Integrated polarization imaging system and multi-source fusion framework for thermally induced micro-instability non-destructive detection and characterization

The manufacturing of high-performance aerospace components with complex geometries for extreme operating conditions poses significant challenges that conventional processing techniques cannot adequately address. Selective laser melting (SLM) has emerged as a pivotal advanced manufacturing technology; however, its application in high-end domains is substantially hindered by thermally induced micro-instabilities (TIMIs) resulting from process variations. To overcome the difficulties in achieving high-precision and robust detection and characterization of TIMIs on highly reflective metal surfaces, this study introduces an integrated telecentric polarization imaging system combined with a multi-source information fusion and super-resolution reconstruction framework. By effectively isolating environmental stray light through multi-angle polarization analysis and integrating polarization-intensity multimodal data with deep learning-based super-resolution reconstruction, the proposed method significantly enhances the signal-to-noise ratio for micrometer-scale defects against highly reflective backgrounds. Experimental results demonstrate that the modulation transfer function of the developed imaging system exceeds 0.3 at the Nyquist frequency of 100 lp/mm, meeting the requirements for high-fidelity imaging of microscopic features. After processing with the MMIF-SR algorithm, the information entropy of the detected images increased by 2.441, and the standard deviation rose by 15.589, leading to a marked improvement in image contrast. These enhancements allow for clear visualization of defect contours and micro-features, thereby substantially improving TIMIs detection in complex environments. This work provides an effective technical solution for TIMIs detection and characterization, which are critical to the in-service performance of high-performance SLM components. It holds significant value for advancing the manufacturing engineering of major aerospace equipment.