Super-resolution in optical data storage

In this paper we summarize how fundamental work on the theory of optical im aging performed by our research group over a number of years has led to exp erimental developments, using specially calculated image-plane masks, which have confirmed that optical resolution in high-aperture microscopy, both c oherent and incoherent (fluorescence microscopy), can reach nearly twice th e conventional Rayleigh limit. In particular, we give a detailed treatment of our current work on the application of these ideas to the active area of high-density optical data storage on compact discs (digital versatile disc s (DVDs)). A conventional optical disc can be regarded as a coherent-light confocal scanning microscope and our general theories thus show the feasibi lity of 'superdense' optical data-storage systems. The achievement of near twice the Rayleigh limit for DVDs in the entertainment sector is important at the present lime since this would enable full-length motion pictures to be read on an uncomplicated reader rather than the two-layer or double-side d reading systems now being promoted. Optical discs which use fluorescent m aterial are also being proposed and our resolution enhancements will also a pply to these.