Claims
- 1. A method of detecting defects in a magnetic hard disk servo pattern stamper, comprising:
scanning a servo pattern on a stamper with an incident beam; detecting a reflected beam from the stamper to form a detected pattern signal, the reflected beam scattered according to the pattern on the stamper; and comparing the detected pattern against a reference servo pattern signal to identify defects.
- 2. The method according to claim 1 wherein a physical offset of scattered beam depends on the presence or absence of a servo pattern or debris.
- 3. The method according to claim 1 further including:
applying a magnetic field to the stamper; detecting a Kerr rotation of the reflected scattered beam to form a Kerr rotation signal; the Kerr rotation signal having a pattern; and comparing the Kerr rotation signal pattern against a reference Kerr rotation servo pattern signal to identify magnetic defects.
- 4. The method according to claim 2 further including:
applying a magnetic field to the stamper; detecting the Kerr rotation of the reflected scattered beam to form a Kerr rotation signal; the Kerr rotation signal having a pattern; and comparing the Kerr rotation signal pattern against a reference Kerr rotation servo pattern signal to identify magnetic defects.
- 5. The method according to claim 3 wherein the incident beam is linearly polarized light.
- 6. The method according to claim 3 wherein the magnetic field is applied by an electromagnet.
- 7. The method according to claim 1 wherein the reference servo pattern signal is determined by
scanning a known good stamper servo pattern with an incident beam to form a reflected beam scattered by the stamper servo pattern; detecting the amplitude of the reflected beam to form an detected amplitude signal; and forming a reference servo pattern signal comprising a statistical representation of the detected amplitude signal.
- 8. The method according to claim 7 wherein the statistical representation is a Kurtosis value calculated from the amplitude signal detected from at least one servo spoke.
- 9. The method according to claim 7 wherein the statistical representation is a Kurtosis value calculated from the amplitude signal detected from substantially all servo spokes on a track.
- 10. Apparatus for detecting defects in a magnetic hard disk servo pattern stamper, comprising:
means for scanning a servo pattern on a stamper with an incident beam; means for detecting a reflected beam from the stamper to form a detected pattern, the reflected beam scattered according to the pattern on the stamper; and means for comparing the detected pattern against a reference servo pattern to identify defects.
- 11. Apparatus according to claim 10 wherein a physical offset of scattered beam depends on the presence or absence of a servo pattern or debris.
- 12. Apparatus according to claim 10 further including:
means for applying a magnetic field to the stamper; means for detecting a Kerr rotation of the reflected scattered beam to form a Kerr rotation signal; the Kerr rotation signal having a pattern; and means for comparing the Kerr rotation signal pattern against a reference Kerr rotation servo pattern signal to identify magnetic defects.
- 13. Apparatus according to claim 11 further including:
means for applying a magnetic field to the stamper; means for detecting a Kerr rotation of the reflected scattered beam to form a Kerr rotation signal; the Kerr rotation signal having a pattern; and means for comparing the Kerr rotation signal pattern against a reference Kerr rotation servo pattern signal to identify magnetic defects.
- 14. Apparatus according to claim 12 wherein the incident beam is linearly polarized light.
- 15. Apparatus according to claim 12 wherein the magnetic field is applied by an electromagnetic means.
- 16. Apparatus according to claim 10 wherein the reference servo pattern signal is determined by
means for scanning a known good stamper servo pattern with an incident beam to form a reflected beam scattered by the stamper servo pattern; means for detecting the amplitude of the reflected beam to form an detected amplitude signal; and means for forming a reference servo pattern signal comprising a statistical representation of the detected amplitude signal.
- 17. Apparatus according to claim 10 wherein the statistical representation is a Kurtosis value calculated from the amplitude signal detected from at least one servo spoke.
- 18. Apparatus according to claim 10 wherein the statistical representation is a Kurtosis value calculated from the amplitude signal detected from substantially all servo spokes on a track.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. provisional patent application serial No. 60/392,788, filed on Jun. 28, 2002, which is hereby incorporated by reference.
Provisional Applications (1)
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Number |
Date |
Country |
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60392788 |
Jun 2002 |
US |