Multilayer reflection microhologram storage in tape media

摘要: Digital data bits are stored as discrete-level reflection microholograms in a multi-depth digital optical storage system. Reference and signal beams incident counterpropagating geometry on opposite faces of tape. The at the coinciding focus reference beams. holograms diffraction limit high-N.A. optics, have relatively high grating frequencies small sizes. Dynamic aberration compensators correct for depth-varying spherical imparted to by medium. Multiple mutually-incoherent lasers used parallel retrieval increase transfer rates. Achievable densities signal-to-noise ratios substantially higher than index-perturbation or transmission hologram methods.