brightness

of a laser dye
https://doi.org/10.1351/goldbook.BT07338
Product of the fluorescence quantum yield (Φf) of a dye and the molar decadic absorption coefficient at the excitation wavelength, ε(λ), i.e., Φf ε(λ).
Source:
PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 310 [Terms] [Paper]