A DOE is an optical device – essentially a diffractive grating that allows splitting of a single beam from a coherent source (laser) into multiple beamlets using the effects of diffraction. In practice the DOE is usually a piece of transparent medium (glass, plastic, fused silica, etc.) with embossed pattern on its surface. A single laser beam is directed to the thin element and small variations in thickness of at different points in the element perturb the phase of electromagnetic waves to allow interference to create a specific final output pattern of beamlets, for instance a linear array as in Figure 1 (O'Shea, 2004).