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Warming up for the OSD workshop. S.Hild and A.Freise January 2009. Reference layout of NDRC. See talk by Massimo. QUESTION => How much astigmatism is introduced by: Divergent beam (strong lens in input mirrors) passing BS and CP? Off axis telescopes of PRM1-3 and SRM1-3? - PowerPoint PPT Presentation
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S.Hild and A.Freise
January 2009
Warming up for the OSD workshop
S. Hild January 2009 Slide 2
Reference layout of NDRC
QUESTION => How much astigmatism is introduced by: Divergent beam (strong lens
in input mirrors) passing BS and CP?
Off axis telescopes of PRM1-3 and SRM1-3?
QUESTION => How much astigmatism driven loss we can accept in PRC and SRC?
QUESTION => How to suspend PRM1, PRM3, SRM1 and SRM3?
See talk by Matteo
See talk by Massimo
S. Hild January 2009 Slide 3
NDRC with lenses moved to the BS In case the astigmatism
from the BS and the CPs is too strong…
IDEA: Move lenses out of input mirrors and put them close to the BS (out of IFO arms).
QUESTION => How to suspend the lenses in the BS tank?
QUESTION => Can we buy such lenses (quality, size, …)
QUESTION => Does the Non-Degeneracy still work in this setup?
See talk by Roberto/ Giovanni
S. Hild January 2009 Slide 4
Long NDRC without lenses In case we want/need a design without
any lenses we have to make the recycling cavities as long as possible…
IDEA (from Julien): Move PRM2 into north input tank, passing the beam underneath BS and suspend PRM2 from IM reference mass.
QUESTION => Does non-degeneracy still work?
QUESTION => Is it possible to suspende PRM2 from the reference mass?
QUESTION => Can we fit beams into the vacuum?
QUESTION => Could we fit suspended 35 cm optics onto the injection and detection benches?
See talk by Carlo/Antonio
See talks by Benoit and Eric ?
See slides from Andreas
See talk by Julien
S. Hild January 2009 Slide 5
Pick-off beams
QUESTION => Which pick-off beams are necessary for ISC? BSAR? IM/CP?
Proposed Strategy: all secondary beams (4 beams from each CP, 2 beams from each IM, 3 beams from BS = TOTAL about 15 large beams) are either detected or properly dumped.
S. Hild January 2009 Slide 6
Pick-off beams from IM and CP
QUESTION => Can pick-offs, consisting of several beams, be used for ISC purpose?
QUESTION => Is it possible to deal with divergent pick-off beams (up to about 1m diameter!)
QUESTION => Do we have the space direct pick-offs in 4 different directions (below, above, left and right of main beam)?This plot is only to show effects qualitatively. A proper CAD drawing is required…
S. Hild January 2009 Slide 7
Eliminating pick-offs from IM and CP?
We could get rid of the pick-off beams from the IM-AR by making them etalons: QUESTION: Are the etalons required for reducing noise couplings? QUESTION: Would it be possible to control an IM etalon?
In principle we could get rid of CP secondary beams by aligning the CPs to the main beam: QUESTION: Any noise problems from additional low finesse Fabry Perot? QUESTION: Is it possible to keep the CPs aligned (refernce mass moves when
actuating on main test masses)?
S. Hild January 2009 Slide 8
Extraction of pick-off from BS-AR Pick-off from BS-AR coating needs to
separated from the main beam before being reflected back into the interferometer from the Signal-Recycling mirror.
IDEA: Extract the BSAR-pickoff close to the beam waist between SRM2 and SRM3 (should work even without BS wedge).
QUESTION => Is it possible install a beam director between SR tower and detection tower?
QUESTION => How to dump the other secondary beams of the BS-AR?
S. Hild January 2009 Slide 9