Question

The optical power of the human eye is 60D. Find the effective focal length and the angular resolution of the eye for a 2 mm pupil at the wavelength of light λ = 0.55 µm

Answer 1

Optical power human eye P= 60 D

The optical power of the human eye is sum of the powers of cornea and eye lenses. Therefore the effective focal length is reciprocal of this power of the eye . Or the effective focal length is the sum of focal length of cornea and eye lens

Effective focal length f = 1/ P

f = 1/(60)

f = 0.01666m

f = 1.6cm

​​​wavelength = 0.55 × 10 -6 m

Diameter D = 2mm = 2× 10 -3 m

Angular resolution = ( 1.22 )/ D

= ( 1.22 × 0.55× 10 -6) / (2× 10 -3 ) rad

= 3.355 × 10 -4 rad

= 3.55 × 10 -4 × (180/ ) × 60 minute

= 1.153 minute

Angular resolution = 1.153 m