Signe I asked around and the people that tried it say it is difficult to interpret the data.
It is pretty straightforward to do a measurement but then the sample is partially translucent and:
- the measured reflected light is weak thus you end up with noisy results
- you don’t know which depth the reflected light comes from
- it matters whether the surface is polished or rough.
The bottom line is that the results are hardly reproducible and so is the interpretation.