Twin-image problem in digital holography—a survey (Invited Paper)

Abstract

Zero-order and twin images are a serious obstacle in achieving a high-quality output in in-line digital holography (DH). They decrease the useful bandwidth of the off-axis DH. Over the years the twin image removal problem was approached both by instrumental and numerical means. The paper provides an extended survey of the proposed solutions with their pros and cons as a guide for further advance in this field. Processing of a single spatial carrier fringe pattern involves spatial filtering in the frequency domain, spatial phase-shifting (PS) or wavelet transform. A point source digital holographic microscopy (DHM), introduction of calibration measurements or various modifications of PS technique are instrumental solutions to the twin image problem for in-line DH. Numerical solutions to the same problem include iterative and non-iterative approaches, diffraction-based and inverse problem solutions, reconstruction of purely real or phase objects and of complex objects, reconstruction of plane and volume objects. Elimination only of the zero-order image relies on non-linear filtering or additional calibration measurements.

Digital plasmonic holography

“…If the phase of the object wave were known completely, the reconstruction would yield a single point-source without the extraneous fringes. However, much effort has gone into reducing the effects of the twin image 47 . Indeed, various options would be directly and naturally applicable to plasmonic DHM, including iterative techniques 48 and recording multiple holograms at two or more distances 49 .…”

“…While these initial results demonstrate a proof-of-concept for plasmonic DHM, various improvements are anticipated. For example, several techniques should be directly applicable toward reduction of twin-image interference for higher-quality plasmonic image reconstruction 47 . Additionally, fast real-time imaging should also be possible using the fluorescent screens since only a small portion (i.e., a single line) of a single camera frame is necessary to extract the holograms and reconstruct the objects.…”

3D Capture and 3D Contents Generation for Holographic Imaging

“…Feature recognition based on digital holography has been proposed [15]. A lot of efforts were dedicated to instrumental or software solutions of the twin image problem [16].…”

Fast reconstruction of multiple off-axis holograms based on a combination of complex encoding and digital spatial multiplexing

“…According to the relative orientations between the object beam and the reference beam in a holographic recording system, DHs are often divided into two categories: on-axis and off-axis. The former is capable of effectively utilizing the spatial frequency bandwidth of image sensors and thus can capture finer sample spatial details, but it suffers from the disturbance of the zeroorder autocorrelation and the conjugate image, which need to be eliminated by using phase-shifting techniques or other time-consuming elimination algorithms [22][23][24][25][26] . In off-axis DHs, the autocorrelation and the conjugate items are separated from the required image item in the spatial frequency domain and thus can be eliminated simply by digital spatial filtering [27][28][29][30] , although the off-axis geometry will result in an extra demand for the bandwidth of imaging sensors.…”