65 lines
1.4 KiB
Matlab
65 lines
1.4 KiB
Matlab
clear
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close all
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clc
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format compact
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% These calculations are based on Ashkin's article "Forces of a single-beam
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% gradient laser trap on a dielectric sphere in the ray optics regime".
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% There are axial forces only
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load_constants
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import factors.*
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% Factors plots
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theta = linspace(0, pi/2, 500);
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figure
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plot(theta, Qs(theta, pi/4), theta, -Qg(theta, pi/4), theta, Qmag(theta, pi/4))
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grid
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xlabel('$\theta$, $^{\circ}$', 'Interpreter', 'latex')
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ylabel('Q')
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% Intensity profile plots
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rho = linspace(-r_max, r_max, 500);
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figure
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plot(rho, I(rho)/max(I(rho)),'k')
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grid
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xlabel('r, м')
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ylabel('I(r)')
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% Integration
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G0 = 2/(A*pi^2*r_max^2*w0^2);
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Qres_g = @(z) G0 * integral2(@(beta,r) r.*I(r).*...
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iscomplex(Qgz(r,z)),0,2*pi,0,r_max,...
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'Method','iterated','AbsTol',1e-6,'RelTol',1e-6);
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Qres_s = @(z) G0 * integral2(@(beta,r) r.*I(r).*...
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iscomplex(Qsz(r,z)),0,2*pi,0,r_max,...
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'Method','iterated','AbsTol',1e-6,'RelTol',1e-6);
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% Calulation
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N = 200;
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z = linspace(-2*Rsp,2*Rsp,N);
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Axial_g = zeros(1,N);
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Axial_s = zeros(1,N);
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wb = waitbar(0, 'Calculating...');
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for ii = 1:N
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Axial_g(ii) = Qres_g(z(ii));
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Axial_s(ii) = Qres_s(z(ii));
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waitbar(ii / N, wb, 'Calculating...');
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end
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close(wb);
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Axial_g = fliplr(Axial_g);
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Axial_s = fliplr(Axial_s);
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Axial = Axial_g + Axial_s;
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z = -fliplr(z);
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% Plots
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figure
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plot(z,F0*Axial_g,'b-.',z,F0*Axial_s,'r--',z,F0*Axial,'k')
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legend('F_{g}','F_{s}','F_{t}')
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xlabel('r, м')
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ylabel('F, Н')
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grid |