Precision Measurement of Optical Disc Media and More

Optical Disc Media

DiscTrack Plus is a critical tool for testing optical discs. It reveals pit and groove geometry, track pitch, wobble, jitter and more. It is a crucial tool for the development of new formats, when disc players are scarce or unavailable. It is the perfect complement to electrical disc analyzers in process optimization and troubleshooting to support production.  DiscTrack Plus supports more than half the world’s production of DVDs amd Blu-Ray discs (as of 2013).

Magnetic Disk Media

Pre-patterned media (“Bit Patterned Media” and “Discrete Track Recording”) are currently the subject of much research in the hard disk industry.  Pre-patterned media are analogous to optical disc media and DiscTrack Plus should be used to make very precise and accurate measurements from SEM and AFM images of the media masters, stampers or actual media. [updated 9/23/2008]

  • Magnetic Media Publications
    • “Picometer-scale Accuracy in Position Measurements of NanoDots in a 525 Gdot/in2 Pattern”, [3.2 MB pdf file], Donald A. Chernoff and David L. Burkhead.  Poster presented at Diskcon 2008, 9/17-18/2008.
      Patterned magnetic media require nanometer control of track pitch and feature size variation. Nanometer control implies picometer metrology. We use an ordinary open-loop AFM with additional offline calibration and measurement software to measure pitch and pitch variation.         In systematic measurements on a 144 nm pitch 2-Dimensional square grating (31 G dot/in2) we measured individual pitch variation of 0.55 nm (1 σ) and average pitch to an accuracy of 40 pm (1 σ).         Accuracy was confirmed by optical diffraction measurements at a national standards laboratory.
      SEM of a 76 nm pitch 1-dimensional grating (334k tracks/in) showed individual pitch variation of 167 pm (1 σ).
      SEM of a 35 nm pitch 2-dimensional grating (525 G dot/in2) showed individual pitch variation of 80 pm (1 σ). This precision suggests we can measure the average pitch to an accuracy of 10 pm (1 σ).
    • High Accuracy Measurements of Patterned Media“, [590 kB pdf file] poster presented at DiskCon, September, 2007.  See also  “Picometer-scale accuracy in pitch metrology by optical diffraction and atomic force microscopy” [1 MB pdf file] and Measuring_Nanometers-with-Picometer_Accuracy [4MB pdf], which give further discussion of our accuracy claims.

Fundamental Measurement Patents

Everything you need to know but were afraid to ask about calibration and measurement from X to Z:

  • “High precision calibration and feature measurement system for a scanning probe microscope”. US Patent 5,644,512, filed March 4, 1996, issued July 1, 1997. Inventors: Donald A. Chernoff and Jason D. Lohr. Text (78 kB) Scan (3554 kB)
  • “High precision calibration and feature measurement system for a scanning probe microscope.” US Patent 5,825,670, filed March 5, 1997, issued October 20, 1998. Inventors: Donald A. Chernoff and Jason D. Lohr. Text (160 kB) Scan (6777 kB)