- #1
py_engineer
- 12
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Hi,
I am a bit confused regarding using FFT to calculate the 1D single slit diffraction pattern.. Let's take the simple setup shown here:
http://electron9.phys.utk.edu/optics421/modules/m6/images/sslit.gif"
If I wanted to do a quick calculation using Matlab, I would create a 1xN matrix of zeros everywhere, and 1 in the middle wherever the slit is located. Then I can simply use the fft function from Matlab to get the diffraction pattern.
But what I really want to know is the diffraction pattern as a function of x (vertical x-axis) and determine the actual spot size of the central beam for example.
Let's say that I decide that the slit matrix at index 1 corresponds to x=-1 mm, slit matrix at index N corresponds to x=1 mm, and the slit is actually located between -0.1 mm and 0.1 mm (whatever indices these correspond to). Is there a correspondence in the x values for the fft of the slit? Does the value of the fft of the slit at index 1 corresponds to its value at x=-1 mm? Or how does it work?
Sorry for the very confusing message.. I hope someone can help.
Thanks!
I am a bit confused regarding using FFT to calculate the 1D single slit diffraction pattern.. Let's take the simple setup shown here:
http://electron9.phys.utk.edu/optics421/modules/m6/images/sslit.gif"
If I wanted to do a quick calculation using Matlab, I would create a 1xN matrix of zeros everywhere, and 1 in the middle wherever the slit is located. Then I can simply use the fft function from Matlab to get the diffraction pattern.
But what I really want to know is the diffraction pattern as a function of x (vertical x-axis) and determine the actual spot size of the central beam for example.
Let's say that I decide that the slit matrix at index 1 corresponds to x=-1 mm, slit matrix at index N corresponds to x=1 mm, and the slit is actually located between -0.1 mm and 0.1 mm (whatever indices these correspond to). Is there a correspondence in the x values for the fft of the slit? Does the value of the fft of the slit at index 1 corresponds to its value at x=-1 mm? Or how does it work?
Sorry for the very confusing message.. I hope someone can help.
Thanks!
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