As we reported before, demodulation phase for QPD1 changes day by day, and pitch and yaw coupling in WFS1 is not good. We guess that this may be because QPD1 is at the waist position. QPD1 is sensitive to gouy phase change and astigmatism.

As we reported before, optimal demodulation phase for QPD1 changes day by day and pitch and yaw coupling in WFS1 is not good. We guess that this may be because QPD1 is at the waist position. QPD1 is sensitive to gouy phase change and astigmatism.

 

We moved QPD positions to have +- 45 deg gouy phase. Yuhang will report the new optical design for WFS.

 

First we optimized DDS demodulation phase for WFS2 by looking at 12Hz line in INPUT PIT. The optimal DDS demodulation phase for WFS2 is 135 deg.

 

Then we optimized DGS demodulation phase for WFS1. The optimal DGS demodulation phase for WFS1 is 157.5 deg.

 

We measured sensing matrix. For WFS1, pitch and yaw coupling for END YAW is much better while others are more or less similar with previous configuration. For WFS2, only INPUT PIT is good and others are worse than previous configuration.

 

	INPUT PIT	INPUT YAW	END PIT	END YAW
WFS1_I_PIT	0.41	0.06	0.2	0.02
WFS1_I_YAW	0.1	0.48	0.13	0.19
WFS2_I_PIT	0.21	0.05	0.23	0.09
WFS2_I_YAW	0.01	0.18	0.1	0.25

 

Since there is still pitch and yaw coupling in WFS1, we rotated WFS1 pitch and yaw by 10 deg to minimize 11 Hz BS pitch peak in WFS1. Then we measured sensing matrix again.

 

	INPUT PIT	INPUT YAW	END PIT	END YAW
WFS1_I_PIT	0.37	0.14	0.23	0.03
WFS1_I_YAW	0.03	0.45	0.07	0.17
WFS2_I_PIT	0.21	0.05	0.23	0.09
WFS2_I_YAW	0.01	0.18	0.1	0.25

 

Rotation of WFS1 pitch and yaw makes INPUT/END PIT better and makes INPUT/END YAW a bit worse.