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Entry  Mon Jul 12 15:49:56 2010, nancy, Update, SUS, Characterisation of the QPD fullyaw.jpgyaw_linear.jpgfullpitch.jpgpitch_linear.jpg
    Reply  Mon Jul 12 17:05:30 2010, nancy, Update, SUS, Characterisation of the QPD plot.pngplot.png
Message ID: 3197     Entry time: Mon Jul 12 15:49:56 2010     Reply to this: 3198
Author: nancy 
Type: Update 
Category: SUS 
Subject: Characterisation of the QPD 

I and koji setup the measurement of the QPD response to the pitch and yaw displacements of the beam spot.

We did this using a 100mW 1064nm laser. Its power was attenuated to ~ 1.9mW, and the spot size at the QPD position was 6000-7000 um .

The QPD was put on a translation stage, using which, the center of teh QPD wrt the beam spot could be moved in pitch and yaw.

Following are the measurements :

For yaw


The slope of teh linear region is -8356 /inch


 For pitch


The slope of the linear region in this is 9085/inch




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