1 / 16

Optical Data Storage

Optical Data Storage. By Ken Tatebe 2004.11.1. Outline. Basic Technology CD: Properties and Capabilities DVD: Comparison to CD What’s makes DVD’s better? Comparison to other contemporary data storage technologies Future directions. First Optical Storage Techniques.

kevin-long
Download Presentation

Optical Data Storage

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Optical Data Storage By Ken Tatebe 2004.11.1

  2. Outline • Basic Technology • CD: Properties and Capabilities • DVD: Comparison to CD • What’s makes DVD’s better? • Comparison to other contemporary data storage technologies • Future directions

  3. First Optical Storage Techniques

  4. 20th Century: The Compact Disc • Patented in 1970 by James T. Russell as a means for durable audio data storage. • First digital optical data storage; inspired by punch cards and magnetic storage devices. • Mass production starts in 1985 by Philips and Sony. • Gives practical use to Reed – Solomon Error Correction. • Data Density: ~ 1Mbyte/mm2

  5. Tracking and Error Correction • Diagonally astigmatic lens coupled with quadrant photocell. • Difficult to keep focus stable across all freq. • 1 mm surface spot size due to high NA • Reed - Solomon correction codes • Over-sampled polynomial using data as coefficients

  6. DVD: Improvements to CD

  7. Road to the DVD • Innovations: • Dual layer • Increased numerical aperture • Decreased depth of focus • Signal to noise • Tracking • Data Density: ~7 MByte/mm2

  8. Dual Layer Technology • Benefits • Increased durability • Increased capacity • Detriments • Decreased S/N • Decreased data density

  9. Numerical Aperture • NA = n sin(q/2) • Spot size = l/NA

  10. Depth of Focus • DoF = l/NA2 • Determines spacing of layers • Affects S/N; places an upper limit on NA.

  11. Noise Tolerances • Coma Aberrations • Laser more stable at -135 db/Hz • Eccentricity 100 micron down from 140 micron • Surface aberration of 0.033 l down from 0.07 l

  12. Hard drives

  13. Future Data Disc Advances

  14. Non-linear Upgrades • 2 – Photon absorption to decrease depth of field for more layers • Magnetic Super-Resolution: 100 nm spot size. • Separate layers by narrow spectral response. • Shorter wavelength (freq. doubled?)

  15. Volumetric Storage • “K – Vector” Addressing: a.k.a. Holographic addressing • 2 beam intersection: issues with reaching diffraction limits • Interferometer based path length addressing

  16. References • Optical Data Storage. Coufal, Hans, Geoffrey Burr: International Trends in Optics, 2002. • DVD Focus Control. Lincoln, Bo: Lecture notes. • Smith, Steven W. The Scientist and Engineer’s Guide to Digital Signal Processing. San Diego: California Technical Publishing, 1997. • Usbyte.com • Pioneer.co.jp • Optical-disk.com • Hecht, Eugene. Optics. Reading: Addison Wesley Longman, 1998. • Magnetic Super Resolution: Fujitsu.

More Related