Surface profiling using sequential sampling and inverse methods. Part II: Implementation and experimental results

Sequential sampling with inverse calculation is demonstrated to provide a practical and reliable method for profiling surfaces, independent of rigid-body motions. Examples are given where various arrangements of displacement sensors can provide single-sided, double-sided, and parallel profilling. Double-sided measurements also give specimen thickness, and parallel measurements give surface twist. In common with other inverse calculation methods, there is a tradeoff between achievable spatial resolution and sensitivity to measurement noise. Such sensitivity, which typically doubles the measurement noise in the computed profiles, can be minimized by appropriate choice of sensor configuration, measurement method, and use of regularization. Practical guidelines for all these features are given, together with example experimental results for four typical sensor configurations.