Method and apparatus for profiling surfaces using diffractive op

Details Method and apparatus for profiling surfaces using diffractive op Method and apparatus for profiling surfaces using diffractive op

1994-11-07

1996-06-11

Turner, Samuel A.

Optics: measuring and testing

By dispersed light spectroscopy

Utilizing a spectrometer

356359, G01B 902

Patent

active

055261167

ABSTRACT:
Optical system for measuring surface topography, comprised of a light source (30), a diffractive optical assembly (70, 72, 73) comprised of two or more diffraction gratings, holograms or like diffractive optics (120, 130; 122, 132; 123, 133), electronic detection means and digital signal processing means (10, 110) for determining surface height from interference data. The diffractive optical assembly (70, 72, 73) divides the incident light into two beams (150, 160; 152, 162; 153, 163), which subsequently impinge upon the object (20) at the same place on The object surface (70) but at two different angles of incidence. After reflection from the object surface, the beams pass separately back through the diffractive optical assembly (70, 72, 73), after which they combine once again and form an interference pattern representative of the surface topography. The equivalent wavelength of the resultant interference pattern is much greater than the illumination wavelength.

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