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Message ID: 1908     Entry time: Fri Aug 14 23:45:14 2009
Author: Chris 
Type: Update 
Category: General 
Subject: Long Range Readout 

The EUCLID-style Michelson readout is on the SP table now and is aligned.  See image below.  I took several power spectra with the plotter attached to the HP3563 (not sure if there's another way to get the data out) and I'm still waiting to calibrate (since dP/dL isn't constant as it isn't locked, this is taking a bit longer).  When put into XY mode on the oscilliscope (plotting Voltage at PD2 on the x and Voltage at PD3 on the y), a Lissajous figure as in the first plot below.  It's offset and elliptical due to imperfections (noise, dc offset, etc) but can ideally be used to calculate the L_ target mirror movement.  By rotating the first quarter wave plate by ~80.5deg counter-clockwise (fast axis was originally at Pi/8, now at 103deg), I was able to turn the Lissajous figure from an ellipse into a more circular shape, which would ideally allow for us to use a circular approximation (much simpler) in our displacement calculations.

Attachment 1: Table_Setup.png  2.300 MB  | Hide | Hide all | Show all
Attachment 2: Ellipse.jpg  118 kB  | Hide | Hide all | Show all
Attachment 3: Circle.jpg  136 kB  Uploaded Sat Aug 15 00:45:35 2009  | Show | Hide all | Show all
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