In a Young's double-slit demonstration using sodium light ( nm)
PHYSICS · Subjective · Fermi University Physics · Optics & Photonics · Interference and diffraction · Coherence and statistical optics
Optics and Photonics, Ch Two-beam interference and interferometry
Problem
In a Young's double-slit demonstration using sodium light (λ=589 nm), the two slits are d=0.40 mm apart. They are illuminated directly (no lens) by a slit-shaped source a distance Ls=0.15 m in front of the slit plane. Estimate the greatest width ws the source slit may have while still allowing fringes to be seen on a distant screen.