Category Archives: diffraction


The previous post on the Gaussian beam noted that this beam is a solution to the paraxial wave equation and thus only accurate for small divergence angles. The limit given in [1] was $w_0 \gt 2\lambda/\pi$ or $\theta \lt 0.5\mathrm{rad}$ or $\approx 29^\circ$. The Gaussian beam model is of course not exact up to that […]

Scalar Diffraction – Fourier

In an earlier post we had a look at various diffraction formalisms that either originated in the Huygens-Fresnel principle or led to essentially the same results. The principle modeled a field distribution in a aperture (or on a surface) as a source of infinitely many spherical waves whose amplitudes and phases were prescribed by the […]

Scalar Diffraction – Imagery

In this post on the principles of scalar diffraction there were quite a number of integral expressions for diffraction of light, starting from the Huygens-Fresnel principle and applying various degrees of approximation. Integral formulations are usually very abstract and not very illustrative. However, with today’s available computer power we can turn these integrals into…

Scalar Diffraction – Huygens, Fresnel, Fraunhofer

One can work years in fiber optic communications and not really have to care about diffraction, but when working with free-space light propagation and/or illuminated surfaces it’s better to know the difference between your Fresnel and your Fraunhofer diffraction, and what the heck the Huygens-Fresnel principle is all about.