I can't find a reference that explains what, for example, OD600 = 0.1 means.
For example, Wikipedia states
OD600 is an abbreviation indicating the absorbance, or optical density, of a sample measured at a wavelength of 600 nm.
In other words, the OD600 value reports (a function of) what percent of light goes through a sample. But that depends on the thickness of the sample. More light will go through 1 millimeter of fluid than through 1 meter of the same fluid. So what is the thickness of the sample involved when reporting OD600? Or is the OD600 independent of that, so that it actually has units that people simply omit? In that case, what are the units? What is a precise physical interpretation of what is meant by the measurement OD600 = 0.1?
Suppose OD600 = 0.1 for some sample. I shine 1 mW of 600nm laser light through a 1 cm path length of the sample. What is the transmitted power?