LAUSR

A route of spatial modulation-assisted scanning white-light interferometry with the inhibition of background noises and light source fluctuations for the topography measurement of micro-/nano-structure surface was explored in this letter. The spatial modulation frequency was introduced by tilting the sample at a small angle to separate the noise signals and interference signals in the spatial frequency domain. A band-pass filter and a normalization processing were also applied with the purpose of signal-to-noise-ratio improvement and contrast enhancement. The frequency domain analysis was then enrolled in the elimination of $2\pi $ ambiguity for the surface recovery with high-presicion. Both the theoretical analysis and the experiment results reveal the validity of spatial modulation-assisted scanning white-light interferometry and its potentials in high-fidelity measurement of smooth surfaces regardless of external disturbances.