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rINSTCONTROL/Measurement and analysis routines/@MyPhaseModCal/MyPhaseModCal.m
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MyPhaseModCal.m
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% Routine for the calibration of beta-factor characterizing the phase
% modulation of light. Data is a heterodyne signal spectrum.
classdef MyPhaseModCal < MyAnalysisRoutine
properties (Access = public)
Data MyTrace
end
properties (GetAccess = public, SetAccess = protected)
Axes
end
methods (Access = public)
function this = MyPhaseModCal(varargin)
p = inputParser();
addParameter(p, 'Data', MyTrace());
addParameter(p, 'Axes', [], @isaxes);
parse(p, varargin{:});
this.Data = p.Data;
this.Axes = p.Axes;
end
%Calculates beta, updates the gui with the value and stores it in
%the class.
function calcBeta(this)
%Number of points next to peak we will use to find the area
%under each peak
n=10;
% Finding the index of the the centeral maximum and the side bands
min_pk_dist=200;
[peaks,pk_inds] = findpeaks(this.Data.y,...
'minpeakdistance',min_pk_dist);
%First we sort by height of the peaks
amp_sort=sortrows([peaks, pk_inds]);
%Then we sort the five highest peaks by location
sort_mat=sortrows(amp_sort((end-4):end,:),2);
%The sorted indices of the peaks
ind_sort=sort_mat(:,2);
% Finds indices for the data in the neighborhood of each peak
%Peak 1 is the leftmost (2nd order peak), Peak 2 is the left
%1st order peak, Peak 3 is the central peak etc.
ind_pks=cell(5,1);
for i=1:5
ind_pks{i}=(ind_sort(i)-n):(ind_sort(i)+n);
end
%Here we integrate the data surrounding the peaks and take the
%square root of the areas.
v_rms_pks=cellfun(@(x) sqrt(integrate(this.Data,x)),ind_pks);
% Then we can calculate the FM beta by using:
sdratio_01 = 0.5*(v_rms_pks(4)+v_rms_pks(2))/v_rms_pks(3);
sdratio_02 = 0.5*(v_rms_pks(5)+v_rms_pks(1))/v_rms_pks(3);
syms b;
%Then find the beta by numerically solution of the bessel
%functions
beta_01 = double(vpasolve(besselj(1,b) == ...
sdratio_01 * besselj(0,b), b, 2*sdratio_01));
beta_02 = double(vpasolve(besselj(2,b) == ...
sdratio_02 * besselj(0,b), b, 2*sdratio_02));
%We use beta_02 as it is less affected by residual intensity
%noise.
this.beta=beta_02;
%Sets the values on the GUI
set(this.Gui.Beta02,'String',num2str(beta_02,5));
set(this.Gui.Beta01,'String',num2str(beta_01,5));
end
end
end
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