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| = Tuning FP modal frequencies using a thermal phase correction feedback system = | = Tuning FP modal frequencies using a thermal phase error correction feedback system = |
Tuning FP modal frequencies using a thermal phase error correction feedback system
Goal
To compensate for imperfections that arise due to optical inhomogeneities in the arm cavity mirrors by designing and implementing a thermal compensation system.
The lessons learned from this exercise will help in designing/implementing a similar kind of system for the folding mirrors in the recycling cavities.
Fact-finding
- What are the ideal cavity parameters? (a reference to compare the different heating models)
- Sources of inhomogeneity : (i) Deviation from mirror specs (ii) Thermal effects due to circulating arm cavity power (iii) Surface roughness
- Increase or decrease RoC of the ETM to correct for inhomogeneities (choose between the ring-heater design and the VIRGO chrocc design)
- Desired tuneable range and achievable range
- Effect of heating at 1064nm and 532nm
- Best heating profile
- Practical/hardware limitations in implementing