Spatiotemporal heterodyne multiplexing in digital holography for realizing broad recordable bandwidth

To realize high-capacity holographic multiplexing, we propose an off-axis frequency-modulated continuous-wave digital holography (FMCW-DH) that utilizes both temporal and spatial frequencies as the multiplexable bandwidth. The temporal and spatial carrier frequencies for the multiplexed wavefronts are achieved by the frequency-modulated continuous-wave technique of the light source and the off-axis configuration of digital holography, respectively. The effectiveness of the proposed technique is demonstrated by multiplexing the multiple holograms generated by illuminating two objects at two wavelengths. Also, the phase distribution maps reconstructed from the recorded complex wavefronts were used to measure the surface profile of the known step height by using the two-wavelength method.