The source generates energy
The CO2 laser source contains a carbon-dioxide-based gas mixture that is electrically excited to generate laser energy at approximately 10,600 nm — a wavelength absorbed by water in tissue.
The source is one of the most important and expensive parts of the machine. Its quality affects power stability, pulse consistency, beam profile, starting reliability, operating life, service requirements and treatment repeatability.
Step 2: Pulse electronics shape the energy
The machine's electronics control how the energy is released. Depending on the system, the source may operate through different pulse formats or delivery modes, which affect how quickly energy is delivered and how heat spreads in tissue.
The relevant questions are not how many modes are displayed, what the maximum wattage is, or whether the screen says ultrapulse. Verify instead:
- Whether the pulse modes are produced by the source or only represented in software
- Whether pulse duration is stable
- Whether energy delivery is repeatable
- Whether the output has been measured
- Whether the source specifications match the marketing claims
A mode name shown on a touchscreen does not independently prove that the machine has the corresponding pulse technology.
Step 3: Energy travels through the articulated arm
CO2 energy is commonly transmitted from the source to the handpiece through an articulated arm containing optical mirrors. The arm has several movable joints, each of which must keep the beam correctly aligned while the practitioner moves the handpiece.
Arm quality affects beam transmission, handpiece movement, spot stability, energy loss, treatment comfort, long-term alignment and maintenance. A poorly aligned arm may cause inconsistent transmission or an irregular spot.
Step 4: Mirrors direct the beam
Internal mirrors guide the beam through every joint. These components must remain clean, correctly aligned and suitable for the CO2 wavelength.
Damage, contamination or misalignment can reduce transmitted energy even when the screen continues to show the selected output. This is why screen wattage and energy arriving at the treatment tip should not be treated as identical.
Step 5: The focusing system forms the spot
Before reaching tissue, the laser passes through focusing optics. The lens and handpiece determine the beam's focal characteristics and spot formation.
A high-quality spot should be predictable, properly focused, consistent, appropriately shaped and stable when the arm is moved. A poor spot may appear distorted, oversized, irregular or inconsistent across the treatment field.
Step 6: The scanner moves the beam
The fractional scanner contains a high-speed beam-positioning mechanism. It places the laser into a selected pattern — square, rectangle, circle or another available shape — and divides that area into individual dots.
Depending on the machine, the operator may adjust pattern shape, treatment-area size, dot spacing, density, scanning sequence, energy, pulse mode and repeat function.
Step 7: Tissue water absorbs the energy
When the beam reaches tissue, water absorbs the energy. Rapid heating can cause controlled vaporisation and ablation, and heat around the treatment column can produce coagulation and a surrounding thermal zone.
The balance between ablation and thermal effect depends on the device and the selected delivery characteristics. This is why maximum power alone does not define treatment quality.
Step 8: Microscopic columns are created
Each scanned dot creates a microscopic treatment zone. The scanner places multiple zones in a fractional pattern, leaving untreated tissue between them, which supports faster surface recovery than traditional full-field ablative resurfacing while the treated columns initiate repair and remodelling.
Step 9: Healing and remodelling begin
Following treatment, the body begins a repair response. The treated columns undergo re-epithelialisation and remodelling over time, so change is progressive rather than immediately visible.
The result depends on correct indication, the skin condition being treated, skin type, device performance, treatment selection, practitioner skill, healing response, aftercare, and the number and spacing of sessions.
Depth, density and what they actually depend on
Treatment depth cannot be judged from a single displayed number. It is influenced by energy delivered per spot, pulse duration, peak power, spot diameter, beam profile, scanner dwell time, number of passes, tissue water content, skin characteristics, contact and focus, and calibration of the source and scanner.
Claims such as “4 mm depth” or “deepest CO2 laser” should be supported by technical documentation rather than a sales demonstration.
Density describes how closely the dots are placed, or what proportion of the area is treated. Higher density does not automatically produce a better result — it places more microscopic zones in the area, which also increases cumulative thermal injury and recovery requirements. Density must be selected by a qualified practitioner for the indication, skin type, machine and protocol.
Why paper tests can be misleading
Vendors commonly demonstrate CO2 machines by firing the laser onto paper, cardboard, fruit, wood or acrylic. These demonstrations may show that energy is being emitted, but they do not establish accurate clinical output, correct pulse duration, uniform tissue effect, safe treatment depth, scanner calibration, beam stability, suitability for a particular indication, or regulatory compliance.
Displayed power versus delivered power
The wattage shown on the screen is a selected machine value. Actual energy reaching the treatment point may be influenced by source condition, power-supply stability, mirror contamination, optical alignment, articulated-arm losses, lens condition, scanner optics, source ageing and calibration.
For this reason, professional technical evaluation may include measuring output with an appropriate calibrated laser power or energy meter.
Maximum wattage can be relevant for certain requirements, but it does not reveal pulse quality, beam profile, stability, scanner accuracy, optical transmission, source lifespan, safety performance, software reliability or serviceability. A stable, accurately controlled machine may be worth more to a clinic than an exaggerated maximum-power claim.
Frequently Asked Questions
How does a CO2 fractional laser work?
A CO2 source generates a 10,600 nm beam, an articulated arm carries it to the handpiece, and a scanner places it as a pattern of microscopic dots. Water in the tissue absorbs the energy, producing controlled ablation and a surrounding thermal zone.
Does higher wattage mean a better machine?
Not necessarily. Wattage says nothing about pulse quality, beam profile, stability, scanner accuracy, optical transmission, source lifespan or serviceability.
Is the wattage on the screen the power reaching the skin?
No. Delivered energy is affected by source condition, power-supply stability, mirror contamination, alignment, arm losses, lens condition and calibration. Measuring output with a calibrated meter is the way to know.
Is a paper-burning demonstration proof of performance?
No. It shows energy is being emitted. It does not establish pulse duration, uniformity, depth, scanner calibration or beam stability.
What decides treatment depth?
Energy per spot, pulse duration, peak power, spot diameter, beam profile, dwell time, passes, tissue characteristics and calibration - not a single number on a screen.