Determination of First-Order Derivatives of Skew Ray at Aspherical Surface

• Psang Dain Lin and Chung Tsai
• received 01/10/2012; accepted 02/02/2012; posted 02/02/2012; Doc. ID 161253
• [full text: PDF (1099) KB)]
• Abstract: A set of algorithms is proposed for determining the first-order derivatives of a skew-ray with respect to all the independent variables of an aspherical boundary surface in general 3-D optical systems. Ellipsoidal, paraboloidal, hyperboloidal and cylindrical boundary surfaces are given as examples. The proposed method has important applications in the design of aspherical surfaces and enables a detailed understanding of a wide variety of optical effects, including reflection and refraction, the modulation transfer function (MTF), and aberrations.

Keywords (OCIS):

• (080.2720) Geometric optics : Mathematical methods (general)
• (080.2740) Geometric optics : Geometric optical design
• (080.1753) Geometric optics : Computation methods
• (080.2468) Geometric optics : First-order optics

General State Contrast Imaging : an optimized polarimetric imaging modality insensitive to spatial intensity fluctuations

• Guillaume Anna, Francois Goudail, and Daniel Dolfi
• received 12/13/2011; accepted 02/01/2012; posted 02/02/2012; Doc. ID 159887
• [full text: PDF (496) KB)]
• Abstract: In active polarization imaging, one frequently needs to be insensitive to non-informative intensity fluctuations. We investigate a way of solving this issue with General State Contrast (GSC) imaging. It consists in acquiring two scalar polarimetric images with optimized illumination and analysis polarization states, and forming a ratio. We propose a method for maximizing the discrimination ability between a target and a background in GSC images by determining the optimal illumination and analysis states. A further advantage of this approach is to provide an objective way of quantifying the performance improvement obtained by increasing the number of degrees of freedom of a GSC imager. The efficiency of this approach is demonstrated on simulated and real-world images.

Keywords (OCIS):

• (100.0100) Image processing : Image processing
• (110.5405) Imaging systems : Polarimetric imaging

Common omissions and misconceptions of wave propagation in turbulence

• Mikhail Charnotskii
• received 11/10/2011; accepted 01/31/2012; posted 02/02/2012; Doc. ID 158079
• [full text: PDF (1099) KB)]
• Abstract: This review paper is addressing typical mistakes and omissions that involve theoretical research and modeling of optical propagation through atmospheric turbulence. We discuss the disregard of some general properties of narrow-angle propagation in refractive random media, the careless use of simplified models of turbulence, and omissions in the calculations of the second moment of the propagating wave. We also review some misconceptions regarding short-exposure imaging, propagation of polarized waves, and calculations of the scintillation index of the beam waves.

Keywords (OCIS):

• (010.1300) Atmospheric and oceanic optics : Atmospheric propagation
• (010.1330) Atmospheric and oceanic optics : Atmospheric turbulence
• (030.1670) Coherence and statistical optics : Coherent optical effects
• (030.7060) Coherence and statistical optics : Turbulence
• (110.4850) Imaging systems : Optical transfer functions
• (110.0115) Imaging systems : Imaging through turbulent media

(ICVS) Color tuning in alert macaque V1 assessed with fMRI and single-unit recording shows a bias towards daylight colors

• Rosa Lafer-Sousa, Yang Liu, Luis Lafer-Sousa, Michael Wiest, and Bevil Conway
• received 09/27/2011; accepted 01/28/2012; posted 01/31/2012; Doc. ID 155222
• [full text: PDF (900) KB)]
• Abstract: The physiological basis for color is thought to depend on two populations of neurons in the lateral geniculate nucleus, which are presumed to underlie the cardinal chromatic mechanisms described psychophysically. Here we address the mechanisms by which the visual cortex combines input from the two subcortical channels by evaluating the population color tuning of macaque primary visual cortex (V1) using functional magnetic resonance imaging (fMRI) and single-unit recording. We found a slightly larger fMRI response to colors modulated along the orange-cyan intermediate direction in color space over colors modulated along the green-magenta intermediate direction, even though both stimulus conditions should elicit the same response from the canonical subcortical channels. Moreover, we found that the cone inputs of cone-opponent cells predict a color tuning that is also biased towards the orange-cyan intermediate axis. Under viewing conditions adapted to neutral gray, the chromaticity of daylight progresses along the orange-cyan intermediate axis. The results described here suggest the intriguing possibility that the visual system is adapted to daylight, the conditions under which the system evolved.

Keywords (OCIS):

• (330.1690) Vision, color, and visual optics : Color
• (330.1720) Vision, color, and visual optics : Color vision
• (330.4270) Vision, color, and visual optics : Vision system neurophysiology
• (330.4300) Vision, color, and visual optics : Vision system - noninvasive assessment
• (330.5380) Vision, color, and visual optics : Physiology

High order integral equation method for diffraction gratings

• Wangtao Lu and Ya Yan Lu
• received 01/03/2012; accepted 01/26/2012; posted 02/02/2012; Doc. ID 160716
• [full text: PDF (300) KB)]
• Abstract: Conventional integral equation methods for diffraction gratings require lattice sum techniques to evaluate quasi-periodic Green's functions. The boundary integral equation Neumann-to-Dirichlet map (BIE-NtD) method (Wu et al., J. Opt. Soc. Am. A 26, 2444-2451, 2009; 28, 1191-1196, 2011) is a recently developed integral equation method that avoids the quasi-periodic Green's functions and is relatively easy to implement. In this paper, we present a number of improvements for this method, including a revised formulation that is more stable numerically, and more accurate methods for computing tangential derivatives along material interfaces and for matching boundary conditions with the homogeneous top and bottom regions. Numerical examples indicate that the improved BIE-DtN map method achieves high order of accuracy for in-plane and conical diffractions of dielectric gratings.

Keywords (OCIS):

• (050.1960) Diffraction and gratings : Diffraction theory
• (050.1755) Diffraction and gratings : Computational electromagnetic methods

Solid-immersion imaging interferometric nanoscopy to the limits of available frequency space

• Yuliya Kuznetsova, Alexander Neumann, and Steven Brueck
• received 12/06/2011; accepted 01/25/2012; posted 01/27/2012; Doc. ID 159309
• [full text: PDF (1228) KB)]
• Abstract: Imaging interferometric nanoscopy (IIN) is a synthetic aperture approach offering the potential of optical resolution to the linear systems limit of optics (~/4n). The immersion advantages of IIN can be realized if the object is in close proximity to a solid-immersion medium with illumi-nation and collection through the substrate and coupling this radiation to air by a grating on the medium surface opposite the object. The spatial resolution as a function of the medium thickness and refractive index as well as the field-of-view of the objective optical system is derived and applied to simulations.

Keywords (OCIS):

• (110.0110) Imaging systems : Imaging systems
• (180.0180) Microscopy : Microscopy

The interim connection space based on human color vision for spectral color reproduction

• Xiandou Zhang, Qiang Wang, JinCheng Li, Ping Yang, and Jieyue Yu
• received 10/11/2011; accepted 01/24/2012; posted 01/24/2012; Doc. ID 156205
• [full text: PDF (363) KB)]
• Abstract: To improve the spectral image color reproduction accuracy, two novel interim connection space (ICS) were proposed. The dominant structure of spectral power distributions were extracted by principal component analysis for the widely used illuminants and light sources, and then further transformed to three synthetic illuminants. The CIEXYZ tristimulus under two or three synthetic illuminants are employed to construct two novel ICS. The two ICS were compared with LabPQR and the ICS with two sets of tristimulus under two really light sources according to the spectral and colorimetric representing accuracy of Munsell and NCS chips. The results indicated that the two ICS proposed in this study outperformed the other two ICS as a whole.

Keywords (OCIS):

• (330.1730) Vision, color, and visual optics : Colorimetry
• (330.1715) Vision, color, and visual optics : Color, rendering and metamerism

Three-Dimensional Resolvability in an Integral Imaging System

• Zahra Kavehvash, Manuel Martinez-Corral, Khashayar Mehrany, Saeed Bagheri, Genaro Saavedra, and Hector Navarro
• received 11/22/2011; accepted 01/23/2012; posted 01/27/2012; Doc. ID 158712
• [full text: PDF (1821) KB)]
• Abstract: The concept of three dimensional (3D) resolvability of an integral imaging system is thoroughly investigated in this research. The general concept of 3D resolution fails to describe the 3D discrimination completely. Then, the concepts of depth-plane and resolution-plane need to be introduced to show the difference between conventional 3D spatial resolution and the newly introduced three-dimensional resolvability. Therefore, the different properties of these planes for differentiating lateral spatial variations and axial variations are analyzed in this paper. The theoretical statements are demonstrated experimentally.

Keywords (OCIS):

• (110.3000) Imaging systems : Image quality assessment
• (110.6880) Imaging systems : Three-dimensional image acquisition

TE and TM Pulsed Beam Decomposition of Time-dependent Aperture Fields

• Timor Melamed, Dor Abuhasira, and David Dayan
• received 12/16/2011; accepted 01/23/2012; posted 01/31/2012; Doc. ID 160155
• [full text: PDF (855) KB)]
• Abstract: The present contribution is concerned with applying beam-type expansion to planar aperture time-dependent electromagnetic field in which the propagating elements, the electromagnetic pulsed-beams, are \emph{a priori} decomposed into transverse electric (TE) and transverse magnetic (TM) field polarizations. The propagating field is described as a discrete superposition of tilted, shifted and delayed TE and TM electromagnetic pulsed-beams over the frame-based spectral lattice. These waveobjects are evaluated by using transient plane-wave spectral representations. Explicit asymptotic expressions for electromagnetic iso-diffracting pulsed-quadratic beam propagators are presented, as well as a numerical example.

Keywords (OCIS):

• (070.2580) Fourier optics and signal processing : Paraxial wave optics
• (080.2720) Geometric optics : Mathematical methods (general)
• (350.5500) Other areas of optics : Propagation

Extension of the Stokes equation for layered constructions to fluorescent turbid media

• Ludovic Coppel, Magnus Neuman, and Per Edström
• received 01/03/2012; accepted 01/20/2012; posted 01/24/2012; Doc. ID 160521
• [full text: PDF (344) KB)]
• Abstract: Expressions relating the bi-spectral reflectance of a stack of $n$ fluorescing layers to each individual layer reflectance and transmittance are derived. This theoretical framework is used together with recently proposed extensions of the Kubelka-Munk model to study the fluorescence from layered turbid media. For one layer over a reflecting background, the model is shown to give the same results as a previous model. The extension to $n$ layers with different optical properties allows simulating the bi-spectral reflectance from a pad of layered turbid media. The applicability of the model is exemplified with an optimization of fluorophore distribution in layered turbid media.

Keywords (OCIS):

• (260.2510) Physical optics : Fluorescence
• (290.4210) Scattering : Multiple scattering
• (290.7050) Scattering : Turbid media
• (330.1690) Vision, color, and visual optics : Color

Multiple-scattering model for the coherent reflection and transmission of light from a disordered monolayer of particles

• Augusto Garcia-Valenzuela, Edahí Gutierrez-Reyes, and Rubén Barrera
• received 09/15/2011; accepted 01/20/2012; posted 01/23/2012; Doc. ID 154647
• [full text: PDF (628) KB)]
• Abstract: We derive a multiple scattering model in closed form for the coherent reflection and transmission coefficients for electromagnetic plane waves from a random array of spherical particles in two dimensions. We use a rigorous scattering formalism and approximate the field exciting the particles with traveling plane waves while considering a hard-sphere correlation function. The size of the spheres with respect to the wavelength of radiation is unrestricted. The resulting model takes into account multiple scattering between the particles, allowing for any angle of incidence. The resulting formulas are relatively simple making the model suitable for optical sensing applications.

Keywords (OCIS):

• (290.4210) Scattering : Multiple scattering
• (290.5850) Scattering : Scattering, particles

Electrodynamics analysis on coherent perfect absorber and phase-controlled optical switch

• Tianjie Chen, Shaoguang Duan, and Ying-Chih Chen
• received 10/04/2011; accepted 01/19/2012; posted 01/19/2012; Doc. ID 155905
• [full text: PDF (520) KB)]
• Abstract: A coherent perfect absorber is essentially a specially designed Fabry-Perot interferometer, which completely extinguishes incident coherent light. The one- and two-beam coherent perfect absorbers are analyzed using classical electrodynamics, which presents a clear and physically intuitive picture of the principle of a perfect absorber. The results show that the incident beam(s) must have correct phases and amplitudes; and the real and imaginary parts of the refractive indices of the medium in the interferometer must match each other to satisfy a well defined relation. Our results are in agreement with those obtained from the S-matrix analysis. However, the occurrence of total absorption does not involve time reversal as does in the S-matrix analysis, nor does it exhibit a threshold behavior. Further analysis shows that the two-beam device also can be configured to function as a phase controlled three-state switch.

Keywords (OCIS):

• (030.1670) Coherence and statistical optics : Coherent optical effects
• (120.2230) Instrumentation, measurement, and metrology : Fabry-Perot
• (230.1150) Optical devices : All-optical devices
• (260.2160) Physical optics : Energy transfer
• (230.3750) Optical devices : Optical logic devices

Mechanism and symmetry properties of depolarization in weak scattering of light

• Yingjun He, Yu Xin, Dengping Wu, Liqiang Deng, and Yanru Chen
• received 12/20/2011; accepted 01/19/2012; posted 01/24/2012; Doc. ID 160212
• [full text: PDF (361) KB)]
• Abstract: The mechanism and some symmetry properties of depolarization upon weak scattering of light from a class of random media were studied theoretically. Departing from the angular distribution of the degree of polarization, our derivations showed the mechanism that induce the change of polarization can be split into two parts of different nature. One is the vectorial effect that redistributes the original light components and the other is the interaction effect of the medium that modulates the correlation properties of the incident field. We also showed that there is dependence of the angular distribution on the incident polarization state, i.e., the angular pattern and its symmetry depend on both the orientation and ellipticity of the incident polarization ellipse.

Keywords (OCIS):

• (030.0030) Coherence and statistical optics : Coherence and statistical optics
• (290.5855) Scattering : Scattering, polarization

The behaviour of the instantaneous Poynting vector of symmetrical laser beams

• Igor Litvin
• received 12/08/2011; accepted 01/19/2012; posted 01/23/2012; Doc. ID 159630
• [full text: PDF (1444) KB)]
• Abstract: In this work we investigate the behaviour of the instantaneous Poynting vector of symmetrical paraxial laser beams namely the modification of the instantaneous Poynting vector and the radiation pattern during propagation in free space for a variety of such beams. As an example we have investigated in detail the behaviour of the instantaneous Poynting vector and the radiation pattern of the paraxial Gaussian and Bessel beams.

Keywords (OCIS):

• (260.2110) Physical optics : Electromagnetic optics
• (140.3295) Lasers and laser optics : Laser beam characterization

3D Photon Counting Integral Imaging with Unknown Sensor Positions

• Xiao Xiao and Bahram Javidi
• received 11/07/2011; accepted 01/19/2012; posted 01/31/2012; Doc. ID 157796
• [full text: PDF (429) KB)]
• Abstract: Photon counting techniques have been introduced with integral imaging for 3D imaging applications. The previous reports in this area assumed a priori knowledge of exact sensor positions for 3D image reconstruction which may be difficult to satisfy in certain applications. In this paper, we extend photon counting 3D imaging system to situations where sensor positions are unknown. To estimate sensor positions in photon counting integral imaging, scene details of photon counting images are needed for image correspondences matching. Therefore, an iterative method based on total variation maximum a posteriori expectation maximization (MAP-EM) algorithm is used to restore photon counting images. Experimental results are presented to show the feasibility of the method. To the best of our knowledge, this is the first report on 3D photon counting integral imaging with unknown sensor positions.

Keywords (OCIS):

• (030.5260) Coherence and statistical optics : Photon counting
• (100.3020) Image processing : Image reconstruction-restoration
• (110.6880) Imaging systems : Three-dimensional image acquisition
• (150.6910) Machine vision : Three-dimensional sensing

Cross-polarization of Linearly Polarized Hermite-Gauss Laser Beams

• Jessica Conry, Reeta Vyas, and Surendra Singh
• received 09/02/2011; accepted 01/18/2012; posted 01/18/2012; Doc. ID 153792
• [full text: PDF (438) KB)]
• Abstract: Evolution of transverse intensity profiles for the dominant and cross-polarization components of linearly polarized Laguerre-Gauss laser beams is studied experimentally as the beams propagate away from their waist. Measured intensity profiles and their evolution with propagation are in good agreement with the theoretical predictions.

Keywords (OCIS):

• (140.3300) Lasers and laser optics : Laser beam shaping
• (260.5430) Physical optics : Polarization

Transmission properties in waveguides: An optical streamline analysis

• Ángel Sanz, José Campos-Martínez, and Salvador Miret-Artés
• received 10/25/2011; accepted 01/17/2012; posted 01/18/2012; Doc. ID 157105
• [full text: PDF (2931) KB)]
• Abstract: A novel approach to study transmission through waveguides in terms of optical streamlines is presented. This theoretical framework relies on the possibility to monitor the passage of light through the guiding medium by means of these sampler paths. In this way, not only the optical flow along the waveguide can be followed in detail, but also a fair estimate of the transmitted light (intensity) can be accounted for by counting arrivals of streamlines whose starting points distribute statistically according to the input pulse. Furthermore, this analysis also allows to clearly elucidate the mechanism leading to energy losses, which can be advantageously exploited in optimal waveguide design.

Keywords (OCIS):

• (060.2310) Fiber optics and optical communications : Fiber optics
• (220.2560) Optical design and fabrication : Propagating methods

Analysis of an optical resonator formed by a pair of specially shaped axicons

• Masamori Endo, Motoi Sasaki, and Ryoji Koseki
• received 09/15/2011; accepted 01/17/2012; posted 01/23/2012; Doc. ID 154661
• [full text: PDF (424) KB)]
• Abstract: A design for an optical resonator suited to using large-bore active media is proposed. The resonator consists of a pair of waxicons, so we call it a ``wwaxicon optical resonator.' The resonator is considered a solid resonator; it is surrounded by a series of ring resonators that are parallel to the optical axis. A numerical simulation of the resonator designed for use in a commercial CO2 laser is performed. It is found that parasitic oscillation modes can be suppressed by the use of an spatial-frequency restrictor.The resonator exhibits oscillation in the TEM01* transverse mode and produces twice as much output power as the 7-fold multipass stable optical resonator.

Keywords (OCIS):

• (140.3410) Lasers and laser optics : Laser resonators
• (220.1920) Optical design and fabrication : Diamond machining
• (260.5430) Physical optics : Polarization

Model-Resolution Based Regularization Improves Near Infrared Diffuse Optical Tomography

• Phaneendra Yalavarthy and Sree Harsha Katamreddy
• received 11/16/2011; accepted 01/17/2012; posted 01/24/2012; Doc. ID 158123
• [full text: PDF (447) KB)]
• Abstract: Diffuse optical tomographic imaging is known to be a ill-posed problem and a penalty/regularization term is used in image reconstruction (inverse problem) to over come this limitation. Two schemes that are prelevant are spatially-varying (exponential) and constant (standard) regularizations/penalties. A new scheme that is also spatially varying but uses the model information is introduced based on the model-resolution matrix. The new scheme along with exponential and standard regularization schemes are evaluated objectively based on model-resolution and data-resolution matrices. This objective analysis showed that resolution characteristics are better for spatially-varying penalties compared to standard regularization and among spatially-varying regularization schemes the model-resolution based regularization has better data-resolution and model-resolution characteristics. The verification of the same is achieved by performing numerical experiments in reconstructing numerically generated 1% noisy data involving simple two- and three-dimensional imaging domains.

Keywords (OCIS):

• (170.0170) Medical optics and biotechnology : Medical optics and biotechnology
• (170.3010) Medical optics and biotechnology : Image reconstruction techniques
• (170.6960) Medical optics and biotechnology : Tomography

Analytical Expressions for the log-amplitude correlation function of a plane wave through anisotropic atmospheric refractive turbulence

• V. S. Rao Gudimetla, Richard Holmes, Carey Smith, and Gregory Needham
• received 09/01/2011; accepted 01/16/2012; posted 01/27/2012; Doc. ID 153795
• [full text: PDF (561) KB)]
• Abstract: The effect of anisotropic Kolmogorov turbulence on the log-amplitude correlation function for plane wave fields is investigated using analysis, numerical integration and simulation. A new analytical expression for the log-amplitude correlation function is derived for anisotropic Kolmogorov turbulence. The analytic results, based on the Rytov approximation, agree well with a more general wave-optics simulation based on the Fresnel approximation as well as with numerical evaluations, for low and moderate strengths of turbulence. The new expression reduces correctly to previously-published analytic expressions for isotropic turbulence. The final results indicate that as asymmetry becomes greater, the Rytov variance deviates from that given by the simple formula. This deviation from the Rytov variance becomes greater with stronger turbulence (up to moderate turbulence strengths). The anisotropic effects on the log-amplitude correlation function are dominant when the separation of the points is within the Fresnel length. In the direction of stronger turbulence, there is an enhanced dip in the correlation function at a separation close to the Fresnel length. The dip is diminished in the weak-turbulence axis, suggesting that energy redistribution via focusing and defocusing is dominated by the strongturbulence axis. The new analytical expression is useful when anisotropy is observed in relevant experiments.

Keywords (OCIS):

• (010.1290) Atmospheric and oceanic optics : Atmospheric optics
• (010.1300) Atmospheric and oceanic optics : Atmospheric propagation