Fast and precise multi-angle interferometry for efficient 3D surface profiling

We introduce a novel, to the best of our knowledge, low-complexity multi-angle interferometry (MAI) method that resolves the critical trade-off between high precision, achieved when using the longitudinal scan function (LSF), and low computational load, achieved when using conventional MAI. Our method eliminates the need for computationally expensive LSF-evaluation optical-propagation calculations, significantly reduces complexity, and enables real-time surface topography measurement. Reliability is ensured by using phase differences to calculate the surface height and by selecting the beam-pair height with the maximum pairwise LSF (max-pLSF) at each pixel. Our method incorporates three key features for superior accuracy: surface-height-induced tilt-component compensation, precision-enhancing feedback, and continuous max-pLSF monitoring to prevent error propagation (e.g., at step edges). The experimental results confirmed high precision over ±20 μm, achieving a flat-surface standard deviation within 150 nm. By integrating high accuracy with low computational cost, this technique is ideally suited for practical high-speed, high-precision surface profiling.