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.

We present a digital holography using high dynamic range (HDR) imaging to improve quality of the reconstructed image of digital holography. The technique extends the dynamic range of the digitally recorded hologram using multiple holograms recorded with different exposures. We numerically and experimentally demonstrated the technique based on an off-axis digital holography system. In the numerical simulation and experiment, the quality of the reconstructed images by the proposed technique is higher than that by the conventional digital holography without HDR imaging.

The authors present high-speed motion pictures of phase-image obtained by digital holography. To obtain only the complex amplitudes of dynamically moving objects free from unwanted images such as non-diffraction wave and the conjugate image in digital holography, parallel phase-shifting interferometry was applied. High-speed motion picture of phase image of the dynamic change of air induced by focused femtosecond light pulse was demonstrated at the rate of 262,500 fps. Also, motion pictures of phase image of high-speed air breakdown induced by the spark discharge between two electrodes at the rate of one-mega frames-per second have been achieved. This speed is the fastest not only phase-shifting digital holography but also all of digital holography.

We propose an algorithm for extracting the image of an object from the reconstructed image in the in-line digital holography using two holograms reported by Y. Zhang. In the proposed algorithm the non-diffraction wave can be analytically calculated by using the intensity of the reference wave and be removed from the reconstructed image. We confirmed the validity of the proposed algorithm by numerical results. In comparison with the algorithm reported by Zhang, it was found that the proposed algorithm reduced the errors down to 1/5 and 1/3 in amplitude and phase by the simulation, respectively when the ratio of the amplitude of the reference wave to that of the object wave was 4. Thus, if have been confirmed that the digital holography employing the proposed algorithm have be suitable for high-precision three-dimensional image capturing and measurement.

This paper presents an overview of the potential of free space optical technology in information security, encryption, and authentication. Optical waveform posses many degrees of freedom such as amplitude, phase, polarization, spectral content, and multiplexing which can be combined in different ways to make the information encoding more secure. This paper reviews optical techniques for encryption and security of two-dimensional and three-dimensional data. Interferometric methods are used to record and retrieve data by either optical or digital holography for security applications. Digital holograms are widely used in recording and processing three dimensional data, and are attractive for securing three dimensional data. Also, we review optical authentication techniques applied to ID tags with visible and near infrared imaging. A variety of images and signatures, including biometrics, random codes, and primary images can be combined in an optical ID tag for security and authentication.

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.

Describes various techniques to implement optical dynamic interconnections using the photorefractive effect. Two categories of optical dynamic interconnections are discussed. One is based on free-space optics and the other on guided optics. These include a real-time volume hologram, a mutually pumped phase conjugator, a spatial light modulator, a waveguide, and a spatial soliton.