40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  PSL  Not logged in ELOG logo
Message ID: 1648     Entry time: Mon Jun 20 23:07:32 2016
Author: awade 
Type: DailyProgress 
Category: Laser 
Subject: Repeating beam profiles of North EPRO (M126N-1064-700)  

Earlier I posted a beam profile of the north laser path that seemed to have much greater uncertainty on the horizontal axis (see: https://nodus.ligo.caltech.edu:8081/CTN/1646). Antonio was a little concerned that maybe the iris or something else was clipping, this might have caused some defraction. 

I cleaned the first window and replaced the second window with another W2-PW1-1037-UV-45P (AR coated on both sides), then the profiling camera was realigned. A couple of screen shots are attached of the beam profile at a couple of points, it doesn't look nicely Gaussian close in, I'm not sure what is causing this, but this is the beam directly from the laser (via two windows).

The profiles were fitted using the D4σ method (standard and default) to find the 1/e^2 drop off of the beam radius (as was done in all the previous posts).

This time the data looks better for the horizontal.

--

The data is as follows:
z= [0 25 100 125 150 175 200 225 250 300 325 350 375 400 425]*1e-3 + (72e-3+24e-3+63e-3); % Distance from the laser head. The fixed added on value at the end is the distance to the first measurment point
W_horz = [752.9 804.0 957.5 1010.9 1077.6 1136.6 1190.7 1244.2 1301.1 1407.0 1461.6 1513.9 1585.5 1622.6 1668.0]*1e-6/2; % Horizonal beam radius
W_vert = [696.0 754.0 995.0 1066.2 1130.2 1210.7 1286.8 1356.9 1414.7 1580.1 1642.9 1697.5 1786.8 1859.7 1951.1]*1e-6/2; % Vertical beam radius

 

And fitted values are:

Horz. beam waist = 272.0952 um
Horz. beam waist position = -60.2164 mm
Vert. beam waist = 216.5147 um
Vert. beam waist position = -22.9082 mm

These are very similar to the previous measurement. Plots and configuration schematic are attached.

 

Attachment 1: RedoneProfileMeasurmentNorthLaserSetup.eps  2.150 MB  | Hide | Hide all
RedoneProfileMeasurmentNorthLaserSetup.eps
Attachment 2: data20160620_RedoneNorthLaserBeamProfileDataAndFitRedone.eps  134 kB  | Hide | Hide all
data20160620_RedoneNorthLaserBeamProfileDataAndFitRedone.eps
Attachment 3: 20160620_ScreenShotDataRay0mmfromStart.png  289 kB  | Hide | Hide all
20160620_ScreenShotDataRay0mmfromStart.png
Attachment 4: 20160620_ScreenShotDataRay200mmfromStart.png  312 kB  | Hide | Hide all
20160620_ScreenShotDataRay200mmfromStart.png
Attachment 5: 20160620_ScreenShotDataRay300mmfromStart.png  303 kB  | Hide | Hide all
20160620_ScreenShotDataRay300mmfromStart.png
ELOG V3.1.3-