32 Optical Images

1
32 Optical Images

• image formation
• reflection refraction
• mirror lens equations
• Human eye
• Spherical aberration
• Chromatic aberration

2
image formation

• real image rays converge to a pointEx. suns
  rays focused by magnifier
• virtual image apparent source of light
  divergence Ex. image seen in mirror

3
Plane Mirror Image

• distances measured from mirror axis
• image height hi object height ho
• object distance do image distance di

4
concave mirror images
4
5
convex mirror images

• always virtual, upright, diminished

5
6
lens images
6
7
Lens Mirror Equation

• relate do, di f.
• lateral magnification (LM) hi/ho.

you must learn the sign conventions to use these
formulas
7
8
imbedded object

• image distance lt object distance

9
lens power

• power 1/(focal-length(meters))
• unit D, diopters, 1/m
• used for corrective lenses
• Ex. near-sighted person P -5.0Df 1/P
  1/(-5) -0.2m -20cm.

9
10
human eye

• average index of refraction 1.4

11
Far Sighted Eye

• correction requires converging lens

12
near sighted eye

• correction requires diverging lens

13
Spherical Aberration

• Spherical aberration light striking near edge
  focus at different points than light striking
  near center

14
ChromaticAberration

• Chromatic aberration different colors focus at
  different points

15
Summary

• Image formation by lenses mirrors
• Real/virtual, orientation, magnification.
• Near far-sighted problem correction
• Spherical chromatic aberration

16
2. A document is sealed in a glass cube (n1.5)
at a depth of 10cm from one surface. Calculate s
and m.
Object is in n11.5. Viewer is in air n21.00.
Radius of surface is r infinity.
? 1/s -0.15 ? s -6.67cm.
.
17
O
I
18
Question Reverse the designations in the example
above. Object is now the fish, so n1 1.33 (fish
location). Let the fish be 10cm from bowl
surface. Where is the image of the fish formed
that the cat will see?
Answer s 10cm , s ?, r -15cm, n1 1.33,
n2 1.00.
? 0.133 1/s 0.022 ? 1/s -0.111 ? s
-9.00cm
19
Calculating Focal Length for a Thin Lens
Example A double convex, thin glass lens with n
1.5 has radii of curvature of 10 and 15cm. Find
its focal length.
20
(No Transcript)
21
(No Transcript)
22
s, cats nose
n1 holds object, here equal to 1.00
0.1 1.33/s 0.022
1.33/s -0.078
s -17.1cm
23
(No Transcript)
24
(No Transcript)
25
(No Transcript)