pick-off beams in the central interferometer of advanced virgo
DESCRIPTION
Pick-off beams in the central Interferometer of Advanced Virgo. Stefan Hild January 2009. Creation points of Pick-off beam. All Anti-reflex coatings potentially cause secondary beams. Pick-off beams have about 10 to 20mW (6ppm x 2.7kW) - PowerPoint PPT PresentationTRANSCRIPT
Stefan Hild
January 2009
Pick-off beams in the central Interferometer of Advanced Virgo
S. Hild January 2009 Slide 2
Creation points of Pick-off beam
All Anti-reflex coatings potentially cause secondary beams.
Pick-off beams have about 10 to 20mW (6ppm x 2.7kW)
Pick-off beams are of similar size as the main IFO beam (LARGE!)
These 15 (18) beams should either be detected or properly dumped
3 beams from PRC(+3 beams from SRC) 2 beams
4 beams
2 beams
4 beams
S. Hild January 2009 Slide 3
Why more pick-off beams than in Virgo?
Pick-off port Initial Virgo Advanced Virgo
Input mirror AR Etalon 2 beams each
Compensation plates No CPs 4 beams each
BSAR PRC 1x used (B5)
2x unused (not dumped)
3 beams
BSAR SRC 3x unused
(not dumped)
(3 beams ?)
S. Hild January 2009 Slide 4
Input mirror AR coating
Can an Etalon (A) be control-led well enough with the CP so close by?
C should be avoided, because of scattered light.
D: one beam is strongly divergent.
S. Hild January 2009 Slide 5
Pick-offs from the CPs
CP is probably primary pick-off for ISC.
For ASC it might be important to have no overlapping beams (distributing the secondary beams in 3D).
Divergence of CP pick-offs depends on IM backsurface (lens or not).
If we get the CP pick-offs to work for ISC, we can probably dump the B5 beam.
S. Hild January 2009 Slide 6
Secondary reflections from BS 3 beams from within PRC needs
to be dealt with for AdV.
What to do about the 3 beams from within the SRC (in contrast they are not differential)?
Do we need B5 or can it be dumped?
Currently not dumped beam