Nanoscale morphology imaging for arbitrary surfaces by optical coherence tomography

The imaging of nanoscale morphology using optical methods on arbitrary surfaces poses challenges, particularly in the presence of large axial distances and irregular shapes. In this work, we introduce a novel nano-resolution imaging method along the longitudinal direction, utilizing optical coherence tomography (OCT) to measure arbitrary surface morphology comprehensively. Based on the sparsity of the primary profile, our approach allows the adjustment of parameters such as the asymmetric penalty function phi, the regularization parameters alpha i and a high-pass filter to accommodate the micro-structure of any arbitrary surface. Remarkably, our method achieves an exceptional spatial resolution of 3.04 nm. The technique has been validated by observing the surface morphology of spherical and aspherical lenses with nanometer resolution in the longitudinal direction. With the ability to detect impurities and scratches with a height of tens of nanometers, this method can be used to study the fine structure of complex surfaces. This makes it an ideal choice for experimental requirements demanding high-resolution imaging and a broad en-face perspective.