Ewald's Reciprocal sphere lattice To area detector a Incident beam Single crystal Fig.7.11 The illustration of a single crystal showing the orientations of the basis vectors corre- sponding to both the direct (a,b and c)and reciprocal (a*,b*and c*)lattices and the Ewald's sphere.The reciprocal lattice is infinite in all directions but only one octant (where h>0.k >0 and I>0)is shown for clarity