Wavelet transform as a processing tool in white-light interferometry

Abstract

Results of the application of wavelet transform for signal processing in white-light interferometry are reported. The mother wavelet frequency is chosen to be the light-source correlogram 1's, and accurate phase measurements are obtained from simple correlation computations. The fringe envelope is also addressed and permits a complete analysis of coherence-limited fringe patterns. Miscalibrations of phase shift and mean wavelength are also considered.

Solving the inverse grating problem by white light interference Fourier scatterometry

“…Applying data analysis methods used in classical white light interferometry, which directly take into account the phase information, could also be beneficial. [30][31][32][33][34][35] de Groot et al…”

Diffraction phase microscopy: retrieving phase contours on living cells with a wavelet-based space-scale analysis

“…To our knowledge, the first attempt to use a wavelet transform as a processing tool with white-light interferometry dates back to 1997. 58 Since then many teams have used this tool with success, in one dimension [59][60][61][62][63][64][65][66][67] as well as in two dimensions. [68][69][70][71][72][73][74][75] More than a simple signal filtering tool, the wavelet transform analysis can also offer the possibility of a direct computation of the phase of the interferometry image, thanks to a wavelet transform ridge detection algorithm.…”

Noise robustness of interferometric surface topography evaluation methods. Correlogram correlation

“…Of course, the basic idea to look for the position of the wave packet in the course of measured correlogram has been touched on earlier, e.g. in [6][7][8], but to our best knowledge it is still ignored in daily applications. This is because it has not been realized until now that this method is the superior to other procedures in precision and stability in a strict mathematical sense.…”

“…Previously, the method was just considered as an additional specific possibility: in this way, the cited works [6], [7] apply it to the special case of transparent film metrology. While [7] employs a complicated window shifting procedure to find the wave package position, [8] already suggests to use the cross-correlation technique. However, the authors of [8] do not consider the idea of a reference correlogram, but use a model wave packet instead.…”

“…While [7] employs a complicated window shifting procedure to find the wave package position, [8] already suggests to use the cross-correlation technique. However, the authors of [8] do not consider the idea of a reference correlogram, but use a model wave packet instead. Since the model wave packet's shape differs from the measured one, the information is lost again -the issuing precision of the method deteriorates.…”