Phase of white light and its compatibility to the optical path

The phase of monochromatic light directly relates to the optical path difference (OPD), but finding this connection for spectrally broadband is challenging. Due a missing concept compatibility between randomly fluctuating fields and OPD, demanding scanning only proven way highly accurate OPD measurement in white light. Here, we use self-coherence function (SCF) spatially incoherent reveal white-light OPD. Our method uses an associated field assigned SCF mimic intensity oscillation correlation pattern. allows restoring cumulative integrated into across all spectral constituents. essential quantitative microscopy, which available even light, its processing beyond quasi-monochromatic approach still lacking. Improper assessment may result loss accuracy, as demonstrate theoretically experimentally. Deploying our coherence-controlled holographic measured with strongly asymmetric spectrum (bandwidth 150 nm), achieving accuracy better than 5 nm measuring depth range 2 µm.