Dynamic 3D profiling of microscale surface using a MEMS mirror laser differential confocal microscope

Several advanced techniques have been used for 3D micro-surface profiling, such as white light interferometry, confocal microscopy, and atomic force microscopy. However, a major technological limitation shared among these methods is the difficulty of imaging dynamic samples in real-time at high resolution. Specifically, profiling rapidly changing or moving surfaces at nanoscale 3D spatial resolution remains a challenging task. We demonstrate here a high-speed MEMS mirror-based laser differential confocal microscope for dynamic 3D micro-surface profiling. The MEMS mirror enables 2D scanning of 1200 × 650 pixels with a 140 × 90 μm field of view at 80 frames per second. Using laser differential confocal detection, the system achieves 25 nm axial resolution. The objective-space telecentric laser projection results in uniform axial response across the field of view, simplifying data acquisition and processing. These capabilities enable real-time 3D micro/nano scale profiling of dynamically changing surfaces at 80 frames per second without requiring motion stages. The system's substantial increase in imaging throughput enables, for the first time, real-time 3D profiling of dynamic microscale surface topographies at nanometer-level axial resolutions. The high-speed 3D profiling enabled by this system provides new insights for process development and quality control in precision micro/nano fabrication.