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Generation and optical display of a binary-sampled phase-only hologram

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chinese Optics Letters 2016年第1期14卷 12-15页

作者： P. W. M. tsang Y.-t. chow t.-c. Poon J.-P. Liu Department of Electronic Engineering City University of Hong Kong Hong Kong SAR China Bradley Department of Electrical and computer Engineering Virginia Tech Blacksburg VA 24061 USA Department of Photonics Feng Chia University No. 100 Wenhwa Rd. Taichung 407 China

Past research has demonstrated that a phase-only hologram can be obtained by down-sampling the intensity image of the object scene prior to the generation of the hologram. In this Letter, we extend the method to the generation of binary phase-only holograms. A hologram derived with our proposed method is referred to as a binary-sampled phase-only hologram （BSPOH）. Being different from the parent scheme, we have adopted an off- axis configuration in the generation of the BSPOH to avoid the quantization noise, the zeroth-order light, and the conjugate lights. An experimental evaluation reveals that the reconstructed image of the BSPOH is of good quality, and only contains slight amount of noise.

关键词： Bins Holographic displays Lithography

Polarization-Insensitive All-Optical time-Division Demultiplexer constructed with a Nonlinear Loop Interferometer

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光学学报 2003年第S1期23卷 589-590页

作者： t.K. Liang c.S. Wong H.K. tsang c. Shu the chinese University of Hong Kong Department of Electronic Engineering Hong Kong ChinaThe Chinese University of Hong Kong Department of Electronic Engineering Hong Kong ChinaThe Chinese University of Hong Kong Department of Electronic Engineering Hong Kong ChinaThe Chinese University of Hong Kong Department of Electronic Engineering Hong Kong China

A polarization-insensitive 40-Gb/s time-division demultiplexer was demonstrated in a polarization-diversity loop configuration. the power penalty was measured to be 2.3 dB at a bit error rates of 10-9 for 10 Gb/s outp... 详细信息

关键词： OtDM et in Polarization-Insensitive All-Optical time-Division Demultiplexer constructed with a Nonlinear Loop Interferometer UNI were FWHM BERt length of with

Generating a New Higher-Dimensional Ultra-Short Pulse System: Lie-Algebra Valued connection and Hidden Structural Symmetries

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chinese Physics Letters 2012年第2期29卷 29-32页

作者： Hermann t.tchokouansi victor K.Kuetche Abbagari Souleymanou thomas B.Bouetou timoleon c.Kofane National Advanced School of Engineering University of Yaounde IP.O.Box 8390Cameroon Department of Physics Faculty of ScienceUniversity of Yaounde IP.O.Box 812Cameroon Department of Mathematics Faculty of ScienceUniversity of Yaounde IP.O.Box 812Cameroon

We carry out the hidden structural symmetries embedded within a system comprising ultra-short pulses which propagate in optical nonlinear *** upon the Wahlquist Estabrook approach,we construct the Liealgebra valued connections associated to the previous symmetries while deriving their corresponding Lax-pairs,which are particularly useful in soliton *** the wake of previous results,we extend the above prolongation scheme to higher-dimensional systems from which a new (2+ 1)-dimensional ultra-short pulse equation is unveiled along with its inverse scattering formulation,the application of which are straightforward in nonlinear optics where an additional propagating dimension deserves some attention.

关键词： theory nonlinear straight

An enhanced method for fast generation of hologram sub-lines

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chinese Optics Letters 2009年第12期7卷 1092-1096页

作者： P. W. M. tsang J. P. Liu K. W. K. cheung t.-c. Poon Department of Electronic Engineering City University of Hong Kong Tat Chee Avenue Kowloon Hong Kong SAR China Department of Photonics Feng Chia University No. 100 Wenhwa Rd. Seatwen Taichung 40724 China Bradley Department of Electrical and computer Engineering Virginia Tech Blacksburg Virginia 24061 USA

Sub-lines are one-dimensional diffraction patterns representing the light beams emerging from horizontal planes of an object image. Past research has demonstrated that the sub-lines can be encapsulated as a multi-bank filtering process, and implemented with a field programmable gate array （FPGA） device. As the complexity of the filters is high, their length and the number of input pins have to be reduced substantially, hence leading to degradation on the reconstructed images. We propose an enhanced method to overcome the problem by binarizing the filters＇ coefficients, and half-toning the pixel intensities of the object image. Experimental evaluation reveals that our method results in reconstructed images are superior to that obtained with the parent method.

关键词： Diffraction Field programmable gate arrays (FPGA) Holographic interferometry

Review on theory and applications of wavefront recording plane framework in generation and processing of digital holograms

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chinese Optics Letters 2013年第1期11卷 18-24页

作者： P. W. M. tsang t.-c. Poon Department of Electronic Engineering City University of Hong Kong Bradley Department of Electrical and computer Engineering

the wavefront recording plane （WRP）, subsequently generalized to be known as the virtual diffraction plane （VDP）, is a recent concept that has been successfully deployed in fast generation and processing of digital holograms. In brief, the WRP and its extension, the VDP, is a hypothetical plane that is located between the hologram and the object scene, and which is at close proximity to the latter. As such, the fringe patterns on the hypothetical plane are carrying the holistic information of the hologram, as well as the local optical properties of the object scene. this important property enables a hologram to be processed with classical image processing techniques that are normally unsuitable for handling holographic information. In this paper we shall review a number of works, that have been developed based on the framework of the WRP and the VDP.

关键词： Review on theory and applications of wavefront recording plane framework in generation and processing of digital holograms

Enhancement on the generation of sampled phase-only holograms

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chinese Optics Letters 2015年第6期13卷 27-30页

作者： P.W.M.tsang Y.t.chow t.-c.Poon Department of Electronic Engineering City University of Hong Kong Hong KongSpecial Administrative Region (SAR) Bradley Department of Electrical and computer Engineering

Past research has demonstrated that if the intensity image of an object is uniformly down-sampled and converted into a Fresnel hologram, the phase component alone will be sufficient to reconstruct the source image. However, due to down-sampling, the edge and line patterns are degraded heavily. In this Letter, we propose an enhance- ment on the parent method by incorporating an adaptive down-sampling lattice. A hologram generated with our proposed method, which is referred to as the edge-enhanced sampled phase-only hologram, preserves favorable visual quality on both the shaded regions as well as the edge patterns of the object image.

关键词： Lithography Signal sampling

Enhanced method for the generation of binary Fresnel holograms based on grid-cross downsampling

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chinese Optics Letters 2011年第12期9卷 15-19页

作者： W.K.cheung Peter tsang t.c.Poon 周常河 Department of Electronic Engineering City University of Hong KongTat Chee AvenueKowloon Bradley Department of Electrical and computer Engineering Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences

Past research has demonstrated that digital Fresnel holograms can be binarized in a non-iterative manner by downsampling the source image with a grid lattice prior to the hologram generation process. the reconstructed image of a hologram that is binarized with this approach is superior in quality compared with that obtained with direct thresholding, half-toning, and error diffusion. Despite the success, the downsampling mechanism results in a prominent texture of regularly spaced voids in the shaded regions. to alleviate this problem, an enhanced non-iterative method for the generation of binary Fresnel holograms is presented. Our method is based on a multi-direction line-sampling formed by a combined grid and cross lattice, which is capable of preserving a more solid texture in the shaded regions and enhancing the visual quality of the reconstructed image. computer simulations and optical reconstructions are shown to demonstrate the effectiveness of our proposed technique.

关键词： computer simulation Lithography textures

Data-embedded-error-diffusion hologram(Invited Paper)

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chinese Optics Letters 2014年第6期12卷 76-79页

作者： P. W. M. tsang t.-c. Poon Department of Electronic Engineering City University of Hong KongHong Kong SAR China Bradley Department of Electrical and computer Engineering Virginia TechBlacksburg VA 24061 USA Shanghai Institute of Optics and Fine Mechanics Chinese Academy of SciencesShanghai 201800 China

this paper describes a method for converting a complex Fresnel hologram into a phase-only hologram that can be embedded with large amount of data. Briefly, each row of pixels in the hologram is scanned sequentially in a left-to-right direction. the magnitude of each visited pixel is set to a constant, and its phase is embedded with the data. Subsequently, the error is diffused to the neighborhood pixels. the phase hologram realized with such means, which is referred to as the data-embedded-error-diffusion （DEED） hologram, is capable of preserving high fidelity on the content of the hologram and the embedded data.

关键词： Data-embedded-error-diffusion hologram

Fast numerical generation and hybrid encryption of a computer-generated Fresnel holographic video sequence

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chinese Optics Letters 2013年第2期11卷 27-31页

作者： Peter tsang K.W.-K. cheung t.-c. Poon Department of Electronic Engineering City University of Hong KongTat Chee AvenueKowloon Bradley Department of Electrical and computer Engineering Virginia TechUSA Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences

Research demonstrates that a Fresnel hologram can be generated and simultaneously encrypted numerically based on a secret symmetric key formed by the maximal length sequence （M-sequence）. the method can be directly extended to encrypt a video holographic clip in a frame-by-frame manner. However, given the limited combination of signals in the family of M-sequence, hacking the secret key through trial and error can be time consuming but not difficult. In this letter, we propose a method that is difficult to crack with brute force for enerypting a holographic video sequence. An M-sequence is first randomly assigned to enerypt each frame of the holographic video signal. Subsequently, the index of the selected M-sequence, which is necessary to decrypt the hologram~ is encrypted with the RSA algorithm before transmitting to the receiving end. At the receiving end, the decoder is provided with a private key to recover the index for each frame, and the corresDonding M-se（mence is used to decrvDt the encoded hologram.

关键词： Access control computer generated holography cryptography Personal computing Video recording