Optics

We began class by reviewing applications of optics:
Stereoscopic Vision
    We are able to perceive our depth perception by the use of binocular vision. An object must be imaged by two cameras to view a 3D image as each of our eyes receives a different image, This can be done by the use of anaglyphs, color filter glasses and a head mount display. 
Microscope
     Microscopes use converging lenses to magnify objects too small for the eye to see. To obtain larger images two or more lenses are combined to make a simple compound microscope. 
Projector
     Two converging lenses in a projector refract light so that an object is uniformly illuminated. The object is placed a distance of one of two focal lengths in front of the projection lens, resulting in a large real image. 
Camera
     Light enters a camera lens system and strikes a plane mirror. Light is reflected up to the pentaprism where total internal reflection guides the light through the viewfinder. When the photograph is snapped the mirror lifts up and allows light to strike the film. 

     We then wrote our quizzes on ray diagrams and thin lens equations as well as discuss various eye prescriptions. If you have 20/20 vision, it means that when you stand 20 feet away from an object you see what the 'normal' person sees at 20 feet. Examples of prescriptions are -3.5, 7.1. 

      Notes:

Opticians prefer to use the optical power P of a lens instead of a focal length. Power is measured in diopters (D).

P= 1/f

f must be in meters to have P to be in Diopters. 

The optical power is positive for converging lens and negative for diverging lenses. The higher the optical power the shorter the focal length. 

Example

1. A nearsighted person can focus on objects no father than 20.0 cm from the eye. What power of a lens is needed to enable the eye to focus the eye on distant objects clearly?

First identify whether they need a converging or diverging lens. 

Diverging. Object is distant. 

do= infinity

f= ?

di= -20.0com

1/di+ 1/do = 1/f

1/-20 + 1/infinity =i/f 

= 0

The next person to go must be the quickest at saying the alphabet backwards. :)