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Browsing by Author "Kim, Taegeun"

Now showing 1 - 10 of 10
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    Autofocusing in optical scanning holography
    Kim, Taegeun; Poon, Ting-Chung (Optical Society of America, 2009-12-01)
    We present autofocusing in optical scanning holography (OSH) with experimental results. We first record the complex hologram of an object using OSH and then create the Fresnel zone plate (FZP) that codes the object constant within the depth range of the object using Gaussian low-pass filtering. We subsequently synthesize a real-only spectrum hologram in which its phase term contains information about a distance parameter. Finally, we extract the distance parameter from the real-only spectrum hologram using fringe-adjusted filtering and the Wigner distribution. Using the extracted distance parameter, we reconstruct a three-dimensional image of the object from the complex hologram using digital convolution, which bypasses the conventional blind convolution to reconstruct a hologram. To the best of our knowledge, this is the first report with experimental results that autofocusing in OSH is possible without any searching algorithm or tracking process. (C) 2009 Optical Society of America
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    Horizontal-parallax-only electronic holography
    Poon, Ting-Chung; Akin, T.; Indebetouw, Guy J.; Kim, Taegeun (Optical Society of America, 2005-04-01)
    The principle of optical scanning holography (OSH) is proposed to acquire horizontal-parallax-only (HPO) holographic information electronically. We first briefly summarize the results of OSH and then discuss how HPO-electronic holographic information can be acquired using OSH. Finally we provide simulations to illustrate and clarify the proposed idea. Although many ideas of HPO-holography have been proposed and studied, to the best of our knowledge, this is the first proposed electronic technique to acquire HPO-holographic information. (C) 2005 Optical Society of America.
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    Multiple-image encryption by compressive holography
    Di, Hong; Zheng, Kangfeng; Zhang, Xin; Lam, Edmund Y.; Kim, Taegeun; Kim, You Seok; Poon, Ting-Chung; Zhou, C. H. (Optical Society of America, 2012-03-01)
    We present multiple-image encryption (MIE) based on compressive holography. In the encryption, a holographic technique is employed to record multiple images simultaneously to form a hologram. The two-dimensional Fourier data of the hologram are then compressed by nonuniform sampling, which gives rise to compressive encryption. Decryption of individual images is cast into a minimization problem. The minimization retains the sparsity of recovered images in the wavelet basis. Meanwhile, total variation regularization is used to preserve edges in the reconstruction. Experiments have been conducted using holograms acquired by optical scanning holography as an example. Computer simulations of multiple images are subsequently demonstrated to illustrate the feasibility of the MIE scheme. (C) 2012 Optical Society of America
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    Optical Image Recognition Of Three-Dimensional Objects
    Poon, Ting-Chung; Kim, Taegeun (Optical Society of America, 1999-09-01)
    A three-dimensional (3-D) optical image-recognition technique is proposed and studied. The proposed technique is based on two-pupil optical heterodyne scanning and is capable of performing 3-D image recognition. A hologram of the 3-D reference object is first created and then is used to modulate spatially one of the pupils of the optical system; the other pupil is a point source. A 3-D target object to be recognized is then scanned in two dimensions by optical beams modulated by the two pupils. The result of the two-dimensional scan pattern effectively displays the correlation of the holographic information of the 3-D reference object and that of the 3-D target object. A strong correlation peak results if the two pieces of the holographic information are matched. We analyze the proposed technique and thereby lay a theoretical foundation for optical implementations of the idea. Finally, computer simulations are performed to verify the proposed idea. (C) 1999 Optical Society of America.
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    Optical Scanning Cryptography For Secure Wireless Transmission
    Poon, Ting-Chung; Kim, Taegeun; Doh, K. (Optical Society of America, 2003-09-01)
    We propose a method for secure wireless transmission of encrypted information. By use of an encryption key, an image or document is optically encrypted by optical heterodyne scanning and hence encryption is performed on the fly. We call this technique optical scanning cryptography. The output of the heterodyne encrypted signal is at radio frequency and can be directly sent through an antenna to a secure site for digital storage to be prepared for decryption. In the secure site, an identical optical scanning system to that used for encryption is used, together with a decryption key, to generate an electrical signal. The electrical signal is then processed and sent to a computer to be used for decryption. Utilizing the stored information received from the encryption stage and the electrical information from the secure site, a digital decryption unit performs a decryption algorithm. If the encryption key and the decryption key are matched, the decryption unit will decrypt the image or document faithfully. The overall cryptosystem can perform the incoherent optical processing counterpart of the well-known coherent double-random phase-encoding technique. We present computer simulations of the idea. (C) 2003 Optical Society of America.
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    Optical Scanning Holography for 3-D Imaging of Fluorescent Objects in Turbid Media
    Kim, Taegeun (Virginia Tech, 1997-12-09)
    A holographic recording method using an optical heterodyne 2-D scanning technique for 3-D imaging of fluorescent objects in turbid media is described and experimentally demonstrated. For the first time, 3-D imaging of fluorescentobjects in turbid media by a holographic method is achieved, and the diffused photon rejecting process through a heterodyne technique is analyzed. We also propose and realize a multiplexing and a digital decoding method for removing twin-image noise in optical scanning holography. The holographic method studied can be applied to 3-D biomedical imaging of fluorescent objects in turbid media as well as diffusely reflecting objects.
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    Optical Three-Dimensional Image Matching Using Holographic Information
    Kim, Taegeun (Virginia Tech, 2000-07-19)
    We present a three-dimensional (3-D) optical image matching technique and location extraction techniques of matched 3-D objects for optical pattern recognition. We first describe the 3-D matching technique based on two-pupil optical heterodyne scanning. A hologram of the 3-D reference object is first created and then represented as one pupil function with the other pupil function being a delta function. The superposition of each beam modulated by the two pupils generates a scanning beam pattern. This beam pattern scans the 3-D target object to be recognized. The output of the scanning system gives out the 2-D correlation of the hologram of the reference object and that of the target object. When the 3-D image of the target object is matched with that of the reference object, the output of the system generates a strong correlation peak. This theory of 3-D holographic matching is analyzed in terms of two-pupil optical scanning. Computer simulation and optical experiment results are presented to reinforce the developed theory. The second part of the research concerns the extraction of the location of a 3-D image matched object. The proposed system basically performs a correlation of the hologram of a 3-D reference object and that of a 3-D target object, and hence 3-D matching is possible. However, the system does not give out the depth location of matched 3-D target objects directly because the correlation of holograms is a 2-D correlation and hence not 3-D shift invariant. We propose two methods to extract the location of matched 3-D objects directly from the correlation output of the system. One method is to use the optical system that focuses the output correlation pattern along depth and arrives at the 3-D location at the focused location. However, this technique has a drawback in that only the location of 3-D targets that are farther away from the 3-D reference object can be extracted. Thus, in this research, we propose another method in which the extraction of a location for a matched 3-D object is possible without the aforementioned drawback. This method applies the Wigner distribution to the power fringe-adjusted filtered correlation output to extract the 3-D location of a matched object. We analyze the proposed method and present computer simulation and optical experiment results.
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    Solving inverse problems for optical scanning holography using an adaptively iterative shrinkage-thresholding algorithm
    Zhao, F. J.; Qu, X. C.; Zhang, Xin; Poon, Ting-Chung; Kim, Taegeun; Kim, Y. S.; Liang, J. M. (Optical Society of America, 2012-03-01)
    Optical scanning holography (OSH) records a three-dimensional object into a two-dimensional hologram through two-dimensional optical scanning. The recovery of sectional images from the hologram, termed as an inverse problem, has been previously implemented by conventional methods as well as the use of l(2) norm. However, conventional methods require time consuming processing of section by section without eliminating the defocus noise and the l(2) norm method often suffers from the drawback of over-smoothing. Moreover, these methods require the whole hologram data (real and imaginary parts) to eliminate the twin image noise, whose computation complexity and the sophisticated post-processing are far from desirable. To handle these difficulties, an adaptively iterative shrinkage-thresholding (AIST) algorithm, characterized by fast computation and adaptive iteration, is proposed in this paper. Using only a half hologram data, the proposed method obtained satisfied on-axis reconstruction free of twin image noise. The experiments of multi-planar reconstruction and improvement of depth of focus further validate the feasibility and flexibility of our proposed AIST algorithm. (c) 2012 Optical Society of America
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    Speckle-free digital holographic recording of a diffusely reflecting object
    Kim, Y. S.; Kim, Taegeun; Woo, S. S.; Kang, H.; Poon, Ting-Chung; Zhou, Changhe (Optical Society of America, 2013-04-01)
    We demonstrate holographic recording without speckle noise using the digital holographic technique called optical scanning holography (OSH). First, we record a complex hologram of a diffusely reflecting (DR) object using OSH. The incoherent mode of OSH makes it possible to record the complex hologram without speckle noise. Second, we convert the complex hologram to an off-axis real hologram digitally and finally we reconstruct the real hologram using an amplitude-only spatial light modulator (SLM) without twin-image noise and speckle noise. To the best of our knowledge, this is the first time demonstrating digital holographic recording of a DR object without speckle noise. (C)2013 Optical Society of America
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    Three-dimensional display of a horizontal-parallax-only hologram
    Kim, Y. S.; Kim, Taegeun; Poon, Ting-Chung; Kim, J. T. (Optical Society of America, 2011-03-01)
    We propose a three-dimensional (3D) holographic display by converting an optically recorded complex full-parallax (FP) hologram to an off-axis horizontal-parallax-only (HPO) hologram. First, we record the complex FP hologram of an object using optical scanning holography. We then convert the complex FP hologram to an off-axis HPO hologram through fringe-matched Gaussian low-pass filtering and with the introduction of an off-axis reference. Finally, we reconstruct the off-axis HPO hologram optically using an amplitude-only spatial light modulator. Until now, only computer-generated HPO holograms have been displayed optically. To the best of our knowledge, this is the first demonstration of a 3D display of an optically recorded HPO hologram. (C) 2011 Optical Society of America