Two point resolution in incoherent imaging

The formalism for incoherent imaging of two points separated by the Sparrow criterion is investigated in two and three dimensions. Two and three dimensional imaging enables us to distinguish between a single point object and a two point object better than from the one dimensional information. Projections of the two point object, performed by integrating along the axial direction, are shown to improve the observed resolution especially for low NA non confocal systems. There are however a number of different objects, whose images are shown to be virtually indistinguishable. Therefore, resolution measures should only be used in the presence of knowledge about the class of objects being imaged.