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28 June 1999 Optically equalized PRML channels for high-density optical data storage
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The use of optical super-resolution techniques to improve the performance of conventional far-field readout systems in optical data storage has generated much recent interest. The insertion of amplitude shading bands in the illumination (incident) path and the collection (reflection) path has been investigated by various researchers as a means for reducing inter-symbol and/or cross-track interference. Phase-shifting apodizers have also proved useful in a variety of storage formats. All of these methods modify in some way the optical transfer function of readout head. From this point of view optical super-resolution can be thought of as a form of optical equalization. This opens up the possibility for designing the readout head to incorporate optically some of the equalization/filtering functions that are normally performed electronically. A particularly exciting prospect would be a readout head that generated directly a partial response type readout waveform, without the need for electronic equalization. In this paper we show that this is indeed possible, using simple rectangular shading bands inserted into the collection path to equalize optically to PR(a,b,b,a) type targets.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
C. D. Wright, S. D. Jepson, and Paul W. Nutter "Optically equalized PRML channels for high-density optical data storage", Proc. SPIE 3864, Joint International Symposium on Optical Memory and Optical Data Storage 1999, 386433 (28 June 1999);

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