Endoscopic 3D defect measurement system for aero-engine blades using digital moiré

The in situ inspection of aero-engine blades is often constrained by confined spaces, where traditional endoscopy methods can only provide two-dimensional images and fail to quantify critical three-dimensional features such as crack depth or edge defect dimensions. To address this challenge, we developed a wide-angle endoscopic three-dimensional (3D) measurement system based on digital moiré. This system integrates a CMOS micro-camera and MicroLED projection module, adopting a parallel optical layout paired with dual wide-angle lenses. Through our proposed multi-frequency spatial domain digital moiré technique, phase extraction and unwrapping are effectively performed. Combined with our designed undistorted phase LUT algorithm, binocular matching is completed in an undistorted domain. Utilizing the stereo model parameters obtained via structured light system calibration method, 3D reconstruction is achieved. Experimental results demonstrate that this system not only realizes device miniaturization but also maintains high-precision 3D reconstruction, offering a novel solution for the online inspection of aero-engine blades.