I attached to this entry several results extracted from measurements with incident polarizations 90 deg (ie s-pol), 60 deg, 45 deg and 30 deg. They are made based on a python code kindly shared by Simon.
It seems this sample is more uniform than the SHINKOSHA #7.
The s0 component is far smaller while the s1 component is larger. A possible explanation could be (from MIR meeting discussion) that the birefringence appearing here is not due to stress but to the crystal axis orientation with respect to the pump beam optical axis.
The delta n distribution seems to be quite identical for all incident polarizations and the offset might be due to the cutting angle of this sample.
A possible explanation for the offset on the theta distribution for incident polarization of 30 deg could be explain by having rotating the incident polarization by more than 90 deg.
Indeed, the HWP software now is stuck at 15 deg whatever the polarization...
I started again this 30 deg incident polarization while only decreasing the value of the HWP angle.
new measurement with 30 deg polarization finished.
The results (especially of the theta distribution) seems to agree with our hypothesis that the previous measurement with input polarization 30 deg was something like 30+90 deg.