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| == Actual Work in LAB == |
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| * Figure out to get a handle on the oscillator AM measurement, without hacking up the board, if possible. * Make a long LEMO-LEMO cable to go from the OMC crate to the LSC rack for freq. noise coupling measurements. Get TNC connectors from Wilson House. |
* A quadratic correction term for the OMC transmission based DARM signal has been implemented in the LSC code and is labeled OMC QUAD CORR on the C1LA_SET screen. Investigate its use and benefits. == Sit around and think a bit == * the dither-lock signal for the OMC may not have a zero crossing exactly at mid-fringe, depending on HOM content of incoming beam AND (perhaps more importantly) if the RF sidebands impinging on the OMC are unbalanced. The dither signal will find some place which minimizes sensitivy to the combination of these things, not just the nearest resonant mode. Such residual offsets may have implications for the OMC length noise specifications. == modeling == * oscillator phase noise coupling in dc readout -- dominant contribution is likely due to OMC pole/RFsidebandfreq not being zero. |
Actual Work in LAB
- commission input PZT alignment servo using OMC_T in a bright mich to reduce noise in 1-2KHz
- Along those lines, the REFL beam is clearly clipped in the alignment state which the alignment
- scripts leave us in. Investigate--the best way forward is probably to revisit the PSL periscope/mode cleaner alignment and the Faraday isolator.
- The Pentek at ETMY may be glitchy. The coil driver noise is higher there than any of the other
- test masses. It may be the coil driver itself, but suspicion falls on the Pentek.
- A quadratic correction term for the OMC transmission based DARM signal has been implemented in the LSC
- code and is labeled OMC QUAD CORR on the C1LA_SET screen. Investigate its use and benefits.
Sit around and think a bit
- the dither-lock signal for the OMC may not have a zero crossing exactly at mid-fringe, depending on HOM content of
- incoming beam AND (perhaps more importantly) if the RF sidebands impinging on the OMC are unbalanced. The dither signal will find some place which minimizes sensitivy to the combination of these things, not just the nearest resonant mode. Such residual offsets may have implications for the OMC length noise specifications.
modeling
- oscillator phase noise coupling in dc readout -- dominant contribution is likely due to OMC pole/RFsidebandfreq not being zero.