Intensity Distribution of 4 Slit diffraction grating using convolution

[doublemint]

Hi all,

I am trying figure out this diffraction problem.

I have to find the intensity distribution of a four slit fraunhofer diffraction grating using the convolution theorem. I can do the math and all...but I do not know how to start it! The only information I am given is the slits have a width of a = 10um and the impinging light has a wavelength of 633nm.
Since the slits have a defined width value, I cannot use the comb function and a rectangular function for my convolution. So, what functions should I be using??

Thanks,
DM

 

[aaa2]

A sum of rectangular functions. 4 of them. you can probably make a convolution with 4 delta functions and one rectangular function to create those.