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Message ID: 9590     Entry time: Fri Jan 31 19:29:36 2014
Author: Gabriele 
Type: Summary 
Category: LSC 
Subject: PRC and SRC lengths 

 Today we measured the missing distance to reconstruct SRC length.

I also changed the way the mirror positions are reconstructed. In total for PRC and SRC we took 13 measurements between different points. The script runs a global fit to these distances based on eight distances and four incidence angles on PR2, PR2, SR2 and SR3. The optimal values are those that minimize the maximum error of the 13 measurements with respect to the ones reconstructed on the base of the parameters. The new script is attached (sorry, the code is not the cleanest one I ever wrote...)

The reconstructed distances are:

Reconstructed lengths [mm]:
LX    = 6771
LY    = 6734
LPRC  = 6752
LX-LY = 37
LSX   = 5493
LSY   = 5456
LSRC  = 5474

The angles of incidence of the beam on the mirrors are very close to those coming from the CAD drawing (within 0.15 degrees):

Reconstructed angles [deg]:
aoi PR3 = 41.11 (CAD 41)
aoi PR2 = 1.48  (CAD 1.5)
aoi SR3 = 43.90 (CAD 44)
aoi SR2 = 5.64  (CAD 5.5)

The errors in the measured distances w.r.t. the reconstructed one are all smaller than 1.5 mm. This seems a good check of the global consistency of the measurement and of the reconstruction method.

NOTES: in the reconstruction, the BS is assumed to be exactly at 45 degrees; wedges are not considered.

 

 

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