Page History

...

res = rb.subtract_bkgd(nda)

Polarization correction

• For good statistical precision of the background averaging 2-d bins should contain large number of pixels. Binning artifact in some places However large bins produces significant binning artifacts whech are seen in resulting image.
• Photon The main reason for angular bins is a variation of intensity with angle due to polarization effect. The beam polarization effect is observed in the image with single angular bin can be eliminated with appropriate correction.
  Then, radial background can be estimated for a single angular bins (ring-shaped radial bins). One could eliminate this effect by modulation of the background sample using polarization correction:

pf = polarization_factor(rb.pixel_rad(), rb.pixel_phi(), z)
res = rb.subtract_bkgd(nda * pf)

For z=1m we get polarization correction factor, corrected data (water-ring) sample, and background subtracted data :as follows.

Effect of polarization is somehow accounted, but most likely the sample-to-detector distance 1m is not correct.

...