Method and system for realising a correlation, at least in space, of the focal fields of at least two electromagnetic beams at the focus of an optical focusing element, wherein a specific spatial distribution in amplitude, phase and polarisation of a focal field combined from the focal fields is generated and a physical response to the generated focal field in a sample placed at the focus is measured. A one- or multi-dimensional spatial shift in the focal field of at leat one of the at least two beams is introduced with respect to the focal field of others of the at least two beams. The relative phase of the beams is controlled by a (periodic) variable optical path length for at least one of the beams. The physical response, as a consequence of a physical process in the sample or as a consequence of scattering of the focal field at the sample, is detected, optionally with the aid of a specific collection function which is a combined image of a specific space/time distribution of the physical response at the focus of the focusing element. Microscopic imaging with increased lateral and/or axial resolution is possible when the physical response of a sample subjected to the above-mentioned focal fields is detected by means of a collection function, which may or may not be specific. In addition, the quantitative structure in space and time, related to the point spread function, of the focal field of the focusing element on and alongside the optical axis thereof can be determined in terms of amplitude, phase or polarisation.
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