Coherence

[Music] the last couple of lectures we've been looking at the wave properties of light and so we defined the concept of face of a light wave and then based on the face of the light way we have said okay light waves go through interference phenomena and through that you know by looking at

constructive and destructive interference interference we've been looking at how light tends to be brighter at certain spots and not so bright at other spots so we took the example of Young's double slit experiment and then we extended through multiple slits and then we came to the conclusion that when you go for multiple slits more number of

interfering sources you have more constrained interference criteria which provides you much better selectivity in the response and so we had taken the specific example of wavelength selectivity but in general Phi is given by two PI over lambda D sine theta so even for a constant wavelength you can say that spatially when you look at the

interference pattern the spatially the interference pattern is going to be much more sharper when you consider multiple sources of interference and we're going to be looking at some examples of course we looked at an example of compact disc last in the last lecture so we said okay the CD has multiple grooves which

essentially provide you this interference criteria so you can separate out colors and that actually is a subset of larger you know class of components called diffractive components so just the principles that we have looked here in terms of multiple slits can be extended to having optical components which are called diffractive components diffractive optics which