Abstract

A simple volumetric thickness measurement method for in-line high-speed inspection is proposed. With a color camera alone, spectrally resolved reflectance in a spatial domain is obtained: a Bayer filter spectrally resolves the reflected signal, and a CMOS sensor acquires three multi-spectral reflectances from RGB data at a single shot. To determine an accurate thickness, a modified reflectance is derived to convert a conventional spectral reflectance throughout a wavelength domain into an adequate form in an RGB domain by considering the characteristics of wide-band multi-spectral acquisition. The proposed method is validated by the measurement of a uniformly deposited ${\mathrm{SiO}}_2$ film and a tapered ${\mathrm{SiN}}_x$ film.

© 2018 Optical Society of America

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