Question on Diffraction and interference.

[brat-sampson]

I was set a problem describing a series of 6 slits, spacing of 0.4mm and diffracting light of wavelength 600nm onto a screen 4m away. I had to graph the intensity across the screen. Now I managed that ok, but then it wants to now how the resulting graph would change if the slits had finite width 0.15nm.

Now, the problem for me is that although I get the principle (that the pattern I have already will be mapped onto the overall diffraction pattern) I have no real idea how to go about combining the many many formulae that seem to be out there to find the actual pattern.
Any help would be much appreciated.

 

[Edgardo]

Welcome to Physicsforums brat-sampson,

how did you calculate the pattern in the first case? Maybe you could use the Fraunhofer approximation, that is described in the book "Optics" by Eugene Hecht. What you do there is calculate a Fourier integral. Use a program like Mathematica. I didn't check, but maybe you can also calculate it by hand.