A study of optics and waves
Figure v shows an example with water waves, and figure w with light.
Types of optics
I have arbitrarily chosen to take a snapshot of the pattern at a moment when the waves emerging from the slit are experiencing a positive peak. In some ways it might have been more appropriate to insert this chapter after section 6. The structure of a crystal, for example, can be determined from its x-ray diffraction pattern. Hooke himself publicly criticised Newton's theories of light and the feud between the two lasted until Hooke's death. This general approach to wave motion was used by Richard Feynman, one of the pioneers who in the 's reconciled quantum mechanics with relativity. The law of refraction says that the refracted ray lies in the plane of incidence, and the sine of the angle of refraction divided by the sine of the angle of incidence is a constant: sin. Since Huygens' principle is equivalent to the principle of superposition, and superposition is a property of waves, what Huygens had created was essentially the first wave theory of light. So far this book has discussed the interaction of light waves with matter, and its practical applications to optical devices like mirrors, but we have used the ray model of light almost exclusively. With many propagators including Democritus , Epicurus , Aristotle and their followers, this theory seems to have some contact with modern theories of what vision really is, but it remained only speculation lacking any experimental foundation. It was developed when researchers observed phenomena that the other two models could not explain. Energy lost by an electron e as it drops to a lower energy state can be radiated as a photon. In double-slit diffraction the application of Huygens' principle is visually convincing: it is as though all the sets of ripples have been blocked except for two.
The width of each slit is fairly big compared to the wavelength of the light. He summarized much of Euclid and went on to describe a way to measure the angle of refractionthough he failed to notice the empirical relationship between it and the angle of incidence. We will come back to the same ideas later using light.
Other colours such as brown, grey, purple, etc, are as much psychological and physiological in origin as physical. Why are computer chip manufacturers investing billions of dollars in equipment to etch chips with x-rays instead of visible light?
Waves and optics pdf
In optics, it typically consists of integrating ray-estimated field over a lens, mirror or aperture to calculate the transmitted or scattered field. In the late s and early s, Isaac Newton expanded Descartes' ideas into a corpuscle theory of light , famously determining that white light was a mix of colours which can be separated into its component parts with a prism. The scale of the drawing is such that a wavelengths is one cm. All the angles are the same. Diffraction can also be a bad thing. Since Huygens' principle is equivalent to the principle of superposition, and superposition is a property of waves, what Huygens had created was essentially the first wave theory of light. By understanding diffraction, one can learn how a telescope must be designed in order to reduce this problem essentially, it should have the biggest possible diameter. If you hold three fingers out in the sunlight and cast a shadow with them, either wave optics or ray optics can be used to predict the straightforward result: a shadow pattern with two bright lines where the light has gone through the gaps between your fingers. It is the most complex model of the three, and it includes the theory of both the Electromagnetic Wave Optics model and the Ray Optics model. Water waves - Water waves or ripples carry energy from one place to another. But the distance traveled does not have to be equal in order to get constructive interference. As discussed in subsection There are two ways in which restriction 2 might commonly be violated. Hardly ever have we explicitly made use of the fact that light is an electromagnetic wave. The waves travel different distances to get to the same point in space, n.
In radiothis approximation is used to estimate some effects that resemble optical effects. To learn more, check out the discussion of the Physical Optics branch.
A diffraction pattern formed by a real double slit. A photon is the smallest possible particle of electromagnetic energy. Woolf The Electromagnetic Wave Optics model, which considers EM Rad to have the form of waves, was developed to explain phenomena not predicted by the Ray Optics model. The circular rings around the bright stars are due to single-slit diffraction at the mouth of the telescope's tube. It was developed when researchers observed phenomena that the other two models could not explain. We will then be in a position to consider a number of phenomena in which the wave properties of light are important. Diffraction can also be a bad thing. The waves travel different distances to get to the same point in space, n. What would influence the choice of wavelength Note how similar are the distances traveled by the group of 7 rays, indicated with a bracket, that come closest to obeying the principle of least time. Rays are a simplified way of thinking about waves: they have direction but no phase, so one ray cannot interfere with another, and they are drawn normal to the propagating wavefront. Optics is the study of light and its uses. Although Newton's criticisms were fair enough, the debate also took on the overtones of a nationalistic dispute between England and continental Europe, fueled by English resentment over Leibniz's supposed plagiarism of Newton's calculus. Newton wrote a book on optics, and his prestige and political prominence tended to discourage questioning of his model.
Thus, almost none of the wave energy delivered to point B goes by these longer paths. The waves travel different distances to get to the same point in space, n.
This is because the slits are fairly big compared to the wavelength of the light being used. In subsection 0.
The circular rings around the bright stars are due to single-slit diffraction at the mouth of the telescope's tube.
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