lecture01A

# lecture01A - Geometric Optics and Images Lecture 2...

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1 Geometric Optics and Images Geometric Optics and Images Lecture 2: Geometric Optics and Images Reading: Ch. 34 2-9 Main Idea: Optics is a subbranch of physics that has survived the test of time. We will demonstrate that a very crude approximation to the full theory of EM radiation suffices to capture many of the most common optical phenomena.

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2 Last Time Last Time Light is a traveling electromagnetic oscillation predicted by Maxwell's equations. Our eyes detect only a small range of wavelengths of EM waves, which we call the visible spectrum. Light displays properties characteristic of waves (interference) and particles (discretized energy packets). Light carries energy and has momentum. Light travels at the same speed c=3.0e8 m/s in every inertial frame. Light can be linearly polarized → all transverse oscillations are aligned. Light slows down in transparent matter. Different wavelengths slow to slightly different speeds → leads to refraction.
3 What is an image? What is an image? Visual information is collected by the cells in the retina → location in the visual field, colors, intensity Visual cortex processes the information and produces an image in your mind. Your brain processes refracted and reflected visual information by the exact same process → produces images of objects that are not as they are in the physical universe.

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4 Types of images Types of images We characterize images in two ways. Real: can be formed on a screen, does not depend on your seeing it. → Think: movie projector Virtual: object only exists in the location you perceive it because the rays from the object are diverted. → Think: flat mirror
5 How a plane mirror produces a virtual image (VI) How a plane mirror produces a virtual image (VI) A plane mirror is an object sufficiently smooth that reflects a ray without scattering or absorbing. Perceived (virtual) image appears behind the mirror due to the path of the reflected rays. Convention: Virtual image (location i is taken as negative ) p i p =− i

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Location of image is independent of observer Location of image is independent of observer For any mirror and a given observer, there is one ray that travels from the object to the observer. To any observer, the image is in the same location w.r.t the object → why we write relationships between p & i without reference to location of the observer. p
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## This document was uploaded on 10/27/2011 for the course PHYS 214 at Penn State.

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lecture01A - Geometric Optics and Images Lecture 2...

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