This is a report of AZTEC #3 birefringence measurements where each map had for parameters : X_center = 400.735 mm, Y_center = 122.105 mm, Z_center = 70.275 mm, with 70 mm radius.

Birefringence characterization :

Figures 1 to 6 are the usual polarization measurements, 7 to 9 summarize informations about the stress tensors and delta n and theta distributions.

The sample seems quite uniform and is now a good candidate for KAGRA (it also had quite low absorption).

c axis orientation estimation :

In figure 10, I tried to compute from the mean output polarization the orientation of the sample c axis.

The mean output polarization is fitted by a sine square as a function of the input polarization where errorbars represent 1 sigma uncertainty.

From this fit, it seems that if we inject 50.23 deg input polarization we should have the same at the ouput.

In order to constrain a bit more the fit I am now doing a measurement with p polarization at the input and then will start the measurement at the polarization angle that should be conserved throughout the sample.