Interferometers

[Music] hey welcome to yet another session in introduction to photonics so we started the last couple of lectures trying to appreciate the science of light in terms of ray optics initially we saw some examples of how ray optical principles can be used to design various elements like endoscope sand you are looking at

what happens when light goes through a prism and so on and then we said okay ray optics can get us so far but there are certain properties of light especially when it comes to explaining the wavelength and and phase of light we are not able to capture that using ray optics so we went on to looking at light

waves as sorry light as propagating in terms of waves and once we realize you know it can propagate as waves and it can accumulate face as it propagates we said okay two light waves can meet with each other and then you could have things like constructive and destructive interference so we looked at the example

of Young's double slit experiment through which we said okay when when two wavelets are generated secondary wavelets generated through the slits which are comprised comparable to the wavelength of light then they could interfere in the far field providing you know bright fringes at some points and dark fringes and some some other points

and so on and you had the opportunity to work on this last week you you did a hands-on experiment some of you following this online you saw a demo corresponding to this where you could see diffraction patterns and interference patterns from a single slit and a double slit and etc right so what we are going to go

towards this week is understand interference in a in a deeper sense okay we're going to first of all extend our discussion from a double slit to multiple slits and see what is the effect of that we will of course look at what is the practical example of a multiple slit type of interference and