Chapter 1 Mirrors, lenses and imaging systems (Chap. 24 page 593)

1. Chapter 1 Mirrors, lenses and imaging systems(Chap. 24 page 593) Dr. Haykel Abdelhamid Elabidi February 2014/1st-2nd weeks of RaT 1435

2. Units of Chapter 24 • The lenses • The power of a lens • The human eye • Optical defects of the eye

3. Lenses • A lens is a piece of transparent material that can focus a transmitted beam of light so that an image is formed. • Convergent lensisthickeratits center thanat the edge. • Divergent lensisthickeratitsedgethantatits center.

4. Lenses, focal distance A converging lens will refract parallel rays so that they meet or form an image at a focal point F’ beyond the lens. A diverging lens will bend the rays outward so that they appear to have come from a focal point F’ before the lens. The distance from the center to the focal point is called the focal distance f. it is positive for converging lenses and negative for diverging lenses.

5. Lenses, image formation • Light always goes from left to right • Real objects are to the left of the lens, and real images to the right • Virtual images are to the left of the lens, and virtualobjects to the right. • Fig 24.7 page 597 • sis the object distance (from the center of the lens to the object) • s’ is the image distance (from the center of the lens to the image)

6. Lenses, image formation

7. Lenses, image formation Example 24.4 page 599 A camera lens has a focal length of +0.1 m. (a) If the camera isfocused on a child 2 m from the lens, whatis the distance from the lens to the film? (b) If the child has a height of 1 m, how tallis the image on the film?

8. Lenses, image formation Example 24.6 page 603 A collector uses a lenswith focal length of 0.1 m to examine a stamp. Whatangular magnification isprovided by the lens?

9. The power of a lens, aberration

10. The power of a lens, aberration

11. Aberrations • In this subsection, we are going to see how the additivity of the powers can be used to treat a lens configuration designed to minimize aberrations. • No matter how perfectly spherical its surface, any lens suffers from various kinds of aberrations, which limit the sharpness of its images independently of diffraction effects. • Since the index of refraction of glass varies with the wavelength of the light, the focal length of a lens also varies with the wavelength.

12. Aberrations • Chromatic aberration: • When an object is illuminated with white light, if its image on a screen is in focus for one colour component, it will be slightly out of focus for the others. • Monochromatic aberrations: • aberrations occur for light of a single wavelength.

13. The human eye

14. The human eye

15. Optical defects if the human eye

16. Optical defects if the human eye: Myopia

17. Optical defects if the human eye: Myopia

18. Optical defects if the human eye: Myopia

19. Optical defects if the human eye: Hypermetropia

20. Optical defects if the human eye: Hypermetropia Solution example 24.13 page 624

21. Optical defects if the human eye: Astigmatism

22. Homeworks: Exercises 24.63; 24.64; 24.67; 24.68 Pages 628/629 Thank you for your attention See you next time Inchallah