Real-time high-accuracy 3D facial (micro) expression measurement based on pre-aligned micro-projection arrays

In the field of psychological analysis, the ability to measure high-precision 3D facial (micro) expression sequence data is crucial for understanding emotions and psychological states in specific contexts. However, the real-time high-precision acquisition of continuous 3D facial data still faces challenges due to the limitations of DLP technology in terms of integration, spectral range, cost, and projection rate. This paper introduces a compact, cost-effective, and high-speed infrared pre-aligned micro-projection array (PAMPA) projector to overcome these limitations. The projector employs three independent physical imaging optical paths, enabling time-division control for varied projection patterns, thus avoiding the utilization of a motor as seen in traditional mechanical projectors. The design incorporates an integrated fringe mask, an even and aberration-free light path, high-precision T-slot structural components, and micrometer screw phase alignment technology to address phase alignment issues. It also uses an efficient random phase shift extraction algorithm for phase calculation. Experimental results have verified the success of the proposed method.