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| == List of FSS Related Electronics Schematics == | == List of PMC Related Electronics Schematics == |
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---- == New PMC Base Riser to convert 3" heigh PMC to 4" height == attachment:PMC_riser.eprt |
The Pre Mode Cleaner is triangular ring cavity mounted on a mostly monolithic fused silica spacer.
Its purpose is mainly to passively filter out laser noise above ~1 MHz. This is needed because none of our active servos do anything good at such high frequencies.
A secondary purpose is that it also spatially filters the light which comes out of the MOPA.
In reality, the PMC is mostly superfluous at the 40m. The raw laser noise falls off like 1/f^2 above the ~600 kHz relaxation oscillation of the NPRO and none of our demodulation frequencies are below 30 MHz. We would need to detect ~300 mA of photocurrent in order to be able to detect the NPRO's RFAM.
Table of PMC Parameters
Parameter |
Value |
Reference |
Pole Frequency |
800 kHz |
|
Finesse |
800 |
|
Input Mirror T |
0.3 % |
calc |
Output Mirror T |
0.3 % |
calc |
Back Mirror T |
100 ppm ?? |
calc |
Free Spectral Range |
713 MHz |
PSL FDD |
Length |
205 mm |
PSL FDD |
Material |
Fused Silica |
PSL FDD |
PZT Calibration |
10.4 nm/V |
List of PMC Related Electronics Schematics
- 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)
New PMC Base Riser to convert 3" heigh PMC to 4" height
attachment:PMC_riser.eprt
attachment:premodecleaner.jpg
See Also
[http://www.ligo.caltech.edu/docs/T/T010145-00.pdf PSL Commissioning Report]
[http://www.ligo.caltech.edu/docs/T/T990025-00.pdf PSL Final Design Document (iLIGO)]