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🔄 Centering your sample

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titleFor Samples smaller than the FOV:

Method 1: Calculating the shift

  1. GTS Rotation 0°

  2. Draw annotation circle same size as sample/feature of interest.

  3. Configure to be at Y 1280 and X 1080.

  4. Move sample/feature using X step to recover it in the centre of circle.

  5. GTS Rotation 90

  6. Move sample/feature using Z step to recover it in the centre of the circle.

  7. Check positions at 180 and 270 and with full rotation (0-360) to ensure feature remains centered.

image-20240628-144646.pngImage Removed

Method 2: Circle method (Easier, slightly less precise)

  1. GTS Rotation 0°

  2. Draw annotation circle same size as sample/feature of interest.

  3. Configure to be at Y 1280 and X 1080.

  4. Move sample/feature using X step to recover it in the centre of circle.

  5. GTS Rotation 90

  6. Move sample/feature using Z step to recover it in the centre of the circle.

  7. Check positions at 180 and 270 and with full rotation (0-360) to ensure feature remains centred.

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titleFor Samples larger than the FOV:

For Samples larger than the FOV:

  1. Mount sample on GTS

  2. Set GTS Rotation to 0 degrees

  3. Use GTS X to move the specimen until one side aligns with the edge of the FOV.

  4. Record the GTS X position

  5. Use GTS X to move the sample in the opposite direction until the other edge aligns with the FOV.

  6. Record the 2nd GTS X Position.

  7. Calculate the centre of these two points and enter the value into GTS X.

  8. Set GTS Rotation to 90 degrees.

  9. Repeat steps 3 to 7 using GTS Z motion.

  10. Once sample is centred along X and Z axis the sample will be on the COR.

Optimising your imaging quality

  • No of projections is Pixel dimensions x π/2

  • Flat field ideally should be 35K count, contrast between brightest and darkest feature in sample should be around 20%

  • For stitching multiple tomography scans leave at least 10-20% overlap.

Image Guided Diffraction

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titleUsing reconstructed images to guide diffraction
  • Notebook for calculating X,Y Theta coordinates from pixel X,Y in reconstruction

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