Information storage and retrieval for probe storage using optical diffraction patterns

J.W. van Honschoten, Henri W. de Jong, W.W. Koelmans, Thomas P. Parnell, Oleg Zaboronski

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    1 Citation (Scopus)


    A method for fast information retrieval from a probe storage device is considered. It is shown that information can be stored and retrieved using the optical diffraction patterns obtained by the illumination of a large array of cantilevers by a monochromatic light source. In thermo-mechanical probe storage, the information is stored as a sequence of indentations on the polymer medium. To retrieve the information, the array of probes is actuated by applying a bending force to the cantilevers. Probes positioned over indentations experience deflection by the depth of the indentation, probes over the flat media remain un-deflected. Thus the array of actuated probes can be viewed as an irregular optical grating, which creates a data-dependent diffraction pattern when illuminated by laser light. We develop a low complexity modulation scheme, which allows the extraction of information stored in the pattern of indentations on the media from Fourier coefficients of the intensity of the diffraction pattern. We then derive a low-complexity maximumlikelihood sequence detection algorithm for retrieving the user information from the Fourier coefficients. The derivation of both the modulation and the detection schemes is based on the Fraunhofer formula for data-dependent diffraction patterns. The applicability of Fraunhofer diffraction theory to the optical set-up relevant for probe storage is established both theoretically and experimentally. We confirm the potential of the optical readout technique by demonstrating that the impairment characteristics of probe storage channels (channel noise, global positioning errors, small indentation depth) do not lead to an unacceptable increase in data recovery error rates. We also show that for as long as the Fresnel number F0.1, the optimal channel detector derived from Fraunhofer diffraction theory does not suffer any significant performance degradation.
    Original languageUndefined
    Pages (from-to)1-14
    Number of pages14
    JournalJournal of Applied Physics
    Issue number104309
    Publication statusPublished - 23 Nov 2011


    • light sources
    • maximum likelihood sequence estimation
    • EWI-20992
    • TST-uSPAM: micro Scanning Probe Array Memory
    • TST-SMI: Formerly in EWI-SMI
    • Fraunhofer diffraction
    • Fresnel diffraction
    • Information Retrieval
    • Optical polymers
    • information storage
    • METIS-281637
    • IR-78982

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