New routine to plot insitu images across runs, new script to calculate interference pattern, potential for an optical accordion lattice.

This commit is contained in:
Karthik 2025-07-18 22:10:05 +02:00
parent 64229ecd69
commit f6981b9233
3 changed files with 916 additions and 8 deletions

View File

@ -4,16 +4,16 @@ groupList = ["/images/MOT_3D_Camera/in_situ_absorption", "/images/ODT_1_Axi
"/images/ODT_2_Axis_Camera/in_situ_absorption", "/images/Horizontal_Axis_Camera/in_situ_absorption", ...
"/images/Vertical_Axis_Camera/in_situ_absorption"];
folderPath = "//DyLabNAS/Data/TwoDGas/2025/04/02/";
folderPath = "//DyLabNAS/Data/TwoDGas/2025/07/16/";
run = '0007';
run = '0002';
folderPath = strcat(folderPath, run);
cam = 5;
angle = 0;
center = [1285, 2100];
center = [1430, 2025];
span = [200, 200];
fraction = [0.1, 0.1];
@ -25,13 +25,13 @@ ImagingMode = 'HighIntensity';
PulseDuration = 5e-6;
% Plotting and saving
scan_parameter = 'rot_mag_fin_pol_angle';
scan_parameter = 'evap_rot_mag_field';
scan_groups = 0:10:50;
savefileName = 'DropletsToStripes';
savefileName = 'Droplets';
font = 'Bahnschrift';
% Flags
skipUnshuffling = false;
skipUnshuffling = true;
%% ===== Load and compute OD image, rotate and extract ROI for analysis =====
% Get a list of all files in the folder with the desired file name pattern.
@ -175,14 +175,14 @@ for k = 1 : length(od_imgs)
'Interpreter', 'tex', 'Units', 'normalized', ...
'HorizontalAlignment', 'right', 'VerticalAlignment', 'top');
end
colorbarHandle = colorbar;
ylabel(colorbarHandle, 'Optical Density', 'Rotation', -90, 'FontSize', 14, 'FontName', font);
xlabel('x (\mum)', 'Interpreter', 'tex', 'FontSize', 14, 'FontName', font);
ylabel('y (\mum)', 'Interpreter', 'tex', 'FontSize', 14, 'FontName', font);
title('OD Image', 'FontSize', 16, 'FontWeight', 'bold', 'Interpreter', 'tex', 'FontName', font);
drawnow;
pause(0.5);
end

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@ -0,0 +1,767 @@
% === Parameters ===
baseFolder = '//DyLabNAS/Data/TwoDGas/2025/04/';
dates = ["01", "02"];
runs = {
["0059", "0060", "0061"],
["0007", "0008", "0009", "0010", "0011"]
};
scan_groups = 0:10:50;
scan_parameter = 'rot_mag_fin_pol_angle';
cam = 5;
% Image cropping and alignment
angle = 0;
center = [1285, 2100];
span = [200, 200];
fraction = [0.1, 0.1];
% Imaging and calibration parameters
pixel_size = 5.86e-6; % in meters
magnification = 23.94;
removeFringes = false;
ImagingMode = 'LowIntensity';
PulseDuration = 5e-6;
% Optional visualization / zooming
options.zoom_size = 50;
% Optional flags or settings struct
skipUnshuffling = false;
skipPreprocessing = true;
skipMasking = true;
skipIntensityThresholding = true;
skipBinarization = true;
groupList = ["/images/MOT_3D_Camera/in_situ_absorption", "/images/ODT_1_Axis_Camera/in_situ_absorption", ...
"/images/ODT_2_Axis_Camera/in_situ_absorption", "/images/Horizontal_Axis_Camera/in_situ_absorption", ...
"/images/Vertical_Axis_Camera/in_situ_absorption"];
%%
allData = {}; % now a growing list of structs per B field
dataCounter = 1;
for i = 1:length(dates)
dateStr = dates(i);
runList = runs{i};
for j = 1:length(runList)
folderPath = fullfile(baseFolder, dateStr, runList{j});
filePattern = fullfile(folderPath, '*.h5');
files = dir(filePattern);
refimages = zeros(span(1) + 1, span(2) + 1, length(files));
absimages = zeros(span(1) + 1, span(2) + 1, length(files));
for k = 1 : length(files)
baseFileName = files(k).name;
fullFileName = fullfile(files(k).folder, baseFileName);
fprintf(1, 'Now reading %s\n', fullFileName);
atm_img = double(imrotate(h5read(fullFileName, append(groupList(cam), "/atoms")), angle));
bkg_img = double(imrotate(h5read(fullFileName, append(groupList(cam), "/background")), angle));
dark_img = double(imrotate(h5read(fullFileName, append(groupList(cam), "/dark")), angle));
refimages(:,:,k) = subtractBackgroundOffset(cropODImage(bkg_img, center, span), fraction)';
absimages(:,:,k) = subtractBackgroundOffset(cropODImage(calculateODImage(atm_img, bkg_img, dark_img, ImagingMode, PulseDuration), center, span), fraction)';
end
% ===== Fringe removal =====
if removeFringes
optrefimages = removefringesInImage(absimages, refimages);
absimages_fringe_removed = absimages(:, :, :) - optrefimages(:, :, :);
nimgs = size(absimages_fringe_removed,3);
od_imgs = cell(1, nimgs);
for k = 1:nimgs
od_imgs{k} = absimages_fringe_removed(:, :, k);
end
else
nimgs = size(absimages(:, :, :),3);
od_imgs = cell(1, nimgs);
for k = 1:nimgs
od_imgs{k} = absimages(:, :, k);
end
end
%% ===== Get rotation angles =====
scan_parameter_values = zeros(1, length(files));
% Get information about the '/globals' group
for k = 1 : length(files)
baseFileName = files(k).name;
fullFileName = fullfile(files(k).folder, baseFileName);
info = h5info(fullFileName, '/globals');
for i = 1:length(info.Attributes)
if strcmp(info.Attributes(i).Name, scan_parameter)
if strcmp(scan_parameter, 'rot_mag_fin_pol_angle')
scan_parameter_values(k) = 180 - info.Attributes(i).Value;
else
scan_parameter_values(k) = info.Attributes(i).Value;
end
end
if strcmp(info.Attributes(i).Name, "rot_mag_field")
B = info.Attributes(i).Value;
end
end
end
% ===== Unshuffle if necessary to do so =====
if ~skipUnshuffling
n_values = length(scan_groups);
n_total = length(scan_parameter_values);
% Infer number of repetitions
n_reps = n_total / n_values;
% Preallocate ordered arrays
ordered_scan_values = zeros(1, n_total);
ordered_od_imgs = cell(1, n_total);
counter = 1;
for rep = 1:n_reps
for val = scan_groups
% Find the next unused match for this val
idx = find(scan_parameter_values == val, 1, 'first');
% Assign and remove from list to avoid duplicates
ordered_scan_values(counter) = scan_parameter_values(idx);
ordered_od_imgs{counter} = od_imgs{idx};
% Mark as used by removing
scan_parameter_values(idx) = NaN; % NaN is safe since original values are 0:5:45
od_imgs{idx} = []; % empty cell so it won't be matched again
counter = counter + 1;
end
end
% Now assign back
scan_parameter_values = ordered_scan_values;
od_imgs = ordered_od_imgs;
end
% === Reshape ===
od_imgs_reshaped = reshape(od_imgs, [length(scan_groups), n_reps]);
% === Store ===
allData{dataCounter} = struct(...
'B', B, ...
'theta_vals', scan_groups, ...
'od_imgs', od_imgs_reshaped ...
);
dataCounter = dataCounter + 1;
end
end
%% === % Plot PD - 1st rep of each θ per B-field ===
[theta_vals, ~, idx] = unique(scan_parameter_values);
nB = numel(allData);
nTheta = numel(theta_vals);
% Select every 2nd B-field index
idxToPlot = 1:2:nB; % indices 1, 3, 5, ...
% Update number of B-fields to plot
nB_new = numel(idxToPlot);
figure(101); clf;
% Make the figure wider to fit the colorbar comfortably
set(gcf, 'Position', [100, 100, 1300, 800]);
% Create tiled layout with some right padding to reserve space for colorbar
t = tiledlayout(nB_new, nTheta, 'TileSpacing', 'compact', 'Padding', 'compact');
font = 'Bahnschrift';
allAxes = gobjects(nB_new, nTheta);
for new_i = 1:nB_new
i = idxToPlot(new_i); % original index in allData
data = allData{i};
for j = 1:nTheta
ax = nexttile((new_i-1)*nTheta + j);
allAxes(new_i,j) = ax;
od = data(j).od_imgs;
imagesc(od, 'Parent', ax);
set(ax, 'YDir', 'normal');
axis(ax, 'image');
ax.XTick = [];
ax.YTick = [];
colormap(ax, Colormaps.inferno());
end
end
% Use colorbar associated with the last image tile
cb = colorbar('Location', 'eastoutside');
cb.Layout.Tile = 'east'; % Attach it to the layout edge
cb.FontName = font;
cb.FontSize = 18;
cb.Label.FontSize = 20;
cb.Label.Rotation = 90;
cb.Label.VerticalAlignment = 'bottom';
cb.Label.HorizontalAlignment = 'center';
cb.Direction = 'normal'; % Ensure ticks go bottom-to-top
% Add x and y tick labels along bottom and left
% Use bottom row for θ ticks
for j = 1:nTheta
ax = allAxes(end, j);
ax.XTick = size(od,2)/2;
ax.XTickLabel = sprintf('%d°', theta_vals(j));
ax.XTickLabelRotation = 0;
ax.FontName = font;
ax.FontSize = 20;
end
% Use first column for B ticks (only the plotted subset)
for new_i = 1:nB_new
i = idxToPlot(new_i);
ax = allAxes(new_i, 1);
ax.YTick = size(od,1)/2;
ax.YTickLabel = sprintf('%.2f G', allData{i}(1).B);
ax.FontName = font;
ax.FontSize = 20;
end
%% Helper Functions
function [IMGFFT, IMGPR] = computeFourierTransform(I, skipPreprocessing, skipMasking, skipIntensityThresholding, skipBinarization)
% computeFourierSpectrum - Computes the 2D Fourier power spectrum
% of binarized and enhanced lattice image features, with optional central mask.
%
% Inputs:
% I - Grayscale or RGB image matrix
%
% Output:
% F_mag - 2D Fourier power spectrum (shifted)
if ~skipPreprocessing
% Preprocessing: Denoise
filtered = imgaussfilt(I, 10);
IMGPR = I - filtered; % adjust sigma as needed
else
IMGPR = I;
end
if ~skipMasking
[rows, cols] = size(IMGPR);
[X, Y] = meshgrid(1:cols, 1:rows);
% Elliptical mask parameters
cx = cols / 2;
cy = rows / 2;
% Shifted coordinates
x = X - cx;
y = Y - cy;
% Ellipse semi-axes
rx = 0.4 * cols;
ry = 0.2 * rows;
% Rotation angle in degrees -> radians
theta_deg = 30; % Adjust as needed
theta = deg2rad(theta_deg);
% Rotated ellipse equation
cos_t = cos(theta);
sin_t = sin(theta);
x_rot = (x * cos_t + y * sin_t);
y_rot = (-x * sin_t + y * cos_t);
ellipseMask = (x_rot.^2) / rx^2 + (y_rot.^2) / ry^2 <= 1;
% Apply cutout mask
IMGPR = IMGPR .* ellipseMask;
end
if ~skipIntensityThresholding
% Apply global intensity threshold mask
intensity_thresh = 0.20;
intensity_mask = IMGPR > intensity_thresh;
IMGPR = IMGPR .* intensity_mask;
end
if ~skipBinarization
% Adaptive binarization and cleanup
IMGPR = imbinarize(IMGPR, 'adaptive', 'Sensitivity', 0.0);
IMGPR = imdilate(IMGPR, strel('disk', 2));
IMGPR = imerode(IMGPR, strel('disk', 1));
IMGPR = imfill(IMGPR, 'holes');
F = fft2(double(IMGPR)); % Compute 2D Fourier Transform
IMGFFT = abs(fftshift(F))'; % Shift zero frequency to center
else
F = fft2(double(IMGPR)); % Compute 2D Fourier Transform
IMGFFT = abs(fftshift(F))'; % Shift zero frequency to center
end
end
function [k_rho_vals, S_radial] = computeRadialSpectralDistribution(IMGFFT, kx, ky, thetamin, thetamax, num_bins)
% IMGFFT : 2D FFT image (fftshifted and cropped)
% kx, ky : 1D physical wavenumber axes [μm¹] matching FFT size
% thetamin : Minimum angle (in radians)
% thetamax : Maximum angle (in radians)
% num_bins : Number of radial bins
[KX, KY] = meshgrid(kx, ky);
K_rho = sqrt(KX.^2 + KY.^2);
Theta = atan2(KY, KX);
if thetamin < thetamax
angle_mask = (Theta >= thetamin) & (Theta <= thetamax);
else
angle_mask = (Theta >= thetamin) | (Theta <= thetamax);
end
power_spectrum = abs(IMGFFT).^2;
r_min = min(K_rho(angle_mask));
r_max = max(K_rho(angle_mask));
r_edges = linspace(r_min, r_max, num_bins + 1);
k_rho_vals = 0.5 * (r_edges(1:end-1) + r_edges(2:end));
S_radial = zeros(1, num_bins);
for i = 1:num_bins
r_low = r_edges(i);
r_high = r_edges(i + 1);
radial_mask = (K_rho >= r_low) & (K_rho < r_high);
full_mask = radial_mask & angle_mask;
S_radial(i) = sum(power_spectrum(full_mask));
end
end
function [theta_vals, S_theta] = computeAngularSpectralDistribution(IMGFFT, r_min, r_max, num_bins, threshold, sigma, windowSize)
% Apply threshold to isolate strong peaks
IMGFFT(IMGFFT < threshold) = 0;
% Prepare polar coordinates
[ny, nx] = size(IMGFFT);
[X, Y] = meshgrid(1:nx, 1:ny);
cx = ceil(nx/2);
cy = ceil(ny/2);
R = sqrt((X - cx).^2 + (Y - cy).^2);
Theta = atan2(Y - cy, X - cx); % range [-pi, pi]
% Choose radial band
radial_mask = (R >= r_min) & (R <= r_max);
% Initialize angular structure factor
S_theta = zeros(1, num_bins);
theta_vals = linspace(0, pi, num_bins);
% Loop through angle bins
for i = 1:num_bins
angle_start = (i-1) * pi / num_bins;
angle_end = i * pi / num_bins;
angle_mask = (Theta >= angle_start & Theta < angle_end);
bin_mask = radial_mask & angle_mask;
fft_angle = IMGFFT .* bin_mask;
S_theta(i) = sum(sum(abs(fft_angle).^2));
end
% Smooth using either Gaussian or moving average
if exist('sigma', 'var') && ~isempty(sigma)
% Gaussian convolution
half_width = ceil(3 * sigma);
x = -half_width:half_width;
gauss_kernel = exp(-x.^2 / (2 * sigma^2));
gauss_kernel = gauss_kernel / sum(gauss_kernel);
% Circular convolution
S_theta = conv([S_theta(end-half_width+1:end), S_theta, S_theta(1:half_width)], ...
gauss_kernel, 'same');
S_theta = S_theta(half_width+1:end-half_width);
elseif exist('windowSize', 'var') && ~isempty(windowSize)
% Moving average via convolution (circular)
pad = floor(windowSize / 2);
kernel = ones(1, windowSize) / windowSize;
S_theta = conv([S_theta(end-pad+1:end), S_theta, S_theta(1:pad)], kernel, 'same');
S_theta = S_theta(pad+1:end-pad);
end
end
function contrast = computeRadialSpectralContrast(IMGFFT, r_min, r_max, threshold)
% Apply threshold to isolate strong peaks
IMGFFT(IMGFFT < threshold) = 0;
% Prepare polar coordinates
[ny, nx] = size(IMGFFT);
[X, Y] = meshgrid(1:nx, 1:ny);
cx = ceil(nx/2);
cy = ceil(ny/2);
R = sqrt((X - cx).^2 + (Y - cy).^2);
% Ring region (annulus) mask
ring_mask = (R >= r_min) & (R <= r_max);
% Squared magnitude in the ring
ring_power = abs(IMGFFT).^2 .* ring_mask;
% Maximum power in the ring
ring_max = max(ring_power(:));
% Power at the DC component
dc_power = abs(IMGFFT(cy, cx))^2;
% Avoid division by zero
if dc_power == 0
contrast = Inf; % or NaN or 0, depending on how you want to handle this
else
contrast = ring_max / dc_power;
end
end
function ret = getBkgOffsetFromCorners(img, x_fraction, y_fraction)
% image must be a 2D numerical array
[dim1, dim2] = size(img);
s1 = img(1:round(dim1 * y_fraction), 1:round(dim2 * x_fraction));
s2 = img(1:round(dim1 * y_fraction), round(dim2 - dim2 * x_fraction):dim2);
s3 = img(round(dim1 - dim1 * y_fraction):dim1, 1:round(dim2 * x_fraction));
s4 = img(round(dim1 - dim1 * y_fraction):dim1, round(dim2 - dim2 * x_fraction):dim2);
ret = mean([mean(s1(:)), mean(s2(:)), mean(s3(:)), mean(s4(:))]);
end
function ret = subtractBackgroundOffset(img, fraction)
% Remove the background from the image.
% :param dataArray: The image
% :type dataArray: xarray DataArray
% :param x_fraction: The fraction of the pixels used in x axis
% :type x_fraction: float
% :param y_fraction: The fraction of the pixels used in y axis
% :type y_fraction: float
% :return: The image after removing background
% :rtype: xarray DataArray
x_fraction = fraction(1);
y_fraction = fraction(2);
offset = getBkgOffsetFromCorners(img, x_fraction, y_fraction);
ret = img - offset;
end
function ret = cropODImage(img, center, span)
% Crop the image according to the region of interest (ROI).
% :param dataSet: The images
% :type dataSet: xarray DataArray or DataSet
% :param center: The center of region of interest (ROI)
% :type center: tuple
% :param span: The span of region of interest (ROI)
% :type span: tuple
% :return: The cropped images
% :rtype: xarray DataArray or DataSet
x_start = floor(center(1) - span(1) / 2);
x_end = floor(center(1) + span(1) / 2);
y_start = floor(center(2) - span(2) / 2);
y_end = floor(center(2) + span(2) / 2);
ret = img(y_start:y_end, x_start:x_end);
end
function imageOD = calculateODImage(imageAtom, imageBackground, imageDark, mode, exposureTime)
%CALCULATEODIMAGE Calculates the optical density (OD) image for absorption imaging.
%
% imageOD = calculateODImage(imageAtom, imageBackground, imageDark, mode, exposureTime)
%
% Inputs:
% imageAtom - Image with atoms
% imageBackground - Image without atoms
% imageDark - Image without light
% mode - 'LowIntensity' (default) or 'HighIntensity'
% exposureTime - Required only for 'HighIntensity' [in seconds]
%
% Output:
% imageOD - Computed OD image
%
arguments
imageAtom (:,:) {mustBeNumeric}
imageBackground (:,:) {mustBeNumeric}
imageDark (:,:) {mustBeNumeric}
mode char {mustBeMember(mode, {'LowIntensity', 'HighIntensity'})} = 'LowIntensity'
exposureTime double = NaN
end
% Compute numerator and denominator
numerator = imageBackground - imageDark;
denominator = imageAtom - imageDark;
% Avoid division by zero
numerator(numerator == 0) = 1;
denominator(denominator == 0) = 1;
% Calculate OD based on mode
switch mode
case 'LowIntensity'
imageOD = -log(abs(denominator ./ numerator));
case 'HighIntensity'
if isnan(exposureTime)
error('Exposure time must be provided for HighIntensity mode.');
end
imageOD = abs(denominator ./ numerator);
imageOD = -log(imageOD) + (numerator - denominator) ./ (7000 * (exposureTime / 5e-6));
end
end
function drawODOverlays(x1, y1, x2, y2)
% Parameters
tick_spacing = 10; % µm between ticks
tick_length = 2; % µm tick mark length
line_color = [0.5 0.5 0.5];
tick_color = [0.5 0.5 0.5];
font_size = 10;
% Vector from start to end
dx = x2 - x1;
dy = y2 - y1;
L = sqrt(dx^2 + dy^2);
% Unit direction vector along diagonal
ux = dx / L;
uy = dy / L;
% Perpendicular unit vector for ticks
perp_ux = -uy;
perp_uy = ux;
% Midpoint (center)
xc = (x1 + x2) / 2;
yc = (y1 + y2) / 2;
% Number of positive and negative ticks
n_ticks = floor(L / (2 * tick_spacing));
% Draw main diagonal line
plot([x1 x2], [y1 y2], '--', 'Color', line_color, 'LineWidth', 1.2);
for i = -n_ticks:n_ticks
d = i * tick_spacing;
xt = xc + d * ux;
yt = yc + d * uy;
% Tick line endpoints
xt1 = xt - 0.5 * tick_length * perp_ux;
yt1 = yt - 0.5 * tick_length * perp_uy;
xt2 = xt + 0.5 * tick_length * perp_ux;
yt2 = yt + 0.5 * tick_length * perp_uy;
% Draw tick
plot([xt1 xt2], [yt1 yt2], '--', 'Color', tick_color, 'LineWidth', 1);
% Label: centered at tick, offset slightly along diagonal
if d ~= 0
text(xt, yt, sprintf('%+d', d), ...
'Color', tick_color, ...
'FontSize', font_size, ...
'HorizontalAlignment', 'center', ...
'VerticalAlignment', 'bottom', ...
'Rotation', atan2d(dy, dx));
end
end
end
function drawPSOverlays(kx, ky, r_min, r_max)
% drawFFTOverlays - Draw overlays on existing FFT plot:
% - Radial lines every 30°
% - Annular highlight with white (upper half) and gray (lower half) circles between r_min and r_max
% - Horizontal white bands at ky=0 in annulus region
% - Scale ticks and labels every 1 μm¹ along each radial line
%
% Inputs:
% kx, ky - reciprocal space vectors (μm¹)
% r_min - inner annulus radius offset index (integer)
% r_max - outer annulus radius offset index (integer)
%
% Example:
% hold on;
% drawFFTOverlays(kx, ky, 10, 30);
hold on
% === Overlay Radial Lines + Scales ===
[kx_grid, ky_grid] = meshgrid(kx, ky);
[~, kr_grid] = cart2pol(kx_grid, ky_grid); % kr_grid in μm¹
max_kx = max(kx);
max_ky = max(ky);
for angle = 0 : pi/6 : pi
x_line = [0, max_kx] * cos(angle);
y_line = [0, max_ky] * sin(angle);
% Plot radial lines
plot(x_line, y_line, '--', 'Color', [0.5 0.5 0.5], 'LineWidth', 1.2);
plot(x_line, -y_line, '--', 'Color', [0.5 0.5 0.5], 'LineWidth', 1.2);
% Draw scale ticks along positive radial line
drawTicksAlongLine(0, 0, x_line(2), y_line(2));
% Draw scale ticks along negative radial line (reflect y)
drawTicksAlongLine(0, 0, x_line(2), -y_line(2));
end
% === Overlay Annular Highlight: White (r_min to r_max), Gray elsewhere ===
theta_full = linspace(0, 2*pi, 500);
center_x = ceil(size(kr_grid, 2) / 2);
center_y = ceil(size(kr_grid, 1) / 2);
k_min = kr_grid(center_y, center_x + r_min);
k_max = kr_grid(center_y, center_x + r_max);
% Upper half: white dashed circles
x1_upper = k_min * cos(theta_full(theta_full <= pi));
y1_upper = k_min * sin(theta_full(theta_full <= pi));
x2_upper = k_max * cos(theta_full(theta_full <= pi));
y2_upper = k_max * sin(theta_full(theta_full <= pi));
plot(x1_upper, y1_upper, 'k--', 'LineWidth', 1.2);
plot(x2_upper, y2_upper, 'k--', 'LineWidth', 1.2);
% Lower half: gray dashed circles
x1_lower = k_min * cos(theta_full(theta_full > pi));
y1_lower = k_min * sin(theta_full(theta_full > pi));
x2_lower = k_max * cos(theta_full(theta_full > pi));
y2_lower = k_max * sin(theta_full(theta_full > pi));
plot(x1_lower, y1_lower, '--', 'Color', [0.5 0.5 0.5], 'LineWidth', 1.0);
plot(x2_lower, y2_lower, '--', 'Color', [0.5 0.5 0.5], 'LineWidth', 1.0);
% === Highlight horizontal band across k_y = 0 ===
x_vals = kx;
xW1 = x_vals((x_vals >= -k_max) & (x_vals < -k_min));
xW2 = x_vals((x_vals > k_min) & (x_vals <= k_max));
plot(xW1, zeros(size(xW1)), 'k--', 'LineWidth', 1.2);
plot(xW2, zeros(size(xW2)), 'k--', 'LineWidth', 1.2);
hold off
% --- Nested helper function to draw ticks along a radial line ---
function drawTicksAlongLine(x_start, y_start, x_end, y_end)
% Tick parameters
tick_spacing = 1; % spacing between ticks in μm¹
tick_length = 0.05 * sqrt((x_end - x_start)^2 + (y_end - y_start)^2); % relative tick length
line_color = [0.5 0.5 0.5];
tick_color = [0.5 0.5 0.5];
font_size = 8;
% Vector along the line
dx = x_end - x_start;
dy = y_end - y_start;
L = sqrt(dx^2 + dy^2);
ux = dx / L;
uy = dy / L;
% Perpendicular vector for ticks
perp_ux = -uy;
perp_uy = ux;
% Number of ticks (from 0 up to max length)
n_ticks = floor(L / tick_spacing);
for i = 1:n_ticks
% Position of tick along the line
xt = x_start + i * tick_spacing * ux;
yt = y_start + i * tick_spacing * uy;
% Tick endpoints
xt1 = xt - 0.5 * tick_length * perp_ux;
yt1 = yt - 0.5 * tick_length * perp_uy;
xt2 = xt + 0.5 * tick_length * perp_ux;
yt2 = yt + 0.5 * tick_length * perp_uy;
% Draw tick
plot([xt1 xt2], [yt1 yt2], '-', 'Color', tick_color, 'LineWidth', 1);
% Label with distance (integer)
text(xt, yt, sprintf('%d', i), ...
'Color', tick_color, ...
'FontSize', font_size, ...
'HorizontalAlignment', 'center', ...
'VerticalAlignment', 'bottom', ...
'Rotation', atan2d(dy, dx));
end
end
end
function [optrefimages] = removefringesInImage(absimages, refimages, bgmask)
% removefringesInImage - Fringe removal and noise reduction from absorption images.
% Creates an optimal reference image for each absorption image in a set as
% a linear combination of reference images, with coefficients chosen to
% minimize the least-squares residuals between each absorption image and
% the optimal reference image. The coefficients are obtained by solving a
% linear set of equations using matrix inverse by LU decomposition.
%
% Application of the algorithm is described in C. F. Ockeloen et al, Improved
% detection of small atom numbers through image processing, arXiv:1007.2136 (2010).
%
% Syntax:
% [optrefimages] = removefringesInImage(absimages,refimages,bgmask);
%
% Required inputs:
% absimages - Absorption image data,
% typically 16 bit grayscale images
% refimages - Raw reference image data
% absimages and refimages are both cell arrays containing
% 2D array data. The number of refimages can differ from the
% number of absimages.
%
% Optional inputs:
% bgmask - Array specifying background region used,
% 1=background, 0=data. Defaults to all ones.
% Outputs:
% optrefimages - Cell array of optimal reference images,
% equal in size to absimages.
%
% Dependencies: none
%
% Authors: Shannon Whitlock, Caspar Ockeloen
% Reference: C. F. Ockeloen, A. F. Tauschinsky, R. J. C. Spreeuw, and
% S. Whitlock, Improved detection of small atom numbers through
% image processing, arXiv:1007.2136
% Email:
% May 2009; Last revision: 11 August 2010
% Process inputs
% Set variables, and flatten absorption and reference images
nimgs = size(absimages,3);
nimgsR = size(refimages,3);
xdim = size(absimages(:,:,1),2);
ydim = size(absimages(:,:,1),1);
R = single(reshape(refimages,xdim*ydim,nimgsR));
A = single(reshape(absimages,xdim*ydim,nimgs));
optrefimages=zeros(size(absimages)); % preallocate
if not(exist('bgmask','var')); bgmask=ones(ydim,xdim); end
k = find(bgmask(:)==1); % Index k specifying background region
% Ensure there are no duplicate reference images
% R=unique(R','rows')'; % comment this line if you run out of memory
% Decompose B = R*R' using singular value or LU decomposition
[L,U,p] = lu(R(k,:)'*R(k,:),'vector'); % LU decomposition
for j=1:nimgs
b=R(k,:)'*A(k,j);
% Obtain coefficients c which minimise least-square residuals
lower.LT = true; upper.UT = true;
c = linsolve(U,linsolve(L,b(p,:),lower),upper);
% Compute optimised reference image
optrefimages(:,:,j)=reshape(R*c,[ydim xdim]);
end
end

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%% Physical Constants
PlanckConstant = 6.62606957e-34;
PlanckConstantReduced = PlanckConstant / (2 * pi);
FineStructureConstant = 7.2973525698e-3;
ElectronMass = 9.10938291e-31;
GravitationalConstant = 6.67384e-11;
ProtonMass = 1.672621777e-27;
AtomicMassUnit = 1.66053878283e-27;
BohrRadius = 0.52917721092e-10;
BohrMagneton = 927.400968e-26;
BoltzmannConstant = 1.3806488e-23;
StandardGravityAcceleration = 9.80665;
SpeedOfLight = 299792458;
StefanBoltzmannConstant = 5.670373e-8;
ElectronCharge = 1.602176565e-19;
VacuumPermeability = 4 * pi * 1e-7;
DielectricConstant = 1 / (SpeedOfLight^2 * VacuumPermeability);
ElectronGyromagneticFactor = -2.00231930436153;
AvogadroConstant = 6.02214129e23;
%% Parameters
syms x y z theta lambda P wo wx1 wz1 wx2 wz2 I gamma real
% Define constants
lambda_val = 0.532; % µm
P_val = 1;
wo_val = 100;
% Set beam waists equal for simplicity
wx1 = wo; wz1 = wo;
wx2 = wo; wz2 = wo;
%% Rotation matrix and k-vectors
% Rotation matrix
R = @(theta) [1 0 0; 0 cos(theta) -sin(theta); 0 sin(theta) cos(theta)];
% Define rotated coordinates and k-vectors
k1 = @(theta) R(theta) * [0; 1; 0];
k2 = @(theta) R(-theta) * [0; 1; 0];
RotatedCoords1 = @(theta) R(theta) * [x; y; z];
RotatedCoords2 = @(theta) R(-theta) * [x; y; z];
%% Define E fields
k1vec = k1(theta);
coords = [x; y; z];
rot1 = RotatedCoords1(theta);
rot2 = RotatedCoords2(theta);
% Polarization vector
e_pol = cos(gamma)*[0; 0; 1] + sin(gamma)*[1; 0; 0];
E1 = sqrt((2 * P) / (pi * wx1 * wz1)) * ...
e_pol .* exp(1i * (k1(theta).' * coords)) * ...
exp(-(rot1(1)^2 / wx1^2) - (rot1(3)^2 / wz1^2));
E2 = sqrt((2 * P) / (pi * wx2 * wz2)) * ...
e_pol .* exp(1i * (k2(theta).' * coords)) * ...
exp(-(rot2(1)^2 / wx2^2) - (rot2(3)^2 / wz2^2));
Efield = simplify(E1 + E2);
%% Intensity expression
Intensity = simplify(1/2 * real(conj(Efield) .* Efield)); % 3-component
%% ================ Plot lattice =================== %%
% Define parameters
theta_val = 10 * pi / 180; % 10 degrees in radians
gamma_val = pi/2.0; % tilt of linear polarization
% Extract z-component of intensity at x = 0
Iplane_z = simplify(subs(Intensity(3), x, 0));
% Convert to function
Iplane_func = matlabFunction(Iplane_z, 'Vars', {y, z, theta, wo, lambda, P, gamma});
% Grid for y and z
[ygrid, zgrid] = meshgrid(linspace(-1000, 1000, 500), linspace(-100, 100, 300));
% Evaluate intensity
Ivals = Iplane_func(ygrid, zgrid, theta_val, wo_val, lambda_val, P_val, gamma_val);
% Normalization
Ivals = Ivals / max(Ivals(:));
% Plotting
figure(1)
clf
set(gcf,'Position',[50 50 950 750])
contourf(ygrid, zgrid, Ivals, 200, 'LineColor', 'none');
colormap('turbo');
colorbar;
% Preserve physical aspect ratio
pbaspect([1 1 1]); % Set plot box aspect ratio to 1:1:1
axis tight;
xlabel('y [µm]', 'FontSize', 12);
ylabel('z [µm]', 'FontSize', 12);
title(['I_{plane}(y, z) at x = 0, \theta = ' num2str(rad2deg(theta_val)) '^\circ'], 'FontSize', 14);
set(gca, 'FontSize', 12, 'Box', 'on');
%% ================ Plot Potentials of lattice =================== %%
% Find indices closest to zero in y and z grids:
[~, idx_y0] = min(abs(ygrid(1,:))); % y=0 along columns
[~, idx_z0] = min(abs(zgrid(:,1))); % z=0 along rows
% Cut along y at z=0:
% z=0 corresponds to row idx_z0, extract entire column idx_z0 in y direction
Iprop_cut = Ivals(idx_z0, :); % 1D array vs y
% Cut along z at y=0:
% y=0 corresponds to column idx_y0, extract entire row idx_y0 in z direction
Ivert_cut = Ivals(:, idx_y0); % 1D array vs z
% Extract corresponding y and z vectors
yvec = ygrid(1, :);
zvec = zgrid(:, 1);
% Plot -Iprop/2 along y
figure(2);
clf
set(gcf,'Position',[50 50 950 750])
plot(yvec, -Iprop_cut/2, 'LineWidth', 2);
title('Profile at x=0, z=0');
xlabel('y [\mum]');
ylabel('Depth');
grid on;
set(gca, 'FontSize', 12, 'Box', 'on');
% Plot -Ivert/2 along z
figure(3);
clf
set(gcf,'Position',[50 50 950 750])
plot(zvec, -Ivert_cut/2, 'LineWidth', 2);
title('Profile at x=0, y=0');
xlabel('z [\mum]');
ylabel('Depth');
grid on;
set(gca, 'FontSize', 12, 'Box', 'on');