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Xifeng Xiao

Bio: Xifeng Xiao is an academic researcher from New Mexico State University. The author has contributed to research in topics: Physical optics & Beam (structure). The author has an hindex of 14, co-authored 72 publications receiving 795 citations.


Papers
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Journal ArticleDOI
TL;DR: A numerical wave optics approach for simulating a partial spatially coherent beam by application of a sequence of random phase screens to an initial beam field and the summation of the intensity results after propagation is presented.
Abstract: A numerical wave optics approach for simulating a partial spatially coherent beam is presented. The approach involves the application of a sequence of random phase screens to an initial beam field and the summation of the intensity results after propagation. The relationship between the screen parameters and the spatial coherence function for the beam is developed and the approach is verified by comparing results with analytic formulations for a Gaussian Schell-model beam. The approach can be used for modeling applications such as free space optical laser links that utilize partially coherent beams.

102 citations

Journal ArticleDOI
TL;DR: In this article, a phase-only liquid-crystal spatial light modulator (SLM) was proposed to control both the phase and amplitude using a single SLM, thereby making the amplitude filters unnecessary.
Abstract: A technique is presented to produce any desired partially coherent Schell-model source using a single phase-only liquid-crystal spatial light modulator (SLM). Existing methods use SLMs in combination with amplitude filters to manipulate the phase and amplitude of an initially coherent source. The technique presented here controls both the phase and amplitude using a single SLM, thereby making the amplitude filters unnecessary. This simplifies the optical setup and significantly increases the utility and flexibility of the resulting system. The analytical development of the technique is presented and discussed. To validate the proposed approach, experimental results of three partially coherent Schell-model sources are presented and analyzed. A brief discussion of possible applications is provided in closing.

84 citations

Journal ArticleDOI
TL;DR: An approach is described for creating random complex screens to be used in computer simulations of arbitrary Schell-model beams with a prescribed far-field intensity distribution and the evolution in the free-space propagation from the source plane to the far zone is illustrated.
Abstract: An approach is described for creating random complex screens to be used in computer simulations of arbitrary Schell-model beams with a prescribed far-field intensity distribution. Simulation examples including beam profiles with reflection symmetry and rotational symmetry, flat-top, and pyramidal shapes are presented to verify the proposed approach. A more general scenario with a nonsymmetric far-field beam shape is illustrated to demonstrate the evolution in the free-space propagation from the source plane to the far zone.

57 citations

Journal ArticleDOI
TL;DR: In this article, the authors control both shape and coherence using liquid-crystal spatial light modulators, and can produce two different classes of PCBs using the same simple optical setup.
Abstract: Partially coherent beams (PCBs) of light can be highly directional, as from lasers, yet resistant to speckle and scintillation, as from LEDs. Generating PCBs with separate optical components for beam shaping and spatial coherence is complicated, and fundamentally limited. The authors control both shape and coherence using liquid-crystal spatial light modulators, and can produce two different classes of PCBs using the same simple optical setup. This work is immediately applicable in such diverse fields as medicine, directed energy, free-space optical communication, and manufacturing.

51 citations

Journal ArticleDOI
TL;DR: For a partially coherent beam that is not too far removed from a coherent beam, the wave-optics results tend to the gamma-gamma model for the weak fluctuation regime and the results are closer to the lognormal models for the strong fluctuations regime.
Abstract: We examine the gamma-gamma and lognormal distributions as they apply to the irradiance at a point detector produced by partially coherent beams propagating horizontally through atmospheric turbulence. Our investigation compares the probability density functions and probability of fade predicted by the distributions with results from a wave-optics simulation developed for partially coherent beam propagation. For a partially coherent beam that is not too far removed from a coherent beam, we find the wave-optics results tend to the gamma-gamma model for the weak fluctuation regime and the results are closer to the lognormal model for the strong fluctuation regime. We observe that increasing the initial beam size/Fried parameter ratio (w0/r0) or shortening the coherence length (lc) tends to narrow the probability density profile produced by the simulation.

51 citations


Cited by
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Journal Article
J. Walkup1
TL;DR: Development of this more comprehensive model of the behavior of light draws upon the use of tools traditionally available to the electrical engineer, such as linear system theory and the theory of stochastic processes.
Abstract: Course Description This is an advanced course in which we explore the field of Statistical Optics. Topics covered include such subjects as the statistical properties of natural (thermal) and laser light, spatial and temporal coherence, effects of partial coherence on optical imaging instruments, effects on imaging due to randomly inhomogeneous media, and a statistical treatment of the detection of light. Development of this more comprehensive model of the behavior of light draws upon the use of tools traditionally available to the electrical engineer, such as linear system theory and the theory of stochastic processes.

1,364 citations

10 Jul 1986
TL;DR: In this paper, a multispectral image was modeled as mixtures of reflectance spectra of palagonite dust, gray andesitelike rock, and a coarse rock-like soil.
Abstract: A Viking Lander 1 image was modeled as mixtures of reflectance spectra of palagonite dust, gray andesitelike rock, and a coarse rocklike soil. The rocks are covered to varying degrees by dust but otherwise appear unweathered. Rocklike soil occurs as lag deposits in deflation zones around stones and on top of a drift and as a layer in a trench dug by the lander. This soil probably is derived from the rocks by wind abrasion and/or spallation. Dust is the major component of the soil and covers most of the surface. The dust is unrelated spectrally to the rock but is equivalent to the global-scale dust observed telescopically. A new method was developed to model a multispectral image as mixtures of end-member spectra and to compare image spectra directly with laboratory reference spectra. The method for the first time uses shade and secondary illumination effects as spectral end-members; thus the effects of topography and illumination on all scales can be isolated or removed. The image was calibrated absolutely from the laboratory spectra, in close agreement with direct calibrations. The method has broad applications to interpreting multispectral images, including satellite images.

1,107 citations

Journal ArticleDOI
TL;DR: The last volume of the Progress in Optics series as discussed by the authors contains seven chapters on widely diverging topics, written by well-known authorities in their fields, including laser selective photophysics and photochemistry, laser phase profile generation, laser beamforming, and laser laser light emission from high-current surface spark discharges.
Abstract: Have you ever felt that the very title, Progress in Optics, conjured an image in your mind? Don’t you see a row of handsomely printed books, bearing the editorial stamp of one of the most brilliant members of the optics community, and chronicling the field of optics since the invention of the laser? If so, you are certain to move the bookend to make room for Volume 16, the latest of this series. It contains seven chapters on widely diverging topics, written by well-known authorities in their fields. These are: 1) Laser Selective Photophysics and Photochemistry by V. S. Letokhov, 2) Recent Advances in Phase Profiles (sic) Generation by J. J. Clair and C. I. Abitbol, 3 ) Computer-Generated Holograms: Techniques and Applications by W.-H. Lee, 4) Speckle Interferometry by A. E. Ennos, 5 ) Deformation Invariant, Space-Variant Optical Pattern Recognition by D. Casasent and D. Psaltis, 6) Light Emission from High-Current Surface-Spark Discharges by R. E. Beverly, and 7) Semiclassical Radiation Theory within a QuantumMechanical Framework by I. R. Senitzkt. The breadth of topic matter spanned by these chapters makes it impossible, for this reviewer at least, to pass judgement on the comprehensiveness, relevance, and completeness of every chapter. With an editorial board as prominent as that of Progress in Optics, however, it seems hardly likely that such comments should be necessary. It should certainly be possible to take the authority of each author as credible. The only remaining judgment to be made on these chapters is their readability. In short, what are they like to read? The first sentence of the first chapter greets the eye with an obvious typographical error: “The creation of coherent laser light source, that have tunable radiation, opened the . . . .” Two pages later we find: “When two types of atoms or molecules of different isotopic composition ( A and B ) have even one spectral line that does not overlap with others, it is pos-

1,071 citations

Journal ArticleDOI
TL;DR: In this paper, a linear system, Fourier transform and Optica Acta: International Journal of Optics: Vol. 26, No. 7, pp. 836-836.
Abstract: (1979). Linear Systems, Fourier Transforms and Optics. Optica Acta: International Journal of Optics: Vol. 26, No. 7, pp. 836-836.

332 citations