Effective improvement of depth resolution and reduction of ripple error in depth-resolved wavenumber-scanning interferometry

•A complex number least squares algorithm was used in DRWSI.•The depth-resolution is dramatically improved.•The phase ripple errors are reduced.

The bottleneck problem hindering the development of Depth-Resolved Wavenumber-Scanning Interferometry (DRWSI) is a limited depth resolution due to a finite range of the laser wavenumber scanning. A robust Complex Number Least Squares Algorithm (CNLSA) is proposed in the present study to take full advantage of phase and amplitude information over the entire range of frequencies, and the algorithm performs much better than any window function. Experimental results as well as simulations show that the phase ripple error is reduced and the depth resolution is significantly refined. A CNLSA is likely to become practical and suitable for DRWSI applications.