Lens Technologies
Microscopes Invented by Johannes and Zacharias Jansen in 1590 Larger inverted image Used in study of cells and diseases
Refracting Telescopes: Galileo and Kepler
Reflecting Telescope: Newton’s Innovation Reduced chromatic aberration
Modern Telescope _E _E
Binoculars Two refracting telescopes Total internal reflection Longer light path results in better magnification
Sight & Human Eye
Structure – Human Eye Cow Eye Dissection -
Focussing – Human Eye Ciliary muscles make the lens shorter and thicker to focus a nearby object Relaxed eye lens focusses on a distant object
Eye vs. Camera
Correcting Vision Using Lenses Common causes of poor vision: Incorrect shape of eyeball Incorrect shape of cornea Hardening of the lens Corrected by: Glasses Contact lenses Laser eye surgery
Myopia – Near Sightedness Long eyeball results in image formation in front of the retina Rays spread again and result in blurry image
Hyperopia – Far Sightedness Short eyeball results in reaching of light rays at the retina before they converge Blurry image
Presbyopia Symptoms often like Hyperopia (far sightedness) Aging causes ciliary muscles to be less flexbile and can no longer make the lens change shape to focus on objects at different locations Solution is bifocals.
Astigmatism Cornea is oval shaped instead of spherical. Causes light to focus on two or more spots.
Night Vision Devices You tube rescue with Night Vision Aid (40 sec. long) 6Vd1gc8AA You tube night vision goggles (3 minutes long) XX-c XX-c
Optical Illusions
Animated Optical Illusions wNhGM wNhGM dLOopU dLOopU
I “Speye” Activity & Homework p Complete Part 1 – 3 with a partner p. 511 # 4, 5 and 8