Multiple wavelength fringe analysis for surface profile measurements

Abstract

Interferometry has been widely used for surface metrology because of their precision, reliability, and versatility. Although monochromatic-light interferometery can provide high sensitivity and resolution, but it fails to quantify largediscontinuities. Multiple-wavelength techniques have been successfully used to extend the unambiguous step height measurement rage of single wavelength interferometer. The use of RGB CCD camera allows simultaneous acquisition of fringes generated at different wavelengths. In this work, we discuss details about the fringe analysis of white light interferograms acquired using colour CCD camera. The colour image acquired using RGB camera is decomposed in to red, green, blue components and corresponding interference phase is measured using phase evaluation algorithms. The approach makes the 3D surface measurements faster, cost-effective for industrial applications.

Simultaneous profiling of optically smooth and rough surfaces using dual-wavelength interferometry

“…The major drawbacks associated with 1λ-interferometer are it cannot reveal the shape of a rough surface in out-of-plane configuration and it cannot resolve the discontinuities between smooth and rough surfaces. By adding one more wavelength, these problems associated with single-wavelength analysis can be easily solved [33][34][35][36].…”