• Gautam_Venugopalan

gautam's winter 2019 wishlist

These aren't in any particular order of priority.

1. Make the EY green mode matching better. Currently its ~30%.
2. Make the EY fiber coupling MM better. Currently its ~50%. I recommend just copying the EX layout for both of these - the NPRO mode might be a bit different so the Fiber MM might require slightly different lenses, but the scheme should work i think.
3. What’s up with POX photodiode?
   • I think this isn't actually such a big mystery, there is a ZHL-500-HLN amplifier installed for the RF output of POY11 (but not POX11), which accounts for the imbalance in whitening gain and PDH horn height imbalance.
   • But there is still a discrepancy in the DC mon values, I confirmed both receive ~20uW of power when POX/POY locked, but there is a factor of ~2 discrepancy in the DC value.
4. ASY dither alignment servo
   • Mostly copy the EX servo.
5. IR ASS XARM
   • Since I changed the series resistor on ETMX, the ETMX oscillator amplitudes were not adjusted so the spot centering loop / cavity axis alignment loop relative gains may be mistuned.
6. Get a modern GDS working (NOT ON PIANOSA)
   • See for example elog#15061.
7. Whats up with the drifting input pointing?
   • See for example elog#14467.
8. Install some whitening for the ALS signals - we need an aLIGO whitening unit to be compatible with the aLIGO AA board we're using.
9. Make the connections for the IR ALS power monitor channels (The cable has the wrong gender D9 connector, so maybe we need to order a new cable).
10. Why is POP QPD reporting reduced coherence with the BS seismometer channels, even after re-centering? See elog#15022.
    • This limits the amount of feedforward cancellation we can achieve.
11. Can we improve the arm cavity motion during lock acquisition by implementing SeisFF?