1 January 2000 Geometrically desensitized interferometry for shape measurement of flat surfaces and 3-D structures
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Optical Engineering, 39(1), (2000). doi:10.1117/1.602339
Abstract
We construct an interferometer for flatness testing of precision-engineered objects such as rigid disk drive platters, pump parts, and fuel injectors. A pair of phase diffraction gratings illuminate an object simultaneously at two different angles of incidence, resulting in an equivalent wavelength of 12.5 µm. This system operates in standard phase-shifting mode for a height resolution of 0.01 µm with up to 150 µm of surface departure. The <1 s measurement speed, 96-mm viewing aperture, simple mechanical part alignment, and 50-mm working distance are consistent with high-volume production testing. A recently developed coherence scanning mode accommodates even larger departures and discontinuous regions such as step heights.
Peter J. de Groot, Xavier Colonna de Lega, Dave Stephenson, "Geometrically desensitized interferometry for shape measurement of flat surfaces and 3-D structures," Optical Engineering 39(1), (1 January 2000). http://dx.doi.org/10.1117/1.602339
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KEYWORDS
Interferometry

Interferometers

Diffraction gratings

Metrology

3D metrology

Grazing incidence

Optical testing

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