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WEL-COME

Learn about optical interfaces, paraxial rays, and the significance of focal, principal, and nodal points in optical systems as explained through Gaussian optics. Understand the properties of principal planes and points.

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WEL-COME

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  1. WEL-COME Presented By Dr. MORE SURENDRA Associate professor Department of Physics, YashwantraoChavanMahavidyalaya, Tuljapur

  2. CARDINAL POINTS In this chapter we studying about -Focal points -Principal points -Nodal points

  3. OPTICAL AXIS • An optical axis is a line along which there is some degree of rotational symmetry in an optical system. • The optical axis is an imaginary line that defines the path along which light propagates through the system. • For a system composed of simple lenses and mirrors, the axis passes through the center of curvature of each surface, and coincides with the axis of rotational symmetry.

  4. OPTICAL INTERFACE • The boundary separating 2 different optical media. • When light strikes an interface, some is reflected, some is transmitted through the interface and some is absorbed

  5. CARDINAL POINTS • The analysis of an optical system using cardinal points is known as Gaussian optics, named after C F Gauss • For an optical lens system - characteristics are defined by its "cardinal points” • Cardinal points consist of three pairs of points located on the optical axis of a rotationally symmetric, focal, optical system. • These are: • 1. FOCAL POINTS • 2. PRINCIPAL POINTS • 3. NODAL POINTS

  6. PARAXIAL RAYS • The rays extremely close to the optical axis are called paraxial rays • A refracting surface that is sufficiently close the optical axis treated as flat surface.

  7. Continue

  8. CARDINAL POINTS • The analysis of an optical system using cardinal points is known as Gaussian optics, named after C F Gauss • For an optical lens system - characteristics are defined by its "cardinal points” • Cardinal points consist of three pairs of points located on the optical axis of a rotationally symmetric, focal, optical system. • These are: • 1. 2 FOCAL POINTS • 2. 2 PRINCIPAL POINTS • 3. 2 NODAL

  9. FOCAL POINTS & PLANES • The Front Focal Point of an optical system has the property that any ray that passes through it will emerge from the system parallel to the optical axis. • The Back Focal Point of the system has the reverse property i.e. rays that enter the system parallel to the optical axis are focused such that they pass through the back focal point. • The Front And Back Focal Planes are defined as the planes, perpendicular to the optic axis, which pass through the front and back focal points.

  10. Continued

  11. PRINCIPAL PLANES & POINTS • The two Principal Planes have the property that a ray emerging from the lens appears to have crossed the rear principal plane at the same distance from the axis that ray appeared to cross the front principal plane, as viewed from the front of the lens. • Lens can be treated as if all of the refraction happened at the principal planes. • The principal planes are crucial in defining the optical properties of the system, e.g. distance of the object and image from the front and rear principal planes that determines the magnification of the system. • The Principal Points are the points where the principal planes cross the optical axis.

  12. Continued

  13. PRINCIPAL PLANES • If the medium surrounding the optical system has a refractive index of 1 (e.g., air or vacuum), then the distance from the principal planes to their corresponding focal points is just the focal length of the system. • In the more general case, the distance to the foci is the focal length multiplied by the index of refraction of the medium. • For a thin lens in air, the principal planes both lie at the location of the lens. • For a real lens the principal planes do not necessarily pass through the centre of the lens, and in general may not lie inside the lens at all.

  14. NODAL POINTS • The front and rear nodal points have the property that a ray aimed at one of them will be refracted by the lens such that it appears to have come from the other, and with the same angle with respect to the optical axis. • The nodal points therefore do for angles what the principal planes do for transverse distance. • Rays pas through them non deviated. • If the medium on both sides of the optical system is the same (e.g., air), then the front and rear nodal point coincide with the front and rear principal points, respectively.

  15. Continued

  16. H1 H2 B F2 F1 P2 P1 N2 N1 R

  17. Continued

  18. THANK’S

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