Wavelengths

I had an interesting query today regarding the penetration of red and near infrared light into the body.

Question:

Does the penetration of red and near infrared light increase as the wavelength increases?

Answer:

Alas, no. The human body isn’t going to make life that easy for us!

Penetration studies have shown that 810 nanometres (written as 810nm) has the best ability to penetrate through the skin and into the body tissues.

There are some wavelengths in the red and near infrared spectrum that hardly penetrate at all, while others are better. 810nm is the best.

810nm is in the near infrared range. Because it is at the very edge of our ability to see, an 810nm light looks very pale.

Visible red 670nm is pretty good, but not as good as 810nm. However, when the 670nm wavelength reaches the cell, it is highly efficient at getting the cell batteries (mitochondria) to recharge and kickstart the cell.

Thanks To Steve Harvey on Unsplash for the great photo from Nottingham.