What Is the Difference Between 660nm and 850nm Red Light?
What is the difference between 660nm and 850nm light?
Quick answer: 660nm is visible red light. 850nm is near infrared light, which you cannot see. Wavelength is the distance between peaks of a light wave, measured in nanometers (nm). Many home devices include both so that one session uses red and near infrared light together.
660nm (visible red)
- What it is: Light in the red part of the visible spectrum. You can see it as a deep red glow.
- How it behaves: Shorter wavelengths are absorbed closer to the surface of the skin than longer ones.
850nm (near infrared)
- What it is: Light just past the red end of the visible spectrum. It is invisible, and some devices show a faint dim red glow from the LED.
- How it behaves: Longer wavelengths generally travel deeper into tissue than shorter ones.
Why many devices combine both
Devices that include both wavelengths, such as the AWA FX500 and FX300, put red and near infrared light in one session. Whether you want that is a matter of the device you are choosing and the label's instructions. When you compare devices, check the wavelengths listed, the irradiance at your sitting distance and the session time the manufacturer recommends.