Befor mesuring the Sapphire sample I made once again the calibration of the bulk reference sample (Schott glass#12 Abs=116%/cm) with low power 55mW and I found a calibrtion factor R=0.43W-1 (about 10% smaller than usually).

I measure the absorption of the Sapphire sample.

Pump power = 9.5W (maximum avaulable)

The scan along the Z axis Figure1 and Figure2 shows that the absorption value is 18 ppm/cm. The value has to be taken at the lowest inner point which is at Z=6mm in this case.

Then I moved the sample to that Z position and I made a map of 20x20mm with a resolution of 2x2mm.

I made it twice to check the repeatability (Figure3 and Figure4 ), and then I plot the difference Figure5 which is about the noise level: 1ppm/cm,

I made a higher resolution map  1x1mm (See Figure6).