1. LENSES

2. CONVERGING LENS
Convex shape- will cause the rays to converge to a single point called the focus. Produce both virtual and real images.

3. DIVERGING LENS
Concave shape- will cause rays to diverge outwards. Produce virtual images only.

4. DRAWING RAY DIAGRAMS
Light rays moving parallel to the principle axis are refracted through the focus.
Rays passing through the focus on one side of the lens will be refracted parallel to the principle axis.
Rays passing through the optical center of the lens continues without refracting.
Use two of these to locate an image.

5. RAY DIAGRAMS
Principle
axis

6. CASE 1 Object beyond 2f IMAGE: Inverted Smaller Between f & 2f Real

7. CASE 2 Object is at 2f IMAGE Real Inverted At 2f Same size as object

8. CASE 3 Object is between f and 2f IMAGE Real Inverted Beyond 2f Larger

9. CASE 4 Object is at the focus: NO IMAGE IS FORMED, RAYS ARE PARALLEL

10. CASE 5 Object is between the lens and the focus IMAGE: Virtual Upright
Larger
Same side of lens as object
image
f object f

11. DIVERGING LENS DIAGRAM
Image: Always virtual, upright, smaller and same side as object

12. Chromatic Aberation
The lens will refract different colors of the spectrum to different focal points.
Can be corrected with an oppositely refractive lens.

13. SPHERICAL ABERATION
Defect due to the thickness of the edge of the lens. Rays refract to different foci.
Image will be out of focus.
Can be corrected with an aperture that limits light passing though the edge of the lens.