How to Choose the Wavelength for an IPL Device

When clients come to talk OEM partnerships, wavelength is the question that can’t be avoided. And it’s the right question to ask, because wavelength decides what the device mainly absorbs light into, and it decides the safety profile. From the lamp to the filter, the entire design of a device revolves around wavelength.

Filters block the short wavelengths first

An IPL lamp emits a whole broad spectrum — it has every wavelength. Short wavelengths carry high energy and are most readily absorbed by the epidermis; let them through raw and light-skinned people get burned. That’s why the device needs cutoff filters. Common IPL cutoff filters on the market cut off between 550 and 950 nanometers. With that band blocked, light skin is protected and the follicle still receives enough energy.

Broad spectrum versus narrow band, two routes

Broad-spectrum IPL can take care of several targets at once — melanin in the hair shaft, hemoglobin in vascular lesions, collagen in the dermis — so hair removal, vascular issues, and skin rejuvenation can all be done with one device. Narrow-band devices or lasers lock onto a single target. They’re more targeted, and hair removal results may be better, but there’s less they can do.

Hair thickness and skin tone both need to be matched

Thick, dark hairs absorb more light and respond best to IPL. Thin, light hairs absorb less — either you turn up the parameters more aggressively, or you switch to a dedicated technology like diode lasers. Skin tone matters even more. Dark skin — Fitzpatrick types IV to VI — carries more melanin in the epidermis, so it needs longer wavelengths and lower energy density to avoid damaging the epidermis. This skin typing system was proposed by dermatologist Thomas Fitzpatrick, who published his systematic treatment in Archives of Dermatology in 1988, dividing skin into types I to VI by sun reaction — the industry still uses it to set parameters today.

Getting a product out has to clear two gates

The first gate is validating on every skin tone the device claims to serve — Fitzpatrick I to IV at standard settings, Type V at the lowest energy level and only after a patch test — confirming the wavelength and energy settings are safe for each. The second is pairing it with real-time skin tone detection: when skin color exceeds what the current wavelength can safely handle, energy automatically drops — or the device simply refuses to fire. Only after both gates can a device claim to work on real populations.

There’s no single standard answer for wavelength. Broad and narrow each have their uses — the key is thinking through exactly who this device is supposed to work for.