The phrase "ultraviolet wavelengths" refers to a type of light that is not visible to the human eye. It is a high-frequency, short wavelength of light that falls just beyond the violet end of the color spectrum. Full definition
Watching the sun in ultraviolet wavelengths of light from space — above our UV light - blocking atmosphere — reveals constant activity, including bursts of light, particles, and magnetic fields. (sciencedaily.com)
The treated fibers could be used to transmit a wide range of infrared, visible and ultraviolet wavelengths of light, according to the research team. (sciencedaily.com)
A series of observations in ultraviolet wavelengths planned for next year may help scientists distinguish between these widely disparate explanations. (sciencemag.org)