April 18, 2018

The Visible Spectrum

To achieve optimal results with ONCE LED lighting systems, the visible spectrum—electromagnetic radiation is light we can see—should first be understood. Light has similar behavior to an ocean wave. As a result, light is characterized by 2 variables: wavelength and intensity. Wavelength is the distance between the two peaks of a wave and intensity refers the number photons hitting given surface area.

The visible spectrum is a small fraction of the many types of electromagnetic radiation that exists. The wavelengths visible to the human eye fall between around 400-700 nm. The longer wavelengths beyond the visible spectrum include infrared radiation, microwave radiation and radio waves. The shorter wavelengths beyond the visible spectrum include, ultraviolet radiation, x-ray and gamma radiation. 

Ultraviolet (UV) light is an electromagnetic radiation not visible to humans. It has shorter wavelengths than visible light but longer wavelengths than X-ray radiation. UV light covers wavelengths from 100 to 400 nm and is divided into three subcategories:

  • UVA (400 – 315 nm) Visible to fish, insects and birds
  • UVB (315 – 280 nm) Used for vitamin D synthesis
  • UVC (280 – 100 nm) Germicidal radiation used to in the BioShift® UV Chamber to strengthen bio-security. Learn about how UV light sterilization works. 

Both UVA and UVB radiation pass through the earth’s atmosphere, reaching the surface, but UVC radiation is mostly absorbed by the ozone layer, never completely reaching land.