Fig. 1. The scheme of the broadband light interferometric microscopy

Fig. 2. Modulation map of the interference pattern with threshold labeled
R_a is the region where the modulation value is greater than the set threshold, and R_b is the region where the modulation value is less than the set threshold

Fig. 3. The unwrapping method of rhombus algorithm
A starting point(point 1)is taken as the seed pixel, and phase unwrapping is carried out in a rhombus path with this pixel as center

Fig. 4. Relationship between two adjacent regions to be stitched
The expansion phase matrices R₁ and R₂ corresponding to position Ⅰ and Ⅱ, R₁₂ is the overlapped region of the matrices R₁ and R₂

Fig. 5. Simulation of phase unwrapping and stitching
(a): Peaks function; (b), (c): Interference images at position Ⅰ and Ⅱ

Fig. 6. 3D structure of the peaks surface reconstructed by three different algorithms
(a): Least-Square method; (b): Branch-Cut method; (c): Proposed algorithm

Fig. 7. Micro-nano structure measurement experiment
(a): The gray scale image of the measured sample;(b)—(d): Modulation map at different positions

Fig. 8. Contrast of three methods for phase unwrapping
(a): Reshaped topography by Least-Square method; (b): Reshaped topography by Branch-Cut method; (c): Reshaped topography by Proposed algorithm; (d), (e) and (f): The height curve in the Cross-section profile indicated by red line (y=500) in (a), (b) and (c)