Understanding Ultraviolet LED Wavelength

What is Ultraviolet Wavelength?

The Sun is a source of the full spectrum of ultraviolet radiation, which is commonly subdivided into UV-A, UV-B, and UV-C. Wavelength, a fundamental descriptor of electromagnetic energy, is the distance between corresponding points of a propagated wave. Typical UV light source emission wavelengths range from ultraviolet (UV-C 100-280nm, UV-B: 280-315nm, UV-A 315-400nm) to visible light (400-700nm) and infrared (700-3000nm). 

UV wavelengths typically are measured in nanometers (nm).  Nanometer, a unit of length, is equal to one billionth of a meter. UV light-emitting diodes (LEDs) have a narrow spectral output centered on a specific wavelength, +/- 15nm, with typical commercial UV LED lamps emitting at 365nm, 385nm, 395nm, or 405nm wavelengths.

The irradiance (W/cm²) produced by UV LED light sources has increased consistently year over year because of advancements in both diode and lamp technology, and now is available at effective outputs higher than those offered by traditional UV curing lamp technologies.  UV LED lamp systems have enough power to conquer a wide range of applications and today are being used commercially to cure inks, coatings and adhesives. Today, UV LED curing lamps at 395nm offer up to 24W/cm² peak irradiance and that number will continue to increase.  Water-cooled systems to manage heat in UV-LED sources now are available and further enable increases in peak irradiance, with UV LED systems available offering 12W/cm² and air-cooled systems offering 8W/cm² peak irradiance at 365nm. The advent of UV LED sources with high peak irradiance at 365nm is a significant advance in the LED industry, as it enables the use of many commonly available commercial photoinitiators in formulations cured with UV LED systems.