Real-time effective-wavelength error correction for HDVSI
US7956630B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Apr 23, 2010 |
| Grant date | Jun 7, 2011 |
| Priority date | — |
| Expiry date | Apr 23, 2030 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/2441
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An error correction for effective-wavelength variations is implemented by adjusting the filter parameters of the quadrature demodulation algorithm of a high definition vertical scanning process using a phase step that accounts for phase-step changes associated with variations in the effective wavelength irradiating the sample when the surface is curved. The nominal phase step is replaced in the filter with an actual phase step size that includes a phase parameter generated for each pixel by calibration or modeling of a specific type of surface. This substitution eliminates all errors produced by surface-dependent variations in the effective wavelength of the irradiating light.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.