Dispersion and Scattering and their characteristics

Dispersion and Scattering:

Refractive processes occur in the physical optics range, where the wavelength of light is the same as at other distances, as a form of scattering. Thomas scattering is one of the simplest types of scattering which takes place when an electromagnetic wave is deflected by single particles. In the limit of Thomson scattering, in which the wave-like nature of light is apparent, light is independent of frequency, in contrast to Compton scattering, which is a frequency-dependent and strictly quantum mechanical process, involving the nature of light particles.

The process on which the elastic scattering of light occurs by many particles that is very much smaller than the wavelength of light is known as Rayleigh scattering on the other hand the similar process in which the scattering of particles is done that is larger is similar to the wavelength is known as Mie scattering with the Tyndall effect being a commonly observed result.

Raman Scattering

Raman scattering could also happen with the small proportion of the light scattering from atoms or molecules where the excitation in the atoms and molecules creates a change in the frequency. Brillouin scattering is a process that occurs when there is a change in the frequency of light due to small changes in time and the movement of dense material. The process of dispersion takes place when the light wave of different frequencies has different phase velocities, either due to material properties or to the geometry of an optical waveguide (known as waveguide dispersion). A decrease in the index of refraction with increasing wavelength is the most familiar form of dispersion, which is observed in the most transparent materials. This is known as “normal dispersion”. The refraction index can increase the wavelength in the wavelength ranges where the medium has significant absorption. This is known as “anomalous dispersion". Some manufacturers design precision prisms and custom optical lenses which are used for special purposes and for the manufacturing of these optics, precision optical manufacturing process is performed.

The phenomenon of separation of colors through a prism is an example of normal dispersion. As per Snell’s law, the light at the surface of the prism incident at an angle of Θ to the normal will get refracted by making an angle of arcsin(sin(Θ/n)). Therefore, it is observed that the blue light is bent more because of its high refractive index as compared to the refractive index of red light, which eventually gives us the famous rainbow pattern.