Fig. 1. Structure of white light interferometry measurement system employing a stepper motor for vertical scanning

Fig. 2. Flowchart for implementing optimal hyperparameter selection using a search algorithm

Fig. 3. Principle of the morphology recovery algorithm based on region-directed up-sampling

Fig. 4. Flow chart of morphology measurement algorithm

Fig. 5. Simulated vertical scanning data. (a) Simulated scanning position; (b) scanning interval error; (c) white light interferometry image

Fig. 6. Comparison between the fitting reconstruction signal and the ideal signal

Fig. 7. Comparison of step morphology reconstructed by different algorithms. (a) Centroid method; (b) proposed algorithm

Fig. 8. Comparison of residual distribution of reconstructed surfaces under non-equidistant sampling. (a) Centroid method; (b) proposed algorithm

Fig. 9. White light interferometry image of step plates collected in the experiment

Fig. 10. Scanning position and scanning interval error of stepper motor. (a) Scanning position; (b) scanning interval error

Fig. 11. Comparison of reconstructed morphology and cross-section of standard steps by various algorithms. (a) Centroid method;

Fig. 12. Solution error. (a) Positioning error of the interpolated FFT envelope algorithm; (b) comparison of vertical profile curves solved by various algorithms