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
MC Servo: D040180-C-1 MC_Servo.pdf
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)
VCO Driver Box (R. Abbott)
- FSS RFPD (old LSC kind by Dale Ouimette)
Temperature Control Box (Rich Abbott then changes by Hugh Radkins and Paul Schwinberg) D980400
- Variac on the HEPA (D. Busby's handiwork)
TTFSS interface board diagrams: D040423-A.pdf (Rev A, includes the DIN96 connector), D040423-C.pdf (Rev C), fssxcon.pdf (old xcon schematics)
Test Results for The New TTFSS
Test Plan(Cervantes, Schwinberg, Savage)
See also PSL.
References
P960008-10: Improved Multistage Wide Band Laser Frequency Stabilization, by Seiji Kawamura, Alex Abramovici, Mike Zucker (1996).