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We present an efficient approach for fast phase reconstruction in simultaneous dual-wavelength off-axis digital holography. We demonstrate that one can directly extract the quantitative unwrapped phase information through only one application of Fourier-based operations after applying a square operation on a dual-wavelength off-axis hologram. Compared to the state-of-the-art dual-wavelength reconstruction approaches, our approach sufficiently simplifies the reconstructed procedure without any special requirements, and yields high-speed reconstruction. Both numerical simulations and experiments are demonstrated to establish the validity of the proposed approach.

Incorporating the advantages of the differential synthetic-wavelength and the additive synthetic-wavelength, we improve the linear programming algorithm for the phase reconstruction of dual-wavelength digital holography. Under the designated two dimensional boundary conditions, the improved linear programming algorithm is employed to search the optimal integer pair for the two aforementioned wavelengths. The convergence is determined by the square of height difference, in which the heights are obtained with the two aforementioned wavelengths, respectively. In comparison with other state-of-the-art approaches, our approach is straightforward to create phase unwrapping with similar or even better reconstruction quality. Both the numerical and experimental results were conducted to prove the feasibility and effectiveness of our approach.

In this study, three efficient algorithms are proposed for fast phase retrieval in slightly off-axis digital holography using spectrum cropping, spatial multiplexing, and complex encoding. In the first algorithm, the real spectral order of the subtracted hologram is filtered and cropped, and the number of pixels is decreased in the subsequent retrieval operations. In the second algorithm, two sequential subtracted holograms are digitally phase shifted and spatial multiplexed into one synthetic hologram, and thus only one inverse Fourier transformation is then required. In the third algorithm, two sequential subtracted holograms are encoded separately into the real part and the imaginary part of a complex hologram. Two cross-correlations can be used to reconstruct the phase, thereby improving the utilization of the spectrum. The three new algorithms speed up our previously proposed retrieval method with the assistance of specimen-free holograms. Our experiments demonstrated the validity and improved time requirements of the proposed methods.

An interferometric phase microscopy (IPM) is proposed using slightly-off-axis reflective point diffraction interferometry for quantitative phase imaging. A retro-reflector consisting two mirrors is used to generate an angle between the object beam and reference beam, and a 45° tilted polarizing beam splitter is used to split the horizontal and vertical components of the both beams. Two carrier interferograms with π/2 phase-shift can be acquired in one shot, and the phase distribution of a thin specimen can be retrieved using a fast reconstruction method. The new IPM without loss in the utilization of the input-plane field of view combines the real time and optimizing detector bandwidth measurement benefit associated with slightly-off-axis method, high stability associated with common path geometry, and simplicity in terms of procedure and setup. Experiments are carried out on both static and dynamic specimens to demonstrate the validity and stability of the proposed method.

Divided-aperture (DA) microscopy is an imaging method that, in addition, improves the anti-scattering capability. The present state-of-the-art imaging methods have the drawbacks of requirement of scanning or low spatial resolution. In this paper, we propose a DA digital holographic microscopy (DADHM) to enable single shot quantitative phase imaging, which, to our knowledge, is the first-of-its-kind. The proposed system is built using a Linnik-type interferometric module associated with the DA technique. In this method, interestingly, an element tilt is not required to produce an off-axis angle between the sample and reference beams because of the employment of DA. Some analyses and experiments were conducted to validate the efficiency of the proposed method, and the results indicate that a high anti-scattering capability with a mean error of 2.42 nm were achieved by the proposed method.

A common-path interferometer using the modified Michelson system with a reflective grating is proposed for quantitative phase imaging. The frequency spectrum of the object beam is split into two beams using a beam splitter. One beam is diffracted into +1, 0, and −1 orders by the reflective grating to act as an object beam, and the other beam is low-filtered and diffracted by a pinhole mirror to act as a reference beam. Three phase-shifted interferograms can be simultaneously captured using the proposed interferometer, and the specimen phase can then be reconstructed from the three interferograms. Experiments are carried out to prove the precision, real-time ability, and stability of the proposed method.