The idea was to check whether the diode ageing could triggers the beam alignment drift.

# Sensitivity of beam alignement with diode power

plot 1 says that for dP/P = 4% we notice a beam drift by 40 mV on AMP_QD_NF_H

Rem.: the coupling RIN to offset of AMP_QD_NF_H (0.1 V) would lead to only 4 mV, therefore the main contribution is indeed related to beam drift

plot 2 says that since the beg of O3 the neoVAN power has reduced by 1.5 W, that is ~ 1.6 % (upper blue line), in the meantime the AMP_QD_NF_H has drifted by 12.5 / 50 = 0.25 V (*), green line

(*) I used a factor 50 scaling while plotting  AMP_QD_DF_H (for display convenience)

Conclusion

The long term trend of the alignment drift is much larger with what would have been expected from the direct calibration made in 46653   

Therefore the diode ageing is not the main contributor ot the beam drift