A very unfortunate possible explanation of the calibration problem could be a double mistake on the true absorption value bulk reference sample from the company. The Schott glass #12.
So I measured it again with a laser and a power meter.
Incident power         =   76.7 mW
Transmitted power  =    42.5 mW    55%
Reflected power      =   5.5 mW       7.2%

Therefore the absorbed portion is  37.8%
The absorption rate 37.8% / 0.36cm = 105%/cm

This confirms the measurement done 3 years ago by Tatsumi-san elog entry 88