Multisurface-decoupling defect inspection of transparent elements based on binocular transmissive structured light

Localizing and distinguishing defects on the front and back surfaces of transparent elements is critical for process optimization. We propose a multisurface-decoupling defect inspection method based on binocular transmissive structured light. The transmissive configuration provides high sensitivity and a large dynamic range. A high-precision virtual ray-tracing model exploits the geometric constraints between surface-defect coordinates and the dual cameras to achieve robust front-back decoupling. Experiments on plane-parallel plates and plano-concave lenses verify the method, including a lens with a central thickness of 2.15 mm. Simulations show that the minimum separable thickness for a plane-parallel plate is 0.46 mm.