Computation of 3D weld pool surface from the slope field and point tracking of laser beams

A novel computation method of the 3D weld pool surface from specular reflection of laser beams is presented in this paper. The mathematical model for the three-dimensional surface measurement technique has been developed. The structured pattern of a laser is projected on the weld pool in a molten state and the reflection observed using a CCD camera. These reflected patterns can be tracked using image processing techniques including optical flow and moving point tracking. A simulation model has been developed implementing these techniques. The movement of the reflected laser during the welding process is indicative of the change in state of the weld pool. The surface slope field is calculated from the law of reflection and is used to compute the 3D surface of the weld pool. The measurement technique is tested on objects with a priori knowledge of geometry having a specular surface to test the effectiveness of the measurement technique.