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Analysis routine for Line-imaging VISAR (Velocity Interferometer System for Any Reflector) data
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VISAR Scripts

For a discussion of the theory, please visit my blog post


Run the analysis script in an iPython terminal. Click-and-drag the image (png format) in the terminal.

>>> %run
>>> time, velocity, analysis_params = analyze()

Load png Streak image
Drag and drop location into command prompt
path > /<Path>/smith.png

Select working data and reference

This will open up the PNG image in a matplotlib figure. The figure has event handeling enabled, and you will be propted to Select Working data from raw image by drawing a rectangle (red) on the figure by clicking and dragging. You must drag from the bottom-left to top-right.

Press enter in the terminal to select the region of data. You will then be propted to select a region of reference fringes, drag away from the start of the rectangle (green). Press enter in the terminal to confirm selection.

Select the fundamental frequency

A new window will open for you to select the fringe-spacing frequency of interest. Click on a location of the plot to select the minimum frequency (green), press enter (at the window focus, not the terminal), and select the maximum frequency (red). Press enter in the terminal to end selections.

Pick Etalon

A menu will prompt you to choose the VPF. The VPFs listed in this menu are determind my the JSON config file etalon_conf.json.

Pick an etalon thickness:

	[0]____________1e+03 mm________46.29 km s-1
	[1]____________2e+03 mm________23.14 km s-1
	[2]____________5e+03 mm________9.258 km s-1
	[3]________1.144e+04 mm________4.047 km s-1
	[4]__________1.5e+04 mm________3.086 km s-1
	[5]__________2.5e+04 mm________1.852 km s-1
	[6]__________4.5e+04 mm________1.029 km s-1
	[7]_________9.97e+03 mm________5.175 km s-1
	[8]_________2.53e+04 mm________2.039 km s-1
> 9
Enter custom vpf: 5.4603

Subtract Background (optional)

Enter "yes" in the terminal to subtract background fringes. You will be prompted to drag-and-drop a reference image. This will then be processed with the same selections you made to the data. (These parameters are stored in the ANALYSIS_PARAMS dictionary.

Take a line-out of the data

Using the click-and-drag technique, select a rectangle of interest (green) from the veloctiy map.

analyse() will now return time and velocity arrays from your selection, along with a dictionary of the parameters you selected during the analysis


You will then be propted to add fringe shifts, or invert the velocity trace

Recalling an old Analysis

Saving analysis parameters

At the end of the analysis, a analysis_param dictionary will be returned. Save this dictionary using the method call

save_parameters(analysis_params, name="name/of/file")

This will generat a pickle file which can be recalled later

Loading alaysis parameters

To recall an old analysis session, run the automation method with the pickle analysis_params passed as an argument


Cite this work

  doi = {10.5281/zenodo.2578671},
  url = {},
  author = {Hammel,  Ben},
  title = {bdhammel/line-visar-analysis: Initial release},
  publisher = {Zenodo},
  year = {2019}

B. Hammel. bdhammel/line-visar-analysis: Initial release, 2019.

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