DOI: 10.5281/zenodo.3582945
title: LiF data pack supporting "Observation of diffraction contrast in scanning helium microscopy"

description: All the experimental data from the paper is included in this data pack including both the images and the z scans. Images from the paper are presented in three different formats with filenames scan00*****: 1) .png file which is an unprocessed image of the raw data. <br> 2) .gwy file which is an unprocessed version of the data that can be opened in Gwyddion<br> 3) .mat file which contains all the measured data that can be opened in MATLAB The .mat file contains the most information and requires some explanation to easily understand.<br> The data is saved in a structure named meas, the key fields are as follows: meas.target - A matrix of the target position for each pixel, with a column for each of the x,y coordinates<br> meas.inputs - Input parameters used in the scanning program to collect the data<br> meas.initial_pos - Position of each the three stages at the start of the scan. The 3rd coordinate is the z scan and does not change throughout the scan<br> meas.data - A vector of the measured current at each pixel in Amps<br> meas.image - A matrix that represents the acquired image The remaining fields are explained at the bottom of the readme. The z scans are saved Z*****.mat and can be opened in MATALB.<br> The key variables in the data files are: z_position - Raw z coordinate of the positioner in nm<br> current_z - Measured current at each point in Amps<br> m - Horizontal scan gradient (approximately 1)<br> m2 - Vertical scan gradient (approximately 0)<br> step_pos - x coordiate at z_position=0<br> step_pos_v - y coordinate at z_position=0 The x,y position at each point in the scan can then be obtained from<br> x=step_pos + m*(z_position)<br> y=step_pos_v + m2*(z_position) <br> The true z distance between the pinhole and the sample in nm can be calculated from z=z_position-4295000 The included data in the pack contains: Images presented in the paper:<br> scan001357<br> scan001361<br> scan001398<br> scan001415 Z000006.mat - z scan of flat region<br> Z000008.mat - z scan of heavily distorted region<br> Z0000012.mat - z scan of lightly distorted region<br> Z000013.mat - z scan of HOPG z_scan_movie.avi - Video illustrating how the images vary with z<br> scan001401-scan001413 - Data to produce the video In addition, the analysis scripts have been included for reference. <br> The scripts can be used to regnerate the figures in the paper. <br> The remaining fields in the meas structure are:<br> meas.date_time - Start date and time of the scan<br> meas.type - Scan pattern of the image. Always raster_jump<br> meas.p1 - Unused pressure<br> meas.p2 - Unused pressure<br> meas.p3 - Unused pressure<br> meas.p_srce - Source pressure at the start of the scan<br> meas.p_diff - Differential stage pressure at the start of the scan<br> meas.p_smpl - Sample pressure at the start of the scan<br> meas.p_det - Detector pressure at the start of the scan<br> meas.N_dwell - Number of current measurements taken at each pixel<br> meas.comments - comments (unused)<br> meas.det_params - Detector parameters used in the scan<br> meas.labtemp - A vector of the labtemp at each pixel (unused)<br> meas.return_state - Error status <br>