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The Eye

The Eye. The eye is an optical lens system. Two single lenses. The goal of the eye is to focus an image on the retina. Eye Dissected. The cornea is a curved membrane with fluid behind it. Two indices of refraction n corn = 1.376 n aq = 1.336

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The Eye

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  1. The Eye

  2. The eye is an optical lens system. Two single lenses The goal of the eye is to focus an image on the retina. Eye Dissected

  3. The cornea is a curved membrane with fluid behind it. Two indices of refraction ncorn = 1.376 naq = 1.336 This is roughly the refraction from air to water. Eye works poorly underwater Corneal Lens

  4. The lens is a denser material for fine focusing. nlens = 1.406 at maximum Relaxed muscle provides little additional focus. For distant objects Contracted muscles provide more focus. Relaxes tension and creates a bulge For near objects Crystalline Lens

  5. The moon subtends an angle of about 0.009 rad as seen from the earth. The size of the moon on the retina comes from the image triangle. The focusing by the lens is called accommodation. The relaxed lens forms a combination with the cornea. Object focus 15.6 mm in front of cornea Image focus 24.3 behind Optical center 17.1 mm in front of the retina Typical shifts in accommodation are a few mm. Accommodation

  6. The retina is the screen for the eye. Light sensitive cells Neurons for signal transmission Ideally it should be at the focal plane. Otherwise image is blurred Retina

  7. A pinhole opening can act as a single lens. Forces ray convergence at the opening point Iris in eye can act as pinhole lens A pinhole camera is a box with a pinhole opening to focus light. Pinhole Camera

  8. A single lens reflex (SLR) camera acts much like an eye. Shutter like iris Lens fixed Adjust distance to screen Single Lens Reflex next

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