Angstrom (A0)
From The Glossary of Digital Photography
A unit used to measure very small lengths, such as the diameter of atoms and the spectra of visible light. One Angstrom = 10-10 meters. It was named after Anders Jonas Angstrom (1814-1874), a Swedish physicist who worked with units on the order of 10-10 meters when he developed a chart of the solar radiation spectrum.
