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he limit to the eye\\\'s acuity is actually related to diffraction by the pupil.

ID: 1512520 • Letter: H

Question

he limit to the eye's acuity is actually related to diffraction by the pupil. What is the angle between two just-resolvable points of light for a 3.75 mm diameter pupil, assuming the average wavelength of 569 nm? Take your result to be the practical limit for the eye. What is the greatest possible distance a car can be from you if you can resolve its two headlights, given they are 1.30 m apart? What is the distance between two just-resolvable points held at an arm's length (0.800 m) from your eye?

Explanation / Answer

1) rayleigh criterion

sin theta = 1.22 lambda/D

theta = arcsin(1.22*569E-9/3.75E-3)

         = 0.01061 degrees

2) tan theta = y/L

L = 1.3/tan(0.01061 degrees)

   = 7023 m

3) y = L tan theta

       = 0.8*tan(0.01061 degrees)

        = 1.5 E-4 m