Claims
- 1. An optical disk to be used for calibrating a far-field detector of an optical disk drive, having an axis of rotation and a predetermined annular outwardly-facing surface area disposed on a circular (transparent) substrate, said annular surface area comprising radially-outermost and radially-innermost annular planar highly-reflective areas and a grooved signal-storing area for storing machine-sensible signals disposed radially between said planar highly-reflective areas; comprising:
- said highly reflective areas respectively having a predetermined high optical reflectance, said outwardly-facing surface area being subject to having predetermined undesired surface perturbations that interfere with a light beam impinging upon and being reflected from said annular surface area; and
- low reflectance means on a predetermined one of said highly reflective areas for simulating said predetermined undesired surface perturbations and having a reflectance less than said predetermined high optical reflectance, said low reflectance means have first and second circumferentially spaced-apart radially-elongated portions disposed at a same radius of said annular surface area, said portions being symmetrically disposed about a given radial line of said annular surface area.
- 2. The optical disk set forth in claim 1, further comprising:
- said intermediate grooved signal-storing portion having a spiral groove that constitutes a spiral machine sensible track, said machine sensible track having a radial extent of not greater than five microns, said radially innermost and outmost annular planar highly reflective areas being non-grooved;
- said first and second portions respectively having a radial length an order of magnitude greater than the radial extent of said machine addressable track.
- 3. The optical disk set forth in claim 2, further comprising:
- said first and second portions being disposed to be radially-outwardly diverging at an angle of 90 degrees and said first and second portions respectively diverging with respect to said given radial line at 45 degree angles.
- 4. The optical disk set forth in claim 2, further comprising:
- said low reflectance means being disposed on said radially outermost high reflectance area and being disposed radially outward away from said intermediate annular grooved area.
RELATED APPLICATION
This application is a division of Ser. No. 08/723,155, filed Sep. 30, 1996 and now is U.S. Pat. No. 5,777,962, that is a division of Ser. No. 08/250,320, filed May 27, 1994, now U.S. Pat. No. 5,627,818, that is a continuation of Ser. No. 07/960,033, filed Oct. 13, 1992, now abandoned.
US Referenced Citations (10)
Foreign Referenced Citations (3)
Number |
Date |
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2136612 |
Nov 1972 |
FRX |
1552251 |
Feb 1977 |
GBX |
9014667 |
Nov 1990 |
WOX |
Divisions (2)
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Number |
Date |
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Parent |
723155 |
Sep 1996 |
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Parent |
250320 |
May 1994 |
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Continuations (1)
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Number |
Date |
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960033 |
Oct 1992 |
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