ABSTRACT
These instruments, used both in research labs and on the production floor, are based on a digital microscope equipped with an interferometric objective (from 1× to 115× magnification) and a computer-controlled scan through focus. The precision of the height measurement, levels only possible by using the interference of light, is independent of the numerical aperture of the microscope objective and can reach vertical resolutions down to a fraction of a nanometer. A WLI 3D microscope (see Figure 10.1) functions as regular microscope but delivers height measurements at hundreds of thousands to over a million points simultaneously creating a 3D surface topography measurement.
