The Science of Laser Hair Removal
How Laser Hair Removal Works
Discover the science behind laser hair removal and learn why our advanced four-wavelength diode laser delivers safe, effective treatment for a wide range of skin and hair types.
Book a Free Consultation & Patch TestSection 1
What is Laser Hair Removal?
Laser hair removal is a medical procedure that uses concentrated beams of light to permanently reduce unwanted hair. Unlike shaving, waxing, or threading — which remove hair temporarily — laser treatment targets the hair follicle itself, inhibiting its ability to produce new hair growth.
The scientific principle behind laser hair removal is called selective photothermolysis. This means the laser selectively delivers heat to a specific target — in this case, melanin, the pigment that gives hair its colour — without damaging the surrounding skin tissue.
Laser energy targets melanin
The laser emits a precise wavelength of light that is strongly absorbed by melanin in the hair shaft and follicle.
Heat damages the follicle
The absorbed light energy converts to heat, which travels down the hair shaft to the follicle and damages the papilla — the structure responsible for producing new hair.
Surrounding skin is protected
Because the laser is calibrated to target melanin specifically, and because the pulse duration is carefully controlled, the heat is confined to the follicle. The surrounding skin tissue does not absorb the same wavelength and is therefore largely unaffected.
How selective photothermolysis works
Laser Beam
Skin Surface
Largely unaffected — laser passes through
Hair Shaft (Melanin)
Absorbs laser energy → converts to heat
Hair Follicle & Papilla
Heat damages papilla → inhibits regrowth
The laser's wavelength is calibrated so that melanin in the hair absorbs the energy far more readily than the surrounding skin tissue — this is the principle of selective photothermolysis.
Common Question
If the Skin Also Absorbs Laser Energy, Why Doesn't It Burn?
This is one of the most common questions about laser hair removal — and it's an excellent one.
The simple answer is that the skin does absorb some of the laser energy, but the hair follicle absorbs significantly more. Successful laser hair removal relies on selective photothermolysis, where the laser is carefully calibrated to heat the hair follicle to a temperature that damages the cells responsible for hair growth — while keeping the surrounding skin below the threshold for thermal injury.
This is achieved through a combination of factors:
Higher melanin concentration in hair
The hair contains a much higher concentration of melanin than the surrounding skin, allowing it to absorb more laser energy.
Precisely timed pulse duration
The laser pulse is precisely timed so the larger hair follicle continues to heat while the skin begins cooling — a principle known as thermal relaxation time.
Continuous sapphire contact cooling
The sapphire crystal tip on our laser handpiece protects the surface of the skin before, during, and after every pulse, keeping the epidermis cool while energy penetrates to follicle depth.
Individually adjusted settings
Treatment settings are adjusted according to your skin type, hair colour, and hair thickness — ensuring the energy delivered is appropriate for your specific combination.
When can skin become damaged?
If too much energy is used, the wrong settings are selected, or recently tanned skin is treated, the skin can absorb enough heat to become damaged. This is why choosing an experienced practitioner and using a high-quality medical laser is just as important as the treatment itself.
The key principle
"The goal isn't to stop the skin absorbing laser energy completely — that isn't possible. The goal is to ensure the hair follicle absorbs enough energy to be damaged while the surrounding skin remains protected."
~70°C
Follicle target temperature
<45°C
Skin surface (cooled)
Section 2
Understanding the Hair Growth Cycle
One of the most important things to understand about laser hair removal is that it can only treat hairs that are in a specific phase of their growth cycle — and this is precisely why multiple sessions are required.
Anagen
Active Growth Phase
During the anagen phase, the hair is actively growing and the follicle is fully connected to the papilla — the blood supply that nourishes it. This is the only phase in which laser treatment is effective. The laser energy travels down the hair shaft to the follicle, where it is absorbed and converted to heat, damaging the papilla and inhibiting future growth.
Catagen
Transition Phase
During catagen, the hair follicle begins to shrink and detaches from the papilla. The hair is no longer actively growing. Because the connection between the hair shaft and the follicle is breaking down, laser energy cannot travel effectively to the target — making this phase largely unresponsive to treatment.
Telogen
Resting Phase
In the telogen phase, the old hair is shed and the follicle rests before beginning a new anagen cycle. There is no active hair shaft present to conduct laser energy to the follicle. Treatment during this phase has no meaningful effect on hair regrowth.
Exogen
Shedding Phase
Exogen is sometimes described as a distinct sub-phase of telogen, during which the old hair is actively shed from the follicle. The club hair detaches and falls out — often accelerated by washing or brushing. The follicle is empty and dormant at this point. Like telogen, exogen hairs are not connected to the papilla and do not respond to laser treatment.
Section 3
Why Autumn & Winter Are Ideal
Laser hair removal can be performed safely throughout the year. However, many practitioners — and many patients — find that autumn and winter offer some practical advantages.
During the summer months, skin is often more pigmented due to sun exposure and tanning. Because the laser targets melanin, higher levels of melanin in the skin surface can reduce the contrast between the hair follicle and the surrounding skin — making it harder for the laser to selectively target the follicle without also affecting the skin.
Skin naturally contains less melanin in autumn and winter due to reduced sun exposure
Lower skin pigmentation increases the contrast between hair follicle and surrounding skin
Greater contrast allows the laser to target follicles more selectively and at higher energies
Patients are less likely to be sunbathing, making pre- and post-treatment aftercare easier to follow
Starting in autumn means you can complete a full course and be hair-free by summer
The ideal treatment timeline
Autumn Sep – Nov
Ideal start — skin melanin at its lowest
Winter Dec – Feb
Excellent conditions — continue your course
Spring Mar – May
Good — avoid sun exposure between sessions
Summer Jun – Aug
Possible — strict sun avoidance required
Section 4
Our 4-Wavelength Diode Laser
At Clinic Visjeune, we have always invested in the best available technology. We began with an IPL machine, which served us well in the early years. As our understanding of laser science deepened, we upgraded to a true diode laser — a significant step forward in precision and effectiveness.
After several years with that system, we undertook extensive research to identify the most advanced laser available. After evaluating multiple platforms, we chose our current 4-wavelength diode laser — by far the most effective machine we have used. The difference in results, comfort, and versatility has been remarkable.
Alexandrite Range
Best for: Fine & light hair
The 755nm wavelength has the highest melanin absorption of all four wavelengths, making it exceptionally effective at targeting hair follicles. Because it is so readily absorbed by melanin, it must be used with care on darker skin tones — but for lighter skin with fine or fair hair, it delivers outstanding results.
Classic Diode
Best for: All hair types
The 808nm wavelength is the gold-standard diode frequency, offering a strong balance between melanin absorption and deeper tissue penetration. It is effective across a broad range of hair and skin types and forms the backbone of most professional diode laser systems.
Deep Penetration
Best for: Deeper follicles
At 940nm, the laser penetrates deeper into the dermis, targeting follicles that sit lower beneath the skin surface. This wavelength is particularly useful for coarser, thicker hair and for body areas where follicles tend to be deeper.
Nd:YAG Range
Best for: Darker skin tones
The 1064nm wavelength has lower melanin absorption, which means it passes more safely through darker skin without being absorbed by surface pigment. This makes it the preferred wavelength for treating Fitzpatrick skin types V and VI, where other wavelengths carry a higher risk of skin reaction.
Section 5
Diode Laser vs. IPL
Both diode lasers and IPL (Intense Pulsed Light) devices are used for hair removal, and both can produce good results in the right hands. Understanding the difference helps you make an informed decision about your treatment.
IPL devices can produce good results, particularly on lighter skin tones with dark hair. The key difference is precision: a laser produces a single, coherent wavelength that can be precisely matched to the target chromophore, while IPL emits a broad spectrum that is filtered but not as tightly controlled. For clients with darker skin tones, finer hair, or those seeking the most predictable outcomes, medical-grade diode laser is generally the preferred choice.
Continuous Sapphire Contact Cooling
How it works
A sapphire crystal tip on the laser handpiece maintains continuous contact with the skin surface throughout treatment, actively cooling the epidermis to approximately 4°C.
Patient comfort
The cooling effect significantly reduces the sensation of heat during treatment. Most clients describe the experience as comfortable — a mild warmth rather than the sharp sting associated with older laser systems.
Skin protection
By keeping the skin surface cool, the sapphire tip protects the epidermis from thermal damage while allowing the laser energy to penetrate to the follicle depth where it is needed.
Reduced risk
Continuous cooling reduces the risk of post-treatment redness, blistering, and hyperpigmentation — particularly important when treating sensitive areas or darker skin tones.
Section 6
Sapphire Contact Cooling
One of the most significant advances in modern laser hair removal technology is integrated sapphire contact cooling. Rather than applying a cooling gel or using a separate cooling device, our laser handpiece incorporates a sapphire crystal tip that continuously cools the skin surface throughout the entire treatment.
This is not simply a comfort feature — it is a safety mechanism. By maintaining the skin surface at a consistently low temperature, the cooling system creates a thermal gradient: the skin surface stays cool while the laser energy penetrates to the follicle depth, where the heat is needed. This allows us to use higher energy settings safely, which translates directly into more effective treatment.
~4°C
Cooling temperature
High
Comfort level
Continuous
Skin protection
Minimal
Aftercare
Section 7
Suitable for All Skin Types
Skin type is one of the most important factors in laser hair removal. Clinicians use the Fitzpatrick Scale — a classification system that categorises skin into six types based on its response to sun exposure — to guide treatment settings and assess suitability.
Type I
Excellent
Very fair, always burns, never tans
Type II
Excellent
Fair, usually burns, tans minimally
Type III
Very Good
Medium, sometimes burns, tans gradually
Type IV
Good
Olive, rarely burns, tans easily
Type V
Good
Brown, very rarely burns, tans darkly
Type VI
Treatable
Dark brown/black, never burns
FAQs
Common Questions
Ready to Start Your Journey?
Book a free consultation and patch test at Clinic Visjeune. We will assess your skin type, answer your questions, and create a personalised treatment plan — with no pressure and no obligation.