Some properties of the single-crystal rocking curve in the Bragg case

In the present article (i) a new formula for the single-crystal rocking curve for both the centrosymmetric and polar Bragg case is given; (ii) a geometrical construction is derived, whence many properties of the rocking curve are easily visualized; (iii) the different analytical expressions introduced by several authors are shown to be a consequence of different definitions of the variable `y'.