- replace windows on acav chamber by ar-coated windows
- find source of reflection in cavity - my guess it is the dirty coating - the spot size is about 1cm, so it can't be a pure reflection from any of the other surfaces as the beam is too large. The concave mirror surface acts like a convex surface in reflection and intensity increases when cavity is locked.
- clean mirrors of current cavity, replace mirrors or replace entire cavity
- clean all optics on table - entirely and double check with real bright white-light source
- make acav RFPD resonant or wait for new RF photodiodes to be ready
- tune PMC RFPD to 21.5MHz (easy)
- add AOM in RCAV path (doesn't help right now to lower phase noise or increase range of PLL)
- lower beam height for beat setup in transmission
- replace RFPD for pll by larger size PD
- add notch for PMC
- replace current FSS stuff by adv LIGO version
- check max tuning range for wenzel vco
- add perl script for temp feedback to acav to keep beat constant (long term stability)
- replace LO for ACAV and RCAV by real sinewave (wenzel+amplifier)
- change gain in RFPDs for 1mW max light
- measure seismic on table
- float table to see what happens (75PSI are not enough, tested today)
- ...
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