thick lenses

Question 1

What kind of lens is real?

Answer 1

thick lens

we cannot ignore the lens thickness and its effect on optical power

Question 2

thickness of a lens

Answer 2

• separation between the two lens vertex points
• always positive
• m

Question 3

the optical power of a thin lens is…

Answer 3

the sum of the optical powers of each SSRI

Question 4

OP of thick lens

Answer 4

P=P1+P2-(d/n)P1P2
d is always positive
n is always positive

Question 5

the OP of a thick lens, in comparison to the sum of the OPs of the two SSRIs is…

Answer 5

can be smaller or larger

Question 6

Are all thick convex lenses plus?

Answer 6

no, a very thick convex lens can be minus

Question 7

OP of a real, thick lens

Answer 7

depends on

• the radii of curvature R of the refracting surface
• the lens material RI in relation to the surrounding medium RI
• surface separation (lens thickness) d.

Question 8

Ball lens

Answer 8

a biconvex lens with thickness equal to twice the radius of curvature R of its surfaces

d=2R

Question 9

For ball lens of glass with n=1.5, the focal distance in air is…

Answer 9

f=1.5xR

Question 10

Hoegh Meniscus

Answer 10

• flat piece of glass bent

- refracting surfaces with the same radii curvature (R1=R2=R), but with slightly displaced centers of curvature

Question 11

The Hoegh Meniscus…

Answer 11

has positive optical power

P=(d/nv)([nv-1]^2)/R^2

Question 12

Size lens

Answer 12

same centers of curvature but different radii of curvature (R1>R2)

plus OR minus

Question 13

cornea

Answer 13

• meniscus
• center is 540microns
• positive lens