Photograph of light diffracted by a straightedge.
The intensity distribution follows ${\left|\mathcal{F}\left(x\right)\right|}^{2}$,
where $\mathcal{F}$ is the Fresnel integral (See 7.3.4).
Fresnel integrals have many applications in optics.
The faint circular patterns are additional diffraction
effects due to imperfections in the edge.