Digital holographic profilometry with symmetric structured illumination

Digital Holographic Microscopy (DHM) is an interferometric technique widely used for surface profiling. It is valued for its high phase measurement accuracy. However, DHM relies on plane-wave illumination, which limits resolution. Structured illumination (SI) can overcome this limitation, improving resolution. DHM reconstructs amplitude and phase images digitally; however, the phase is confined to a 2π. Recent research has explored multi-beam illumination and proposes Digital Holographic Profilometry (DHP) as a potential solution. In this work, the Structured Illumination Digital Holographic Profilometry (SI-DHP) system, which is a combination of DHP and SI techniques, will be proposed. The developed system, equipped with a DMD modulator, generates illumination with sinusoidal fringes for SI. A special algorithm, combining the longitudinal scanning function of DHP with the SI algorithm, was developed for shape reconstruction. The article presents simulation results demonstrating high longitudinal resolution and an extended measurement range.