Types of laser treatment, and what each one does

What makes one type of laser different from another?

Lasers differ in three ways: the wavelength of light, how long each pulse lasts, and whether the beam removes the skin surface or leaves it intact. Those choices decide what a laser can treat, how much downtime follows and how it behaves on Asian skin.

• Wavelength sets the target. Each wavelength is absorbed most by a particular target, called a chromophore: melanin in brown spots and hair, haemoglobin in red vessels, or water in all skin tissue. Light the target absorbs well turns into heat, or a shock wave, inside it.
• Pulse length sets the action. Very short pulses, measured in nanoseconds (Q-switched) or picoseconds (pico), break pigment particles apart. Longer millisecond pulses heat a whole hair follicle or spot.
• Ablative or non-ablative sets the recovery. Ablative lasers vaporise a thin layer of tissue; non-ablative lasers heat the dermis under an intact surface.
• Fractional or full-field sets how much skin is treated. A fractional laser treats a grid of microscopic columns and leaves untouched skin between them, which shortens healing.

The idea that matching wavelength and pulse length to a target lets a laser treat it while sparing the surrounding skin was set out in a 1983 paper on selective photothermolysis, and it still underpins every laser in this guide. At SkinRev Lab, all medical lasers are performed by Dr Sin Yong after a consultation; the full list sits on the medical treatments page. The sections below group the lasers by what they do, then compare them in one table. If you would rather start from your skin concern than from the device, see our guide to laser treatment by concern.

Picosecond and Q-switched lasers: for pigment and tattoo ink

Picosecond (pico) and Q-switched lasers treat pigment by delivering extremely short pulses that break melanin or tattoo ink into fine particles the body can clear. A Q-switched pulse lasts nanoseconds; a picosecond pulse is about a thousand times shorter, so more of its effect is mechanical and less is heat. That is one reason medium to darker skin often suits pico.

A 2021 systematic review of 77 studies graded the evidence for picosecond lasers as strongest for tattoo removal, with moderate-level evidence for melasma, skin rejuvenation and scar revision. Melasma is therefore usually treated within a wider plan rather than by laser alone.

SkinRev offers three lasers in this group, all performed by Dr Sin Yong:

• Pico Laser (T2 Frax Radiance): a 785 nm picosecond wavelength with 532 nm and 1064 nm nanosecond outputs, for sun spots, freckles, post-acne marks and tattoos. The same platform runs Dr Sin Yong's T2 protocol for cosmetic tattoo and embroidery removal in selected cases.
• R2 Glow Laser: 1064 nm picosecond and Q-switched pulses, with 532 nm for superficial spots, for dull, uneven tone and scattered sun pigment.
• Laser Toning: low-fluence 1064 nm Q-switched pulses passed several times across the skin, for uneven tone, post-acne marks and darkened underarms.

Pico lasers cannot treat moles, deep scars or sagging, and a spot that is changing or irregular is examined before any laser. Which of the three suits you depends on the type and depth of the pigment, which is why the choice is made at consultation.

Long-pulsed alexandrite and Nd:YAG lasers: for hair, sun spots and deep heating

Long-pulsed lasers spread each pulse over milliseconds, so instead of shattering pigment they heat a whole target, such as a hair follicle or a flat brown spot. The two common wavelengths behave differently on Asian skin. The 755 nm alexandrite wavelength is strongly absorbed by melanin, which makes it efficient on fair to medium skin and on finer dark hair. The 1064 nm Nd:YAG wavelength is absorbed less by melanin and reaches deeper, so it is usually chosen for tanned or darker skin.

• Alexandrite Laser (755 nm, long-pulsed) treats flat, well-defined sun spots and freckles in the outer skin. Spots darken and form fine crusts that usually flake off in about one to two weeks. It is not a treatment for melasma, and deeper blue-grey pigment needs a Q-switched or picosecond laser instead.
• Laser Hair Removal uses both 755 nm and 1064 nm, chosen for your skin tone and hair. Sessions are spaced about four to eight weeks apart. Dark hair responds; white, grey, red or very fair hair responds poorly.
• Time Freeze Laser LCLR® uses long-pulsed 755 nm and 1064 nm light as bulk heating, scanned across the jowls, jawline, neck and under the chin. It is not a fractional laser, the skin surface is not broken, and downtime is usually none.

Long-pulsed lasers are deferred on freshly tanned or sunburnt skin, and Dr Sin Yong may test a small area first on darker or sensitive skin. These lasers suit people whose concern sits where the light can reach it: hair with dark pigment, spots in the outer skin, or soft fullness and mild looseness along the jaw and neck.

Fractional non-ablative lasers: for texture, pores and fine lines

A fractional non-ablative laser heats a grid of microscopic columns in the dermis while the skin surface stays intact, so collagen can remodel with only short-lived redness. The fractional idea was introduced in a 2004 study in which each treated column was about a tenth of a millimetre wide; the surface over the columns had healed within a day.

SkinRev offers three non-ablative fractional or resurfacing protocols, each performed by Dr Sin Yong:

• FSX Laser: Dr Sin Yong's protocol combining 1540 nm erbium-glass and 1927 nm thulium energy, for texture, pores, fine lines, shallow scars and stretch marks. Redness usually settles within hours to a day or two; light scabs are possible after stronger passes.
• 少女光 Laser: a 675 nm red-light fractional laser with contact cooling, used for redness-prone skin, enlarged pores and uneven texture. Expect redness and warmth for a few hours and possible dryness or tiny dark dots for a few days.
• Luminescence Laser: a non-ablative protocol for surgical scars and red or raised scars, and one part of a keloid plan where suitable. Expect mild redness for a few hours and some dryness or slight swelling for one to three days.

Because change builds as collagen remodels, these lasers are planned as a course with sessions spaced weeks apart. They suit people who want gradual improvement in texture or pores without a week off work, and who can keep up daily sun protection during the course.

Fractional CO2 and other ablative lasers: for deeper scars

An ablative laser removes a thin layer of skin, and a fractional ablative laser does this in a pattern of microscopic channels; it gives the strongest resurfacing effect and the longest recovery of the lasers in this guide. The CO2 laser emits at 10,600 nm, a wavelength absorbed by water in the skin, so each channel is vaporised and the heat around it prompts the dermis to remodel. DermNet notes that full healing after ablative resurfacing usually takes about two weeks, ranging from one to four weeks with treatment depth.

At SkinRev Lab, S3 Resurfacing is Dr Sin Yong's fractional CO2 scar protocol for deeper acne scars, flat or depressed surgical and injury scars, and textured stretch marks. Expect about 5 to 7 days of swelling and fine crusts, with pinkness fading over weeks. Desk work from home is often possible from day two or three; plan around a week of social downtime before returning to the office.

For mixed or deeper acne scars, 4D Scar Reconstruction combines subcision, TCA CROSS, fractional CO2 and an injectable where volume is lost, chosen scar by scar. Where light is not the right tool, RF microneedling delivers heat through fine needles instead, with redness and mild swelling for one to three days.

SkinRev's resurfacing laser is fractional CO2; full-field ablative resurfacing is not on its treatment list. Fractional CO2 suits people with scars that lower-downtime lasers have not moved, who can plan for a week of visible healing and strict sun protection afterwards.

IPL vs laser: how they differ, and why SkinRev uses lasers

IPL (intense pulsed light) is not a laser. A laser emits a single wavelength, while each IPL pulse contains many wavelengths from a flashlamp, refined with filters for different targets. Both turn light into heat inside coloured targets, and IPL is non-ablative, so downtime is usually short. DermNet describes IPL being used for vascular and pigmented lesions, unwanted hair and some acne, and notes that skin pigment can absorb too much energy, occasionally causing blistering or darker or paler patches.

• Light source: a laser uses one wavelength; IPL uses a filtered band of many wavelengths.
• Targeting: a laser wavelength and pulse can be set for one target at a chosen depth; IPL spreads energy across a range of wavelengths.
• Typical course: DermNet describes IPL courses of around four to six sessions, three to six weeks apart.
• At SkinRev: IPL is not offered.

SkinRev does not offer IPL. Dr Sin Yong uses lasers, where the wavelength can be chosen for the target and for your skin type: 755 nm and 1064 nm for hair removal, picosecond and Q-switched wavelengths for pigment, 675 nm for redness-prone skin and pores, and fractional lasers for texture and scars. Mention any previous IPL or laser sessions at your consultation, with dates, so the plan can take them into account.

Types of laser treatment compared

The main laser types differ in wavelength, uses and downtime, as compared below. Downtime comes from each SkinRev treatment page and varies with settings.

Lasers on Asian skin: why temporary darkening is the main risk

On most Singaporean skin the main laser risk is temporary darkening, called post-inflammatory hyperpigmentation (PIH), rather than burns. Many people in Singapore have Fitzpatrick skin types III to V, where melanin in the surface competes with the intended target for laser energy. A review of laser treatment in Asian patients found PIH to be one of the adverse reactions seen more often than in Caucasian skin, and stressed careful patient selection and planning to lower that risk.

How Dr Sin Yong adjusts laser treatment for Asian skin:

• Choosing 1064 nm, which melanin absorbs less, for darker skin where it suits the concern.
• Using conservative settings, and a test area first for darker skin, skin that tans easily or uncertain tattoo inks.
• Deferring treatment during a tan, during pregnancy and while taking light-sensitising medicines.
• Asking you to use broad-spectrum sunscreen daily and keep to shade between sessions; after fractional CO2, daily sunscreen once the skin has closed.
• Pausing retinoids and exfoliating acids around treatment, where he advises it.

Watch for temporary darkening in weeks two to eight after a pigment laser, and report any unusual lightening or darkening so settings can be adjusted. Melasma needs particular care because heat can make it darker, so it is treated within a medical plan rather than by laser alone. If you take an oral acne medicine, are prone to cold sores or are pregnant, tell Dr Sin Yong before any laser is planned.

How Dr Sin Yong chooses between laser types

The laser is chosen after a diagnosis, not before. Dr Sin Yong first works out what the concern is, how deep it sits and what your skin type allows. Brown marks, for example, can be sun spots, freckles, melasma, post-acne marks or deeper blue-grey pigment, and each needs a different wavelength or a different approach altogether. A spot or mole that is changing or irregular is examined before any laser is considered.

At the consultation he will:

• examine the concern and your skin type, and ask about tanning, pregnancy, medicines and cold sores;
• explain which laser he recommends, the likely number of sessions, the downtime and the risks;
• give the price at consultation, once he has examined you;
• tell you if a laser is not the right tool, or if a non-medical treatment or no treatment suits you better.

Lasers cannot do everything. Pico lasers do not treat moles, deep scars or sagging, and no laser in this guide replaces surgery for heavy, loose skin. For early sagging along the jaw, lifting treatments such as HIFU are often the closer fit; for depressed acne scars, a combined plan may work better than any single laser.

After treatment, contact the clinic if blistering spreads, the area weeps, or pain increases after day two; after fractional CO2, also for yellow crusts, worsening pain or darkening. To start, WhatsApp SkinRev Lab on +65 8266 9585 with your concern and any previous laser or IPL treatment.