Recording device of master disk for information recording medium
US7053394B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Aug 7, 2002 |
| Grant date | May 30, 2006 |
| Priority date | — |
| Expiry date | Aug 21, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/261
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Two light beams are incident on the same position on a surface of an object (105) to be measured obliquely from upper sides facing each other, and positions at which the reflecting light beams are incident on respective predetermined detection surfaces are detected by position detectors (102 and 104) for outputting respectively as position detection signals. The displacement of the surface to be measured is detected by obtaining the difference between or the sum of respective position detection signals so as to cancel the components in the directions opposite to each other out of the components indicating changes from the reference position included in respective position detection signals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.