Today I tried to tweak the input pump power and did several long Z scan to find the 2 surfaces of the sample.

Because it did not succeed at first, I reinstalled the bulk reference sample and got R_bulk = 0.8342 cm/W

Finally, by taking 10 averages and mean I could see the surfaces and started the measurement at Z_center = 62.75 mm

Using the value of this long Z scan the absorption is consistent with the previous measurement :

AC ~ 1.5e-4V

DC~4V

Ptrans = 6.290W

Pinc = 7.315W

gives absorption ~ 22 ppm/cm

Measurement is on-going with 0.5mm step size and 30 mm radius.

Do not touch the sample this week !