Research into digital holography (DH), the process of electronically recording and numerically reconstructing an optical field, has made tremendous strides in recent years. To highlight breakthroughs in this area, the editors of the Optical Society's (OSA (http://www.osa.org)) journal Applied Optics (http://www.opticsinfobase.org/ao/home.cfm) have teamed with the editors of the journal Chinese Optics Letters (http://www.opticsinfobase.org/col/home.cfm) to publish a special Focus Issue on Digital Holography and 3-D Imaging (http://www.opticsinfobase.org/ao/issue.cfm?volume=50&issue=34). The issue was organized and edited by Guest Editors Ting-Chung Poon from the Bradley Department of Electrical and Computer engineering at Virginia Tech in Blacksburg, Va.; Changhe Zhou from the Shanghai Institute of Optics and Fine Mechanics at the Chinese Academy of Sciences in Shanghai, China; Toyohiko Yatagai from the Center for Optical Research and Education at Utsunomiya University in Tochigi, Japan; Byoungho Lee from the School of Electrical Engineering at Seoul National University in Seoul, Korea; and Hongchen Zhai from the Institute of Optics at Nankai University in Tianjin, China.
The focus issue features a selection of topics that were presented at OSA's DH and 3-D Imaging topical meeting (http://www.osa.org/Meetings/Archives/2011/DH-2011-Archive.pdf) in Tokyo in May. Topical meeting presentations covered the fundamentals and applications of holographic and digital methods in optical science and technology including 3-D display, optical remote sensing, optical image processing, and holographic microscopy.
In addition to increasingly popular 3-D movies and displays, DH and 3-D imaging are widely known for their biomedical imaging applications, as digital holographic microscopy provides a non-invasive method for visualizing and quantifying biological specimens. DH is also used in structural analysis, fluid flow measurement, and 3-D image processing.
Key Findings and Select Papers
The following papers are some of the highlights of the Applied Optics and Chinese Optics Letters Focus Issue on Digital Holography and 3-D Imaging. See Volume 50, Issue 34 for the Applied Optics papers, accessible online at http://www.opticsinfobase.org/ao/issue.cfm. The Chinese Optics Letters papers will be accessible online at http://www.opticsinfobase.org/col/home.cfm. In this paper, the authors discuss a novel technique called digitized holography. The wave field of real objects is captured in a wide area by synthetic digital holography, which is then incorporated in virtual 3-D scenes. The end result of the reconstructed 3-D images can be digitally editable, achievable and transmittable.
Paper: "Digitized holography: modern holography for 3D imaging of virtual and real objects (http://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-50-34-H278)," Applied Optics, Vol. 50, Issue 34, pp. H278-H284 (2011).
Compressing sensing is a technique to recover a sparse signal in the most efficient possible way. The technique has been used widely in signal and image processing as well as in computational mathematics. Compressive sensing applied to the reconstruction of holograms is a recent novel trend in digital holography and is called compressive holography. This article is a tutorial for general readers to understand compressive holography.
Paper: "Sampling and processing for compressive holography (http://www.opticsinfobase.org/ao/abstract.cfm?uri=ao-50-34-H75)," Applied Optics, Vol. 50, Issue 34, pp. H75-H86 (2011).
This article gives an overview of many 3-D displays, from stereoscopic to holographic displays, including historical perspectives. It is useful for not only researchers of 3-D display but also for researchers in optical imaging.
Paper: "Three-dimensional display technologies of recent interest: principles, status, and issues (http://www.opticsinfobase.org/ao/abstract.cfm?uri=ao-50-34-H87)," Applied Optics, Vol. 50, Issue 34, pp. H87-H115 (2011).Platforms of tomographic imaging using digital holography typically have relatively complex optical and mechanical setups. The present authors have recently developed lens-free optical tomography based on on-axis digital holography, which has relatively simple on-chip architectures and can be particularly useful for lab-on-a-chip applications with submicron-resolution. The article reviews this recently developed technique.
Paper: "Partially coherent lensfree tomographic microscopy (http://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-50-34-H253)," Applied Optics, Vol. 50, Issue 34 pp. H253-H264 (2011)Conventional multiplex holograms are composed of a series of long thin individual holograms, which inevitably cause the reconstructed images overlaid with a picket-fence structure. The authors discuss a disk-type multiple hologram which is free from the picket-fence effect. In addition, the disk-type multiplex hologram has the advantage of commercial mass production owing to the utilization of the well-developed CD technology.
Paper: "Image design for normal viewing image-plane disk-type multiplex hologram (http://www.col.org.cn/abstract.aspx?id=COL201109120003-03)," Chinese Optics Letters, Vol. 9, Issue 12, pp. 120003 (2011). Vector quantization (VQ) is a classical compression technique for signal and image processing. However, the use of VQ has not been very successful in compressing holograms until the demonstration by the present authors , showing state-of-the-art experimental results with a compression ratio over 1600 times and still with the preservation of acceptable visual quality on the reconstructed holographic images
Paper: "Low-bit-rate computer-generated color Fresnel holography with compression ratio of over 1600 times using vector quantization (http://www.opticsinfobase.org/ao/abstract.cfm?uri=ao-50-34-H42)," Applied Optics, Vol. 50, Issue 34, pp. H42-H49 (2011).In this paper, the authors propose an original approach for measuring the derivatives of the in-plane and out-of-plane displacement components by digital holographic interferometry. The measurements can be carried out simultaneously with the use of an RGB CCD camera and two laser sources at two different wavelengths
Paper: "Simultaneous measurement of in-plane and out-of-plane displacement derivatives using dual-wavelength digital holographic interferometry (http://www.opticsinfobase.org/ao/abstract.cfm?uri=ao-50-34-H16)," Applied Optics, Vol. 50, Issue 34, pp. H16-H21 (2011).