Science8 Unit C Lightand Optics Section4 Lesson7 Image Formationin Eyesand Cameras


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Camera Eyes
Human Eye Anatomy
Blind Spot
near sightedness
Animal eyes
Compound eyes

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Science8 Unit C Lightand Optics Section4 Lesson7 Image Formationin Eyesand Cameras

  1. 1. Section 4 Pages 230-238 Science InAction8 Lesson 7 Image Formation in Humans, Animals and Cameras
  2. 2. I can explain how objects are seen by the eye,  and compare eyes with cameras. I can investigate and describe the development  of new technologies to enhance human vision. I can compare the function and design of the  mammalian eye with that of other vertebrates and invertebrates.
  3. 3. IRIS  colored part of the eye controls the  amount of light entering, which changes the size of the pupil Known as the  diaphragm in a camera
  4. 4. The natural adjustment in  the size of the pupils is called the iris reflex, which is extremely rapid. This iris reflex action the  pupil when you automatically adjusts go from a darkened area to a well-lit area, or, from a well- lit area to a darkened one.
  5. 5. Pupil  Hole that light enters In a camera,  the hole is known as the aperture
  6. 6. Retina  Photoreceptor cells in the retina detect light (rods are highly sensitive to light and cones detect color) They produce  small electrical impulses from the retina to the brain, by way of the optic nerve.
  7. 7. The film at the back of The parts of a camera   the camera contains are housed in a rigid light sensitive lightproof box, chemicals, which whereas layers of change when light hits tissue hold the it. Like the retina. different parts of the eye together. These chemicals form  the image on the film.
  8. 8. Ciliary Muscles Contract to  lengthen the lens and relax to shorten the lens
  9. 9. In a camera, if an object  As people become  moves closer to the film, older, the lens stiffens the lens must move away and loses its' ability to to keep the image in focus. change shape (doesn't bulge) In the human eye, the  lens cannot move, so the ciliary muscles change the Many people need to  shape of the lens. wear (convex lens) The process of changing reading glasses, so that  the shape of the lens is the images can be called accommodation. focused.
  10. 10. Vitreous Humour The eyeball  contains fluids, called humours, which prevent the eyeball from collapsing and refract the light that enters the eye.
  11. 11. The lens in the human  eye is a convex lens, which focuses the light rays entering your eye to a point on your retina . Some people however  have eyes that are too long or too short.
  12. 12. If the eye is too  long, the image forms in front of the retina trouble seeing  distant objects
  13. 13. If the eye is too  short, the image forms behind the retina Objects that are  close to them are difficult to see
  14. 14. The shortest distance On average, an adult   at which an object is has a near point of in focus is called the about 25 cm, whereas near point of the eye. babies have a near point of only 7 cm. The longest distance  is called the far point The far point is  of the eye. infinite.
  15. 15. In 1966, Theodore H.  Maiman, a physicist at Hughes Aircraft Company in California became the first person to use the L.A.S.E.R. Light Amplification by  the Stimulated Emission of Radiation
  16. 16. Laser light is quite Lasers have many useful  different. applications:  Scanners (bar codes in It gives off a single retail shops are scanned  wavelength (frequency) to give the price) of coherent light.  Digitized data are read by a laser on a compact disk (CD)  Lasers are use by law enforcement officers to detect the speed of vehicles.
  17. 17. Laser light can be In either form, it is so   released in pulses or in powerful, that it can a continuous beam. make precise cuts through metal  Can also be used in surgery, as a scalpel - or, to instantly seal broken blood vessels, because it produces such intense heat.
  18. 18. The surgeon cuts a thin flap of tissue covering the eye,  fold it over, then the cornea is reshaped with a laser. The reshaped cornea acts like a corrective lens,  allowing the light to be bent so it will properly focus on the retina.
  19. 19. Light is focused onto an  image intensifier. Inside the intensifier, the  light energy releases a stream of particles, which hit a phosphor- coated screen. These glow green and  the person looking in the goggles can view a green image.
  20. 20. The point where the View this image at arm's   retina is attached to the length. optic nerve does not Cover your right eye with  have any light sensitive your hand. cells. This point is known Stare at x, slowly leaning  as the blind spot. closer to the image, until the dot disappears (when Page 233 for the activity you reach your blind  spot) and then reappears when you have passed your blind spot.
  21. 21. ... explain how objects are seen by the eye, and compare eyes with cameras? ... investigate and describe the development of new technologies to enhance human vision?
  22. 22.  Page 235, 1-5 #1. Make a chart that lists the parts of the eye and the parts of the camera, and their function. What do the camera and the eye have in common? How are they different?
  23. 23. Page 235, 1, 3-5  #3. What does the laser surgery method of vision correction have in common with wearing glasses to correct vision? ______________________________________ ______________________________________ ______________________________________ ______________________________________ ______________________________________
  24. 24. Page 235, 1, 3-5  #4. If you wish to take a picture of faint stars in the night sky, how should you adjust your camera? ______________________________________ ______________________________________ ______________________________________ ______________________________________ ______________________________________
  25. 25. Page 235, 1, 3-5  #5. Describe how night vision goggles enhance human vision. ______________________________________ ______________________________________ ______________________________________ ______________________________________ ______________________________________
  26. 26. Eyes that have a  cornea, a lens and a retina are called camera eyes. Vertebrates (animals  with backbones) for the most part have camera eyes.
  27. 27. Fish have camera  eyes with a perfectly round lens. It bulges out from the  pupil, allowing it to see in practically every direction.
  28. 28. Birds have sharper  vision than humans because they have five types of cones (humans have only 3). All are sensitive to  different wavelengths of light.
  29. 29. Nocturnal animals They also have many   have eyes that collect more rods than cones as much light as in their retina making possible because of their eyes more their very large pupils. sensitive to low levels of light. They also have a layer,  called tapetum lucidum, inside their eye, which acts as a mirror.
  30. 30. Insects and An ommatidium looks   crustaceans have like a long tube with a compound eyes. lens on the outer surface, a focusing cone below it, Each eye is made up of and then a light sensitive  many smaller units cell below that. called ommatidium.
  31. 31. The compound eye is  great for spotting movement, but with so many lenses it is difficult to form a single coherent image. Instead it forms a  mosaic image (much like a tv screen).
  32. 32. ... compare the function and design of the mammalian eye with that of other vertebrates and invertebrates?
  33. 33. Page 238, #1-3  #1. How is a human eye similar to and different from a bird’s eye? ______________________________________ ______________________________________ ______________________________________ ______________________________________ ______________________________________ ______________________________________
  34. 34. Page 238, #1-3  #2. How is a compound eye different from a human eye? ______________________________________ ______________________________________ ______________________________________ ______________________________________ ______________________________________ ______________________________________
  35. 35. Page 238, #1-3  #3. How does an ommatidium help an insect survive and thrive in its environment? ______________________________________ ______________________________________ ______________________________________ ______________________________________ ______________________________________ ______________________________________