Optical topometry of surfaces with locally changing materials, layers, andcontaminations. Part 1: Topographic methods, based on two-beam interferometry

Conventional topometry, applied to surfaces with locally changing materials can result in significant errors in the measured heights. A new theoretica l approach is developed for the case of two-beam interferometry. Applied to some surface structures-gold on glass, oil on steel and SiO2 on Si-importa nt effects of contrast and phase variations are brought to attention. They are explained by a new theory using the complex contrast. Ways for surface correction procedures are outlined.