Profilometry by spectral encoding of the optical axis

Herve Perrin; Patrick Sandoz; Gilbert M. Tribillon

doi:10.1117/12.195933

12 December 1994 Profilometry by spectral encoding of the optical axis

Herve Perrin, Patrick Sandoz, Gilbert M. Tribillon

Author Affiliations +

Proceedings Volume 2340, Interferometry '94: New Techniques and Analysis in Optical Measurements; (1994) https://doi.org/10.1117/12.195933
Event: International Conference on Interferometry '94, 1994, Warsaw, Poland

Abstract

A scanning optical profilometer without sample displacement along the optical axis has been developed. Light coming from a wide spectrum light source is focused onto the inspected surface through a Fresnel lens. Because of its dispersive properties, the foci are distributed along the optical axis as a function of wavelength. The reflected light is focused on a filtering pinhole like in confocal microscopy. The only wavelength exactly focused on the surface is transferred through this pinhole to the detection unit. The detected light is analyzed through a spectroscopic device and the surface height is deduced from the wavelength for which the light intensity is maximum. This punctual measure is repeated for each surface point by a lateral scanning of the surface. With respect to other focus sensing profilers, we replace a mechanical z displacement of the sample by a spectral inspection of the detected light. The setup and some experimental results are presented.

Citation Download Citation

Herve Perrin, Patrick Sandoz, and Gilbert M. Tribillon "Profilometry by spectral encoding of the optical axis", Proc. SPIE 2340, Interferometry '94: New Techniques and Analysis in Optical Measurements, (12 December 1994); https://doi.org/10.1117/12.195933

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