Defect and deformation comprehensive measurement method based on dual-wavelength speckles

Composite materials are widely used in aviation, aerospace, and other fields. Poor service conditions, insufficient stiffness or strength of materials and other problems can cause deformation and defects of composite materials, affecting their service life and safety. Optical detection methods can measure composite materials' surface deformation and internal defects separately. However, there is a lack of comprehensive measurement methods for defects and deformation in these optical detection methods. It causes the problems of complicated detection steps, inefficiency in engineering, and is not conducive to in-depth analysis of the detection results. This paper proposes a comprehensive defect and deformation measurement method based on dual-wavelength speckles, which is beneficial for solving the above problems. The measurement system includes four parts: the control module, the speckle binocular vision module for 3D morphology measurement, the speckle interferometry module for internal defect detection, and the data processing module. Firstly, the system should perform trinocular calibration. Then, the control module controls the speckle interferometry module and the speckle binocular vision module to emit lasers with different wavelengths. Speckles of different colors and sizes are formed on the surface of the composite material specimen. The cameras corresponding to the two modules are controlled to capture speckle images. The data processing module processes the speckle images separately to obtain defect and morphology information. It then uses the information fusion algorithm to integrate the 2D defect and 3D morphology information to complete the measurement. Composite material specimens with internal defects of different sizes and shapes were measured. Finally, the comprehensive detection of both internal defects and 3D morphology of composite materials was realized with this method.