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Message ID: 1861     Entry time: Fri Aug 7 17:46:21 2009
Author: Zach 
Type: Update 
Category: Cameras 
Subject: The phase camera is sort of working 

Shown below are the plots of the amplitude and phase of the Mephisto laser light modulated with a chopper as a square wave at about 1 kHz.  The color bar for the phase should run from -pi to pi, and it does when I don't accidently comment out the color bar function.  Anyway, the phase is consistently pi/4 or pi/4 plus or minus pi.  Usually all three of these phases occur within the same image, as shown below.  Also, the amplitude is a factor of two or so higher than it should be where this phase jump occurs.  I think these problems are associated with the nature of the square wave.  However, there is a software bug that appears to be independent of the input data: there is a rounding error that causes the amplitude to jump to infinity at certain points.  This happened for only a dozen or so pixels so I deleted them from the amplitude plot shown below.  I am currently working on a more robust code that will use the Newton-Raphson method for nonlinear systems of equations. 

Attachment 1: ampAv.png  104 kB  | Hide | Hide all
ampAv.png
Attachment 2: phaseAv.png  189 kB  | Hide | Hide all
phaseAv.png
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