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S.M.Joshi College,Hadapsar Department of Physics Sub: Optics Dr.S.H.Pisal. Optics Types of lenses. Concave Lens. Convex Lens. Converging and diverging lenses. Why are the following lenses converging or diverging ?. Converging lenses. Diverging lenses. Converging and diverging lenses.
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S.M.JoshiCollege,HadapsarDepartment of PhysicsSub: OpticsDr.S.H.Pisal
OpticsTypes of lenses Concave Lens Convex Lens
Converging and diverging lenses Why are the following lenses converging or diverging? Converging lenses Diverging lenses
Converging and diverging lenses Why are the following lenses converging or diverging? Converging lenses Diverging lenses
Cardinal points of Optical System Optical System has six cardinal points: Pair of Focal Points : Pair of Principle Points : Pair of Nodal Points
Cardinal points and planes:1. Focal (F) points & Principal planes (PP) and points n nL n’ F1 H1 ƒ PP1 Keep definition of focal pointƒ
Cardinal points and planes:1. Focal (F) points & Principal planes (PP) and points n nL n’ F2 H2 ƒ’ PP2 Keep definition of focal pointƒ’
Lens Aberrations Aberrations fall into two classes: monochromatic and chromatic. Monochromatic aberrations are caused by the geometry of the lens or mirror and occur both when light is reflected and when it is refracted. They appear even when using monochromatic light, hence the name. Chromatic aberrations are caused by dispersion, the variation of a lens'srefractive index with wavelength. They do not appear when monochromatic light is use • Monochromatic Aberrations • Spherical • Coma • Astigmatism • Distortion • Radius of curvature • Chromatic Aberrations
Spherical Aberration Marginal and paraxial rays not coming to focus at a single point
Coma Aberration Object point is situated off the principal axis, the lens form comet like image in place of point object.
Astigmatism When object point is situated far off the principal axis, the lens form two mutually perpendicular lines separated by finite distance.
Distortion The variation in the magnification produced by a lens for different axial distances results in aberration called distortion Pin cushion distortion (c) Barrel shape distortion
Curvature of Field For extended object in the form of plane surface in front of lens Its image will not be flat one but will be curved surface called as curvature of field.
Chromatic aberration When white light after refraction through a lens form a number of coloured Images of different sizes at different positions. This defect is known as chromatic aberration. Longitudinal chromatic aberration (df) = - w x f Condition for achromatic combination = +