# Chapter 12-2012

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Category: Education

The Eye

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The EYE Chapter 12 References: Eye and Brain by R. L. Gregory; Visual perception : a Clinical Orientation by Steven H. Schwartz c Leon Gunther

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1. compound lens 2. iris 3. variable focal length 4 . photo-sensors on surface 1. compound lens 2. iris 3. variable image distance 4. photo-sensors on surface George Wald, 1959 courtesy Scientific American

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Accommodation 1 Applet http:// mysite.verizon.net /vzeoacw1/ eye_applet.html To view applet, click on box in slide show

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Accommodation 2 Applet For each, vary f and object distance (if not far source) to focus on retina: Healthy eye Farsighted eye Nearsighted eye See what happens when you move source off axis! http:// ephysics.physics.ucla.edu /optics/html/ eye.htm To view applet, click on box in slide show

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Problem : An eye has a retina that is 24.0mm from the eye lens. It focuses an object that is 2.00m away and has a height of 40cm. Find the focal length of the eye lens and the height of the image on the retina. NOTE re MAGNIFICATION: We don ’ t need to know the focal length in order to determine the magnification . It is determined by the object distance and the image distance. THUS

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Problem : An eye has a retina that is 24.0mm from the eye lens. It focuses an object that is 1 0.0m away and has a height of 40cm. Find the focal length of the eye lens and the height of the image on the retina. object distance vs. focal length d 0 f __________ ____________ 50 cm 2.29 cm 2.0 m 2.37 cm 10 m 2.39 cm ?

### PowerPoint Presentation:

Problem : An eye has a retina that is 24.0mm from the eye lens. It focuses an object that is 1 0.0m away and has a height of 40cm. Find the focal length of the eye lens and the height of the image on the retina. object distance vs. focal length d 0 f _____________________ _________________________ 50 cm 2.29 cm 2.0 m 2.37 cm 10 m 2.39 cm 2.40 cm

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d ie Accommodation f object distance d o lens – retina distance

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d ie Accommodation f object distance lens – retina distance max f > d ie min f near point HEALTHY ACCOMMODATION T o see an object at infinity, need f= d ie

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d ie Accommodation f object distance lens – retina distance HYPEROPIA cannot see objects at infinity max f

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d ie Accommodation f object distance lens – retina distance max f min f near point too great cannot see close up MYOPIA

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fovea optic nerve RETINA

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Source : http :// users.rcn.com / jkimball.ma.ultranet / BiologyPages /V/ Vision.html , courtesy of David Copenhagen; produced by David Copenhagen, Scott Mittman , and Maria Maglio

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Distribution of Cones and Rods

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Rods & Cones – Nerve Fibers See RL Gregory, “Eye and Brain”

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FATIGUE reveals Complementary Colors Effect of Fatigue: Complementary colors are produced. [see Ch. 14 for details]

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FATIGUE reveals Complementary Colors Effect of Fatigue: Complementary colors are produced. [see Ch. 14 for details]

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FATIGUE + Complement

DEPTH Perception