When suitable laser energy is absorbed by pigment in the hair, that energy is converted to heat. The objective is controlled thermal damage to structures associated with future hair growth while managing heat at the surrounding skin.

This process is known as selective photothermolysis.

It is important to distinguish the technology from the simplistic idea that a laser beam merely travels down the centre of the hair and “burns the root”. Light absorption, heat transfer, hair pigment, hair-growth stage, skin pigmentation and treatment parameters all influence the response.

Professional Diode systems may use a single wavelength or provide multiple selectable wavelengths. Ultra Silk Plus, for example, provides 755nm, 808nm, 940nm and 1064nm through its Diode handpiece.

Hair-removal lasers take advantage of the fact that melanin absorbs light.

When an appropriate wavelength, fluence and pulse duration are used, energy absorbed by the pigmented hair creates heat within and around the follicular structure.

The treatment needs to produce enough controlled thermal effect to reduce future hair growth without creating excessive heating of the surrounding epidermis.

That is why professional hair removal depends on considerably more than the wavelength printed on a specification sheet.

Hair moves through several phases including anagen, catagen and telogen.

Laser treatment is generally most useful when there is actively growing, sufficiently pigmented hair connected to the follicular target. This is associated particularly with the anagen — active growth — phase.

At any one time, however, only a proportion of hairs within a treatment area will be at the same point in their growth cycle.

Repeated sessions spaced according to the treatment area allow practitioners to treat further hairs as they move into a more responsive growth stage.

The melanin that makes hair an effective optical target is also present within the epidermis.

As skin pigmentation increases, there is more competing epidermal melanin to consider. Practitioner assessment, wavelength selection, pulse parameters and cooling therefore become particularly important.

Longer wavelengths generally have lower relative absorption by melanin and different penetration characteristics from shorter wavelengths.

That is one reason multi-wavelength systems can be useful: the practitioner has more treatment options available rather than having to use one wavelength for every patient.

Hair-removal treatment deliberately creates heat within the intended target. At the same time, unwanted heating of the epidermis needs to be managed.

Contact cooling can help remove heat from the surface of the skin and support treatment comfort.

Ultra Silk Plus uses a sapphire contact window with thermoelectric — TEC — cooling, supported by water and air circulation. Its contact surface is automatically temperature regulated during use.

Cooling should never be used as justification for excessive settings. It works alongside — rather than replacing — appropriate patient selection, parameter choice and professional technique.

Two Diode machines can advertise the same wavelengths while feeling quite different in clinical use.

Spot size affects the area covered by each application. Larger treatment windows can help with efficient coverage of areas such as backs or legs, while smaller areas still need sufficient treatment control.

Pulse width changes how quickly the selected energy is delivered. This gives practitioners another variable when adapting treatment to different hair and skin characteristics.

Ultra Silk Plus uses a 12 × 20mm Diode treatment window and provides a 10–400ms Diode pulse-width range.

Those figures are useful, but they should be considered alongside cooling, wavelength selection, fluence and practitioner technique rather than viewed in isolation.

Importantly, the AI system is a setting-support tool rather than a replacement for professional judgement.

Practitioner assessment, contraindications, skin phototyping, appropriate test patching and final parameter choice remain the responsibility of the trained operator.

A dedicated Diode system makes most sense where long-term hair reduction is going to be an important treatment category.

It should not automatically be described as the right first machine for every clinic. A business focused primarily on skin rejuvenation may use an IPL or resurfacing technology more often. A clinic focused heavily on hair reduction may prioritise Diode.

A clinic wanting both hair reduction and a broader light/laser menu may prefer a multi-technology platform.

The ability to alter wavelength, pulse duration, fluence and other parameters makes proper training central to professional Diode Laser use.

Pure Tone professional equipment training is CPD certified and nurse-led by qualified nurses.

Training can take place at the Pure Tone Aesthetics Training Academy in Cheadle, or our nurses can travel to the purchasing clinic and train the team there.

Pure Tone professional equipment is personally delivered and installed, with ongoing clinical and technical support available after training.