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Unformatted text preview: Ch 32 Reflection and Refraction L23 Focus: “Ray” Optics approximation—neglecting diffraction “Image” is located where rays appear to come from Refracting surfaces HeNe Laser b θ Find θ ( b ) as precisely as possible. For a given Δ b b Δ = Δ λ θ θ λ θ λ >> Δ ≈ Δ >> b b min θ λ θ ≈ >>> b Scale of b = lens diameter Δ b aperture want θ >> Δθ and b >> Δ b For “Ray” optics, Condition for “Ray” Optics If all angles are large compared to the diffraction angle, the ray optics approximation is valid. Ch 32 Reflection and Refraction L23 Images formed by Flat Mirrors P Object h Image is as far behind mirror as object is in front. No leftright reversal, only frontback reversal. Lateral Magnification: 1 ' height object height image = = = h h M Upright image M > 0. Virtual Image: No light is actually coming from here! h ’ But, rays appear to come from here. Ch 32 Reflection and Refraction L23 Total Internal Reflection : Fiber Optics n 1 n 2 θ 1 Snell’s Law: n 1 sin θ 1 = n 2 sin θ 2 For n 1 > n 2 there will be a critical θ 1 = θ c where θ 2 = 90 o and sin θ 2 is maximum = 1....
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 Spring '09
 Thomas
 Physics, Diffraction, Reflection And Refraction, angular magnification, optical instruments, Optical Instruments L24

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