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Message ID: 769     Entry time: Wed Jul 30 13:52:41 2008
Author: Eric 
Type: Summary 
Category: Cameras 
Subject: Weekly Summary 
I tracked the tendency for ezcaPut to fail and sometimes seg-fault in the camera code to a conflict between the camera API and ezca, either on the 
network level or the thread level.  Since neither are sophisticated enough to provide controls over how they handle these two things, I instead 
separated the call to ezcaPut out into a small, separate script (a stripped down ezcawrite), which the camera code calls at the system level.  This is a 
bit hacky of a solution, but its the only thing that seems to work.

I've developed a transformation based on Euler angles that should be able to take the 4 OSEMs in a picture of the end mirror and use their relative 
positions to determine the angle of the camera to the optic.  This would allow the position data determined by the fitting software to be converted 
from pixels to meaningful lengths, and should aid any servo-ing done on the beams position.  I've yet to actually test if the equations work, though.

The servo code needs to have slew rate limiters and maximums/minimums to protect the mirrors written in to it before it can be tested again, but I 
have no idea what reasonable values for these limits are.

Joe and I recently scanned the PMC by driving C1:PSL-PMC_RAMP with the trianglewave script over a range of -3.5 to -1.25 (around 50 to 150 volts 
to the PZT) and read out C1:PSL-ISS_INMONPD to measure the transmission intensity.  This included slightly under 2 FSRs.  For slow scans (covering 
the range in 150 to 300 s), the peaks were very messy (even with the laser power at 1/6 its normal value), and it was difficult to place where the 
actual peak center occurred.  For faster sans (covering the range in 30 seconds or so), the peaks were very clean and nearly symmetric, but were 
not placed logically (the same peak showed up at two very different values for the PZT voltage in two separate runs).  I don't have time to put 
together graphs of the scans at the moment; I'll have that up sometime this afternoon.
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