High-precision 3D optical profilometry of non-cooperative targets by time-domain dual-comb coherent averaging

A challenge in industrial non-contact surface mapping applications is to resolve the competing requirements of high measurement precision and sufficient large working distance. In this letter, we introduce a three-dimensional (3D) surface profilometry system with micrometer-level precision at a 100-mm working distance for non-cooperative targets by employing an electro-optic dual-comb system in conjunction with time-domain coherent averaging. The detection capability of weak diffuse reflective signals is enhanced by 15 dB via time-domain coherent averaging for 1000 times, which ensures minimum outliers in complex 3D-structure mapping applications. By further leveraging an environment-insensitive optical path, we have demonstrated the use 3D optical profilometry at the megapixel scale for various non-cooperative workpieces, validating the wide applicability of this approach.