The wafer mapping option includes a precision x - y stage(50X50mm, 100X100mm, 150X150mm or 200X200mm) with computer controlled operation. An extension of the software provides predefined and user defined patterns, auto return positioning and graphical display of the data maps. The step resolution is up to 0. 4 um. For single transparent films the homogeneity of the thickness and refractive index can be displayed graphically as a color-scale plot, a contour plot or a 3D plot.