Three-dimensional superresolution by annular binary filters

We present a new family of annular binary filters for improving the three-d imensional resolving power of optical systems. The filters, whose most impo rtant feature is their simplicity, permit to achieve a significant reductio n, both in the transverse and in the axial direction, of the central lobe w idth of the irradiance point spread function of the system. The filters can be used for applications such as optical data storage or confocal scanning microscopy. (C) 1999 Elsevier Science B.V. All rights reserved.