Phase Unwrapping for 3D Surface Topography Measurement

Phase unwrapping serves as a fundamental technique in 3D surface topography measurement. During the 3D measurement process, accurate surface topography information requires precise phase measurement of the object's surface. However, due to limitations in measurement equipment and environmental interference, the obtained phase information is often incomplete. Consequently, phase unwrapping becomes necessary to reconstruct complete phase data. To prevent error propagation effects during phase unwrapping, Saldner and Huntlye introduced temporal phase unwrapping methodology. This approach leverages temporal phase variations to perform unwrapping, effectively avoiding error propagation commonly found in traditional phase unwrapping methods. The MATLAB simulation implementation typically involves generating synthetic phase sequences using functions like peaks or custom 3D surface models, applying wrapping operations with modulo-2π calculations, and executing temporal unwrapping algorithms through frame-by-phase-frame processing. Furthermore, to validate the effectiveness of temporal phase unwrapping, we conducted simulations using MATLAB. The simulation results demonstrate that temporal phase unwrapping can effectively reconstruct surface phase information, thereby enhancing both accuracy and stability in 3D topography measurements. Key implementation aspects include phase gradient calculation using diff functions, temporal coherence checks, and cumulative phase integration algorithms that maintain consistency across sequential frames.