Study on topography measurement of ultra smooth surface

With the development of super precision machining technology, the requirement for the precision of super-smooth surfaces measurement has reached ever-higher levels. In this paper, we adopt the phase-shifting interferential microscope technology, and present a kind of algorithm called Geodesic Erosion which aims at eliminating noises in the wrapping phase image such as abrupt phase changes, holes, points with low modulation, etc. Experiments show that the system is effective to remove noises in the wrapping phase image and successful to achieve the unwrapping phase image. The accuracy of this system may attain nanometer magnitude, while can also meet the topography measurement requirement for the super-smooth surfaces perfectly.