$diffraction vs refraction color$ $diffraction vs refraction color$ $diffraction vs refraction color$

Eventually, continuing this process of adding walls and filling (densely) with holes, one finds that we need to sum over an infinite number of light paths as depicted in bottom left panel of figure 2 even in the limit where is no wall anymore. One can add another wall and even more holes in these walls and yet again observe what would the paths over which one would have to sum to get the total light intensity at point M. Now, starting from the double slit experiment, one can try to add another wall with two holes in it and see what those light paths look like (top right panel of figure 2). Incindentally, the light ray picture and its optical length is still very useful when looking at interferences and it is common to represent them explicitly in a graphical way. This is illustrated by the well known experiment of Young's slits (depicted in the top left panel of the next figure). Now, this picture of single light ray taking the shortest path as such is not enough to explain, as far as I know, the phenomenon of diffraction.Īs someone else said in his answer, we need to account for the fact that a proper theory of light should be looking at the square of an amplitude which arises from the wave nature of light. This follows from Fermat's principle of shortest path followed by the light from one point to another that can be depicted by the following drawing We all kind of know that in air or vacuum, light travels (whatever that means) in straight line from a source point $S$ to an observation point $M$. When it comes to light phenomena, there are different ways to comprehend them: we can use a wave picture (Hyugens-Fresnel), we can use the most modern picture we have (QED) or we can use something a bit more intermediate which is the picture of light rays travelling from one point to another.

$diffraction vs refraction color$

My answer will be quite close to that of PhotonicBoom although a bit more graphical. If we make the slit bigger, and make the wavelength bigger by the same amount, then the difference in distance between the sources is greater, but the rate of change in the wave function is slower, so the phase difference between the two extremes of the slit is the same.īut, if we just make the wavelength smaller, and leave the slit the same, the rate of change in the wave function is faster, which is equivalent to making the slit bigger without changing the wavelength.

$diffraction vs refraction color$

Well, changing the wavelength is equivalent to changing the size of the slit. The significance of the size of the slit is apparent, right? If the slit is wider, then when viewed from some direction slightly off center, the phase difference from the left-most source and the right-most source will be greater, because the difference in distance between them is greater. Now, the number of these point sources there are, and the maximum difference in phase between them, is a function of the size of the slit, obviously. If you look closely at this image, it appears it was generated by an approximation of four point sources in the slit. Depending on your position, the point sources interfere constructively or destructively, and this is what yields the diffraction pattern. They are, really, but since they are not at equal distances to you, the radiation from each is delayed by a different amount. However, if you move a bit to the side, then all those point sources aren't in phase. If you are looking straight down the slit, then all those point sources are in phase. Think of diffraction like this: if you have a plane wave incident on a slit, then you can think about the space in the slit as being a line of infinitely many point sources that radiate in phase. Why will a blue ray bend lesser than a red ray through a slit of the size a little bigger than the wavelength of the blue ray?ĭon't think of bending.

$diffraction vs refraction color$

Diffraction vs refraction color