I tried to remeasure the coupling from RIN to frequency noise (same setup as in psl:1005). However I have not been able to reproduce the result yet.
The result we got in psl:1005 does not have the same TF shape as we expected from the calculation. The slope is off by 1/f^0.25. So There might be something wrong with the setup, for example bad alignment in EAOM that adds PM to the beam and effect the PDH signal. So in order to verify the problem I redo the measurement with the similar setup. This time, however, when I change the power into ACAV, the measured TF changes as well (this did not happen before), so I'm checking what's wrong with the setup.
Checking plan:Once I can remeasure the TF (ACAV AOM feedback/ ACAV TRANSPD). I want to check
- effect of beam EAOM alignment to the TF
- comparison between TF from (ACAV AOM feedback/ACAV TRANSPD) and (beat signal/ACAV TRANSPD). I tried this already and they are quite similar except some phase shift.
- To verify that the measurement is valid, I'll make sure that the TF is independent of excitation level and power input to ACAV.
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