Fig. 1. Schematic of digital holography.

Fig. 2. Schematic of hybrid phase retrieval algorithm

Fig. 3. Simulation verification of two methods. (a) Object; (b) in-line hologram; (c) off-axis hologram.

Fig. 4. Reconstructed results of in-line hologram. (a) Amplitude image; (b) phase image.

Fig. 5. Reconstructed results of off-axis hologram. (a) Amplitude image; (b) phase image.

Fig. 6. Mean squared errors at each iteration

Fig. 7. Reconstructed results obtained by the in-line and off-axis hybrid digital holography. (a) Amplitude image; (b) phase image

Fig. 8. Schematic of the experimental setup

Fig. 9. Experimental results of resolution target. (a) In-line hologram; (b) off-axis hologram; (c) reconstructed by the traditional phase retrieval with the in-line hologram; (d) reconstructed by the constrained optimization algorithm with the off-axis hologram; (e) reconstructed by the in-line and off-axis hybrid digital holography

Fig. 10. Experimental results of the wing of a dragonfly. (a) Image obtained by microscopy; (b) amplitude reconstructed image of the in-line hologram; (c) phase reconstructed image of the in-line hologram; (d) amplitude reconstructed image of the off-axis hologram; (e) phase reconstructed image of the off-axis hologram; (f) amplitude reconstructed image of the in-line and off-axis hybrid digital holography; (g) phase reconstructed image of the in-line and off-axis hybrid digital holography

Fig. 11. Comparison of experimental results of dragonfly wing tips. (a) Phase reconstructed image of the two-step phase-shifting digital holography; (b) phase reconstructed image of the in-line and off-axis hybrid digital holography