Abstract
Divergence of the incident x-ray beam produces appreciable phase differences between different parts of a crystal, even in the size range for which line broadening occurs. The broadening due to this phase difference is calculated. It is ordinarily negligible, as the increase in the width of the line is of the order of 1.6 t cos θ, where t3 is the volume of a crystal and θ is the Bragg angle. The special case of film and source equidistant from the crystal is investigated in greater detail.