It seems that the bulk calibration was overestimated. This is especially apparent when computing its transmission that was 45% instead of the expected 55%.

I performed again the bulk calibration and got :

AC_bulkref = 0.062;
DC_bulkref = 4.14;
P_in = 26.4e-3;
P_t = 13.1e-3;
T_bulkref = P_t/P_in
abs_bulkref = 1.04;
R_bulk = AC_bulkref/(DC_bulkref*sqrt(T_bulkref)*P_in*abs_bulkref) = 0.7743 W/cm

I used this new calibration to compute again the absorption map of the sample (see the 3 attached figures.

In the figure, the absorption is extracted from a fit using 2 normal distributions.

Here I also add the overall mean and standard deviation of each map (ie without any fittting) :