Fresnel (unit)
The Fresnel ( unit symbol : fresnel) was a frequency unit proposed by France in 1969 but not accepted internationally , named after the French physicist Augustin Jean Fresnel .
1 fresnel = 10 12 Hertz (Hz) = 1 Terahertz (THz)
source
Peter Kurzweil: The Vieweg unit lexicon. Vieweg, Braunschweig / Wiesbaden 2000, ISBN 978-3528069872 .