Fig. 1. Measurement standard of rectangular grating groove depth. (a) Definitonof traditional "W/3" guideline; (b) application of "W/3" guideline in rectangular grating; (c) influence of batwing effect on judgement of W

Fig. 2. Coherence signal characteristics of sampling points at different locations. (a) Middle position; (b) step edge

Fig. 3. Coherence peak position distribution of different rectangular gratings. (a) Different groove depths; (b) different linewidths

Fig. 4. Flow chart of proposed algorithm

Fig. 5. Edge positioning of rectangular grating. (a) Simulation interferogram; (b) coherence peak information; (c) binarization result

Fig. 6. Experimental system. (a) Optical path diagram; (b) photo of white light microscopic interference system

Fig. 7. Measurement process of rectangular grating sample. (a), (b) Sample measurement area; (c), (d) interferogram; (e), (f) mask matrix; (g), (h) three-dimensional morphology restoration results

Fig. 8. Measurement repeatability data. (a) Sample A; (b) sample B

Fig. 9. Effect of sample placement angle. (a) Tilt illustration diagram; (b) experimental data

Fig. 10. Effect of interference fringe. (a) Fringe number; (b) fringe direction