Lens Technologies

MicroscopesInvented 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 InnovationReduced

chromatic aberration

Modern Telescopehttp://

www.youtube.com/watch?v=0jPE7u3bz_E

BinocularsTwo refracting

telescopesTotal internal

reflectionLonger light path

results in better magnification

Sight & Human Eye

Structure – Human Eye

Cow Eye Dissection - http://www.youtube.com/watch?v=hZ4mUMsMfTQ&feature=related

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 LensesCommon causes of poor vision:Incorrect shape of eyeballIncorrect shape of corneaHardening of the lens

Corrected by:GlassesContact lensesLaser 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

PresbyopiaSymptoms 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.

AstigmatismCornea is

oval shaped instead of spherical.

Causes light to focus on two or more spots.

Night Vision DevicesYou tube rescue with Night Vision

Aid (40 sec. long)http://www.youtube.com/watch?v=u-6Vd1gc8AAYou tube night vision goggles (3

minutes long) http://www.youtube.com/watch?v=BOpJzH0XX-c

Optical Illusions

Optical Illusions

Optical Illusions

Optical Illusions

Optical Illusions

Optical Illusions

Animated Optical Illusionshttp://

www.youtube.com/watch?v=lvvcRdwNhGM

http://www.youtube.com/watch?v=T5xtRdLOopU

I “Speye” Activity & Homeworkp. 514 - Complete Part 1 – 3 with a

partnerp. 511 # 4, 5 and 8