Multi-incidence digital holographic profilometry with high axial resolution and enlarged measurement range

In this work, multi-incident digital holographic profilometry for microscale measurements is presented. This technique assembles the set of object fields from captured holograms for generation of the longitudinal scanning function (LSF). Numerical propagation is used for refocusing, and thus, the LSF can be determined at any given plane along the optical axis. The LSF takes maximum value for in focus object points, which are used to obtain full-field height distribution of the sample. This principle is the base of proposed measurement technique. Three capturing holograms strategies, which give control over the shape of the LSF, unambiguous measurement range, axial resolution, and noise immunity, are discussed. The conclusions of this work are supported by numerical and experimental results.