A reader's pupil has contracted to a diameter of under office lighting

PHYSICS · Multi-part · Fermi University Physics · Optics & Photonics · Biophysics & Medical Physics · Geometrical optics and imaging

Forces, Machines and Signals, Ch Vision and photoreception: counting photons

Problem

A reader's pupil has contracted to a diameter of

d_p = 3.5\,\mathrm{mm}

under office lighting. Take the wavelength of peak daylight sensitivity as

\lambda = 555\,\mathrm{nm}

, and use the eye's nodal distance of

16.7\,\mathrm{mm}

and a foveal cone spacing of

2.5\,\mathrm{\mu m}

(angular spacing

0.51'

) as before. ((a)) Compute the Rayleigh diffraction limit of the eye at this pupil diameter, in minutes of arc. ((b)) Compare the Rayleigh angle with the finest grating period the cone mosaic can represent, and state which of the two, the optics or the mosaic, sets the coarser and therefore limiting scale at this pupil size.

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