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Entry  Sun Jul 27 19:46:16 2014, Evan, DailyProgress, optic, BRDF of AlGaAs mirror 137B1 ccdImage.pdf137brdf.pdf
    Reply  Tue Jul 29 11:40:09 2014, Evan, DailyProgress, optic, BRDF of AlGaAs mirror 143 143brdf.pdf
       Reply  Wed Jul 30 17:47:56 2014, tara, DailyProgress, optic, BRDF of AlGaAs mirror 143 
Message ID: 1462     Entry time: Wed Jul 30 17:47:56 2014     In reply to: 1461
Author: tara 
Type: DailyProgress 
Category: optic 
Subject: BRDF of AlGaAs mirror 143 

 I used the setup to measure scattered loss from an REO mirror (mirror for iLIGO refcav, the one we measured coating thermal noise) and get 6 ppm. This number agrees quite well with the previous Finesse measurement.

 

  Finesse measurement from REO mirrors = 9700 , see PSL:424 The absorption loss in each mirror is ~ 5 ppm ( from photo thermal measurement, see PSL:1375). The measured finesse infers that the roundtrip loss is ~ 24 ppm, see here. So each mirror has ~ 12 ppm loss. With ~ 5ppm absorption loss, we can expect ~ 6-7 ppm loss for scattered loss.  So this measurement roughly says that our scattered light setup and calibration is ok.

 

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