[Numpy-discussion] Horizontal lines in diffraction image (NumPyFFT)

Nadav Horesh nadavh@visionsense....
Sat Aug 9 10:39:33 CDT 2008

I run your code, and the results seems to me realistic, similar to what I got long back ago --- I do not see artefacts. You may try a more elaborate approach (vector field propagation) using camfr (sf.net/projects/camfr).


N.B. I tried to attach the image I got b y running your script, but I was too big to for this mailing list.

-----הודעה מקורית-----
מאת: numpy-discussion-bounces@scipy.org בשם Matthias Hillenbrand
נשלח: ו 08-אוגוסט-08 07:38
אל: numpy-discussion@scipy.org
נושא: Re: [Numpy-discussion] Horizontal lines in diffraction image (NumPyFFT)

today I found time to do concentrate on the proposed zero padding.

My Gaussian beam and the lenses have a diameter of approximately 2^16
array elements while the total array has a size of 2^18. The absolute
value of the Gaussian beam multiplied by the lenses converges to zero.
Out of this reason I assume that zero padding is not the reason for
the horizontal lines. I also inreased the amount of zero padding by
the factor of 4 but the horizontal lines were still present. Could
something like a difference in the calculation precision (complex
numbers) be the reason for the difference between Octave and Numpy?

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