diff --git a/Tex/experiment.tex b/Tex/experiment.tex index 622ee41..872d34c 100755 --- a/Tex/experiment.tex +++ b/Tex/experiment.tex @@ -203,7 +203,12 @@ \subsection{Preprocessing} \paragraph{Crystal orientation} -For determining the relative orientation of the crystal with regards to the detector, Kossel lines as described in \fref{chap:kossel} can be used. A semi-automatic alignment program was developed (\fref{fig:kosselfit}) and used the find the crystal orientation (\fref{tab:kosselfit}). As initial parameters, 5.65\,\AA\, lattice constant, 9.25\,keV energy and 800\,px detector distance and the result of a simple 2D cubic fit for the values of the translational shift were used. +For determining the relative orientation of the crystal with regards to the detector, Kossel lines as described in \fref{chap:kossel} can be used. A semi-automatic alignment program was developed (\fref{fig:kosselfit}) to aid with the procedure: + +For each sample, the images are split into sets of 5000 shots and (after filtering for hot pixels and cutting bellow a noise threshold of 2\,keV), the mean is taken. To better distinguish the Kossel lines from uniform fluorescence, a Gaussian blurred version ($\sigma$=20\, px) is subtracted. Kossel lines are identified visually and the local maxima in the 20x20\,px surrounding block of a selected Kossel line are considered as points on the Kossel line. A least-square regression is performed to minimize the sum of the distances of identified points from Kossel lines by varying the rotation angles and detector translation. +As initial parameters, a 5.65\,\AA\, lattice constant, 9.25\,keV energy and 2800\,px detector distance and the result of a 2D cubic fit to the fluorescence background for the values of the translational shift are used. + +The results are shown in \fref{tab:kosselfit} as mean over the sets for each sample and maximum deviation from the mean as an error estimation. \begin{figure} \centering \includegraphics[width=0.8\linewidth]{images/kosselfit.png} @@ -211,6 +216,41 @@ \subsection{Preprocessing} \label{fig:kosselfit} \end{figure} +\begin{figure} + \centering + \begin{subfigure}{0.7\textwidth} + \includegraphics[width=\linewidth]{images/kossel_gaas.png} + \caption{Mean images after background subtraction for sample 1 (left) and sample 2 (right)} + \end{subfigure} +\\ + + \begin{subfigure}{0.35\textwidth} + \includegraphics[width=\linewidth]{images/kossel_gaas1.pdf} + \caption{Indexed lines on sample 1} + \end{subfigure} +\hspace{0.2cm} + \begin{subfigure}{0.35\textwidth} + \includegraphics[width=\linewidth]{images/kossel_gaas2.pdf} + \caption{Indexed lines on sample 2} + \end{subfigure} + \caption[Kossel lines on GaAs samples]{Kossel lines on GaAs samples after background subtraction (a) and the indexed lines overlaid in the determined orientation (b and c).} +\end{figure} + +\begin{table}[] + \caption{Results of the Kossel line analysis} +\begin{tabular}{llllllll} + \hline + Sample & \multicolumn{2}{l}{Translation} & \multicolumn{3}{l}{Rotation} & Detector Distance & \\ + & x in mm & y in mm & yaw & pitch & roll & in mm & \\ + \hline + GaAs 1 & 1.4$\pm$0.2 & 6.4$\pm$0.4 & -0.4°$\pm$0.2° & 0.1°$\pm$0.2° & 1.5°$\pm$0.2° & 141.7$\pm$0.8 & \\ + GaAs 2 & 1.3$\pm$0.2 & 5.8$\pm$0.3 & -0.2°$\pm$0.3° & 0.1°$\pm$0.2° & 46.1°$\pm$0.1° & 139.9$\pm$0.8 & \\ + \hline +\end{tabular} + + \label{tab:kosselfit} +\end{table} + \subsection{Reconstruction} @@ -226,17 +266,4 @@ \subsection{Imaging Crystals} -\begin{table}[] - \caption{Results of the Kossel line analysis} - \begin{tabular}{lllll} - \hline - Sample & Initial Translation & Initial Rotation & Energy & Rotation \\ - & x,y in pixels & Euler angles x,y,z & in keV & Euler angles x,y,z \\ - \hline - GaAs 1 & & & & \\ - GaAs 2 & & & & \\ - \hline - \end{tabular} -\label{tab:kosselfit} -\end{table} diff --git a/Tex/images/kossel_gaas.png b/Tex/images/kossel_gaas.png new file mode 100644 index 0000000..9326517 Binary files /dev/null and b/Tex/images/kossel_gaas.png differ diff --git a/Tex/images/kossel_gaas1.pdf b/Tex/images/kossel_gaas1.pdf new file mode 100644 index 0000000..320b00f Binary files /dev/null and b/Tex/images/kossel_gaas1.pdf differ diff --git a/Tex/images/kossel_gaas2.pdf b/Tex/images/kossel_gaas2.pdf new file mode 100644 index 0000000..eea6367 Binary files /dev/null and b/Tex/images/kossel_gaas2.pdf differ