Reduced noise sensitivity method and apparatus for converting an interferogram phase map to a surface profile map
US6738511B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 4, 2000 |
| Grant date | May 18, 2004 |
| Priority date | — |
| Expiry date | Jul 30, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B9/02083
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In the process of converting an interferogram phase map to a surface profile, in the absence of tilt, a histogram of occurrences of phase values is created from phase data. Useful data are identified in bins with contents that exceed a threshold value. Where useful data wrap around the end of the histogram, a selected amount of phase shift is added to the phase data to move them all within the ends of the histogram. Where tilt is present, the phase data are differentiated to produce slope data and a histogram of occurrences of slope values is created. A best-fit amount of tilt is determined from the slope histogram by selecting the bin at the average between two points on the histogram curve that are a predetermined percentage of the maximum height of the curve. Thereafter, the best-fit tilt is subtracted from the original phase data to eliminate tilt.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.