Quantitative wavefront measurement using a ronchi test with a phase-shifted sinusoidal grating

Elastic scattering of light reflects an inhomogeneous interface between two media. Applied to surfaces the technique is sensitive to roughness levels in the sub-Angstrom region. This makes it an excellent tool for studying minute changes in the surface structure while processing materials. Examples are given of real-time total integrated scattering applied to stress analysis of metallization films and monitoring of thermal stability of silicides.