optical absorption depth

symbol: $\mu_{\beta}$, units: $\pu{m}$, $\pu{\upmu\!m}$
https://doi.org/10.1351/goldbook.08650
Depth in a sample at which the intensity of an incident beam is reduced to \(1/\rm{e}\) of its value at the surface of the sample.
Notes:
  1. \(\mu_{\beta}\) is the reciprocal of the linear Napierian absorption coefficient.
  2. SI unit: \(\pu{m}\). Common unit: \(\pu{\upmu\!m}\).
Source:
PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 757 (https://doi.org/10.1515/pac-2019-0203)