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| If SLOWDC isn't changing, try changing RC transmission level to 6 for ~10 seconds, then slide back. | The FSS has a [[/SLOW PID servo]] which offloads the FAST (PZT) path by feeding back to the NPRO's SLOW input. The FAST has a rough calibration of 5 MHz/V while the SLOW is more like 5000 MHz/V. It has a ~0.1 Hz pole and so that's why its called ''SLOW''. ---- == List of FSS Related Electronics Schematics == |
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| Sometimes the slow loop code gets bogged down, so moving the transmission level above the ref. cavity transmission level will break the code out of its frozen state since it will think that the mode cleaner isn't locked. | * TT FSS Box (by Schwinberg, Myers, and Savage, based on the Rich Abbott original) * TT ISS Box (by Flavio Nocera w/ lots of prodding from Rana) * [http://www.ligo.caltech.edu/docs/D/D980401-B1.pdf VCO Driver Box] (R. Abbott) * FSS RFPD (old LSC kind by Dale Ouimette) |
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| * PMC 35.5 MHz Frequency Reference Card (R. Abbott) * PMC Servo (by Karwoski, based on the R. Abbott original - modified by Rana/Jenne based on the Hartmut mods) * PMC RFPD (old LSC kind by Dale Ouimette) * Variac on the HEPA (D. Busby's handiwork) |
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---- == References == * [http://www.ligo.caltech.edu/docs/P/P960008-10.pdf P960008-10]: Improved Multistage Wide Band Laser Frequency Stabilization, by Seiji Kawamura, Alex Abramovici, Mike Zucker (1996). |
The FSS stabilizes the fluctuations in the laser frequency by comparing it to a quiet Reference Cavity. The light is picked off just before it goes into the Pre Mode Cleaner, sent through a EOM and the frequency shifting AOM and then into the RC.
The FSS actuates on the NPRO Piezo (called the FAST path) and on a phase correcting Pockels cell (which is faster than the FAST path).
To lock:
Run the FSSAutolock script from the C1PSL_FSS screen (under the yellow ! button).
The FSS has a /SLOW PID servo which offloads the FAST (PZT) path by feeding back to the NPRO's SLOW input. The FAST has a rough calibration of 5 MHz/V while the SLOW is more like 5000 MHz/V. It has a ~0.1 Hz pole and so that's why its called SLOW.
List of FSS Related Electronics Schematics
- TT FSS Box (by Schwinberg, Myers, and Savage, based on the Rich Abbott original)
- TT ISS Box (by Flavio Nocera w/ lots of prodding from Rana)
[http://www.ligo.caltech.edu/docs/D/D980401-B1.pdf VCO Driver Box] (R. Abbott)
- FSS RFPD (old LSC kind by Dale Ouimette)
- PMC 35.5 MHz Frequency Reference Card (R. Abbott)
- PMC Servo (by Karwoski, based on the R. Abbott original - modified by Rana/Jenne based on the Hartmut mods)
- PMC RFPD (old LSC kind by Dale Ouimette)
- Variac on the HEPA (D. Busby's handiwork)
See also PSL.
attachment:C1PSL_FSS.png
References
[http://www.ligo.caltech.edu/docs/P/P960008-10.pdf P960008-10]: Improved Multistage Wide Band Laser Frequency Stabilization, by Seiji Kawamura, Alex Abramovici, Mike Zucker (1996).