In a shadow mask-substrate alignment method, a substrate and a shadow mask each include a grate having a plurality of bars in spaced relation, wherein for each grate, each pair of spaced bars of each grate is separated by a gap. The spacing between at least three adjacent gaps is different or not of constant pitch, and at least one grate includes a gap that extends therethrough. The grate of the substrate and the grate of the shadow mask are positioned in a light path. Thereafter, the orientation of the substrate, the shadow mask, or both are caused to be adjusted to position the grate of the substrate, the grate of the shadow mask, or both until a predetermined amount of light or range of an amount of light on the light path passing through one or both of the grates is received by a light receiver.