Visible spectrum

The visible spectrum is the <a href="/facts/Spectral_band/hw6CxHIS">band</a> of the <a href="/facts/Electromagnetic_spectrum/24LARvFY">electromagnetic spectrum</a> that is <a href="/facts/Visual_perception/g7Tfaq2l">visible</a> to the <a href="/facts/Human_eye/a24ua4fy">human eye</a>. <a href="/facts/Electromagnetic_radiation/Ynx7ujCW">Electromagnetic radiation</a> in this range of <a href="/facts/Wavelength/kcJU0ymz">wavelengths</a> is called <a href="/facts/Visible_light/jeofpMn4">visible light</a> (or simply light).
The optical spectrum is sometimes considered to be the same as the visible spectrum, but some authors define the term more broadly, to include the <a href="/facts/Ultraviolet/kncBUqn5">ultraviolet</a> and <a href="/facts/Infrared/44XdJNcc">infrared</a> parts of the electromagnetic spectrum as well, known collectively as <a href="/facts/Optical_radiation/M618T6rM">optical radiation</a>.
A typical <a href="/facts/Human_eye/a24ua4fy">human eye</a> will respond to wavelengths from about 380 to about 750 <a href="/facts/Nanometers/a98sjHyu">nanometers</a>. In terms of frequency, this corresponds to a band in the vicinity of 400–790 <a href="/facts/Terahertz_(unit)/6Wshj5qm">terahertz</a>. These boundaries are not sharply defined and may vary per individual. Under optimal conditions, these limits of human perception can extend to 310 nm (ultraviolet) and 1100 nm (near infrared).
The spectrum does not contain all the <a href="/facts/Color/XDvW7ESP">colors</a> that the human <a href="/facts/Visual_system/QVcuA27K">visual system</a> can distinguish. <a href="/facts/Excitation_purity/WaePy7Ga">Unsaturated colors</a> such as <a href="/facts/Pink/fHod9nJE">pink</a>, or <a href="/facts/Purple/PVL40QPo">purple</a> variations like <a href="/facts/Magenta/dk2zD4hq">magenta</a>, for example, are absent because they can only be made from a mix of multiple wavelengths. Colors containing only one wavelength are also called pure colors or <a href="/facts/Spectral_color/SG0F8xet">spectral colors</a>.
Visible wavelengths pass largely unattenuated through the <a href="/facts/Earth%27s_atmosphere/FV97Am25">Earth's atmosphere</a> via the "<a href="/facts/Optical_window/ur52Kl8b">optical window</a>" region of the electromagnetic spectrum. An example of this phenomenon is when clean air <a href="/facts/Scattering/nMou7lEH">scatters</a> blue light more than red light, and so the midday sky appears blue (apart from the area around the Sun which appears white because the light is not scattered as much). The optical window is also referred to as the "visible window" because it overlaps the human visible response spectrum. The <a href="/facts/Near_infrared/44XdJNcc">near infrared</a> (NIR) window lies just out of the human vision, as well as the medium wavelength infrared (MWIR) window, and the long-wavelength or far-infrared (LWIR or FIR) window, although other animals may perceive them.

Visible spectrum open-in-new

Visible spectrum