Optimization of the polarization has been made the 03/10/18. Checked in reflection of the cavity in reflection&transmission of a PBS, locked and unlocked. Only with 2nd stage.

Ratio values are reflection of PBS divided by transmission or the opposite.

2 measurement.

First one locked, in transmission of M2 with 2nd stage 0A.Total 89 cm from the big waist (planar mirrors). 2 wedges used.

Second one at input beam with the same power. Datas taken at the same equivalent position than the first one. 3 wedges used.

* Loic has to fix the number of files (3) regarding the number of measurements (2)

* splitted Intensity and phase HASO files

* image for each file

with just intensity, the coupling is 98%, and with phase, x direction coupling is 95%, y direction 97%, so the telescope is good.

Measurments of Finesse with the 2 polarization states, let's call them H (higher) and L (lower): 24500 for the H and 23500 for the L.

We checked the polarization states in transmission of the FP cavity after a PBS. The H was stronger in PBS trans and the L stronger in PBS ref.

We measured the power in reflection of the PBS and added a half WP that we aligned with the PBS polarization. Then, to get the maximum power we had to tilt the half WP of 22° for the H and 18° for the L.

Finally we checked the extinction through half WP and PBS for H and L. 

- For H : max 75 mW min 5 mW. Ratio 6.66%

- For L : max 70 mW min 4 mW. Ratio 5.7%

Right after Koheras : max 3.5 mW min 47 uW. Ratio 1.3%