Revealing the backbone structure of B-DNA from laser optical simulations of its X-ray diffraction diagram

A visible laser and a set of nine specially designed diffraction gratings held on a single slide have been used to build up progressively a classroom optical simulation of the diffraction of X-rays by a B-DNA fiber. The nine optical transforms allow understanding, without recourse to helical diffraction theory, of how the prominent features of the observed diffraction pattern arise from each of the structural parameters of the DNA backbone.