Free-space diffraction
= Free-space diffraction
In a homogeneous medium, a paraxial envelope satisfies $E_x=i\Delta_\perp E/(2k)$. This free-space diffraction spreads transverse Fourier modes by the phase factor $\exp(-ix|\mathbf p|^2/(2k))$.
= Free-space diffraction
In a homogeneous medium, a paraxial envelope satisfies $E_x=i\Delta_\perp E/(2k)$. This free-space diffraction spreads transverse Fourier modes by the phase factor $\exp(-ix|\mathbf p|^2/(2k))$.