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Conference on Three-Dimensional Imaging, Visualization, and Display

作者： Zhang Fen Cheng Hong Zhang Quanbing Wei Sui Anhui Univ Minist Educ Key Lab Intelligent Comp & Signal Proc Hefei 230039 Peoples R China Anhui Univ Key Lab Modern Imaging & Displaying Technol Hefei 230039 Peoples R China

ISBN: (纸本)9781628416114

Phase is an inherent characteristic of any wave field. Statistics show that greater than 25% of the information is encoded in the amplitude term and 75% of the information is in the phase term. The technique of phase retrieval means acquire phase by computation using magnitude measurements and provides data information for holography display, 3D field reconstruction, X-ray crystallography, diffraction imaging, astronomical imaging and many other applications. Mathematically, solving phase retrieval problem is an inverse problem taking the physical and computation constraints. Some recent algorithms use the principle of compressive sensing, such as PhaseLift, PhaseCut and compressive phase retrieval etc. they formulate phase retrieval problems as one of finding the rank-one solution to a system of linear matrix equations and make the overall algorithm a convex program over nxn matrices. However, by "lifting" a vector problem to a matrix one, these methods lead to a much higher computational cost as a result. Furthermore, they only use intensity measurements but few physical constraints. In the paper, a new algorithm is proposed that combines above convex optimization methods with a well known iterative fourier transform algorithm (IFTA). The IFTA iterates between the object domain and spectral domain to reinforce the physical information and reaches convergence quickly which has been proved in many applications such as compute-generated-hologram (CGH). Herein the output phase of the IFTA is treated as the initial guess of convex optimization methods, and then the reconstructed phase is numerically computed by using modified TFOCS. Simulation results show that the combined algorithm increases the likelihood of successful recovery as well as improves the precision of solution.

关键词： iterative fourier transform algorithm GS convex optimization phase retrieval PhaseLift

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Modified iterative algorithm for the design of wide-diffraction angle diffraction optical element

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OPTICAL ENGINEERING 2015年第9期54卷 093106-093106页

作者： Lv, Xiangbo Song, Qiang Li, Denggao Qiao, Ya Lu, Yuan Zhu, Jing Huang, Huijie Chinese Acad Sci Shanghai Inst Opt & Fine Mech Lab Informat Opt & Optoelect Technol Shanghai 201800 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China Inst Elect Engn Hefei 230037 Peoples R China

A fast and effective algorithm for designing the diffraction optical element (DOE) with a wide-diffraction angle is presented. DOE had been widely used in many fields in recent years, but there are finite methods which can design DOE with wide-diffraction angle quickly occupying a small quantity of computing resource. By the use of a nonparaxial scalar diffraction equation as the light transmission operator, a modified iterative algorithm is proposed. To verify our algorithm, the checkerboard image, binary image, and gray-scale image are numerically simulated, respectively. The simulation results show that the final variance between the preset image and final pattern is very small, the value is generally lower than 10-5, and the natural images even have a final variance less than 10-12. At the same time, the diffraction efficiency has been significantly increased to be larger than 90%, which indicates that the design method is effective and practical. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)

关键词： iterative fourier transform algorithm diffraction optical element nonparaxial diffraction wide-diffraction angle

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Optical implementation of iterative fourier transform algorithm using spatial light modulator

Optical implementation of iterative Fourier transform algori...

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Conference on Photonic Devices and algorithms for Computing VIII

作者： Hahn, Joonku Kim, Hwi Lim, Yongjun Lee, Jihyun Lee, Byoungho Seoul Natl Univ Sch Elect Engn Seoul 151744 South Korea

ISBN: (纸本)0819463892

We propose an optical implementation of iterative fourier transform algorithm using a spatial light modulator and phase-shifting digital holography technique. It is shown that the optically implemented iterative fourier transform system can improve quality of target diffraction images in real time by the same way the numerical iterative fourier transform algorithm does in the numerical simulation. In the proposed implementation, the wave front of diffraction field is directly measured by the phase shifting digital holography technique and the phase modulation of light field is performed by a phase-type spatial light modulator. The feasibility and more general applicability of the proposed implementation of the iterative fourier transform algorithm for digital holography techniques are discussed.

关键词： optical implementation iterative fourier transform algorithm spatial light modulator digital holography

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Spatial frequency and fractal complexity in single-to-triple beam holograms

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JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS 2010年第1期12卷 105-109页

作者： Scarlat, E. I. Mihailescu, M. Sobetkii, A. Univ Politehn Bucuresti Dept Phys Bucharest 060042 Romania OPTICOAT Ltd Bucharest Romania

A new method of assessing the efficiency and uniformity of particular application of a single-to-triple beam conversion for obtaining structured beam configurations is investigated. Conversion efficiency and signal uniformity in the object space are related to the fractal properties in the DOE spatial frequencies as revealed by the multifractal spectrum (MFS), and the associated complex microstructure measured by the Lempel-Ziv complexity (LZC). By directly evaluating MFC and LZC in the DOE plane one can have a complementary instrument when designing phase holograms. These quantities are furnishing valuable technological information for the manufacturing stage: higher values for MFS require greater imprinting finesse, precision, and control, while higher values for LZC need more gray levels, more complex algorithms and more processing resources. In the exploitable range for optical tweezers applications there were revealed correlations of the pairs MFS <-> efficiency and LZC <-> uniformity. Experimental implementation qualitatively confirms the computational simulations.

关键词： Diffractive optical element iterative fourier transform algorithm Multifractal spectrum Lempel-Ziv complexity

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Symmetrical iterative fourier-transform algorithm using both phase and amplitude freedoms

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OPTICS COMMUNICATIONS 2006年第2期267卷 347-355页

作者： Liu, J. S. Caley, A. J. Taghizadeh, M. R. Heriot Watt Univ Sch Engn & Phys Sci Phys Edinburgh EH14 4AS Midlothian Scotland

A modified Gerchberg-Saxton algorithm, which we call symmetrical iterative fourier transform algorithm, is presented and employed to a series of super-Gaussian beam shaping problems and arbitrary beam shaping problems. The main features of this algorithm include (1) using an amplitude-symmetric function of the failed result about the fourier-domain constraint;(2) using both phase and amplitude freedoms in the iteration process, i.e. the noise produced outside the signal window by each iteration is kept. A formula is given to determine a critical constant in the search for the amplitude-symmetric function. The new method results in highly efficient solutions with highly precise beam profiles in the signal window for all the test problems. (c) 2006 Elsevier B.V. All rights reserved.

关键词： Gerchberg-Saxton algorithm iterative fourier transform algorithm diffractive optics beam shaping pulse shaping phase retrieval image reconstruction

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iterative fourier transform algorithm with adaptive regularization parameter distribution for optimal design of diffractive optical elements

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JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS 2004年第6A期43卷 L702-L705页

作者： Kim, H Lee, B Seoul Natl Univ Sch Elect Engn Seoul 151744 South Korea

Generally, uniformity can be improved at the cost of a low diffraction efficiency in the design of diffractive optical elements by the conventional iterative fourier transform algorithm. This trade-off is a fundamental limitation of the conventional iterative fourier transform algorithm. However in this letter, a novel iterative fourier transform algorithm with adaptive regularization parameter distribution for alleviating the trade-off between uniformity and diffraction efficiency and for improving uniformity is devised on the basis of the theoretical analysis of the trade-off property in the conventional iterative fourier transform algorithm scheme. The validity of the proposed algorithm is proved by numerical experiments.

关键词： diffractive optical element iterative fourier transform algorithm regularization parameter uniformity

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Generation of phase-shift patterns in the optical far field and its applications

Generation of phase-shift patterns in the optical far field ...

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Conference on Holography and Diffractive Optics III

作者： Hsu, Wei-Feng Chen, Yu-Weng Su, Yuan-Hong Natl Taipei Univ Technol Dept Electropt Engn 1 Sec 3Chung Hsiao E RdNTUT Box 4623 Taipei 10608 Taiwan Natl Tsing Hua Univ EE Dept Inst Photon Technol Hsinchu 30013 Taiwan

ISBN: (纸本)9780819470072

We introduce and compare two methods to produce the phase-shift patterns, which are widely generated in the near-field lithography, in the optical far field. The key component of the two methods is a phase-only diffractive optical element, a similar function found in the maskless lithography. The technique to produce a smaller feature size was a major improvement beyond the diffraction limit.

关键词： phase-shift lithography diffraction limit phase-only diffractive optical elements iterative fourier transform algorithm blazed grating array simulated annealing algorithm full-width at half averaged intensity

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Generation of fractal speckle using computer-generated holograms and its application to speckle correlometry

Generation of fractal speckle using computer-generated holog...

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2008 International Conference on Optical Instruments and Technology

作者： Hideki Funamizu Masayuki Kagawa Yukihiro Ishii Department of Applied Physics Tokyo University of Science

When a diffuser is illuminated by the coherent light with intensity distributions obeying a negative power law, speckle fields with fractal properties are *** a random field is called fractal *** speckles have extremely long spatial correlation functions of the intensity distributions in comparison with ordinary *** implies that fractal speckles may extend measurement ranges in various metrological applications based on the spatial correlation of *** report the generation of fractal speckles using computergenerated holograms based on the method of stationary phase and the iterative fourier transform algorithm, and its application to speckle correlometry is discussed.

关键词： Fractal Speckle Fractal speckles The method of stationary phase iterative fourier transform algorithm

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Performances comparison of amplitude object and phase object recording in LiNbO₃ crystal

Performances comparison of amplitude object and phase object...

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Conference on Optics and Photonics for Information Processing

作者： Lin, Ching Yang Wu, Ming Chan Liu, Jung-Ping Yau, Hon-Fai Natl Cent Univ Dept Opt & Photon Jhongli 32001 Taoyuan Taiwan Feng Chia Univ Dept Photon Wenhwa Rd Taichung 40724 Taiwan

ISBN: (纸本)9780819468437

We proposed a novel optical geometry for holographic data storage in which a phase input pattern was involved. The input phase pattern was derived from an amplitude pattern by iterative fourier transform algorithm. Two important parameters of reconstructed images, diffraction efficiency and image quality, were discussed and measured. Our geometry exhibited uniform holographic recording as well as uniform erasing. Moreover, the loss of light due to absorption in the input pattern was minimized. The little light loss also ensured a higher diffraction efficiency of the reconstructed image.

关键词： holographic storage phase hologram lithium niobate photorefractive iterative fourier transform algorithm

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Realisation of a holographic micro laser scalpel using a digital micromirror device

Realisation of a holographic micro laser scalpel using a dig...

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Conference on Optical Measurement Systems for Industrial Inspection V

作者： Zwick, Susanne Warber, Michael Haist, Tobias Osten, Wolfgang Univ Stuttgart Inst Tech Opt D-70569 Stuttgart Germany

ISBN: (纸本)9780819467584

Modern spatial light modulators (SLM) enable the generation of more or less arbitrary light fields in three dimensions. Such light fields can be used for different future applications in the field of biomedical optics. One example is the processing/cutting of biological material on a microscopic scale. By displaying computer generated holograms by suitable SLMs it is possible to ablate complex structures into three-dimensional objects without scanning with very high accuracy on a microscopic scale. To effectively cut biological materials by light, pulsed ultraviolet light is preferable. We will present a combined setup of a holographic laser scalpel using a digital micromirror device (DMD) and holographic optical tweezers using a liquid crystal display (LCD). The setup enables to move and cut or process micro-scaled objects like biological cells or tissue in three dimensions with high accuracy and without any mechanical movements just by changing the hologram displayed by the SLMs. We will show that holograms can be used to compensate aberrations implemented by the DMD or other optical components of the setup. Also we can generate arbitrary light fields like stripes, circles or arbitrary curves. Additionally we will present results for the fast optimization of holograms for the system. In particular we will show results obtained by implementing iterative fourier transform based algorithms on a standard consumer graphics board (Nvidia 8800GLX). By this approach we are able to compute more than 360 complex 2D FFTs (512 x 512 pixels) per second with floating point precision.

关键词： computer generated holograms spatial light modulator laser scalpel digital mirror device iterative fourier transform algorithm graphics processing unit holographic optical tweezers

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