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Entry  Wed Nov 18 22:26:33 2015, yutaro, Update, Optical Levers, Calibration of oplevs for ITMY/ETMY calib_etmypit2.pdfcalib_etmyyaw2.pdfcalib_itmypit2.pdfcalib_itmyyaw2.pdfcalib_oplev.zip
    Reply  Wed Nov 18 23:40:01 2015, rana, Update, Optical Levers, Calibration of oplevs for ITMY/ETMY 
       Reply  Thu Nov 19 16:06:54 2015, yutaro, Update, Optical Levers, Calibration of oplevs for ITMY/ETMY 
    Reply  Tue Dec 1 11:26:23 2015, yutaro, Update, Optical Levers, Calibration of oplevs for ITMX/ETMX ep_l.pdfey_l.pdfip_l.pdfiy_l.pdf
       Reply  Thu Dec 3 06:15:38 2015, rana, Update, Optical Levers, Calibration of oplevs for ITMX/ETMX 
          Reply  Thu Dec 3 10:05:07 2015, yutaro, Update, Optical Levers, Calibration of oplevs for ITMX/ETMX 
       Reply  Fri Dec 11 16:16:36 2015, yutaro, Update, Optical Levers, Calibration of oplevs for ITMX/ETMX 
          Reply  Mon Dec 14 23:49:03 2015, ericq, Update, Optical Levers, Calibration of oplevs for ITMX/ETMX 
Message ID: 11785     Entry time: Wed Nov 18 22:26:33 2015     Reply to this: 11787   11831
Author: yutaro 
Type: Update 
Category: Optical Levers 
Subject: Calibration of oplevs for ITMY/ETMY 

Based on elog 1403, I calibrated the oplevs for ITMY/ETMY.

Summary of this method is following:

We lock an arm, and slightly misalign one mirror of the arm. Then, the transmission of the arm starts to decrease quadratically as the misalign angle of the mirror changes. Here, how much the transmission decreases in terms of the misalign angle is determined by geometry of optics, so we can see how much the angle really changes from this quadratic curve.

 

RESULTS  

These are the relationship between misalign angles measured by oplev (the units are based on the calibration for now) and transmission power.

(I updated following figures on Nov 19 2015. You can find the figures I attached once here in the zipped folder attached.) 

 

 

According to this measurement, ratio of the calibration factor derived with this measurement (NEW) and the calibration factor for now (OLD), i.e. NEW/OLD was:  

ETMY_PIT: 5.0265  --->> 5.3922 (without an outlier; the outlier I removed is shown in the figure in zipped folder attached.)

ETMY_YAW: 4.6205

ITMY_PIT: 1.5010

ITMY_YAW: 1.2970

This results show that calibration of oplevs for ITMY is kind of OK, but that for ETMY is so BAD and the calibration factors should be updated.

 

NOTE

The calibration factors of the oplevs for ETMY/ITMY are   NOT UPDATED YET.  I updated on Dec 11, 2015

If these results are reliable, I will update them tomorrow.   

Attachment 1: calib_etmypit2.pdf  42 kB  Uploaded Thu Nov 19 14:50:32 2015  | Hide | Hide all
calib_etmypit2.pdf
Attachment 2: calib_etmyyaw2.pdf  44 kB  Uploaded Thu Nov 19 14:50:54 2015  | Hide | Hide all
calib_etmyyaw2.pdf
Attachment 3: calib_itmypit2.pdf  43 kB  Uploaded Thu Nov 19 14:51:10 2015  | Hide | Hide all
calib_itmypit2.pdf
Attachment 4: calib_itmyyaw2.pdf  43 kB  Uploaded Thu Nov 19 14:51:36 2015  | Hide | Hide all
calib_itmyyaw2.pdf
Attachment 5: calib_oplev.zip  227 kB  Uploaded Thu Nov 19 14:54:07 2015
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