Optics for VO 1

Question 1

Thin lens Approximation

Answer 1

No significant change in vergence as you move bet first and second surface
Light doesnt converge/diverge significantly bet the surfaces

Question 2

Focal Points

Answer 2

Tells us where light travelling parallel from an infinitely distant object is actually focused
F’ = Back focal point - back of lens - A point object at infinity forms an image here
F= An object placed at F forms an image at infinity

Question 3

Vergence

Answer 3

L=n/l
n is refractive index and l is distance from image
converging = + vergence
diverging = - vergence

Question 4

Power of Thin Lens, F

Answer 4

F = -n/f = (- refractive index in object space/ front focal length)
=n’/f’ (refractive index in image space/ second focal length)

Question 5

Paraxial Surface Power

Answer 5

• surface power depends on radius of curvature and difference in refractive index
  F=(n’-n)/r

Question 6

The Refraction Equation

Answer 6

L’=L+F

Question 7

Optics of the Human Eye

Answer 7

• There is no clear optical axis
• When you look/ fixate on an object, the light falls on your fovea centralis to use your best acuity - visula axis
• Angle a is the angle bet the visual and optical axis. It is 5 degrees nasal and 2 degrees upward on average
• Can approximate cornea by one surface
• Lens is approximated to have homogeneous n

Question 8

Visual Axis

Answer 8

Principal ray that passes from the edge of the object through the centre of the entrance pupil and is incident on the centre of the fovea