CHAPTER 2 GEOMETRIC OPTICS Optics 311 Geometric Optics

CHAPTER 2 GEOMETRIC OPTICS Optics 311 - Geometric Optics 1

Imaging by an optical system • Every ray from O to I requires the same transit time isochronous. • The point O is the conjugate of point I. • In an ideal system, every ray from O pass through I. • Practical systems are non-ideal due to: 1. Scattering dimming 2. Aberrations distortion; no 1 -to-1 relationship 3. Diffraction sharpness (diffraction limited) Optics 311 - Geometric Optics 2

Reflection at a Spherical Surfaces http: //www. phy. ntnu. edu. tw/ntnujava/index. php? topic=48 Optics 311 - Geometric Optics 3

Thin Lenses Lensmaker’s equation Optics 311 - Geometric Optics 4

Reflection at a Spherical Surfaces Reflection (Mirrors) Cases Case 1 Case 2 Case 3 Refraction (lenses) Convex Concave Converging Diverging V-U-S V-U-L V-U-S R-I-L V-U-S R-I-S V-U-S Optics 311 - Geometric Optics 5

Reflection at a Spherical Surfaces Optics 311 - Geometric Optics 6

Refraction at a Spherical Surfaces Optics 311 - Geometric Optics 7

Refraction at a Spherical Surfaces Starting from Snell’s law What happens when R ? Optics 311 - Geometric Optics 8

Refraction at a Spherical Surfaces Example. . Optics 311 - Geometric Optics 9

Vergence and Refractive Power When distance is measured in meters. . The refracting power is measured in diopters Optics 311 - Geometric Optics 10

Vergence and Refractive Power When two thin lenses are in direct contact Optics 311 - Geometric Optics 11

Newtonian Equation for the Thin Lens Optics 311 - Geometric Optics 12

Cylindrical Lenses Spherical Lens (stigmatic) Cylindrical Lens (astigmatic) Optics 311 - Geometric Optics 13

ABERRATION Spherical Optics 311 - Geometric Optics 14

ABERRATION Coma Optics 311 - Geometric Optics 15

ABERRATION Astigmatism Circle of least confusion Optics 311 - Geometric Optics 16

ABERRATION Field curvature Optics 311 - Geometric Optics 17

ABERRATION Angular deviation of the wavefront destroying the linear relation between dimensions in object and image Distortion Optics 311 - Geometric Optics 18

THE INFLUENCE OF APERTURE STOPS Images can be improved by stops Distortion can be controlled by the correct positioning of the aperture stops Optics 311 - Geometric Optics 19

THE CORRECTION OF CHROMATIC ABERRATION Chromatic aberration: The spread of an image point over a range of colors WHY ? ? The power of a refracting surface depends on the wavelength Can be compensated for by combining lenses made of different materials Optics 311 - Geometric Optics 20