Geometrical Optics: Mirrors, Reflection, and Refraction

1. HW #2, Due Sep. 7 Chapter 2 P7, P12, P16, PH1, PH2

2. Lecture 5 (chapter 2 continued) • Quick Review: • Geometric Optics (Rays) • Shadows • Pinhole Camera • Laws of Reflection • Mirrors (plasma frequency) • This Lecture: • More on mirrors • Sub Sun and Sun Pillars • Multiple Reflection • Refraction ……

3. Geometrical Optics (Chapter 2) When objects are much larger than the wavelength Light Rays (Ray Optics)

5. Pinhole Camera *Pinhole Camera http://www.techxhome.com/lightsite/optics/pinholes/pinhole.html

6. i r I R air glass or mirror Law of Reflection N • Reflected ray (R ) lies in the plane defined by incident ray (I) and surface normal (N) • R makes an angle r that is equal to incident angle I. • R lies on the opposite side of of N as incident ray I

7. Mirrors Why metals reflect light? Why do they appear certain color? Why can we listen to radio stations far away? (plasma frequency) • Silvered and half-silvered mirrors • First-surface and second-surface mirrors *Oscillating Charge Field http://www.colorado.edu/physics/2000/applets/fieldwaves.html

8. Grazing Incidence Reflection (glass windows, water surfaces, waxed floors, etc.) • Reflectivity (how much is reflected?)

9. Who sees me in the mirror?! (field of view) Simply apply law of reflection and trace the rays…

10. Sun Pillars and Sub Suns

11. Ice Crystals

12. Sub Sun A bright subsun looking downwards from 11,000m over Italy, late afternoon 18th July 1995. The halo was intermittently visible over the southern and central parts of the country covered by a thin cirrus sheet. The halo elongated and contracted as the tilts of the plate crystal mirrors changed. Reflections from lakes and rivers shine through the cloud. Video by Les Cowley.

13. Sub Sun

14. http://www.members.tripod.com/~regenbogen/englisch/atlas.htm

15. Sun Pillar

16. Multiple ReflectionsExample: Second Surface Mirrors

17. Corner Reflectors Demo: multiple reflections in the hinged mirror

18. RefractionRecall: light velocity= c/n *Refraction 1 http://microscopy.fsu.edu/primer/java/refraction/index.html http://wigner.byu.edu/LightRefract/LightRefract.html http://www.techxhome.com/lightsite/optics/refraction/boyFish.html Fish Tank

20. Examples Material Refractive Index (n) Air 1.0003 Water 1.33 Glycerin 1.47 Immersion Oil 1.515 Glass 1.52 Flint 1.66 Zircon 1.92 Diamond 2.42 Silicon 4

21. Law of Refraction N i I n1 Air (for example) glass or water or … n2 R r • The Refracted ray (R ) lies in the plane defined by Incidence ray (I) and surface Normal (N) • The Refracted ray (R ) lies on the opposite side of N as the incident ray I, and • The Refracted ray (R ) makes an angle r that satisfies the Snell’s law: (for small angles)

22. Snell’s Law (exact) c a 

23. Total Internal Reflection *Total Internal Reflection (Optical Fiber) http://www.techxhome.com/lightsite/optics/refraction/fiberOptic.html

24. Total Internal Reflection

25. Prisms as perfect reflectors: See Fig. 2.56 in the Text

26. Next Refraction in Nature Mirages, Rainbows, Halos, Sun Dogs….

27. sunset MiragesandAtmospheric Distortions mirage

28. Mirage

29. Dispersion Refractive Index varies with Wavelength : n() Dispersion in a prism * Prism Refraction http://microscopy.fsu.edu/primer/java/prism/index.html http://www.techxhome.com/lightsite/optics/refraction/monoPrism.html refraction & refl. http://www.techxhome.com/lightsite/optics/dispersion/whitePrism.html dispersion

30. Rainbow

31. Rainbow *Rainbow http://www.phy.ntnu.edu.tw/java/Rainbow/rainbow.html http://www.techxhome.com/lightsite/optics/dispersion/raindrop.html rain drop

34. Ice Crystals

35. Sun Dogs

40. Halos

42. 22 degree halo

43. 22 degree halo

44. 46 degree halos

45. Chapter 3 Reflection in Curved Mirrors

46. Mirrors *Concave Mirrors http://www.techxhome.com/lightsite/optics/mirrors/sphereMirror.html *Concave Lens: virtual image *Convex Mirrors http://www.techxhome.com/lightsite/optics/mirrors/mirrorAberr.html spherical aberration