Fig. 1. Schematic of a polarization-multiplexing off-axis dual-wavelength digital holographic system, HWP: half-wave plate. M: mirror. BE: beam-expander. Object: a grooved grating. P: polarizer.

Fig. 2. Reconstruction imaging of the polarization-multiplexing dual-wavelength holography, (a) 671 nm hologram, (b) 656 nm hologram, (c) spatial-frequency spectrum of 671 nm hologram, (d) spatial-frequency spectrum of 656 nm hologram, (e) wrapped phase image for 671 nm, (f) wrapped phase image for 656 nm, (g) synthetic phase image, (h) synthetic phase map with phase compensation, and (i) 3D reconstruction map of the height distribution of the object.

Fig. 3. Reconstructed height profile of the grooved grating.

Fig. 4. Grooved depth measured by the profile meter (WYKO NT1100 manufactured by Veeco, USA).