Interferometric roll-off measurement using a static fringe pattern
US9829310B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 30, 2016 |
| Grant date | Nov 28, 2017 |
| Priority date | — |
| Expiry date | Jun 30, 2036 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T2207/30148
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus for measuring the surface contour of a target area of a substrate has a light source to emit a measurement light beam. A beam splitting element defines a measurement axis and a reference axis. A substrate holder disposes the target area along the measurement axis and tilted away from normal incidence, about a tilt axis that orthogonally intersects the measurement axis, according to a predetermined tilt angle that is a function of the measurement light beam wavelength. An imaging sensor records a fringe pattern generated from the measurement light beam and a reference light beam. A computer extracts frequency profiles from the recorded fringe pattern, each profile taken in a direction that is orthogonal to the direction of the tilt axis, wherein the programmed instructions further compute changes in the contour of the target area surface according to the frequency profiles.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.