Optimal spatial bandwidth capacity in multiplexed off-axis holography for rapid quantitative phase reconstruction and visualization

Is multiplexed off-axis holography for quantitative phase imaging more spatial bandwidth-efficient than on-axis holography? [Invited]

“…Digital multiplexing of off-axis holograms refers to the multiplexing operation performed not by the optical setup, but rather implemented in the computer. It is used mainly for speeding up hologram reconstruction, by applying simple arithmetic operations in the hologram domain to compress multiple wavefronts into a single hologram, from which the SFD of all wavefronts can be retrieved with a single 2-D DFT [31][32][33][34][35].…”

“…However, the concept of sum is further generalized from the one described in Eq. ( 8), to a complex-weighted sum; since in digital multiplexing, the off-axis phase 𝜑 𝑜 (𝑥, 𝑦) is typically identical for all holograms, the desired shift in the SFD is usually achieved by multiplying each hologram by a different complex exponent in the hologram domain prior to summation [32,34,35], as can be seen in Eq. ( 10):…”

“…Either way, as long as the aim of the digital multiplexing is speeding up reconstruction, the multiplexed hologram can contain complex values. The most efficient digital multiplexing architecture, recently suggested by us, includes multiplexing sixteen wavefronts into a single complex hologram [35], but can only be applied to DC-free holograms. The most efficient architecture that does not mandate DC-free holograms was suggested by Sha et al and allows multiplexing of eight wavefronts into a single complex hologram [34].…”

“…6PH represents the optimal bandwidth consumption when the DC terms are present. We have later also suggested multiplexing eight holograms (8PH) [35], by utilizing the space occupied by the DC terms. This architecture is illustrated in Fig.…”

Fast phase reconstruction in off-axis digital holography with zero-order term suppression

“…Off-axis digital holography (DH) has garnered a great deal of interest from the scientific community over the past decade because it can provide a quantitative phase imaging in one shot, thus allowing for acquisition at the camera's frame rate [1][2][3][4][5]. In off-axis DH, the Fourier transform method is usually employed to implement phase reconstruction because the zero-order and conjugate-order (+1st and -1st diffraction orders) terms generated by the recorded hologram can be separated in the spectral domain.…”