Part A. A Young's double-slit apparatus has slit separation mm and screen distance m,…
PHYSICS · Subjective · Fermi University Physics · Optics & Photonics · Interference and diffraction · Interference and diffraction
Optics and Photonics, Ch Two-beam interference and interferometry
Problem
Part A. A Young's double-slit apparatus has slit separation d=0.25 mm and screen distance L=1.0 m, illuminated by a helium-neon laser at λ=633 nm. A thin sheet of mica, index ng=1.58 and thickness t=8.0μm, is placed over one slit only. (a) By how many fringe widths does the pattern shift? (b) Express this shift in millimetres on the screen. Part B. A Michelson interferometer has a gas cell of length ℓ=8.00 cm in one arm. Filling it with argon at λ1=546 nm (filtered mercury green line) gives N1=100 fringes. (a) Find n−1 for argon at 546 nm. (b) Predict the fringe count N2 at λ2=405 nm, assuming n−1 is unchanged.