collimator

This is a collection of scripts to design 3D printed radial ("Soller slit") collimators.

Prerequisites

• Python (all components should now work with Python 3)
  • numpy
  • scipy
  • vapory (to allow raytracing with POV-Ray in Python)
• FreeCAD 0.18
• POV-Ray 3.7.0.8
• stltools

Steps to design a Soller collimator

1. Design your grid

Edit the script designer/soller.py to meet your requirements. Most parameters are as in the earier Mathematica vesion of the script.

• format should usually be json
  • scad is retained as an option to produce output compatible with OpenSCAD, which can allow a quick preview of the model without having to render
• part should be 0 unless you want to generate only a subset of the grid walls (this can be used as part of the process to facilitate blob-free printing)

Run the script to produce the RadialCollimatorBox and RadialCollimatorGrid files.

2. Create the 3D model

1. Open Collimator.FCMacro in FreeCAD.
   • Ensure the paths to your .json files are correct
   • Edit the relevant lines to set the desired wall thicknesses
2. Create a new empty document
3. Execute the macro in the editor

3. Test the model using raytracing

1. Use stl2pov from stltools to produce a .inc file
2. Use the raytracing/povray.py script, in particular its scene function to render what an image would look like on an area detector; examples can be found in the script. It is recommended to use an interactive Python shell while working with this
   • Always be sure to include the auto_camera_angle=False option, otherwise the view will not be as you intended

4. Print the grid

Your mileage may vary, depending on the material used and the print options selected.

Further reading

• A novel 3D printed radial collimator for x-ray diffraction by S. Kowarik, L. Bogula, S. Boitano, F. Carlà, H. Pithan, P. Schäfer, H. Wilming, A. Zykov and L. Pithan