All Problems Diffraction of Light
Problem 5.111
A plane monochromatic light wave falls normally on an opaque half-plane. A screen is located at a distance \(b=100 \mathrm{~cm}\) behind the half-plane. Making use of the Cornu spiral (Fig. 5.19 ), find: (a) the ratio of intensities of the first maximum and the neighbouring minimum; (b) the wavelength of light if the first two maxima are separated by a distance \(\Delta x=0.63 \mathrm{~mm}\).
5.111. (a) \(I_{\max } / I_{\min } \approx 1.7\) (b) \(\quad \lambda=2(\Delta x)^{2} / b\left(v_{2}-v_{1}\right)^{2}=\) \(=0.7 \mu \mathrm{m},\) where \(v_{1}\) and \(v_{2}\) are the corresponding values of the parameter along Cornu's spiral.