Light concentration efficiency of diffractive lenses with overlapping apertures

Diffractive lenses with overlapping apertures enable a dense spot-wise illumination with high aperture foci, which is not achievable with traditional refractive lens arrays. However, the increased density of illumination spots requires a spatial overlap of the focussing wavelets in the plane of creation. This spatial overlap is feasible due to the nature of diffractive optics. In this contribution the effects of the overlap onto the light concentration efficiency are presented and compared to ideal focussing wave fronts. This is done for the ideal analytic as well as for the quantized and binarized DOE, arising from fabrication requirements.