Three separate set-ups.

PHYSICS · Multi-part · Fermi University Physics · Optics & Photonics · Interference and diffraction · Interference and diffraction

Optics and Photonics, Ch Fraunhofer diffraction from apertures and gratings

Problem

Three separate set-ups. ((a)) A slit of width

b = 0.30\ \mathrm{mm}

is illuminated by red light of wavelength

700\ \mathrm{nm}

, and the pattern is viewed on a screen

L = 3.0\ \mathrm{m}

away. Compute

b^2/\lambda

and decide whether the screen is in the far field. ((b)) A telescope objective has diameter

D = 60\ \mathrm{mm}

. Find its smallest resolvable angular separation at

\lambda = 650\ \mathrm{nm}

, in arcseconds. ((c)) A spectral doublet has

\lambda = 520\ \mathrm{nm}

and

\Delta\lambda = 0.4\ \mathrm{nm}

. Find the minimum number of grating lines

N

needed to resolve it in first order.