e606a77c_ng_with_The_Optical_Properties__Notes
[Quantity] Spectral irradiance [Notes] 
commonly measured in W⋅m−2⋅nm−1 or 10−22W⋅m−2⋅Hz−1, known as solar flux unit.[nb 5]
Principles and Guides of Stones Selection Process: Working with The Optical Properties
Notes