Intereference of light (at least i think it is) and the human eyeball

[kehler]

Homework Statement

A human eyeball has roughly a diameter of 15mm. The diameter of the pupil can be up to roughly 5mm. Do you think that the fact that the light receptors on the retina are spaced by at least 2 micrometers is just a coincidence? Justify your answer.

The Attempt at a Solution

I don't know exactly what the question wants.
I considered the pupil to be a slit, used d sin theta = n lambda for lambda = 400nm (wavelength of violet), and then found that the distance between maxima for violet is 1.2 micrometers. For lambda = 700nm (red light), the distance between maxima is 2.1 micrometres.
I expected both values to be either greater than or less than 2 micrometers. (Then I could make up some crappy explanation about having the distances between maxima for all the colours to be greater/less than 2 micrometers )
But obviously that didn't work for me so I guess that's not the right way to do it. Any ideas how to do this?

 

[alphysicist]

Hi kehler,

I believe this problem is referring to the resolving power of a circular aperture. Your textbook probably has a section or part of a section talking about it.