Extraction of surface topography features of optical elements by contourlet transform

With the development of precision optical engineering, higher manufacturing qualities are demanded for advanced optical systems. The characterization of the surface topographies of optical elements is required to be more specific and more comprehensive. In this paper, the contourlet transform is adopted to extract the topological features of optical elements. The performance of the contourlet transform(CT) is analyzed carefully. The multiscale analysis techniques based on contourlet transform for peak/pit extraction, tool trace identification and sharp edge detection on non-smooth microstructured optical surfaces were shown. The experimental examples are given to demonstrate the validity of the proposed method.