Method and system for measuring deflection angle of a beam of light reflected from a disk to determine tilt of the disk
US5815255A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 14, 1997 |
| Grant date | Sep 29, 1998 |
| Priority date | — |
| Expiry date | Feb 14, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/26
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and system are provided for measuring a two-dimensional deflection angle of a beam of light reflected from a disk having unknown radial and tangential tilt components by first generating reference data relating to known tilt of a reference disk and then processing the reference data with electrical signals from a two-dimensional photodetector to obtain values related to the deflection angle and the unknown radial and tangential tilt components. The photodetector is preferably a semiconductor photodiode having an active area which measures position of radiant energy in a spot of light focused in a detector plane by a focusing lens. A signal processor including a computer system programmed in accordance with a software algorithm compensates for interaction between X and Y axes of the active area of the photodiode to compensate for alignment errors or tolerances, not only up, down, left and right, but also for rotational errors as well. In this way, the method and system can utilize a single small, relatively low cost semiconductor photodiode for both radial and tangential measurements of the same spot of light.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.