The Fraunhofer diffraction equation and also the Fresnel diffraction equation predicts that the distance of the single slit to the observation screen is the only thing that defines that pattern.
Subsequently, the zero-order fringe is always the maximum for all the wavelengths in the far-field.
My experiments show that this is not correct. However, the main important thing is the refractive index of the barriers respect with the refractive index of the medium.
Subsequently, the zero-order fringe can be the maximum for the long-wavelength and destructive for the short-wavelengths in the far-field.
DOI: 10.13140/RG.2.2.23269.55527
Hmm. I don't know anything about this: " Subsequently, the zero-order fringe can be the maximum for the long-wavelength and destructive for the short-wavelengths in the far-field".
What I do know is that lines symmetrically radiating away from the center and strongest signal when using a Jelley refractometer were attributed to "edge diffraction". But I have come to believe that they are more probably due to consonant harmonic resonances between the liquids and the solids (prism glasses) they contact.
Stephen Arthur Langford Dear Stephen,
The Fraunhofer diffraction equation predicts that the maximum intensity of light appears at the zero-order fringe on the optical axis in the far field
But in my experiments, I saw that if the refractive index of the barriers are less than the medium then the Fraunhofer diffraction equation is not valid and the zero-order fringe can appear in different way based on the ratio of the refractive indices of the barriers and the medium.
This is the result for a glass single slit diffraction in the medium n1.6 and slot width 50 μm.
As you may see at this image,
- The zero-order fringe is Max for 650nm
- The first-order fringes in either side are Max for 520nm
- The zero-order is destructive for the 450nm
The Diffraction of a Single Slit with Transparent Barriers in Mediums with different Refractive Indices
DOI: 10.13140/RG.2.2.23269.55527
LicenseCC BY-NC-ND 4.0
Interesting, @ Farhad Vedad! :-) Would be interesting to see how patterns vary in a plane defined across the visible spectrum and at various slot widths within practicable bounds; over variable medium RIs and variable substrate RIs.
Stephen Arthur Langford
thank you Stephen! Could you please take a time and have a look at the paper? It’s available for download either.
however, I am still developing it.
I'm not sure what " It’s available for download either" means, Farhad. I gather that the paper is still being written. I've had one of those for some years. :-/ I don't see a link to it. I'm willing to look at it, but details related to the Fraunhofer diffraction equation are beyond my immediate expertise. No promises I'll be able to say anything useful. :-)
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