We have changed the offsets of the SDB1 quadrants in order to have, during the lock acquisition with SR aligned, the SDB1 bench aligned in the same position as when the SDB1 dither control is engaged in Low Noise 2.

Based on the attached figure, we have found that the horizontal offset needed to be decreased by -200 (from -150 to -350) and the vertical offset needed to be increased by +100 (from 250 to 350).

Consequently we have set the following new offsets values in the SDB1_Quadrants configuration file :

ACL_CONST_CH        B5_QD2_H_offset     "um"    30    LOOP_FREQ    -350
ACL_CONST_CH        B5_QD2_V_offset     "um"    30    LOOP_FREQ    350

The SDB1_Quadrants process needs to be reloaded at the next relock in order to apply the new offsets values.