1 / 12

Geometrical Optics and Lenses

Geometrical Optics and Lenses. Snell’s Law Examples of Snell’s Law Total Internal Reflection Fiber Optics www.cmog.org (Corning NY) Ray Tracing and Thin Lenses Example – real image Example – inverted image Sign Rule and Summary. Index of Refraction.

faraji
Télécharger la présentation

Geometrical Optics and Lenses

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Geometrical Optics and Lenses • Snell’s Law • Examples of Snell’s Law • Total Internal Reflection • Fiber Optics www.cmog.org (Corning NY) • Ray Tracing and Thin Lenses • Example – real image • Example – inverted image • Sign Rule and Summary

  2. Index of Refraction • Ratio of speed in vacuum to speed in medium • Important when passing from one medium to another • Light’s speed in diamond (n=2.42) • Index of refraction of various materials <table 23-1>

  3. Snell’s Law - Refraction • Governs how light ray goes from one medium to another • Snell’s Law • Toward normal in faster medium • Person in swimming pool • Also Reflection Law

  4. Refraction through flat glass Light travelling in air strikes a flat piece of uniformly thick glass at an incident angle of 60°.If the index of refraction is 1.5, what is the angle of refection θa in the glass, and the angle θb at which the rays emerges from the glass? • For the angle in the glass θa • For the angle in the glass θa • Emerges at the same angle it went in

  5. Apparent depth of pool A swimmer has dropped her goggles to the bottom of the pool at the shallow end, marked as 1.0 m deep. But the goggles don’t look that deep. Why? How deep to the goggles appear to be? • Snell’s Law • But θair is angle light appears to be coming from! • Since sinθ≈θ≈tanθ for small angles, so

  6. Critical Angle • Going from high to low index θ increases • Sinθ2 = 1 determines maximum angle θ1 that can be transmitted! • Critical angle for water • Fiber optics makes use of Critical angle

  7. Light Bending at thin lens • Thin lens • Principal axis • Focal point • Air-glass interface • Entering glass bent toward normal (down) • Leaving glass bent away from normal (also down)

  8. Real image at thin lens

  9. Example – Converging Lens What is • the position, and di = 5.26 cm • the size, m = -.0526 hi = -.40 cm of a 7.6 cm high flower placed 1.0 m from a 50 mm focal length camera lens? Image real and inverted

  10. Example - Close to converging lens An object is place 10 cm from a 15 cm focal length converging lens. Determine the image • position and di = -30cm • size. m = 3 Image virtual and upright

  11. Sign convention

  12. Diverging Lens Where must a small insect be placed if a 25 cm focal length diverging lens is to form a virtual image 20 cm in front of the lens? do = 100 cm

More Related