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Optics Class Announcements and Study Guide

Updates on prayer, term project progress reports, and specific assignments for students Joshua, Thomas, Mike, Rachael, and Ken. Quick writing tasks and reading quizzes on optics concepts such as lenses, aberrations, f-number, and cameras. Information on correcting nearsighted and farsighted vision with lenses.

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Optics Class Announcements and Study Guide

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  1. Announcements 11/7/11 • Prayer • Term project progress reports due Saturday night • Slinkies! (Joshua M, Thomas, Mike, Rachael, and Ken—this means you!) Frank & Ernest

  2. Class-designed problem • p = _____ • Lens 1: f = _____ • Distance to Lens 2 = _____ • Lens 2: f = _____ • q2 = ? Real or virtual? • Mtot = ? Upright or inverted? • Ray diagram? (for first lens, anyway)

  3. Quick writing • Draw the ray diagram for this situation: Converging lens, f = 20 cm, p = 80 cm

  4. Quick writing • Draw the ray diagram for this other situation: Converging lens, f = 20 cm, p = 15 cm

  5. Quick writing • Draw the ray diagram for this third situation: Diverging lens, f = -20 cm, p = 15 cm

  6. Reading Quiz • What’s the term used to refer to rays failing to focus because a lens is shaped incorrectly? • elliptical aberration • hyperbolic aberration • parabolic aberration • spherical aberration

  7. Spherical Aberration Credit: the next several slides were produced by Dr. Durfee

  8. Reducing Spherical Aberration with Aperture

  9. Spherical Aberration

  10. Reducing Spherical Aberration by Reversing Lens

  11. Coma

  12. 0 Degree Tilt

  13. 10 Degree Tilt

  14. 20 Degree Tilt

  15. 30 Degree Tilt

  16. 40 Degree Tilt

  17. 40 Degree Tilt + Aperture

  18. Lens-makers’ eqn: Thought question • Red light coming from O produces an image at I. Where will blue light coming from O form an image? • same place • closer to the lens • farther from lens ChromaticAberration

  19. How does a camera work? • Simplest picture • What if you leave out the lens? • What’s a pinhole camera?

  20. Reading Quiz • What is the f-number of a lens? • The focal length in meters • The focal length in inches • One over the focal length in meters • The focal length divided by the diameter of the lens • The focal length divided by 25 cm

  21. q Thought question • How does the f-number of a lens relate to the half-angle of the “light cone” formed by parallel light entering the lens?

  22. Cameras: f-stops • Which has the higher f-number? • What’s the advantage of one over the other?

  23. Thought question • If you have trouble seeing things far away but can see close objects well, you are “near-sighted”. What kind of lenses do you need in your glasses? • Converging lenses • Diverging lenses

  24. Near point vs. Far point • Far point: how far away can you focus on things • Regular person: fp = infinity • Nearsighted person: fp = much smaller • For me, my fp  1 m (right eye), 0.5 m (left eye) • Near point: how close can you see things comfortably • Regular person: np  25 cm • Farsighted person: np = much larger How to fix things with glasses? Nearsighted: object at  cm  image at –fp (diverging lens) Farsighted: object at 25 cm  image at –np (converging lens)

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