Single snap-shot fringe projection system
US9958251B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 3, 2016 |
| Grant date | May 1, 2018 |
| Priority date | — |
| Expiry date | Aug 4, 2036 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B2290/70
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A cycloidal diffraction waveplate is combined with a pixelated phase mask (PPM) sensor in a dynamic fringe-projection interferometer to obtain phase-shifted interferograms in a single snap-shot camera operation that provides the phase information required to measure test surfaces with micrometer precision. Such mode of operation enables a portable embodiment for use in environments subject to vibration. A shifting mechanism coupled to the cycloidal waveplate allows temporal out-of-phase measurements used to remove noise due to test-surface characteristics. Two or more pixels of each unit cell of the PPM are combined to create super-pixels where the sum of the phases of the pixels is a multiple of 180 degrees, so that fringes are eliminated to facilitate operator focusing. By assigning colors or cross-hatch patterns to different ranges of modulation measured at the detector, the areas of best focus within the field of view are identified quantitatively to ensure measurements under best-focus conditions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.