A UV wavelength describes how long the wavelength of a certain range of light is, and is measured in either nanometers (nm) or electron volts (eV). Humans are unable to see UV light. UV wavelength is a type of electromagnetic radiation that has a shorter wavelength than visible light. The name UV wavelength is short for ultraviolet wavelength. This name comes from the fact that the color with the highest frequency humans can still see is violet, and ultraviolet light is above that, thus making it undetectable to the human eye.
The most commonly known type of UV light comes from the sun and black lights found in stores. When the UV wavelength hits certain materials, it causes a chemical reaction and they appear to glow. UV light can be both helpful and harmful to humans. While it can provide the vitamin D people need to be healthy, it can also cause painful sunburns. These are not only unpleasant, but can eventually lead to skin cancer.
There are several ways to detect UV light. UV light covers a wide spectrum, from 10 nm to 400 nm, and there are different instruments for detecting different parts of the spectrum. Near UV wavelength detectors are devices that can pick up UV wavelengths in the 200 nm to 400 nm range. Instruments like the photodiode convert the light into a current that can be detected. UV light can then be expressed in electric volts from 3eV up to 124 eV.
Other instruments, such as the photocathode, produce electron emissions when hit with light. They will react to the UV light and can then be examined to determine the amount of light hitting the instrument. Yet another type of detector, known as a vacuum UV detector, can block out other light sources to try and only pick up UV light.
Problems do occur with each of these instruments. While they can try to reduce the amount of visible light detected by the instrument, they can easily be contaminated by other light sources. The devices pick up all light, not just UV light. This makes it more challenging to determine how much of the light is UV light and how much is natural or some other type.