Single snap-shot fringe projection system

A fringe-projection interferometric method comprising the following steps:

• providing a light source;
• passing a beam from the light source through an orthogonal polarizer to produce two orthogonally polarized beams;
• focusing a combined beam of said orthogonally polarized beams on a test surface, said combined beam being projected on the test surface in orthogonally polarized states such that virtual fringes are imaged on the test surface;
• injecting said combined beam, after reflection from the test surface, into a dynamic imaging system including a plurality of optical elements adapted to produce predetermined phase shifts between the orthogonally polarized beams, thereby producing a plurality of phase-shifted interferograms, said dynamic imaging system including a light detector in optical alignment with each of said phase-shifted interferograms;
• and
• performing with a processor an interferometric measurement of the test surface based on said spatially phase-shifted interferograms.

A dynamic fringe-projection interferometer comprising:

• a light source;
• a cycloidal diffractive waveplate producing two orthogonally polarized beams from an incident beam received from the light source;
• a focusing element for imaging a combined beam of said orthogonally polarized beams on a test surface, said combined beam being projected on the test surface in orthogonally polarized states such that virtual fringes are imaged on the test surface;
• a pixelated phase mask adapted to receive said combined beam after reflection from the test surface, said pixelated phase mask including a plurality of sets of phase-mask elements, each set being adapted to produce a predetermined phase shift between the orthogonally polarized beams, wherein said combined beam impinges in undivided form upon each of said sets of phase-mask elements along a single optical axis, thereby producing a plurality of spatially phase-shifted interferograms;
• a light detector in optical alignment with the pixelated phase mask, each of said plurality of sets of phase-mask elements being aligned with a corresponding set of detector pixels;
• a phase-shifting mechanism in an illumination path of said incident beam received from the light source, and
• a processor programmed to perform an interferometric measurement of the test surface based on said spatially phase-shifted interferograms.