To address the problem that the point cloud on the bottom surface of the measured object cannot be acquired efficiently in 3D laser inspection,a supplementary perspective 3D point cloud scanning method based on the principle of right angle prism refraction is proposed in this paper.The method adopts a right angle prism to refract the bottom view image to the side,compensating for the lack of a bottom detection viewpoint for 3D detection and complements the bottom detection viewpoint.The sealing ring is taken as the defect detection object,and a structured light 3D camera is employed to collect the 3D point cloud.Compared with the direct scanning methods,this approach allows for real time and rapid identification of surface defects with intact sealing rings in a single operation.It particularly simplifies the detection of bottom defects,eliminating the need for specialized gripping devices or complex mechanical structures such as robotic arms,and only the addition of a right angle prism is required.Experimental results demonstrate that the point cloud scanning method with the supplementary perspective using a right angle prism can meet the imaging requirements and effectively detect common defects such as fracture and collapse in sealing rings,achieving a detection accuracy of 100% and fulfilling the requirements of sealing rubber ring defect detection.