Media noise suppression by multimodal optical disc readout

Kimihiro Saito

doi:10.1117/12.2593573

7 September 2021 Media noise suppression by multimodal optical disc readout

Kimihiro Saito

Proceedings Volume 11828, ODS 2021: Industrial Optical Devices and Systems; 118280C (2021) https://doi.org/10.1117/12.2593573
Event: SPIE Optical Engineering + Applications, 2021, San Diego, California, United States

Abstract

To increase the capacity of optical disc systems, various techniques are available such as improvements of optical readout channels, signal processing method and recording media. Although the recorded information is digital but rather analog like readout signal is adopted for current optical disc systems. The partial response readout has been used in Bluray disc systems. As an alternative technique, we have reported an application of orthogonal frequency division multiplexing to optical disc systems. In such technologies the readout sampling intervals are longer than the information bit rate. Multi-level signal is employed instead to achieve high information density so that the signal to noise ratio is critical to determine the recording density. The kinds of noise in optical disc signal can be classified to thermal (amplifier), shot and medium. The first two are basically random. Those noise signals vary at different readout events so that they can be suppressed by averaging plural readout from the same position. But this technique is helpless for medium noise because it is created in manufacturing or recording processes. However the medium noise may have a different character from the recorded information because of the difference between the processes to create them. For example, the reflectance change of the information marks is different from the surface roughness of the disc noise. Actually several readout channels such as divided photo detectors, multi-wavelength illumination and optical filters enable us to derive various characteristics of signals from readout media. Some methods and calculated results to suppress the medium noise by using such multimodal readout will be discussed in this paper.

Conference Presentation

Citation Download Citation

Kimihiro Saito "Media noise suppression by multimodal optical disc readout", Proc. SPIE 11828, ODS 2021: Industrial Optical Devices and Systems, 118280C (7 September 2021); https://doi.org/10.1117/12.2593573

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