Coherent Backscattering from Multiple Scattering Systems - KOPS ...

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MATLAB codes function R = reflectivity (n1,n2) if n1 > n2 theta_totalreflection = asin (n2/n1) ; else theta_totalreflection = pi/2 ; end theta1 = 0 : pi/100 : theta_totalreflection ; theta2 = theta_totalreflection+pi/100 : pi/100 : pi/2 ; theta = [ theta1, theta2 ] ; R_parallel = ( n1 * cos(theta1) ... - n2 * sqrt( 1 - (n1 / n2 * sin(theta1)).^2 ) ).^2 ./ ... ( n1 * cos(theta1) ... + n2 * sqrt( 1 - (n1 / n2 * sin(theta1)).^2 ) ).^2 ; R_parallel = [ R_parallel , ones(size(theta2)) ] ; R_perp = ( n1 * sqrt( 1 - (n1 / n2 * sin(theta1)).^2 ) ... - n2 * cos(theta1) ).^2 ./ ... ( n1 * sqrt( 1 - (n1 / n2 * sin(theta1)).^2 ) ... + n2 * cos(theta1) ).^2 ; R_perp = [ R_perp , ones(size(theta2)) ] ; C1 = trapz ( theta , ... (R_parallel + R_perp) / 2 .* sin(theta) .* cos(theta) ) ; C2 = trapz ( -theta , ... (R_parallel + R_perp) / 2 .* sin(-theta) .* (cos(-theta)).^2 ) ; R = ( 3 * C2 + 2 * C1 ) / ( 3 * C2 - 2 * C1 + 2 ) ; end 86
Evaluation of the small angle data Evaluation of the small angle data The following MATLAB code is a very simplified version of the evaluation program for the small angle setup; it will not work with all data. The script finds the backscattering direction θ = 0 in the CCD image and calculates either an azimuthal average or a radial profile section of the backscattering cone. The signals of the CCD chip and their errors (se = standard error) are stored in two uint16 binary files. Depending on the preprocessing the numbers can have big (ieee-be) or little (ieee-le) endian. function small_angle_evaluation %% Open file endian = ’ieee-be’ ; % alternative: ’ieee-le’ fid = fopen (’C:\Examples\example.i16’, ’r’) ; matrix = fread (fid, [2048,2048], ’uint16’, 0, endian) ; fclose (fid) ; fid = fopen (’C:\Examples\example_se.i16’, ’r’) ; errormatrix = fread (fid, [2048,2048], ’uint16’, 0, endian) ; fclose (fid) ; %% Find peak % the image has to be scaled to have intensities in [0,1] by dividing by the % largest possible intensity (i.e. 65535) dummy = matrix / 65535 ; % turn matrix into black-and-white picture (conetip forms white blob, % everything else is black) n = 5 ; dummy = medfilt2 (dummy, [n,n]) ; maximum = max ( max (dummy) ) ; level = 0.95 * maximum ; bwimage = im2bw (dummy, level) ; % smooth picture so that fluctuations do % not disturb the search for the cone % find center of the blob => scattering angle theta = 0 dummy = bwlabel (bwimage) ; % label connected components in binary image regions = regionprops (dummy, ’Area’, ’Centroid’) ; % measure properties % of image regions [area,index] = max ( [ regions.Area ] ) ; 87
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Dissertation Coherent Backscatterin
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Ein kurzer Überblick Streuung ist
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Ein kurzer Überblick portweglänge
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Contents Ein kurzer Überblick i Da
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1 Introduction There have been many
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2 Theory In scattering theory, the
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2.2 Single scattering - Mie theory
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2.2 Single scattering - Mie theory
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2.3 Random walk and diffusion scatt
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2.3 Random walk and diffusion of pr
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2.4 The influence of boundaries Fig
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2.5 Photon flux from a surface The
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2.6 On polarization and interferenc
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2.6 On polarization and interferenc
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2.7 The theory of coherent backscat
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2.7 The theory of coherent backscat
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3 Setups 3.1 Laser System The key p
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3.2 Wide Angle Setup 1 .0 0 .8 h e
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3.3 Small Angle Setup 1 0.998 0.996
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3.3 Small Angle Setup Figure 3.6: T
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3.4 Time Of Flight Setup Figure 3.8
Page 43 and 44: 4 Samples 4.1 Sample characterizati
Page 45 and 46: 4.1 Sample characterization techniq
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Page 49 and 50: 4.2 The samples Figure 4.5: Fluidiz
Page 51 and 52: 5 Experiments 5.1 Conservation of e
Page 53 and 54: 5.1 Conservation of energy in coher
Page 65 and 66: 5.2 The coherent backscattering con
Page 77 and 78: 6 Summary The focus of the work pre
Page 79 and 80: Bibliography [1] http://www.schneid
Page 81 and 82: Bibliography [34] E. Larose, L. Mar
Page 83 and 84: Figures and Tables Figures Backscat
Page 85 and 86: Figures and Tables Tables 4.1 Collo
Page 87 and 88: MATLAB codes Angular intensity dist
Page 89 and 90: Evaluation of the wide angle data E
Page 91 and 92: Evaluation of the wide angle data %
Page 93: Evaluation of the wide angle data f
Page 97 and 98: Evaluation of the small angle data
Page 99: Evaluation of the small angle data
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