Patent ID: 7430049

Claim:
Process for scanning a surface of a substrate, comprising: projecting light onto a reflective surface having a test pattern formed thereon; directing reflected light including a test pattern image of the test pattern that is reflected from the reflective surface onto the surface of the substrate; capturing a reflected image of the test pattern image that is reflected from the surface of the substrate when the substrate is in a dynamic state; extracting by a phase stepping process local phases in two directions from the captured reflected image; and determining optical properties of the surface of the substrate by calculating variations in local slopes by digital processing from the local phases, the extracted local phases being compared to reference phases for deducing phase variations which are converted by a sensitivity factor to form variations in local slopes, and to deduce, from said variations in local slopes, variations in curvature by a digital processing involving derivation or variations in altitude of the surface of the substrate by a digital processing involving integration.