Six platforms, and the physics behind them.

Diode hair removal works on selective photothermolysis: melanin in the hair shaft and follicle absorbs light more strongly than the surrounding skin, so a pulse tuned to the right wavelength and duration heats the follicle while the tissue around it stays comparatively cool. 808nm is the workhorse because it balances melanin absorption against penetration depth. Adding 755nm raises absorption for finer, lighter hair; 1064nm absorbs less but travels deeper and is the safer choice on darker skin, where epidermal melanin competes for the same energy.

Pulse width is what separates a comfortable treatment from a burn. Longer pulses — the 10 to 125ms range these machines cover — deliver energy slower than the epidermis can be damaged but faster than the follicle can shed heat. SHR and stacking modes take this further, running many low-fluence passes at high repetition rates to build follicular temperature cumulatively rather than in one shot. Contact cooling at around 5°C holds the surface down throughout, which is why gel is not required.

Pigment removal is a mechanical problem, not a thermal one. A picosecond pulse is shorter than the time the target needs to conduct heat into surrounding tissue, so the absorbed energy has nowhere to go and the particle fractures under the pressure wave instead of cooking. Smaller fragments are easier for the body to clear. Nanosecond Q-switched pulses work on the same principle with a longer pulse and a larger thermal component, which is why both remain in use.

Wavelength selects the target. 1064nm penetrates deepest and is absorbed well by black and dark blue ink, and it passes through epidermal melanin more safely than shorter wavelengths — which matters on darker skin. Frequency-doubled 532nm is absorbed strongly by red and orange ink and by superficial pigment. The dye handpieces at 585nm and 650nm extend that coverage to inks the two primary wavelengths address poorly.

A top-hat beam profile means the energy is distributed flat across the spot rather than peaking in the centre as a Gaussian beam does. That is what allows fluence to be raised without a hot core at the middle of every pulse, and it is the difference between a consistent result across a treatment area and a mottled one.

Ablative and non-ablative resurfacing differ in one respect: whether the stratum corneum is removed. At 10,600nm, water absorbs nearly all incident CO₂ energy within a few micrometres, so the pulse vaporises a controlled column of tissue and leaves a thin coagulated rim around it. Fractionating that into a pixel grid means only part of the treated area is ablated in a pass, and the untreated bridges of tissue between columns are what drive re-epithelialisation.

Pixel energy sets column depth, density sets how close the columns sit, and the scan pattern determines the order in which they are placed — scattered patterns spread the thermal load in time as well as space. Those three parameters are independent on these machines, so depth and coverage are set separately rather than chosen from presets.

1927nm sits on a water absorption peak roughly an order of magnitude higher than 1550nm, which confines its energy to the epidermis and upper dermis where superficial pigment lives. 1550nm passes deeper and creates columns of coagulation without ablation. Neither breaches the skin surface, so the barrier stays intact — a different recovery profile from CO₂, not a better or worse one.

Focused ultrasound is the only modality here that deposits energy below the surface without depositing it on the way in. The beam converges at the cartridge's focal depth, so intensity at the focus is high enough to form a discrete coagulation point while the tissue the beam passed through stays below the threshold. Cartridge depth is fixed by its transducer geometry, which is why depth is selected by changing cartridges rather than by turning a dial.

RF microneedling reverses that geometry: the needles carry energy through the surface and release it at a set depth. Insulated needles emit only from the exposed tip, sparing the shaft and the epidermis above it. Non-insulated needles heat the full tract. Having both, with depth adjustable across a 0.2 to 7.0mm range and pulse duration from 10 to 900ms, is what lets one platform treat thin periorbital skin and thick submental tissue.

Radiofrequency is colour-blind. Because it heats by tissue impedance rather than by chromophore absorption, it does not target melanin, which is why RF-based treatment is not constrained by skin type in the way a laser is.

Hydra dermabrasion combines mechanical exfoliation with vacuum extraction and fluid delivery in a single pass: the tip abrades while negative pressure lifts debris away and solution is fed to the skin surface. A 360-degree rotating tip changes its angle of attack continuously rather than tracking a fixed spiral, which distributes the abrasive action more evenly across the pass.

The rest of a multifunction platform is a sequence, not a single mechanism — jet peel at pressure, oxygen infusion, microcurrent, three-polar RF at 5MHz, LED, ultrasonic. What makes it commercially useful is that the whole protocol runs from one trolley with the client in one chair.

Motorised mesotherapy injection addresses consistency rather than depth. Depth is held at the set value in 0.2mm steps across a 9-pin 32G array and dose is metered per shot, so the variable that changes between operators — hand feel — is removed from the procedure. Vacuum assistance draws tissue toward the needles, which matters most on lax or thin skin.

HIFEM does not act on fat or skin directly. A pulsed magnetic field induces a current in motor neurons, which depolarises them and contracts the muscle involuntarily. At low repetition rates the result is individual twitches; above roughly 40Hz the contractions fuse into a sustained tetanic contraction that voluntary effort cannot reproduce or hold. Field intensity, measured in tesla at the applicator, is the specification that determines how much tissue is recruited.

Cryolipolysis works from the opposite direction, exploiting the fact that adipocytes crystallise at temperatures the surrounding dermis, vasculature and nerve tissue tolerate. That differential is what makes controlled cooling selective. The vacuum draws a fold into the cup so the cooling plates contact it from both sides rather than one, which is why cup geometry and fit matter as much as the set temperature.

Vacuum roller platforms combine mechanical and thermal action in the same pass: negative pressure lifts and holds a fold of tissue, motorised rollers work it, and RF at 1 to 5MHz heats it, with a 940nm diode adding a separate absorption path. Treatment head size — from 4×7mm up to 40×60mm here — scales the same mechanism from facial work to full-back passes.

A multi-technology workstation shares one power supply, one cooling loop and one console between several handpieces, each of which works on its own principle. The diode handpiece relies on selective photothermolysis in the hair follicle; the IPL handpiece emits broadband light from a flashlamp and uses a cut-off filter to choose which part of the spectrum reaches the skin; the Nd:YAG handpiece delivers short, high-energy pulses at 1064nm and, frequency-doubled, at 532nm to fragment ink and pigment; RF and RF microneedling heat tissue by its electrical impedance rather than by colour.

What decides how well the handpieces share one chassis is heat. A diode bar running a full-leg protocol and an IPL flashlamp both dump energy into the same water loop, which is why these consoles combine water circulation with TEC or compressor cooling and a chilled sapphire contact window. The cooling specification is the number to read before the list of functions, because it sets how long any one handpiece can work before the machine asks it to rest.

HIFU, where it is included, is the one module that does not use light or current: a transducer focuses ultrasound to a point at a fixed depth set by the cartridge, from about 1.5mm for superficial facial work to 13mm for body tissue, and heats a small thermal zone there without affecting the surface above it.

Intense pulsed light is not a laser. A xenon flashlamp emits a broad spectrum, and a sapphire filter removes everything below its cut-off, so a 560nm filter passes light from 560nm upward. Lower cut-offs reach the absorption peaks of haemoglobin and superficial melanin and suit redness and pigment; higher cut-offs such as 640, 690 and 755nm travel deeper and suit hair. Fluence and pulse structure then decide how much of that light is deposited, and how fast.

A 980nm diode laser works on a single wavelength where haemoglobin and water both absorb. Delivered through a fibre to a small spot of 0.5 to 3mm, it heats an individual vessel while the tissue beside it absorbs comparatively little, which is why small, fine vessels are treated one at a time rather than with a wide window. The spot size is matched to the vessel diameter, not to the area.