Surface contouring of reflective and diffuse samples using dual-angle digital holographic shear interferometry

In this work, a grating-based dual-angle digital holographic shear interferometry system is presented for generating synthetic wavelengths and extending the measurable height range. A geometric-phase (GP) grating and mirror configuration generates laterally sheared wavefronts at multiple shear orientations, while a polarization camera enables simultaneous phase-shifted intensity acquisition. Measurements are performed at two illumination angles, and the reconstructed complex wavefields are combined to obtain a synthetic phase distribution whose sensitivity is determined by the angular separation between the two measurements. The system was experimentally evaluated using standard step-height artifacts and surface features on both reflective and diffuse samples. Step-height measurements demonstrated the dependence of measurement performance on the selected synthetic wavelength. An analytical uncertainty analysis identified the illumination angle as a significant contributor to the overall measurement uncertainty, emphasizing the importance of system calibration using a standard artifact. Temporal repeatability was also evaluated through repeated measurements. The results demonstrate the capability of grating-based dual-angle digital holographic shear interferometry for quantitative three-dimensional surface reconstruction while maintaining a compact common-path configuration.