Thickness measurement of thin transparent plates with a broad-band wavelength scanning interferometer

Year: 2004

Authors: Maddaloni P., Coppola G., De Natale P., De Nicola S., Ferraro P., Gioffrè M., Iodice M.

Autors Affiliation: Istituto Nazionale di Ottica Applicata, Via Campi Flegrei 34, 80078 Pozzuoli (Napoli), Italy;
Istituto per la Microelettronica e Microsistemi-Consiglio Nazionale delle Ricerche, Via P. Castellino 111, 80131 Napoli, Italy;
Istituto di Cibernetica-Consiglio Nazionale delle Ricerche, Via Campi Flegrei 34, 80078 Pozzuoli (Napoli), Italy

Abstract: A novel broad-band telecom laser source is used to realize a lateral-shear scanning-wavelength interferometer for measuring the thickness of thin plates. We show that the wide tunability range allows to detect samples down to tens of microns with a relative uncertainty of less than 0.5% and a resolution of about 1 nm. A comparable accuracy in the thickness characterization of double-layer structures is also demonstrated. In turn, the wide tunability range needs the dispersion law of the materials to be taken into account in the model for correct thickness evaluation.

Conference title:

KeyWords: Cameras; Characterization; Charge coupled devices; Fiber lasers; Radiation; Refractive index; Scanning; Silicon; Spectrophotometry; Dielectric layers; Dispersion; Relative shifts; Thin plates; Interferometers
DOI: 10.1117/12.544955

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