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GEOMETRICAL OPTICS




Light

  • What is light
  • laws of reflection
  • Laws of Refraction
  • Dual nature of Light - 
  • particle nature of Light
  • wave nature nature of Light
  • speed of Light, 
  • wave length of Light 
  • frequency of light.
  • Fermats’ principle
  • laws of reflection
  • Laws of Refraction refraction at a plane surface using Fermats’ principle.




Refraction  of Light

  • Snell's law
  • refractive indices
  • relative and absolute refractive indices
  • total internal reflection
  • Critical angle 
  • refraction by plane parallel slab of glass
  • molecular basis of reflectively
  • Geometrical path length of ray
  • optical path length of ray
  • Concept of wave fronts & rays
  • concept of vergence
  • concept ofdivergence
  • concept ofconvergence



Spherical Surfaces 


  • Refraction by spherical surfaces
  • Refraction by convex surface  
  • Refraction by concave surface 
  • Derivation of vergence equation
  • focal points
  • dioptric power power 
  • image point
  • lateral & axial magnification
  • simple numerical




Lenses 

  • Thin Lens
  • Types of lenses
  • derivation of lens makers’ formula
  • thin lens vergence equation, 
  • equivalent focal length of two thin lenses separated by a distance & placed in contact
  • lateral magnification of thin lenses in contact
  • simple numerical
  • concept of reduced systems
  • Thick Lens- Cardinal points & planes
  • front & back vertex power
  • matrix theory in paraxial Optics to locate positions of cardinal planes
  • Different types of aberrations & their effects



Prisms

  • Prism
  • Dispersion of prism
  • reflecting prisms
  • prism diopters
  • Geometrical theory of optical fibers
  • Uses of optical fibers

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Lloyd's’ mirror experiment

Lloyd's mirror This is another method for finding the wavelength of light by the division of wavefront. Light from a slit So falls on a silvered surface at a very small grazing angle of incidence as shown in the diagram (Figure 1). A virtual image of So is formed at S1. Interference occurs between the direct beam from So to the observer (0) and the reflected beam The zeroth fringe will be black because of the phase change due to reflection at the surface.  Application An interesting application of this effect may be observed when a helicopter flies above the sea near a radio transmitter. The helicopter will receive two signals: (a) one signal directly from the transmitter and (b) a second signal after reflection from the sea As the helicopter rises the phase difference between the two signals will alter and the helicopter will pass through regions of maxima and minima. Lloyd's mirror Experiment Lloyd’s Mirror is used to produce two-source interference...
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Fresnel's Biprism

A Fresnel Biprism is a thin double prism placed base to base and have very small refracting angle ( 0.5o). This is equivalent to a single prism with one of its angle nearly 179° and other two of 0.5o  each. The interference is observed by the division of wave front. Monochromatic light through a narrow slit S  falls on biprism , which divides it into two components. One of these component is refracted from upper portion of biprism and appears to come from S1 where the other one refracted through lower portion and appears to come from S2. Thus S1 and S2 act as two virtual coherent sources formed from the original source. Light waves arising from S1and S2 interfere in the shaded region and interference fringes are formed which can be observed on the screen . Applications of Fresnel's Biprism Fesnel biprism can be used to determine the wavelength of a light source (monochromatic), thickness of a thin transparent sheet/ thin film, refractive index of medium etc. A. ...
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Point Source vs Extended Source

For a point source, the emitted light intensity or pointance is the same in all directions, or isotropic. It behaves according to the inverse square law. A flat surface that reflects or emits equal luminance in every direction from the surface is said to be a lambertian surface. For example, an evenly illuminated flat surface such as a sheet of paper is approximately lambertian in that the luminance that you see from any direction is essentially the same. The intensity or pointance from such a surface in any direction is proportional to the cosine of the reflected angle. Reflection from a surface can be complicated by surface roughness. For an ideal lambertian surface the reflection will follow the cosine law. The ray showing 50% is at the angle 30° from the surface where cos 60° = 0.5. An interesting aspect of lambertian reflection is that although the luminous intensity will be half as much at that angle, the visual area that your eye sees is also half as much, so the surface a...
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