Real-time three-dimensional object reconstruction of digital holograms using liquid crystal spatial light modulators

We propose and demonstrate a three-dimensional object reconstruction technique that uses complete amplitude and phase information of a phase-shifting digital hologram by cascading liquid crystal spatial light modulators with a nearly full-range complex modulation. The cascaded liquid crystal module is performed by operating both in amplitude-mostly and phase-mostly modulation modes. The amplitude-mostly modulation is applied by minimizing the phase variation, whereas the phase-mostly mode is achieved by minimizing the amplitude variation during the voltage-driven period. The transfer characteristic of the cascaded liquid crystal module is analyzed by the Jones matrix method to yield the suitable polarization states for realizing full-range complex modulation. It is well known that a digital hologram can store both amplitude phase information of an optical electric field and can reconstruct the original three-dimensional object by numerical calculation. This work demonstrates that it is possible to reconstruct optically three-dimensional objects using complete amplitude and phase information of the optical field calculated from the phase-shifted digital holograms. The use of both amplitude and phase information enable us to reconstruct optically three-dimensional objects with fair image quality by selecting the orientation of polarization and the modulation conditions of the cascaded liquid crystal module. Both analytical and experimental results are presented and discussed.