Diffractive optical element, confocal microscope and method for designing a diffractive optical element

The invention relates to a diffractive optical element (1) for generating from an input light beam (65) a plurality of smaller light spots (66) on a target surface (21), comprising a material layer (10) having a plurality of at least first and second subareas (11, 12, 13) having any of first and second absorption coefficients or first and second thicknesses, wherein the arrangement of said first and second subareas (11, 12, 13) on the material layer (10) is obtained by calculating the field distributionuw(x,y) in a plane (19) defined by the material layer (10) for a single light spot (66) by means of a Rayleigh-Sommerfeld-Integral, arranging and overlapping said field distributionuw(x,y) in said plane (19) for a predetermined arrangement (67) of a plurality of light spots (66), adding a plane-wave component W to the overlapped field distributionu0(x,y) to get a plane-wave-combined field distributionup(x,y), and determining the phasefB(x,y) and/or the amplitude of the plane-wave-combined field distributionup(x,y) at least in the subareas (11, 12, 13). Furthermore, the invention relates to a confocal microscope (9) comprising such an element and a method for designing at least one diffractive optical element.