1. Image formation in eyes and cameras
Section 4.1
Image formation in eyes and cameras

2. Human Eye
In the eye, the device (or part of the eye) that controls the amount of light entering is called the iris (the colored part of the eye), which changes the size of the pupil

3. Sight
Physically, sight requires that light is cast upon the pupil of one or both of the eyes, pass through the lens, through the aqueous and vitreous humors, onto the retina. From the photoreceptors there -- millions of light sensitive nerve endings called rods and cones -- nerve impulses must then be transmitted through the optic nerve to the brain. In the brain, these nerve messages are analyzed for their arrangement / pattern, and its meaning.

4. Human Eye Cornea: Aqueous humor: Transparent cover for the eye
jelly-like fluid found between the cornea and iris
Note: Some refraction occurs as light passes through the different materials

5. Human Eye Pupil: Iris: opening that allows light to enter into the eye
colored ring around the pupil
Controls how much light enters the eye by changing the size of the pupil

6. Human Eye Lens Ciliary Muscles focuses light
Pull on the lens to change the shape, adjusting the refraction of light onto the retina (help with focusing on distances)

8. Human Eye Vitreous humor:
jelly-like fluid that provides the eye with it’s shape between the lens and retina

9. Human Eye The retina The back of the eye that detects light and color
Fovea Centralis or Macula: vision center (highest concentration of cones)
Rods: light sensing cells
Cones: color sensing cells

10. Human Eye
Transmits visual information from the rods and cones to the brain for interpretation
*Blindspot

11. Human Eye in Comparison
A Camera

12. Iris and Pupil operate in much the same way as the diaphragm controls the aperture (opening) of the camera lens.

13. The film at the back of the camera contains light sensitive chemicals, which change when light hits it. These chemicals form the image on the film.

14. In a camera, if an object moves closer to the film, the lens must move away to keep the image in focus. In the human eye, the lens cannot move, so the ciliary muscles change the shape of the lens (by making the lens bulge in the middle if the image comes closer to you and stretch if the object is further away).

15. Lasik Eye surgery
Changes the shape of the cornea

16. Laser
Instead of wearing glasses many people are now opting to have an eye surgeon use a laser to correct a vision problem. 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.
In 1966, Theodore H. Maiman, a physicist at Hughes Aircraft Company in California became the first person to use a process called ...
light amplification by the stimulated emission of radiation or laser light.

18. Technologies Night Vision Goggles
In night vision goggles, 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. Infrared Technologies