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We describe a system for fast three-dimensional profilometry, of both optically smooth and optically rough surfaces, based on scanning white-light techniques. The system utilizes an efficient algorithm to extract and save only the region of interference, substantially reducing both the acquisition and the analysis times. Rough and discontinuous surfaces can be profiled without the phase-ambiguity problems associated with conventional phase-shifting techniques. The system measures steps to 100 µm, scans a 10µLm range in 5 s, and has a smooth surface repeatability of 0.5 nm.

We demonstrate a simple way of increasing the data acquisition and processing speed in a scanning whitelight interferometer for surface topography measurement. The method consists of undersampling interference data and processing the resultant sub-Nyquist interferograms in the frequency domain to create complete threedimensional images. Experimental results on a 20-jrm step height standard show a measurement repeatability of 10 nm.

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