Deconvolution of local surface response from surface topography in optical profilometry by a dual-scan method

Summary form only given. In optical profilometry the measured raw data represent a convolution of local surface response to the probing light and surface topography. For example, the reflectivity variation or the spatial gradient of the surface modulates the profilometric signal. Almost all the existing methods use interferometric lock-in techniques to eliminate the effect of local surface modulation. However, these methods employ complicated servo-feedback circuits and/or data-coding procedures, and most of them are not general enough to be useful for other profilometries such as atomic force microscopy (AFM) or near-field optical microscopy. We demonstrate a dual-scan method with a new nanometer surface profiling and imaging technique, differential confocal microscopy (DCM). DCM is capable of fast open-loop measurements with a height resolution as great as 2 nm.