LETTERS AND COMMENTS: Comment on 'Reflection, refraction and multislit interference'

It is indicated that the generalized interference equation, obtained using the Dirac notation applied to an N-slit interferometer, has already been applied to derive the equation of the diffraction grating, the law of refraction and the law of reflection. The applicability of the Dirac approach to describe interference of large number of indistinguishable photons is also explained.