Digital holography is a technique that permits digital capture of
holograms and subsequent processing on a digital computer. This
paper reviews various applications of this technique. The presented
applications cover three-dimensional (3-D) imaging as well as several
associated problems. For the case of 3-D imaging, optical and
digital methods to reconstruct and visualize the recorded objects
are described. In addition, techniques to compress and encrypt 3-D
information in the form of digital holograms are presented. Lastly,
3-D pattern recognition applications of digital holography are discussed.
The described techniques constitute a comprehensive approach
to 3-D imaging and processing.

Three-Dimensional Imaging and ProcessingUsing Computational Holographic Imaging

A review of snapshot multidimensional optical imaging: Measuring photon tags in parallel

Optical holography for recording three-dimensional (3-D) scenes can be traced back to the early sixties. Since then, the art of holography has been applied in many areas, primarily as a tool for 3-D imaging, processing, and display. Extension of optical holography to other disciplines, such as optical computing and encryption, has been explored, but the scope of development is relatively limited. However, with the rapid advancements in electronics, computing, and material science technologies, most of the optical processes can be substituted with numerical or digital hardware means, thus leading to the emergence of digital holography. A typical digital holography framework can be encapsulated into three major stages, namely the input, processing, and output stages. The input and output stages are gatekeepers connecting the optical and digital worlds, without which the study on digital holography could only be restricted to theoretical and numerical analysis. In the past few decades, numerous research works have been conducted on these two important areas. In this paper, we shall provide a review on the recent development in these two important areas of digital holography. Selected pieces of important and popular works on the acquisition and display of digital holograms will be reported.

Review on the State-of-the-Art Technologies for Acquisition and Display of Digital Holograms

We propose a low-cost, compact, and field-portable 3D printed holographic microscope for automated cell identification based on a common path shearing interferometer setup. Once a hologram is captured from the portable setup, a 3D reconstructed height profile of the cell is created. We extract several morphological cell features from the reconstructed 3D height profiles, including mean physical cell thickness, coefficient of variation, optical volume (OV) of the cell, projected area of the cell (PA), ratio of PA to OV, cell thickness kurtosis, cell thickness skewness, and the dry mass of the cell for identification using the random forest (RF) classifier. The 3D printed prototype can serve as a low-cost alternative for the developing world, where access to laboratory facilities for disease diagnosis are limited. Additionally, a cell phone sensor is used to capture the digital holograms. This enables the user to send the acquired holograms over the internet to a computational device located remotely for cellular identification and classification (analysis). The 3D printed system presented in this paper can be used as a low-cost, stable, and field-portable digital holographic microscope as well as an automated cell identification system. To the best of our knowledge, this is the first research paper presenting automatic cell identification using a low-cost 3D printed digital holographic microscopy setup based on common path shearing interferometry.

Compact and field-portable 3D printed shearing digital holographic microscope for automated cell identification.

Digital holography provides a method of the 3-D recording and numerical reconstruction by a simple optical system and a computer. Quantitative measurement and numerical refocusing are major characteristics. So far, many physical parameters such as amplitude, phase, polarization, fluorescence, and spectra can be obtained independently. Recently, multimodal imaging that can obtain simultaneously two or more physical parameters by combining digital holographic microscope and other optical microscopes such as a fluorescence optical microscope and a Raman scattering microscope has emerged. In this review, physical parametric imaging techniques based on digital holography are presented and then these techniques are enhanced to develop multimodal imaging based on digital holography.

Multimodal Imaging Based on Digital Holography

Parallel phase-shifting digital holography using a phase-mode spatial light modulator (SLM) is proposed. The phase-mode SLM implements spatial distribution of phase retardation required in the parallel phase-shifting digital holography. This SLM can also compensate dynamically the phase distortion caused by optical elements such as beam splitters, lenses, and air fluctuation. Experimental demonstration using a static object is presented.

Parallel phase-shifting digital holography with adaptive function using phase-mode spatial light modulator

Parallel phase-shifting digital holography (PPSDH) method can record dynamic three-dimensional events with higher
spatial resolution than that of off-axis digital holography. In PPSDH, all amount of phase retardations are included in a
multiplexed hologram and can be optically implemented by using a phase-mode spatial light modulator (SLM) located in
the reference beam. The SLM can also compensate optical aberration caused by lenses, beam splitters, and air fluctuation
as in adaptive optics. In this presentation, we review our experimental results using stationary two-dimensional object
using a liquid-crystal on Silicon (LCOS) SLM.

Miao Lin

Papers

Parallel phase-shifting digital holography with adaptive function using phase-mode spatial light modulator

Parallel phase-shifting digital holography using LCOS-SLM