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Entry  Mon Jun 14 22:16:08 2010, Jenne, Update, IOO, Mode scan after Mode Matching Telescope after_MMT.png
    Reply  Tue Jun 15 16:28:32 2010, kiwamu, Update, IOO, Mode Profile after Mode Matching Telescope newIOO_overlap_edit.png
       Reply  Tue Jun 15 19:24:25 2010, rana, Update, IOO, Mode Profile after Mode Matching Telescope 
          Reply  Fri Jun 18 21:45:39 2010, kiwamu, Update, IOO, Mode Profile after Mode Matching Telescope (Round 2) MMT20100618_edit.pngnewIOO_overlap_edit.png
             Reply  Fri Jun 18 22:12:29 2010, Alberto, Update, IOO, Mode Profile after Mode Matching Telescope (Round 2) 
Message ID: 3088     Entry time: Fri Jun 18 21:45:39 2010     In reply to: 3078     Reply to this: 3089
Author: kiwamu 
Type: Update 
Category: IOO 
Subject: Mode Profile after Mode Matching Telescope (Round 2) 

           [Joe, Kiwamu]

The better mode overlap of 99.3% was achieved by moving MMT2 by ~5 cm 

In the past measurement (elog entry #3077) we already succeeded in getting 99.0% mode overlap.

But according to the calculation there still was a room to improve it by moving MMT2 by 10 cm.

Today we moved MMT2 by ~5 cm which is a reasonable amount we could move because of the narrow space in the chamber.

Eventually it successfully got the better mode overlap.

So we eventually finished mode matching of the new IOOs 


     Actually moving of MMT2 was done by flipping the mount without moving the pedestal post as Koji suggested. 

At the same time we also flipped the mirror itself (MMT2) so that the curved surface is correctly facing toward the incident beam.

By this trick, we could move the position of MMT2 without losing precious available space for the other optics in the OMC chamber.

     The attached plot shows the result of the mode measurement after the MMT.

During the fitting I neglected the data at x=27 m and 37 m because the beam at those points were almost clipped by the aperture of the beam scan.

- - Here are the fitting results

w0_v             = 2.81183       +/- 7.793e-03  mm  (0.2772%)

w0_h             = 2.9089        +/- 1.998e-02  mm  (0.687%)

z_v             = 5.35487        +/- 0.2244     m   (4.19%)

z_h             = 1.95931        +/- 0.4151     m   (21.18%)

All the distances are calibrated from the position of MMT2 i.e. the position of MMT2 is set to be zero.

        In order to confirm our results, by using the parameters listed above I performed the same calculation of mode overlaps as that posted on the last entry (see here)

The result is shown in Attachement 2. There is an optimum point at x=62mm.

This value is consistent with what we did because we moved MMT2 by ~5 cm instead of 10 cm. 


Attachment 1: MMT20100618_edit.png  159 kB  | Hide | Hide all
Attachment 2: newIOO_overlap_edit.png  96 kB  | Hide | Hide all
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