Diode, Alexandrite or Nd:YAG? Laser Hair Removal and Skin Phototypes

Choosing a laser hair-removal technology is one of the most important decisions for a clinic. Each of the three main technologies – alexandrite (755 nm), diode (usually 808–810 nm) and Nd:YAG (1064 nm) – has strengths and limitations that stem from the physics of light absorption by melanin.

How it works: selective photothermolysis

Laser light is absorbed by melanin in the hair shaft and converted into heat, which damages the follicle. However, the same chromophore is present in the epidermis – the darker the skin, the higher the risk of burns. This is why matching the wavelength and parameters to the skin type is essential.

Alexandrite laser 755 nm

• the highest melanin absorption of the three technologies;
• very effective on light, fine hair;
• recommended for skin types I–III, IV with caution;
• higher risk of pigmentation changes and burns on dark and tanned skin;
• usually higher purchase and running costs (flash lamps, alexandrite rod).

Diode laser 808 nm

• a versatile balance between efficacy and safety;
• skin types I–IV, and V with appropriate parameters and cooling;
• high repetition rates enable fast in-motion treatments;
• low running costs and long module lifetime;
• multi-wavelength devices combine 808 nm with 755 and 1064 nm.

Nd:YAG laser 1064 nm

• the deepest penetration and the lowest absorption in epidermal melanin;
• the safest choice for skin types V–VI and tanned skin;
• lower efficacy on light and fine hair;
• treatment can be more painful – requires good cooling.

Matching to skin types – at a glance

• skin type I–II: 755 nm or 808 nm (or a mix with a predominance of 755 nm);
• skin type III: 808 nm, or 755 nm with cautious parameters;
• skin type IV: 808 nm or an 808/1064 nm mix;
• skin type V–VI: 1064 nm or a mix with a predominance of 1064 nm, longer pulses, lower fluences and efficient cooling.

Grey, red and very light hair (with little eumelanin) remains a challenge for every laser technology – patients should be informed honestly about limited efficacy.

Safety in practice

Whatever the technology: take a medical history (photosensitising drugs, tanning, pregnancy), perform a test patch, record parameters in the treatment chart and use protective eyewear for staff and patient. These topics are covered in detail in the course "Advanced User of Diode and Hybrid Lasers".

Summary

For most clinics serving a diverse patient base, a multi-wavelength diode laser (755/808/1064 nm) is the most versatile choice. Alexandrite suits clinics with predominantly fair-skinned patients, and Nd:YAG those where darker skin types prevail.