Q-Spectrum and its application for the characterization of mid-spatial frequencies es on polished surfaces

The current paper reports on the application of the Q-Spectrum for the characterization of mid-spatial frequencies on polished surfaces (plane, spherical, and aspheres). The Q-Spectrum based on the Forbes Qmn polynomials for freeforms allows, when taken to large radial and azimuthal orders, a robust and accurate representation of mid-spatial surface spectral footprints that otherwise cannot be faithfully identified with other methods. Evaluation of experimental data with the Q-Spectrum as well as a comparison with other methods is shown. (C) 2018 Optical Society of America