Improved modulation-based structured illumination microscopic 3D measurement with complementary binary fringes

Structured illumination microscopy for optical sectioning is widely used for micro- and nanoscale surface topography measurement, but the conventional phase-shifting approach requires multiple image acquisitions, leading to a trade-off between measurement speed and accuracy. To overcome this limitation, we propose a complementary binary fringe difference method for structured illumination microscopy to obtain optical sectioning at each layer. Theoretical derivation and simulation experiments demonstrate that the modulation signal obtained through complementary binary fringe difference exhibits an axial intensity profile approximating a symmetric Bessel function curve. This enables the determination of depth positions corresponding to peak intensities via Gaussian function fitting, thereby realizing surface shape measurement. Experimental results on a 1.8 µm step-height sample demonstrated the effectiveness of the proposed method, achieving a root-mean-square error of 29 nm.