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Entry  Wed Jan 17 23:36:12 2018, johannes, Configuration, General, AS port laser injection PSLbeat.svg.pngASpath.svg.png
    Reply  Wed Apr 18 22:46:23 2018, johannes, Configuration, General, AS port laser injection ASpath.svg.pngpower_out_fluctuation_DC.pngpower_out_fluctuation_AC_zoom.png
       Reply  Thu Apr 19 01:04:00 2018, gautam, Configuration, General, AS port laser injection 
          Reply  Thu Apr 19 20:41:09 2018, Koji, Configuration, General, Aux Laser LD dying? (AS port laser injection) Aux_laser_adj_Pout.pdfAux_laser_RIN.pdf
             Reply  Tue Apr 24 08:36:47 2018, johannes, Configuration, General, Aux Laser LD dying? (AS port laser injection) 
       Reply  Thu May 3 10:40:43 2018, johannes, Configuration, General, AS port laser injection mm_solution_AStable.pngAStable_beampath.pdf
          Reply  Thu May 3 12:10:12 2018, gautam, Configuration, General, AS port laser injection 
          Reply  Wed May 23 00:45:18 2018, johannes, Configuration, General, AS port laser injection faraday_location.pdf
Message ID: 13810     Entry time: Thu May 3 10:40:43 2018     In reply to: 13764     Reply to this: 13811   13881
Author: johannes 
Type: Configuration 
Category: General 
Subject: AS port laser injection 

Instead of trying to couple the fiber output into the interferometer, I'm doing the reverse and maximize the amount of interferometer light going into the fiber. I set up the mode-matching solution shown in attachment #1 and started tweaking the lens positions. Attachment #2 shows the setup on the AS table. After the initial placement I kept moving the lenses in the green arrow directions and got more and more light into the fiber.

When I stopped this work yesterday I measured 86% of the AS port light coming out the other fiber end, and I have not yet reached a turning point with moving the lenses, so it's possible I can tickle out a little more than that.

It occured to me though that I may have been a little hasty with the placement of the mirror that in attachment #2 redirects the beam which would ordinarily go to AS55. For my arm ringdown measurements this doesn't matter, I could actually place it even before the 50/50 beamsplitter that sends light onto AS110 and double the amount of light going into the IFO. What signals are needed for the Guoy phase measurement? Is AS 110 sufficient, or do we need AS55?

Attachment 1: mm_solution_AStable.png  55 kB  | Hide | Hide all
mm_solution_AStable.png
Attachment 2: AStable_beampath.pdf  744 kB  | Hide | Hide all
AStable_beampath.pdf
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