Get up to speed with digital holography with this concise and straightforward introduction to modern techniques and conventions. Building up from the basic principles of optics, this book describes key techniques in digital holography, such as phase-shifting holography, low-coherence holography, diffraction tomographic holography and optical scanning holography, discussing their practical applications, and accompanied by all the theory necessary to understand the underlying principles at work. A further chapter covers advanced techniques for producing computer-generated holograms. Extensive Matlab code is integrated with the text throughout and available for download online, illustrating both theoretical results and practical considerations such as aliasing, zero padding and sampling. Accompanied by end-of-chapter problems and an online solutions manual for instructors, this is an indispensable resource for students, researchers and engineers in the fields of optical image processing and digital holography.

Introduction to Modern Digital Holography: With Matlab

The holographic wavefront printer decodes the wavefront coming from a three-dimensional object from a computer generated hologram displayed on a spatial light modulator. By recording this wavefront as an analog volume hologram this printing method is highly suitable for realistic color 3D imaging. We propose in the paper spatial partitioning of the spatial light modulator to perform mosaic delivery of exposures at primary colors for seamless reconstruction of a white light viewable color hologram. The method is verified for a 3 × 3 color partitioning scheme by a wavefront printer with demagnification of the light beam diffracted from the modulator.

Seamless full color holographic printing method based on spatial partitioning of SLM.

A computer-generated hologram (CGH) is well-known to recon- struct 3-D images faithfully, and several CGH printers are reported. Since those printers can only output a transmission hologram, the large-scale optical system is necessary to reconstruct the full-parallax, full-color image. As a method of a simple reconstruction, it is only necessary to use a volume reflection hologram. However, the making of a volume holo- gram needs to transfer the CGH by means of an optical system. On the other hand, there are printers that output volume type holographic stereo- grams with the full-parallax, full-color image. However, the reconstructed image whose depth is large gets blurred due to the insufficient sampling rays of a 3-D object. The authors propose the volume hologram printer to record the wavefront of a 3-D object. By transferring the CGH that is dis- played on a liquid crystal on silicon, the proposed printer can output the volume hologram. In addition, the large volume hologram can be printed by transferring plural CGH that recorded the partial 3-D object in turn. As a result, the printed volume hologram has been able to reconstruct a mono- chrome 3-D image by white light illumination, and realized the full-parallax image. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). (DOI: 10.1117/1 .OE.51.7.075802)

Volume hologram printer to record the wavefront of three-dimensional objects

Binarization of Fresnel holograms by direct thresholding based on the polarity of the fringe pattern is studied. It is found that if the hologram is binarized (i.e., for black and white hologram pixels) in this manner, only the edges of the object are preserved in the reconstructed image. To alleviate the errors caused by binarization, the use of error diffusion has been routinely employed. However, the reconstructed image using such standard technique is heavily contaminated with random noise. In this paper, we propose a novel noniterative method for generating Fresnel holograms that are suitable for binarization. Our method is capable of preserving good visual quality on the reconstructed images.

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Computer generation of binary Fresnel holography

We propose and demonstrate a volume holographic printing method for dynamic three-dimensional (3D) display with an expanded space-bandwidth product (SBP) using unconventional angular multiplexing techniques. By wavefront encoding of the 3D scene, with the help of computer-generated holography, the object beam is loaded onto a 2D phase spatial light modulator (SLM) with a limited SBP. The printing method then writes a single hologram through the interference of the object beam with a reference beam as a holographic element (hogel) in the volume holographic polymer. In addition, multiple 3D scenes can be recorded and dynamically reconstructed by angular multiplexing in the same hogel location. The SBP can be increased by two orders of magnitude compared to the conventional holographic printing method, showing the potential to realize a dynamic and high-resolution 3D display.

Volume holographic printing using unconventional angular multiplexing for three-dimensional display.

It becomes quite easy to calculate over one hundred million pixels computer-generated hologram of three-dimensional object, even with normal personal computers. On the other hand, it is not so easy to output the calculated result as a hologram that must have micron order resolution for practical three-dimensional display. We have developed a direct fringe printer, which consists of a laser, an X-Y stage and a liquid crystal panel as a spatial light modulator. A fractional part of the entire holographic fringe is displayed on the liquid crystal panel, and the demagnified image of it is recorded on a holographic plate. Then the plate is translated by the x-y stage to write next part of the fringe. We have made some improvements on our previous system. We achieved to print 192 Mega-pixel hologram with 2.8-micron pitch within 40 minutes, three times faster than the previous one. We have also printed 768 Mega-pixel hologram and the full-color rainbow hologram.

Development of direct fringe printer for computer-generated holograms

We have reported that viewing angle of the computer-generated hologram can be expanded with lensless Fourier transform hologram. It, however, requires a laser to illuminate the CGH for reconstruction. In the previous paper, we have proposed that making the second hologram for white-light reconstruction. The reconstructed image from the first hologram is used as the object beam of the second hologram. The second hologram can be either transmission or reflection hologram, which depends on the direction of the reference beam. In this report, we extend this method to make multi-color reflection hologram. First, we calculate the master holograms for each elemental color. Then, the transfer hologram can be made from the master CGH with multimple exposure with either changing wavelength or psuedo-color process. In the experimental result, we obtain multi-color full-parallax computer-generated hologram with 20 degrees of viewing angle and 10 mm × 7.6 mm image size.

Makoto Tachinami

Papers

Development of direct fringe printer for computer-generated holograms

Multicolor reflection hologram made from computer-generated master hologram