Reducing ripple error in depth-resolved wavenumber-scanning interferometry using scale-frequency transform

The spectral crosstalk from neighboring peaks introduces phase ripple errors in Depth-Resolved Wavenumber-Scanning Interferometry (DRWSI), due to the sidelope of window functions of Fourier Transform (FT). To address such a problem, an algorithm, Scale-Frequency Transform (SFT), is proposed for data evaluation of DRWSI. The simulations show that the sidelope decreases from −12.2 dB to −25.5 dB after using SFT. The experimental results in four-surface interferometry as well as six-surface interferometry demonstrate that SFT can reduce the phase ripple errors effectively without spoiling the depth resolution of DRWSI. Therefore, SFT minimizes the effect of spectral crosstalk. It is practical to replace FT with SFT in DRWSI.