A pickoff of the 700 mW north laser was made with two UV grade fused silica widows to make a beam profile measurement. Attached figure shows setup.
Here the data is for the North laser (measured on June 17 2016) operating at 701.1 mW (Adj number = 0). The laser was allowed time to warm up and a pickoff of the beam was taken by first reflecting off the front surface of a W1-PW1-1025-UV-1064-45UND UV grade fused silica window and then a W2-PW1-1037-UV-45P UV grade fused silica window with AR coating on front and back: the resulting light was ~200 uW. Beam widths as a function of distance were collected using the WinCamD after isolating a single spot with an iris. Because of the need for two windows, it difficult to sample less than 150 mm from the laser head.
The data is as follows:
z= [0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 425]*1e-3 + (72e-3+25e-3+62e-3); % Distance from the laser head. The fixed added on value at the end is the distance to the first measurement point
W_horz = [768 829 866.2 915.7 965.3 1018.0 1072.3 1135.7 1180.0 1231.7 1285.1 1346.9 1402.5 1462.6 1517.0 1568.1 1648.3 1700.1]*1e-6/2; % Horizontal beam radius
W_vert = [760.4 762.8 870.1 971.8 983.2 1119.2 1223.5 1231.2 1353.5 1428.1 1522.5 1558.4 1619.4 1729.9 1813.9 1856.0 1888.6 1969.1]*1e-6/2; % Vertical beam radius
The fitting routine, plot and schematic of setup are attached.
The fit to the data gave:
Horz. beam waist = 272.6917 um
Horz. beam waist position = -62.2656 mm
Vert. beam waist = 213.3873 um
Vert. beam waist position = -36.3761 mm
For some reason the horziontal data looks noiser, I'm not sure what is happening there.
-awade Mon Jun 20 12:16:23 2016
%% Fitting routie for beam profiling measurments
% This model takes a set of data values for scaned beam widths as a
% function of distances an computes the waist and its position using the
% GaussProFit routine.
clear all % clear the decks
addpath('~/Box Sync/TCNlab_shared/standardMatlablibrary/') % Adds path to standard Matlab functions used for the TCN labwork