METHOD AND DEVICE FOR DETECTING SUBSTANCES ON SURFACES

摘要

A testing device determines the presence of substances on a surface using an imaging sensor positioned at a known vantage point to the surface. A liquid dispenser deposits a liquid drop on the surface. A data generator after a first time interval for allowing the liquid drop to stabilize on the surface detects via the imaging sensor a geometric characteristic of the liquid drop that is related to a first equilibrium contact angle of the liquid drop to the surface. The data generator after a second time interval detects via the imaging detector the geometric characteristic of the liquid drop that is related to a second equilibrium contact angle. The data generator compares the first and second contact angle and determines a contamination on the surface that is soluble in the liquid drop in response to a change between the first and second contact angles.