Spherical mirror mount

NASA Technical Reports Server (NTRS)

Meyer, Jay L. (Inventor); Messick, Glenn C. (Inventor); Nardell, Carl A. (Inventor); Hendlin, Martin J. (Inventor)

2011-01-01

A spherical mounting assembly for mounting an optical element allows for rotational motion of an optical surface of the optical element only. In that regard, an optical surface of the optical element does not translate in any of the three perpendicular translational axes. More importantly, the assembly provides adjustment that may be independently controlled for each of the three mutually perpendicular rotational axes.

One-dimensional ion-beam figuring for grazing-incidence reflective optics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Lin; Idir, Mourad; Bouet, Nathalie

2016-01-01

One-dimensional ion-beam figuring (1D-IBF) can improve grazing-incidence reflective optics, such as Kirkpatrick–Baez mirrors. 1D-IBF requires only one motion degree of freedom, which reduces equipment complexity, resulting in compact and low-cost IBF instrumentation. Furthermore, 1D-IBF is easy to integrate into a single vacuum system with other fabrication processes, such as a thin-film deposition. The NSLS-II Optical Metrology and Fabrication Group has recently integrated the 1D-IBF function into an existing thin-film deposition system by adding an RF ion source to the system. Using a rectangular grid, a 1D removal function needed to perform 1D-IBF has been produced. In this paper, demonstration experimentsmore » of the 1D-IBF process are presented on one spherical and two plane samples. The final residual errors on both plane samples are less than 1 nm r.m.s. In conclusion, the surface error on the spherical sample has been successfully reduced by a factor of 12. The results show that the 1D-IBF method is an effective method to process high-precision 1D synchrotron optics.« less

Photonic polymer-blend structures and method for making

DOEpatents

Barnes, Michael D.

2004-06-29

The present invention comprises the formation of photonic polymer-blend structures having tunable optical and mechanical properties. The photonic polymer-blend structures comprise monomer units of spherical microparticles of a polymer-blend material wherein the spherical microparticles have surfaces partially merged with one another in a robust inter-particle bond having a tunable inter-particle separation or bond length sequentially attached in a desired and programmable architecture. The photonic polymer-blend structures of the present invention can be linked by several hundred individual particles sequentially linked to form complex three-dimensional structures or highly ordered two-dimensional arrays of 3D columns with 2D spacing.

Mathematical Methods for Optical Physics and Engineering

NASA Astrophysics Data System (ADS)

Gbur, Gregory J.

2011-01-01

1. Vector algebra; 2. Vector calculus; 3. Vector calculus in curvilinear coordinate systems; 4. Matrices and linear algebra; 5. Advanced matrix techniques and tensors; 6. Distributions; 7. Infinite series; 8. Fourier series; 9. Complex analysis; 10. Advanced complex analysis; 11. Fourier transforms; 12. Other integral transforms; 13. Discrete transforms; 14. Ordinary differential equations; 15. Partial differential equations; 16. Bessel functions; 17. Legendre functions and spherical harmonics; 18. Orthogonal functions; 19. Green's functions; 20. The calculus of variations; 21. Asymptotic techniques; Appendices; References; Index.

Four-mirror extreme ultraviolet (EUV) lithography projection system

DOEpatents

Cohen, Simon J; Jeong, Hwan J; Shafer, David R

2000-01-01

The invention is directed to a four-mirror catoptric projection system for extreme ultraviolet (EUV) lithography to transfer a pattern from a reflective reticle to a wafer substrate. In order along the light path followed by light from the reticle to the wafer substrate, the system includes a dominantly hyperbolic convex mirror, a dominantly elliptical concave mirror, spherical convex mirror, and spherical concave mirror. The reticle and wafer substrate are positioned along the system's optical axis on opposite sides of the mirrors. The hyperbolic and elliptical mirrors are positioned on the same side of the system's optical axis as the reticle, and are relatively large in diameter as they are positioned on the high magnification side of the system. The hyperbolic and elliptical mirrors are relatively far off the optical axis and hence they have significant aspherical components in their curvatures. The convex spherical mirror is positioned on the optical axis, and has a substantially or perfectly spherical shape. The spherical concave mirror is positioned substantially on the opposite side of the optical axis from the hyperbolic and elliptical mirrors. Because it is positioned off-axis to a degree, the spherical concave mirror has some asphericity to counter aberrations. The spherical concave mirror forms a relatively large, uniform field on the wafer substrate. The mirrors can be tilted or decentered slightly to achieve further increase in the field size.

Optical bullets and "rockets" in nonlinear dissipative systems and their transformations and interactions.

PubMed

Soto-Crespo, J M; Grelu, Philippe; Akhmediev, Nail

2006-05-01

We demonstrate the existence of stable optical light bullets in nonlinear dissipative media for both cases of normal and anomalous chromatic dispersion. The prediction is based on direct numerical simulations of the (3+1)-dimensional complex cubic-quintic Ginzburg-Landau equation. We do not impose conditions of spherical or cylindrical symmetry. Regions of existence of stable bullets are determined in the parameter space. Beyond the domain of parameters where stable bullets are found, unstable bullets can be transformed into "rockets" i.e. bullets elongated in the temporal domain. A few examples of the interaction between two optical bullets are considered using spatial and temporal interaction planes.

Iron Oxide and Gold Based Magneto-Plasmonic Nanostructures for Medical Applications: A Review

PubMed Central

Mammeri, Fayna; Ammar, Souad

2018-01-01

Iron oxide and gold-based magneto-plasmonic nanostructures exhibit remarkable optical and superparamagnetic properties originating from their two different components. As a consequence, they have improved and broadened the application potential of nanomaterials in medicine. They can be used as multifunctional nanoprobes for magneto-plasmonic heating as well as for magnetic and optical imaging. They can also be used for magnetically assisted optical biosensing, to detect extreme traces of targeted bioanalytes. This review introduces the previous work on magneto-plasmonic hetero-nanostructures including: (i) their synthesis from simple “one-step” to complex “multi-step” routes, including seed-mediated and non-seed-mediated methods; and (ii) the characterization of their multifunctional features, with a special emphasis on the relationships between their synthesis conditions, their structures and their properties. It also focuses on the most important progress made with regard to their use in nanomedicine, keeping in mind the same aim, the correlation between their morphology—namely spherical and non-spherical, core-satellite and core-shell, and the desired applications. PMID:29518969

Multiphoton imaging microscopy at deeper layers with adaptive optics control of spherical aberration.

PubMed

Bueno, Juan M; Skorsetz, Martin; Palacios, Raquel; Gualda, Emilio J; Artal, Pablo

2014-01-01

Despite the inherent confocality and optical sectioning capabilities of multiphoton microscopy, three-dimensional (3-D) imaging of thick samples is limited by the specimen-induced aberrations. The combination of immersion objectives and sensorless adaptive optics (AO) techniques has been suggested to overcome this difficulty. However, a complex plane-by-plane correction of aberrations is required, and its performance depends on a set of image-based merit functions. We propose here an alternative approach to increase penetration depth in 3-D multiphoton microscopy imaging. It is based on the manipulation of the spherical aberration (SA) of the incident beam with an AO device while performing fast tomographic multiphoton imaging. When inducing SA, the image quality at best focus is reduced; however, better quality images are obtained from deeper planes within the sample. This is a compromise that enables registration of improved 3-D multiphoton images using nonimmersion objectives. Examples on ocular tissues and nonbiological samples providing different types of nonlinear signal are presented. The implementation of this technique in a future clinical instrument might provide a better visualization of corneal structures in living eyes.

Modelling of influence of spherical aberration coefficients on depth of focus of optical systems

NASA Astrophysics Data System (ADS)

Pokorný, Petr; Šmejkal, Filip; Kulmon, Pavel; Mikš, Antonín.; Novák, Jiří; Novák, Pavel

2017-06-01

This contribution describes how to model the influence of spherical aberration coefficients on the depth of focus of optical systems. Analytical formulas for the calculation of beam's caustics are presented. The conditions for aberration coefficients are derived for two cases when we require that either the Strehl definition or the gyration radius should be the identical in two symmetrically placed planes with respect to the paraxial image plane. One can calculate the maximum depth of focus and the minimum diameter of the circle of confusion of the optical system corresponding to chosen conditions. This contribution helps to understand how spherical aberration may affect the depth of focus and how to design such an optical system with the required depth of focus. One can perform computer modelling and design of the optical system and its spherical aberration in order to achieve the required depth of focus.

Wide field strip-imaging optical system

NASA Technical Reports Server (NTRS)

Vaughan, Arthur H. (Inventor)

1994-01-01

A strip imaging wide angle optical system is provided. The optical system is provided with a 'virtual' material stop to avoid aberrational effects inherent in wide angle optical systems. The optical system includes a spherical mirror section for receiving light from a 180-degree strip or arc of a target image. Light received by the spherical mirror section is reflected to a frusto-conical mirror section for subsequent rereflection to a row of optical fibers. Each optical fiber transmits a portion of the received light to a detector. The optical system exploits the narrow cone of acceptance associated with optical fibers to substantially eliminate vignetting effects inherent in wide-angle systems. Further, the optical system exploits the narrow cone of acceptance of the optical fibers to substantially limit spherical aberration. The optical system is ideally suited for any application wherein a 180-degree strip image need be detected, and is particularly well adapted for use in hostile environments such as in planetary exploration.

Spherical Coordinate Systems for Streamlining Suited Mobility Analysis

NASA Technical Reports Server (NTRS)

Benson, Elizabeth; Cowley, Matthew; Harvill, Lauren; Rajulu. Sudhakar

2015-01-01

Introduction: When describing human motion, biomechanists generally report joint angles in terms of Euler angle rotation sequences. However, there are known limitations in using this method to describe complex motions such as the shoulder joint during a baseball pitch. Euler angle notation uses a series of three rotations about an axis where each rotation is dependent upon the preceding rotation. As such, the Euler angles need to be regarded as a set to get accurate angle information. Unfortunately, it is often difficult to visualize and understand these complex motion representations. It has been shown that using a spherical coordinate system allows Anthropometry and Biomechanics Facility (ABF) personnel to increase their ability to transmit important human mobility data to engineers, in a format that is readily understandable and directly translatable to their design efforts. Objectives: The goal of this project was to use innovative analysis and visualization techniques to aid in the examination and comprehension of complex motions. Methods: This project consisted of a series of small sub-projects, meant to validate and verify a new method before it was implemented in the ABF's data analysis practices. A mechanical test rig was built and tracked in 3D using an optical motion capture system. Its position and orientation were reported in both Euler and spherical reference systems. In the second phase of the project, the ABF estimated the error inherent in a spherical coordinate system, and evaluated how this error would vary within the reference frame. This stage also involved expanding a kinematic model of the shoulder to include the rest of the joints of the body. The third stage of the project involved creating visualization methods to assist in interpreting motion in a spherical frame. These visualization methods will be incorporated in a tool to evaluate a database of suited mobility data, which is currently in development. Results: Initial results demonstrated that a spherical coordinate system is helpful in describing and visualizing the motion of a space suit. The system is particularly useful in describing the motion of the shoulder, where multiple degrees of freedom can lead to very complex motion paths.

Wide-angle imaging system with fiberoptic components providing angle-dependent virtual material stops

NASA Technical Reports Server (NTRS)

Vaughan, Arthur H. (Inventor)

1993-01-01

A strip imaging wide angle optical system is provided. The optical system is provided with a 'virtual' material stop to avoid aberrational effects inherent in wide angle optical systems. The optical system includes a spherical mirror section for receiving light from a 180 deg strip or arc of a target image. Light received by the spherical mirror section is reflected to a frustoconical mirror section for subsequent rereflection to a row of optical fibers. Each optical fiber transmits a portion of the received light to a detector. The optical system exploits the narrow cone of acceptance associated with optical fibers to substantially eliminate vignetting effects inherent in wide angle systems. Further, the optical system exploits the narrow cone of acceptance of the optical fibers to substantially limit spherical aberration. The optical system is ideally suited for any application wherein a 180 deg strip image need be detected, and is particularly well adapted for use in hostile environments such as in planetary exploration.

Ultrafast all-optical technologies for bidirectional optical wireless communications.

PubMed

Jin, Xian; Hristovski, Blago A; Collier, Christopher M; Geoffroy-Gagnon, Simon; Born, Brandon; Holzman, Jonathan F

2015-04-01

In this Letter, a spherical retro-modulator architecture is introduced for operation as a bidirectional transceiver in passive optical wireless communication links. The architecture uses spherical retroreflection to enable retroreflection with broad directionality (2π steradians), and it uses all-optical beam interaction to enable modulation on ultrafast timescales (120 fs duration). The spherical retro-modulator is investigated from a theoretical standpoint and is fabricated for testing with three glasses, N-BK7, N-LASF9, and S-LAH79. It is found that the S-LAH79 structure provides the optimal refraction and nonlinearity for the desired retroreflection and modulation capabilities.

Electron Optics for Biologists: Physical Origins of Spherical Aberrations

ERIC Educational Resources Information Center

Geissler, Peter; Zadunaisky, Jose

1974-01-01

Reports on the physical origins of spherical aberrations in axially symmetric electrostatic lenses to convey the essentials of electon optics to those who must think critically about the resolution of the electron microscope. (GS)

Variations on a theme: novel immersed grating based spectrometer designs for space

NASA Astrophysics Data System (ADS)

Agócs, T.; Navarro, R.; Venema, L.

2017-11-01

We present novel immersed grating (IG) based spectrometer designs that can be used in space instrumentation. They are based on the design approach that aims to optimize the optical design using the expanded parameter space that the IG technology offers. In principle the wavefront error (WFE) of any optical system the most conveniently can be corrected in the pupil, where in the case of the IG based spectrometer, the IG itself is positioned. By modifying existing three-mirror based optical systems, which can form the main part of double pass spectrometer designs, a large portion of the WFE of the optical system can be transferred to the pupil and to the IG. In these cases the IG can compensate simple low order aberrations of the system and consequently the main benefit is that the mirrors that tend to be off-axis conical sections can be substituted by spherical mirrors. The WFE budget of such designs has only a minor contribution from the very high quality spherical mirrors and the majority of the WFE can be then allocated to the most complex part of the system, the IG. The latter can be designed so that the errors are compensated by a special grating pattern that in turn can be manufactured using the expertise and experience of the semiconductor industry.

Retrieving the aerosol complex refractive index using PyMieScatt: A Mie computational package with visualization capabilities

NASA Astrophysics Data System (ADS)

Sumlin, Benjamin J.; Heinson, William R.; Chakrabarty, Rajan K.

2018-01-01

The complex refractive index m = n + ik of a particle is an intrinsic property which cannot be directly measured; it must be inferred from its extrinsic properties such as the scattering and absorption cross-sections. Bohren and Huffman called this approach "describing the dragon from its tracks", since the inversion of Lorenz-Mie theory equations is intractable without the use of computers. This article describes PyMieScatt, an open-source module for Python that contains functionality for solving the inverse problem for complex m using extensive optical and physical properties as input, and calculating regions where valid solutions may exist within the error bounds of laboratory measurements. Additionally, the module has comprehensive capabilities for studying homogeneous and coated single spheres, as well as ensembles of homogeneous spheres with user-defined size distributions, making it a complete tool for studying the optical behavior of spherical particles.

Enhancing photothermal cancer therapy by clustering gold nanoparticles into spherical polymeric nanoconstructs

NASA Astrophysics Data System (ADS)

Iodice, Carmen; Cervadoro, Antonio; Palange, AnnaLisa; Key, Jaehong; Aryal, Santosh; Ramirez, Maricela R.; Mattu, Clara; Ciardelli, Gianluca; O'Neill, Brian E.; Decuzzi, Paolo

2016-01-01

Gold nanoparticles (AuNPs) have been proposed as agents for enhancing photothermal therapy in cancer and cardiovascular diseases. Different geometrical configurations have been used, ranging from spheres to rods and more complex star shapes, to modulate optical and ablating properties. In this work, multiple, ultra-small 6 nm AuNPs are encapsulated into larger spherical polymeric nanoconstructs (SPNs), made out of a poly(lactic acid-co-glycol acid) (PLGA) core stabilized by a superficial lipid-PEG monolayer. The optical and photothermal properties of the resulting nanoconstructs (Au-SPNs) are modulated by varying the initial loading input of AuNPs, ranging between 25 and 150 μgAu. Au-SPNs exhibit a hydrodynamic diameter varying from ~100 to 180 nm, growing with the gold content, and manifest up to 2-fold increase in thermal energy production per unit mass of gold for an initial input of 100 μgAu. Au-SPNs are stable under physiological conditions up to 7 days and have direct cytotoxic effect on tumor cells. The superior photothermal performance of Au-SPNs is assessed in vitro on monolayers of breast cancer cells (SUM-159) and tumor spheroids of glioblastoma multiforme cells (U87-MG). The encapsulation of small AuNPs into larger spherical nanoconstructs enhances photothermal ablation and could favor tumor accumulation.

Repeatability of Spectral Domain Optical Coherence Tomography Measurements in High Myopia.

PubMed

Rao, Harsha L; Kumar, Addepalli U; Bonala, Sampath R; Yogesh, Kadam; Lakshmi, Bodduluri

2016-05-01

The purpose of this study was to compare the repeatability of spectral domain optical coherence tomography (SDOCT) parameters in high-myopic and emmetropic healthy subjects, and to evaluate the influence of axial length on the repeatability of SDOCT parameters in high myopia. In a prospective study, 93 eyes of 63 high-myopic subjects (spherical refractive error, -6 to -12 D; median age, 25 y) and 28 eyes of 14 emmetropic (spherical refractive error, 0 D; median age, 30 y) subjects underwent optic nerve head, retinal nerve fiber layer (RNFL), and ganglion cell complex imaging with SDOCT. For the repeatability analysis, 31 eyes of 31 high-myopic subjects and 14 eyes of 14 emmetropic subjects underwent 3 repeated scans in the same session. Among the optic nerve head parameters, within-subject coefficient of variation (CVw) measurements of the disc area (0.6% vs. 0.2%), rim area (8.7 vs. 2.8), and rim volume (16.7 vs. 8.9) were significantly larger (worse) in high-myopic compared with the emmetropic subjects. CVw measurements of all RNFL (range, 1.7 to 22.4) and ganglion cell complex (range, 1.8 to 2.5) parameters in high-myopic subjects were comparable to that in emmetropic subjects (2.4 to 24.0 and 1.7 to 2.0, respectively). Axial length significantly affected the CVw of nasal (coefficient, 0.01; P=0.04) and average RNFL (coefficient, 0.004; P=0.001) parameters but not that of the other SDOCT parameters. Repeatabilities of most of the SDOCT parameters in high-myopic subjects were good and comparable to that of emmetropic subjects. This suggests that SDOCT can be useful for following up high-myopic glaucoma patients to detect progression.

Spherical mirror grazing incidence x-ray optics

NASA Technical Reports Server (NTRS)

Cash, Jr., Webster C. (Inventor)

1997-01-01

An optical system for x-rays combines at least two spherical or near spherical mirrors for each dimension in grazing incidence orientation to provide the functions of a lens in the x-ray region. To focus x-ray radiation in both the X and the Y dimensions, one of the mirrors focusses the X dimension, a second mirror focusses the Y direction, a third mirror corrects the X dimension by removing comatic aberration and a fourth mirror corrects the Y dimension. Spherical aberration may also be removed for an even better focus. The order of the mirrors is unimportant.

Theoretical model for design and analysis of protectional eyewear.

PubMed

Zelzer, B; Speck, A; Langenbucher, A; Eppig, T

2013-05-01

Protectional eyewear has to fulfill both mechanical and optical stress tests. To pass those optical tests the surfaces of safety spectacles have to be optimized to minimize optical aberrations. Starting with the surface data of three measured safety spectacles, a theoretical spectacle model (four spherical surfaces) is recalculated first and then optimized while keeping the front surface unchanged. Next to spherical power, astigmatic power and prism imbalance we used the wavefront error (five different viewing directions) to simulate the optical performance and to optimize the safety spectacle geometries. All surfaces were spherical (maximum global deviation 'peak-to-valley' between the measured surface and the best-fit sphere: 0.132mm). Except the spherical power of the model Axcont (-0.07m(-1)) all simulated optical performance before optimization was better than the limits defined by standards. The optimization reduced the wavefront error by 1% to 0.150 λ (Windor/Infield), by 63% to 0.194 λ (Axcont/Bolle) and by 55% to 0.199 λ (2720/3M) without dropping below the measured thickness. The simulated optical performance of spectacle designs could be improved when using a smart optimization. A good optical design counteracts degradation by parameter variation throughout the manufacturing process. Copyright © 2013. Published by Elsevier GmbH.

Electro-optic spatial decoding on the spherical-wavefront Coulomb fields of plasma electron sources.

PubMed

Huang, K; Esirkepov, T; Koga, J K; Kotaki, H; Mori, M; Hayashi, Y; Nakanii, N; Bulanov, S V; Kando, M

2018-02-13

Detections of the pulse durations and arrival timings of relativistic electron beams are important issues in accelerator physics. Electro-optic diagnostics on the Coulomb fields of electron beams have the advantages of single shot and non-destructive characteristics. We present a study of introducing the electro-optic spatial decoding technique to laser wakefield acceleration. By placing an electro-optic crystal very close to a gas target, we discovered that the Coulomb field of the electron beam possessed a spherical wavefront and was inconsistent with the previously widely used model. The field structure was demonstrated by experimental measurement, analytic calculations and simulations. A temporal mapping relationship with generality was derived in a geometry where the signals had spherical wavefronts. This study could be helpful for the applications of electro-optic diagnostics in laser plasma acceleration experiments.

Structural control of nonlinear optical absorption and refraction in dense metal nanoparticle arrays.

PubMed

Kohlgraf-Owens, Dana C; Kik, Pieter G

2009-08-17

The linear and nonlinear optical properties of a composite containing interacting spherical silver nanoparticles embedded in a dielectric host are studied as a function of interparticle separation using three dimensional frequency domain simulations. It is shown that for a fixed amount of metal, the effective third-order nonlinear susceptibility of the composite chi((3))(omega) can be significantly enhanced with respect to the linear optical properties, due to a combination of resonant surface plasmon excitation and local field redistribution. It is shown that this geometry-dependent susceptibility enhancement can lead to an improved figure of merit for nonlinear absorption. Enhancement factors for the nonlinear susceptibility of the composite are calculated, and the complex nature of the enhancement factors is discussed.

Spherical aberration of an optical system and its influence on depth of focus.

PubMed

Mikš, Antonín; Pokorný, Petr

2017-06-10

This paper analyzes the influence of spherical aberration on the depth of focus of symmetrical optical systems for imaging of axial points. A calculation of a beam's caustics is discussed using ray equations in the image plane and considering longitudinal spherical aberration as well. Concurrently, the influence of aberration coefficients on extremes of such a curve is presented. Afterwards, conditions for aberration coefficients are derived if the Strehl definition should be the same in two symmetrically placed planes with respect to the paraxial image plane. Such conditions for optical systems with large aberrations are derived with the use of geometric-optical approximation where the gyration diameter of the beam in given planes of the optical system is evaluated. Therefore, one can calculate aberration coefficients in such a way that the optical system generates a beam of rays that has the gyration radius in a given interval smaller than the defined limit value. Moreover, one can calculate the maximal depth of focus of the optical system respecting the aforementioned conditions.

Spherical aberration yielding optimum visual performance: Evaluation of intraocular lenses using adaptive optics simulation

PubMed Central

Werner, John S.; Elliott, Sarah L.; Choi, Stacey S.; Doble, Nathan

2009-01-01

PURPOSE To evaluate the influence of spherical aberration on contrast sensitivity using adaptive optics. SETTING Vision Science and Advanced Retinal Imaging Laboratory, Department of Ophthalmology & Vision Science, University of California, Davis Medical Center, Sacramento, California, USA. METHODS Contrast sensitivity at 8 cycles per degree was evaluated using an adaptive optics system that permitted aberrations to be measured with a Shack-Hartman wavefront sensor and controlled by a 109 actuator continuous-surface deformable mirror that was at a plane conjugate to the observer’s pupil. Vertical Gabor patches were viewed through a 6.3 mm diameter pupil conjugate aperture. Contrast sensitivity was measured with the deformable mirror set to produce 1 of 5 spherical aberration profiles (−0.2 to +0.2 μm). Contrast sensitivity over the range of spherical aberration was fitted with a polynomial function. RESULTS Three observers (age 21 to 24 years) participated. The measured total mean spherical aberration resulting from the spherical aberration profiles produced by the deformable mirror was between −0.15 μm and +0.25 μm. The peak contrast sensitivity of this function for the 3 observers combined occurred at +0.06 μm of spherical aberration. The peak contrast sensitivity was also achieved with positive spherical aberration for observer (mean 0.09). CONCLUSION There was intersubject variability in the measurements; however, the average visual performance was best with the introduction of a small positive spherical aberration. PMID:19545813

Analysis of scattering by a linear chain of spherical inclusions in an optical fiber

NASA Astrophysics Data System (ADS)

Chremmos, Ioannis D.; Uzunoglu, Nikolaos K.

2006-12-01

The scattering by a linear chain of spherical dielectric inclusions, embedded along the axis of an optical fiber, is analyzed using a rigorous integral equation formulation, based on the dyadic Green's function theory. The coupled electric field integral equations are solved by applying the Galerkin technique with Mie-type expansion of the field inside the spheres in terms of spherical waves. The analysis extends the previously studied case of a single spherical inhomogeneity inside a fiber to the multisphere-scattering case, by utilizing the classic translational addition theorems for spherical waves in order to analytically extract the direct-intersphere-coupling coefficients. Results for the transmitted and reflected power, on incidence of the fundamental HE11 mode, are presented for several cases.

Coherent Backscattering in the Cross-Polarized Channel

NASA Technical Reports Server (NTRS)

Mischenko, Michael I.; Mackowski, Daniel W.

2011-01-01

We analyze the asymptotic behavior of the cross-polarized enhancement factor in the framework of the standard low-packing-density theory of coherent backscattering by discrete random media composed of spherically symmetric particles. It is shown that if the particles are strongly absorbing or if the smallest optical dimension of the particulate medium (i.e., the optical thickness of a plane-parallel slab or the optical diameter of a spherically symmetric volume) approaches zero, then the cross-polarized enhancement factor tends to its upper-limit value 2. This theoretical prediction is illustrated using direct computer solutions of the Maxwell equations for spherical volumes of discrete random medium.

Local scattering stress distribution on surface of a spherical cell in optical stretcher

NASA Astrophysics Data System (ADS)

Bareil, Paul B.; Sheng, Yunlong; Chiou, Arthur

2006-12-01

We calculate stress distribution on the surface of a spherical cell trapped by two counter propagating beams in the optical stretcher in the ray optics regime. We demonstrate that the local scattering stress is perpendicular to the spherical refractive surface regardless of incident angle, polarization and the reflectance and transmittance at the surface. We explain the apparition of peaks in the stress distribution, which were not revealed in the existing theory. We consider the divergence of the incident beams from the fibers, and express the stress distribution as a function of fiber-to-cell distance. The new theory can predict the cell’s deformation more precisely.

Methods for estimating the optical constants of atmospheric hazes based on complex optical measurements

NASA Technical Reports Server (NTRS)

Zuev, V. E.; Kostin, B. S.; Naats, I. E.

1986-01-01

The methods of multifrequency laser sounding (MLS) are the most effective remote methods for investigating the atmospheric aerosols, since it is possible to obtain complete information on aerosol microstructure and the effective methods for estimating the aerosol optical constants can be developed. The MLS data interpretation consists in the solution of the set of equations containing those of laser sounding and equations for polydispersed optical characteristics. As a rule, the laser sounding equation is written in the approximation of single scattering and the equations for optical characteristics are written assuming that the atmospheric aerosol is formed by spherical and homogeneous particles. To remove the indeterminacy of equations, the method of optical sounding of atmospheric aerosol, consisting in a joint use of a mutifrequency lidar and a spectral photometer in common geometrical scheme of the optical experiment was suggested. The method is used for investigating aerosols in the cases when absorption by particles is small and indicates the minimum necessary for interpretation of a series of measurements.

Trade-offs between lens complexity and real estate utilization in a free-space multichip global interconnection module.

PubMed

Milojkovic, Predrag; Christensen, Marc P; Haney, Michael W

2006-07-01

The FAST-Net (Free-space Accelerator for Switching Terabit Networks) concept uses an array of wide-field-of-view imaging lenses to realize a high-density shuffle interconnect pattern across an array of smart-pixel integrated circuits. To simplify the optics we evaluated the efficiency gained in replacing spherical surfaces with aspherical surfaces by exploiting the large disparity between narrow vertical cavity surface emitting laser (VCSEL) beams and the wide field of view of the imaging optics. We then analyzed trade-offs between lens complexity and chip real estate utilization and determined that there exists an optimal numerical aperture for VCSELs that maximizes their area density. The results provide a general framework for the design of wide-field-of-view free-space interconnection systems that incorporate high-density VCSEL arrays.

The Individual Virtual Eye: a Computer Model for Advanced Intraocular Lens Calculation

PubMed Central

Einighammer, Jens; Oltrup, Theo; Bende, Thomas; Jean, Benedikt

2010-01-01

Purpose To describe the individual virtual eye, a computer model of a human eye with respect to its optical properties. It is based on measurements of an individual person and one of its major application is calculating intraocular lenses (IOLs) for cataract surgery. Methods The model is constructed from an eye's geometry, including axial length and topographic measurements of the anterior corneal surface. All optical components of a pseudophakic eye are modeled with computer scientific methods. A spline-based interpolation method efficiently includes data from corneal topographic measurements. The geometrical optical properties, such as the wavefront aberration, are simulated with real ray-tracing using Snell's law. Optical components can be calculated using computer scientific optimization procedures. The geometry of customized aspheric IOLs was calculated for 32 eyes and the resulting wavefront aberration was investigated. Results The more complex the calculated IOL is, the lower the residual wavefront error is. Spherical IOLs are only able to correct for the defocus, while toric IOLs also eliminate astigmatism. Spherical aberration is additionally reduced by aspheric and toric aspheric IOLs. The efficient implementation of time-critical numerical ray-tracing and optimization procedures allows for short calculation times, which may lead to a practicable method integrated in some device. Conclusions The individual virtual eye allows for simulations and calculations regarding geometrical optics for individual persons. This leads to clinical applications like IOL calculation, with the potential to overcome the limitations of those current calculation methods that are based on paraxial optics, exemplary shown by calculating customized aspheric IOLs.

A Spherical Electro Optic High Voltage Sensor

DTIC Science & Technology

1989-06-01

electro - optic (EO) crystal is introduced for photonic measurement of pulsed high-voltage fields. A spherical shape is used in order to reduce electric field gradients in the vicinity of the sensor. The sensor is pure dielectric and is interrogated remotely using a laser. The sensor does not require the connection of any conducting components, which results in the highest electrical isolation. The spherical nature of the crystal coupled with the incident laser beam, and crossed polarizers (intensity modulation scheme). automatically produces interference figures. The

Minimum change in spherical aberration that can be perceived

PubMed Central

Manzanera, Silvestre; Artal, Pablo

2016-01-01

It is important to know the visual sensitivity to optical blur from both a basic science perspective and a practical point of view. Of particular interest is the sensitivity to blur induced by spherical aberration because it is being used to increase depth of focus as a component of a presbyopic solution. Using a flicker detection-based procedure implemented on an adaptive optics visual simulator, we measured the spherical aberration thresholds that produce just-noticeable differences in perceived image quality. The thresholds were measured for positive and negative values of spherical aberration, for best focus and + 0.5 D and + 1.0 D of defocus. At best focus, the SA thresholds were 0.20 ± 0.01 µm and −0.17 ± 0.03 µm for positive and negative spherical aberration respectively (referred to a 6-mm pupil). These experimental values may be useful in setting spherical aberration permissible levels in different ophthalmic techniques. PMID:27699113

A modular assembling platform for manufacturing of microsystems by optical tweezers

NASA Astrophysics Data System (ADS)

Ksouri, Sarah Isabelle; Aumann, Andreas; Ghadiri, Reza; Prüfer, Michael; Baer, Sebastian; Ostendorf, Andreas

2013-09-01

Due to the increased complexity in terms of materials and geometries for microsystems new assembling techniques are required. Assembling techniques from the semiconductor industry are often very specific and cannot fulfill all specifications in more complex microsystems. Therefore, holographic optical tweezers are applied to manipulate structures in micrometer range with highest flexibility and precision. As is well known non-spherical assemblies can be trapped and controlled by laser light and assembled with an additional light modulator application, where the incident laser beam is rearranged into flexible light patterns in order to generate multiple spots. The complementary building blocks are generated by a two-photon-polymerization process. The possibilities of manufacturing arbitrary microstructures and the potential of optical tweezers lead to the idea of combining manufacturing techniques with manipulation processes to "microrobotic" processes. This work presents the manipulation of generated complex microstructures with optical tools as well as a storage solution for 2PP assemblies. A sample holder has been developed for the manual feeding of 2PP building blocks. Furthermore, a modular assembling platform has been constructed for an `all-in-one' 2PP manufacturing process as a dedicated storage system. The long-term objective is the automation process of feeding and storage of several different 2PP micro-assemblies to realize an automated assembly process.

In vitro comparative optical bench analysis of a spherical and aspheric optic design of the same IOL model.

PubMed

Tandogan, Tamer; Auffarth, Gerd U; Choi, Chul Y; Liebing, Stephanie; Mayer, Christian; Khoramnia, Ramin

2017-02-08

To analyse objective optical properties of the spherical and aspheric design of the same intraocular lens (IOL) model using optical bench analysis. This study entailed a comparative analysis of 10 spherical C-flex 570 C and 10 aspheric C-flex 970 C IOLs (Rayner Intraocular Lenses Ltd., Hove, UK) of 26 diopters [D] using an optical bench (OptiSpheric, Trioptics, Germany). In all lenses, we evaluated the modulation transfer function (MTF) at 50 lp/mm and 100 lp/mm and the Strehl Ratio using a 3-mm (photopic) and 4.5-mm (mesopic) aperture. At 50 lp/mm, the MTF values were 0.713/0.805 (C-flex 570 C/C-flex 970 C) for a 3-mm aperture and 0.294/0.591 for a 4.5-mm aperture. At 100 lp/mm, the MTF values were 0.524/0.634 for a 3-mm aperture and 0.198/0.344 for a 4.5-mm aperture. The Strehl Ratio was 0.806/0.925 and 0.237/0.479 for a 3-mm and 4.5-mm aperture respectively. A Mann-Whitney U test revealed all intergroup differences to be statistically significant (p < 0.01). The aspheric IOL design achieved higher MTF values than the spherical design of the same IOL for both apertures. Moreover, the differences between the two designs of the IOL were more prominent for larger apertures. This suggests that the evaluated IOL provides enhanced optical quality to patients with larger pupils or working under mesopic conditions.

Resolving the Southern African Large Telescope's image quality problems

NASA Astrophysics Data System (ADS)

O'Donoghue, Darragh E.; Crause, Lisa A.; O'Connor, James; Strümpfer, Francois; Strydom, Ockert J.; Sass, Craig; Brink, Janus D.; Plessis, Charl du; Wiid, Eben; Love, Jonathan

2013-08-01

Images obtained with the Southern African Large Telescope (SALT) during its commissioning phase in 2006 showed degradation due to a large focus gradient, astigmatism, and higher order optical aberrations. An extensive forensic investigation exonerated the primary mirror and the science instruments before pointing to the mechanical interface between the telescope and the spherical aberration corrector, the complex optical subassembly which corrects the spherical aberration introduced by the 11-m primary mirror. Having diagnosed the problem, a detailed repair plan was formulated and implemented when the corrector was removed from the telescope in April 2009. The problematic interface was replaced, and the four aspheric mirrors were optically tested and re-aligned. Individual mirror surface figures were confirmed to meet specification, and a full system test after the re-alignment yielded a root mean square wavefront error of 0.15 waves. The corrector was reinstalled in August 2010 and aligned with respect to the payload and primary mirror. Subsequent on-sky tests revealed spurious signals being sent to the tracker by the auto-collimator, the instrument that maintains the alignment of the corrector with respect to the primary mirror. After rectifying this minor issue, the telescope yielded uniform 1.1 arcsec star images over the full 10-arcmin field of view.

Excitation of multipolar surface plasmon resonance in plasmonic nanoparticles by complex accelerating beams

NASA Astrophysics Data System (ADS)

Yang, Yang; Li, Jiafang; Li, Zhi-Yuan; Chen, Yue-Gang

2015-07-01

In this paper, through a vector-spherical harmonics approach, we investigate the optical spectra of plasmonic Au nanoparticles excited by two special accelerating beams: a non-paraxial Airy beam and a Bessel beam. We systematically analyze the impacts of the beam profile, phase, and helical wave front of the electromagnetic fields on the optical spectrum and the excitation of the surface plasmon resonance (SPR). We find that the high-order phase in the Airy beam would result in strong plasmonic oscillations in the optical spectra, while the cone angle and orbital angular momentum carried by the Bessel beam could be employed to engineer the plasmon modes excited in Au nanoparticles. Furthermore, the optical spectrum excited by a combined Airy-Bessel-Gauss beam is discussed. The study could help to deeply explore new ways to manipulate SPR in metal nanoparticles via the wave front engineering of optical beams for enhancing light-matter interaction and optical sensing performance.

Electromagnetic Scattering by Spheroidal Volumes of Discrete Random Medium

NASA Technical Reports Server (NTRS)

Dlugach, Janna M.; Mishchenko, Michael I.

2017-01-01

We use the superposition T-matrix method to compare the far-field scattering matrices generated by spheroidal and spherical volumes of discrete random medium having the same volume and populated by identical spherical particles. Our results fully confirm the robustness of the previously identified coherent and diffuse scattering regimes and associated optical phenomena exhibited by spherical particulate volumes and support their explanation in terms of the interference phenomenon coupled with the order-of-scattering expansion of the far-field Foldy equations. We also show that increasing non-sphericity of particulate volumes causes discernible (albeit less pronounced) optical effects in forward and backscattering directions and explain them in terms of the same interference/multiple-scattering phenomenon.

Spin angular momentum transfer from TEM00 focused Gaussian beams to negative refractive index spherical particles

PubMed Central

Ambrosio, Leonardo A.; Hernández-Figueroa, Hugo E.

2011-01-01

We investigate optical torques over absorbent negative refractive index spherical scatterers under the influence of linear and circularly polarized TEM00 focused Gaussian beams, in the framework of the generalized Lorenz-Mie theory with the integral localized approximation. The fundamental differences between optical torques due to spin angular momentum transfer in positive and negative refractive index optical trapping are outlined, revealing the effect of the Mie scattering coefficients in one of the most fundamental properties in optical trapping systems. PMID:21833372

Impact of contact lens zone geometry and ocular optics on bifocal retinal image quality

PubMed Central

Bradley, Arthur; Nam, Jayoung; Xu, Renfeng; Harman, Leslie; Thibos, Larry

2014-01-01

Purpose To examine the separate and combined influences of zone geometry, pupil size, diffraction, apodisation and spherical aberration on the optical performance of concentric zonal bifocals. Methods Zonal bifocal pupil functions representing eye + ophthalmic correction were defined by interleaving wavefronts from separate optical zones of the bifocal. A two-zone design (a central circular inner zone surrounded by an annular outer-zone which is bounded by the pupil) and a five-zone design (a central small circular zone surrounded by four concentric annuli) were configured with programmable zone geometry, wavefront phase and pupil transmission characteristics. Using computational methods, we examined the effects of diffraction, Stiles Crawford apodisation, pupil size and spherical aberration on optical transfer functions for different target distances. Results Apodisation alters the relative weighting of each zone, and thus the balance of near and distance optical quality. When spherical aberration is included, the effective distance correction, add power and image quality depend on zone-geometry and Stiles Crawford Effect apodisation. When the outer zone width is narrow, diffraction limits the available image contrast when focused, but as pupil dilates and outer zone width increases, aberrations will limit the best achievable image quality. With two-zone designs, balancing near and distance image quality is not achieved with equal area inner and outer zones. With significant levels of spherical aberration, multi-zone designs effectively become multifocals. Conclusion Wave optics and pupil varying ocular optics significantly affect the imaging capabilities of different optical zones of concentric bifocals. With two-zone bifocal designs, diffraction, pupil apodisation spherical aberration, and zone size influence both the effective add power and the pupil size required to balance near and distance image quality. Five-zone bifocal designs achieve a high degree of pupil size independence, and thus will provide more consistent performance as pupil size varies with light level and convergence amplitude. PMID:24588552

Estimation of settling velocity of sediment particles in estuarine and coastal waters

NASA Astrophysics Data System (ADS)

Nasiha, Hussain J.; Shanmugam, Palanisamy

2018-04-01

A model for estimating the settling velocity of sediment particles (spherical and non-spherical) in estuarine and coastal waters is developed and validated using experimental data. The model combines the physical, optical and hydrodynamic properties of the particles and medium to estimate the sediment settling velocity. The well-known Stokes law is broadened to account for the influencing factors of settling velocity such as particle size, shape and density. To derive the model parameters, laboratory experiments were conducted using natural flaky seashells, spherical beach sands and ball-milled seashell powders. Spectral light backscattering measurements of settling particles in a water tank were made showing a distinct optical feature with a peak shifting from 470-490 nm to 500-520 nm for particle populations from spherical to flaky grains. This significant optical feature was used as a proxy to make a shape determination in the present model. Other parameters experimentally determined included specific gravity (ΔSG) , Corey shape factor (CSF) , median grain diameter (D50) , drag coefficient (Cd) and Reynolds number (Re) . The CSF values considered ranged from 0.2 for flaky to 1.0 for perfectly spherical grains and Reynolds numbers from 2.0 to 105 for the laminar to turbulent flow regimes. The specific gravity of submerged particles was optically derived and used along with these parameters to estimate the sediment settling velocity. Comparison with the experiment data showed that the present model estimated settling velocities of spherical and non-spherical particles that were closely consistent with the measured values. Findings revealed that for a given D50, the flaky particles caused a greater decrease in settling velocity than the spherical particles which suggests that the particle shape factor has a profound role in influencing the sediment settling velocity and drag coefficients, especially in transitional and turbulent flow regimes. The present model can be easily adopted for various scientific and operational applications since the required parameters are readily measurable with the commercially available instrumentations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Suvam; Naghma, Rahla; Kaur, Jaspreet

The total and ionization cross sections for electron scattering by benzene, halobenzenes, toluene, aniline, and phenol are reported over a wide energy domain. The multi-scattering centre spherical complex optical potential method has been employed to find the total elastic and inelastic cross sections. The total ionization cross section is estimated from total inelastic cross section using the complex scattering potential-ionization contribution method. In the present article, the first theoretical calculations for electron impact total and ionization cross section have been performed for most of the targets having numerous practical applications. A reasonable agreement is obtained compared to existing experimental observationsmore » for all the targets reported here, especially for the total cross section.« less

[The eye, the optic system and its anomalies].

PubMed

Cohen, S Y

1993-09-15

The eye is a perceptive system with extremely complex physiology, although its optical properties can be assimilated to those of spherical diopters. Various approximations make it possible to reduce the eyeball to a single convex diopter. With a normal eye the image of an object situated ad infinitum focuses on the retina. The normal eye is called emmetropic. Otherwise, the eye is called ametropic. Several types of ametropy exist. When the image focuses in front of the retina the eye is said to be myopic. When the image focuses behind the retina the eye is called hypermetropic (or hyperopic). When the image of an object differs according to various focusing axes, the eye is said to be astigmatic.

Analysis of a dual-reflector antenna system using physical optics and digital computers

NASA Technical Reports Server (NTRS)

Schmidt, R. F.

1972-01-01

The application of physical-optics diffraction theory to a deployable dual-reflector geometry is discussed. The methods employed are not restricted to the Conical-Gregorian antenna, but apply in a general way to dual and even multiple reflector systems. Complex vector wave methods are used in the Fresnel and Fraunhofer regions of the reflectors. Field amplitude, phase, polarization data, and time average Poynting vectors are obtained via an IBM 360/91 digital computer. Focal region characteristics are plotted with the aid of a CalComp plotter. Comparison between the GSFC Huygens wavelet approach, JPL measurements, and JPL computer results based on the near field spherical wave expansion method are made wherever possible.

Thomas Young's investigations in gradient-index optics.

PubMed

Atchison, David A; Charman, W Neil

2011-05-01

James Clerk Maxwell is usually recognized as being the first, in 1854, to consider using inhomogeneous media in optical systems. However, some 50 years earlier, Thomas Young, stimulated by his interest in the optics of the eye and accommodation, had already modeled some applications of gradient-index optics. These applications included using an axial gradient to provide spherical aberration-free optics and a spherical gradient to describe the optics of the atmosphere and the eye lens. We evaluated Young's contributions. We attempted to derive Young's equations for axial and spherical refractive index gradients. Raytracing was used to confirm accuracy of formula. We did not confirm Young's equation for the axial gradient to provide aberration-free optics but derived a slightly different equation. We confirmed the correctness of his equations for deviation of rays in a spherical gradient index and for the focal length of a lens with a nucleus of fixed index surrounded by a cortex of reducing index toward the edge. Young claimed that the equation for focal length applied to a lens with part of the constant index nucleus of the sphere removed, such that the loss of focal length was a quarter of the thickness removed, but this is not strictly correct. Young's theoretical work in gradient-index optics received no acknowledgment from either his contemporaries or later authors. Although his model of the eye lens is not an accurate physiological description of the human lens, with the index reducing least quickly at the edge, it represented a bold attempt to approximate the characteristics of the lens. Thomas Young's work deserves wider recognition.

Asymmetric Spherical Coupled Escape Probability: Model and Results for Optically Thick Cometary Comae

NASA Astrophysics Data System (ADS)

Gersch, Alan; A'Hearn, M. F.

2012-05-01

We have adapted the Coupled Escape Probability method of radiative transfer calculations for use in asymmetrical spherical situations and applied it to modeling molecular emission spectra of potentially optically thick cometary comae. Recent space missions (e.g. Deep Impact & EPOXI) have provided spectra from comets of unprecedented spatial resolution of the regions of the coma near the nucleus, where the coma may be optically thick. Currently active missions (e.g. Rosetta) and hopefully more in the future will continue the trend and demonstrate the need for better modeling of comae with optical depth effects included. Here we present a brief description of our model and results of interest for cometary studies, especially for space based observations. Although primarily motivated by the need for comet modeling, our (asymmetric spherical) radiative transfer model could be used for studying other astrophysical phenomena as well.

Low-cost method for producing extreme ultraviolet lithography optics

DOEpatents

Folta, James A [Livermore, CA; Montcalm, Claude [Fort Collins, CO; Taylor, John S [Livermore, CA; Spiller, Eberhard A [Mt. Kisco, NY

2003-11-21

Spherical and non-spherical optical elements produced by standard optical figuring and polishing techniques are extremely expensive. Such surfaces can be cheaply produced by diamond turning; however, the roughness in the diamond turned surface prevent their use for EUV lithography. These ripples are smoothed with a coating of polyimide before applying a 60 period Mo/Si multilayer to reflect a wavelength of 134 .ANG. and have obtained peak reflectivities close to 63%. The savings in cost are about a factor of 100.

Cartilage microindentation using cylindrical and spherical optical fiber indenters with integrated Bragg gratings as force sensors

NASA Astrophysics Data System (ADS)

Marchi, G.; Canti, O.; Baier, V.; Micallef, W.; Hartmann, B.; Alberton, P.; Aszodi, A.; Clausen-Schaumann, H.; Roths, J.

2018-02-01

Fiber optic microindentation sensors that have the potential to be integrated into arthroscopic instruments and to allow localizing degraded articular cartilage are presented in this paper. The indenters consist of optical fibers with integrated Bragg gratings as force sensors. In a basic configuration, the tip of the fiber optic indenter consists of a cleaved fiber end, forming a cylindrical flat punch indenter geometry. When using this indenter geometry, high stresses at the edges of the cylinder are present, which can disrupt the tissue structure. This is avoided with an improved version of the indenter. A spherical indenter tip that is formed by melting the end of the glass fiber. The spherical fiber tip shows the additional advantage of strongly reducing reflections from the fiber end. This allows a reduction of the length of the fiber optic sensor element from 65 mm of the flat punch type to 27 mm of the spherical punch. In order to compare the performance of both indenter types, in vitro stress-relaxation indentation experiments were performed on bovine articular cartilage with both indenter types, to assess biomechanical properties of bovine articular cartilage. For indentation depths between 60 μm and 300 μm, the measurements with both indenter types agreed very well with each other. This shows that both indenter geometries are suitable for microindentation measuremnts . The spherical indenter however has the additional advantage that it minimizes the risk to damage the surface of the tissue and has less than half dimensions than the flat indenter.

Tailoring the chirality of light emission with spherical Si-based antennas.

PubMed

Zambrana-Puyalto, Xavier; Bonod, Nicolas

2016-05-21

Chirality of light is of fundamental importance in several enabling technologies with growing applications in life sciences, chemistry and photodetection. Recently, some attention has been focused on chiral quantum emitters. Consequently, optical antennas which are able to tailor the chirality of light emission are needed. Spherical nanoresonators such as colloids are of particular interest to design optical antennas since they can be synthesized at a large scale and they exhibit good optical properties. Here, we show that these colloids can be used to tailor the chirality of a chiral emitter. To this purpose, we derive an analytic formalism to model the interaction between a chiral emitter and a spherical resonator. We then compare the performances of metallic and dielectric spherical antennas to tailor the chirality of light emission. It is seen that, due to their strong electric dipolar response, metallic spherical nanoparticles spoil the chirality of light emission by yielding achiral fields. In contrast, thanks to the combined excitation of electric and magnetic modes, dielectric Si-based particles feature the ability to inhibit or to boost the chirality of light emission. Finally, it is shown that dual modes in dielectric antennas preserve the chirality of light emission.

Loss of laminin alpha 1 results in multiple structural defects and divergent effects on adhesion during vertebrate optic cup morphogenesis

PubMed Central

Bryan, Chase D.; Chien, Chi-Bin; Kwan, Kristen M.

2016-01-01

The vertebrate eye forms via a complex set of morphogenetic events. The optic vesicle evaginates and undergoes transformative shape changes to form the optic cup, in which neural retina and retinal pigmented epithelium enwrap the lens. It has long been known that a complex, glycoprotein-rich extracellular matrix layer surrounds the developing optic cup throughout the process, yet the functions of the matrix and its specific molecular components have remained unclear. Previous work established a role for laminin extracellular matrix in particular steps of eye development, including optic vesicle evagination, lens differentiation, and retinal ganglion cell polarization, yet it is unknown what role laminin might play in the early process of optic cup formation subsequent to the initial step of optic vesicle evagination. Here, we use the zebrafish lama1 mutant (lama1UW1) to determine the function of laminin during optic cup morphogenesis. Using live imaging, we find, surprisingly, that loss of laminin leads to divergent effects on focal adhesion assembly in a spatiotemporally-specific manner, and that laminin is required for multiple steps of optic cup morphogenesis, including optic stalk constriction, invagination, and formation of a spherical lens. Laminin is not required for single cell behaviors and changes in cell shape. Rather, in lama1UW1 mutants, loss of epithelial polarity and altered adhesion lead to defective tissue architecture and formation of a disorganized retina. These results demonstrate that the laminin extracellular matrix plays multiple critical roles regulating adhesion and polarity to establish and maintain tissue structure during optic cup morphogenesis. PMID:27339294

Numerical simulation of the trajectory of a light ray propagating through an optic system with non-centered spherical diopters and broken optic axis

NASA Astrophysics Data System (ADS)

Bacescu, D.; Ivanov, I.

2006-03-01

The present paper is devoted to the elaboration of a strategy for the design of some practical focusing devices for the radiation emitted by a high-power laser used in thermal treatment processes. Usually, technological solutions employ spherical mirrors. Because spherical mirrors introduce a certain astigmatism, it is necessary to get an energetically efficient configuration which reduces as much as possible the astigmatic difference, thus concentrating the laser radiation energy which is distributed within the area between the sagital and meridional foci.

Upper limit set for level of lightning activity on Titan

NASA Technical Reports Server (NTRS)

Desch, M. D.; Kaiser, M. L.

1990-01-01

Because optically thick cloud and haze layers prevent lightning detection at optical wavelength on Titan, a search was conducted for lightning-radiated signals (spherics) at radio wavelengths using the planetary radioastronomy instrument aboard Voyager 1. Given the maximum ionosphere density of about 3000/cu cm, lightning spherics should be detectable above an observing frequency of 500 kHz. Since no evidence for spherics is found, an upper limit to the total energy per flash in Titan lightning of about 10 to the 6th J, or about 1000 times weaker than that of typical terrestrial lightning, is inferred.

Refractive Changes Induced by Spherical Aberration in Laser Correction Procedures: An Adaptive Optics Study.

PubMed

Amigó, Alfredo; Martinez-Sorribes, Paula; Recuerda, Margarita

2017-07-01

To study the effect on vision of induced negative and positive spherical aberration within the range of laser vision correction procedures. In 10 eyes (mean age: 35.8 years) under cyclopegic conditions, spherical aberration values from -0.75 to +0.75 µm in 0.25-µm steps were induced by an adaptive optics system. Astigmatism and spherical refraction were corrected, whereas the other natural aberrations remained untouched. Visual acuity, depth of focus defined as the interval of vision for which the target was still perceived acceptable, contrast sensitivity, and change in spherical refraction associated with the variation in pupil diameter from 6 to 2.5 mm were measured. A refractive change of 1.60 D/µm of induced spherical aberration was obtained. Emmetropic eyes became myopic when positive spherical aberration was induced and hyperopic when negative spherical aberration was induced (R 2 = 81%). There were weak correlations between spherical aberration and visual acuity or depth of focus (R 2 = 2% and 3%, respectively). Contrast sensitivity worsened with the increment of spherical aberration (R 2 = 59%). When pupil size decreased, emmetropic eyes became hyperopic when preexisting spherical aberration was positive and myopic when spherical aberration was negative, with an average refractive change of 0.60 D/µm of spherical aberration (R 2 = 54%). An inverse linear correlation exists between the refractive state of the eye and spherical aberration induced within the range of laser vision correction. Small values of spherical aberration do not worsen visual acuity or depth of focus, but positive spherical aberration may induce night myopia. In addition, the changes in spherical refraction when the pupil constricts may worsen near vision when positive spherical aberration is induced or improve it when spherical aberration is negative. [J Refract Surg. 2017;33(7):470-474.]. Copyright 2017, SLACK Incorporated.

Development and application of a ray-based model of light propagation through a spherical acousto-optic lens

PubMed Central

Evans, Geoffrey J.; Kirkby, Paul A.; Nadella, K. M. Naga Srinivas; Marin, Bóris; Silver, R. Angus

2016-01-01

A spherical acousto-optic lens (AOL) consists of four acousto-optic deflectors (AODs) that can rapidly and precisely control the focal position of an optical beam in 3D space. Development and application of AOLs has increased the speed at which 3D random access point measurements can be performed with a two-photon microscope. This has been particularly useful for measuring brain activity with fluorescent reporter dyes because neuronal signalling is rapid and sparsely distributed in 3D space. However, a theoretical description of light propagation through AOLs has lagged behind their development, resulting in only a handful of simplified principles to guide AOL design and optimization. To address this we have developed a ray-based computer model of an AOL incorporating acousto-optic diffraction and refraction by anisotropic media. We extended an existing model of a single AOD with constant drive frequency to model a spherical AOL: four AODs in series driven with linear chirps. AOL model predictions of the relationship between optical transmission efficiency and acoustic drive frequency including second order diffraction effects closely matched experimental measurements from a 3D two-photon AOL microscope. Moreover, exploration of different AOL drive configurations identified a new simple rule for maximizing the field of view of our compact AOL design. By providing a theoretical basis for understanding optical transmission through spherical AOLs, our open source model is likely to be useful for comparing and improving different AOL designs, as well as identifying the acoustic drive configurations that provide the best transmission performance over the 3D focal region. PMID:26368449

Development and application of a ray-based model of light propagation through a spherical acousto-optic lens.

PubMed

Evans, Geoffrey J; Kirkby, Paul A; Naga Srinivas Nadella, K M; Marin, Bóris; Angus Silver, R

2015-09-07

A spherical acousto-optic lens (AOL) consists of four acousto-optic deflectors (AODs) that can rapidly and precisely control the focal position of an optical beam in 3D space. Development and application of AOLs has increased the speed at which 3D random access point measurements can be performed with a two-photon microscope. This has been particularly useful for measuring brain activity with fluorescent reporter dyes because neuronal signalling is rapid and sparsely distributed in 3D space. However, a theoretical description of light propagation through AOLs has lagged behind their development, resulting in only a handful of simplified principles to guide AOL design and optimization. To address this we have developed a ray-based computer model of an AOL incorporating acousto-optic diffraction and refraction by anisotropic media. We extended an existing model of a single AOD with constant drive frequency to model a spherical AOL: four AODs in series driven with linear chirps. AOL model predictions of the relationship between optical transmission efficiency and acoustic drive frequency including second order diffraction effects closely matched experimental measurements from a 3D two-photon AOL microscope. Moreover, exploration of different AOL drive configurations identified a new simple rule for maximizing the field of view of our compact AOL design. By providing a theoretical basis for understanding optical transmission through spherical AOLs, our open source model is likely to be useful for comparing and improving different AOL designs, as well as identifying the acoustic drive configurations that provide the best transmission performance over the 3D focal region.

Research on Measurement Accuracy of Laser Tracking System Based on Spherical Mirror with Rotation Errors of Gimbal Mount Axes

NASA Astrophysics Data System (ADS)

Shi, Zhaoyao; Song, Huixu; Chen, Hongfang; Sun, Yanqiang

2018-02-01

This paper presents a novel experimental approach for confirming that spherical mirror of a laser tracking system can reduce the influences of rotation errors of gimbal mount axes on the measurement accuracy. By simplifying the optical system model of laser tracking system based on spherical mirror, we can easily extract the laser ranging measurement error caused by rotation errors of gimbal mount axes with the positions of spherical mirror, biconvex lens, cat's eye reflector, and measuring beam. The motions of polarization beam splitter and biconvex lens along the optical axis and vertical direction of optical axis are driven by error motions of gimbal mount axes. In order to simplify the experimental process, the motion of biconvex lens is substituted by the motion of spherical mirror according to the principle of relative motion. The laser ranging measurement error caused by the rotation errors of gimbal mount axes could be recorded in the readings of laser interferometer. The experimental results showed that the laser ranging measurement error caused by rotation errors was less than 0.1 μm if radial error motion and axial error motion were within ±10 μm. The experimental method simplified the experimental procedure and the spherical mirror could reduce the influences of rotation errors of gimbal mount axes on the measurement accuracy of the laser tracking system.

Monitoring of photoluminescence decay by alkali and alkaline earth metal cations using a photoluminescent bolaamphiphile self-assembly as an optical probe.

PubMed

Kim, Sunhyung; Kwak, Jinyoung; Lee, Sang-Yup

2014-05-01

Photoluminescence (PL) decay induced by the displacement of an ionic fluorescence component, Tb(3+), with alkali and alkaline earth metal cations was investigated using photoluminescent spherical self-assemblies as optical probes. The photoluminescent spherical self-assembly was prepared by the self-organization of a tyrosine-containing bolaamphiphile molecule with a photosensitizer and Tb(3+) ion. The lanthanide ion, Tb(3+), electrically bound to the carboxyl group of the bolaamphiphile molecule, was displaced by alkali and alkaline earth metal cations that had stronger electrophilicity. The PL of the self-assembly decayed remarkably due to the substitution of lanthanide ions with alkali and alkaline earth metal cations. The PL decay showed a positive correlation with cation concentration and was sensitive to the cation valency. Generally, the PL decay was enhanced by the electrophilicity of the cations. However, Ca(2+) showed greater PL decay than Mg(2+) because Ca(2+) could create various complexes with the carboxyl groups of the bolaamphiphile molecule. Microscopic and spectroscopic investigations were conducted to study the photon energy transfer and displacement of Tb(3+) by the cation exchange. This study demonstrated that the PL decay by the displacement of the ionic fluorescent compound was applied to the detection of various cations in aqueous media and is applicable to the development of future optical sensors. Copyright © 2014 Elsevier B.V. All rights reserved.

Electron impact ionisation cross section for organoplatinum compounds

NASA Astrophysics Data System (ADS)

Mahato, Dibyendu; Naghma, Rahla; Alam, Mohammad Jane; Ahmad, Shabbir; Antony, Bobby

2016-11-01

This article reports electron impact ionisation cross sections for platinum-based drugs viz., cisplatin (H6N2Cl2Pt), carboplatin (C6H12N2O4Pt), oxaliplatin (C8H14N2O4Pt), nedaplatin (C2H8N2O3Pt) and satraplatin (C10H22ClN2O4Pt) complexes used in the cancer chemotherapy. The multi-scattering centre spherical complex optical potential formalism is used to obtain the inelastic cross section for these large molecules upon electron impact. The ionisation cross section is derived from the inelastic cross section employing complex scattering potential-ionisation contribution method. Comparison is made with previous results, where ever available and overall a reasonable agreement is observed. This is the first attempt to report total ionisation cross sections for nedaplatin and satraplatin complexes.

Hybrid RF / Optical Communication Terminal with Spherical Primary Optics for Optical Reception

NASA Technical Reports Server (NTRS)

Charles, Jeffrey R.; Hoppe, Daniel H.; Sehic, Asim

2011-01-01

Future deep space communications are likely to employ not only the existing RF uplink and downlink, but also a high capacity optical downlink. The Jet Propulsion Laboratory (JPL) is currently investigating the benefits of a ground based hybrid RF and deep space optical terminal based on limited modification of existing 34 meter antenna designs. The ideal design would include as large an optical aperture as technically practical and cost effective, cause minimal impact to RF performance, and remain cost effective even when compared to a separate optical terminal of comparable size. Numerous trades and architectures have been considered, including shared RF and optical apertures having aspheric optics and means to separate RF and optical signals, plus, partitioned apertures in which various zones of the primary are dedicated to optical reception. A design based on the latter is emphasized in this paper, employing spherical primary optics and a new version of a "clamshell" corrector that is optimized to fit within the limited space between the antenna sub-reflector and the existing apex structure that supports the subreflector. The mechanical design of the hybrid accommodates multiple spherical primary mirror panels in the central 11 meters of the antenna, and integrates the clamshell corrector and optical receiver modules with antenna hardware using existing attach points to the maximum extent practical. When an optical collection area is implemented on a new antenna, it is possible to design the antenna structure to accommodate the additional weight of optical mirrors providing an equivalent aperture of several meters diameter. The focus of our near term effort is to use optics with the 34 meter DSS-13 antenna at Goldstone to demonstrate spatial optical acquisition and tracking capability using an optical system that is temporarily integrated into the antenna.

Resonant inelastic scattering by use of geometrical optics.

PubMed

Schulte, Jörg; Schweiger, Gustav

2003-02-01

We investigate the inelastic scattering on spherical particles that contain one concentric inclusion in the case of input and output resonances, using a geometrical optics method. The excitation of resonances is included in geometrical optics by use of the concept of tunneled rays. To get a quantitative description of optical tunneling on spherical surfaces, we derive appropriate Fresnel-type reflection and transmission coefficients for the tunneled rays. We calculate the inelastic scattering cross section in the case of input and output resonances and investigate the influence of the distribution of the active material in the particle as well as the influence of the inclusion on inelastic scattering.

The study of optimization on process parameters of high-accuracy computerized numerical control polishing

NASA Astrophysics Data System (ADS)

Huang, Wei-Ren; Huang, Shih-Pu; Tsai, Tsung-Yueh; Lin, Yi-Jyun; Yu, Zong-Ru; Kuo, Ching-Hsiang; Hsu, Wei-Yao; Young, Hong-Tsu

2017-09-01

Spherical lenses lead to forming spherical aberration and reduced optical performance. Consequently, in practice optical system shall apply a combination of spherical lenses for aberration correction. Thus, the volume of the optical system increased. In modern optical systems, aspherical lenses have been widely used because of their high optical performance with less optical components. However, aspherical surfaces cannot be fabricated by traditional full aperture polishing process due to their varying curvature. Sub-aperture computer numerical control (CNC) polishing is adopted for aspherical surface fabrication in recent years. By using CNC polishing process, mid-spatial frequency (MSF) error is normally accompanied during this process. And the MSF surface texture of optics decreases the optical performance for high precision optical system, especially for short-wavelength applications. Based on a bonnet polishing CNC machine, this study focuses on the relationship between MSF surface texture and CNC polishing parameters, which include feed rate, head speed, track spacing and path direction. The power spectral density (PSD) analysis is used to judge the MSF level caused by those polishing parameters. The test results show that controlling the removal depth of single polishing path, through the feed rate, and without same direction polishing path for higher total removal depth can efficiently reduce the MSF error. To verify the optical polishing parameters, we divided a correction polishing process to several polishing runs with different direction polishing paths. Compare to one shot polishing run, multi-direction path polishing plan could produce better surface quality on the optics.

Electron impact scattering study of hypohalous acids HOX (X = F, Cl, Br, I)

NASA Astrophysics Data System (ADS)

Yadav, Hitesh; Bhutadia, Harshad; Prajapati, Dinesh; Desai, Hardik; Vinodkumar, Minaxi; Vinodkumar, P. C.

2018-05-01

In this article we aim to report total cross sections (TCS) QT, total elastic cross sections (Qel), total inelastic cross sections (Qinel) i.e. (total ionizations cross sections (Qion)+total electronic excitation cross sections (Qexc)) from threshold of the target to 5000 eV energy range. We have used a well-defined theoretical methodology Spherical Complex Optical Potential (SCOP) to compute QT, Qel and Qinel and Complex Scattering Potential - ionization contribution (CSP - ic) method to report the (Qion). The cross-sectional data reported here for the Hypohalous Acids is for the first time and the present data can become a guideline for the experimentalist to study these targets.

Magneto-optical absorption in semiconducting spherical quantum dots: Influence of the dot-size, confining potential, and magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kushwaha, Manvir S.

2014-12-15

Semiconducting quantum dots – more fancifully dubbed artificial atoms – are quasi-zero dimensional, tiny, man-made systems with charge carriers completely confined in all three dimensions. The scientific quest behind the synthesis of quantum dots is to create and control future electronic and optical nanostructures engineered through tailoring size, shape, and composition. The complete confinement – or the lack of any degree of freedom for the electrons (and/or holes) – in quantum dots limits the exploration of spatially localized elementary excitations such as plasmons to direct rather than reciprocal space. Here we embark on a thorough investigation of the magneto-optical absorptionmore » in semiconducting spherical quantum dots characterized by a confining harmonic potential and an applied magnetic field in the symmetric gauge. This is done within the framework of Bohm-Pines’ random-phase approximation that enables us to derive and discuss the full Dyson equation that takes proper account of the Coulomb interactions. As an application of our theoretical strategy, we compute various single-particle and many-particle phenomena such as the Fock-Darwin spectrum; Fermi energy; magneto-optical transitions; probability distribution; and the magneto-optical absorption in the quantum dots. It is observed that the role of an applied magnetic field on the absorption spectrum is comparable to that of a confining potential. Increasing (decreasing) the strength of the magnetic field or the confining potential is found to be analogous to shrinking (expanding) the size of the quantum dots: resulting into a blue (red) shift in the absorption spectrum. The Fermi energy diminishes with both increasing magnetic-field and dot-size; and exhibits saw-tooth-like oscillations at large values of field or dot-size. Unlike laterally confined quantum dots, both (upper and lower) magneto-optical transitions survive even in the extreme instances. However, the intra-Landau level transitions are seen to be forbidden. The spherical quantum dots have an edge over the strictly two-dimensional quantum dots in that the additional (magnetic) quantum number makes the physics richer (but complex). A deeper grasp of the Coulomb blockade, quantum coherence, and entanglement can lead to a better insight into promising applications involving lasers, detectors, storage devices, and quantum computing.« less

Excitation energy transfer in molecular complexes: transport processes, optical properties and effects of nearby placed metal nano-particles

NASA Astrophysics Data System (ADS)

May, Volkhard; Megow, Jörg; Zelinskyi, Iaroslav

2012-04-01

Excitation energy transfer (EET) in molecular systems is studied theoretically. Chromophore complexes are considered which are formed by a butanediamine dendrimer with four pheophorbide-a molecules. To achieve a description with an atomic resolution and to account for the effect of an ethanol solvent a mixed quantum classical methodology is utilized. Details of the EET and spectra of transient anisotropy showing signatures of EET are presented. A particular control of intermolecular EET is achieved by surface plasmons of nearby placed metal nanoparticles (MNP). To attain a quantum description of the molecule-MNP system a microscopic theory is introduced. As a particular application surface plasmon affected absorption spectra of molecular complexes placed in the proximity of a spherical MNP are discussed.

Ternary mixed crystal effects on interface optical phonon and electron-phonon coupling in zinc-blende GaN/AlxGa1-xN spherical quantum dots

NASA Astrophysics Data System (ADS)

Huang, Wen Deng; Chen, Guang De; Yuan, Zhao Lin; Yang, Chuang Hua; Ye, Hong Gang; Wu, Ye Long

2016-02-01

The theoretical investigations of the interface optical phonons, electron-phonon couplings and its ternary mixed effects in zinc-blende spherical quantum dots are obtained by using the dielectric continuum model and modified random-element isodisplacement model. The features of dispersion curves, electron-phonon coupling strengths, and its ternary mixed effects for interface optical phonons in a single zinc-blende GaN/AlxGa1-xN spherical quantum dot are calculated and discussed in detail. The numerical results show that there are three branches of interface optical phonons. One branch exists in low frequency region; another two branches exist in high frequency region. The interface optical phonons with small quantum number l have more important contributions to the electron-phonon interactions. It is also found that ternary mixed effects have important influences on the interface optical phonon properties in a single zinc-blende GaN/AlxGa1-xN quantum dot. With the increase of Al component, the interface optical phonon frequencies appear linear changes, and the electron-phonon coupling strengths appear non-linear changes in high frequency region. But in low frequency region, the frequencies appear non-linear changes, and the electron-phonon coupling strengths appear linear changes.

Dual spherical single-mode-multimode-single-mode optical fiber temperature sensor based on a Mach–Zehnder interferometer

NASA Astrophysics Data System (ADS)

Tan, Jianchang; Feng, Guoying; Zhang, Shulin; Liang, Jingchuan; Li, Wei; Luo, Yun

2018-07-01

A dual spherical single-mode-multimode-single-mode (DSSMS) optical fiber temperature sensor based on a Mach–Zehnder interferometer (MZI) was designed and implemented in this paper. Theoretical and experimental results indicated that the LP01 mode in the core and the LP09 mode excited by the spherical structure were maintained and transmitted via multimode fiber and interfered at the second spherical structure, resulting in the interference spectrum. An increase or decrease in temperature can cause significant red-shift or blue-shift of the spectrum, respectively. The linearity of the spectral shift due to the temperature change is ~0.999, the sensitivity at 30 °C–540 °C is ~37.372 pm °C‑3, and at  ‑25 °C–25 °C is ~37.28 pm °C‑1. The reproducibility error of this all-fiber temperature sensor at 30 °C–540 °C is less than 0.15%. Compared with the optical fiber sensor with a tapered structure and fiber core offset structure, this MZI-based DSSMS optical fiber temperature sensor has higher mechanical strength. Moreover, benefiting from low-cost and environmentally friendly materials, it is expected to be a novel micro-nano all-fiber sensor.

OPTICS OF CONDUCTIVE KERATOPLASTY: IMPLICATIONS FOR PRESBYOPIA MANAGEMENT

PubMed Central

Hersh, Peter S

2005-01-01

Purpose To define the corneal optics of conductive keratoplasty (CK) and assess the clinical implications for hyperopia and presbyopia management. Methods Four analyses were done. (1) Multifocal effects: In a prospective study of CK, uncorrected visual acuity (UCVA) for a given refractive error in 72 postoperative eyes was compared to control eyes. (2) Surgically induced astigmatism (SIA): 203 eyes were analyzed for magnitude and axis of SIA. (3) Higher-order optical aberrations: Corneal higher-order optical aberrations were assessed for 36 eyes after CK and a similar patient population after hyperopic laser in situ keratomileusis (LASIK). (4) Presbyopia clinical trial: Visual acuity, refractive result, and patient questionnaires were analyzed for 150 subjects in a prospective, multicenter clinical trial of presbyopia management with CK. Results (1) 63% and 82% of eyes after CK had better UCVA at distance and near, respectively, than controls. (2) The mean SIA was 0.23 diopter (D) steepening at 175° (P < .001); mean magnitude was 0.66 D (SD, 0.43 D). (3) After CK, composite fourth- and sixth-order spherical aberration increased; change in (Z12) spherical aberration alone was not statistically significant. When compared to hyperopic LASIK, there was a statistically significant increase in composite fourth- and sixth-order spherical aberration (P < .01) and spherical aberration (Z12) alone (P < .02); spherical aberration change was more prolate after CK. (4) After the CK monovision procedure, 80% of patients had J3 or better binocular UCVA at near; 84% of patients were satisfied. Satisfaction was associated with near UCVA of J3 or better in the monovision eye (P = .001) and subjectively good postoperative depth perception (P = .038). Conclusions CK seems to produce functional corneal multifocality with definable introduction of SIA and higher-order optical aberrations, and development of a more prolate corneal contour. These optical factors may militate toward improved near vision function. PMID:17057812

All-reflective optical target illumination system with high numerical aperture

DOEpatents

Sigler, Robert D.

1978-01-01

An all-reflective optical system for providing illumination of a target focal region at high numerical aperture from a pair of co-axially, confluent collimated light beams. A target cavity is defined by a pair of opposed inner ellipsoidal reflectors having respective first focal points within a target region and second focal points at a vertex opening in the opposing reflector. Outwardly of each inner reflector is the opposed combination of a spherical reflector, and an outer generally ellipsoidal reflector having an aberrated first focal point coincident with the focus of the opposing spherical reflector and a second focal point coincident with the second focal point of the opposing inner ellipsoidal reflector through a vertex opening in the spherical reflector. The confluent collimated beams are incident through vertex openings in the outer ellipsoidal reflectors onto respective opposing spherical reflectors. Each beam is reflected by the associated spherical reflector onto the opposing outer ellipsoidal reflector and focused thereby onto the opposing inner ellipsoidal reflector, and then onto the target region.

Phonon impact on optical control schemes of quantum dots: Role of quantum dot geometry and symmetry

NASA Astrophysics Data System (ADS)

Lüker, S.; Kuhn, T.; Reiter, D. E.

2017-12-01

Phonons strongly influence the optical control of semiconductor quantum dots. When modeling the electron-phonon interaction in several theoretical approaches, the quantum dot geometry is approximated by a spherical structure, though typical self-assembled quantum dots are strongly lens-shaped. By explicitly comparing simulations of a spherical and a lens-shaped dot using a well-established correlation expansion approach, we show that, indeed, lens-shaped dots can be exactly mapped to a spherical geometry when studying the phonon influence on the electronic system. We also give a recipe to reproduce spectral densities from more involved dots by rather simple spherical models. On the other hand, breaking the spherical symmetry has a pronounced impact on the spatiotemporal properties of the phonon dynamics. As an example we show that for a lens-shaped quantum dot, the phonon emission is strongly concentrated along the direction of the smallest axis of the dot, which is important for the use of phonons for the communication between different dots.

Correcting spherical aberrations induced by an unknown medium through determination of its refractive index and thickness.

PubMed

Iwaniuk, Daniel; Rastogi, Pramod; Hack, Erwin

2011-09-26

In imaging and focusing applications, spherical aberration induces axial broadening of the point spread function (PSF). A transparent medium between lens and object of interest induces spherical aberration. We propose a method that first obtains both the physical thickness and the refractive index of the aberration inducing medium in situ by measuring the induced focal shifts for paraxial and large angle rays. Then, the fourth order angle dependence of the optical path difference inside the medium is used to correct the spherical aberration using a phase-only spatial light modulator. The obtained measurement accuracy of 3% is sufficient for a complete compensation as demonstrated in a model microscope with NA 0.3 with glass plate induced axial broadening of the PSF by a factor of 5. © 2011 Optical Society of America

Prospects of photonic nanojets for precise exposure on microobjects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geints, Yu. E., E-mail: ygeints@iao.ru; Zuev Institute of Atmospheric Optics, SB Russian Academy of Sciences, Acad. Zuev Square 1, Tomsk, 634021; Panina, E. K., E-mail: pek@iao.ru

We report on the new optical tool for precise manipulation of various microobjects. This tool is referred to as a “photonic nanojet” (PJ) and corresponds to specific spatially localized and high-intensity area formed near micron-sized transparent spherical dielectric particles illuminated by a visible laser radiation The descriptive analysis of the morphological shapes of photonic nanojets is presented. The PJ shape characterization is based on the numerical calculations of the near-field distribution according to the Mie theory and accounts for jet dimensions and shape complexity.

The room-temperature synthesis of anisotropic CdHgTe quantum dot alloys: a "molecular welding" effect.

PubMed

Taniguchi, Shohei; Green, Mark; Lim, Teck

2011-03-16

The room-temperature chemical transformation of spherical CdTe nanoparticles into anisotropic alloyed CdHgTe particles using mercury bromide in a toluene/methanol system at room temperature has been investigated. The resulting materials readily dissolved in toluene and exhibited a significant red-shift in the optical properties toward the infrared region. Structural transformations were observed, with electron microscopy showing that the CdTe nanoparticles were chemically attached ('welded') to other CdTe nanoparticles, creating highly complex anisotropic heterostructures which also incorporated mercury.

Spherical transceivers for ultrafast optical wireless communications

NASA Astrophysics Data System (ADS)

Jin, Xian; Hristovski, Blago A.; Collier, Christopher M.; Geoffroy-Gagnon, Simon; Born, Brandon; Holzman, Jonathan F.

2016-02-01

Optical wireless communications (OWC) offers the potential for high-speed and mobile operation in indoor networks. Such OWC systems often employ a fixed transmitter grid and mobile transceivers, with the mobile transceivers carrying out bi-directional communication via active downlinks (ideally with high-speed signal detection) and passive uplinks (ideally with broad angular retroreflection and high-speed modulation). It can be challenging to integrate all of these bidirectional communication capabilities within the mobile transceivers, however, as there is a simultaneous desire for compact packaging. With this in mind, the work presented here introduces a new form of transceiver for bi-directional OWC systems. The transceiver incorporates radial photoconductive switches (for high-speed signal detection) and a spherical retro-modulator (for broad angular retroreflection and high-speed all-optical modulation). All-optical retromodulation are investigated by way of theoretical models and experimental testing, for spherical retro-modulators comprised of three glasses, N-BK7, N-LASF9, and S-LAH79, having differing levels of refraction and nonlinearity. It is found that the spherical retro-modulator comprised of S-LAH79, with a refractive index of n ≍ 2 and a Kerr nonlinear index of n2 ≍ (1.8 ± 0.1) × 10-15 cm2/W, yields both broad angular retroreflection (over a solid angle of 2π steradians) and ultrafast modulation (over a duration of 120 fs). Such transceivers can become important elements for all-optical implementations in future bi-directional OWC systems.

Inverting Image Data For Optical Testing And Alignment

NASA Technical Reports Server (NTRS)

Shao, Michael; Redding, David; Yu, Jeffrey W.; Dumont, Philip J.

1993-01-01

Data from images produced by slightly incorrectly figured concave primary mirror in telescope processed into estimate of spherical aberration of mirror, by use of algorithm finding nonlinear least-squares best fit between actual images and synthetic images produced by multiparameter mathematical model of telescope optical system. Estimated spherical aberration, in turn, converted into estimate of deviation of reflector surface from nominal precise shape. Algorithm devised as part of effort to determine error in surface figure of primary mirror of Hubble space telescope, so corrective lens designed. Modified versions of algorithm also used to find optical errors in other components of telescope or of other optical systems, for purposes of testing, alignment, and/or correction.

Rotation of single live mammalian cells using dynamic holographic optical tweezers

NASA Astrophysics Data System (ADS)

Bin Cao; Kelbauskas, Laimonas; Chan, Samantha; Shetty, Rishabh M.; Smith, Dean; Meldrum, Deirdre R.

2017-05-01

We report on a method for rotating single mammalian cells about an axis perpendicular to the optical system axis through the imaging plane using dynamic holographic optical tweezers (HOTs). Two optical traps are created on the opposite edges of a mammalian cell and are continuously transitioned through the imaging plane along the circumference of the cell in opposite directions, thus providing the torque to rotate the cell in a controlled fashion. The method enables a complete 360° rotation of live single mammalian cells with spherical or near-to spherical shape in 3D space, and represents a useful tool suitable for the single cell analysis field, including tomographic imaging.

Zoom system without moving element by using two liquid crystal lenses with spherical electrode

NASA Astrophysics Data System (ADS)

Yang, Ren-Kai; Lin, Chia-Ping; Su, Guo-Dung J.

2017-08-01

A traditional zoom system is composed of several elements moving relatively toward other components to achieve zooming. Unlike tradition system, an electrically control zoom system with liquid crystal (LC) lenses is demonstrated in this paper. To achieve zooming, we apply two LC lenses whose optical power is controlled by voltage to replace two moving lenses in traditional zoom system. The mechanism of zoom system is to use two LC lenses to form a simple zoom system. We found that with such spherical electrodes, we could operate LC lens at voltage range from 31V to 53 V for 3X tunability in optical power. For each LC lens, we use concave spherical electrode which provide lower operating voltage and great tunability in optical power, respectively. For such operating voltage and compact size, this zoom system with zoom ratio approximate 3:1 could be applied to mobile phone, camera and other applications.

Multichannel optical sensing device

DOEpatents

Selkowitz, S.E.

1985-08-16

A multichannel optical sensing device is disclosed, for measuring the outdoor sky luminance or illuminance or the luminance or illuminance distribution in a room, comprising a plurality of light receptors, an optical shutter matrix including a plurality of liquid crystal optical shutter elements operable by electrical control signals between light transmitting and light stopping conditions, fiber optical elements connected between the receptors and the shutter elements, a microprocessor based programmable control unit for selectively supplying control signals to the optical shutter elements in a programmable sequence, a photodetector including an optical integrating spherical chamber having an input port for receiving the light from the shutter matrix and at least one detector element in the spherical chamber for producing output signals corresponding to the light, and output units for utilizing the output signals including a storage unit having a control connection to the microprocessor based programmable control unit for storing the output signals under the sequence control of the programmable control unit.

Multichannel optical sensing device

DOEpatents

Selkowitz, Stephen E.

1990-01-01

A multichannel optical sensing device is disclosed, for measuring the outr sky luminance or illuminance or the luminance or illuminance distribution in a room, comprising a plurality of light receptors, an optical shutter matrix including a plurality of liquid crystal optical shutter elements operable by electrical control signals between light transmitting and light stopping conditions, fiber optic elements connected between the receptors and the shutter elements, a microprocessor based programmable control unit for selectively supplying control signals to the optical shutter elements in a programmable sequence, a photodetector including an optical integrating spherical chamber having an input port for receiving the light from the shutter matrix and at least one detector element in the spherical chamber for producing output signals corresponding to the light, and output units for utilizing the output signals including a storage unit having a control connection to the microprocessor based programmable control unit for storing the output signals under the sequence control of the programmable control unit.

Spherical tensor analysis of polar liquid crystals with biaxial and chiral molecules

NASA Astrophysics Data System (ADS)

Iwamoto, Mitsumasa; Zhong-can, Ou-Yang

2012-11-01

With the help of spherical tensor expression, an irreducible calculus of a Lth-rank macroscopic susceptibility χ for a polar liquid crystal (PLC) of biaxial and chiral molecules written as the average of molecular hyperpolarizability tensor β associated with their spherical orientational order parameters (0⩽l⩽L) is presented. Comprehensive formulas of L=1,2 have been obtained and the latter explains the optical activity and spontaneous splay texture observed in bent-core PLC. The expression of L=3 specifies for the molecules with D2 symmetry which can be applied to analyze the nonlinear optical second harmonic generation (SHG) observed in proteins, peptides, and double-stranded DNA at interfaces.

Calibration of optical particle-size analyzer

DOEpatents

Pechin, William H.; Thacker, Louis H.; Turner, Lloyd J.

1979-01-01

This invention relates to a system for the calibration of an optical particle-size analyzer of the light-intercepting type for spherical particles, wherein a rotary wheel or disc is provided with radially-extending wires of differing diameters, each wire corresponding to a particular equivalent spherical particle diameter. These wires are passed at an appropriate frequency between the light source and the light detector of the analyzer. The reduction of light as received at the detector is a measure of the size of the wire, and the electronic signal may then be adjusted to provide the desired signal for corresponding spherical particles. This calibrator may be operated at any time without interrupting other processing.

Numerical aperture limits on efficient ball lens coupling of laser diodes to single-mode fibers with defocus to balance spherical aberration

NASA Technical Reports Server (NTRS)

Wilson, R. Gale

1994-01-01

The potential capabilities and limitations of single ball lenses for coupling laser diode radiation to single-mode optical fibers have been analyzed; parameters important to optical communications were specifically considered. These parameters included coupling efficiency, effective numerical apertures, lens radius, lens refractive index, wavelength, magnification in imaging the laser diode on the fiber, and defocus to counterbalance spherical aberration of the lens. Limiting numerical apertures in object and image space were determined under the constraint that the lens perform to the Rayleigh criterion of 0.25-wavelength (Strehl ratio = 0.80). The spherical aberration-defocus balance to provide an optical path difference of 0.25 wavelength units was shown to define a constant coupling efficiency (i.e., 0.56). The relative numerical aperture capabilities of the ball lens were determined for a set of wavelengths and associated fiber-core diameters of particular interest for single-mode fiber-optic communication. The results support general continuing efforts in the optical fiber communications industry to improve coupling links within such systems with emphasis on manufacturing simplicity, system packaging flexibility, relaxation of assembly alignment tolerances, cost reduction of opto-electronic components and long term reliability and stability.

Whispering gallery modes in a spherical microcavity with a photoluminescent shell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grudinkin, S. A., E-mail: grudink@gvg.ioffe.ru; Dontsov, A. A.; Feoktistov, N. A.

2015-10-15

Whispering-gallery mode spectra in optical microcavities based on spherical silica particles coated with a thin photoluminescent shell of hydrogenated amorphous silicon carbide are studied. The spectral positions of the whispering-gallery modes for spherical microcavities with a shell are calculated. The dependence of the spectral distance between the TE and TM modes on the shell thickness is examined.

Method of increasing power within an optical cavity with long path lengths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leen, John Brian; Bramall, Nathan E.

A cavity-enhanced absorption spectroscopy instrument has an optical cavity with two or more cavity mirrors, one mirror of which having a hole or other aperture for injecting a light beam, and the same or another mirror of which being partially transmissive to allow exit of light to a detector. A spherical-spherical configuration with at least one astigmatic mirror or a spherical-cylindrical configuration where the spherical mirror could also be astigmatic prevents a reentrant condition wherein the injected beam would prematurely exit the cavity through the aperture. This combination substantially increases the number of passes of the injected beam through amore » sample volume for sensitive detection of chemical species even in less than ideal conditions including low power laser or LED sources, poor mirror reflectivity or detector noise at the wavelengths of interest, or cavity alignment issues such as vibration or temperature and pressure changes.« less

Effect of the internal optics on the outcome of custom-LASIK in an eye model

NASA Astrophysics Data System (ADS)

Manns, Fabrice; Ho, Arthur; Parel, Jean-Marie

2004-07-01

Purpose. The purpose of this study was to evaluate if changes in the aberration-contribution of the internal optics of the eye have a significant effect on the outcome of wavefront-guided corneal reshaping. Methods. The Navarro-Escudero eye model was simulated using optical analysis software. The eye was rendered myopic by shifting the plane of the retina. Custom-LASIK was simulated by changing the radius of curvature and asphericity of the anterior corneal surface of the eye model. The radius of curvature was adjusted to provide a retinal conjugate at infinity. Three approaches were used to determine the postoperative corneal asphericity: minimizing third-order spherical aberration, minimizing third-order coma, and maximizing the Strehl ratio. The aberration contribution of the anterior corneal surface and internal optics was calculated before and after each simulated customized correction. Results. For a 5.2mm diameter pupil, the contribution of the anterior corneal surface to third-order spherical aberration and coma (in micrometers) was 2.22 and 2.49 preop, -0.36 and 2.83 postop when spherical aberration is minimized, 5.88 and 1.10 postop when coma is minimized, and -0.63 and 2.91 postop when Strehl ratio is maximized. The contribution of the internal optics of the eye to spherical aberration and coma for the same four conditions was: 0.43 and -1.13, 0.37 and -1.10, 0.37 and -1.10 and 0.37 and -1.10, respectively. Conclusion. In the model eye, the contribution of the internal optics of the eye to the change in the ocular aberration state is negligible.

Scattering and Absorption Properties of Polydisperse Wavelength-sized Particles Covered with Much Smaller Grains

NASA Technical Reports Server (NTRS)

Dlugach, Jana M.; Mishchenko, Michael I.; Mackowski, Daniel W.

2012-01-01

Using the results of direct, numerically exact computer solutions of the Maxwell equations, we analyze scattering and absorption characteristics of polydisperse compound particles in the form of wavelength-sized spheres covered with a large number of much smaller spherical grains.The results pertain to the complex refractive indices1.55 + i0.0003,1.55 + i0.3, and 3 + i0.1. We show that the optical effects of dusting wavelength-sized hosts by microscopic grains can vary depending on the number and size of the grains as well as on the complex refractive index. Our computations also demonstrate the high efficiency of the new superposition T-matrix code developed for use on distributed memory computer clusters.

Calculation of total and ionization cross sections for electron scattering by primary benzene compounds

NASA Astrophysics Data System (ADS)

Singh, Suvam; Naghma, Rahla; Kaur, Jaspreet; Antony, Bobby

2016-07-01

The total and ionization cross sections for electron scattering by benzene, halobenzenes, toluene, aniline, and phenol are reported over a wide energy domain. The multi-scattering centre spherical complex optical potential method has been employed to find the total elastic and inelastic cross sections. The total ionization cross section is estimated from total inelastic cross section using the complex scattering potential-ionization contribution method. In the present article, the first theoretical calculations for electron impact total and ionization cross section have been performed for most of the targets having numerous practical applications. A reasonable agreement is obtained compared to existing experimental observations for all the targets reported here, especially for the total cross section.

Colloidal synthesis of monodispersed ZnS and CdS nanocrystals from novel zinc and cadmium complexes

NASA Astrophysics Data System (ADS)

Onwudiwe, Damian C.; Mohammed, Aliyu D.; Strydom, Christien A.; Young, Desmond A.; Jordaan, Anine

2014-06-01

Monodispersed spherical and hexagonal shaped ZnS and CdS nanocrystals respectively, have been synthesized using novel heteroleptic complexes of xanthate (S2CObu) and dithiocarbamate (S2CNMePh). The nanocrystals were prepared via colloidal route and stabilized in hexadecylamine (HDA). The morphology of the as-prepared nanocrystals was characterized using transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), and powdered X-ray diffraction (p-XRD) analysis. An average diameter of 7.2 nm and 8.6 nm were obtained for the ZnS and CdS respectively. The optical properties of the nanoparticles studied by UV-vis and photoluminescence (PL) spectroscopy showed a blue shift in the absorption spectra, and band edge emission respectively.

Generation of ultra-long pure magnetization needle and multiple spots by phase modulated doughnut Gaussian beam

NASA Astrophysics Data System (ADS)

Udhayakumar, M.; Prabakaran, K.; Rajesh, K. B.; Jaroszewicz, Z.; Belafhal, Abdelmajid; Velauthapillai, Dhayalan

2018-06-01

Based on vector diffraction theory and inverse Faraday effect (IFE), the light induced magnetization distribution of a tightly focused azimuthally polarized doughnut Gaussian beam superimposed with a helical phase and modulated by an optimized multi belt complex phase filter (MBCPF) is analysed numerically. It is noted that by adjusting the radii of different rings of the complex phase filter, one can achieve many novel magnetization focal distribution such as sub wavelength scale (0.29λ) and super long (52.2λ) longitudinal magnetic probe suitable for all optical magnetic recording and the formation of multiple magnetization chain with four, six and eight sub-wavelength spherical magnetization spots suitable for multiple trapping of magnetic particles are achieved.

Investigation of quadratic electro-optic effects and electro-absorption process in GaN/AlGaN spherical quantum dot

PubMed Central

2014-01-01

Quadratic electro-optic effects (QEOEs) and electro-absorption (EA) process in a GaN/AlGaN spherical quantum dot are theoretically investigated. It is found that the magnitude and resonant position of third-order nonlinear optical susceptibility depend on the nanostructure size and aluminum mole fraction. With increase of the well width and barrier potential, quadratic electro-optic effect and electro-absorption process nonlinear susceptibilities are decreased and blueshifted. The results show that the DC Kerr effect in this case is much larger than that in the bulk case. Finally, it is observed that QEOEs and EA susceptibilities decrease and broaden with the decrease of relaxation time. PMID:24646318

Observer for a thick layer of solid deuterium-tritium using backlit optical shadowgraphy and interferometry.

PubMed

Choux, Alexandre; Busvelle, Eric; Gauthier, Jean Paul; Pascal, Ghislain

2007-11-20

Our work is in the context of the French "laser mégajoule" project, about fusion by inertial confinement. The project leads to the problem of characterizing the inner surface, of the approximately spherical target, by optical shadowgraphy techniques. Our work is entirely based on the basic idea that optical shadowgraphy produces "caustics" of systems of optical rays, which contain a great deal of 3D information about the surface to be characterized. We develop a method of 3D reconstruction based upon this idea plus a "small perturbations" technique. Although computations are made in the special "spherical" case, the method is in fact general and may be extended to several other situations.

Optical approach to the salivary pellicle

NASA Astrophysics Data System (ADS)

Baek, Jae Ho; Krasieva, Tatiana; Tang, Shuo; Ahn, Yehchan; Kim, Chang Soo; Vu, Diana; Chen, Zhongping; Wilder-Smith, Petra

2009-07-01

The salivary pellicle plays an important role in oral physiology, yet noninvasive in situ characterization and mapping of this layer remains elusive. The goal of this study is to develop an optical approach for the real-time, noninvasive mapping and characterization of salivary pellicles using optical coherence tomography (OCT) and optical coherence microscopy (OCM). The long-term goals are to improve diagnostic capabilities in the oral cavity, gain a better understanding of physiological and pathological processes related to the oral hard tissues, and monitor treatment responses. A salivary pellicle is incubated on small enamel cubes using human whole saliva. OCT and OCM imaging occurs at 0, 10, 30, 60 min, and 24 h. For some imaging, spherical gold nanoparticles (15 nm) are added to determine whether this would increase the optical signal from the pellicle. Multiphoton microscopy (MPM) provides the baseline information. In the saliva-incubated samples, a surface signal from the developing pellicle is visible in OCT images. Pellicle ``islands'' form, which increase in complexity over time until they merge to form a continuous layer over the enamel surface. Noninvasive, in situ time-based pellicle formation on the enamel surface is visualized and characterized using optical imaging.

Photonic jet etching: Justifying the shape of optical fiber tip

NASA Astrophysics Data System (ADS)

Abdurrochman, Andri; Zelgowski, Julien; Lecler, Sylvain; Mermet, Frédéric; Tumbelaka, Bernard; Fontaine, Joël

2016-02-01

Photonic jet (PJ) is a low diverging and highly concentrated beam in the shadow side of dielectric particle (cylinder or sphere). The concentration can be more than 200 times higher than the incidence wave. It is a non-resonance phenomenon in the near-field can propagate in a few wavelengths. Many potential applications have been proposed, including PJ etching. Hence, a guided-beam is considered increasing the PJ mobility control. While the others used a combination of classical optical fibers and spheres, we are concerned on a classical optical fiber with spherical tip to generate the PJ. This PJ driven waveguide has been realized using Gaussian mode beam inside the core. It has different variable parameters compared to classical PJ, which will be discussed in correlation with the etching demonstrations. The parameters dependency between the tip and PJ properties are complex; and theoretical aspect of this interaction will be exposed to justify the shape of our tip and optical fiber used in our demonstrations. Methods to achieve such a needed optical fiber tip will also be described. Finally the ability to generate PJ out of the shaped optical fiber will be experimentally demonstrated and the potential applications for material processing will be exposed.

Vertical interferometer workstation for testing large spherical optics

NASA Astrophysics Data System (ADS)

Truax, B.

2013-09-01

The design of an interferometer workstation for the testing of large concave and convex spherical optics is presented. The workstation handles optical components and mounts up to 425 mm in diameter with mass of up to 40 kg with 6 axes of adjustment. A unique method for the implementation of focus, roll and pitch was used allowing for extremely precise adjustment. The completed system includes transmission spheres with f-numbers from f/1.6 to f/0.82 incorporating reference surface diameters of up to 306 mm and surface accuracies of better than 63 nm PVr. The design challenges and resulting solutions are discussed. System performance results are presented.

OPTOELECTRONICS, FIBER OPTICS, AND OTHER ASPECTS OF QUANTUM ELECTRONICS: Integrated-optical spectrum analyzer based on Ti:LiNbO3 with an optimized system of interdigital transducers and spherical geodesic lenses

NASA Astrophysics Data System (ADS)

Golovanova, T. M.; Gryaznov, Yu M.; Dianov, Evgenii M.; Dobryakova, N. G.; Kiselev, A. V.; Prokhorov, A. M.; Shcherbakov, E. A.

1989-08-01

An investigation was made of the parameters of an integrated-optical spectrum analyzer consisting of a Ti:LiNbO3 crystal and a semiconductor laser with a built-in microobjective, spherical geodesic lenses, and an optimized system of interdigital (opposed-comb) transducers. The characteristics of this spectrum analyzer were as follows: the band of operating frequencies was 181 MHz (at the 3 dB level); the resolution was 2.8 MHz; the signal/noise ratio (under a control voltage of 4 V) was 20 dB.

Cavity enhanced atomic magnetometry

PubMed Central

Crepaz, Herbert; Ley, Li Yuan; Dumke, Rainer

2015-01-01

Atom sensing based on Faraday rotation is an indispensable method for precision measurements, universally suitable for both hot and cold atomic systems. Here we demonstrate an all-optical magnetometer where the optical cell for Faraday rotation spectroscopy is augmented with a low finesse cavity. Unlike in previous experiments, where specifically designed multipass cells had been employed, our scheme allows to use conventional, spherical vapour cells. Spherical shaped cells have the advantage that they can be effectively coated inside with a spin relaxation suppressing layer providing long spin coherence times without addition of a buffer gas. Cavity enhancement shows in an increase in optical polarization rotation and sensitivity compared to single-pass configurations. PMID:26481853

Optimization of spherical facets for parabolic solar concentrators

NASA Technical Reports Server (NTRS)

White, J. E.; Erikson, R. J.; Sturgis, J. D.; Elfe, T. B.

1986-01-01

Solar concentrator designs which employ deployable hexagonal panels are being developed for space power systems. An offset optical configuration has been developed which offers significant system level advantages over previously proposed collector designs for space applications. Optical analyses have been performed which show offset reflector intercept factors to be only slightly lower than those for symmetric reflectors with the same slope error. Fluxes on the receiver walls are asymmetric but manageable by varying the tilt angle of the receiver. Greater producibility is achieved by subdividing the hexagonal panels into triangular mirror facets of spherical contour. Optical analysis has been performed upon these to yield near-optimum sizes and radii.

Correction-free pyrometry in radiant wall furnaces

NASA Technical Reports Server (NTRS)

Thomas, Andrew S. W. (Inventor)

1994-01-01

A specular, spherical, or near-spherical target is located within a furnace having inner walls and a viewing window. A pyrometer located outside the furnace 'views' the target through pyrometer optics and the window, and it is positioned so that its detector sees only the image of the viewing window on the target. Since this image is free of any image of the furnace walls, it is free from wall radiance, and correction-free target radiance is obtained. The pyrometer location is determined through a nonparaxial optical analysis employing differential optical ray tracing methods to derive a series of exact relations for the image location.

Dispersion in Spherical Water Drops.

ERIC Educational Resources Information Center

Eliason, John C., Jr.

1989-01-01

Discusses a laboratory exercise simulating the paths of light rays through spherical water drops by applying principles of ray optics and geometry. Describes four parts: determining the output angles, computer simulation, explorations, model testing, and solutions. Provides a computer program and some diagrams. (YP)

Investigation on Dynamic Calibration for an Optical-Fiber Solids Concentration Probe in Gas-Solid Two-Phase Flows

PubMed Central

Xu, Guiling; Liang, Cai; Chen, Xiaoping; Liu, Daoyin; Xu, Pan; Shen, Liu; Zhao, Changsui

2013-01-01

This paper presents a review and analysis of the research that has been carried out on dynamic calibration for optical-fiber solids concentration probes. An introduction to the optical-fiber solids concentration probe was given. Different calibration methods of optical-fiber solids concentration probes reported in the literature were reviewed. In addition, a reflection-type optical-fiber solids concentration probe was uniquely calibrated at nearly full range of the solids concentration from 0 to packed bed concentration. The effects of particle properties (particle size, sphericity and color) on the calibration results were comprehensively investigated. The results show that the output voltage has a tendency to increase with the decreasing particle size, and the effect of particle color on calibration result is more predominant than that of sphericity. PMID:23867745

Resonant Optical Circuits Based on Coupling Between Whispering Gallery Modes in Dielectric Microresonators

DTIC Science & Technology

2007-12-30

111111 (2006). 2. S.P. Ashili , V.N. Astratov, and E.C.H. Sykes, “The effects of inter-cavity separation on optical coupling in dielectric bispheres...chains of coupled spherical cavities,” Opt. Lett. 32, 409-411 (2007). 4. V.N. Astratov, and S.P. Ashili , “Percolation of light through whispering...Propagation via Whispering Gallery Modes in 3-D Networks of Coupled Spherical Cavities (Talk), V.N. Astratov, S.P. Ashili , and A.M. Kapitonov, in Frontiers in

Novel Payload Architectures for LISA

NASA Astrophysics Data System (ADS)

Johann, Ulrich A.; Gath, Peter F.; Holota, Wolfgang; Schulte, Hans Reiner; Weise, Dennis

2006-11-01

As part of the current LISA Mission Formulation Study, and based on prior internal investigations, Astrium Germany has defined and preliminary assessed novel payload architectures, potentially reducing overall complexity and improving budgets and costs. A promising concept is characterized by a single active inertial sensor attached to a single optical bench and serving both adjacent interferometer arms via two rigidly connected off-axis telescopes. The in-plane triangular constellation ``breathing angle'' compensation is accomplished by common telescope in-field of view pointing actuation of the transmit/received beams line of sight. A dedicated actuation mechanism located on the optical bench is required in addition to the on bench actuators for differential pointing of the transmit and receive direction perpendicular to the constellation plane. Both actuators operate in a sinusoidal yearly period. A technical challenge is the actuation mechanism pointing jitter and the monitoring and calibration of the laser phase walk which occurs while changing the optical path inside the optical assembly during re-pointing. Calibration or monitoring of instrument internal phase effects e.g. by a laser metrology truss derived from the existing interferometry is required. The architecture exploits in full the two-step interferometry (strap down) concept, separating functionally inter spacecraft and intra-spacecraft interferometry (reference mass laser metrology degrees of freedom sensing). The single test mass is maintained as cubic, but in free-fall in the lateral degrees of freedom within the constellation plane. Also the option of a completely free spherical test mass with full laser interferometer readout has been conceptually investigated. The spherical test mass would rotate slowly, and would be allowed to tumble. Imperfections in roundness and density would be calibrated from differential wave front sensing in a tetrahedral arrangement, supported by added attitude information via a grid of tick marks etched onto the surface and monitored by the laser readout.

Microsystems in medicine.

PubMed

Wallrabe, U; Ruther, P; Schaller, T; Schomburg, W K

1998-03-01

The complexity of modern surgical and analytical methods requires the miniaturisation of many medical devices. The LIGA technique and also mechanical microengineering are well known for the batch fabrication of microsystems. Actuators and sensors are developed based on these techniques. The hydraulic actuation principle is advantageous for medical applications since the energy may be supplied by pressurised balanced salt solution. Some examples are turbines, pumps and valves. In addition, optical sensors and components are useful for analysis and inspection as represented by microspectrometers and spherical lenses. Finally, plastic containers with microporous bottoms allow a 3-dimensional growth of cell culture systems.

Ab initio method for calculating total cross sections

NASA Technical Reports Server (NTRS)

Bhatia, A. K.; Schneider, B. I.; Temkin, A.

1993-01-01

A method for calculating total cross sections without formally including nonelastic channels is presented. The idea is to use a one channel T-matrix variational principle with a complex correlation function. The derived T matrix is therefore not unitary. Elastic scattering is calculated from T-parallel-squared, but total scattering is derived from the imaginary part of T using the optical theorem. The method is applied to the spherically symmetric model of electron-hydrogen scattering. No spurious structure arises; results for sigma(el) and sigma(total) are in excellent agreement with calculations of Callaway and Oza (1984). The method has wide potential applicability.

Behaviors of ellipsoidal micro-particles within a two-beam optical levitator

NASA Astrophysics Data System (ADS)

Petkov, T.; Yang, M.; Ren, K. F.; Pouligny, B.; Loudet, J.-C.

2017-07-01

The two-beam levitator (TBL) is a standard optical setup made of a couple of counter-propagating beams. Note worthily, TBLs allow the manipulation and trapping of particles at long working distances. While much experience has been accumulated in the trapping of single spherical particles in TBLs, the behaviors of asymmetrical particles turn out to be more complex, and even surprising. Here, we report observations with prolate ellipsoidal polystyrene particles, with varying aspect ratio and ratio of the two beam powers. Generalizing the earlier work by Mihiretie et al. in single beam geometries [JQSRT 126, 61 (2013)], we observe that particles may be either static, or permanently oscillating, and that the two-beam geometry produces new particle responses: some of them are static, but non-symmetrical, while others correspond to new types of oscillations. A two-dimensional model based on ray-optics qualitatively accounts for these configurations and for the "primary" oscillations of the particles. Furthermore, levitation powers measured in the experiments are in fair agreement with those computed from GLMT (Generalized Lorentz Mie Theory), MLFMA (Multilevel Fast Multipole Algorithm) and approximate ray-optics methods.

An optical potential for the statically deformed actinide nuclei derived from a global spherical potential

NASA Astrophysics Data System (ADS)

Al-Rawashdeh, S. M.; Jaghoub, M. I.

2018-04-01

In this work we test the hypothesis that a properly deformed spherical optical potential, used within a channel-coupling scheme, provides a good description for the scattering data corresponding to neutron induced reactions on the heavy, statically deformed actinides and other lighter deformed nuclei. To accomplish our goal, we have deformed the Koning-Delaroche spherical global potential and then used it in a channel-coupling scheme. The ground-state is coupled to a sufficient number of inelastic rotational channels belonging to the ground-state band to ensure convergence. The predicted total cross sections, elastic and inelastic angular distributions are in good agreement with the experimental data. As a further test, we compare our results to those obtained by a global channel-coupled optical model whose parameters were obtained by fitting elastic and inelastic angular distributions in addition to total cross sections. Our results compare quite well with those obtained by the fitted, channel-coupled optical model. Below neutron incident energies of about 1MeV, our results show that scattering into the rotational excited states of the ground-state band plays a significant role in the scattering process and must be explicitly accounted for using a channel-coupling scheme.

On the Geometrical Optics Approach in the Theory of Freely-Localized Microwave Gas Breakdown

NASA Astrophysics Data System (ADS)

Shapiro, Michael; Schaub, Samuel; Hummelt, Jason; Temkin, Richard; Semenov, Vladimir

2015-11-01

Large filamentary arrays of high pressure gas microwave breakdown have been experimentally studied at MIT using a 110 GHz, 1.5 MW pulsed gyrotron. The experiments have been modeled by other groups using numerical codes. The plasma density distribution in the filaments can be as well analytically calculated using the geometrical optics approach neglecting plasma diffusion. The field outside the filament is a solution of an inverse electromagnetic problem. The solutions are found for the cylindrical and spherical filaments and for the multi-layered planar filaments with a finite plasma density at the boundaries. We present new results of this theory showing a variety of filaments with complex shapes. The solutions for plasma density distribution are found with a zero plasma density at the boundary of the filament. Therefore, to solve the inverse problem within the geometrical optics approximation, it can be assumed that there is no reflection from the filament. The results of this research are useful for modeling future MIT experiments.

Electromagnetically induced transparency in a multilayered spherical quantum dot with hydrogenic impurity

NASA Astrophysics Data System (ADS)

Pavlović, Vladan; Šušnjar, Marko; Petrović, Katarina; Stevanović, Ljiljana

2018-04-01

In this paper the effects of size, hydrostatic pressure and temperature on electromagnetically induced transparency, as well as on absorption and the dispersion properties of multilayered spherical quantum dot with hydrogenic impurity are theoretically investigated. Energy eigenvalues and wavefunctions of quantum systems in three-level and four-level configurations are calculated using the shooting method, while optical properties are obtained using the density matrix formalism and master equations. It is shown that peaks of the optical properties experience a blue-shift with increasing hydrostatic pressure and red-shift with increasing temperature. The changes of optical properties as a consequence of changes in barrier wells widths are non-monotonic, and these changes are discussed in detail.

Optical equivalence of isotropic ensembles of ellipsoidal particles in the Rayleigh-Gans-Debye and anomalous diffraction approximations and its consequences

NASA Astrophysics Data System (ADS)

Paramonov, L. E.

2012-05-01

Light scattering by isotropic ensembles of ellipsoidal particles is considered in the Rayleigh-Gans-Debye approximation. It is proved that randomly oriented ellipsoidal particles are optically equivalent to polydisperse randomly oriented spheroidal particles and polydisperse spherical particles. Density functions of the shape and size distributions for equivalent ensembles of spheroidal and spherical particles are presented. In the anomalous diffraction approximation, equivalent ensembles of particles are shown to also have equal extinction, scattering, and absorption coefficients. Consequences of optical equivalence are considered. The results are illustrated by numerical calculations of the angular dependence of the scattering phase function using the T-matrix method and the Mie theory.

Optofluidic lens with tunable focal length and asphericity

PubMed Central

Mishra, Kartikeya; Murade, Chandrashekhar; Carreel, Bruno; Roghair, Ivo; Oh, Jung Min; Manukyan, Gor; van den Ende, Dirk; Mugele, Frieder

2014-01-01

Adaptive micro-lenses enable the design of very compact optical systems with tunable imaging properties. Conventional adaptive micro-lenses suffer from substantial spherical aberration that compromises the optical performance of the system. Here, we introduce a novel concept of liquid micro-lenses with superior imaging performance that allows for simultaneous and independent tuning of both focal length and asphericity. This is achieved by varying both hydrostatic pressures and electric fields to control the shape of the refracting interface between an electrically conductive lens fluid and a non-conductive ambient fluid. Continuous variation from spherical interfaces at zero electric field to hyperbolic ones with variable ellipticity for finite fields gives access to lenses with positive, zero, and negative spherical aberration (while the focal length can be tuned via the hydrostatic pressure). PMID:25224851

Expressions for the spherical-wave-structure function based on a bump spectrum model for the index of refraction

NASA Astrophysics Data System (ADS)

Richardson, Christina E.; Andrews, Larry C.

1991-07-01

New spectra models have recently been developed for the spatial power spectra of temperature and refractive index fluctuations in the atmospheric boundary layer showing the characteristic 'bump' just prior to the dissipation ranges. Theoretical work involving these new models has led to new expressions for the phase structure function associated with a plane optical wave, although most experimental work has involved spherical waves. Following techniques similar to those used for the plane wave analysis, new expressions valid in geometrical and diffraction regimes are developed here for the phase structure function of a spherical optical wave propagating through clear-air atmospheric turbulence. Useful asymptotic formulas for small separation distances and the inertial subrange are derived from these general expressions.

Innovative hybrid optics: combining the thermal stability of glass with low manufacturing cost of polymers

NASA Astrophysics Data System (ADS)

Doushkina, Valentina

2010-08-01

Innovative hybrid glass-polymer optical solutions on a component, module, or system level offer thermal stability of glass with low manufacturing cost of polymers reducing component weight, enhancing the safety and appeal of the products. Narrow choice of polymer materials is compensated by utilizing sophisticated optical surfaces such as refractive, reflective, and diffractive substrates with spherical, aspherical, cylindrical, and freeform prescriptions. Current advancements in polymer technology and injection molding capabilities placed polymer optics in the heart of many high tech devices and applications including Automotive Industry, Defense & Aerospace; Medical/Bio Science; Projection Displays, Sensors, Information Technology, Commercial and Industrial. This paper is about integration of polymer and glass optics for enhanced optical performance with reduced number of components, thermal stability, and low manufacturing cost. The listed advantages are not achievable when polymers or glass optics are used as stand-alone. The author demonstrates that integration of polymer and glass on component or optical system level on one hand offers high resolution and diffraction limited image quality, similar to the glass optics with stable refractive index and stable thermal performance when design is athermalized within the temperature range. On the other hand, the integrated hybrid solution significantly reduces cost, weight, and complexity, just like the polymer optics. The author will describe the design and analyzes process of combining glass and polymer optics for variety of challenging applications such as fast optics with low F/#, wide field of view lenses or systems, free form optics, etc.

Biocular vehicle display optical designs

NASA Astrophysics Data System (ADS)

Chu, H.; Carter, Tom

2012-06-01

Biocular vehicle display optics is a fast collimating lens (f / # < 0.9) that presents the image of the display at infinity to both eyes of the viewer. Each eye captures the scene independently and the brain merges the two images into one through the overlapping portions of the images. With the recent conversion from analog CRT based displays to lighter, more compact active-matrix organic light-emitting diodes (AMOLED) digital image sources, display optical designs have evolved to take advantage of the higher resolution AMOLED image sources. To maximize the field of view of the display optics and fully resolve the smaller pixels, the digital image source is pre-magnified by relay optics or a coherent taper fiber optics plate. Coherent taper fiber optics plates are used extensively to: 1. Convert plano focal planes to spherical focal planes in order to eliminate Petzval field curvature. This elimination enables faster lens speed and/or larger field of view of eye pieces, display optics. 2. Provide pre-magnification to lighten the work load of the optics to further increase the numerical aperture and/or field of view. 3. Improve light flux collection efficiency and field of view by collecting all the light emitted by the image source and guiding imaging light bundles toward the lens aperture stop. 4. Reduce complexity of the optical design and overall packaging volume by replacing pre-magnification optics with a compact taper fiber optics plate. This paper will review and compare the performance of biocular vehicle display designs without and with taper fiber optics plate.

Optical and Biometric Characteristics of Anisomyopia in Human Adults

PubMed Central

Tian, Yibin; Tarrant, Janice; Wildsoet, Christine F.

2011-01-01

Purpose To investigate the role of higher order optical aberrations and thus retinal image degradation in the development of myopia, through the characterization of anisomyopia in human adults in terms of their optical and biometric characteristics. Methods The following data were collected from both eyes of fifteen young adult anisometropic myopes and sixteen isometropic myopes: subjective and objective refractive errors, corneal power and shape, monochromatic optical aberrations, anterior chamber depth, lens thickness, vitreous chamber depth, and best corrected visual acuity. Monochromatic aberrations were analyzed in terms of their higher order components, and further analyzed in terms of 31 optical quality metrics. Interocular differences for the two groups (anisomyopes vs. isomyopes) were compared and the relationship between measured ocular parameters and refractive errors also analyzed across all eyes. Results As expected, anisomyopes and isomyopes differed significantly in terms of interocular differences in vitreous chamber depth, axial length and refractive error. However, interocular differences in other optical properties showed no significant intergroup differences. Overall, higher myopia was associated with deeper anterior and vitreous chambers, higher astigmatism, more prolate corneas, and more positive spherical aberration. Other measured optical and biometric parameters were not significantly correlated with spherical refractive error, although some optical quality metrics and corneal astigmatism were significantly correlated with refractive astigmatism. Conclusions An optical cause for anisomyopia related to increased higher order aberrations is not supported by our data. Corneal shape changes and increased astigmatism in more myopic eyes may be a by-product of the increased anterior chamber growth in these eyes; likewise, the increased positive spherical aberration in more myopic eyes may be a product of myopic eye growth. PMID:21797915

Aplanatic double reflection system for thermophotovoltaic applications: design.

PubMed

Demichelis, F; Ferrari, G; Minetti-Mezzetti, E

1981-12-15

The design of a solar concentrator is presented; it consists of a spherical mirror and a field of Fresnel mirror facets deployed on a spherical surface so that sine condition is satisfied, eliminating both spherical aberration and coma. This particular easy to construct optical system yields high concentration ratios and has the distinct advantage of having a narrow beam aperture near the receiver. These design features make the concentrator particularly suitable for thermophotovoltaic applications.

Electron impact ionization of cycloalkanes, aldehydes, and ketones

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Dhanoj; Antony, Bobby, E-mail: bka.ism@gmail.com

The theoretical calculations of electron impact total ionization cross section for cycloalkane, aldehyde, and ketone group molecules are undertaken from ionization threshold to 2 keV. The present calculations are based on the spherical complex optical potential formalism and complex scattering potential ionization contribution method. The results of most of the targets studied compare fairly well with the recent measurements, wherever available and the cross sections for many targets are predicted for the first time. The correlation between the peak of ionization cross sections with number of target electrons and target parameters is also reported. It was found that the crossmore » sections at their maximum depend linearly with the number of target electrons and with other target parameters, confirming the consistency of the values reported here.« less

Cadmium sulphide (CdS) thin films deposited by chemical bath deposition (CBD) and dip coating techniques—a comparative study

NASA Astrophysics Data System (ADS)

Khimani, Ankurkumar J.; Chaki, Sunil H.; Malek, Tasmira J.; Tailor, Jiten P.; Chauhan, Sanjaysinh M.; Deshpande, M. P.

2018-03-01

The CdS thin films were deposited on glass slide substrates by Chemical Bath Deposition and dip coating techniques. The films thickness variation with deposition time showed maximum films deposition at 35 min for both the films. The energy dispersive analysis of x-ray showed both the films to be stoichiometric. The x-ray diffraction analysis confirmed the films possess hexagonal crystal structure. The transmission electron, scanning electron and optical microscopy study showed the films deposition to be uniform. The selected area electron diffraction exhibited ring patterns stating the films to be polycrystalline in nature. The atomic force microscopy images showed surface formed of spherical grains, hills and valleys. The recorded optical absorbance spectra analysis revealed the films possess direct optical bandgap having values of 2.25 eV for CBD and 2.40 eV for dip coating. The refractive index (η), extinction coefficient (k), complex dielectric constant (ε) and optical conductivity (σ 0) variation with wavelength showed maximum photon absorption till the respective wavelengths corresponding to the optical bandgap energy values. The recorded photoluminescence spectra showed two emission peaks. All the obtained results have been discussed in details.

Design of an imaging microscope for soft X-ray applications

NASA Astrophysics Data System (ADS)

Hoover, Richard B.; Shealy, David L.; Gabardi, David R.; Walker, Arthur B. C., Jr.; Lindblom, Joakim F.

1988-01-01

An imaging soft X-ray microscope with a spatial resolution of 0.1 micron and normal incidence multilayer optics is discussed. The microscope has a Schwarzschild configuration, which consists of two concentric spherical mirrors with radii of curvature which minimize third-order spherical aberration, coma, and astigmatism. The performance of the Stanford/MSFC Cassegrain X-ray telescope and its relevance to the present microscope are addressed. A ray tracing analysis of the optical system indicates that diffraction-limited performance can be expected for an object height of 0.2 mm.

Wollaston prism phase-stepping point diffraction interferometer and method

DOEpatents

Rushford, Michael C.

2004-10-12

A Wollaston prism phase-stepping point diffraction interferometer for testing a test optic. The Wollaston prism shears light into reference and signal beams, and provides phase stepping at increased accuracy by translating the Wollaston prism in a lateral direction with respect to the optical path. The reference beam produced by the Wollaston prism is directed through a pinhole of a diaphragm to produce a perfect spherical reference wave. The spherical reference wave is recombined with the signal beam to produce an interference fringe pattern of greater accuracy.

Potential Sources of Polarized Light from a Plant Canopy

NASA Technical Reports Server (NTRS)

Vanderbilt, Vern; Daughtry, Craig; Dahlgren, Robert

2016-01-01

Field measurements have demonstrated that sunlight polarized during a first surface reflection by shiny leaves dominates the optical polarization of the light reflected by shiny-leafed plant canopies having approximately spherical leaf angle probability density functions ("Leaf Angle Distributions" - LAD). Yet for other canopies - specifically those without shiny leaves and/or spherical LADs - potential sources of optically polarized light may not always be obvious. Here we identify possible sources of polarized light within those other canopies and speculate on the ecologically important information polarization measurements of those sources might contain.

The effects of temperature, hydrostatic pressure and size on optical gain for GaAs spherical quantum dot laser with hydrogen impurity

NASA Astrophysics Data System (ADS)

Owji, Erfan; Keshavarz, Alireza; Mokhtari, Hosein

2016-10-01

In this paper, the effects of temperature, hydrostatic pressure and size on optical gain for GaAs spherical quantum dot laser with hydrogen impurity are investigated. For this purpose, the effects of temperature, pressure and quantum dot size on the band gap energy, effective mass, and dielectric constant are studied. The eigenenergies and eigenstates for valence and conduction band are calculated by using Runge-Kutta numerical method. Results show that changes in the temperature, pressure and size lead to the alteration of the band gap energy and effective mass. Also, increasing the temperature redshifts the optical gain peak and at special temperature ranges lead to increasing or decreasing of it. Further, by reducing the size, temperature-dependent of optical gain is decreased. Additionally, enhancing of the hydrostatic pressure blueshifts the peak of optical gain, and its behavior as a function of pressure which depends on the size. Finally, increasing the radius rises the redshifts of the peak of optical gain.

The effects of a geometrical size, external electric fields and impurity on the optical gain of a quantum dot laser with a semi-parabolic spherical well potential

NASA Astrophysics Data System (ADS)

Owji, Erfan; Keshavarz, Alireza; Mokhtari, Hosein

2017-03-01

In this paper, a GaAs / Alx Ga1-x As quantum dot laser with a semi-parabolic spherical well potential is assumed. By using Runge-Kutta method the eigenenergies and the eigenstates of valence and conduct bands are obtained. The effects of geometrical sizes, external electric fields and hydrogen impurity on the different electronic transitions of the optical gain are studied. The results show that the optical gain peak increases and red-shifts, by increasing the width of well or barrier, while more increasing of the width causes blue-shift and decreases it. The hydrogen impurity decreases the optical gain peak and blue-shifts it. Also, the increasing of the external electric fields cause to increase the peak of the optical gain, and (blue) red shift it. Finally, the optical gain for 1s-1s and 2s-1s transitions is prominent, while it is so weak for other transitions.

Linear and Nonlinear Optical Properties of Spherical Quantum Dots: Effects of Hydrogenic Impurity and Conduction Band Non-Parabolicity

NASA Astrophysics Data System (ADS)

Rezaei, G.; Vaseghi, B.; Doostimotlagh, N. A.

2012-03-01

Simultaneous effects of an on-center hydrogenic impurity and band edge non-parabolicity on intersubband optical absorption coefficients and refractive index changes of a typical GaAs/AlxGa1-x As spherical quantum dot are theoretically investigated, using the Luttinger—Kohn effective mass equation. So, electronic structure and optical properties of the system are studied by means of the matrix diagonalization technique and compact density matrix approach, respectively. Finally, effects of an impurity, band edge non-parabolicity, incident light intensity and the dot size on the linear, the third-order nonlinear and the total optical absorption coefficients and refractive index changes are investigated. Our results indicate that, the magnitudes of these optical quantities increase and their peaks shift to higher energies as the influences of the impurity and the band edge non-parabolicity are considered. Moreover, incident light intensity and the dot size have considerable effects on the optical absorption coefficients and refractive index changes.

Light scattering by a nematic liquid crystal droplet: Wentzel–Kramers–Brillouin approximation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loiko, V. A., E-mail: loiko@dragon.bas-net.by; Konkolovich, A. V.; Miskevich, A. A.

2016-01-15

Light scattering by an optically anisotropic liquid crystal (LC) droplet of a nematic in an isotropic polymer matrix is considered in the Wentzel–Kramers–Brillouin (WKB) approximation. General relations are obtained for elements of the amplitude matrix of light scattering by a droplet of arbitrary shape and for the structure of the director field. Analytic expressions for the amplitude matrices are derived for spherical LC droplets with a uniformly oriented structure of local optical axes for strictly forward and strictly backward scattering. The efficiency factors of extinction and backward scattering for a spherical nonabsorbing LC droplet depending on the LC optical anisotropy,more » refractive index of the polymer, illumination conditions, and orientation of the optical axis of the droplet are analyzed. Verification of the obtained solutions has been performed.« less

Empirical Relationships Between Optical Properties and Equivalent Diameters of Fractal Soot Aggregates at 550 Nm Wavelength.

NASA Technical Reports Server (NTRS)

Pandey, Apoorva; Chakrabarty, Rajan K.; Liu, Li; Mishchenko, Michael I.

2015-01-01

Soot aggregates (SAs)-fractal clusters of small, spherical carbonaceous monomers-modulate the incoming visible solar radiation and contribute significantly to climate forcing. Experimentalists and climate modelers typically assume a spherical morphology for SAs when computing their optical properties, causing significant errors. Here, we calculate the optical properties of freshly-generated (fractal dimension Df = 1.8) and aged (Df = 2.6) SAs at 550 nm wavelength using the numericallyexact superposition T-Matrix method. These properties were expressed as functions of equivalent aerosol diameters as measured by contemporary aerosol instruments. This work improves upon previous efforts wherein SA optical properties were computed as a function of monomer number, rendering them unusable in practical applications. Future research will address the sensitivity of variation in refractive index, fractal prefactor, and monomer overlap of SAs on the reported empirical relationships.

Micrometric Control of the Optics of the Human Eye: Environment or Genes?

PubMed

Tabernero, Juan; Hervella, Lucía; Benito, Antonio; Colodro-Conde, Lucía; Ordoñana, Juan R; Ruiz-Sanchez, Marcos; Marín, José María; Artal, Pablo

2017-04-01

The human eye has typically more optical aberrations than conventional artificial optical systems. While the lower order modes (defocus and astigmatism) are well studied, our purpose is to explore the influence of genes versus the environment on the higher order aberrations of the optical components of the eye. We have performed a classical twin study in a sample from the Region of Murcia (Spain). Optical aberrations using a Hartmann-Shack sensor (AOnEye Voptica SL, Murcia, Spain) and corneal aberrations (using corneal topography data) were measured in 138 eyes corresponding to 69 twins; 36 monozygotic (MZ) and 33 dizygotic (DZ) pairs (age 55 years, SD 7 years). Intraclass correlation coefficients (ICCs) were used to estimate how strongly aberrations of twins resemble each other, and genetic models were fitted to quantify heritability in the selected phenotypes. Genes had a significant influence in the variance of most of the higher order aberration terms (heritability from 40% to 70%). This genetic influence was observed similarly in both cornea and complete eye aberrations. Additionally, the compensation factor of spherical aberration in the eye (i.e., how much corneal spherical aberration was compensated by internal spherical aberration) was found under genetic influence (heritability of 68%). There is a significant genetic contribution to the variance of aberrations of the eye, not only at macroscopic levels, as in myopia or astigmatism, but also at microscopic levels, where a few micrometers changes in surface topography can produce a large difference in the value of the optical aberrations.

Wide Angle, Color, Holographic Infinity Optics Display. Final Report.

ERIC Educational Resources Information Center

Magarinos, Jose R.; Coleman, Daniel J.

The project described demonstrated not only the feasibility of producing a holographic compound spherical beamspliter mirror with full color response, but the performance and color capabilities of such a beamsplitter when incorporated into a Pancake Window Display system as a replacement for the classical glass spherical beamsplitter. This…

Optical performance of toric intraocular lenses in the presence of decentration.

PubMed

Zhang, Bin; Ma, Jin-Xue; Liu, Dan-Yan; Du, Ying-Hua; Guo, Cong-Rong; Cui, Yue-Xian

2015-01-01

To evaluate the optical performance of toric intraocular lenses (IOLs) after decentration and with different pupil diameters, but with the IOL astigmatic axis aligned. Optical performances of toric T5 and SN60AT spherical IOLs after decentration were tested on a theoretical pseudophakic model eye based on the Hwey-Lan Liou schematic eye using the Zemax ray-tracing program. Changes in optical performance were analyzed in model eyes with 3-mm, 4-mm, and 5-mm pupil diameters and decentered from 0.25 mm to 0.75 mm with an interval of 5° at the meridian direction from 0° to 90°. The ratio of the modulation transfer function (MTF) between a decentered and a centered IOL (MTFDecentration/MTFCentration) was calculated to analyze the decrease in optical performance. Optical performance of the toric IOL remained unchanged when IOLs were decentered in any meridian direction. The MTFs of the two IOLs decreased, whereas optical performance remained equivalent after decentration. The MTFDecentration/MTFCentration ratios of the IOLs at a decentration from 0.25 mm to 0.75 mm were comparable in the toric and SN60AT IOLs. After decentration, MTF decreased further, with the MTF of the toric IOL being slightly lower than that of the SN60AT IOL. Imaging qualities of the two IOLs decreased when the pupil diameter and the degree of decentration increased, but the decrease was similar in the toric and spherical IOLs. Toric IOLs were comparable to spherical IOLs in terms of tolerance to decentration at the correct axial position.

Optical performance of toric intraocular lenses in the presence of decentration

PubMed Central

Zhang, Bin; Ma, Jin-Xue; Liu, Dan-Yan; Du, Ying-Hua; Guo, Cong-Rong; Cui, Yue-Xian

2015-01-01

AIM To evaluate the optical performance of toric intraocular lenses (IOLs) after decentration and with different pupil diameters, but with the IOL astigmatic axis aligned. METHODS Optical performances of toric T5 and SN60AT spherical IOLs after decentration were tested on a theoretical pseudophakic model eye based on the Hwey-Lan Liou schematic eye using the Zemax ray-tracing program. Changes in optical performance were analyzed in model eyes with 3-mm, 4-mm, and 5-mm pupil diameters and decentered from 0.25 mm to 0.75 mm with an interval of 5° at the meridian direction from 0° to 90°. The ratio of the modulation transfer function (MTF) between a decentered and a centered IOL (MTFDecentration/MTFCentration) was calculated to analyze the decrease in optical performance. RESULTS Optical performance of the toric IOL remained unchanged when IOLs were decentered in any meridian direction. The MTFs of the two IOLs decreased, whereas optical performance remained equivalent after decentration. The MTFDecentration/MTFCentration ratios of the IOLs at a decentration from 0.25 mm to 0.75 mm were comparable in the toric and SN60AT IOLs. After decentration, MTF decreased further, with the MTF of the toric IOL being slightly lower than that of the SN60AT IOL. Imaging qualities of the two IOLs decreased when the pupil diameter and the degree of decentration increased, but the decrease was similar in the toric and spherical IOLs. CONCLUSIONS Toric IOLs were comparable to spherical IOLs in terms of tolerance to decentration at the correct axial position. PMID:26309871

Impact of Primary Spherical Aberration, Spatial Frequency and Stiles Crawford Apodization on Wavefront determined Refractive Error: A Computational Study

PubMed Central

Xu, Renfeng; Bradley, Arthur; Thibos, Larry N.

2013-01-01

Purpose We tested the hypothesis that pupil apodization is the basis for central pupil bias of spherical refractions in eyes with spherical aberration. Methods We employed Fourier computational optics in which we vary spherical aberration levels, pupil size, and pupil apodization (Stiles Crawford Effect) within the pupil function, from which point spread functions and optical transfer functions were computed. Through-focus analysis determined the refractive correction that optimized retinal image quality. Results For a large pupil (7 mm), as spherical aberration levels increase, refractions that optimize the visual Strehl ratio mirror refractions that maximize high spatial frequency modulation in the image and both focus a near paraxial region of the pupil. These refractions are not affected by Stiles Crawford Effect apodization. Refractions that optimize low spatial frequency modulation come close to minimizing wavefront RMS, and vary with level of spherical aberration and Stiles Crawford Effect. In the presence of significant levels of spherical aberration (e.g. C40 = 0.4 µm, 7mm pupil), low spatial frequency refractions can induce −0.7D myopic shift compared to high SF refraction, and refractions that maximize image contrast of a 3 cycle per degree square-wave grating can cause −0.75D myopic drift relative to refractions that maximize image sharpness. Discussion Because of small depth of focus associated with high spatial frequency stimuli, the large change in dioptric power across the pupil caused by spherical aberration limits the effective aperture contributing to the image of high spatial frequencies. Thus, when imaging high spatial frequencies, spherical aberration effectively induces an annular aperture defining that portion of the pupil contributing to a well-focused image. As spherical focus is manipulated during the refraction procedure, the dimensions of the annular aperture change. Image quality is maximized when the inner radius of the induced annulus falls to zero, thus defining a circular near paraxial region of the pupil that determines refraction outcome. PMID:23683093

Characterization of individual complex particles in urban atmospheric environment

NASA Astrophysics Data System (ADS)

Suzuki, K.; Takii, T.; Tomiyasu, B.; Nihei, Y.

2006-07-01

The origins of carrier particles of complex particles (iron-rich particles) collected from the urban atmospheric environment near to road traffic and a railroad were investigated from the detailed surface information using FE-SEM/EDS and TOF-SIMS analyses. From the FE-SEM/EDS analyses, the iron-rich particles were classified into two typical types (spherical type and non-spherical type). From the TOF-SIMS measurements, the characteristic secondary ions of spherical type of iron-rich particles were 23Na + and 39K +. The minor components of non-spherical type were Al, Ca and Ba. On the other hand, we carried out TOF-SIMS measurement to materials of rail origin and brake origin. From the comparison of these spectra pattern, it seemed that the spherical type of iron-rich particles was emitted from the rail origin. We concluded that the origin of non-spherical type of iron-rich particles were brake pad of vehicles.

Power profiles of single vision and multifocal soft contact lenses.

PubMed

Wagner, Sandra; Conrad, Fabian; Bakaraju, Ravi C; Fedtke, Cathleen; Ehrmann, Klaus; Holden, Brien A

2015-02-01

The purpose of this study was to investigate the optical zone power profile of the most commonly prescribed soft contact lenses to assess their potential impact on peripheral refractive error and hence myopia progression. The optical power profiles of six single vision and ten multifocal contact lenses of five manufacturers in the powers -1.00 D, -3.00 D, and -6.00 D were measured using the SHSOphthalmic (Optocraft GmbH, Erlangen, Germany). Instrument repeatability was also investigated. Instrument repeatability was dependent on the distance from the optical centre, manifesting unreliable data for the central 1mm of the optic zone. Single vision contact lens measurements of -6.00 D lenses revealed omafilcon A having the most negative spherical aberration, lotrafilcon A having the least. Somofilcon A had the highest minus power and lotrafilcon A the biggest deviation in positive direction, relative to their respective labelled powers. Negative spherical aberration occurred for almost all of the multifocal contact lenses, including the centre-distance designs etafilcon A bifocal and omafilcon A multifocal. Lotrafilcon B and balafilcon A seem to rely predominantly on the spherical aberration component to provide multifocality. Power profiles of single vision soft contact lenses varied greatly, many having a negative spherical aberration profile that would exacerbate myopia. Some lens types and powers are affected by large intra-batch variability or power offsets of more than 0.25 dioptres. Evaluation of power profiles of multifocal lenses was derived that provides helpful information for prescribing lenses for presbyopes and progressing myopes. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Continuous-feed optical sorting of aerosol particles

PubMed Central

Curry, J. J.; Levine, Zachary H.

2016-01-01

We consider the problem of sorting, by size, spherical particles of order 100 nm radius. The scheme we analyze consists of a heterogeneous stream of spherical particles flowing at an oblique angle across an optical Gaussian mode standing wave. Sorting is achieved by the combined spatial and size dependencies of the optical force. Particles of all sizes enter the flow at a point, but exit at different locations depending on size. Exiting particles may be detected optically or separated for further processing. The scheme has the advantages of accommodating a high throughput, producing a continuous stream of continuously dispersed particles, and exhibiting excellent size resolution. We performed detailed Monte Carlo simulations of particle trajectories through the optical field under the influence of convective air flow. We also developed a method for deriving effective velocities and diffusion constants from the Fokker-Planck equation that can generate equivalent results much more quickly. With an optical wavelength of 1064 nm, polystyrene particles with radii in the neighborhood of 275 nm, for which the optical force vanishes, may be sorted with a resolution below 1 nm. PMID:27410570

Sensitivity of corneal biomechanical and optical behavior to material parameters using design of experiments method.

PubMed

Xu, Mengchen; Lerner, Amy L; Funkenbusch, Paul D; Richhariya, Ashutosh; Yoon, Geunyoung

2018-02-01

The optical performance of the human cornea under intraocular pressure (IOP) is the result of complex material properties and their interactions. The measurement of the numerous material parameters that define this material behavior may be key in the refinement of patient-specific models. The goal of this study was to investigate the relative contribution of these parameters to the biomechanical and optical responses of human cornea predicted by a widely accepted anisotropic hyperelastic finite element model, with regional variations in the alignment of fibers. Design of experiments methods were used to quantify the relative importance of material properties including matrix stiffness, fiber stiffness, fiber nonlinearity and fiber dispersion under physiological IOP. Our sensitivity results showed that corneal apical displacement was influenced nearly evenly by matrix stiffness, fiber stiffness and nonlinearity. However, the variations in corneal optical aberrations (refractive power and spherical aberration) were primarily dependent on the value of the matrix stiffness. The optical aberrations predicted by variations in this material parameter were sufficiently large to predict clinically important changes in retinal image quality. Therefore, well-characterized individual variations in matrix stiffness could be critical in cornea modeling in order to reliably predict optical behavior under different IOPs or after corneal surgery.

Optical system

NASA Technical Reports Server (NTRS)

Breckinridge, J. B.; Page, N. A.; Shack, R. V.; Shannon, R. R. (Inventor)

1985-01-01

Disclosed is an otpical system used in a spacecraft to observe a remote surface and provide a spatial and spectral image of this surface. The optical system includes aspheric and spherical mirrors aligned to focus at a first focal plane an image of the surface, and a mirror at this first focal plane which reflects light back on to the spherical mirror. This spherical mirror collimates the light and directs it through a prism which disperses it. The dispersed light is then focused on an array of light responsive elements disposed at a second focal plane. The prism is designed such that it disperses light into components of different wavelengths, with the components of shorter wavelengths being dispersed more than the components of longer wavelengths to present at the second focal plane a distribution pattern in which preselected groupings of the components are dispersed over essentially equal spacing intervals.

Particle-based optical pressure sensors for 3D pressure mapping.

PubMed

Banerjee, Niladri; Xie, Yan; Chalaseni, Sandeep; Mastrangelo, Carlos H

2015-10-01

This paper presents particle-based optical pressure sensors for in-flow pressure sensing, especially for microfluidic environments. Three generations of pressure sensitive particles have been developed- flat planar particles, particles with integrated retroreflectors and spherical microballoon particles. The first two versions suffer from pressure measurement dependence on particles orientation in 3D space and angle of interrogation. The third generation of microspherical particles with spherical symmetry solves these problems making particle-based manometry in microfluidic environment a viable and efficient methodology. Static and dynamic pressure measurements have been performed in liquid medium for long periods of time in a pressure range of atmospheric to 40 psi. Spherical particles with radius of 12 μm and balloon-wall thickness of 0.5 μm are effective for more than 5 h in this pressure range with an error of less than 5%.

Synthesis and Study of Optical Characteristics of Ti0.91O2/CdS Hybrid Sphere Structures

NASA Astrophysics Data System (ADS)

Kong, Lingbin; Xu, Qinfeng; Zhang, Meng; Wang, Dehua; Liu, Mingliang; Zhang, Lei; Jiao, Mengmeng; Wang, Honggang; Yang, Chuanlu

2018-03-01

The optical properties of alternating ultrathin Ti0.91O2 nanosheets and CdS nanoparticle hybrid spherical structures designed by the layer-by-layer (LBL) assembly technique are investigated. From the photoluminescence (PL) spectral measurements on the hybrid spherical structures, a spectrum-shifted fluorescence emission occurs in this novel hybrid material. The time-resolved PL measurements exhibit a remarkably increased PL lifetime of 3.75 ns compared with only Ti0.91O2 spheres or CdS nanoparticles. The novel results were attributed to the enhanced electron-hole separation due to the new type II indirect optical transition mechanism between Ti0.91O2 and CdS in a charge-separated configuration.

Transition operators in electromagnetic-wave diffraction theory. II - Applications to optics

NASA Technical Reports Server (NTRS)

Hahne, G. E.

1993-01-01

The theory developed by Hahne (1992) for the diffraction of time-harmonic electromagnetic waves from fixed obstacles is briefly summarized and extended. Applications of the theory are considered which comprise, first, a spherical harmonic expansion of the so-called radiation impedance operator in the theory, for a spherical surface, and second, a reconsideration of familiar short-wavelength approximation from the new standpoint, including a derivation of the so-called physical optics method on the basis of quasi-planar approximation to the radiation impedance operator, augmented by the method of stationary phase. The latter includes a rederivation of the geometrical optics approximation for the complete Green's function for the electromagnetic field in the presence of a smooth- and a convex-surfaced perfectly electrically conductive obstacle.

Contribution of the gradient refractive index and shape to the crystalline lens spherical aberration and astigmatism.

PubMed

Birkenfeld, Judith; de Castro, Alberto; Ortiz, Sergio; Pascual, Daniel; Marcos, Susana

2013-06-28

The optical properties of the crystalline lens are determined by its shape and refractive index distribution. However, to date, those properties have not been measured together in the same lens, and therefore their relative contributions to optical aberrations are not fully understood. The shape, the optical path difference, and the focal length of ten porcine lenses (age around 6 months) were measured in vitro using Optical Coherence Tomography and laser ray tracing. The 3D Gradient Refractive Index distribution (GRIN) was reconstructed by means of an optimization method based on genetic algorithms. The optimization method searched for the parameters of a 4-variable GRIN model that best fits the distorted posterior surface of the lens in 18 different meridians. Spherical aberration and astigmatism of the lenses were estimated using computational ray tracing, with the reconstructed GRIN lens and an equivalent homogeneous refractive index. For all lenses the posterior radius of curvature was systematically steeper than the anterior one, and the conic constant of both the anterior and posterior positive surfaces was positive. In average, the measured focal length increased with increasing pupil diameter, consistent with a crystalline lens negative spherical aberration. The refractive index of nucleus and surface was reconstructed to an average value of 1.427 and 1.364, respectively, for 633 nm. The results of the GRIN reconstruction showed a wide distribution of the index in all lens samples. The GRIN shifted spherical aberration towards negative values when compared to a homogeneous index. A negative spherical aberration with GRIN was found in 8 of the 10 lenses. The presence of GRIN also produced a decrease in the total amount of lens astigmatism in most lenses, while the axis of astigmatism was only little influenced by the presence of GRIN. To our knowledge, this study is the first systematic experimental study of the relative contribution of geometry and GRIN to the aberrations in a mammal lens. Copyright © 2013 Elsevier Ltd. All rights reserved.

Characterizations of individual human red blood cells from patients with diabetes mellitus (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lee, SangYun; Jang, Seongsoo; Park, HyunJoo; Park, YongKeun

2016-03-01

We systematically measure the morphological, biochemical, and biomechanical properties of individual human red blood cells (RBCs) from patients with diabetes mellitus using quantitative phase imaging technique to characterize the diabetic red cells with respect to those of the healthy. The 3-D refractive index tomograms and 2-D dynamic membrane fluctuation maps of individual RBCs are reconstructed from a set of the retrieved complex optical fields at various laser incidence angles using the Common-path diffraction optical tomography, from which volume, surface area, sphericity, hemoglobin (Hb) concentration, Hb content, and membrane fluctuation are obtained simultaneously. The correlative relations among the retrieved red cell indices of diabetic and healthy RBCs are also investigated with capabilities of individual cell measurement. As expected, there are no significant alterations in morphologies (cellular volumes, surface area, and sphericity) between diabetic and healthy RBCs. However, despite the minute mean corpuscular Hb differences in cell blood count datasheet, the measured Hb concentrations and Hb contents of diabetic RBCs are statistically higher than those of healthy RBCs, which might be related to the glycation of Hb molecules by hyperglycemia. Meanwhile, the membrane fluctuations of diabetic RBCs are clearly diminished compared to healthy red cells, implying the significantly decreased RBC deformability. In particular, it seems that the membrane fluctuations have mild negative relationships with the reported HbA1c levels.

Spherical Coordinate Systems for Streamlining Suited Mobility Analysis

NASA Technical Reports Server (NTRS)

Benson, Elizabeth; Cowley, Matthew S.; Harvill. Lauren; Rajulu, Sudhakar

2014-01-01

When describing human motion, biomechanists generally report joint angles in terms of Euler angle rotation sequences. However, there are known limitations in using this method to describe complex motions such as the shoulder joint during a baseball pitch. Euler angle notation uses a series of three rotations about an axis where each rotation is dependent upon the preceding rotation. As such, the Euler angles need to be regarded as a set to get accurate angle information. Unfortunately, it is often difficult to visualize and understand these complex motion representations. One of our key functions is to help design engineers understand how a human will perform with new designs and all too often traditional use of Euler rotations becomes as much of a hindrance as a help. It is believed that using a spherical coordinate system will allow ABF personnel to more quickly and easily transmit important mobility data to engineers, in a format that is readily understandable and directly translatable to their design efforts. Objectives: The goal of this project is to establish new analysis and visualization techniques to aid in the examination and comprehension of complex motions. Methods: This project consisted of a series of small sub-projects, meant to validate and verify the method before it was implemented in the ABF's data analysis practices. The first stage was a proof of concept, where a mechanical test rig was built and instrumented with an inclinometer, so that its angle from horizontal was known. The test rig was tracked in 3D using an optical motion capture system, and its position and orientation were reported in both Euler and spherical reference systems. The rig was meant to simulate flexion/extension, transverse rotation and abduction/adduction of the human shoulder, but without the variability inherent in human motion. In the second phase of the project, the ABF estimated the error inherent in a spherical coordinate system, and evaluated how this error would vary within the reference frame. This stage also involved expanding a kinematic model of the shoulder, to include the torso, knees, ankle, elbows, wrists and neck. Part of this update included adding a representation of 'roll' about an axis, for upper arm and lower leg rotations. The third stage of the project involved creating visualization methods to assist in interpreting motion in a spherical frame. This visualization method will be incorporated in a tool to evaluate a database of suited mobility data, which is currently in development.

Structured light stereo catadioptric scanner based on a spherical mirror

NASA Astrophysics Data System (ADS)

Barone, S.; Neri, P.; Paoli, A.; Razionale, A. V.

2018-08-01

The present paper describes the development and characterization of a structured light stereo catadioptric scanner for the omnidirectional reconstruction of internal surfaces. The proposed approach integrates two digital cameras, a multimedia projector and a spherical mirror, which is used to project the structured light patterns generated by the light emitter and, at the same time, to reflect into the cameras the modulated fringe patterns diffused from the target surface. The adopted optical setup defines a non-central catadioptric system, thus relaxing any geometrical constraint in the relative placement between optical devices. An analytical solution for the reflection on a spherical surface is proposed with the aim at modelling forward and backward projection tasks for a non-central catadioptric setup. The feasibility of the proposed active catadioptric scanner has been verified by reconstructing various target surfaces. Results demonstrated a great influence of the target surface distance from the mirror's centre on the measurement accuracy. The adopted optical configuration allows the definition of a metrological 3D scanner for surfaces disposed within 120 mm from the mirror centre.

Testing large flats with computer generated holograms

NASA Astrophysics Data System (ADS)

Pariani, Giorgio; Tresoldi, Daniela; Spanò, Paolo; Bianco, Andrea

2012-09-01

We describe the optical test of a large flat based on a spherical mirror and a dedicated CGH. The spherical mirror, which can be accurately manufactured and tested in absolute way, allows to obtain a quasi collimated light beam, and the hologram performs the residual wavefront correction. Alignment tools for the spherical mirror and the hologram itself are encoded in the CGH. Sensitivity to fabrication errors and alignment has been evaluated. Tests to verify the effectiveness of our approach are now under execution.

Tuning the morphology of metastable MnS films by simple chemical bath deposition technique

NASA Astrophysics Data System (ADS)

Dhandayuthapani, T.; Girish, M.; Sivakumar, R.; Sanjeeviraja, C.; Gopalakrishnan, R.

2015-10-01

In the present investigation, we have prepared the spherical particles, almond-like, and cauliflower-like morphological structures of metastable MnS films on glass substrate by chemical bath deposition technique at low temperature without using any complexing or chelating agent. The morphological change of MnS films with molar ratio may be due to the oriented aggregation of adjacent particles. The compositional purity of deposited film was confirmed by the EDAX study. X-ray diffraction and micro-Raman studies confirm the sulfur source concentration induced enhancement in the crystallization of films with metastable MnS phase (zinc-blende β-MnS, and wurtzite γ-MnS). The shift in PL emission peak with molar ratio may be due to the change in optical energy band gap of the MnS, which was further confirmed by the optical absorbance study. The paramagnetic behavior of the sample was confirmed by the M-H plot.

Deep-turbulence wavefront sensing using digital holography in the on-axis phase shifting recording geometry

NASA Astrophysics Data System (ADS)

Thornton, Douglas E.; Spencer, Mark F.; Perram, Glen P.

2017-09-01

The effects of deep turbulence in long-range imaging applications presents unique challenges to properly measure and correct for aberrations incurred along the atmospheric path. In practice, digital holography can detect the path-integrated wavefront distortions caused by deep turbulence, and di erent recording geometries offer different benefits depending on the application of interest. Previous studies have evaluated the performance of the off-axis image and pupil plane recording geometries for deep-turbulence sensing. This study models digital holography in the on-axis phase shifting recording geometry using wave optics simulations. In particular, the analysis models spherical-wave propagation through varying deep-turbulence conditions to estimate the complex optical field, and performance is evaluated by calculating the field-estimated Strehl ratio and RMS wavefront error. Altogether, the results show that digital holography in the on-axis phase shifting recording geometry is an effective wavefront-sensing method in the presence of deep turbulence.

Folded-path optical analysis gas cell

DOEpatents

Carangelo, R.M.; Wright, D.D.

1995-08-08

A folded-path gas cell employs an elliptical concave mirror in confronting relationship to two substantially spherical concave mirrors. At least one of the spherical mirrors, and usually both, are formed with an added cylindrical component to increase orthogonal foci coincidence and thereby to increase the radiation energy throughput characteristic of the cell. 10 figs.

Amplitude-phase characteristics of electromagnetic fields diffracted by a hole in a thin film with realistic optical properties

NASA Astrophysics Data System (ADS)

Dorofeyev, Illarion

2009-03-01

Characteristics of a quasi-spherical wave front of an electromagnetic field diffracted by a subwavelength hole in a thin film with real optical properties are studied. Related diffraction problem is solved in general by use of the scalar and vector Green's theorems and related Green's function of a boundary-value problem. Local phase deviations of a diffracted wave front from an ideal spherical front are calculated. Diffracted patterns are calculated for the coherent incident fields in case of holes array in a screen of perfect conductivity.

Optical design with Wood lenses

NASA Astrophysics Data System (ADS)

Caldwell, J. Brian

1991-01-01

Spherical aberration in a flat surfaced radial gradient-index lens (a Wood lens) with a parabolic index profile can be corrected by altering the profile to Include higher order terms. However this results in a large amowfl of third order coma. This paper presents an alternative method of aberration correction similar to that used in the catadiopthc Schmidtsystem. A Wood lens with a parabolic profile is used to provide all or most of the optical power. Coma is corrected by stop shifting and Spherical aberration is corrected by placing a powerless Wood lens corrector plate at the stop. 1.

Plasmonic nanoparticles for a bottom-up approach to fabricate optical metamaterials

NASA Astrophysics Data System (ADS)

Dintinger, José; Scharf, Toralf

2012-03-01

We investigate experimentally metallic nanoparticle composites fabricated by bottom-up techniques as potential candidates for optical metamaterials. Depending on the plasmonic resonances sustained by individual NPs and their nanoscale organization into larger meta-atoms, various properties might emerge. Here, the focus of our contribution is on the fabrication and optical characterization of silver NP clusters with a spherical shape. We start with the characterisation of the "bulk" dielectric constants of silver NP inks by spectroscopic ellipsometry for different nanoparticle densities (i.e from strongly diluted dispersions to solid randomly packed films). The inks are then used to prepare spherical nanoparticle clusters by an oil-in water emulsion technique. The study of their optical properties demonstrates their ability to support Mie resonances in the visible. These resonances are associated with the excitation of a magnetic dipole, which constitutes a prerequisite to the realization of metamaterials with negative permeability.

Extension of geometrical-optics approximation to on-axis Gaussian beam scattering. I. By a spherical particle.

PubMed

Xu, Feng; Ren, Kuan Fang; Cai, Xiaoshu

2006-07-10

The geometrical-optics approximation of light scattering by a transparent or absorbing spherical particle is extended from plane wave to Gaussian beam incidence. The formulas for the calculation of the phase of each ray and the divergence factor are revised, and the interference of all the emerging rays is taken into account. The extended geometrical-optics approximation (EGOA) permits one to calculate the scattering diagram in all directions from 0 degrees to 180 degrees. The intensities of the scattered field calculated by the EGOA are compared with those calculated by the generalized Lorenz-Mie theory, and good agreement is found. The surface wave effect in Gaussian beam scattering is also qualitatively analyzed by introducing a flux ratio factor. The approach proposed is particularly important to the further extension of the geometrical-optics approximation to the scattering of large spheroidal particles.

Optical design of a high radiative flux solar furnace for Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riveros-Rosas, D.; Perez-Rabago, C.A.; Arancibia-Bulnes, C.A.

2010-05-15

In the present work, the optical design of a new high radiative flux solar furnace is described. Several optical configurations for the concentrator of the system have been considered. Ray tracing simulations were carried out in order to determine the concentrated radiative flux distributions in the focal zone of the system, for comparing the different proposals. The best configuration was chosen in terms of maximum peak concentration, but also in terms of economical and other practical considerations. It consists of an arrangement of 409 first surface spherical facets with hexagonal shape, mounted on a spherical frame. The individual orientation ofmore » the facets is corrected in order to compensate for aberrations. The design considers an intercepted power of 30 kW and a target peak concentration above 10,000 suns. The effect of optical errors was also considered in the simulations. (author)« less

Aerosol Airmass Type Mapping Over the Urban Mexico City Region From Space-based Multi-angle Imaging

NASA Technical Reports Server (NTRS)

Patadia, F.; Kahn, R. A.; Limbacher, J. A.; Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.

2013-01-01

Using Multi-angle Imaging SpectroRadiometer (MISR) and sub-orbital measurements from the 2006 INTEX-B/MILAGRO field campaign, in this study we explore MISR's ability to map different aerosol air mass types over the Mexico City metropolitan area. The aerosol air mass distinctions are based on shape, size and single scattering albedo retrievals from the MISR Research Aerosol Retrieval algorithm. In this region, the research algorithm identifies dust-dominated aerosol mixtures based on non-spherical particle shape, whereas spherical biomass burning and urban pollution particles are distinguished by particle size. Two distinct aerosol air mass types based on retrieved particle microphysical properties, and four spatially distributed aerosol air masses, are identified in the MISR data on 6 March 2006. The aerosol air mass type identification results are supported by coincident, airborne high-spectral-resolution lidar (HSRL) measurements. Aerosol optical depth (AOD) gradients are also consistent between the MISR and sub-orbital measurements, but particles having single-scattering albedo of approx. 0.7 at 558 nm must be included in the retrieval algorithm to produce good absolute AOD comparisons over pollution-dominated aerosol air masses. The MISR standard V22 AOD product, at 17.6 km resolution, captures the observed AOD gradients qualitatively, but retrievals at this coarse spatial scale and with limited spherical absorbing particle options underestimate AOD and do not retrieve particle properties adequately over this complex urban region. However, we demonstrate how AOD and aerosol type mapping can be accomplished with MISR data over complex urban regions, provided the retrieval is performed at sufficiently high spatial resolution, and with a rich enough set of aerosol components and mixtures.

Biomimetic shoulder complex based on 3-PSS/S spherical parallel mechanism

NASA Astrophysics Data System (ADS)

Hou, Yulei; Hu, Xinzhe; Zeng, Daxing; Zhou, Yulin

2015-01-01

The application of the parallel mechanism is still limited in the humanoid robot fields, and the existing parallel humanoid robot joint has not yet been reflected the characteristics of the parallel mechanism completely, also failed to solve the problem, such as small workspace, effectively. From the structural and functional bionic point of view, a three degrees of freedom(DOFs) spherical parallel mechanism for the shoulder complex of the humanoid robot is presented. According to the structure and kinetic characteristics analysis of the human shoulder complex, 3-PSS/S(P for prismatic pair, S for spherical pair) is chosen as the original configuration for the shouder complex. Using genetic algorithm, the optimization of the 3-PSS/S spherical parallel mechanism is performed, and the orientation workspace of the prototype mechanism is enlarged obviously. Combining the practical structure characteristics of the human shouder complex, an offset output mode, which means the output rod of the mechanism turn to any direction at the point a certain distance from the rotation center of the mechanism, is put forward, which provide possibility for the consistent of the workspace of the mechanism and the actual motion space of the human body shoulder joint. The relationship of the attitude angles between different coordinate system is derived, which establishs the foundation for the motion descriptions under different conditions and control development. The 3-PSS/S spherical parallel mechanism is proposed for the shoulder complex, and the consistence of the workspace of the mechanism and the human shoulder complex is realized by the stuctural parameter optimization and the offset output design.

CAD Integration : new optical design possibilities

NASA Astrophysics Data System (ADS)

Haumonte, Jean-Baptiste; Venturino, Jean-Claude

2005-09-01

The development of optical design and analysis tools in a CAD software can help to optimise the design, size and performance of tomorrow's consumer products. While optics was still held back by software limitations, CAD programs were moving forward in leaps and bounds, improving manufacturing technologies and making it possible to design and produce highly innovative and sophisticated products. The problem was that in the past, 'traditional' optical design programs were only able to simulate spherical and aspherical lenses, meaning that the optical designers were limited to designing systems which were a series of imperfect lenses, each one correcting the last. That is why OPTIS has created the first optical design program to be fully integrated into a CAD program. The technology is available from OPTIS in an integrated SOLIDWORKS or CATIA V5 version. Users of this software can reduce the number of lenses needed in a system. Designers will now have access to complex surfaces such as NURBS meaning they will now be able to define free shape progressive lenses and even improve on optical performances using fewer lenses. This revolutionary technology will allow mechanical designers to work on optical systems and to share information with optical designers for the first time. Previously not possible in a CAD program you may now determine all the optical performances of any optical system, providing first order and third order performances, sequential and non-sequential ray-tracing, wavefront surfaces, point spread function, MTF, spot-diagram, using real optical surfaces and guaranteeing the mechanical precision necessary for an optical system.

A Wave-Optics Approach to Paraxial Geometrical Laws Based on Continuity at Boundaries

ERIC Educational Resources Information Center

Linares, J.; Nistal, M. C.

2011-01-01

We present a derivation of the paraxial geometrical laws starting from a wave-optics approach, in particular by using simple continuity conditions of paraxial spherical waves at boundaries (discontinuities) between optical media. Paraxial geometrical imaging and magnification laws, under refraction and reflection at boundaries, are derived for…

Determination of injection molding process windows for optical lenses using response surface methodology.

PubMed

Tsai, Kuo-Ming; Wang, He-Yi

2014-08-20

This study focuses on injection molding process window determination for obtaining optimal imaging optical properties, astigmatism, coma, and spherical aberration using plastic lenses. The Taguchi experimental method was first used to identify the optimized combination of parameters and significant factors affecting the imaging optical properties of the lens. Full factorial experiments were then implemented based on the significant factors to build the response surface models. The injection molding process windows for lenses with optimized optical properties were determined based on the surface models, and confirmation experiments were performed to verify their validity. The results indicated that the significant factors affecting the optical properties of lenses are mold temperature, melt temperature, and cooling time. According to experimental data for the significant factors, the oblique ovals for different optical properties on the injection molding process windows based on melt temperature and cooling time can be obtained using the curve fitting approach. The confirmation experiments revealed that the average errors for astigmatism, coma, and spherical aberration are 3.44%, 5.62%, and 5.69%, respectively. The results indicated that the process windows proposed are highly reliable.

Using radiance predicted by the P3 approximation in a spherical geometry to predict tissue optical properties

NASA Astrophysics Data System (ADS)

Dickey, Dwayne J.; Moore, Ronald B.; Tulip, John

2001-01-01

For photodynamic therapy of solid tumors, such as prostatic carcinoma, to be achieved, an accurate model to predict tissue parameters and light dose must be found. Presently, most analytical light dosimetry models are fluence based and are not clinically viable for tissue characterization. Other methods of predicting optical properties, such as Monet Carlo, are accurate but far too time consuming for clinical application. However, radiance predicted by the P3-Approximation, an anaylitical solution to the transport equation, may be a viable and accurate alternative. The P3-Approximation accurately predicts optical parameters in intralipid/methylene blue based phantoms in a spherical geometry. The optical parameters furnished by the radiance, when introduced into fluence predicted by both P3- Approximation and Grosjean Theory, correlate well with experimental data. The P3-Approximation also predicts the optical properties of prostate tissue, agreeing with documented optical parameters. The P3-Approximation could be the clinical tool necessary to facilitate PDT of solid tumors because of the limited number of invasive measurements required and the speed in which accurate calculations can be performed.

Precision production: enabling deterministic throughput for precision aspheres with MRF

NASA Astrophysics Data System (ADS)

Maloney, Chris; Entezarian, Navid; Dumas, Paul

2017-10-01

Aspherical lenses offer advantages over spherical optics by improving image quality or reducing the number of elements necessary in an optical system. Aspheres are no longer being used exclusively by high-end optical systems but are now replacing spherical optics in many applications. The need for a method of production-manufacturing of precision aspheres has emerged and is part of the reason that the optics industry is shifting away from artisan-based techniques towards more deterministic methods. Not only does Magnetorheological Finishing (MRF) empower deterministic figure correction for the most demanding aspheres but it also enables deterministic and efficient throughput for series production of aspheres. The Q-flex MRF platform is designed to support batch production in a simple and user friendly manner. Thorlabs routinely utilizes the advancements of this platform and has provided results from using MRF to finish a batch of aspheres as a case study. We have developed an analysis notebook to evaluate necessary specifications for implementing quality control metrics. MRF brings confidence to optical manufacturing by ensuring high throughput for batch processing of aspheres.

Effect of anisotropy on intensity fluctuations in oceanic turbulence

NASA Astrophysics Data System (ADS)

Baykal, Yahya

2018-04-01

For an optical spherical wave propagating in an oceanic turbulent medium, the effect of anisotropy on the received intensity fluctuations is investigated. For different anisotropy factors, the variations of the scintillation index vs. the ratio that determines the relative strength of temperature and salinity in the index fluctuations, the rate of dissipation of the mean squared temperature, the rate of dissipation of the turbulent kinetic energy, viscosity, link length and the wavelength are plotted. It is found that, for all the oceanic turbulence and the link parameters of interest, as the medium becomes more anisotropic, the intensity of the optical spherical wave fluctuates less. It is concluded that the performance of an optical wireless communication systems (OWCS) operating in anisotropic oceanic turbulence is better than the performance of OWCS operating in isotropic oceanic turbulence.

Highly curved image sensors: a practical approach for improved optical performance

NASA Astrophysics Data System (ADS)

Guenter, Brian; Joshi, Neel; Stoakley, Richard; Keefe, Andrew; Geary, Kevin; Freeman, Ryan; Hundley, Jake; Patterson, Pamela; Hammon, David; Herrera, Guillermo; Sherman, Elena; Nowak, Andrew; Schubert, Randall; Brewer, Peter; Yang, Louis; Mott, Russell; McKnight, Geoff

2017-06-01

The significant optical and size benefits of using a curved focal surface for imaging systems have been well studied yet never brought to market for lack of a high-quality, mass-producible, curved image sensor. In this work we demonstrate that commercial silicon CMOS image sensors can be thinned and formed into accurate, highly curved optical surfaces with undiminished functionality. Our key development is a pneumatic forming process that avoids rigid mechanical constraints and suppresses wrinkling instabilities. A combination of forming-mold design, pressure membrane elastic properties, and controlled friction forces enables us to gradually contact the die at the corners and smoothly press the sensor into a spherical shape. Allowing the die to slide into the concave target shape enables a threefold increase in the spherical curvature over prior approaches having mechanical constraints that resist deformation, and create a high-stress, stretch-dominated state. Our process creates a bridge between the high precision and low-cost but planar CMOS process, and ideal non-planar component shapes such as spherical imagers for improved optical systems. We demonstrate these curved sensors in prototype cameras with custom lenses, measuring exceptional resolution of 3220 line-widths per picture height at an aperture of f/1.2 and nearly 100% relative illumination across the field. Though we use a 1/2.3" format image sensor in this report, we also show this process is generally compatible with many state of the art imaging sensor formats. By example, we report photogrammetry test data for an APS-C sized silicon die formed to a 30$^\\circ$ subtended spherical angle. These gains in sharpness and relative illumination enable a new generation of ultra-high performance, manufacturable, digital imaging systems for scientific, industrial, and artistic use.

Simultaneous identification of optical constants and PSD of spherical particles by multi-wavelength scattering-transmittance measurement

NASA Astrophysics Data System (ADS)

Zhang, Jun-You; Qi, Hong; Ren, Ya-Tao; Ruan, Li-Ming

2018-04-01

An accurate and stable identification technique is developed to retrieve the optical constants and particle size distributions (PSDs) of particle system simultaneously from the multi-wavelength scattering-transmittance signals by using the improved quantum particle swarm optimization algorithm. The Mie theory are selected to calculate the directional laser intensity scattered by particles and the spectral collimated transmittance. The sensitivity and objective function distribution analysis were conducted to evaluate the mathematical properties (i.e. ill-posedness and multimodality) of the inverse problems under three different optical signals combinations (i.e. the single-wavelength multi-angle light scattering signal, the single-wavelength multi-angle light scattering and spectral transmittance signal, and the multi-angle light scattering and spectral transmittance signal). It was found the best global convergence performance can be obtained by using the multi-wavelength scattering-transmittance signals. Meanwhile, the present technique have been tested under different Gaussian measurement noise to prove its feasibility in a large solution space. All the results show that the inverse technique by using multi-wavelength scattering-transmittance signals is effective and suitable for retrieving the optical complex refractive indices and PSD of particle system simultaneously.

Spectral-optical-electrical-thermal properties of deposited thin films of nano-sized calcium(II)-8-hydroxy-5,7-dinitroquinolate complex.

PubMed

Farag, A A M; Haggag, Sawsan M S; Mahmoud, Mohamed E

2011-11-01

Spectral-optical-electrical-thermal properties of deposited thin films of nano-sized calcium(II)-8-hydroxy-5,7-dinitroquinolate complex, Ca[((NO(2))(2)-8HQ)(2)], were explored, studied and evaluated in this work. Thin films of Ca[((NO(2))(2)-8HQ)(2)] were assembled by using a direct, simple and efficient layer-by-layer (LBL) chemical deposition technique. The optical properties of thin films were investigated by using spectrophotometric measurements of transmittance and reflectance at normal incidence in the wavelength range 200-2500 nm. The refractive index, n, and the absorption index, k, of Ca[((NO(2))(2)-8HQ)(2)] films were determined from the measured transmittance and reflectance. The real and imaginary dielectric constants were also determined. The analysis of the spectral behavior of the absorption coefficient in the intrinsic absorption region reveals a direct allowed transition with band gaps of 1.1 eV and 2.4 eV for the optical and transport energy gaps, respectively. The current-voltage characteristics of Ca[((NO(2))(2)-8HQ)(2)] showed a trap-charge limited conduction in determining the current at the intermediate and high bias regimes. Graphical representation of the current-voltage characteristics yields three distinct linear parts indicating the existence of three conduction mechanisms. Structural characterization and identification were confirmed by using Fourier transform infrared spectroscopy (FT-IR). Scanning electron microscopy (SEM) was also used to image the surface morphology of the deposited nano-sized metal complex and such study revealed a high homogeneity in surface spherical particle distribution with average particles size in the range 20-40 nm. Thermal gravimetric analysis (TGA) was also studied for [(NO(2))(2)-8HQ] and Ca[((NO(2))(2)-8HQ)(2)] to evaluate and confirm the thermal stability characteristics incorporated into the synthesized nano-sized Ca[((NO(2))(2)-8HQ)(2)] complex. Copyright © 2011 Elsevier B.V. All rights reserved.

Determining spherical lens correction for astronaut training underwater.

PubMed

Porter, Jason; Gibson, C Robert; Strauss, Samuel

2011-09-01

To develop a model that will accurately predict the distance spherical lens correction needed to be worn by National Aeronautics and Space Administration astronauts while training underwater. The replica space suit's helmet contains curved visors that induce refractive power when submersed in water. Anterior surface powers and thicknesses were measured for the helmet's protective and inside visors. The impact of each visor on the helmet's refractive power in water was analyzed using thick lens calculations and Zemax optical design software. Using geometrical optics approximations, a model was developed to determine the optimal distance spherical power needed to be worn underwater based on the helmet's total induced spherical power underwater and the astronaut's manifest spectacle plane correction in air. The validity of the model was tested using data from both eyes of 10 astronauts who trained underwater. The helmet's visors induced a total power of -2.737 D when placed underwater. The required underwater spherical correction (FW) was linearly related to the spectacle plane spherical correction in air (FAir): FW = FAir + 2.356 D. The mean magnitude of the difference between the actual correction worn underwater and the calculated underwater correction was 0.20 ± 0.11 D. The actual and calculated values were highly correlated (r = 0.971) with 70% of eyes having a difference in magnitude of <0.25 D between values. We devised a model to calculate the spherical spectacle lens correction needed to be worn underwater by National Aeronautics and Space Administration astronauts. The model accurately predicts the actual values worn underwater and can be applied (more generally) to determine a suitable spectacle lens correction to be worn behind other types of masks when submerged underwater.

Determining spherical lens correction for astronaut training underwater

PubMed Central

Porter, Jason; Gibson, C. Robert; Strauss, Samuel

2013-01-01

Purpose To develop a model that will accurately predict the distance spherical lens correction needed to be worn by National Aeronautics and Space Administration (NASA) astronauts while training underwater. The replica space suit’s helmet contains curved visors that induce refractive power when submersed in water. Methods Anterior surface powers and thicknesses were measured for the helmet’s protective and inside visors. The impact of each visor on the helmet’s refractive power in water was analyzed using thick lens calculations and Zemax optical design software. Using geometrical optics approximations, a model was developed to determine the optimal distance spherical power needed to be worn underwater based on the helmet’s total induced spherical power underwater and the astronaut’s manifest spectacle plane correction in air. The validity of the model was tested using data from both eyes of 10 astronauts who trained underwater. Results The helmet visors induced a total power of −2.737 D when placed underwater. The required underwater spherical correction (FW) was linearly related to the spectacle plane spherical correction in air (FAir): FW = FAir + 2.356 D. The mean magnitude of the difference between the actual correction worn underwater and the calculated underwater correction was 0.20 ± 0.11 D. The actual and calculated values were highly correlated (R = 0.971) with 70% of eyes having a difference in magnitude of < 0.25 D between values. Conclusions We devised a model to calculate the spherical spectacle lens correction needed to be worn underwater by National Aeronautics and Space Administration astronauts. The model accurately predicts the actual values worn underwater and can be applied (more generally) to determine a suitable spectacle lens correction to be worn behind other types of masks when submerged underwater. PMID:21623249

Aberration corrected STEM by means of diffraction gratings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Linck, Martin; Ercius, Peter A.; Pierce, Jordan S.

In the past 15 years, the advent of aberration correction technology in electron microscopy has enabled materials analysis on the atomic scale. This is made possible by precise arrangements of multipole electrodes and magnetic solenoids to compensate the aberrations inherent to any focusing element of an electron microscope. In this paper, we describe an alternative method to correct for the spherical aberration of the objective lens in scanning transmission electron microscopy (STEM) using a passive, nanofabricated diffractive optical element. This holographic device is installed in the probe forming aperture of a conventional electron microscope and can be designed to removemore » arbitrarily complex aberrations from the electron's wave front. In this work, we show a proof-of-principle experiment that demonstrates successful correction of the spherical aberration in STEM by means of such a grating corrector (GCOR). Our GCOR enables us to record aberration-corrected high-resolution high-angle annular dark field (HAADF-) STEM images, although yet without advancement in probe current and resolution. Finally, improvements in this technology could provide an economical solution for aberration-corrected high-resolution STEM in certain use scenarios.« less

Aberration corrected STEM by means of diffraction gratings

DOE PAGES

Linck, Martin; Ercius, Peter A.; Pierce, Jordan S.; ...

2017-06-12

In the past 15 years, the advent of aberration correction technology in electron microscopy has enabled materials analysis on the atomic scale. This is made possible by precise arrangements of multipole electrodes and magnetic solenoids to compensate the aberrations inherent to any focusing element of an electron microscope. In this paper, we describe an alternative method to correct for the spherical aberration of the objective lens in scanning transmission electron microscopy (STEM) using a passive, nanofabricated diffractive optical element. This holographic device is installed in the probe forming aperture of a conventional electron microscope and can be designed to removemore » arbitrarily complex aberrations from the electron's wave front. In this work, we show a proof-of-principle experiment that demonstrates successful correction of the spherical aberration in STEM by means of such a grating corrector (GCOR). Our GCOR enables us to record aberration-corrected high-resolution high-angle annular dark field (HAADF-) STEM images, although yet without advancement in probe current and resolution. Finally, improvements in this technology could provide an economical solution for aberration-corrected high-resolution STEM in certain use scenarios.« less

Electromagnetic cloaking in higher order spherical cloaks

NASA Astrophysics Data System (ADS)

Sidhwa, H. H.; Aiyar, R. P. R. C.; Kulkarni, S. V.

2017-06-01

The inception of transformation optics has led to the realisation of the invisibility devices for various applications, one of which is spherical cloaking. In this paper, a formulation for a higher-order spherical cloak has been proposed to reduce its physical thickness significantly by introducing a nonlinear relation between the original and transformed coordinate systems and it has been verified using the ray tracing approach. Analysis has been carried out to observe the anomalies in the variation of refractive index for higher order cloaks indicating the presence of poles in the relevant equations. Furthermore, a higher-order spherical cloak with predefined values of the material characteristics on its inner and outer surfaces has been designed for practical application.

Measurement of spatio-temporal field distribution of THz pulses in electro-optic crystal by interferometry method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chizhov, P A; Ushakov, A A; Bukin, V V

2015-05-31

We propose a scheme for measuring the spatial distribution of the THz pulse electric field strength in an electro-optic crystal using optical interferometry. The resulting images of the field distribution from a test source with a spherical wave front are presented. (extreme light fields and their applications)

Interferometric analysis of polishing surface with a petal tool

NASA Astrophysics Data System (ADS)

Salas-Sánchez, Alfonso; Leal-Cabrera, Irce; Percino Zacarias, Elizabeth; Granados-Agustín, Fermín S.

2011-09-01

In this work, we describe a phase shift interferometric monitoring of polishing processes produced by a petal tool over a spherical surface to obtain a parabolic surface. In the process, we used a commercial polishing machine; the purpose of this work is to have control of polishing time. To achieve this analysis, we used a Fizeau interferometer of ZYGO Company for optical shop testing, and the Durango software from Diffraction International Company. For data acquisition, simulation and evaluation of optical surfaces, we start polishing process with a spherical surface with 15.46 cm of diameter; a 59.9 cm of radius curvature and, with f/# 1.9.

Assessment of the performance of a compact concentric spectrometer system for Atmospheric Differential Optical Absorption Spectroscopy

NASA Astrophysics Data System (ADS)

Whyte, C.; Leigh, R. J.; Lobb, D.; Williams, T.; Remedios, J. J.; Cutter, M.; Monks, P. S.

2009-12-01

A breadboard demonstrator of a novel UV/VIS grating spectrometer has been developed based upon a concentric arrangement of a spherical meniscus lens, concave spherical mirror and curved diffraction grating suitable for a range of atmospheric remote sensing applications from the ground or space. The spectrometer is compact and provides high optical efficiency and performance benefits over traditional instruments. The concentric design is capable of handling high relative apertures, owing to spherical aberration and comma being near zero at all surfaces. The design also provides correction for transverse chromatic aberration and distortion, in addition to correcting for the distortion called "smile", the curvature of the slit image formed at each wavelength. These properties render this design capable of superior spectral and spatial performance with size and weight budgets significantly lower than standard configurations. This form of spectrometer design offers the potential for exceptionally compact instrument for differential optical absorption spectroscopy (DOAS) applications from LEO, GEO, HAP or ground-based platforms. The breadboard demonstrator has been shown to offer high throughput and a stable Gaussian line shape with a spectral range from 300 to 450 nm at 0.5 nm resolution, suitable for a number of typical DOAS applications.

Comparison of Color Fundus Photography, Infrared Fundus Photography, and Optical Coherence Tomography in Detecting Retinal Hamartoma in Patients with Tuberous Sclerosis Complex.

PubMed

Bai, Da-Yong; Wang, Xu; Zhao, Jun-Yang; Li, Li; Gao, Jun; Wang, Ning-Li

2016-05-20

A sensitive method is required to detect retinal hamartomas in patients with tuberous sclerosis complex (TSC). The aim of the present study was to compare the color fundus photography, infrared imaging (IFG), and optical coherence tomography (OCT) in the detection rate of retinal hamartoma in patients with TSC. This study included 11 patients (22 eyes) with TSC, who underwent color fundus photography, IFG, and spectral-domain OCT to detect retinal hamartomas. TSC1 and TSC2RESULTS: The mean age of the 11 patients was 8.0 ± 2.1 years. The mean spherical equivalent was -0.55 ± 1.42 D by autorefraction with cycloplegia. In 11 patients (22 eyes), OCT, infrared fundus photography, and color fundus photography revealed 26, 18, and 9 hamartomas, respectively. The predominant hamartoma was type I (55.6%). All the hamartomas that detected by color fundus photography or IFG can be detected by OCT. Among the methods of color fundus photography, IFG, and OCT, the OCT has higher detection rate for retinal hamartoma in TSC patients; therefore, OCT might be promising for the clinical diagnosis of TSC.

Photonic Microresonators from Charge Transfer in Polymer Particles: Toward Enhanced and Tunable Two-Photon Emission.

PubMed

Vattikunta, Radhika; Venkatakrishnarao, Dasari; Sahoo, Chakradhar; Naraharisetty, Sri Ram Gopal; Narayana Rao, Desai; Müllen, Klaus; Chandrasekar, Rajadurai

2018-05-16

Novel photonic microresonators with enhanced nonlinear optical (NLO) intensity are fabricated from polymer particles. As an additional advantage, they offer band gap tunability from the visible to near-infrared regions. A special protocol including (i) copolymerization of 4-(1-pyrenyl)-styrene, styrene, and 1,4-divinylbenzene, (ii) extraction of a dispersible and partly dissolvable, lightly cross-linked polymer network (PN), and (iii) treatment of the blue-emitting PN with electron acceptor (A) molecules such as 1,2,4,5-tetracyanobenzene (TCNB) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) furnishes orange- and red-emitting D-A charge-transfer (CT) complexes with the pendant pyrene units. These complexes, here named PN-TCNB and PN-TCNQ, respectively, precipitate as microparticles upon the addition of water and subsequent ultrasonication. Upon electronic excitation, these spherical microparticles act as whispering-gallery-mode resonators by displaying optical resonances in the photoluminescence (PL) spectra because of light confinement. Further, the trapped incident light increases the light-matter interaction and thereby enhances the PL intensity, including the two-photon luminescence. The described protocol for polymer-based CT microresonators with tunable NLO emissions holds promise for a myriad of photonic applications.

New spherical optical cavities with non-degenerated whispering gallery modes

NASA Astrophysics Data System (ADS)

Kumagai, Tsutaru; Palma, Giuseppe; Prudenzano, Francesco; Kishi, Tetsuo; Yano, Tetsuji

2017-02-01

New spherical resonators with internal defects are introduced to show anomalous whispering gallery modes (WGMs). The defect induces a symmetry breaking spherical cavity and splits the WGMs. A couple of defects, a hollow sphere (bubble), and a hollow ring, have been studied. The hollow sphere was fabricated and the splitting of WGM was observed. In this paper, this "non-degenerated WGMs (non-DWGMs) resonance" in a microsphere with hollow defect structure is reviewed based on our research. The resonance of WGMs in a sphere is identified by three integer parameters: the angular mode number, l, azimuthal mode number m, and radial mode number, n. The placement of the defect such as a hollow ring or single bubble is shown to break symmetry and resolve the degeneracy concerning m. This induces a variety of resonant wavelengths of the spherical cavity. A couple of simulations using the eigenmode and transient analyses propose how the placed defects affect the WGM resonance in the spherical cavity. For the sphere with a single bubble defect, the experimentally observed resonances in Nd-doped tellurite glass microsphere with a single bubble are clarified to be due to the splitting of resonance modes, i.e., the existence of "non-DWGMs" in the sphere. The defect bubble plays a role of opening the optically wide gate to introduce excitation light for Nd3+ pumping using non-DWGMs in the sphere efficiently.

Schmidt Telescope

NASA Astrophysics Data System (ADS)

Murdin, P.

2000-11-01

A type of telescope, invented by the Estonian optician Bernhard Schmidt (1879-1935), that is used to photograph large areas of the sky. Because, in its original design, it was useable only for photography, the instrument is also known as the Schmidt camera. The Schmidt uses a concave spherical mirror as its light collector and corrects for the optical defect, known as spherical aberration, that i...

Wavefront-Guided Scleral Lens Prosthetic Device for Keratoconus

PubMed Central

Sabesan, Ramkumar; Johns, Lynette; Tomashevskaya, Olga; Jacobs, Deborah S.; Rosenthal, Perry; Yoon, Geunyoung

2016-01-01

Purpose To investigate the feasibility of correcting ocular higher order aberrations (HOA) in keratoconus (KC) using wavefront-guided optics in a scleral lens prosthetic device (SLPD). Methods Six advanced keratoconus patients (11 eyes) were fitted with a SLPD with conventional spherical optics. A custom-made Shack-Hartmann wavefront sensor was used to measure aberrations through a dilated pupil wearing the SLPD. The position of SLPD, i.e. horizontal and vertical decentration relative to the pupil and rotation were measured and incorporated into the design of the wavefront-guided optics for the customized SLPD. A submicron-precision lathe created the designed irregular profile on the front surface of the device. The residual aberrations of the same eyes wearing the SLPD with wavefront-guided optics were subsequently measured. Visual performance with natural mesopic pupil was compared between SLPDs having conventional spherical and wavefront-guided optics by measuring best-corrected high-contrast visual acuity and contrast sensitivity. Results Root-mean-square of HOA(RMS) in the 11 eyes wearing conventional SLPD with spherical optics was 1.17±0.57μm for a 6 mm pupil. HOA were effectively corrected by the customized SLPD with wavefront-guided optics and RMS was reduced 3.1 times on average to 0.37±0.19μm for the same pupil. This correction resulted in significant improvement of 1.9 lines in mean visual acuity (p<0.05). Contrast sensitivity was also significantly improved by a factor of 2.4, 1.8 and 1.4 on average for 4, 8 and 12 cycles/degree, respectively (p<0.05 for all frequencies). Although the residual aberration was comparable to that of normal eyes, the average visual acuity in logMAR with the customized SLPD was 0.21, substantially worse than normal acuity. Conclusions The customized SLPD with wavefront-guided optics corrected the HOA of advanced KC patients to normal levels and improved their vision significantly. PMID:23478630

Changes in Monkey Crystalline Lens Spherical Aberration During Simulated Accommodation in a Lens Stretcher

PubMed Central

Maceo Heilman, Bianca; Manns, Fabrice; de Castro, Alberto; Durkee, Heather; Arrieta, Esdras; Marcos, Susana; Parel, Jean-Marie

2015-01-01

Purpose. The purpose of this study was to quantify accommodation-induced changes in the spherical aberration of cynomolgus monkey lenses. Methods. Twenty-four lenses from 20 cynomolgus monkeys (Macaca fascicularis; 4.4–16.0 years of age; postmortem time 13.5 ± 13.0 hours) were mounted in a lens stretcher. Lens spherical aberration was measured in the unstretched (accommodated) and stretched (relaxed) states with a laser ray tracing system that delivered 51 equally spaced parallel rays along 1 meridian of the lens over the central 6-mm optical zone. A camera mounted below the lens was used to measure the ray height at multiple positions along the optical axis. For each entrance ray, the change in ray height with axial position was fitted with a third-order polynomial. The effective paraxial focal length and Zernike spherical aberration coefficients corresponding to a 6-mm pupil diameter were extracted from the fitted values. Results. The unstretched lens power decreased with age from 59.3 ± 4.0 diopters (D) for young lenses to 45.7 ± 3.1 D for older lenses. The unstretched lens shifted toward less negative spherical aberration with age, from −6.3 ± 0.7 μm for young lenses to −5.0 ± 0.5 μm for older lenses. The power and spherical aberration of lenses in the stretched state were independent of age, with values of 33.5 ± 3.4 D and −2.6 ± 0.5 μm, respectively. Conclusions. Spherical aberration is negative in cynomolgus monkey lenses and becomes more negative with accommodation. These results are in good agreement with the predicted values using computational ray tracing in a lens model with a reconstructed gradient refractive index. The spherical aberration of the unstretched lens becomes less negative with age. PMID:25670492

Changes in monkey crystalline lens spherical aberration during simulated accommodation in a lens stretcher.

PubMed

Maceo Heilman, Bianca; Manns, Fabrice; de Castro, Alberto; Durkee, Heather; Arrieta, Esdras; Marcos, Susana; Parel, Jean-Marie

2015-02-10

The purpose of this study was to quantify accommodation-induced changes in the spherical aberration of cynomolgus monkey lenses. Twenty-four lenses from 20 cynomolgus monkeys (Macaca fascicularis; 4.4-16.0 years of age; postmortem time 13.5 ± 13.0 hours) were mounted in a lens stretcher. Lens spherical aberration was measured in the unstretched (accommodated) and stretched (relaxed) states with a laser ray tracing system that delivered 51 equally spaced parallel rays along 1 meridian of the lens over the central 6-mm optical zone. A camera mounted below the lens was used to measure the ray height at multiple positions along the optical axis. For each entrance ray, the change in ray height with axial position was fitted with a third-order polynomial. The effective paraxial focal length and Zernike spherical aberration coefficients corresponding to a 6-mm pupil diameter were extracted from the fitted values. The unstretched lens power decreased with age from 59.3 ± 4.0 diopters (D) for young lenses to 45.7 ± 3.1 D for older lenses. The unstretched lens shifted toward less negative spherical aberration with age, from -6.3 ± 0.7 μm for young lenses to -5.0 ± 0.5 μm for older lenses. The power and spherical aberration of lenses in the stretched state were independent of age, with values of 33.5 ± 3.4 D and -2.6 ± 0.5 μm, respectively. Spherical aberration is negative in cynomolgus monkey lenses and becomes more negative with accommodation. These results are in good agreement with the predicted values using computational ray tracing in a lens model with a reconstructed gradient refractive index. The spherical aberration of the unstretched lens becomes less negative with age. Copyright 2015 The Association for Research in Vision and Ophthalmology, Inc.

Dark field differential dynamic microscopy enables accurate characterization of the roto-translational dynamics of bacteria and colloidal clusters

NASA Astrophysics Data System (ADS)

Cerbino, Roberto; Piotti, Davide; Buscaglia, Marco; Giavazzi, Fabio

2018-01-01

Micro- and nanoscale objects with anisotropic shape are key components of a variety of biological systems and inert complex materials, and represent fundamental building blocks of novel self-assembly strategies. The time scale of their thermal motion is set by their translational and rotational diffusion coefficients, whose measurement may become difficult for relatively large particles with small optical contrast. Here we show that dark field differential dynamic microscopy is the ideal tool for probing the roto-translational Brownian motion of anisotropic shaped particles. We demonstrate our approach by successful application to aqueous dispersions of non-motile bacteria and of colloidal aggregates of spherical particles.

Precision lens molding of asphero diffractive surfaces in chalcogenide materials

NASA Astrophysics Data System (ADS)

Nelson, J.; Scordato, M.; Schwertz, K.; Bagwell, J.

2015-10-01

Finished lens molding, and the similar process of precision lens molding, have long been practiced for high volume, accurate replication of optical surfaces on oxide glass. The physics surrounding these processes are well understood, and the processes are capable of producing high quality optics with great fidelity. However, several limitations exist due to properties inherent with oxide glasses. Tooling materials that can withstand the severe environmental conditions of oxide glass molding cannot easily be machined to produce complex geometries such as diffractive surfaces, lens arrays, and off axis features. Current machining technologies coupled with a limited selection of tool materials greatly limits the type of structures that can be molded into the finished optic. Tooling for chalcogenide glasses are not bound by these restrictions since the molding temperatures required are much lower than for oxide glasses. Innovations in tooling materials and manufacturing techniques have enabled the production of complex geometries to optical quality specifications and have demonstrated the viability of creating tools for molding diffractive surfaces, off axis features, datums, and arrays. Applications for optics having these features are found in automotive, defense, security, medical, and industrial domains. This paper will discuss results achieved in the study of various molding techniques for the formation of positive diffractive features on a concave spherical surface molded from As2Se3 chalcogenide glass. Examples and results of molding with tools having CTE match with the glass and non CTE match will be reviewed. The formation of stress within the glass during molding will be discussed, and methods of stress management will also be demonstrated and discussed. Results of process development methods and production of good diffractive surfaces will be shown.

Electron-induced scattering dynamics of Boron, Aluminium and Gallium trihalides in the intermediate energy domain

NASA Astrophysics Data System (ADS)

Verma, Pankaj; Alam, Mohammad Jane; Ahmad, Shabbir; Antony, Bobby

2018-05-01

This article is focused on the calculation of electron-induced ionisation and total scattering cross sections by Boron, Aluminium and Gallium trihalide molecules in the intermediate energy domain. The computational formalism, spherical complex optical potential has been employed for the study of these two scattering cross sections. The ionisation cross section has been derived from the inelastic cross section using a semi-empirical method called complex scattering potential-ionisation contribution (CSP-ic) method. We have also calculated the ionisation cross section using the BEB theory with Hartree-Fock and density functional theory (DFT- ωB97XD) orbitals so that a comparison can be made with the cross sections predicted by CSP-ic method. For this theoretical study, we have also calculated polarisability and bond length of some targets which were not found in literature using DFT/B3LYP in Gaussian 09 software.

Influence of shape and gradient refractive index in the accommodative changes of spherical aberration in nonhuman primate crystalline lenses.

PubMed

de Castro, Alberto; Birkenfeld, Judith; Maceo, Bianca; Manns, Fabrice; Arrieta, Esdras; Parel, Jean-Marie; Marcos, Susana

2013-09-11

To estimate changes in surface shape and gradient refractive index (GRIN) profile in primate lenses as a function of accommodation. To quantify the contribution of surface shape and GRIN to spherical aberration changes with accommodation. Crystalline lenses from 15 cynomolgus monkeys were studied in vitro under different levels of accommodation produced by a stretching system. Lens shape was obtained from optical coherence tomography (OCT) cross-sectional images. The GRIN was reconstructed with a search algorithm using the optical path measured from OCT images and the measured back focal length. The spherical aberration of the lens was estimated as a function of accommodation using the reconstructed GRIN and a homogeneous refractive index. The lens anterior and posterior radii of curvature decreased with increasing lens power. Both surfaces exhibited negative asphericities in the unaccommodated state. The anterior surface conic constant shifted toward less negative values with accommodation, while the value of the posterior remained constant. GRIN parameters remained constant with accommodation. The lens spherical aberration with GRIN distribution was negative and higher in magnitude than that with a homogeneous equivalent refractive index (by 29% and 53% in the unaccommodated and fully accommodated states, respectively). Spherical aberration with the equivalent refractive index shifted with accommodation toward negative values (-0.070 μm/diopter [D]), but the reconstructed GRIN shifted it farther (-0.124 μm/D). When compared with the lens with the homogeneous equivalent refractive index, the reconstructed GRIN lens has more negative spherical aberration and a larger shift toward more negative values with accommodation.

Multi-optical-axis measurement of freeform progressive addition lenses using a Hartmann-Shack wavefront sensor

NASA Astrophysics Data System (ADS)

Xiang, Huazhong; Guo, Hang; Fu, Dongxiang; Zheng, Gang; Zhuang, Songlin; Chen, JiaBi; Wang, Cheng; Wu, Jie

2018-05-01

To precisely measure the whole-surface characterization of freeform progressive addition lenses (PALs), considering the multi-optical-axis conditions is becoming particularly important. Spherical power and astigmatism (cylinder) measurements for freeform PALs, using a Hartmann-Shack wavefront sensor (HSWFS) are proposed herein. Conversion formulas for the optical performance results were provided as HSWFS Zernike polynomial expansions. For each selected zone, the studied PALs were placed and tilted to simulate the multi-optical-axis conditions. The results of two tested PALs were analyzed using MATLAB programs and represented as contour plots of the spherical equivalent and cylinder of the whole-surface. The proposed experimental setup can provide a high accuracy as well as a possibility of choosing 12 lines and positions of 193 measurement zones on the entire surface. This approach to PAL analysis is potentially an efficient and useful method to objectively evaluate the optical performances, in which the full lens surface is defined and expressed as the contour plots of power in different regions (i.e., the distance region, progressive region, and near region) of the lens for regions of interest.

Optical levitation of a non-spherical particle in a loosely focused Gaussian beam.

PubMed

Chang, Cheong Bong; Huang, Wei-Xi; Lee, Kyung Heon; Sung, Hyung Jin

2012-10-08

The optical force on a non-spherical particle subjected to a loosely focused laser beam was calculated using the dynamic ray tracing method. Ellipsoidal particles with different aspect ratios, inclination angles, and positions were modeled, and the effects of these parameters on the optical force were examined. The vertical component of the optical force parallel to the laser beam axis decreased as the aspect ratio decreased, whereas the ellipsoid with a small aspect ratio and a large inclination angle experienced a large vertical optical force. The ellipsoids were pulled toward or repelled away from the laser beam axis, depending on the inclination angle, and they experienced a torque near the focal point. The behavior of the ellipsoids in a viscous fluid was examined by analyzing a dynamic simulation based on the penalty immersed boundary method. As the ellipsoids levitated along the direction of the laser beam propagation, they moved horizontally with rotation. Except for the ellipsoid with a small aspect ratio and a zero inclination angle near the focal point, the ellipsoids rotated until the major axis aligned with the laser beam axis.

Ultra-Light Precision Membrane Optics

NASA Technical Reports Server (NTRS)

Moore, Jim; Gunter, Kent; Patrick, Brian; Marty, Dave; Bates, Kevin; Gatlin, Romona; Clayton, Bill; Rood, Bob; Brantley, Whitt (Technical Monitor)

2001-01-01

SRS Technologies and NASA Marshall Space Flight Center have conducted a research effort to explore the possibility of developing ultra-lightweight membrane optics for future imaging applications. High precision optical flats and spherical mirrors were produced under this research effort. The thin film mirrors were manufactured using surface replication casting of CPI(Trademark), a polyimide material developed specifically for UV hardness and thermal stability. In the course of this program, numerous polyimide films were cast with surface finishes better than 1.5 nanometers rms and thickness variation of less than 63 nanometers. Precision membrane optical flats were manufactured demonstrating better than 1/13 wave figure error when measured at 633 nanometers. The aerial density of these films is 0.037 kilograms per square meter. Several 0.5-meter spherical mirrors were also manufactured. These mirrors had excellent surface finish (1.5 nanometers rms) and figure error on the order of tens of microns. This places their figure error within the demonstrated correctability of advanced wavefront correction technologies such as real time holography.

Optical properties of benthic photosynthetic communities: fiber-optic studies of cyanobacterial mats

NASA Technical Reports Server (NTRS)

Jorgensen, B. B.; Des Marais, D. J.

1988-01-01

A fiber-optic microphobe was used to analyze the spectral light gradients in benthic cyanobacterial mats with 50-micrometer depth resolution and 10-nm spectral resolution. Microcoleus chthononplastes mats were collected from hypersaline, coastal ponds at Guerrero Negro, Baja California. Gradients of spectral radiance, L, were measured at different angles through the mats and the spherically integrated scalar irradiance, Eo, was calculated. Maximal spectral light attenuation was found at the absorption peaks for the dominant photosynthetic pigments: chlorophyll a at 430 and 670 nm, carotenoids at 450-500 nm, phycocyanin at 620 nm, and bacteriochlorophyll a at 800-900 nm. Scattered light had a marked spectral effect on the scalar irradiance which near the mat surface reached up to 190% of the incident irradiance. The spherically integrated irradiance thus differed strongly from the incident irradiance both in total intensity and in spectral composition. These basic optical properties are important for the understanding of photosynthesis and light harvesting in benthic and epiphytic communities.

Tomographic active optical trapping of arbitrarily shaped objects by exploiting 3D refractive index maps

NASA Astrophysics Data System (ADS)

Kim, Kyoohyun; Park, Yongkeun

2017-05-01

Optical trapping can manipulate the three-dimensional (3D) motion of spherical particles based on the simple prediction of optical forces and the responding motion of samples. However, controlling the 3D behaviour of non-spherical particles with arbitrary orientations is extremely challenging, due to experimental difficulties and extensive computations. Here, we achieve the real-time optical control of arbitrarily shaped particles by combining the wavefront shaping of a trapping beam and measurements of the 3D refractive index distribution of samples. Engineering the 3D light field distribution of a trapping beam based on the measured 3D refractive index map of samples generates a light mould, which can manipulate colloidal and biological samples with arbitrary orientations and/or shapes. The present method provides stable control of the orientation and assembly of arbitrarily shaped particles without knowing a priori information about the sample geometry. The proposed method can be directly applied in biophotonics and soft matter physics.

Automatic assembly of micro-optical components

NASA Astrophysics Data System (ADS)

Gengenbach, Ulrich K.

1996-12-01

Automatic assembly becomes an important issue as hybrid micro systems enter industrial fabrication. Moving from a laboratory scale production with manual assembly and bonding processes to automatic assembly requires a thorough re- evaluation of the design, the characteristics of the individual components and of the processes involved. Parts supply for automatic operation, sensitive and intelligent grippers adapted to size, surface and material properties of the microcomponents gain importance when the superior sensory and handling skills of a human are to be replaced by a machine. This holds in particular for the automatic assembly of micro-optical components. The paper outlines these issues exemplified at the automatic assembly of a micro-optical duplexer consisting of a micro-optical bench fabricated by the LIGA technique, two spherical lenses, a wavelength filter and an optical fiber. Spherical lenses, wavelength filter and optical fiber are supplied by third party vendors, which raises the question of parts supply for automatic assembly. The bonding processes for these components include press fit and adhesive bonding. The prototype assembly system with all relevant components e.g. handling system, parts supply, grippers and control is described. Results of first automatic assembly tests are presented.

Comparison of elliptical and spherical mirrors for the grasshopper monochromators at SSRL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Waldhauer, A. P.

1989-07-01

A comparison of the performance of a spherical and elliptical mirror in the grasshopper monochromator is presented. The problem was studied by ray tracing and then tested using visible (/lambda/=633 nm) laser light. Calculations using ideal optics yield an improvement in flux by a factor of up to 2.7, while tests with visible light show an increase by a factor of 5 because the old spherical mirror is compared to a new, perfect elliptical one. The FWHM of the measured focus is 90 /mu/m with a spherical mirror, and 25 /mu/m with an elliptical one. Elliptical mirrors have been acquiredmore » and are now being installed in the two grasshoppers at SSRL.« less

Non-astigmatic imaging with matched pairs of spherically bent reflectors

DOEpatents

Bitter, Manfred Ludwig [Princeton, NJ; Hill, Kenneth Wayne [Plainsboro, NJ; Scott, Steven Douglas [Wellesley, MA; Feder, Russell [Newton, PA; Ko, Jinseok [Cambridge, MA; Rice, John E [N. Billerica, MA; Ince-Cushman, Alexander Charles [New York, NY; Jones, Frank [Manalapan, NJ

2012-07-10

Arrangements for the point-to-point imaging of a broad spectrum of electromagnetic radiation and ultrasound at large angles of incidence employ matched pairs of spherically bent reflectors to eliminate astigmatic imaging errors. Matched pairs of spherically bent crystals or spherically bent multi-layers are used for X-rays and EUV radiation; and matched pairs of spherically bent mirrors that are appropriate for the type of radiation are used with microwaves, infrared and visible light, or ultrasound. The arrangements encompass the two cases, where the Bragg angle--the complement to the angle of incidence in optics--is between 45.degree. and 90.degree. on both crystals/mirrors or between 0.degree. and 45.degree. on the first crystal/mirror and between 45.degree. and 90.degree. on the second crystal/mirror, where the angles of convergence and divergence are equal. For x-rays and EUV radiation, also the Bragg condition is satisfied on both spherically bent crystals/multi-layers.

Optical Design of Adaptive Optics Confocal Scanning Laser Ophthalmoscope with Two Deformable Mirrors.

PubMed

Yang, Jinsheng; Wang, Yuanyuan; Rao, Xuejun; Wei, Ling; Li, Xiqi; He, Yi

2017-01-01

We describe the optical design of a confocal scanning laser ophthalmoscope with two deformable mirrors. Spherical mirrors are used for pupil relay. Defocus aberration of the human eye is corrected by a Badal focusing structure and astigmatism aberration is corrected by a deformable mirror. The main optical system achieves a diffraction-limited performance through the entire scanning field (6 mm pupil, 3 degrees on pupil plane). The performance of the optical system, with correction of defocus and astigmatism, is also evaluated.

Off-axis mirror fabrication from spherical surfaces under mechanical stress

NASA Astrophysics Data System (ADS)

Izazaga-Pérez, R.; Aguirre-Aguirre, D.; Percino-Zacarías, M. E.; Granados-Agustín, Fermin-Salomon

2013-09-01

The preliminary results in the fabrication of off-axis optical surfaces are presented. The propose using the conventional polishing method and with the surface under mechanical stress at its edges. It starts fabricating a spherical surface using ZERODUR® optical glass with the conventional polishing method, the surface is deformed by applying tension and/or compression at the surface edges using a specially designed mechanical mount. To know the necessary deformation, the interferogram of the deformed surface is analyzed in real time with a ZYGO® Mark II Fizeau type interferometer, the mechanical stress is applied until obtain the inverse interferogram associated to the off-axis surface that we need to fabricate. Polishing process is carried out again until obtain a spherical surface, then mechanical stress in the edges are removed and compares the actual interferogram with the theoretical associated to the off-axis surface. To analyze the resulting interferograms of the surface we used the phase shifting analysis method by using a piezoelectric phase-shifter and Durango® interferometry software from Diffraction International™.

Short spatial filters with spherical lenses for high-power pulsed lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burdonov, K F; Soloviev, A A; Shaikin, A A

We report possible employment of short spatial filters based on spherical lenses in a pulsed laser source (neodymium glass, 300 J, 1 ns). The influence of the spherical aberration on the quality of output radiation and coefficient of conversion to the second harmonics is studied. The ultra-short aberration spatial filter of length 1.9 m with an aperture of 122 mm is experimentally tested. A considerable shortening of multi-cascade pump lasers for modern petawatt laser systems is demonstrated by the employment of short spatial filters without expensive aspherical optics. (elements of laser systems)

Ideal form of optical plasma lenses

NASA Astrophysics Data System (ADS)

Gordon, D. F.; Stamm, A. B.; Hafizi, B.; Johnson, L. A.; Kaganovich, D.; Hubbard, R. F.; Richardson, A. S.; Zhigunov, D.

2018-06-01

The canonical form of an optical plasma lens is a parabolic density channel. This form suffers from spherical aberrations, among others. Spherical aberration is partially corrected by adding a quartic term to the radial density profile. Ideal forms which lead to perfect focusing or imaging are obtained. The fields at the focus of a strong lens are computed with high accuracy and efficiency using a combination of eikonal and full Maxwell descriptions of the radiation propagation. The calculations are performed using a new computer propagation code, SeaRay, which is designed to transition between various solution methods as the beam propagates through different spatial regions. The calculations produce the full Maxwell vector fields in the focal region.

Modeling H2O and CO2 in Optically Thick Comets Using Asymmetric Spherical Coupled Escape Probability and Application to Comet C/2009 P1 Garradd Observations of CO, H2O, and CO2

NASA Astrophysics Data System (ADS)

Gersch, Alan M.; Feaga, Lori M.; A’Hearn, Michael F.

2018-02-01

We have adapted Coupled Escape Probability, a new exact method of solving radiative transfer problems, for use in asymmetrical spherical situations for use in modeling optically thick cometary comae. Here we present the extension of our model and corresponding results for two additional primary volatile species of interest, H2O and CO2, in purely theoretical comets. We also present detailed modeling and results for the specific examples of CO, H2O, and CO2 observations of C/2009 P1 Garradd by the Deep Impact flyby spacecraft.

Fabrication of an Optical Fiber Micro-Sphere with a Diameter of Several Tens of Micrometers.

PubMed

Yu, Huijuan; Huang, Qiangxian; Zhao, Jian

2014-06-25

A new method to fabricate an integrated optical fiber micro-sphere with a diameter within 100 µm, based on the optical fiber tapering technique and the Taguchi method is proposed. Using a 125 µm diameter single-mode (SM) optical fiber, an optical fiber taper with a cone angle is formed with the tapering technique, and the fabrication optimization of a micro-sphere with a diameter of less than 100 µm is achieved using the Taguchi method. The optimum combination of process factors levels is obtained, and the signal-to-noise ratio (SNR) of three quality evaluation parameters and the significance of each process factors influencing them are selected as the two standards. Using the minimum zone method (MZM) to evaluate the quality of the fabricated optical fiber micro-sphere, a three-dimensional (3D) numerical fitting image of its surface profile and the true sphericity are subsequently realized. From the results, an optical fiber micro-sphere with a two-dimensional (2D) diameter less than 80 µm, 2D roundness error less than 0.70 µm, 2D offset distance between the micro-sphere center and the fiber stylus central line less than 0.65 µm, and true sphericity of about 0.5 µm, is fabricated.

Radiatively driven relativistic spherical winds under relativistic radiative transfer

NASA Astrophysics Data System (ADS)

Fukue, J.

2018-05-01

We numerically investigate radiatively driven relativistic spherical winds from the central luminous object with mass M and luminosity L* under Newtonian gravity, special relativity, and relativistic radiative transfer. We solve both the relativistic radiative transfer equation and the relativistic hydrodynamical equations for spherically symmetric flows under the double-iteration processes, to obtain the intensity and velocity fields simultaneously. We found that the momentum-driven winds with scattering are quickly accelerated near the central object to reach the terminal speed. The results of numerical solutions are roughly fitted by a relation of \\dot{m}=0.7(Γ _*-1)\\tau _* β _* β _out^{-2.6}, where \\dot{m} is the mass-loss rate normalized by the critical one, Γ* the central luminosity normalized by the critical one, τ* the typical optical depth, β* the initial flow speed at the central core of radius R*, and βout the terminal speed normalized by the speed of light. This relation is close to the non-relativistic analytical solution, \\dot{m} = 2(Γ _*-1)\\tau _* β _* β _out^{-2}, which can be re-expressed as β _out^2/2 = (Γ _*-1)GM/c^2 R_*. That is, the present solution with small optical depth is similar to that of the radiatively driven free outflow. Furthermore, we found that the normalized luminosity (Eddington parameter) must be larger than unity for the relativistic spherical wind to blow off with intermediate or small optical depth, i.e. Γ _* ≳ \\sqrt{(1+β _out)^3/(1-β _out)}. We briefly investigate and discuss an isothermal wind.

An algorithm for localization of optical disturbances in turbid media using time-resolved diffuse optical tomography

NASA Astrophysics Data System (ADS)

Potlov, A. Yu.; Frolov, S. V.; Proskurin, S. G.

2018-04-01

Optical structure disturbances localization algorithm for time-resolved diffuse optical tomography of biological objects is described. The key features of the presented algorithm are: the initial approximation for the spatial distribution of the optical characteristics based on the Homogeneity Index and the assumption that all the absorbing and scattering inhomogeneities in an investigated object are spherical and have the same absorption and scattering coefficients. The described algorithm can be used in the brain structures diagnosis, in traumatology and optical mammography.

Phase shifting interferometer

DOEpatents

Sommargren, Gary E.

1999-01-01

An interferometer which has the capability of measuring optical elements and systems with an accuracy of .lambda./1000 where .lambda. is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about .lambda./50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. Whereas current interferometers illuminate the optic to be tested with an aberrated wavefront which also limits the accuracy of the measurement, this interferometer uses an essentially perfect spherical measurement wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms.

Phase shifting interferometer

DOEpatents

Sommargren, G.E.

1999-08-03

An interferometer is disclosed which has the capability of measuring optical elements and systems with an accuracy of {lambda}/1000 where {lambda} is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about {lambda}/50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. Whereas current interferometers illuminate the optic to be tested with an aberrated wavefront which also limits the accuracy of the measurement, this interferometer uses an essentially perfect spherical measurement wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms. 11 figs.

Reduced cost and improved figure of sapphire optical components

NASA Astrophysics Data System (ADS)

Walters, Mark; Bartlett, Kevin; Brophy, Matthew R.; DeGroote Nelson, Jessica; Medicus, Kate

2015-10-01

Sapphire presents many challenges to optical manufacturers due to its high hardness and anisotropic properties. Long lead times and high prices are the typical result of such challenges. The cost of even a simple 'grind and shine' process can be prohibitive. The high precision surfaces required by optical sensor applications further exacerbate the challenge of processing sapphire thereby increasing cost further. Optimax has demonstrated a production process for such windows that delivers over 50% time reduction as compared to traditional manufacturing processes for sapphire, while producing windows with less than 1/5 wave rms figure error. Optimax's sapphire production process achieves significant improvement in cost by implementation of a controlled grinding process to present the best possible surface to the polishing equipment. Following the grinding process is a polishing process taking advantage of chemical interactions between slurry and substrate to deliver excellent removal rates and surface finish. Through experiments, the mechanics of the polishing process were also optimized to produce excellent optical figure. In addition to reducing the cost of producing large sapphire sensor windows, the grinding and polishing technology Optimax has developed aids in producing spherical sapphire components to better figure quality. In addition to reducing the cost of producing large sapphire sensor windows, the grinding and polishing technology Optimax has developed aids in producing spherical sapphire components to better figure quality. Through specially developed polishing slurries, the peak-to-valley figure error of spherical sapphire parts is reduced by over 80%.

Near re-entrant dense pattern optical multipass cell

NASA Technical Reports Server (NTRS)

Silver, Joel A. (Inventor)

2007-01-01

A multiple pass optical cell and method comprising providing a pair of opposed mirrors, one cylindrical and one spherical, introducing light into the cell via an entrance mechanism, and extracting light from the cell via an exit mechanism, wherein the entrance mechanism and exit mechanism are coextensive or non-coextensive.

Optical aberrations measurement with a low cost optometric instrument

NASA Astrophysics Data System (ADS)

Furlan, Walter D.; Muñoz-Escrivá, L.; Pons, A.; Martínez-Corral, M.

2002-08-01

A simple experimental method for measuring optical aberrations of a single lens is proposed. The technique is based on the use of an optometric instrument employed for the assessment of the refractive state of the eye: the retinoscope. Experimental results for spherical aberration and astigmatism are obtained.

Crackle template based metallic mesh with highly homogeneous light transmission for high-performance transparent EMI shielding

PubMed Central

Han, Yu; Lin, Jie; Liu, Yuxuan; Fu, Hao; Ma, Yuan; Jin, Peng; Tan, Jiubin

2016-01-01

Our daily electromagnetic environment is becoming increasingly complex with the rapid development of consumer electronics and wireless communication technologies, which in turn necessitates the development of electromagnetic interference (EMI) shielding, especially for transparent components. We engineered a transparent EMI shielding film with crack-template based metallic mesh (CT-MM) that shows highly homogeneous light transmission and strong microwave shielding efficacy. The CT-MM film is fabricated using a cost-effective lift-off method based on a crackle template. It achieves a shielding effectiveness of ~26 dB, optical transmittance of ~91% and negligible impact on optical imaging performance. Moreover, high–quality CT-MM film is demonstrated on a large–calibre spherical surface. These excellent properties of CT-MM film, together with its advantages of facile large-area fabrication and scalability in processing on multi-shaped substrates, make CT-MM a powerful technology for transparent EMI shielding in practical applications. PMID:27151578

Forwardscattering corrections for optical extinction measurements in aerosol media. II - Polydispersions

NASA Technical Reports Server (NTRS)

Deepak, A.; Box, M. A.

1978-01-01

The paper presents a parametric study of the forwardscattering corrections for experimentally measured optical extinction coefficients in polydisperse particulate media, since some forward scattered light invariably enters, along with the direct beam, into the finite aperture of the detector. Forwardscattering corrections are computed by two methods: (1) using the exact Mie theory, and (2) the approximate Rayleigh diffraction formula for spherical particles. A parametric study of the dependence of the corrections on mode radii, real and imaginary parts of the complex refractive index, and half-angle of the detector's view cone has been carried out for three different size distribution functions of the modified gamma type. In addition, a study has been carried out to investigate the range of these parameters in which the approximate formulation is valid. The agreement is especially good for small-view cone angles and large particles, which improves significantly for slightly absorbing aerosol particles. Also discussed is the dependence of these corrections on the experimental design of the transmissometer systems.

Distributed Computing Architecture for Image-Based Wavefront Sensing and 2 D FFTs

NASA Technical Reports Server (NTRS)

Smith, Jeffrey S.; Dean, Bruce H.; Haghani, Shadan

2006-01-01

Image-based wavefront sensing (WFS) provides significant advantages over interferometric-based wavefi-ont sensors such as optical design simplicity and stability. However, the image-based approach is computational intensive, and therefore, specialized high-performance computing architectures are required in applications utilizing the image-based approach. The development and testing of these high-performance computing architectures are essential to such missions as James Webb Space Telescope (JWST), Terrestial Planet Finder-Coronagraph (TPF-C and CorSpec), and Spherical Primary Optical Telescope (SPOT). The development of these specialized computing architectures require numerous two-dimensional Fourier Transforms, which necessitate an all-to-all communication when applied on a distributed computational architecture. Several solutions for distributed computing are presented with an emphasis on a 64 Node cluster of DSPs, multiple DSP FPGAs, and an application of low-diameter graph theory. Timing results and performance analysis will be presented. The solutions offered could be applied to other all-to-all communication and scientifically computationally complex problems.

Spherical primary optical telescope (SPOT) segments

NASA Astrophysics Data System (ADS)

Hall, Christopher; Hagopian, John; DeMarco, Michael

2012-09-01

The spherical primary optical telescope (SPOT) project is an internal research and development program at NASA Goddard Space Flight Center. The goals of the program are to develop a robust and cost effective way to manufacture spherical mirror segments and demonstrate a new wavefront sensing approach for continuous phasing across the segmented primary. This paper focuses on the fabrication of the mirror segments. Significant cost savings were achieved through the design, since it allowed the mirror segments to be cast rather than machined from a glass blank. Casting was followed by conventional figuring at Goddard Space Flight Center. After polishing, the mirror segments were mounted to their composite assemblies. QED Technologies used magnetorheological finishing (MRF®) for the final figuring. The MRF process polished the mirrors while they were mounted to their composite assemblies. Each assembly included several magnetic invar plugs that extended to within an inch of the face of the mirror. As part of this project, the interaction between the MRF magnetic field and invar plugs was evaluated. By properly selecting the polishing conditions, MRF was able to significantly improve the figure of the mounted segments. The final MRF figuring demonstrates that mirrors, in the mounted configuration, can be polished and tested to specification. There are significant process capability advantes due to polishing and testing the optics in their final, end-use assembled state.

Assessment of the performance of a compact concentric spectrometer system for Atmospheric Differential Optical Absorption Spectroscopy

NASA Astrophysics Data System (ADS)

Whyte, C.; Leigh, R. J.; Lobb, D.; Williams, T.; Remedios, J. J.; Cutter, M.; Monks, P. S.

2009-08-01

A breadboard demonstrator of a novel UV/VIS grating spectrometer for atmospheric research has been developed based upon a concentric arrangement of a spherical meniscus lens, concave spherical mirror and curved diffraction grating suitable for a range of remote sensing applications from the ground or space. The spectrometer is compact and provides high optical efficiency and performance benefits over traditional instruments. The concentric design is capable of handling high relative apertures, owing to spherical aberration and coma being near zero at all surfaces. The design also provides correction for transverse chromatic aberration and distortion, in addition to correcting for the distortion called "smile", the curvature of the slit image formed at each wavelength. These properties render this design capable of superior spectral and spatial performance with size and weight budgets significantly lower than standard configurations. This form of spectrometer design offers the potential for an exceptionally compact instrument for differential optical absorption spectroscopy (DOAS) applications particularly from space (LEO, GEO orbits) and from HAPs or ground-based platforms. The breadboard demonstrator has been shown to offer high throughput and a stable Gaussian line shape with a spectral range from 300 to 450 nm at better than 0.5 nm resolution, suitable for a number of typical DOAS applications.

A new Schwarzschild optical system for two-dimensional EUV imaging of MRX plasmas

NASA Astrophysics Data System (ADS)

Bolgert, P.; Bitter, M.; Efthimion, P.; Hill, K. W.; Ji, H.; Myers, C. E.; Yamada, M.; Yoo, J.; Zweben, S.

2013-10-01

This poster describes the design and construction of a new Schwarzschild optical system for two-dimensional EUV imaging of plasmas. This optical system consists of two concentric spherical mirrors with radii R1 and R2, and is designed to operate with certain angles of incidence θ1 and θ2. The special feature of this system resides in the fact that all the rays passing through the system are tangential to a third concentric circle; it assures that the condition for Bragg reflection is simultaneously fulfilled at each point on the two reflecting surfaces if the spherical mirrors are replaced by spherical multi-layer structures. A prototype of this imaging system will be implemented in the Magnetic Reconnection Experiment (MRX) at PPPL to obtain two-dimensional EUV images of the plasma in the energy range from 18 to 62 eV; the relative intensity of the emitted radiation in this energy range was determined from survey measurements with a photodiode. It is thought that the radiation at these energies is due to Bremsstrahlung and line emission caused by suprathermal electrons. This research is supported by DoE Contract Number DE-AC02-09CH11466 and by the Center for Magnetic Self-Organization (CMSO).

History of Hubble Space Telescope (HST)

NASA Image and Video Library

1993-12-01

Astronaut Hoffman held the Hubble Space Telescope (HST) Wide Field/Planetary Camera-1 (WF/PC1) that was replaced by WF/PC2 in the cargo bay of the Space Shuttle orbiter Endeavour during Extravehicular Activity (EVA). The STS-61 mission was the first of the series of the HST servicing missions. Two months after its deployment in space, scientists detected a 2-micron spherical aberration in the primary mirror of the HST that affected the telescope's ability to focus faint light sources into a precise point. This imperfection was very slight, one-fiftieth of the width of a human hair. During four spacewalks, the STS-61 crew replaced the solar panel with its flexing problems; the WF/PC1 with WF/PC2, with built-in corrective optics; and the High-Speed Photometer with the Corrective Optics Space Telescope Axial Replacement (COSTAR) to correct the aberration for the remaining instruments. The purpose of the HST, the most complex and sensitive optical telescope ever made, is to study the cosmos from a low-Earth orbit for 15 years or more. The HST provides fine detail imaging, produces ultraviolet images and spectra, and detects very faint objects. The Marshall Space Flight Center had responsibility for design, development, and construction of the HST. The Perkin-Elmer Corporation, in Danbury, Cornecticut, developed the optical system and guidance sensors.

Tunable-Bandwidth Filter System

NASA Technical Reports Server (NTRS)

Bailey, John W.

2004-01-01

A tunable-bandwidth filter system (TBFS), now undergoing development, is intended to be part of a remote sensing multispectral imaging system that will operate in the visible and near infrared spectral region (wavelengths from 400 to 900 nm). Attributes of the TBFS include rapid tunability of the pass band over a wide wavelength range and high transmission efficiency. The TBFS is based on a unique integration of two pairs of broadband Raman reflection holographic filters with two rotating spherical lenses. In experiments, a prototype of the TBFS, was shown to be capable of spectral sampling of images in the visible range over a 200 nm spectral range with a spectral resolution of 30 nm. The figure depicts the optical layout of a prototype of the TBFS as part of a laboratory multispectral imaging system for the spectral sampling of color test images in two orthogonal polarizations. Each pair of broadband Raman reflection holographic filters is mounted at an equatorial plane between two halves of a spherical lens. The two filters in each pair are characterized by steep spectral slopes (equivalently, narrow spectral edges), no ripple or side lobes in their pass bands, and a few nanometers of non-overlapping wavelength range between their pass bands. Each spherical lens and thus the filter pair within it is rotated in order to rapidly tune its pass band. The rotations of are effected by electronically controlled, programmable, high-precision rotation stages. The rotations are coordinated by electronic circuits operating under overall supervision of a personal computer in order to obtain the desired variation of the overall pass bands with time. Embedding the filters inside the spherical lenses increases the range of the hologram incidence angles, making it possible to continuously tune the pass and stop bands of the filters over a wider wavelength range. In addition, each spherical lens also serves as part of the imaging optics: The telephoto lens focuses incoming light to a field stop that is also a focal point of each spherical lens. A correcting lens in front of the field stop compensates for the spherical aberration of the spherical lenses. The front surface of each spherical lens collimates the light coming from the field stop. After the collimated light passes through the filter in the spherical lens, the rear surface of the lens focuses the light onto a charge-coupled-device image detector.

Tunable-Bandwidth Filter System

NASA Technical Reports Server (NTRS)

Aye, Tin; Yu, Kevin; Dimov, Fedor; Savant, Gajendra

2006-01-01

A tunable-bandwidth filter system (TBFS), now undergoing development, is intended to be part of a remote-sensing multispectral imaging system that will operate in the visible and near infrared spectral region (wavelengths from 400 to 900 nm). Attributes of the TBFS include rapid tunability of the pass band over a wide wavelength range and high transmission efficiency. The TBFS is based on a unique integration of two pairs of broadband Raman reflection holographic filters with two rotating spherical lenses. In experiments, a prototype of the TBFS was shown to be capable of spectral sampling of images in the visible range over a 200-nm spectral range with a spectral resolution of .30 nm. The figure depicts the optical layout of a prototype of the TBFS as part of a laboratory multispectral imaging system for the spectral sampling of color test images in two orthogonal polarizations. Each pair of broadband Raman reflection holographic filters is mounted at an equatorial plane between two halves of a spherical lens. The two filters in each pair are characterized by steep spectral slopes (equivalently, narrow spectral edges), no ripple or side lobes in their pass bands, and a few nanometers of non-overlapping wavelength range between their pass bands. Each spherical lens and thus the filter pair within it is rotated in order to rapidly tune its pass band. The rotations of the lenses are effected by electronically controlled, programmable, high-precision rotation stages. The rotations are coordinated by electronic circuits operating under overall supervision of a personal computer in order to obtain the desired variation of the overall pass bands with time. Embedding the filters inside the spherical lenses increases the range of the hologram incidence angles, making it possible to continuously tune the pass and stop bands of the filters over a wider wavelength range. In addition, each spherical lens also serves as part of the imaging optics: The telephoto lens focuses incoming light to a field stop that is also a focal point of each spherical lens. A correcting lens in front of the field stop compensates for the spherical aberration of the spherical lenses. The front surface of each spherical lens collimates the light coming from the field stop. After the collimated light passes through the filter in the spherical lens, the rear surface of the lens focuses the light onto a charge-coupled-device image detector.

Influence of Shape and Gradient Refractive Index in the Accommodative Changes of Spherical Aberration in Nonhuman Primate Crystalline Lenses

PubMed Central

de Castro, Alberto; Birkenfeld, Judith; Maceo, Bianca; Manns, Fabrice; Arrieta, Esdras; Parel, Jean-Marie; Marcos, Susana

2013-01-01

Purpose. To estimate changes in surface shape and gradient refractive index (GRIN) profile in primate lenses as a function of accommodation. To quantify the contribution of surface shape and GRIN to spherical aberration changes with accommodation. Methods. Crystalline lenses from 15 cynomolgus monkeys were studied in vitro under different levels of accommodation produced by a stretching system. Lens shape was obtained from optical coherence tomography (OCT) cross-sectional images. The GRIN was reconstructed with a search algorithm using the optical path measured from OCT images and the measured back focal length. The spherical aberration of the lens was estimated as a function of accommodation using the reconstructed GRIN and a homogeneous refractive index. Results. The lens anterior and posterior radii of curvature decreased with increasing lens power. Both surfaces exhibited negative asphericities in the unaccommodated state. The anterior surface conic constant shifted toward less negative values with accommodation, while the value of the posterior remained constant. GRIN parameters remained constant with accommodation. The lens spherical aberration with GRIN distribution was negative and higher in magnitude than that with a homogeneous equivalent refractive index (by 29% and 53% in the unaccommodated and fully accommodated states, respectively). Spherical aberration with the equivalent refractive index shifted with accommodation toward negative values (−0.070 μm/diopter [D]), but the reconstructed GRIN shifted it farther (−0.124 μm/D). Conclusions. When compared with the lens with the homogeneous equivalent refractive index, the reconstructed GRIN lens has more negative spherical aberration and a larger shift toward more negative values with accommodation. PMID:23927893

Comparison of three techniques in measuring progressive addition lenses.

PubMed

Huang, Ching-Yao; Raasch, Thomas W; Yi, Allen Y; Sheedy, James E; Andre, Brett; Bullimore, Mark A

2012-11-01

To measure progressive addition lenses (PALs) by three techniques and to compare the differences across techniques. Five contemporary PALs (Varilux Comfort Enhanced, Varilux Physio Enhanced, Hoya Lifestyle, Shamir Autograph, and Zeiss individual) with plano distance power and a +2.00 diopters (D) add were evaluated under the condition of lateral displacement of the lens (no rotation and no tilt) using three methods. A Hartmann-Shack wavefront sensor (HSWFS) on a custom-built optical bench was used to capture and measure wavefront aberrations. A Rotlex Class Plus lens analyzer operating as a moiré interferometer was used to measure spherical and cylindrical powers. A coordinate measuring machine (CMM) was used to measure front and back surfaces of PALs and converted to desired optical properties. The data were analyzed with MATLAB programs. Contour plots of spherical equivalent power, cylindrical power, and higher-order aberrations (HOAs) in all PALs were generated to compare their differences. The differences in spherical equivalent and cylinder at distance, near, and progressive corridor areas among the HSWFS, Rotlex, and CMM methods were close to zero in all five PALs. The maximum differences are approximately 0.50 D and located below the near power zone and the edge areas of the lens when comparing the HSWFS and CMM with the Rotlex. HOAs measured both by the HSWFS and CMM were highest in the corridor area and the area surrounding the near zone in all PALs. The HOAs measured by the CMM were lower than those from the HSWFS by 0.02 to 0.04 μm. The three measurement methods are comparable for measuring spherical and cylindrical power across PALs. The non-optical method, CMM, can be used to evaluate the optical properties of a PAL by measuring front and back surface height measurements, although its estimates of HOAs are lower than those from the HSWFS.

Superficial Macromolecular Arrays on the Cell Wall of Spirillum putridiconchylium

PubMed Central

Beveridge, T. J.; Murray, R. G. E.

1974-01-01

Electron microscopy of the cell envelope of Spirillum putridiconchylium, using negatively stained, thin-sectioned, and replicated freeze-etched preparations, showed two superficial wall layers forming a complex macromolecular pattern on the external surface. The outer structured layer was a linear array of particles overlying an inner tetragonal array of larger subunits. They were associated in a very regular fashion, and the complex was bonded to the outer, pitted surface of the lipopolysaccharide tripartite layer of the cell wall. The relationship of the components of the two structured layers was resolved with the aid of optical diffraction, combined with image filtering and reconstruction and linear and rotary integration techniques. The outer structural layer consisted of spherical 1.5-nm units set in double lines determined by the size and arrangement of 6- by 3-nm inner structural layer subunits, which bore one outer structural layer unit on each outer corner. The total effect of this arrangement was a double-ridged linear structure that was evident in surface replicas and negatively stained fragments of the whole wall. The packing of these units was not square but skewed by 2° off the perpendicular so that the “unit array” described by optical diffraction and linear integration appeared to be a deformed tetragon. The verity of the model was checked by using a photographically reduced image to produce an optical diffraction pattern for comparison with that of the actual layers. The correspondence was nearly perfect. Images PMID:4137219

Nuclear matter parameters and optical model analysis of proton elastic scattering on the doubly magic nucleus 40Ca

NASA Astrophysics Data System (ADS)

Khalaf, A. M.; Khalifa, M. M.; Solieman, A. H. M.; Comsan, M. N. H.

2018-01-01

Owing to its doubly magic nature having equal numbers of protons and neutrons, the 40Ca nuclear scattering can be successfully described by the optical model that assumes a spherical nuclear potential. Therefore, optical model analysis was employed to calculate the elastic scattering cross section for p +40Ca interaction at energies from 9 to 22 MeV as well as the polarization at energies from 10 to 18.2 MeV. New optical model parameters (OMPs) were proposed based on the best fitting to experimental data. It is found that the best fit OMPs depend on the energy by smooth relationships. The results were compared with other OMPs sets regarding their chi square values (χ2). The obtained OMP's set was used to calculate the volume integral of the potentials and the root mean square (rms) value of nuclear matter radius of 40Ca. In addition, 40Ca bulk nuclear matter properties were discussed utilizing both the obtained rms radius and the Thomas-Fermi rms radius calculated using spherical Hartree-Fock formalism employing Skyrme type nucleon-nucleon force. The nuclear scattering SCAT2000 FORTRAN code was used for the optical model analysis.

Structural and morphological study of chemically synthesized CdSe thin films

NASA Astrophysics Data System (ADS)

Agrawal, P.; Singh, Randhir; Sharma, Jeewan; Sachdeva, M.; Singh, Anupinder; Bhargava, A.

2018-05-01

Nanocrystalline CdSe thin films were prepared by Chemical Bath Deposition (CBD) method using potassium nitrilo-triacetic acid cadmium complex and sodium selenosulphite. The as deposited films were red in color, uniform and well adherent to the glass substrate. These films were strongly dependent on the deposition parameters such as bath composition, deposition temperature and time. Films were annealed at 350 °C for four hours. The morphological, structural and optical properties were studied using X-ray diffraction (XRD), UV-VIS spectrophotometer measurements, scanning electron microscopy and atomic force microscopy. The XRD analysis confirmed that films are predominantly in hexagonal phase. Scanning electron micrograph shows that the grains are uniformly spread all over the film and each grain contains many nanocrystals with spherical shapes.

History of Hubble Space Telescope (HST)

NASA Image and Video Library

1994-01-01

A comparison image of the M100 Galactic Nucleus, taken by the Hubble Space Telescope (HST) Wide Field Planetary Camera-1 (WF/PC1) and Wide Field Planetary Camera-2 (WF/PC2). The HST was placed in a low-Earth orbit by the Space Shuttle Discovery, STS-31 mission, in April 1990. Two months after its deployment in space, scientists detected a 2-micron spherical aberration in the primary mirror of the HST that affected the telescope's ability to focus faint light sources into a precise point. This imperfection was very slight, one-fiftieth of the width of a human hair. During four spacewalks, the STS-61 crew replaced the solar panel with its flexing problems; the WF/PC1 with the WF/PC2, with built-in corrective optics; and the High-Speed Photometer with the Corrective Optics Space Telescope Axial Replacement (COSTAR), to correct the aberration for the remaining instruments. The purpose of the HST, the most complex and sensitive optical telescope ever made, is to study the cosmos from a low-Earth orbit for 15 years or more. The HST provides fine detail imaging, produces ultraviolet images and spectra, and detects very faint objects.

History of Hubble Space Telescope (HST)

NASA Image and Video Library

1990-04-25

In this photograph, the Hubble Space Telescope (HST) was being deployed on April 25, 1990. The photograph was taken by the IMAX Cargo Bay Camera (ICBC) mounted in a container on the port side of the Space Shuttle orbiter Discovery (STS-31 mission). The purpose of the HST, the most complex and sensitive optical telescope ever made, is to study the cosmos from a low-Earth orbit for 15 years or more. The HST provides fine detail imaging, produces ultraviolet images and spectra, and detects very faint objects. Two months after its deployment in space, scientists detected a 2-micron spherical aberration in the primary mirror of the HST that affected the telescope's ability to focus faint light sources into a precise point. This imperfection was very slight, one-fiftieth of the width of a human hair. A scheduled Space Service servicing mission (STS-61) in 1993 permitted scientists to correct the problem. During four spacewalks, new instruments were installed into the HST that had optical corrections. The Marshall Space Flight Center had responsibility for design, development, and construction of the HST. The Perkin-Elmer Corporation, in Danbury, Cornecticut, developed the optical system and guidance sensors. Photo Credit: NASA/Smithsonian Institution/Lockheed Corporation.

Artificial neural network for the determination of Hubble Space Telescope aberration from stellar images

NASA Technical Reports Server (NTRS)

Barrett, Todd K.; Sandler, David G.

1993-01-01

An artificial-neural-network method, first developed for the measurement and control of atmospheric phase distortion, using stellar images, was used to estimate the optical aberration of the Hubble Space Telescope. A total of 26 estimates of distortion was obtained from 23 stellar images acquired at several secondary-mirror axial positions. The results were expressed as coefficients of eight orthogonal Zernike polynomials: focus through third-order spherical. For all modes other than spherical the measured aberration was small. The average spherical aberration of the estimates was -0.299 micron rms, which is in good agreement with predictions obtained when iterative phase-retrieval algorithms were used.

Electronic scattering, focusing, and resonance by a spherical barrier in Weyl semimetals

NASA Astrophysics Data System (ADS)

Lu, Ming; Zhang, Xiao-Xiao

2018-05-01

We solve the Weyl electron scattered by a spherical step potential barrier. Tuning the incident energy and the potential radius, one can enter both quasiclassical and quantum regimes. Transport features related to far-field currents and integrated cross sections are studied to reveal the preferred forward scattering. In the quasiclassical regime, a strong focusing effect along the incident spherical axis is found in addition to optical caustic patterns. In the quantum regime, at energies of successive angular momentum resonances, a polar aggregation of electron density is found inside the potential. The findings will be useful in transport studies and electronic lens applications in Weyl systems.

Optical properties of hybrid spherical nanoclusters containing quantum emitters and metallic nanoparticles

NASA Astrophysics Data System (ADS)

Yannopapas, V.; Paspalakis, E.

2018-05-01

We study theoretically the optical response of a hybrid spherical cluster containing quantum emitters and metallic nanoparticles. The quantum emitters are modeled as two-level quantum systems whose dielectric function is obtained via a density matrix approach wherein the modified spontaneous emission decay rate at the position of each quantum emitter is calculated via the electromagnetic Green's tensor. The problem of light scattering off the hybrid cluster is solved by employing the coupled-dipole method. We find, in particular, that the presence of the quantum emitters in the cluster, even in small fractions, can significantly alter the absorption and extinction spectra of the sole cluster of the metallic nanoparticles, where the corresponding electromagnetic modes can have a weak plexcitonic character under suitable conditions.

Single-axis four-mirror system: large spherical primary and small fields

NASA Astrophysics Data System (ADS)

Baranne, Andre

1998-08-01

A catoptric corrector of modest size can be used for large spherical primaries, easily integrated at the prime focus, this corrector gives back to the system, aspect and properties of 2-mirrors classical telescopes. In the last few years, progress in active and adaptative optics makes possible a lot of things, progress in measuring distances, new ideas on optical coatings, new materials and so on in a near future, all that makes the instrumentalist dreamy It is said that nobody knows today if the size of 3rd millennium telescopes will be limited or not by a theoretical, physical or technical phenomenon, thus let us imagine but with thoughtfulness because our projects will be surely restricted by financial considerations

Comparison of Color Fundus Photography, Infrared Fundus Photography, and Optical Coherence Tomography in Detecting Retinal Hamartoma in Patients with Tuberous Sclerosis Complex

PubMed Central

Bai, Da-Yong; Wang, Xu; Zhao, Jun-Yang; Li, Li; Gao, Jun; Wang, Ning-Li

2016-01-01

Background: A sensitive method is required to detect retinal hamartomas in patients with tuberous sclerosis complex (TSC). The aim of the present study was to compare the color fundus photography, infrared imaging (IFG), and optical coherence tomography (OCT) in the detection rate of retinal hamartoma in patients with TSC. Methods: This study included 11 patients (22 eyes) with TSC, who underwent color fundus photography, IFG, and spectral-domain OCT to detect retinal hamartomas. TSC1 and TSC2 mutations were tested in eight patients. Results: The mean age of the 11 patients was 8.0 ± 2.1 years. The mean spherical equivalent was −0.55 ± 1.42 D by autorefraction with cycloplegia. In 11 patients (22 eyes), OCT, infrared fundus photography, and color fundus photography revealed 26, 18, and 9 hamartomas, respectively. The predominant hamartoma was type I (55.6%). All the hamartomas that detected by color fundus photography or IFG can be detected by OCT. Conclusion: Among the methods of color fundus photography, IFG, and OCT, the OCT has higher detection rate for retinal hamartoma in TSC patients; therefore, OCT might be promising for the clinical diagnosis of TSC. PMID:27174333

Condenser for illuminating a ringfield camera with synchrotron emission light

DOEpatents

Sweatt, W.C.

1996-04-30

The present invention relates generally to the field of condensers for collecting light from a synchrotron radiation source and directing the light into a ringfield of a lithography camera. The present invention discloses a condenser comprising collecting, processing, and imaging optics. The collecting optics are comprised of concave and convex spherical mirrors that collect the light beams. The processing optics, which receive the light beams, are comprised of flat mirrors that converge and direct the light beams into a real entrance pupil of the camera in a symmetrical pattern. In the real entrance pupil are located flat mirrors, common to the beams emitted from the preceding mirrors, for generating substantially parallel light beams and for directing the beams toward the ringfield of a camera. Finally, the imaging optics are comprised of a spherical mirror, also common to the beams emitted from the preceding mirrors, images the real entrance pupil through the resistive mask and into the virtual entrance pupil of the camera. Thus, the condenser is comprised of a plurality of beams with four mirrors corresponding to a single beam plus two common mirrors. 9 figs.

Condenser for illuminating a ringfield camera with synchrotron emission light

DOEpatents

Sweatt, William C.

1996-01-01

The present invention relates generally to the field of condensers for collecting light from a synchrotron radiation source and directing the light into a ringfield of a lithography camera. The present invention discloses a condenser comprising collecting, processing, and imaging optics. The collecting optics are comprised of concave and convex spherical mirrors that collect the light beams. The processing optics, which receive the light beams, are comprised of flat mirrors that converge and direct the light beams into a real entrance pupil of the camera in a symmetrical pattern. In the real entrance pupil are located flat mirrors, common to the beams emitted from the preceding mirrors, for generating substantially parallel light beams and for directing the beams toward the ringfield of a camera. Finally, the imaging optics are comprised of a spherical mirror, also common to the beams emitted from the preceding mirrors, images the real entrance pupil through the resistive mask and into the virtual entrance pupil of the camera. Thus, the condenser is comprised of a plurality of beams with four mirrors corresponding to a single beam plus two common mirrors.

Accounting for optical errors in microtensiometry.

PubMed

Hinton, Zachary R; Alvarez, Nicolas J

2018-09-15

Drop shape analysis (DSA) techniques measure interfacial tension subject to error in image analysis and the optical system. While considerable efforts have been made to minimize image analysis errors, very little work has treated optical errors. There are two main sources of error when considering the optical system: the angle of misalignment and the choice of focal plane. Due to the convoluted nature of these sources, small angles of misalignment can lead to large errors in measured curvature. We demonstrate using microtensiometry the contributions of these sources to measured errors in radius, and, more importantly, deconvolute the effects of misalignment and focal plane. Our findings are expected to have broad implications on all optical techniques measuring interfacial curvature. A geometric model is developed to analytically determine the contributions of misalignment angle and choice of focal plane on measurement error for spherical cap interfaces. This work utilizes a microtensiometer to validate the geometric model and to quantify the effect of both sources of error. For the case of a microtensiometer, an empirical calibration is demonstrated that corrects for optical errors and drastically simplifies implementation. The combination of geometric modeling and experimental results reveal a convoluted relationship between the true and measured interfacial radius as a function of the misalignment angle and choice of focal plane. The validated geometric model produces a full operating window that is strongly dependent on the capillary radius and spherical cap height. In all cases, the contribution of optical errors is minimized when the height of the spherical cap is equivalent to the capillary radius, i.e. a hemispherical interface. The understanding of these errors allow for correct measure of interfacial curvature and interfacial tension regardless of experimental setup. For the case of microtensiometry, this greatly decreases the time for experimental setup and increases experiential accuracy. In a broad sense, this work outlines the importance of optical errors in all DSA techniques. More specifically, these results have important implications for all microscale and microfluidic measurements of interface curvature. Copyright © 2018 Elsevier Inc. All rights reserved.

Anomalous optical scattering from intersecting fine particles

NASA Astrophysics Data System (ADS)

Paley, Alina V.; Radchik, Alex V.; Smith, Geoffrey B.

1995-09-01

There are many areas of science and technology where the scattering of electromagnetic waves by clusters or merging particles are of interest. The merging particles under study might be inclusions in high-density composites, liquid drops, biological cells, macroscopic ceramic particles, etc. As intersecting particles are bounded by a complex physical surface, the problem of scattering from these particles valid for any degree of merging, including touching, and for arbitrary materials of the constituents, has received limited attention. Here we present solutions which are valid and exact in the long wavelength limit compared with the size of intersecting spherical particles and cardioidal particles of similar dimensions. Both shapes are almost coincident everywhere except in the region of intersection. We treat the case when the waves are polarized along the common axis (longitudinal field). The solutions of Laplace's equation are integrals (spheres) or sums (cardioids) over continuous or discrete eigenvalue spectra respectively. The spectral dependencies of the resulting extinction coefficients and the scattering for the spherical and cardioidal particles are quite distinct. There is an enormous difference in the magnitude of absorption responses. Overall the cardioidal particle behaves as if it is almost invisible in terms of effects on the external field for a very broad band of optical frequencies. THe latter result was checked for a number of dielectric permittivities and seems to be universal. It scatters far more weakly than the isolated sphere. In constrast the intersecting sphere has an extinction band which is broad and is much enhanced at longer wavelegnths relative to the simple sphere. This result has significant implications for the design of surfaces with minimum scattering.

A pyrazolyl-based thiolato single-source precursor for the selective synthesis of isotropic copper-deficient copper(I) sulfide nanocrystals: synthesis, optical and photocatalytic activity

NASA Astrophysics Data System (ADS)

Mondal, Gopinath; Santra, Ananyakumari; Bera, Pradip; Acharjya, Moumita; Jana, Sumanta; Chattopadhyay, Dipankar; Mondal, Anup; Seok, Sang Il; Bera, Pulakesh

2016-10-01

Hexagonal copper-deficient copper(I) sulfide (Cu2- x S, x = 0.03, 0.2) nanocrystals (NCs) are synthesized from a newly prepared single-source precursor (SP), [Cu(bdpa)2][CuCl2], where bdpa is benzyl 3,5-dimethyl-pyrazole-1-carbodithioate. The SP is crystallized with space group Pī and possesses a distorted tetrahedron structure with a CuN2S2 chromophore where the central copper is in +1 oxidation state. Distortion in copper(I) structure and the low decomposition temperature of SP make it favorable for the low-temperature solvent-assisted selective growth of high-copper content sulfides. The nucleation and growth of Cu2- x S ( x = 0.03, 0.2) are effectively controlled by the SP and the solvent in the solvothermal decomposition process. During decomposition, fragment benzyl thiol (PhCH2SH) from SP effectively passivates the nucleus leading to spherical nanocrystals. Further, solvent plays an important role in the selective thermochemical transformation of CuI-complex to Cu2- x S ( x = 0.03, 0.2) NCs. The chelating binders (solvent) like ethylene diamine (EN) and ethylene glycol (EG) prefer to form spherical Cu1.97S nanoparticles (djurleite), whereas nonchelating hydrazine hydrate (HH) shows the tendency to furnish hexagonal platelets of copper-deficient Cu1.8S. The optical band gap values (2.25-2.50 eV) show quantum confinement effect in the structure. The synthesized NCs display excellent catalytic activity ( 87 %) toward photodegradation of organic dyes like Congo Red (CR) and Methylene Blue (MB).

Retrieval of Aerosol Optical Properties from Ground-Based Remote Sensing Measurements: Aerosol Asymmetry Factor and Single Scattering Albedo

NASA Astrophysics Data System (ADS)

Qie, L.; Li, Z.; Li, L.; Li, K.; Li, D.; Xu, H.

2018-04-01

The Devaux-Vermeulen-Li method (DVL method) is a simple approach to retrieve aerosol optical parameters from the Sun-sky radiance measurements. This study inherited the previous works of retrieving aerosol single scattering albedo (SSA) and scattering phase function, the DVL method was modified to derive aerosol asymmetric factor (g). To assess the algorithm performance at various atmospheric aerosol conditions, retrievals from AERONET observations were implemented, and the results are compared with AERONET official products. The comparison shows that both the DVL SSA and g were well correlated with those of AERONET. The RMSD and the absolute value of MBD deviations between the SSAs are 0.025 and 0.015 respectively, well below the AERONET declared SSA uncertainty of 0.03 for all wavelengths. For asymmetry factor g, the RMSD deviations are smaller than 0.02 and the absolute values of MBDs smaller than 0.01 at 675, 870 and 1020 nm bands. Then, considering several factors probably affecting retrieval quality (i.e. the aerosol optical depth (AOD), the solar zenith angle, and the sky residual error, sphericity proportion and Ångström exponent), the deviations for SSA and g of these two algorithms were calculated at varying value intervals. Both the SSA and g deviations were found decrease with the AOD and the solar zenith angle, and increase with sky residual error. However, the deviations do not show clear sensitivity to the sphericity proportion and Ångström exponent. This indicated that the DVL algorithm is available for both large, non-spherical particles and spherical particles. The DVL results are suitable for the evaluation of aerosol direct radiative effects of different aerosol types.

The Design and Analysis of Electrically Large Custom-Shaped Reflector Antennas

DTIC Science & Technology

2013-06-01

GEO) satellite data are imported into STK and plotted to visualize the regions of the sky that the spherical reflector must have line of sight for...Magnetic Conductor PO Physical Optics STK Systems Tool Kit TE Transverse Electric xvii Acronym Definition TLE Two Line Element TM Transverse Magnetic...study for the spherical reflector, Systems Tool Kit ( STK ) software from Analytical Graphics Inc. (AGI) is used. In completing the cross-shaped

Optical characterization of multi-scale morphologically complex heterogeneous media - Application to snow with soot impurities

NASA Astrophysics Data System (ADS)

Dai, Xiaoyu; Haussener, Sophia

2018-02-01

A multi-scale methodology for the radiative transfer analysis of heterogeneous media composed of morphologically-complex components on two distinct scales is presented. The methodology incorporates the exact morphology at the various scales and utilizes volume-averaging approaches with the corresponding effective properties to couple the scales. At the continuum level, the volume-averaged coupled radiative transfer equations are solved utilizing (i) effective radiative transport properties obtained by direct Monte Carlo simulations at the pore level, and (ii) averaged bulk material properties obtained at particle level by Lorenz-Mie theory or discrete dipole approximation calculations. This model is applied to a soot-contaminated snow layer, and is experimentally validated with reflectance measurements of such layers. A quantitative and decoupled understanding of the morphological effect on the radiative transport is achieved, and a significant influence of the dual-scale morphology on the macroscopic optical behavior is observed. Our results show that with a small amount of soot particles, of the order of 1ppb in volume fraction, the reduction in reflectance of a snow layer with large ice grains can reach up to 77% (at a wavelength of 0.3 μm). Soot impurities modeled as compact agglomerates yield 2-3% lower reduction of the reflectance in a thick show layer compared to snow with soot impurities modeled as chain-like agglomerates. Soot impurities modeled as equivalent spherical particles underestimate the reflectance reduction by 2-8%. This study implies that the morphology of the heterogeneities in a media significantly affects the macroscopic optical behavior and, specifically for the soot-contaminated snow, indicates the non-negligible role of soot on the absorption behavior of snow layers. It can be equally used in technical applications for the assessment and optimization of optical performance in multi-scale media.

Design and Optimization of the SPOT Primary Mirror Segment

NASA Technical Reports Server (NTRS)

Budinoff, Jason G.; Michaels, Gregory J.

2005-01-01

The 3m Spherical Primary Optical Telescope (SPOT) will utilize a single ring of 0.86111 point-to-point hexagonal mirror segments. The f2.85 spherical mirror blanks will be fabricated by the same replication process used for mass-produced commercial telescope mirrors. Diffraction-limited phasing will require segment-to-segment radius of curvature (ROC) variation of approx.1 micron. Low-cost, replicated segment ROC variations are estimated to be almost 1 mm, necessitating a method for segment ROC adjustment & matching. A mechanical architecture has been designed that allows segment ROC to be adjusted up to 400 microns while introducing a minimum figure error, allowing segment-to-segment ROC matching. A key feature of the architecture is the unique back profile of the mirror segments. The back profile of the mirror was developed with shape optimization in MSC.Nastran(TradeMark) using optical performance response equations written with SigFit. A candidate back profile was generated which minimized ROC-adjustment-induced surface error while meeting the constraints imposed by the fabrication method. Keywords: optimization, radius of curvature, Pyrex spherical mirror, Sigfit

Four-zone varifocus mirrors with adaptive control of primary and higher-order spherical aberration

PubMed Central

Lukes, Sarah J.; Downey, Ryan D.; Kreitinger, Seth T.; Dickensheets, David L.

2017-01-01

Electrostatically actuated deformable mirrors with four concentric annular electrodes can exert independent control over defocus as well as primary, secondary, and tertiary spherical aberration. In this paper we use both numerical modeling and physical measurements to characterize recently developed deformable mirrors with respect to the amount of spherical aberration each can impart, and the dependence of that aberration control on the amount of defocus the mirror is providing. We find that a four-zone, 4 mm diameter mirror can generate surface shapes with arbitrary primary, secondary, and tertiary spherical aberration over ranges of ±0.4, ±0.2, and ±0.15 μm, respectively, referred to a non-normalized Zernike polynomial basis. We demonstrate the utility of this mirror for aberration-compensated focusing of a high NA optical system. PMID:27409212

Numerical analysis of electrically tunable aspherical optofluidic lenses.

PubMed

In this work, we use the numerical simulation platform Zemax to investigate the optical properties of electrically tunable aspherical liquid lenses, as we recently reported in an experimental study [ K. Mishra C. Murade B. Carreel I. Roghair J. M. Oh G. Manukyan D. van den Ende F. Mugele , "Optofluidic lens with tunable focal length and asphericity," Sci. Rep.4, 6378 (2014)]. Based on the measured lens profiles in the presence of an inhomogeneous electric field and the geometry of the optical device, we calculate the optical aberrations, focusing in particular on the Z11 Zernike coefficient of spherical aberration obtained at zero defocus (Z4). Focal length and spherical aberrations are calculated for a wide range of control parameters (fluid pressure and electric field), parallel with the experimental results. Similarly, the modulation transfer function (MTF), image spot diagrams, Strehl's ratio, and peak-to-valley (P-V) and root mean square (RMS) wavefront errors are calculated to quantify the performance of our aspherical liquid lenses. We demonstrate that the device concept allows compensation for a wide range of spherical aberrations encountered in optical systems.; Mishra, Kartikeya; Mugele, Frieder

2016-06-27

In this work, we use the numerical simulation platform Zemax to investigate the optical properties of electrically tunable aspherical liquid lenses, as we recently reported in an experimental study [ K. Mishra C. Murade B. Carreel I. Roghair J. M. Oh G. Manukyan D. van den Ende F. Mugele , "Optofluidic lens with tunable focal length and asphericity," Sci. Rep.4, 6378 (2014)]. Based on the measured lens profiles in the presence of an inhomogeneous electric field and the geometry of the optical device, we calculate the optical aberrations, focusing in particular on the Z11 Zernike coefficient of spherical aberration obtained at zero defocus (Z4). Focal length and spherical aberrations are calculated for a wide range of control parameters (fluid pressure and electric field), parallel with the experimental results. Similarly, the modulation transfer function (MTF), image spot diagrams, Strehl's ratio, and peak-to-valley (P-V) and root mean square (RMS) wavefront errors are calculated to quantify the performance of our aspherical liquid lenses. We demonstrate that the device concept allows compensation for a wide range of spherical aberrations encountered in optical systems.

Investigation on plasmonic responses in multilayered nanospheres including asymmetry and spatial nonlocal effects

NASA Astrophysics Data System (ADS)

Dong, Tianyu; Shi, Yi; Liu, Hui; Chen, Feng; Ma, Xikui; Mittra, Raj

2017-12-01

In this work, we present a rigorous approach for analyzing the optical response of multilayered spherical nano-particles comprised of either plasmonic metal or dielectric, when there is no longer radial symmetry and when nonlocality is included. The Lorenz-Mie theory is applied, and a linearized hydrodynamic Drude model as well as the general nonlocal optical response model for the metals are employed. Additional boundary conditions, viz., the continuity of normal components of polarization current density and the continuity of first-order pressure of free electron density, respectively, are incorporated when handling interfaces involving metals. The application of spherical addition theorems, enables us to express a spherical harmonic about one origin to spherical harmonics about a different origin, and leads to a linear system of equations for the inward- and outward-field modal coefficients for all the layers in the nanoparticle. Scattering matrices at interfaces are obtained and cascaded to obtain the expansion coefficients, to yield the final solution. Through extensive modelling of stratified concentric and eccentric metal-involved spherical nanoshells illuminating by a plane wave, we show that, within a nonlocal description, significant modifications of plasmonic response appear, e.g. a blue-shift in the extinction / scattering spectrum and a broadening spectrum of the resonance. In addition, it has been demonstrated that core-shell nanostructures provide an option for tunable Fano-resonance generators. The proposed method shows its capability and flexibility to analyze the nonlocal response of eccentric hybrid metal-dielectric multilayer structures as well as adjoined metal-involved nanoparticles, even when the number of layers is large.

Fish Tank Optics.

ERIC Educational Resources Information Center

McCausland, Stuart; Allard, Brian

1997-01-01

Describes procedures for a demonstration of the focal length of spherical lenses and mirrors using an aquarium, a flashlight, and nondairy creamer. Enables nonquantitative three-dimensional observation of these phenomena. (DDR)

Calculation of Thermally-Induced Displacements in Spherically Domed Ion Engine Grids

NASA Technical Reports Server (NTRS)

Soulas, George C.

2006-01-01

An analytical method for predicting the thermally-induced normal and tangential displacements of spherically domed ion optics grids under an axisymmetric thermal loading is presented. A fixed edge support that could be thermally expanded is used for this analysis. Equations for the displacements both normal and tangential to the surface of the spherical shell are derived. A simplified equation for the displacement at the center of the spherical dome is also derived. The effects of plate perforation on displacements and stresses are determined by modeling the perforated plate as an equivalent solid plate with modified, or effective, material properties. Analytical model results are compared to the results from a finite element model. For the solid shell, comparisons showed that the analytical model produces results that closely match the finite element model results. The simplified equation for the normal displacement of the spherical dome center is also found to accurately predict this displacement. For the perforated shells, the analytical solution and simplified equation produce accurate results for materials with low thermal expansion coefficients.

Phase conjugate Twyman-Green interferometer for testing spherical surfaces and lenses and for measuring refractive indices of liquids or solid transparent materials

NASA Technical Reports Server (NTRS)

Shukla, R. P.; Dokhanian, Mostafa; Venkateswarlu, Putcha; George, M. C.

1990-01-01

The present paper describes an application of a phase conjugate Twyman-Green interferometer using barium titanate as a self-pumping mirror for testing optical components like concave and convex spherical mirrors and lenses. The aberrations introduced by the beam splitter while testing concave or convex spherical mirrors of large aperture are automatically eliminated due to self-focussing property of the phase conjugate mirror. There is no necessity for a good spherical surface as a reference surface unlike in classical Twyman-Green interferometer or Williams interferometer. The phase conjugate Twyman Green interferometer with a divergent illumination can be used as a test plate for checking spherical surfaces. A nondestructive technique for measuring the refractive indices of a Fabry Perot etalon by using a phase conjugate interferometer is also suggested. The interferometer is found to be useful for measuring the refractive indices of liquids and solid transparent materials with an accuracy of the order of + or - 0.0004.

Bragg x-ray optics for imaging spectroscopy of plasma microsources.

PubMed

Pikuz, T A; Ya Faenov, A; Pikuz, S A; Romanova, V M; Shelkovenko, T A

1995-01-01

Bragg x-ray optics based on crystals with transmission and reflection properties bent on cylindrical or spherical surfaces are discussed. Applications of such optics for obtaining one- and two-dimensional monochromatic images of different plasma sources in the wide spectral range 1-20 Å are described. Samples of spectra obtained with spectral resolution of up to λ/Δλ ~ 10,000 and spatial resolution of up to 18 μm are presented.

Rational design of Raman-labeled nanoparticles for a dual-modality, light scattering immunoassay on a polystyrene substrate.

PubMed

Israelsen, Nathan D; Wooley, Donald; Hanson, Cynthia; Vargis, Elizabeth

2016-01-01

Surface-enhanced Raman scattering (SERS) is a powerful light scattering technique that can be used for sensitive immunoassay development and cell labeling. A major obstacle to using SERS is the complexity of fabricating SERS probes since they require nanoscale characterization and optical uniformity. The light scattering response of SERS probes may also be modulated by the substrate used for SERS analysis. A typical SERS substrate such as quartz can be expensive. Polystyrene is a cheaper substrate option but can decrease the SERS response due to interfering Raman emission peaks and high background fluorescence. The goal of this research is to develop an optimized process for fabricating Raman-labeled nanoparticles for a SERS-based immunoassay on a polystyrene substrate. We have developed a method for fabricating SERS nanoparticle probes for use in a light scattering immunoassay on a polystyrene substrate. The light scattering profile of both spherical gold nanoparticle and gold nanorod SERS probes were characterized using Raman spectroscopy and optical absorbance spectroscopy. The effects of substrate interference and autofluorescence were reduced by selecting a Raman reporter with a strong light scattering response in a spectral region where interfering substrate emission peaks are minimized. Both spherical gold nanoparticles and gold nanorods SERS probes used in the immunoassay were detected at labeling concentrations in the low pM range. This analytical sensitivity falls within the typical dynamic range for direct labeling of cell-surface biomarkers using SERS probes. SERS nanoparticle probes were fabricated to produce a strong light scattering signal despite substrate interference. The optical extinction and inelastic light scattering of these probes was detected by optical absorbance spectroscopy and Raman spectroscopy, respectively. This immunoassay demonstrates the feasibility of analyzing strongly enhanced Raman signals on polystyrene, which is an inexpensive yet non-ideal Raman substrate. The assay sensitivity, which is in the low pM range, suggests that these SERS probe particles could be used for Raman labeling of cell or tissue samples in a polystyrene tissue culture plate. With continued development, this approach could be used for direct labeling of multiple cell surface biomarkers on strongly interfering substrate platforms.

Starch-assisted synthesis and optical properties of ZnS nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Xiuying, E-mail: xiuyingt@yahoo.com; Wen, Jin; Wang, Shumei

Highlights: • ZnS spherical nanostructure was prepared via starch-assisted method. • The crystalline lattice structure, morphologies, chemical and optical properties of ZnS nanoparticles. • The forming mechanism of ZnS nanoparticles. • ZnS spherical nano-structure can show blue emission at 460–500 nm. - Abstract: ZnS nanoparticles are fabricated via starch-assisted method. The effects of different starch amounts on structure and properties of samples are investigated, and the forming mechanism of ZnS nanoparticles is discussed. By X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible (UV–vis)more » spectroscopy and fluorescence (FL) spectrometer, their phases, crystalline lattice structure, morphologies, chemical and optical properties are characterized. The results show that ZnS has polycrystalline spherical structure with the mean diameter of 130 nm. Sample without starch reveals irregular aggregates with particle size distribution of 0.5–2 μm. The band gap value of ZnS is 3.97 eV. The chemical interaction exists between starch molecules and ZnS nanoparticles by hydrogen bonds. The stronger FL emission peaks of ZnS synthesized with starch, indicate a larger content of sulfur vacancies or defects than ZnS synthesized without starch.« less

CORONAL PROPERTIES OF THE SEYFERT 1.9 GALAXY MCG-05-23-016 DETERMINED FROM HARD X-RAY SPECTROSCOPY WITH NuSTAR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baloković, M.; Harrison, F. A.; Esmerian, C. J.

2015-02-10

Measurements of the high-energy cut-off in the coronal continuum of active galactic nuclei have long been elusive for all but a small number of the brightest examples. We present a direct measurement of the cut-off energy in the nuclear continuum of the nearby Seyfert 1.9 galaxy MCG-05-23-016 with unprecedented precision. The high sensitivity of NuSTAR up to 79 keV allows us to clearly disentangle the spectral curvature of the primary continuum from that of its reflection component. Using a simple phenomenological model for the hard X-ray spectrum, we constrain the cut-off energy to 116{sub −5}{sup +6} keV with 90% confidence.more » Testing for more complex models and nuisance parameters that could potentially influence the measurement, we find that the cut-off is detected robustly. We further use simple Comptonized plasma models to provide independent constraints for both the kinetic temperature of the electrons in the corona and its optical depth. At the 90% confidence level, we find kT{sub e} = 29 ± 2 keV and τ {sub e} = 1.23 ± 0.08 assuming a slab (disk-like) geometry, and kT{sub e} = 25 ± 2 keV and τ {sub e} = 3.5 ± 0.2 assuming a spherical geometry. Both geometries are found to fit the data equally well and their two principal physical parameters are correlated in both cases. With the optical depth in the τ {sub e} ≳ 1 regime, the data are pushing the currently available theoretical models of the Comptonized plasma to the limits of their validity. Since the spectral features and variability arising from the inner accretion disk have been observed previously in MCG-05-23-016, the inferred high optical depth implies that a spherical or disk-like corona cannot be homogeneous.« less

Subjective depth of field in presence of 4th-order and 6th-order Zernike spherical aberration using adaptive optics technology.

PubMed

Benard, Yohann; Lopez-Gil, Norberto; Legras, Richard

2010-12-01

To study the impact on the subjective depth of field of 4th-order spherical aberration and its combination with 6th-order spherical aberration and analyze the accuracy of image-quality metrics in predicting the impact. Laboratoire Aimé Cotton, Centre National de la Recherche Scientifique, Université Paris-Sud, Orsay, France. Case series. Subjective depth of field was defined as the range of defocus at which the target (3 high-contrast letters at 20/50) was perceived acceptable. Depth of field was measured using 0.18 diopter (D) steps in young subjects with the addition of the following spherical aberration values: ±0.3 μm and ±0.6 μm 4th-order spherical aberration with 3.0 mm and 6.0 mm pupils and ±0.3 μm 4th-order spherical aberration with ±0.1 μm 6th-order spherical aberration for 6.0 mm pupils. The addition of ±0.3 and ±0.6 μm 4th-order spherical aberration increased depth of field by 30% and 45%, respectively. The combination of 4th-order spherical aberration and 6th-order spherical aberration of opposite signs increased depth of field more than 4th-order spherical aberration alone (ie, 63%), while the combination of 4th-order spherical aberration and 6th-order spherical aberration of the same signs did not (ie, 24%). Whereas the midpoint of the depth of field could be predicted by image-quality metrics, none was found a good predictor of objectionable depth of field. Subjective depth of field increased when 4th-order spherical aberration and 6th-order spherical aberration of opposite signs were added but could not be predicted with image-quality metrics. Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

3D optical tomography in the presence of void regions

NASA Astrophysics Data System (ADS)

Riley, J.; Dehghani, Hamid; Schweiger, Martin; Arridge, Simon R.; Ripoll, Jorge; Nieto-Vesperinas, Manuel

2000-12-01

We present an investigation of the effect of a 3D non-scattering gap region on image reconstruction in diffuse optical tomography. The void gap is modelled by the Radiosity-Diffusion method and the inverse problem is solved using the adjoint field method. The case of a sphere with concentric spherical gap is used as an example.

3D optical tomography in the presence of void regions.

PubMed

Riley, J; Dehghani, H; Schweiger, M; Arridge, S; Ripoll, J; Nieto-Vesperinas, M

2000-12-18

We present an investigation of the effect of a 3D non-scattering gap region on image reconstruction in diffuse optical tomography. The void gap is modelled by the Radiosity-Diffusion method and the inverse problem is solved using the adjoint field method. The case of a sphere with concentric spherical gap is used as an example.

The Geometrical Optics PSF with Third Order Aberrations

NASA Astrophysics Data System (ADS)

Díaz-Uribe, Rufino; Campos-García, Manuel

2008-04-01

In this paper the calculation of the GPSF from the Geometrical Optics Irradiance Law (GOIL) is recalled, including some details not found in other references. Also it is explored an alternative solution based on the Irradiance Transport Equation (ITE). Some simulations of images of an extended object produced by an image forming instrument affected by spherical aberration are shown.

Nanoshells as a high-pressure gauge

NASA Astrophysics Data System (ADS)

Tempere, Jacques; van den Broeck, Nick; Putteneers, Katrijn; Silvera, Isaac

2012-02-01

Nanoshells, consisting of multiple spherical layers, have an extensive list of applications, usually performing the function of a probe. We add a new application to this list in the form of a high-pressure gauge in a Diamond Anvil Cell (DAC). In a DAC, where high pressures are reached by pressing two diamonds together, existing gauges fail at higher pressures because of calibration difficulties and obscuring effects in the diamonds. The nanoshell gauge does not face this issue since its optical spectrum can be engineered by altering the thickness of its layers. Furthermore their properties are measured by broad band optical transmission spectroscopy leading to a very large signal-to-noise ratio even in the multi-megabar pressure regime where ruby measurements become challenging. Theoretical calculations based on the Maxwell equations in a spherical geometry combined with the Vinet equation of state show that a three-layer geometry (SiO2-Au-SiO2) indeed has a measurable pressure-dependent optical response desirable for gauges.

Fresnel diffraction by spherical obstacles

NASA Technical Reports Server (NTRS)

Hovenac, Edward A.

1989-01-01

Lommel functions were used to solve the Fresnel-Kirchhoff diffraction integral for the case of a spherical obstacle. Comparisons were made between Fresnel diffraction theory and Mie scattering theory. Fresnel theory is then compared to experimental data. Experiment and theory typically deviated from one another by less than 10 percent. A unique experimental setup using mercury spheres suspended in a viscous fluid significantly reduced optical noise. The major source of error was due to the Gaussian-shaped laser beam.

An intersecting chord method for minimum circumscribed sphere and maximum inscribed sphere evaluations of sphericity error

NASA Astrophysics Data System (ADS)

Liu, Fei; Xu, Guanghua; Zhang, Qing; Liang, Lin; Liu, Dan

2015-11-01

As one of the Geometrical Product Specifications that are widely applied in industrial manufacturing and measurement, sphericity error can synthetically scale a 3D structure and reflects the machining quality of a spherical workpiece. Following increasing demands in the high motion performance of spherical parts, sphericity error is becoming an indispensable component in the evaluation of form error. However, the evaluation of sphericity error is still considered to be a complex mathematical issue, and the related research studies on the development of available models are lacking. In this paper, an intersecting chord method is first proposed to solve the minimum circumscribed sphere and maximum inscribed sphere evaluations of sphericity error. This new modelling method leverages chord relationships to replace the characteristic points, thereby significantly reducing the computational complexity and improving the computational efficiency. Using the intersecting chords to generate a virtual centre, the reference sphere in two concentric spheres is simplified as a space intersecting structure. The position of the virtual centre on the space intersecting structure is determined by characteristic chords, which may reduce the deviation between the virtual centre and the centre of the reference sphere. In addition,two experiments are used to verify the effectiveness of the proposed method with real datasets from the Cartesian coordinates. The results indicate that the estimated errors are in perfect agreement with those of the published methods. Meanwhile, the computational efficiency is improved. For the evaluation of the sphericity error, the use of high performance computing is a remarkable change.

Spectrally controlled interferometry for measurements of flat and spherical optics

NASA Astrophysics Data System (ADS)

Salsbury, Chase; Olszak, Artur G.

2017-10-01

Conventional interferometry is widely used to measure spherical and at surfaces with nanometer level precision but is plagued by back reflections. We describe a new method of isolating the measurement surface by controlling spectral properties of the source (Spectrally Controlled Interferometry - SCI). Using spectral modulation of the interferometer's source enables formation of localized fringes where the optical path difference is non-zero. As a consequence it becomes possible to form white-light like fringes in common path interferometers, such as the Fizeau. The proposed setup does not require mechanical phase shifting, resulting in simpler instruments and the ability to upgrade existing interferometers. Furthermore, it allows absolute measurement of distance, including radius of curvature of lenses in a single setup with possibility of improving the throughput and removing some modes of failure.

About the role of phase matching between a coated microsphere and a tapered fiber: experimental study.

PubMed

Ristić, Davor; Rasoloniaina, Alphonse; Chiappini, Andrea; Féron, Patrice; Pelli, Stefano; Conti, Gualtiero Nunzi; Ivanda, Mile; Righini, Giancarlo C; Cibiel, Gilles; Ferrari, Maurizio

2013-09-09

Coatings of spherical optical microresonators are widely employed for different applications. Here the effect of the thickness of a homogeneous coating layer on the coupling of light from a tapered fiber to a coated microsphere has been studied. Spherical silica microresonators were coated using a 70SiO(2)- 30HfO(2) glass doped with 0.3 mol% Er(3+) ions. The coupling of a 1480 nm pump laser inside the sphere has been assessed using a tapered optical fiber and observing the 1530-1580 nm Er(3+) emission outcoupled to the same tapered fiber. The measurements were done for different coating thicknesses and compared with theoretical calculations to understand the relationship of the detected signal with the whispering gallery mode electric field profiles.

Optical trapping performance of dielectric-metallic patchy particles

PubMed Central

Lawson, Joseph L.; Jenness, Nathan J.; Clark, Robert L.

2015-01-01

We demonstrate a series of simulation experiments examining the optical trapping behavior of composite micro-particles consisting of a small metallic patch on a spherical dielectric bead. A full parameter space of patch shapes, based on current state of the art manufacturing techniques, and optical properties of the metallic film stack is examined. Stable trapping locations and optical trap stiffness of these particles are determined based on the particle design and potential particle design optimizations are discussed. A final test is performed examining the ability to incorporate these composite particles with standard optical trap metrology technologies. PMID:26832054

AERONET-Based Nonspherical Dust Optical Models and Effects on the VIIRS Deep Blue/SOAR Over Water Aerosol Product

NASA Astrophysics Data System (ADS)

Lee, Jaehwa; Hsu, N. Christina; Sayer, Andrew M.; Bettenhausen, Corey; Yang, Ping

2017-10-01

Aerosol Robotic Network (AERONET)-based nonspherical dust optical models are developed and applied to the Satellite Ocean Aerosol Retrieval (SOAR) algorithm as part of the Version 1 Visible Infrared Imaging Radiometer Suite (VIIRS) NASA "Deep Blue" aerosol data product suite. The optical models are created using Version 2 AERONET inversion data at six distinct sites influenced frequently by dust aerosols from different source regions. The same spheroid shape distribution as used in the AERONET inversion algorithm is assumed to account for the nonspherical characteristics of mineral dust, which ensures the consistency between the bulk scattering properties of the developed optical models and the AERONET-retrieved microphysical and optical properties. For the Version 1 SOAR aerosol product, the dust optical model representative for Capo Verde site is used, considering the strong influence of Saharan dust over the global ocean in terms of amount and spatial coverage. Comparisons of the VIIRS-retrieved aerosol optical properties against AERONET direct-Sun observations at five island/coastal sites suggest that the use of nonspherical dust optical models significantly improves the retrievals of aerosol optical depth (AOD) and Ångström exponent by mitigating the well-known artifact of scattering angle dependence of the variables, which is observed when incorrectly assuming spherical dust. The resulting removal of these artifacts results in a more natural spatial pattern of AOD along the transport path of Saharan dust to the Atlantic Ocean; that is, AOD decreases with increasing distance transported, whereas the spherical assumption leads to a strong wave pattern due to the spurious scattering angle dependence of AOD.

Computer numerically controlled (CNC) aspheric shaping with toroidal Wheels (Abstract Only)

NASA Astrophysics Data System (ADS)

Ketelsen, D.; Kittrell, W. C.; Kuhn, W. M.; Parks, R. E.; Lamb, George L.; Baker, Lynn

1987-01-01

Contouring with computer numerically controlled (CNC) machines can be accomplished with several different tool geometries and coordinated machine axes. To minimize the number of coordinated axes for nonsymmetric work to three, it is common practice to use a spherically shaped tool such as a ball-end mill. However, to minimize grooving due to the feed and ball radius, it is desirable to use a long ball radius, but there is clearly a practical limit to ball diameter with the spherical tool. We have found that the use of commercially available toroidal wheels permits long effective cutting radii, which in turn improve finish and minimize grooving for a set feed. In addition, toroidal wheels are easier than spherical wheels to center accurately. Cutting parameters are also easier to control because the feed rate past the tool does not change as the slope of the work changes. The drawback to the toroidal wheel is the more complex calculation of the tool path. Of course, once the algorithm is worked out, the tool path is as easily calculated as for a spherical tool. We have performed two experiments with the Large Optical Generator (LOG) that were ideally suited to three-axis contouring--surfaces that have no axis of rotational symmetry. By oscillating the cutting head horizontally or vertically (in addition to the motions required to generate the power of the surface) , and carefully coordinating those motions with table rotation, the mostly astigmatic departure for these surfaces is produced. The first experiment was a pair of reflector molds that together correct the spherical aberration of the Arecibo radio telescope. The larger of these was 5 m in diameter and had a 12 cm departure from the best-fit sphere. The second experiment was the generation of a purely astigmatic surface to demonstrate the feasibility of producing axially symmetric asphe.rics while mounted and rotated about any off-axis point. Measurements of the latter (the first experiment had relatively loose tolerances) indicate an accuracy only 3 or 4 times that achieved by conventional two-axis contouring (10 AM as opposed to 3 pm rms) The successful completion of these projects demonstrates the successful application of three-axis contouring with the LOG. Toroidal cutters have also solved many of the drawbacks of spherical wheels. Work remains to be done in improving machine response and decreasing the contribution of backlash errors.

Exact optics - III. Schwarzschild's spectrograph camera revised

NASA Astrophysics Data System (ADS)

Willstrop, R. V.

2004-03-01

Karl Schwarzschild identified a system of two mirrors, each defined by conic sections, free of third-order spherical aberration, coma and astigmatism, and with a flat focal surface. He considered it impractical, because the field was too restricted. This system was rediscovered as a quadratic approximation to one of Lynden-Bell's `exact optics' designs which have wider fields. Thus the `exact optics' version has a moderate but useful field, with excellent definition, suitable for a spectrograph camera. The mirrors are strongly aspheric in both the Schwarzschild design and the exact optics version.

PHIPS-HALO: the airborne Particle Habit Imaging and Polar Scattering probe - Part 1: Design and operation

NASA Astrophysics Data System (ADS)

Abdelmonem, Ahmed; Järvinen, Emma; Duft, Denis; Hirst, Edwin; Vogt, Steffen; Leisner, Thomas; Schnaiter, Martin

2016-07-01

The number and shape of ice crystals present in mixed-phase and ice clouds influence the radiation properties, precipitation occurrence and lifetime of these clouds. Since clouds play a major role in the climate system, influencing the energy budget by scattering sunlight and absorbing heat radiation from the earth, it is necessary to investigate the optical and microphysical properties of cloud particles particularly in situ. The relationship between the microphysics and the single scattering properties of cloud particles is usually obtained by modelling the optical scattering properties from in situ measurements of ice crystal size distributions. The measured size distribution and the assumed particle shape might be erroneous in case of non-spherical ice particles. There is a demand to obtain both information correspondently and simultaneously for individual cloud particles in their natural environment. For evaluating the average scattering phase function as a function of ice particle habit and crystal complexity, in situ measurements are required. To this end we have developed a novel airborne optical sensor (PHIPS-HALO) to measure the optical properties and the corresponding microphysical parameters of individual cloud particles simultaneously. PHIPS-HALO has been tested in the AIDA cloud simulation chamber and deployed in mountain stations as well as research aircraft (HALO and Polar 6). It is a successive version of the laboratory prototype instrument PHIPS-AIDA. In this paper we present the detailed design of PHIPS-HALO, including the detection mechanism, optical design, mechanical construction and aerodynamic characterization.

Balance of corneal horizontal coma by internal optics in eyes with intraocular artificial lenses: evidence of a passive mechanism.

PubMed

Marcos, Susana; Rosales, Patricia; Llorente, Lourdes; Barbero, Sergio; Jiménez-Alfaro, I

2008-01-01

It is well known that the aberrations of the cornea are partially compensated by the aberrations of the internal optics of the eye (primarily the crystalline lens) in young subjects. This effect has been found not only for the spherical aberration, but also for horizontal coma. It has been debated whether the compensation of horizontal coma is the result of passive mechanism [Artal, P., Benito, A., & Tabernero, J. (2006). The human eye is an example of robust optical design. Journal of Vision, 6 (1), 1-7] or through an active developmental feedback process [Kelly, J. E., Mihashi, T., & Howland, H. C. (2004). Compensation of corneal horizontal/vertical astigmatism, lateral coma, and spherical aberration by internal optics of the eye. Journal of Vision, 4 (4), 262-271]. In this study we investigate the active or passive nature of the horizontal coma compensation using eyes with artificial lenses, where no active developmental process can be present. We measured total and corneal aberrations, and lens tilt and decentration in a group of 38 eyes implanted with two types of intraocular lenses designed to compensate the corneal spherical aberration of the average population. We found that spherical aberration was compensated by 66%, and horizontal coma by 87% on average. The spherical aberration is not compensated at an individual level, but horizontal coma is compensated individually (coefficients of correlation corneal/internal aberration: -0.946, p<0.0001). The fact that corneal (but not total) horizontal coma is highly correlated with angle lamda (computed from the shift of the 1st Purkinje image from the pupil center, for foveal fixation) indicates that the compensation arises primarily from the geometrical configuration of the eye (which generates horizontal coma of opposite signs in the cornea and internal optics). The amount and direction of tilts and misalignments of the lens are comparable to those found in young eyes, and on average tend to compensate (rather than increase) horizontal coma. Computer simulations using customized model eyes and different designs of intraocular lenses show that, while not all designs produce a compensation of horizontal coma, a wide range of aspheric biconvex designs may produce comparable compensation to that found in young eyes with crystalline lenses, over a relatively large field of view. These findings suggest that the lens shape, gradient index or foveal location do not need to be fine-tuned to achieve a compensation of horizontal coma. Our results cannot exclude a fine-tuning for the orientation of the crystalline lens, since cataract surgery seems to preserve the position of the capsule.

Asymptotic Distribution of the Likelihood Ratio Test Statistic for Sphericity of Complex Multivariate Normal Distribution.

DTIC Science & Technology

1981-08-01

RATIO TEST STATISTIC FOR SPHERICITY OF COMPLEX MULTIVARIATE NORMAL DISTRIBUTION* C. Fang P. R. Krishnaiah B. N. Nagarsenker** August 1981 Technical...and their applications in time sEries, the reader is referred to Krishnaiah (1976). Motivated by the applications in the area of inference on multiple...for practical purposes. Here, we note that Krishnaiah , Lee and Chang (1976) approxi- mated the null distribution of certain power of the likeli

A strategy for recovery: Report of the HST Strategy Panel

NASA Technical Reports Server (NTRS)

Brown, R. A. (Editor); Ford, H. C. (Editor)

1991-01-01

The panel met to identify and assess strategies for recovering the Hubble Space Telescope (HST) capabilities degraded by a spherical aberration. The panels findings and recommendations to correct the problem with HST are given. The optical solution is a pair of mirrors for each science instrument field of view. The Corrective Optics Space Telescope Axial Replacement (COSTAR) is the proposed device to carry and deploy the corrective optics. A 1993 servicing mission is planned.

Wavefront aberrations and retinal image quality in different lenticular opacity types and densities.

PubMed

Wu, Cheng-Zhe; Jin, Hua; Shen, Zhen-Nv; Li, Ying-Jun; Cui, Xun

2017-11-10

To investigate wavefront aberrations in the entire eye and in the internal optics (lens) and retinal image qualities according to different lenticular opacity types and densities. Forty-one eyes with nuclear cataract, 33 eyes with cortical cataract, and 29 eyes with posterior subcapsular cataract were examined. In each group, wavefront aberrations in the entire eye and in the internal optics and retinal image quality were measured using a raytracing aberrometer. Eyes with cortical cataracts showed significantly higher coma-like aberrations compared to the other two groups in both entire eye and internal optic aberrations (P = 0.012 and P = 0.007, respectively). Eyes with nuclear cataract had lower spherical-like aberrations than the other two groups in both entire eye and internal optics aberrations (P < 0.001 and P < 0.001, respectively). In the nuclear cataract group, nuclear lens density was negatively correlated with internal spherical aberrations (r = -0.527, P = 0.005). Wavefront technology is useful for objective and quantitative analysis of retinal image quality deterioration in eyes with different early lenticular opacity types and densities. Understanding the wavefront optical properties of different crystalline lens opacities may help ophthalmic surgeons determine the optimal time to perform cataract surgery.

Seasonal Bias of Retrieved Ice Cloud Optical Properties Based on MISR and MODIS Measurements

NASA Astrophysics Data System (ADS)

Wang, Y.; Hioki, S.; Yang, P.; Di Girolamo, L.; Fu, D.

2017-12-01

The precise estimation of two important cloud optical and microphysical properties, cloud particle optical thickness and cloud particle effective radius, is fundamental in the study of radiative energy budget and hydrological cycle. In retrieving these two properties, an appropriate selection of ice particle surface roughness is important because it substantially affects the single-scattering properties. At present, using a predetermined ice particle shape without spatial and temporal variations is a common practice in satellite-based retrieval. This approach leads to substantial uncertainties in retrievals. The cloud radiances measured by each of the cameras of the Multi-angle Imaging SpectroRadiometer (MISR) instrument are used to estimate spherical albedo values at different scattering angles. By analyzing the directional distribution of estimated spherical albedo values, the degree of ice particle surface roughness is estimated. With an optimal degree of ice particle roughness, cloud optical thickness and effective radius are retrieved based on a bi-spectral shortwave technique in conjunction with two Moderate Resolution Imaging Spectroradiometer (MODIS) bands centered at 0.86 and 2.13 μm. The seasonal biases of retrieved cloud optical and microphysical properties, caused by the uncertainties in ice particle roughness, are investigated by using one year of MISR-MODIS fused data.

Wave front engineering by means of diffractive optical elements for applications in microscopy

NASA Astrophysics Data System (ADS)

Cojoc, Dan; Ferrari, Enrico; Garbin, Valeria; Cabrini, Stefano; Carpentiero, Alessandro; Prasciolu, Mauro; Businaro, Luca; Kaulich, Burchard; Di Fabrizio, Enzo

2006-05-01

We present a unified view regarding the use of diffractive optical elements (DOEs) for microscopy applications a wide range of electromagnetic spectrum. The unified treatment is realized through the design and fabrication of DOE through which wave front beam shaping is obtained. In particular we show applications ranging from micromanipulation using optical tweezers to X-ray differential interference contrast (DIC) microscopy. We report some details on the design and physical implementation of diffractive elements that beside focusing perform also other optical functions: beam splitting, beam intensity and phase redistribution or mode conversion. Laser beam splitting is used for multiple trapping and independent manipulation of spherical micro beads and for direct trapping and manipulation of biological cells with non-spherical shapes. Another application is the Gauss to Laguerre-Gaussian mode conversion, which allows to trap and transfer orbital angular momentum of light to micro particles with high refractive index and to trap and manipulate low index particles. These experiments are performed in an inverted optical microscope coupled with an infrared laser beam and a spatial light modulator for DOEs implementation. High resolution optics, fabricated by means of e-beam lithography, are demonstrated to control the intensity and the phase of the sheared beams in X-ray DIC microscopy. DIC experiments with phase objects reveal a dramatic increase in image contrast compared to bright-field X-ray microscopy.

ODF Maxima Extraction in Spherical Harmonic Representation via Analytical Search Space Reduction

PubMed Central

Aganj, Iman; Lenglet, Christophe; Sapiro, Guillermo

2015-01-01

By revealing complex fiber structure through the orientation distribution function (ODF), q-ball imaging has recently become a popular reconstruction technique in diffusion-weighted MRI. In this paper, we propose an analytical dimension reduction approach to ODF maxima extraction. We show that by expressing the ODF, or any antipodally symmetric spherical function, in the common fourth order real and symmetric spherical harmonic basis, the maxima of the two-dimensional ODF lie on an analytically derived one-dimensional space, from which we can detect the ODF maxima. This method reduces the computational complexity of the maxima detection, without compromising the accuracy. We demonstrate the performance of our technique on both artificial and human brain data. PMID:20879302

Direct Visualization of Barrier Crossing Dynamics in a Driven Optical Matter System.

PubMed

Figliozzi, Patrick; Peterson, Curtis W; Rice, Stuart A; Scherer, Norbert F

2018-04-25

A major impediment to a more complete understanding of barrier crossing and other single-molecule processes is the inability to directly visualize the trajectories and dynamics of atoms and molecules in reactions. Rather, the kinetics are inferred from ensemble measurements or the position of a transducer ( e. g., an AFM cantilever) as a surrogate variable. Direct visualization is highly desirable. Here, we achieve the direct measurement of barrier crossing trajectories by using optical microscopy to observe position and orientation changes of pairs of Ag nanoparticles, i. e. passing events, in an optical ring trap. A two-step mechanism similar to a bimolecular exchange reaction or the Michaelis-Menten scheme is revealed by analysis that combines detailed knowledge of each trajectory, a statistically significant number of repetitions of the passing events, and the driving force dependence of the process. We find that while the total event rate increases with driving force, this increase is due to an increase in the rate of encounters. There is no drive force dependence on the rate of barrier crossing because the key motion for the process involves a random (thermal) radial fluctuation of one particle allowing the other to pass. This simple experiment can readily be extended to study more complex barrier crossing processes by replacing the spherical metal nanoparticles with anisotropic ones or by creating more intricate optical trapping potentials.

Mirror-based broadband scanner with minimized aberration

NASA Astrophysics Data System (ADS)

Yu, Jiun-Yann; Tzeng, Yu-Yi; Huang, Chen-Han; Chui, Hsiang-Chen; Chu, Shi-Wei

2009-02-01

To obtain specific biochemical information in optical scanning microscopy, labeling technique is routinely required. Instead of the complex and invasive sample preparation procedures, incorporating spectral acquisition, which commonly requires a broadband light source, provides another mechanism to enhance molecular contrast. But most current optical scanning system is lens-based and thus the spectral bandwidth is limited to several hundred nanometers due to anti-reflection coating and chromatic aberration. The spectral range of interest in biological research covers ultraviolet to infrared. For example, the absorption peak of water falls around 3 μm, while most proteins exhibit absorption in the UV-visible regime. For imaging purpose, the transmission window of skin and cerebral tissues fall around 1300 and 1800 nm, respectively. Therefore, to extend the spectral bandwidth of an optical scanning system from visible to mid-infrared, we propose a system composed of metallic coated mirrors. A common issue in such a mirror-based system is aberrations induced by oblique incidence. We propose to compensate astigmatism by exchanging the sagittal and tangential planes of the converging spherical mirrors in the scanning system. With the aid of an optical design software, we build a diffraction-limited broadband scanning system with wavefront flatness better than λ/4 at focal plane. Combined with a mirror-based objective this microscopic system will exhibit full spectral capability and will be useful in microscopic imaging and therapeutic applications.

Impact of spherical nanoparticles on nematic order parameters

NASA Astrophysics Data System (ADS)

Kyrou, C.; Kralj, S.; Panagopoulou, M.; Raptis, Y.; Nounesis, G.; Lelidis, I.

2018-04-01

We study experimentally the impact of spherical nanoparticles on the orientational order parameters of a host nematic liquid crystal. We use spherical core-shell quantum dots that are surface functionalized to promote homeotropic anchoring on their interface with the liquid crystal host. We show experimentally that the orientational order may be strongly affected by the presence of spherical nanoparticles even at low concentrations. The orientational order of the composite system is probed by means of polarized micro-Raman spectroscopy and by optical birefringence measurements as function of temperature and concentration. Our data show that the orientational order depends on the concentration in a nonlinear way, and the existence of a crossover concentration χc≈0.004 pw . It separates two different regimes exhibiting pure-liquid crystal like (χ <χc ) and distorted-nematic ordering (χ >χc ), respectively. In the latter phase the degree of ordering is lower with respect to the pure-liquid crystal nematic phase.

New machining method of high precision infrared window part

NASA Astrophysics Data System (ADS)

Yang, Haicheng; Su, Ying; Xu, Zengqi; Guo, Rui; Li, Wenting; Zhang, Feng; Liu, Xuanmin

2016-10-01

Most of the spherical shell of the photoelectric multifunctional instrument was designed as multi optical channel mode to adapt to the different band of the sensor, there were mainly TV, laser and infrared channels. Without affecting the optical diameter, wind resistance and pneumatic performance of the optical system, the overall layout of the spherical shell was optimized to save space and reduce weight. Most of the shape of the optical windows were special-shaped, each optical window directly participated in the high resolution imaging of the corresponding sensor system, and the optical axis parallelism of each sensor needed to meet the accuracy requirement of 0.05mrad.Therefore precision machining of optical window parts quality will directly affect the photoelectric system's pointing accuracy and interchangeability. Processing and testing of the TV and laser window had been very mature, while because of the special nature of the material, transparent and high refractive rate, infrared window parts had the problems of imaging quality and the control of the minimum focal length and second level parallel in the processing. Based on years of practical experience, this paper was focused on how to control the shape and parallel difference precision of infrared window parts in the processing. Single pass rate was increased from 40% to more than 95%, the processing efficiency was significantly enhanced, an effective solution to the bottleneck problem in the actual processing, which effectively solve the bottlenecks in research and production.

Microwave Polarized Signatures Generated within Cloud Systems: SSM/I Observations Interpreted with Radiative Transfer Simulations

NASA Technical Reports Server (NTRS)

Prigent, Catherine; Pardo, Juan R.; Mishchenko, Michael I.; Rossow, Willaim B.; Hansen, James E. (Technical Monitor)

2001-01-01

Special Sensor Microwave /Imager (SSM/I) observations in cloud systems are studied over the tropics. Over optically thick cloud systems, presence of polarized signatures at 37 and 85 GHz is evidenced and analyzed with the help of cloud top temperature and optical thickness extracted from visible and IR satellite observations. Scattering signatures at 85 GHz (TbV(85) less than or = 250 K) are associated with polarization differences greater than or = 6 K, approx. 50%, of the time over ocean and approx. 40% over land. In addition. over thick clouds the polarization difference at 37 GHz is rarely negligible. The polarization differences at 37 and 85 GHz do not stem from the surface but are generated in regions of relatively homogeneous clouds having high liquid water content. To interpret the observations, a radiative transfer model that includes the scattering by non-spherical particles is developed. based on the T-matrix approach and using the doubling and adding method. In addition to handling randomly and perfectly oriented particles, this model can also simulate the effect of partial orientation of the hydrometeors. Microwave brightness temperatures are simulated at SSM/I frequencies and are compared with the observations. Polarization differences of approx. 2 K can be simulated at 37 GHz over a rain layer, even using spherical drops. The polarization difference is larger for oriented non-spherical particles. The 85 GHz simulations are very sensitive to the ice phase of the cloud. Simulations with spherical particles or with randomly oriented non-spherical ice particles cannot replicate the observed polarization differences. However, with partially oriented non-spherical particles, the observed polarized signatures at 85 GHz are explained, and the sensitivity of the scattering characteristics to the particle size, asphericity, and orientation is analyzed. Implications on rain and ice retrievals are discussed.

Paraboloid-aspheric lenses free of spherical aberration

NASA Astrophysics Data System (ADS)

Lozano-Rincón, Ninfa del C.; Valencia-Estrada, Juan Camilo

2017-07-01

A method to design singlet paraboloid-aspheric lenses free of all orders of spherical aberration with maximum aperture is described. This work includes all parametric formulas to describe paraboloid-aspheric or aspheric-paraboloid lenses for any finite conjugated planes. It also includes the Schwarzchilds approximations (which can be used to calculate one rigorous propagation of light waves in physic optics) to design convex paraboloid-aspheric lenses for imaging an object at infinity, with explicit formulas to calculate thicknesses easily. The results were verified with software through ray tracing.

High spectral resolution lidar using spherical Fabry-Perot to measure aerosol and atmospheric molecular density

NASA Astrophysics Data System (ADS)

Yann, Caraty; Alain, Hauchecorne; Philippe, Keckhut; Jean-François, Mariscal; Eric, Dalmeida

2018-04-01

In theory, the HSRL method should expand the validity range of the atmospheric molecular density and temperature profiles of the Rayleigh LIDAR in the UTLS below 30 km, with an accuracy of 1 K, while suppressing the particle contribution. We tested a Spherical Fabry-Perot which achieves these performances while keeping a big flexibility in optical alignment. However, this device has some limitations (thermal drift and a possible partial depolarisation of the backscattered signal).

Solid colloidal optical wavelength filter

DOEpatents

Alvarez, Joseph L.

1992-01-01

A solid colloidal optical wavelength filter includes a suspension of spheal particles dispersed in a coagulable medium such as a setting plastic. The filter is formed by suspending spherical particles in a coagulable medium; agitating the particles and coagulable medium to produce an emulsion of particles suspended in the coagulable medium; and allowing the coagulable medium and suspended emulsion of particles to cool.

Technology Applications Report 1993

DTIC Science & Technology

1994-01-01

Companies Find Riches in Acousto-Optics 39 BMD Research Spurs Growth of Optics Start-Up 40 Improved Mirror Shaping Techniques to Correct Hubble...without destroying spectral bands along the horizon- tal axis. By developing toroidal mirrors that correct the vertical image, Chromex, Inc. was...which provide better image resolution and wider field-of-view than standard spherical-shaped mirrors , but are more difficult to make. PACE can

Optical Synchrotron Precursors of Radio Hypernovae

NASA Astrophysics Data System (ADS)

Nakauchi, Daisuke; Kashiyama, Kazumi; Nagakura, Hiroki; Suwa, Yudai; Nakamura, Takashi

2015-06-01

We examine the bright radio synchrotron counterparts of low-luminosity gamma-ray bursts and relativistic supernovae (SNe) and find that they can be powered by spherical hypernova (HN) explosions. Our results imply that radio-bright HNe are driven by relativistic jets that are choked deep inside the progenitor stars or quasi-spherical magnetized winds from fast-rotating magnetars. We also consider the optical synchrotron counterparts of radio-bright HNe and show that they can be observed as precursors several days before the SN peak with an r-band absolute magnitude of {{M}r}∼ -14 mag. While previous studies suggested that additional trans-relativistic components are required to power the bright radio emission, we find that they overestimated the energy budget of the trans-relativistic component by overlooking some factors related to the minimum energy of non-thermal electrons. If an additional trans-relativistic component exists, then a much brighter optical precursor with {{M}r}∼ -20 mag can be expected. Thus, the scenarios of radio-bright HNe can be distinguished by using optical precursors, which can be detectable from ≲ 100 Mpc by current SN surveys like the Kiso SN Survey, Palomar Transient Factory, and Panoramic Survey Telescope & Rapid Response System.

Retrieving the Vertical Structure of the Effective Aerosol Complex Index of Refraction from a Combination of Aerosol in Situ and Remote Sensing Measurements During TARFOX

NASA Technical Reports Server (NTRS)

Redemann, J.; Turco, R. P.; Liou, K. N.; Russell, P. B.; Bergstrom, R. W.; Schmid, B.; Livingston, J. M.; Hobbs, P. V.; Hartley, W. S.; Ismail, S.

2000-01-01

The largest uncertainty in estimates of the effects of atmospheric aerosols on climate stems from uncertainties in the determination of their microphysical properties, including the aerosol complex index of refraction, which in turn determines their optical properties. A novel technique is used to estimate the aerosol complex index of refraction in distinct vertical layers from a combination of aerosol in situ size distribution and remote sensing measurements during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX). In particular, aerosol backscatter measurements using the NASA Langley LASE (Lidar Atmospheric Sensing Experiment) instrument and in situ aerosol size distribution data are utilized to derive vertical profiles of the 'effective' aerosol complex index of refraction at 815 nm (i.e., the refractive index that would provide the same backscatter signal in a forward calculation on the basis of the measured in situ particle size distributions for homogeneous, spherical aerosols). A sensitivity study shows that this method yields small errors in the retrieved aerosol refractive indices, provided the errors in the lidar derived aerosol backscatter are less than 30% and random in nature. Absolute errors in the estimated aerosol refractive indices are generally less than 0.04 for the real part and can be as much as 0.042 for the imaginary part in the case of a 30% error in the lidar-derived aerosol backscatter. The measurements of aerosol optical depth from the NASA Ames Airborne Tracking Sunphotometer (AATS-6) are successfully incorporated into the new technique and help constrain the retrieved aerosol refractive indices. An application of the technique to two TARFOX case studies yields the occurrence of vertical layers of distinct aerosol refractive indices. Values of the estimated complex aerosol refractive index range from 1.33 to 1.45 for the real part and 0.001 to 0.008 for the imaginary part. The methodology devised in this study provides, for the first time a complete set of vertically resolved aerosol size distribution and refractive index data, yielding the vertical distribution of aerosol optical properties required for the determination of aersol-induced radiative flux changes

Retrieving the Vertical Structure of the Effective Aerosol Complex Index of Refraction from a Combination of Aerosol in Situ and Remote Sensing Measurements During TARFOX

NASA Technical Reports Server (NTRS)

Redemann, J.; Turco, R. P.; Liou, K. N.; Russell, P. B.; Bergstrom, R. W.; Schmid, B.; Livingston, J. M.; Hobbs, P. V.; Hartley, W. S.; Ismail, S.;

A hyper-spherical adaptive sparse-grid method for high-dimensional discontinuity detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Guannan; Webster, Clayton G.; Gunzburger, Max D.

This work proposes and analyzes a hyper-spherical adaptive hierarchical sparse-grid method for detecting jump discontinuities of functions in high-dimensional spaces is proposed. The method is motivated by the theoretical and computational inefficiencies of well-known adaptive sparse-grid methods for discontinuity detection. Our novel approach constructs a function representation of the discontinuity hyper-surface of an N-dimensional dis- continuous quantity of interest, by virtue of a hyper-spherical transformation. Then, a sparse-grid approximation of the transformed function is built in the hyper-spherical coordinate system, whose value at each point is estimated by solving a one-dimensional discontinuity detection problem. Due to the smoothness of themore » hyper-surface, the new technique can identify jump discontinuities with significantly reduced computational cost, compared to existing methods. Moreover, hierarchical acceleration techniques are also incorporated to further reduce the overall complexity. Rigorous error estimates and complexity analyses of the new method are provided as are several numerical examples that illustrate the effectiveness of the approach.« less

Discontinuous Galerkin finite element methods for radiative transfer in spherical symmetry

NASA Astrophysics Data System (ADS)

Kitzmann, D.; Bolte, J.; Patzer, A. B. C.

2016-11-01

The discontinuous Galerkin finite element method (DG-FEM) is successfully applied to treat a broad variety of transport problems numerically. In this work, we use the full capacity of the DG-FEM to solve the radiative transfer equation in spherical symmetry. We present a discontinuous Galerkin method to directly solve the spherically symmetric radiative transfer equation as a two-dimensional problem. The transport equation in spherical atmospheres is more complicated than in the plane-parallel case owing to the appearance of an additional derivative with respect to the polar angle. The DG-FEM formalism allows for the exact integration of arbitrarily complex scattering phase functions, independent of the angular mesh resolution. We show that the discontinuous Galerkin method is able to describe accurately the radiative transfer in extended atmospheres and to capture discontinuities or complex scattering behaviour which might be present in the solution of certain radiative transfer tasks and can, therefore, cause severe numerical problems for other radiative transfer solution methods.

Spherical self-organizing map using efficient indexed geodesic data structure.

PubMed

Wu, Yingxin; Takatsuka, Masahiro

2006-01-01

The two-dimensional (2D) Self-Organizing Map (SOM) has a well-known "border effect". Several spherical SOMs which use lattices of the tessellated icosahedron have been proposed to solve this problem. However, existing data structures for such SOMs are either not space efficient or are time consuming when searching the neighborhood. We introduce a 2D rectangular grid data structure to store the icosahedron-based geodesic dome. Vertices relationships are maintained by their positions in the data structure rather than by immediate neighbor pointers or an adjacency list. Increasing the number of neurons can be done efficiently because the overhead caused by pointer updates is reduced. Experiments show that the spherical SOM using our data structure, called a GeoSOM, runs with comparable speed to the conventional 2D SOM. The GeoSOM also reduces data distortion due to removal of the boundaries. Furthermore, we developed an interface to project the GeoSOM onto the 2D plane using a cartographic approach, which gives users a global view of the spherical data map. Users can change the center of the 2D data map interactively. In the end, we compare the GeoSOM to the other spherical SOMs by space complexity and time complexity.

Aberration-free intraocular lenses - What does this really mean?

PubMed

Langenbucher, Achim; Schröder, Simon; Cayless, Alan; Eppig, Timo

2017-09-01

So-called aberration-free intraocular lenses (IOLs) are well established in modern cataract surgery. Usually, they are designed to perfectly refract a collimated light beam onto the focal point. We show how much aberration can be expected with such an IOL in a convergent light beam such as that found anterior to the human cornea. Additionally, the aberration in a collimated beam is estimated for an IOL that has no aberrations in the convergent beam. The convergent beam is modelled as the pencil of rays corresponding to the spherical wavefront resulting from a typical corneal power of 43m -1 . The IOLs are modelled as infinitely thin phase plates with 20m -1 optical power placed 5mm behind the cornea. Their aberrations are reported in terms of optical path length difference and longitudinal spherical aberration (LSA) of the marginal rays, as well as nominal spherical aberration (SA) calculated based on a Zernike representation of the wavefront-error at the corneal plane within a 6mm aperture. The IOL designed to have no aberrations in a collimated light beam has an optical path length difference of -1.8μm, and LSA of 0.15m -1 in the convergent beam of a typical eye. The corresponding nominal SA is 0.065μm. The IOL designed to have no aberrations in a convergent light beam has an optical path length difference of 1.8μm, and LSA of -0.15m -1 in the collimated beam. An IOL designed to have no aberrations in a collimated light beam will increase the SA of a patient's eye after implantation. Copyright © 2017. Published by Elsevier GmbH.

A Practical Guide to Experimental Geometrical Optics

NASA Astrophysics Data System (ADS)

Garbovskiy, Yuriy A.; Glushchenko, Anatoliy V.

2017-12-01

Preface; 1. Markets of optical materials, components, accessories, light sources and detectors; 2. Introduction to optical experiments: light producing, light managing, light detection and measuring; 3. Light detectors based on semiconductors: photoresistors, photodiodes in a photo-galvanic regime. Principles of operation and measurements; 4. Linear light detectors based on photodiodes; 5. Basic laws of geometrical optics: experimental verification; 6. Converging and diverging thin lenses; 7. Thick lenses; 8. Lens systems; 9. Simple optical instruments I: the eye and the magnifier, eyepieces and telescopes; 10. Simple optical instruments II: light illuminators and microscope; 11. Spherical mirrors; 12. Introduction to optical aberrations; 13. Elements of optical radiometry; 14. Cylindrical lenses and vials; 15. Methods of geometrical optics to measure refractive index; 16. Dispersion of light and prism spectroscope; 17. Elements of computer aided optical design; Index.

Optimal resolution in Fresnel incoherent correlation holographic fluorescence microscopy

PubMed Central

Brooker, Gary; Siegel, Nisan; Wang, Victor; Rosen, Joseph

2011-01-01

Fresnel Incoherent Correlation Holography (FINCH) enables holograms and 3D images to be created from incoherent light with just a camera and spatial light modulator (SLM). We previously described its application to microscopic incoherent fluorescence wherein one complex hologram contains all the 3D information in the microscope field, obviating the need for scanning or serial sectioning. We now report experiments which have led to the optimal optical, electro-optic, and computational conditions necessary to produce holograms which yield high quality 3D images from fluorescent microscopic specimens. An important improvement from our previous FINCH configurations capitalizes on the polarization sensitivity of the SLM so that the same SLM pixels which create the spherical wave simulating the microscope tube lens, also pass the plane waves from the infinity corrected microscope objective, so that interference between the two wave types at the camera creates a hologram. This advance dramatically improves the resolution of the FINCH system. Results from imaging a fluorescent USAF pattern and a pollen grain slide reveal resolution which approaches the Rayleigh limit by this simple method for 3D fluorescent microscopic imaging. PMID:21445140

Comparisons between geometrical optics and Lorenz-Mie theory

NASA Technical Reports Server (NTRS)

Ungut, A.; Grehan, G.; Gouesbet, G.

1981-01-01

Both the Lorenz-Mie and geometrical optics theories are used in calculating the scattered light patterns produced by transparent spherical particles over a wide range of diameters, between 1.0 and 100 microns, and for the range of forward scattering angles from zero to 20 deg. A detailed comparison of the results shows the greater accuracy of the geometrical optics theory in the forward direction. Emphasis is given to the simultaneous sizing and velocimetry of particles by means of pedestal calibration methods.

Spherical gradient-index lenses as perfect imaging and maximum power transfer devices.

PubMed

Gordon, J M

2000-08-01

Gradient-index lenses can be viewed from the perspectives of both imaging and nonimaging optics, that is, in terms of both image fidelity and achievable flux concentration. The simple class of gradient-index lenses with spherical symmetry, often referred to as modified Luneburg lenses, is revisited. An alternative derivation for established solutions is offered; the method of Fermat's strings and the principle of skewness conservation are invoked. Then these nominally perfect imaging devices are examined from the additional vantage point of power transfer, and the degree to which they realize the thermodynamic limit to flux concentration is determined. Finally, the spherical gradient-index lens of the fish eye is considered as a modified Luneburg lens optimized subject to material constraints.

Determination of pitch rotation in a spherical birefringent microparticle

NASA Astrophysics Data System (ADS)

Roy, Basudev; Ramaiya, Avin; Schäffer, Erik

2018-03-01

Rotational motion of a three dimensional spherical microscopic object can happen either in pitch, yaw or roll fashion. Among these, the yaw motion has been conventionally studied using the intensity of scattered light from birefringent microspheres through crossed polarizers. Up until now, however, there is no way to study the pitch motion in spherical microspheres. Here, we suggest a new method to study the pitch motion of birefringent microspheres under crossed polarizers by measuring the 2-fold asymmetry in the scattered signal either using video microscopy or with optical tweezers. We show a couple of simple examples of pitch rotation determination using video microscopy for a microsphere attached with a kinesin molecule while moving along a microtubule and of a particle diffusing freely in water.

Distortion of ultrashort pulses caused by aberrations

NASA Astrophysics Data System (ADS)

Horváth, Z. L.; Kovács, A. P.; Bor, Zs.

The effect of the primary wave aberrations (spherical aberration, astigmatism and coma) on ultrashort pulses is studied by the Nijboer-Zernike theory. The results of the geometrical and the wave optical treatments are compared.

Controllable Planar Optical Focusing System

NASA Technical Reports Server (NTRS)

Arbabi, Amir (Inventor); Faraon, Andrei (Inventor)

2016-01-01

An optical device has a first metasurface disposed over a substrate. A high-contrast pattern of the first metasurface is operable for modifying, over a first phase profile, a phase front of an incident light beam. A second metasurface, is disposed over a plane parallel to the first metasurface with a second high-contrast pattern and operable for shaping, over a second phase profile, the modified phase front of the incident light beam into a converging spherical phase front. A spacer layer, in which the modified phase front of the incident light beam diffracts, is disposed in a controllably changeable separation between the first and second metasurfaces. Controllably changing the separation between the first and the second metasurfaces by a first distance correspondingly changes the position of the focus point of the converging spherical phase front by a second distance significantly greater than the first distance.

Coherent and incoherent combination of Gaussian beams employing lens array distributed on the spherical chamber.

PubMed

Huang, Zhihua; Wei, Xiaofeng; Li, Mingzhong; Wang, Jianjun; Lin, Honghuan; Xu, Dangpeng; Deng, Ying; Zhang, Rui

2012-04-01

Coherent and incoherent combination of Gaussian beams employing a lens array distributed on the spherical chamber is theoretically analyzed. The output field of each source in the array is coupled through an individual optical system whose local optical axis coincides with the radial direction of the chamber. The resulting intensity profile near the origin is derived. The intensity profile and power in the bucket on the target for rectangular and hexagonal arrangement are numerically calculated. The influences of the center-to-center separation and the ring number of the focusing lens array are given. The synthetic intensity profile of incoherent combination changes little for a lens array scale much smaller than the chamber size. In contrast, the synthetic intensity profile of coherent combination shows an interference pattern with a sharp central peak and sidelobes.

Power Profiles of Commercial Multifocal Soft Contact Lenses.

PubMed

Kim, Eon; Bakaraju, Ravi C; Ehrmann, Klaus

2017-02-01

To evaluate the optical power profiles of commercially available soft multifocal contact lenses and compare their optical designs. The power profiles of 38 types of multifocal contact lenses-three lenses each-were measured in powers +6D, +3D, +1D, -1D, -3D, and -6D using NIMO TR1504 (Lambda-X, Belgium). All lenses were measured in phosphate buffered saline across 8 mm optic zone diameter. Refractive index of each lens material was measured using CLR 12-70 (Index Instruments, UK), which was used for converting measured power in the medium to in-air radial power profiles. Three basic types of power profiles were identified: center-near, center-distance, and concentric-zone ring-type designs. For most of the lens types, the relative plus with respect to prescription power was lower than the corresponding spectacle add. For some lens types, the measured power profiles were shifted by up to 1D across the power range relative to their labeled power. Most of the lenses were designed with noticeable amounts of spherical aberration. The sign and magnitude of spherical aberration can either be power dependent or consistent across the power range. Power profiles can vary widely between the different lens types; however, certain similarities were also observed between some of the center-near designs. For the more recently released lens types, there seems to be a trend emerging to reduce the relative plus with respect to prescription power, include negative spherical aberration, and keep the power profiles consistent across the power range.

Synergy of adaptive thresholds and multiple transmitters in free-space optical communication.

PubMed

Louthain, James A; Schmidt, Jason D

2010-04-26

Laser propagation through extended turbulence causes severe beam spread and scintillation. Airborne laser communication systems require special considerations in size, complexity, power, and weight. Rather than using bulky, costly, adaptive optics systems, we reduce the variability of the received signal by integrating a two-transmitter system with an adaptive threshold receiver to average out the deleterious effects of turbulence. In contrast to adaptive optics approaches, systems employing multiple transmitters and adaptive thresholds exhibit performance improvements that are unaffected by turbulence strength. Simulations of this system with on-off-keying (OOK) showed that reducing the scintillation variations with multiple transmitters improves the performance of low-frequency adaptive threshold estimators by 1-3 dB. The combination of multiple transmitters and adaptive thresholding provided at least a 10 dB gain over implementing only transmitter pointing and receiver tilt correction for all three high-Rytov number scenarios. The scenario with a spherical-wave Rytov number R=0.20 enjoyed a 13 dB reduction in the required SNR for BER's between 10(-5) to 10(-3), consistent with the code gain metric. All five scenarios between 0.06 and 0.20 Rytov number improved to within 3 dB of the SNR of the lowest Rytov number scenario.

Ultrasonic Spray Pyrolysis Deposited Copper Sulphide Thin Films for Solar Cell Applications

PubMed Central

Firat, Y. E.; Yildirim, H.; Erturk, K.

2017-01-01

Polycrystalline copper sulphide (CuxS) thin films were grown by ultrasonic spray pyrolysis method using aqueous solutions of copper chloride and thiourea without any complexing agent at various substrate temperatures of 240, 280, and 320°C. The films were characterized for their structural, optical, and electrical properties by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-rays (EDAX), atomic force microscopy (AFM), contact angle (CA), optical absorption, and current-voltage (I-V) measurements. The XRD analysis showed that the films had single or mixed phase polycrystalline nature with a hexagonal covellite and cubic digenite structure. The crystalline phase of the films changed depending on the substrate temperature. The optical band gaps (Eg) of thin films were 2.07 eV (CuS), 2.50 eV (Cu1.765S), and 2.28 eV (Cu1.765S–Cu2S). AFM results indicated that the films had spherical nanosized particles well adhered to the substrate. Contact angle measurements showed that the thin films had hydrophobic nature. Hall effect measurements of all the deposited CuxS thin films demonstrated them to be of p-type conductivity, and the current-voltage (I-V) dark curves exhibited linear variation. PMID:29109807

Numerical simulation for meniscus shape and optical performance of a MEMS-based liquid micro-lens.

PubMed

Lee, Shong-Leih; Yang, Chao-Fu

2008-11-24

It is very difficult to fabricate tunable optical systems having an aperture below 1000 micrometers with the conventional means on macroscopic scale. Krogmann et al. (J. Opt. A 8, S330-S336, 2006) presented a MEMS-based tunable liquid micro-lens system with an aperture of 300 micrometers. The system exhibited a tuning range of back focal length between 2.3mm and infinity by using the electrowetting effect to change the contact angle of the meniscus shape on silicon with a voltage of 0-45 V. However, spherical aberration was found in their lens system. In the present study, a numerical simulation is performed for this same physical configuration by solving the Young-Laplace equation on the interface of the lens liquid and the surrounding liquid. The resulting meniscus shape produces a back focal length that agrees with the experimental observation excellently. To eliminate the spherical aberration, an electric field is applied on the lens. The electric field alters the Young-Laplace equation and thus changes the meniscus shape and the lens quality. The numerical result shows that the spherical aberration of the lens can be essentially eliminated when a proper electric field is applied.

Direct comparison of extinction coefficients derived from Mie-scattering lidar and number concentrations of particles, subjective weather report in Japan

NASA Astrophysics Data System (ADS)

Shimizu, Atsushi; Sugimoto, Nobuo; Matsui, Ichiro; Nishizawa, Tomoaki

2015-03-01

Two components of the lidar extinction coefficient, the dust extinction and the spherical particles extinction, were obtained from observations made by the National Institute for Environmental Studies lidar network in Japan. These two extinctions were compared with the number concentration of particles measured by an optical particle counter, and with subjective weather reports recorded at the nearest meteorological observatories. The dust extinction corresponded well with the number concentration of large particles with diameters as great as 5 μm and during dry conditions with the number concentration of particles larger than 2 μm. The relationship between the spherical particle extinction and the number of small particles was nearly constant under all conditions. Asian dust was sometimes reported by meteorological observatories in the period of lower dust extinction. This indicates contradicting relationship between human-eye based reports and optical characteristics observed by lidars in some cases. The most consistent results between lidar observation and meteorological reports were obtained in dry mist conditions, in which lidars exhibited higher spherical extinction as expected by the definition of the atmospheric phenomenon of dry mist or haze.

Full-angle tomographic phase microscopy of flowing quasi-spherical cells.

PubMed

Villone, Massimiliano M; Memmolo, Pasquale; Merola, Francesco; Mugnano, Martina; Miccio, Lisa; Maffettone, Pier Luca; Ferraro, Pietro

2017-12-19

We report a reliable full-angle tomographic phase microscopy (FA-TPM) method for flowing quasi-spherical cells along microfluidic channels. This method lies in a completely passive optical system, i.e. mechanical scanning or multi-direction probing of the sample is avoided. It exploits the engineered rolling of cells while they are flowing along a microfluidic channel. Here we demonstrate significant progress with respect to the state of the art of in-flow TPM by showing a general extension to cells having almost spherical shapes while they are flowing in suspension. In fact, the adopted strategy allows the accurate retrieval of rotation angles through a theoretical model of the cells' rotation in a dynamic microfluidic flow by matching it with phase-contrast images resulting from holographic reconstructions. So far, the proposed method is the first and the only one that permits to get in-flow TPM by probing the cells with full-angle, achieving accurate 3D refractive index mapping and the simplest optical setup, simultaneously. Proof of concept experiments were performed successfully on human breast adenocarcinoma MCF-7 cells, opening the way for the full characterization of circulating tumor cells (CTCs) in the new paradigm of liquid biopsy.

Cryogenic Optical Performance of a Light-weight Mirror Assembly for Future Space Astronomical Telescopes: Optical Test Results and Thermal Optical Model

NASA Technical Reports Server (NTRS)

Eng, Ron; Arnold, William; Baker, Markus A.; Bevan, Ryan M.; Carpenter, James R.; Effinger, Michael R.; Gaddy, Darrell E.; Goode, Brian K.; Kegley, Jeffrey R.; Hogue, William D.;

Large-aperture focusing of x rays with micropore optics using dry etching of silicon wafers.

PubMed

Ezoe, Yuichiro; Moriyama, Teppei; Ogawa, Tomohiro; Kakiuchi, Takuya; Mitsuishi, Ikuyuki; Mitsuda, Kazuhisa; Aoki, Tatsuhiko; Morishita, Kohei; Nakajima, Kazuo

2012-03-01

Large-aperture focusing of Al K(α) 1.49 keV x-ray photons using micropore optics made from a dry-etched 4 in. (100 mm) silicon wafer is demonstrated. Sidewalls of the micropores are smoothed with high-temperature annealing to work as x-ray mirrors. The wafer is bent to a spherical shape to collect parallel x rays into a focus. Our result supports that this new type of optics allows for the manufacturing of ultralight-weight and high-performance x-ray imaging optics with large apertures at low cost. © 2012 Optical Society of America

Calculation of the force acting on a micro-sized particle with optical vortex array laser beam tweezers

NASA Astrophysics Data System (ADS)

Kuo, Chun-Fu; Chu, Shu-Chun

2013-03-01

Optical vortices possess several special properties, including carrying optical angular momentum (OAM) and exhibiting zero intensity. Vortex array laser beams have attracts many interests due to its special mesh field distributions, which show great potential in the application of multiple optical traps and dark optical traps. Previously study developed an Ince-Gaussian Mode (IGM)-based vortex array laser beam1. This study develops a simulation model based on the discrete dipole approximation (DDA) method for calculating the resultant force acting on a micro-sized spherical dielectric particle that situated at the beam waist of the IGM-based vortex array laser beams1.

Review of optical freeform surface representation technique and its application

NASA Astrophysics Data System (ADS)

Ye, Jingfei; Chen, Lu; Li, Xinhua; Yuan, Qun; Gao, Zhishan

2017-11-01

Modern advanced manufacturing and testing technologies allow the application of freeform optical elements. Compared with traditional spherical surfaces, an optical freeform surface has more degrees of freedom in optical design and provides substantially improved imaging performance. In freeform optics, the representation technique of a freeform surface has been a fundamental and key research topic in recent years. Moreover, it has a close relationship with other aspects of the design, manufacturing, testing, and application of optical freeform surfaces. Improvements in freeform surface representation techniques will make a significant contribution to the further development of freeform optics. We present a detailed review of the different types of optical freeform surface representation techniques and their applications and discuss their properties and differences. Additionally, we analyze the future trends of optical freeform surface representation techniques.

Reverse depletion effects and the determination of ligand density on some spherical bioparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Chunxiang; Liu, Yanhui, E-mail: ionazati@itp.ac.cn; Fan, Yangtao

In cell environments crowded with macromolecules, the depletion effects act and assist in the assembly of a wide range of cellular structures, from the cytoskeleton to the chromatin loop, which are well accepted. But a recent quantum dot experiment indicated that the dimensions of the receptor–ligand complex have strong effects on the size-dependent exclusion of proteins in cell environments. In this article, a continuum elastic model is constructed to resolve the competition between the dimension of the receptor–ligand complex and depletion effects in the endocytosis of a spherical virus-like bioparticle. Our results show that the depletion effects do not alwaysmore » assist endocytosis of a spherical virus-like bioparticle; while the dimension of the ligand–receptor complex is larger than the size of a small bioparticle in cell environments, the depletion effects do not work and reverse effects appear. The ligand density covered on the virus can be identified quantitatively.« less

A panoramic coded aperture gamma camera for radioactive hotspots localization

NASA Astrophysics Data System (ADS)

Paradiso, V.; Amgarou, K.; Blanc De Lanaute, N.; Schoepff, V.; Amoyal, G.; Mahe, C.; Beltramello, O.; Liénard, E.

2017-11-01

A known disadvantage of the coded aperture imaging approach is its limited field-of-view (FOV), which often results insufficient when analysing complex dismantling scenes such as post-accidental scenarios, where multiple measurements are needed to fully characterize the scene. In order to overcome this limitation, a panoramic coded aperture γ-camera prototype has been developed. The system is based on a 1 mm thick CdTe detector directly bump-bonded to a Timepix readout chip, developed by the Medipix2 collaboration (256 × 256 pixels, 55 μm pitch, 14.08 × 14.08 mm2 sensitive area). A MURA pattern coded aperture is used, allowing for background subtraction without the use of heavy shielding. Such system is then combined with a USB color camera. The output of each measurement is a semi-spherical image covering a FOV of 360 degrees horizontally and 80 degrees vertically, rendered in spherical coordinates (θ,phi). The geometrical shapes of the radiation-emitting objects are preserved by first registering and stitching the optical images captured by the prototype, and applying, subsequently, the same transformations to their corresponding radiation images. Panoramic gamma images generated by using the technique proposed in this paper are described and discussed, along with the main experimental results obtained in laboratories campaigns.

Heterogeneous nucleation on convex spherical substrate surfaces: A rigorous thermodynamic formulation of Fletcher's classical model and the new perspectives derived.

PubMed

Qian, Ma; Ma, Jie

2009-06-07

Fletcher's spherical substrate model [J. Chem. Phys. 29, 572 (1958)] is a basic model for understanding the heterogeneous nucleation phenomena in nature. However, a rigorous thermodynamic formulation of the model has been missing due to the significant complexities involved. This has not only left the classical model deficient but also likely obscured its other important features, which would otherwise have helped to better understand and control heterogeneous nucleation on spherical substrates. This work presents a rigorous thermodynamic formulation of Fletcher's model using a novel analytical approach and discusses the new perspectives derived. In particular, it is shown that the use of an intermediate variable, a selected geometrical angle or pseudocontact angle between the embryo and spherical substrate, revealed extraordinary similarities between the first derivatives of the free energy change with respect to embryo radius for nucleation on spherical and flat substrates. Enlightened by the discovery, it was found that there exists a local maximum in the difference between the equivalent contact angles for nucleation on spherical and flat substrates due to the existence of a local maximum in the difference between the shape factors for nucleation on spherical and flat substrate surfaces. This helps to understand the complexity of the heterogeneous nucleation phenomena in a practical system. Also, it was found that the unfavorable size effect occurs primarily when R<5r( *) (R: radius of substrate and r( *): critical embryo radius) and diminishes rapidly with increasing value of R/r( *) beyond R/r( *)=5. This finding provides a baseline for controlling the size effects in heterogeneous nucleation.

Uncertainties of aerosol retrieval from neglecting non-sphericity of dust aerosols

NASA Astrophysics Data System (ADS)

Li, Chi; Xue, Yong; Yang, Leiku; Guang, Jie

2013-04-01

The Mie theory is conventionally applied to calculate aerosol optical properties in satellite remote sensing applications, while dust aerosols cannot be well modeled by the Mie calculation for their non-sphericity. It has been cited in Mishchenko et al. (1995; 1997) that neglecting non-sphericity can severely influence aerosol optical depth (AOD, ?) retrieval in case of dust aerosols because of large difference of phase functions under spherical and non-spherical assumptions, whereas this uncertainty has not been thoroughly studied. This paper aims at a better understanding of uncertainties on AOD retrieval caused by aerosol non-sphericity. A dust aerosol model with known refractive index and size distribution is generated from long-term AERONET observations since 1999 over China. Then aerosol optical properties, such as the extinction, phase function, single scattering albedo (SSA) are calculated respectively in the assumption of spherical and non-spherical aerosols. Mie calculation is carried out for spherical assumption, meanwhile for non-spherical aerosol modeling, we adopt the pre-calculated scattering kernels and software package presented by Dubovik et al. (2002; 2006), which describes dust as a shape mixture of randomly oriented polydisperse spheroids. Consequently we generate two lookup tables (LUTspheric and LUTspheroid) from simulated satellite received reflectance at top of atmosphere (TOA) under varieties of observing conditions and aerosol loadings using Second Simulation of a Satellite Signal in the Solar Spectrum - Vector (6SV) code. All the simulations are made at 550 nm, and for simplicity the Lambertian surface is assumed. Using the obtained LUTs we examine the differences of TOA reflectance (Δ?TOA = ?spheric - ?spheroid) under different surface reflectance and aerosol loadings. Afterwards AOD is retrieved using LUTspheric from the simulated TOA reflectance by LUTspheroid in order to detect the retrieval errors (Δ? = ?retreived -?input) induced by straightforwardly utilizing Mie theory in dust aerosol retrieval. As expected we find that the uncertainties mainly result from the obvious difference of phase functions (Pspheric and Pspheroid). Errors may be positive or negative, depending on the specific geometry. In scattering angle (θ) regions where Psphericis greater (30°~85° & 145°~180°), we generally get positive Δ?TOA and negative Δ?, and vice versa (85°~145°). For low aerosol loading (? ~0.25) and black surface, |Δ?TOA| could be greater than 0.004 and 0.012 around θ ~120° and θ ~170°, with |Δ?| of ~0.04 and ~0.12 respectively. In most back scattering cases (θ >100°), the magnitude of Δ? is about ten times that of Δ?TOA, while this ratio (|Δ?|/|Δ?TOA|) significantly reduces to as low as ~0.5 for forward scattering, and can reach ~20 at θ ~145°. Moreover, this errors and |Δ?|/|Δ?TOA| can increase more than ten times as aerosol loading gets higher and surface gets brighter. Therefore we conclude that the neglect of non-sphericity introduces substantial errors on radiative transfer simulation and AOD retrieval. As a result of this study, a representative aspheric aerosol model other than Mie calculation is recommended for inversion algorithms related with dust-like non-spherical aerosols. References Dubovik, O., Holben, B. N., Lapyonok, T., Sinyuk, A., Mishchenko, M. I., Yang, P., and Slutsker, I. (2002). Non-spherical aerosol retrieval method employing light scattering by spheroids. Geophyscal Research Letters, 29(10), 1415, doi:10.1029/2001GL014506. Dubovik, O., Sinyuk, A., Lapyonok, T., Holben, B. N., Mishchenko, M., Yang, P., Eck, T. F., Volten, H., Muñoz, O., Veihelmann, B., van der Zande, W. J., Leon, J.-F., Sorokin, M., and Slutsker, I. (2006). Application of spheroid models to account for aerosol particle nonsphericity in remote sensing of desert dust. Journal of Geophysical Research, 111, D11208, doi:10.1029/2005JD006619. Mishchenko, M. I., Lacis, A. A., Carlson, B. E., and Travis, L. D. (1995). Nonsphericity of dust-like aerosols: Implications for aerosol remote sensing and climate modeling, Geophyscal Research Letters, 22, 1077- 1080. Mishchenko, M. I., Travis, L. D., Kahn, R. A., and West, R. A. (1997). Modeling phase functions for dustlike tropospheric aerosols using a shape mixture of randomly oriented polydisperse spheroids, Journal of Geophysical Research, 102, 16831- 16847.

A reflective optical transport system for ultraviolet Thomson scattering from electron plasma waves on OMEGA.

PubMed

Katz, J; Boni, R; Sorce, C; Follett, R; Shoup, M J; Froula, D H

2012-10-01

A reflective optical transport system has been designed for the OMEGA Thomson-scattering diagnostic. A Schwarzschild objective that uses two concentric spherical mirrors coupled to a Pfund objective provides diffraction-limited imaging across all reflected wavelengths. This enables the operator to perform Thomson-scattering measurements of ultraviolet (0.263 μm) light scattered from electron plasma waves.

Design and production of the digital optical module of the KM3NeT project

NASA Astrophysics Data System (ADS)

Leonora, Emanuele; Giordano, Valentina

2017-03-01

The KM3NeT collaboration is building the ARCA and ORCA neutrino telescopes in the depths of the Mediterranean Sea. They will consist of 3-dimensional arrays of photodetectors, called digital optical modules, suspended in the sea by means of vertical string structures, called detection units. The optical modules are composed of a pressure-resistant 17-inch spherical glass vessel, which contains 31 small photomultiplier tubes and all the associated electronics. The multi- photomultiplier solution represents an innovative design with respect to optical modules of all currently operated neutrino telescopes comprising a single large photomultipliers.

The relationship between central corneal thickness and optic disc size in patients with primary open-angle glaucoma in a hospital-based population.

PubMed

Terai, Naim; Spoerl, Eberhard; Pillunat, Lutz E; Kuhlisch, Eberhard; Schmidt, Eckart; Boehm, Andreas G

2011-09-01

To investigate the relationship between central corneal thickness (CCT) and optic disc size in patients with primary open-angle glaucoma (POAG) in a hospital-based population. Data for the right eyes of 1435 White patients with POAG were included in a retrospective hospital-based study. All eyes underwent optic nerve head imaging using Heidelberg Retina Tomograph II (HRT II; Heidelberg Engineering, Heidelberg, Germany) and CCT measurement by ultrasound corneal pachymetry. Eyes with prior intraocular or corneal surgery were excluded. Low-quality HRT II images were also excluded. The impact of age, gender, CCT, intraocular pressure, cylindrical and spherical refractive error as independent factors on optic disc size was investigated in a multiple linear regression analysis. The data for 1104 right eyes qualified for participation in the study. The median age of these patients was 65 years. The median CCT was 547 μm (25th-75th percentile 522-575 μm). The median optic disc size was 2.21 mm(2) (25th-75th percentile 1.89-2.60 mm(2)). Multiple linear regression analysis revealed that age (p = 0.001), CCT (p = 0.001) and spherical equivalent (p = 0.049) were correlated to disc size according to the following formula: disc area = -0.004 × age - 0.001 × CCT - 0.014 × spherical equivalent +3.290. R(2) of the whole model was 0.021. Univariate regression analysis between age and disc area provided R(2) = 0.008 with p = 0.002. Univariate regression analysis between disc area and CCT provided R(2) = 0.005 with p = 0.02. In this retrospective hospital-based study we could not detect a clinically relevant correlation between optic disc size and CCT. The correlation between CCT and disc size and between age and disc size were statistically significant, but the R(2) values were very low. The results of the study are biased because of its hospital-based design, so the results of the study need to be confirmed in a large population-based study. © 2009 The Authors. Journal compilation © 2009 Acta Ophthalmol.

Stable J-aggregation enabled dual photoacoustic and fluorescence nanoparticles for intraoperative cancer imaging

NASA Astrophysics Data System (ADS)

Shakiba, Mojdeh; Ng, Kenneth K.; Huynh, Elizabeth; Chan, Harley; Charron, Danielle M.; Chen, Juan; Muhanna, Nidal; Foster, F. Stuart; Wilson, Brian C.; Zheng, Gang

2016-06-01

J-aggregates display nanoscale optical properties which enable their use in fluorescence and photoacoustic imaging applications. However, control over their optical properties in an in vivo setting is hampered by the conformational lability of the J-aggregate structure in complex biological environments. J-aggregating nanoparticles (JNP) formed by self-assembly of bacteriopheophorbide-lipid (Bchl-lipid) in lipid nanovesicles represents a novel strategy to stabilize J-aggregates for in vivo bioimaging applications. We find that 15 mol% Bchl-lipid embedded within a saturated phospholipid bilayer vesicle was optimal in terms of maximizing Bchl-lipid dye loading, while maintaining a spherical nanoparticle morphology and retaining spectral properties characteristic of J-aggregates. The addition of cholesterol maintains the stability of the J-aggregate absorption band for up to 6 hours in the presence of 90% FBS. In a proof-of-concept experiment, we successfully applied JNPs as a fluorescence contrast agent for real-time intraoperative detection of metastatic lymph nodes in a rabbit head-and-neck cancer model. Lymph node metastasis delineation was further verified by visualizing the JNP within the excised lymph node using photoacoustic imaging. Using JNPs, we demonstrate the possibility of using J-aggregates as fluorescence and photoacoustic contrast agents and may potentially spur the development of other nanomaterials that can stably induce J-aggregation for in vivo cancer bioimaging applications.J-aggregates display nanoscale optical properties which enable their use in fluorescence and photoacoustic imaging applications. However, control over their optical properties in an in vivo setting is hampered by the conformational lability of the J-aggregate structure in complex biological environments. J-aggregating nanoparticles (JNP) formed by self-assembly of bacteriopheophorbide-lipid (Bchl-lipid) in lipid nanovesicles represents a novel strategy to stabilize J-aggregates for in vivo bioimaging applications. We find that 15 mol% Bchl-lipid embedded within a saturated phospholipid bilayer vesicle was optimal in terms of maximizing Bchl-lipid dye loading, while maintaining a spherical nanoparticle morphology and retaining spectral properties characteristic of J-aggregates. The addition of cholesterol maintains the stability of the J-aggregate absorption band for up to 6 hours in the presence of 90% FBS. In a proof-of-concept experiment, we successfully applied JNPs as a fluorescence contrast agent for real-time intraoperative detection of metastatic lymph nodes in a rabbit head-and-neck cancer model. Lymph node metastasis delineation was further verified by visualizing the JNP within the excised lymph node using photoacoustic imaging. Using JNPs, we demonstrate the possibility of using J-aggregates as fluorescence and photoacoustic contrast agents and may potentially spur the development of other nanomaterials that can stably induce J-aggregation for in vivo cancer bioimaging applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/C5NR08165C

Models for randomly distributed nanoscopic domains on spherical vesicles

NASA Astrophysics Data System (ADS)

Anghel, Vinicius N. P.; Bolmatov, Dima; Katsaras, John

2018-06-01

The existence of lipid domains in the plasma membrane of biological systems has proven controversial, primarily due to their nanoscopic size—a length scale difficult to interrogate with most commonly used experimental techniques. Scattering techniques have recently proven capable of studying nanoscopic lipid domains populating spherical vesicles. However, the development of analytical methods able of predicting and analyzing domain pair correlations from such experiments has not kept pace. Here, we developed models for the random distribution of monodisperse, circular nanoscopic domains averaged on the surface of a spherical vesicle. Specifically, the models take into account (i) intradomain correlations corresponding to form factors and interdomain correlations corresponding to pair distribution functions, and (ii) the analytical computation of interdomain correlations for cases of two and three domains on a spherical vesicle. In the case of more than three domains, these correlations are treated either by Monte Carlo simulations or by spherical analogs of the Ornstein-Zernike and Percus-Yevick (PY) equations. Importantly, the spherical analog of the PY equation works best in the case of nanoscopic size domains, a length scale that is mostly inaccessible by experimental approaches such as, for example, fluorescent techniques and optical microscopies. The analytical form factors and structure factors of nanoscopic domains populating a spherical vesicle provide a new and important framework for the quantitative analysis of experimental data from commonly studied phase-separated vesicles used in a wide range of biophysical studies.

[Eyeglasses].

PubMed

Reiner, J

1990-01-01

Spectacles belong to the most ancient inventions in cultural history. Their development, however, cannot be regarded as final. New impetus has resulted in the creation of non-spherical lenses and, through the development of refractive lenses, in a more progressive optic effort.

Multiple Scattering Effects on Pulse Propagation in Optically Turbid Media.

NASA Astrophysics Data System (ADS)

Joelson, Bradley David

The effects of multiple scattering in a optically turbid media is examined for an impulse solution to the radiative transfer equation for a variety of geometries and phase functions. In regions where the complexities of the phase function proved too cumbersome for analytic methods Monte Carlo techniques were developed to describe the entire scalar radiance distribution. The determination of a general spread function is strongly dependent on geometry and particular regions where limits can be placed on the variables of the problem. Hence, the general spread function is first simplified by considering optical regions which reduce the complexity of the variable dependence. First, in the small-angle limit we calculate some contracted spread functions along with their moments and then use Monte Carlo techniques to establish the limitations imposed by the small-angle approximation in planar geometry. The point spread function (PSF) for a spherical geometry is calculated for the full angular spread in the forward direction of ocean waters using Monte Carlo methods in the optically thin and moderate depths and analytic methods in the diffusion domain. The angular dependence of the PSF for various ocean waters is examined for a range of optical parameters. The analytic method used in the diffusion calculation is justified by examining the angular dependence of the radiance of a impulse solution in a planar geometry for a prolongated Henyey-Greenstein phase function of asymmetry factor approximately equal to that of the ocean phase functions. The Legendre moments of the radiance are examined in order to examine the viability of the diffusion approximation which assumes a linearly anisotropic angular distribution for the radiance. A realistic lidar calculation is performed for a variety of ocean waters to determine the effects of multiple scattering on the determination of the speed of sound by using the range gated frequency spectrum of the lidar signal. It is shown that the optical properties of the ocean help to ensure single scatter form for the frequency spectra of the lidar signal. This spectra can then be used to compute the speed of sound and backscatter probability.

Complex coacervation of collagen hydrolysate extracted from leather solid wastes and chitosan for controlled release of lavender oil.

PubMed

Ocak, Buğra

2012-06-15

In the world, approximately 600,000 metric tonnes of chromium-containing solid wastes are generated by the leather industry each year. Environmental concerns and escalating landfill costs are becoming increasingly serious problems to the leather industry and seeking solutions to these problems is a prime concern in much research today. In this study, solid collagen-based protein hydrolysate was isolated from chromium-tanned leather wastes and its chemical properties were determined. Microcapsules of collagen hydrolysate (CH) - chitosan (C) crosslinked with glutaraldehyde (GA) containing Lavender oil (LO) were prepared by complex coacervation method. The effects of various processing parameters, including the CH to C ratio, LO content, and GA, on the oil load (%), oil content (%), encapsulation efficiency (%) and release rate of LO from microcapsules were investigated. As the ratio of C present in the CH/C mixture and crosslinking density increased, the release rate of LO from microcapsules slowed down. Optical and scanning electron microscopy images illustrated that the LO microcapsules were spherical in shape. Fourier transform infrared spectroscopy (FTIR) studies confirmed that there was no significant interaction between CH/C complex and LO. Copyright © 2012 Elsevier Ltd. All rights reserved.

Telephoto axicon

NASA Astrophysics Data System (ADS)

Burvall, Anna; Goncharov, Alexander; Dainty, Chris

2005-09-01

The axicon is an optical element which creates a narrow focal line along the optical axis, unlike the single focal point produced by a lens. The long and precisely defined axicon focal line is used e.g. in alignment, or to extend the depth of focus of existing methods such as optical coherence tomography or light sectioning. Axicons are generally manufactured as refractive cones or diffractive circular gratings. They are also made as lens systems or doublet lenses, which are easier to produce. We present a design in the form of a reflective-refractive single-element device with annular aperture. This very compact system has only two surfaces, which can be spherical or aspheric depending on the quality required of the focal line. Both surfaces have reflective coatings at specific zones, providing an annular beam suitable for generating extended focal lines. One draw-back of a normal axicon is its sensitivity to the angle of illumination. Even for relatively small angles, astigmatism will broaden the focus and give it an asteroid shape. For our design, with spherical surfaces concentric about the center of the entrance pupil, the focal line remains unchanged in off-axis illumination.

The Influence of the Aspheric Profiles for Transition Zone on Optical Performance of Human Eye After Conventional Ablation

NASA Astrophysics Data System (ADS)

Fang, L.

2014-12-01

The analysis in the impact of transition zone on the optical performance of human eye after laser refractive surgery is important for improving visual correction technology. By designing the ablation profiles of aspheric transition zone and creating the ablation profile for conventional refractive surgery in optical zone, the influence of aspheric transition zone on residual aberrations was studied. The results indicated that the ablation profiles of transition zone had a significant influence on the residual wavefront aberrations. For a hyperopia correction, the profile #9 shows a larger induced coma and spherical aberration when the translation of the centre of pupil remains constant. However, for a myopia astigmatism correction, the induced coma and spherical aberration in profile #1 shows relatively larger RMS values than those in other profiles. Therefore, the residual higher order aberrations may be decreased by optimizing ablation profiles of transition zone, but they cannot be eliminated. In order to achieve the best visual performance, the design of ablation pattern of transition zone played a crucial role.

The Gaussian beam mode analysis of classical phase aberrations in diffraction-limited optical systems

NASA Astrophysics Data System (ADS)

Trappe, Neil; Murphy, J. Anthony; Withington, Stafford

2003-07-01

Gaussian beam mode analysis (GBMA) offers a more intuitive physical insight into how light beams evolve as they propagate than the conventional Fresnel diffraction integral approach. In this paper we illustrate that GBMA is a computationally efficient, alternative technique for tracing the evolution of a diffracting coherent beam. In previous papers we demonstrated the straightforward application of GBMA to the computation of the classical diffraction patterns associated with a range of standard apertures. In this paper we show how the GBMA technique can be expanded to investigate the effects of aberrations in the presence of diffraction by introducing the appropriate phase error term into the propagating quasi-optical beam. We compare our technique to the standard diffraction integral calculation for coma, astigmatism and spherical aberration, taking—for comparison—examples from the classic text 'Principles of Optics' by Born and Wolf. We show the advantages of GBMA for allowing the defocusing of an aberrated image to be evaluated quickly, which is particularly important and useful for probing the consequences of astigmatism and spherical aberration.

Influence of image charge effect on impurity-related optical absorption coefficients and refractive index changes in a spherical quantum dot

NASA Astrophysics Data System (ADS)

Vartanian, A. L.; Asatryan, A. L.; Vardanyan, L. A.

2017-03-01

We have investigated the influence of an image charge effect (ICE) on the energies of the ground and first few excited states of a hydrogen-like impurity in a spherical quantum dot (QD) in the presence of an external electric field. The oscillator strengths of transitions from the 1 s -like state to excited states of 2px and 2pz symmetries are calculated as the functions of the strengths of the confinement potential and the electric field. Also, we have studied the effect of image charges on linear and third-order nonlinear optical absorption coefficients and refractive index changes (RICs). The results show that image charges lead to the decrease of energies for all the hydrogen-like states, to the significant enhancement of the oscillator strengths of transitions between the impurity states, and to comparatively large blue shifts in linear, nonlinear, and total absorption coefficients and refractive index changes. Our results indicate that the total optical characteristics can be controlled by the strength of the confinement and the electric field.

Extension of geometrical-optics approximation to on-axis Gaussian beam scattering. II. By a spheroidal particle with end-on incidence.

PubMed

Xu, Feng; Ren, Kuan Fang; Cai, Xiaoshu; Shen, Jianqi

2006-07-10

On the basis of our previous work on the extension of the geometrical-optics approximation to Gaussian beam scattering by a spherical particle, we present a further extension of the method to the scattering of a transparent or absorbing spheroidal particle with the same symmetric axis as the incident beam. As was done for the spherical particle, the phase shifts of the emerging rays due to focal lines, optical path, and total reflection are carefully considered. The angular position of the geometric rainbow of primary order is theoretically predicted. Compared with our results, the Möbius prediction of the rainbow angle has a discrepancy of less than 0.5 degrees for a spheroidal droplet of aspect radio kappa within 0.95 and 1.05 and less than 2 degrees for kappa within 0.89 and 1.11. The flux ratio index F, which qualitatively indicates the effect of a surface wave, is also studied and found to be dependent on the size, refractive index, and surface curvature of the particle.

A dual wavelength imaging system for plasma-surface interaction studies on the National Spherical Torus Experiment Upgrade

DOE PAGES

Scotti, F.; Soukhanovskii, V. A.

2015-12-09

A two-channel spectral imaging system based on a charge injection device radiation-hardened intensified camera was built for studies of plasma-surface interactions on divertor plasma facing components in the National Spherical Torus Experiment Upgrade (NSTX-U) tokamak. By means of commercially available mechanically referenced optical components, the two-wavelength setup images the light from the plasma, relayed by a fiber optic bundle, at two different wavelengths side-by-side on the same detector. Remotely controlled filter wheels are used for narrow band pass and neutral density filters on each optical path allowing for simultaneous imaging of emission at wavelengths differing in brightness up to 3more » orders of magnitude. Applications on NSTX-U will include the measurement of impurity influxes in the lower divertor strike point region and the imaging of plasma-material interaction on the head of the surface analysis probe MAPP (Material Analysis and Particle Probe). Furthermore, the diagnostic setup and initial results from its application on the lithium tokamak experiment are presented.« less

Sub-arcsec X-Ray Telescope for Imaging The Solar Corona In the 0.25 - 1.2 keV Band

NASA Technical Reports Server (NTRS)

Gallagher, Dennis; Cash, Webster; Jelsma, Schuyler; Farmer, Jason

1996-01-01

We have developed an X-ray telescope that uses a new technique for focusing X-rays with grazing incidence optics. The telescope was built with spherical optics for all of its components, utilizing the high quality surfaces obtainable when polishing spherical (as opposed to aspherical) optics. We tested the prototype X-ray telescope in the 300 meter vacuum pipe at White Sands Missile Range, NM. The telescope features 2 degee graze angles with tungsten coatings, yielding a bandpass of 0.25-1.5 keV with a peak effective area of 0.8 sq cm at 0.83 keV. Results from X-ray testing at energies of 0.25 keV and 0.93 keV (C-K and Cu-L) verify 0.5 arcsecond performance at 0.93 keV. Results from modeling the X-ray telescope's response to the Sun show that the current design would be capable of recording 10 half arcsecond images of a solar active region during a 300 second NASA sounding rocket flight.

Numerical investigation on the Ångström exponent of black carbon aerosol

NASA Astrophysics Data System (ADS)

Li, Ji; Liu, Chao; Yin, Yan; Kumar, K. Raghavendra

2016-04-01

Black carbon (BC) plays an important role on the global and regional climate, whereas there are significant uncertainties on its optical properties. Among various optical properties, the Ångström exponent (AE) indicates the spectral variation of the particle-optic interaction and is widely used to understand the aerosol properties. We consider the influence of BC geometry on its optical properties and assess the sensitivity of the AE to particle geometry and size distribution. The fractal aggregates with different fractal dimensions are used to represent realistic BC particles, and popular equivalent volume spherical and spheroidal models are also considered for comparison. Even if the fractal aggregates become highly compact and spherical, their optical properties are still significantly different from those of equivalent volume spheres or spheroids. Meanwhile, the Rayleigh-Debye-Gans approximation can hardly provide accurate results for all optical quantities of aggregates with different dimensions. The extinction Ångström exponent (EAE) and absorption Ångström exponent (AAE) are sensitive to both particle geometry and size distribution. With BC becoming more compact (from fractal aggregate to spheroid and to sphere), the AE becomes more sensitive to particle size distribution. The EAE and AAE of aggregates with different size distributions vary between 1.10-1.63 and 0.87-1.50, respectively, whereas those of the spheres or spheroids have wider ranges. Furthermore, the AE at smaller wavelengths (between 0.35 µm and 0.55 µm) is more sensitive to geometry and size distribution than that given by optical properties at larger wavelengths (between 0.55 µm and 0.88 µm).

Antimicrobial and antitumor activity of platinum and palladium complexes of novel spherical aramides nanoparticles containing flexibilizing linkages: structure-property relationship.

PubMed

Elhusseiny, Amel F; Hassan, Hammed H A M

2013-02-15

Square planar Pd (II) and octahedral Pt (IV) complexes with novel spherical aramides nanoparticles containing flexible linkages ligands have been synthesized and characterized using analytical and spectral techniques. The synthesized complexes have been tested for their antimicrobial activity using Kirby-Bauer disc diffusion method. The antitumor activity has been performed using liver carcinoma (HEPG2), breast carcinoma (MCF7) and colon carcinoma (HCT 116) cell lines. Palladium complexes of polyamides containing sulfones showed the highest potency as antibacterial and antifungal agents. Platinum complexes containing sulfone and ether flexible linkages and chloro groups exhibited high potency as antitumor and antimicrobial agents. The uniform sizes of these nanomaterials could find biological uses such as immune assay and other medical purposes. Copyright © 2012 Elsevier B.V. All rights reserved.

Radiative transfer in spherical shell atmospheres. 2: Asymmetric phase functions

NASA Technical Reports Server (NTRS)

Kattawar, G. W.; Adams, C. N.

1977-01-01

The effects are investigated of sphericity on the radiation reflected from a planet with a homogeneous, conservative scattering atmosphere of optical thicknesses of 0.25 and 1.0. A Henyey-Greenstein phase function with asymmetry factors of 0.5 and 0.7 is considered. Significant differences were found when these results were compared with the plane-parallel calculations. Also large violations of the reciprocity theorem, which is only true for plane-parallel calculations, were noted. Results are presented for the radiance versus height distributions as a function of planetary phase angle.

A Fast and Accurate Method of Radiation Hydrodynamics Calculation in Spherical Symmetry

NASA Astrophysics Data System (ADS)

Stamer, Torsten; Inutsuka, Shu-ichiro

2018-06-01

We develop a new numerical scheme for solving the radiative transfer equation in a spherically symmetric system. This scheme does not rely on any kind of diffusion approximation, and it is accurate for optically thin, thick, and intermediate systems. In the limit of a homogeneously distributed extinction coefficient, our method is very accurate and exceptionally fast. We combine this fast method with a slower but more generally applicable method to describe realistic problems. We perform various test calculations, including a simplified protostellar collapse simulation. We also discuss possible future improvements.

Goos-Hänchen effect on Si thin films with spherical and cylindrical pores

NASA Astrophysics Data System (ADS)

Olaya, Cherrie May; Garcia, Wilson O.; Hermosa, Nathaniel

2018-02-01

We examine the effects on the spatial and angular Goos-Hanchen (GH) beam shifts of spherical and cylindrical pores in a thin film. In our calculations, a p-polarized light is incident on a 1-μm thick porous silicon (Si) thin film on a Si substrate. The beam shifts are within the measurement range of usual optical detectors. Our results show that a technique based on GH shift can be used to determine the porosity and pore structure of thin films at a given thickness.

Baseline Design of a 5-7 kJ KrF Laser Facility for Direct Illumination ICF Experiments.

DTIC Science & Technology

1985-12-31

energies of 5-7 kJ, pulsewidths 5 ns, and broadband (> 20 45) capabilities, the proposed sys - tem is intended primarily for laser-plasma experiments...optics with mounts and align- ment hardware, (3) building, (4) chamber system, (5) oscillator, (6) I.S.I. array, and (7) control sys - tem. Each component...hence, for a spherical mirror, 2 - COA 3pDG (B14) NABE - NOMA 16f2?( Astigmatisnr~ (78)MAx 2CID92 -- (VL8)mlN; hence, for either a spherical mirror or

Machine imparting complex rotary motion for lapping a spherical inner diameter

DOEpatents

Carroll, Thomas A.; Yetter, Harold H.

1986-01-01

An apparatus for imparting complex rotary motion is used to lap an inner spherical diameter surface of a workpiece. A lapping tool consists of a dome and rod mounted along the dome's vertical axis. The workpiece containing the lapping tool is held in a gimbal which uses power derived from a secondary takeoff means to impart rotary motion about a horizontal axis. The gimbal is rotated about a vertical axis by a take means while mounted at a radially outward position on a rotating arm.

Machine imparting complex rotary motion for lapping a spherical inner diameter

DOEpatents

Carroll, T.A.; Yetter, H.H.

1985-01-30

An apparatus for imparting complex rotary motion is used to lap an inner spherical diameter surface of a workpiece. A lapping tool consists of a dome and rod mounted along the dome's vertical axis. The workpiece containing the lapping tool is held in a gimbal which uses power derived from a secondary takeoff means to impart rotary motion about a horizontal axis. The gimbal is rotated about a vertical axis by a take means while mounted at a radially outward position on a rotating arm.

Measurement of quasi-isentropic compressibility of helium and deuterium at pressures of 1500-2000 GPa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mochalov, M. A., E-mail: postmaster@ifv.vniief.ru; Il'kaev, R. I.; Fortov, V. E.

2012-10-15

The quasi-isentropic compressibility of helium and deuterium plasmas at pressures of up to 1500-2000 GPa has been measured using devices with spherical geometry and an X-ray diagnostic complex comprising three betatrons and a multichannel imaging system with electro-optic gamma detectors. A deuterium density of 4.5 g/cm{sup 3} and a helium density of 3.8 g/cm{sup 3} have been obtained at pressures of 2210 and 1580 GPa, respectively. The internal energy of a deuterium plasma at the indicated pressure is about 1 MJ/cm{sup 3}, which is about 100 times greater than the specific energy of condensed chemical explosives. Analysis of the obtainedmore » data shows that the degree of helium ionization under the achieved plasma compression parameters is about 0.9.« less

Heat transfer evaluation in a plasma core reactor

NASA Technical Reports Server (NTRS)

Smith, D. E.; Smith, T. M.; Stoenescu, M. L.

1976-01-01

Numerical evaluations of heat transfer in a fissioning uranium plasma core reactor cavity, operating with seeded hydrogen propellant, was performed. A two-dimensional analysis is based on an assumed flow pattern and cavity wall heat exchange rate. Various iterative schemes were required by the nature of the radiative field and by the solid seed vaporization. Approximate formulations of the radiative heat flux are generally used, due to the complexity of the solution of a rigorously formulated problem. The present work analyzes the sensitivity of the results with respect to approximations of the radiative field, geometry, seed vaporization coefficients and flow pattern. The results present temperature, heat flux, density and optical depth distributions in the reactor cavity, acceptable simplifying assumptions, and iterative schemes. The present calculations, performed in cartesian and spherical coordinates, are applicable to any most general heat transfer problem.

Precise determination of lattice phase shifts and mixing angles

DOE PAGES

Lu, Bing -Nan; Lähde, Timo A.; Lee, Dean; ...

2016-07-09

Here, we introduce a general and accurate method for determining lattice phase shifts and mixing angles, which is applicable to arbitrary, non-cubic lattices. Our method combines angular momentum projection, spherical wall boundaries and an adjustable auxiliary potential. This allows us to construct radial lattice wave functions and to determine phase shifts at arbitrary energies. For coupled partial waves, we use a complex-valued auxiliary potential that breaks time-reversal invariance. We benchmark our method using a system of two spin-1/2 particles interacting through a finite-range potential with a strong tensor component. We are able to extract phase shifts and mixing angles formore » all angular momenta and energies, with precision greater than that of extant methods. We discuss a wide range of applications from nuclear lattice simulations to optical lattice experiments.« less

A Deep Chandra Observation of the Distant Galaxy Cluster MS 1137.5+6625

NASA Astrophysics Data System (ADS)

Grego, Laura; Vrtilek, J. M.; Van Speybroeck, Leon; David, Laurence P.; Forman, William; Carlstrom, John E.; Reese, Erik D.; Joy, Marshall K.

2004-06-01

We present results from a deep Chandra observation of MS 1137.5+66, a distant (z=0.783) and massive cluster of galaxies. Only a few similarly massive clusters are currently known at such high redshifts; accordingly, this observation provides much needed information on the dynamical state of these rare systems. The cluster appears both regular and symmetric in the X-ray image. However, our analysis of the spectral and spatial X-ray data in conjunction with interferometric Sunyaev-Zel'dovich effect data and published deep optical imaging suggests that the cluster has a fairly complex structure. The angular diameter distance we calculate from the Chandra and Sunyaev-Zel'dovich effect data assuming an isothermal, spherically symmetric cluster implies a low value for the Hubble constant for which we explore possible explanations.

High-resolution monochromatic x-ray imaging system based on spherically bent crystals.

PubMed

Aglitskiy, Y; Lehecka, T; Obenschain, S; Bodner, S; Pawley, C; Gerber, K; Sethian, J; Brown, C M; Seely, J; Feldman, U; Holland, G

1998-08-01

We have developed an improved x-ray imaging system based on spherically curved crystals. It is designed and used for diagnostics of targets ablatively accelerated by the Nike KrF laser. A spherically curved quartz crystal (d = .?, R = mm) has been used to produce monochromatic backlit images with the He-like Si resonance line (1865 eV) as the source of radiation. The spatial resolution of the x-ray optical system is 1.7 mum in selected places and 2-3 mum over a larger area. Time-resolved backlit monochromatic images of polystyrene planar targets driven by the Nike facility have been obtained with a spatial resolution of 2.5 mum in selected places and 5 mum over the focal spot of the Nike laser.

Light propagation from fluorescent probes in biological tissues by coupled time-dependent parabolic simplified spherical harmonics equations

PubMed Central

Domínguez, Jorge Bouza; Bérubé-Lauzière, Yves

2011-01-01

We introduce a system of coupled time-dependent parabolic simplified spherical harmonic equations to model the propagation of both excitation and fluorescence light in biological tissues. We resort to a finite element approach to obtain the time-dependent profile of the excitation and the fluorescence light fields in the medium. We present results for cases involving two geometries in three-dimensions: a homogeneous cylinder with an embedded fluorescent inclusion and a realistically-shaped rodent with an embedded inclusion alike an organ filled with a fluorescent probe. For the cylindrical geometry, we show the differences in the time-dependent fluorescence response for a point-like, a spherical, and a spherically Gaussian distributed fluorescent inclusion. From our results, we conclude that the model is able to describe the time-dependent excitation and fluorescent light transfer in small geometries with high absorption coefficients and in nondiffusive domains, as may be found in small animal diffuse optical tomography (DOT) and fluorescence DOT imaging. PMID:21483606

Underwater optical communication performance for laser beam propagation through weak oceanic turbulence.

PubMed

Yi, Xiang; Li, Zan; Liu, Zengji

2015-02-20

In clean ocean water, the performance of a underwater optical communication system is limited mainly by oceanic turbulence, which is defined as the fluctuations in the index of refraction resulting from temperature and salinity fluctuations. In this paper, using the refractive index spectrum of oceanic turbulence under weak turbulence conditions, we carry out, for a horizontally propagating plane wave and spherical wave, analysis of the aperture-averaged scintillation index, the associated probability of fade, mean signal-to-noise ratio, and mean bit error rate. Our theoretical results show that for various values of the rate of dissipation of mean squared temperature and the temperature-salinity balance parameter, the large-aperture receiver leads to a remarkable decrease of scintillation and consequently a significant improvement on the system performance. Such an effect is more noticeable in the plane wave case than in the spherical wave case.

Research on dual-parameter optical fiber sensor based on thin-core fiber and spherical structure

NASA Astrophysics Data System (ADS)

Tong, Zhengrong; Wang, Xue; Zhang, Weihua; Xue, Lifang

2018-04-01

A novel dual-parameter optical fiber sensor is proposed and experimentally demonstrated. The proposed sensor is based on a fiber in-line Mach-Zehnder interferometer, which is fabricated by sandwiching a section of thin-core fiber between two spherical structures made of single-mode fibers. The transmission spectrum exhibits the response of the interference between the core and the different cladding modes. Due to the different wavelength shifts of the two selected dips, the simultaneous measurement of temperature and the surrounding refractive index can be achieved. The measured temperature sensitivities are 0.067 nm/°C and 0.050 nm/°C, and the refractive index sensitivities are  -119.9 nm/RIU and  -69.71 nm/RIU, respectively. In addition, the compact size, simple fabrication and cost-effectiveness of the fiber sensor are also advantages.

A high excitation magnetic quadrupole lens quadruplet incorporating a single octupole lens for a low spherical aberration probe forming lens system

NASA Astrophysics Data System (ADS)

Dou, Yanxin; Jamieson, David N.; Liu, Jianli; Li, Liyi

2018-03-01

This paper describes the design of a new probe forming lens system consisting of a high excitation magnetic quadrupole lens quadruplet that incorporates a single magnetic octupole lens. This system achieves both a high demagnification and a low spherical aberration compared to conventional high excitation systems and is intended for deployment for the Harbin 300 MeV proton microprobe for applications in space science and ion beam therapy. This relative simplicity of the ion optical design to include a single octupole lens minimizes the risks associated with the constructional and operational precision usually needed for the probe forming lens system and this system could also be deployed in microprobe systems that operate with less magnetically rigid ions. The design of the new system is validated with reference to two independent ion optical computer codes.

Derivative matrices of a skew ray for spherical boundary surfaces and their applications in system analysis and design.

PubMed

Lin, Psang Dain

2014-05-10

In a previous paper [Appl. Opt.52, 4151 (2013)], we presented the first- and second-order derivatives of a ray for a flat boundary surface to design prisms. In this paper, that scheme is extended to determine the Jacobian and Hessian matrices of a skew ray as it is reflected/refracted at a spherical boundary surface. The validity of the proposed approach as an analysis and design tool is demonstrated using an axis-symmetrical system for illustration purpose. It is found that these two matrices can provide the search direction used by existing gradient-based schemes to minimize the merit function during the optimization stage of the optical system design process. It is also possible to make the optical system designs more automatic, if the image defects can be extracted from the Jacobian and Hessian matrices of a skew ray.

Tolerance analysis of optical telescopes using coherent addition of wavefront errors

NASA Technical Reports Server (NTRS)

Davenport, J. W.

1982-01-01

A near diffraction-limited telescope requires that tolerance analysis be done on the basis of system wavefront error. One method of analyzing the wavefront error is to represent the wavefront error function in terms of its Zernike polynomial expansion. A Ramsey-Korsch ray trace package, a computer program that simulates the tracing of rays through an optical telescope system, was expanded to include the Zernike polynomial expansion up through the fifth-order spherical term. An option to determine a 3 dimensional plot of the wavefront error function was also included in the Ramsey-Korsch package. Several assimulation runs were analyzed to determine the particular set of coefficients in the Zernike expansion that are effected by various errors such as tilt, decenter and despace. A 3 dimensional plot of each error up through the fifth-order spherical term was also included in the study. Tolerance analysis data are presented.

Compact adaptive optic-optical coherence tomography system

DOEpatents

Olivier, Scot S [Livermore, CA; Chen, Diana C [Fremont, CA; Jones, Steven M [Danville, CA; McNary, Sean M [Stockton, CA

2012-02-28

Badal Optometer and rotating cylinders are inserted in the AO-OCT to correct large spectacle aberrations such as myopia, hyperopic and astigmatism for ease of clinical use and reduction. Spherical mirrors in the sets of the telescope are rotated orthogonally to reduce aberrations and beam displacement caused by the scanners. This produces greatly reduced AO registration errors and improved AO performance to enable high order aberration correction in a patient eyes.

Compact adaptive optic-optical coherence tomography system

DOEpatents

Olivier, Scot S [Livermore, CA; Chen, Diana C [Fremont, CA; Jones, Steven M [Danville, CA; McNary, Sean M [Stockton, CA

2011-05-17

Badal Optometer and rotating cylinders are inserted in the AO-OCT to correct large spectacle aberrations such as myopia, hyperopic and astigmatism for ease of clinical use and reduction. Spherical mirrors in the sets of the telescope are rotated orthogonally to reduce aberrations and beam displacement caused by the scanners. This produces greatly reduced AO registration errors and improved AO performance to enable high order aberration correction in a patient eyes.

Feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas

NASA Technical Reports Server (NTRS)

Stutzman, W. L.; Takamizawa, K.; Werntz, P.; Lapean, J.; Barts, R.

1991-01-01

The following subject areas are covered: General Reflector Antenna Systems Program version 7(GRASP7); Multiple Reflector Analysis Program for Cylindrical Antennas (MRAPCA); Tri-Reflector 2D Synthesis Code (TRTDS); a geometrical optics and a physical optics synthesis techniques; beam scanning reflector, the type 2 and 6 reflectors, spherical reflector, and multiple reflector imaging systems; and radiometric array design.

Development of large aperture telescope technology (LATT): test results on a demonstrator bread-board

NASA Astrophysics Data System (ADS)

Briguglio, R.; Xompero, M.; Riccardi, A.; Lisi, F.; Duò, F.; Vettore, C.; Gallieni, D.; Tintori, M.; Lazzarini, P.; Patauner, C.; Biasi, R.; D'Amato, F.; Pucci, M.; Pereira do Carmo, João.

2017-11-01

The concept of a low areal density primary mirror, actively controlled by actuators, has been investigated through a demonstration prototype. A spherical mirror (400 mm diameter, 2.7 Kg mass) has been manufactured and tested in laboratory and on the optical bench, to verify performance, controllability and optical quality. In the present paper we will describe the prototype and the test results.

Light Scattering by Marine Particles: Modeling with Non-spherical Shapes

DTIC Science & Technology

2009-01-01

1491−1499, 1994. Gordon, H.R. and Tao Du, Light scattering by nonspherical particles: application to coccoliths detached from Emiliania huxleyi...from Emiliania huxleyi, Applied Optics, (2009). van de Hulst, H.C., 1957. Light Scattering by Small Particles, Wiley. Xu, Yu-lin, and Bo A.S...G.C. Boynton, Light scattering by coccoliths detached from Emiliania huxleyi, Applied Optics, (2009). [submitted, in revision] 6 m = 1.05

Light Scattering by Marine Particles: Modeling with Non-spherical Shapes

DTIC Science & Technology

2010-09-30

4271—4282 (1996). Gordon, H.R. and Tao Du, Light scattering by nonspherical particles: application to coccoliths detached from Emiliania huxleyi... Emiliania huxleyi, Applied Optics, (2009). PUBLICATIONS H.R. Gordon, T.J. Smyth, W.M. Balch, and G.C. Boynton, Light scattering by coccoliths...detached from Emiliania huxleyi, Applied Optics, 48, 6059–6073 (2009). [published, refereed] 5 H.R. Gordon, Some Reflections on 35 Years of

Aberration control in adaptive optics: a numerical study of arbitrarily deformable liquid lenses.

PubMed

Lima, N C; Mishra, K; Mugele, F

2017-03-20

By means of numerical simulations, using a computational fluid dynamics software together with an optical ray tracing analysis platform, we show that we can tune various optical aberrations by electrically manipulating the shape of liquid lenses using one hundred individually addressable electrodes. To demonstrate the flexibility of our design, we define electrode patterns based on specific Zernike modes and show that aspherical, cylindrical and decentered shapes of liquid lenses can be produced. Using different voltages, we evaluate the tuning range of spherical aberration (Z11), astigmatism (Z5 and Z6) and coma (Z7), while a hydrostatic pressure is applied to control the average curvature of a microlens with a diameter of 1mm. Upon activating all electrodes simultaneously spherical aberrations of 0.15 waves at a pressure of 30Pa can be suppressed almost completely for the highest voltages applied. For astigmatic and comatic patterns, the values of Z5, Z6 and Z7 increase monotonically with the voltage reaching values up to 0.06, 0.06 and 0.2 waves, respectively. Spot diagrams, wavefront maps and modulation transfer function are reported to quantify the optical performance of each lens. Crosstalk and independence of tunability are discussed in the context of possible applications of the approach for general wavefront shaping.

Wave field synthesis of moving virtual sound sources with complex radiation properties.

PubMed

Ahrens, Jens; Spors, Sascha

2011-11-01

An approach to the synthesis of moving virtual sound sources with complex radiation properties in wave field synthesis is presented. The approach exploits the fact that any stationary sound source of finite spatial extent radiates spherical waves at sufficient distance. The angular dependency of the radiation properties of the source under consideration is reflected by the amplitude and phase distribution on the spherical wave fronts. The sound field emitted by a uniformly moving monopole source is derived and the far-field radiation properties of the complex virtual source under consideration are incorporated in order to derive a closed-form expression for the loudspeaker driving signal. The results are illustrated via numerical simulations of the synthesis of the sound field of a sample moving complex virtual source.

Cryogenic Optical Performance of a Lightweighted Mirror Assembly for Future Space Astronomical Telescopes: Correlating Optical Test Results and Thermal Optical Model

NASA Technical Reports Server (NTRS)

Eng, Ron; Arnold, William R.; Baker, Marcus A.; Bevan, Ryan M.; Burdick, Gregory; Effinger, Michael R.; Gaddy, Darrell E.; Goode, Brian K.; Hanson, Craig; Hogue, William D.;

Advanced figure sensor operations and maintenance manual

NASA Technical Reports Server (NTRS)

Robertson, H. J.

1972-01-01

This manual contains procedures for installing, operating, and maintaining the optical figure sensor and its associated electronic controls. The optical figure sensor, a system of integrated components, comprises: (1) a phase measuring modified interferometer employing a single frequency 6328 A laser, and a Vidissector; (2) a two-axis automatic thermal compensation control mount; (3) a five degree of freedom manual adjustment stand; and (4) a control console. This instrument provides real time output data of optical figure errors for spherical mirrors, and is also capable of measuring aspherical mirrors if a null corrector is added.

Optical elements formed by compressed gases: Analysis and potential applications

NASA Technical Reports Server (NTRS)

Howes, W. L.

1986-01-01

Spherical, cylindrical, and conical shock waves are optically analogous to gas lenses. The geometrical optics of these shock configurations are analyzed as they pertain to flow visualization instruments, particularly the rainbow schlieren apparatus and single-pass interferometers. It is proposed that a lens or mirror formed by gas compressed between plastic sheets has potential as a fluid visualization test object; as the objective mirror in a very large space-based telescope, communication antenna, or energy collector; as the objective mirror in inexpensive commercial telescopes; and as a component in fluid visualization apparatuses.

Prospects for the Thomson scattering system on NSTX-Upgrade.

PubMed

Diallo, A; LeBlanc, B P; Labik, G; Stevens, D

2012-10-01

The paper discusses the projected configuration of the Thomson system on the National Spherical Torus Experiment (NSTX-U). In this paper, we discuss the projected configuration of the Thomson system on NSTX-U. More specifically, we determine, through both optical modeling of the collection optics and in-vessel measurements, that the collecting fibers are to be displaced by at most 1 cm toward the imaging plane along the optical axis. Finally, we estimate the performance of the Thomson system in measuring the electron temperature for NSTX-U discharges.

Spherical loudspeaker array for local active control of sound.

PubMed

Rafaely, Boaz

2009-05-01

Active control of sound has been employed to reduce noise levels around listeners' head using destructive interference from noise-canceling sound sources. Recently, spherical loudspeaker arrays have been studied as multiple-channel sound sources, capable of generating sound fields with high complexity. In this paper, the potential use of a spherical loudspeaker array for local active control of sound is investigated. A theoretical analysis of the primary and secondary sound fields around a spherical sound source reveals that the natural quiet zones for the spherical source have a shell-shape. Using numerical optimization, quiet zones with other shapes are designed, showing potential for quiet zones with extents that are significantly larger than the well-known limit of a tenth of a wavelength for monopole sources. The paper presents several simulation examples showing quiet zones in various configurations.

Subjective Visual Performance and Objective Optical Quality With Intraocular Lens Glistening and Surface Light Scattering.

PubMed

Luo, Furong; Bao, Xuan; Qin, Yingyan; Hou, Min; Wu, Mingxing

2018-06-01

To evaluate the long-term effect of glistenings and surface light scattering of intraocular lenses (IOLs) on visual and optical performance after cataract surgery. Pseudophakic eyes that underwent standard phacoemulsification and two types of hydrophobic acrylic spherical IOL implantation without complications for at least 5 years were included in this retrospective study. Participants were divided into the glistenings, surface light scattering, and control groups according to the current condition of the IOLs. Then participants received a follow-up examination including uncorrected and corrected distance visual acuity (UDVA and CDVA), contrast sensitivity, straylight, and intraocular higher order aberrations, as well as point spread function (PSF) and modulation transfer function (MTF). A total of 140 eyes were included in the study. UDVA, CDVA, and glare sensitivity were not significantly different among the three groups (P > .05). However, compared with the control group, the IOLs of the glistenings and surface light scattering groups were associated with significantly lower contrast sensitivity under no glare conditions. Furthermore, eye with glistenings exhibited the highest straylight value (P < .05), whereas no difference was found between the surface light scattering and control groups. In contrast to the control group, the spherical aberration increased and the mean values of PSF and MTF decreased in the glistenings and surface light scattering groups. Both glistenings and surface light scattering tend to impair subjective visual performance, such as contrast sensitivity, and potentially affect objective optical quality, including straylight, spherical aberration, PSF, and MTF. [J Refract Surg. 2018;34(6):372-378.]. Copyright 2018, SLACK Incorporated.

Derivation of an optical potential for statically deformed rare-earth nuclei from a global spherical potential

DOE PAGES

Nobre, G. P. A.; Palumbo, A.; Herman, M.; ...

2015-02-25

The coupled-channel theory is a natural way of treating nonelastic channels, in particular those arising from collective excitations characterized by nuclear deformations. A proper treatment of such excitations is often essential to the accurate description of experimental nuclear-reaction data and to the prediction of a wide variety of scattering observables. Stimulated by recent work substantiating the near validity of the adiabatic approximation in coupled-channel calculations for scattering on statically deformed nuclei, we explore the possibility of generalizing a global spherical optical model potential (OMP) to make it usable in coupled-channel calculations on this class of nuclei. To do this, wemore » have deformed the Koning-Delaroche global spherical potential for neutrons, coupling a sufficient number of states of the ground state band to ensure convergence. We present an extensive study of the effects of collective couplings and nuclear deformations on integrated cross sections as well as on angular distributions for neutron-induced reactions on statically deformed nuclei in the rare-earth region. We choose isotopes of three rare-earth elements (Gd, Ho, W), which are known to be nearly perfect rotors, to exemplify the results of the proposed method. Predictions from our model for total, elastic and inelastic cross sections, as well as for elastic and inelastic angular distributions, are in reasonable agreement with measured experimental data. In conclusion, these results suggest that the deformed Koning-Delaroche potential provides a useful regional neutron optical potential for the statically deformed rare earth nuclei.« less

Spherical grating spectrometers

NASA Astrophysics Data System (ADS)

O'Donoghue, Darragh; Clemens, J. Christopher

2014-07-01

We describe designs for spectrometers employing convex dispersers. The Offner spectrometer was the first such instrument; it has almost exclusively been employed on satellite platforms, and has had little impact on ground-based instruments. We have learned how to fabricate curved Volume Phase Holographic (VPH) gratings and, in contrast to the planar gratings of traditional spectrometers, describe how such devices can be used in optical/infrared spectrometers designed specifically for curved diffraction gratings. Volume Phase Holographic gratings are highly efficient compared to conventional surface relief gratings; they have become the disperser of choice in optical / NIR spectrometers. The advantage of spectrometers with curved VPH dispersers is the very small number of optical elements used (the simplest comprising a grating and a spherical mirror), as well as illumination of mirrors off axis, resulting in greater efficiency and reduction in size. We describe a "Half Offner" spectrometer, an even simpler version of the Offner spectrometer. We present an entirely novel design, the Spherical Transmission Grating Spectrometer (STGS), and discuss exemplary applications, including a design for a double-beam spectrometer without any requirement for a dichroic. This paradigm change in spectrometer design offers an alternative to all-refractive astronomical spectrometer designs, using expensive, fragile lens elements fabricated from CaF2 or even more exotic materials. The unobscured mirror layout avoids a major drawback of the previous generation of catadioptric spectrometer designs. We describe laboratory measurements of the efficiency and image quality of a curved VPH grating in a STGS design, demonstrating, simultaneously, efficiency comparable to planar VPH gratings along with good image quality. The stage is now set for construction of a prototype instrument with impressive performance.

Scalable MWIR and LWIR optical system designs employing a large spherical primary mirror and small refractive aberration correctors

NASA Astrophysics Data System (ADS)

Beach, David A.

2001-12-01

Design variants of a recently developed optical imaging system have been computed for the thermal infrared spectral bands, which offer some advantages for long-range surveillance and astronomy. Only the spherical primary mirror has the full pupil diameter, all other components being sub-diameter, so scaling is possible up to relatively large pupils. Low-cost fabrication is enabled by the prevalence of spherical optical surfaces. Both MWIR and LWIR spectral transmissions are enabled by the choice of corrector materials, the examples given employing germanium and sapphire for 3.5 - 5.5 micrometers and germanium and zinc selenide for 3.5 - 5.5 micrometers and 8 - 12 micrometers passbands. Diffraction at these wavelengths is the main contributor to resolution constraints, so high numerical aperture values are preferred to enable a better match of blur spot diameter to generally available pixel dimensions. The systems described can routinely be designed to have speeds of f/0.8 or faster, while maintaining diffraction-limited performance over useful angular fields. Because the new design system employs a relayed catadioptric, it is possible to make the aperture stop of the system coincident with the window of the detector cryostat, enabling precise radiometric geometry. The central obscuration provides a convenient location for a calibration source, and both this and a mask for secondary spider supports can be included within the detector cold screen structure. Dual-band operation could be enabled by inclusion of a spectral beam splitter prior to a dual relay/imager system.

Absolute calibration of optical flats

DOEpatents

Sommargren, Gary E.

2005-04-05

The invention uses the phase shifting diffraction interferometer (PSDI) to provide a true point-by-point measurement of absolute flatness over the surface of optical flats. Beams exiting the fiber optics in a PSDI have perfect spherical wavefronts. The measurement beam is reflected from the optical flat and passed through an auxiliary optic to then be combined with the reference beam on a CCD. The combined beams include phase errors due to both the optic under test and the auxiliary optic. Standard phase extraction algorithms are used to calculate this combined phase error. The optical flat is then removed from the system and the measurement fiber is moved to recombine the two beams. The newly combined beams include only the phase errors due to the auxiliary optic. When the second phase measurement is subtracted from the first phase measurement, the absolute phase error of the optical flat is obtained.

Excitation of Cy5 in self-assembled lipid bilayers using optical microresonators

NASA Astrophysics Data System (ADS)

Freeman, Lindsay M.; Li, Su; Dayani, Yasaman; Choi, Hong-Seok; Malmstadt, Noah; Armani, Andrea M.

2011-04-01

Due to their sensitivity and temporal response, optical microresonators are used extensively in the biosensor arena, particularly in the development of label-free diagnostics and measurement of protein kinetics. In the present letter, we investigate using microcavities to probe molecules within biomimetic membranes. Specifically, a method for self-assembling lipid bilayers on spherical microresonators is developed and the bilayer-nature is verified. Subsequently, the microcavity is used to excite a Cy5-conjugated lipid located within the bilayer while the optical performance of the microcavity is characterized. The emission wavelength of the dye and the optical behavior of the microcavity agree with theoretical predictions.

Eye vision system using programmable micro-optics and micro-electronics

NASA Astrophysics Data System (ADS)

Riza, Nabeel A.; Amin, M. Junaid; Riza, Mehdi N.

2014-02-01

Proposed is a novel eye vision system that combines the use of advanced micro-optic and microelectronic technologies that includes programmable micro-optic devices, pico-projectors, Radio Frequency (RF) and optical wireless communication and control links, energy harvesting and storage devices and remote wireless energy transfer capabilities. This portable light weight system can measure eye refractive powers, optimize light conditions for the eye under test, conduct color-blindness tests, and implement eye strain relief and eye muscle exercises via time sequenced imaging. Described is the basic design of the proposed system and its first stage system experimental results for vision spherical lens refractive error correction.

Extended depth of focus adaptive optics spectral domain optical coherence tomography

PubMed Central

Sasaki, Kazuhiro; Kurokawa, Kazuhiro; Makita, Shuichi; Yasuno, Yoshiaki

2012-01-01

We present an adaptive optics spectral domain optical coherence tomography (AO-SDOCT) with a long focal range by active phase modulation of the pupil. A long focal range is achieved by introducing AO-controlled third-order spherical aberration (SA). The property of SA and its effects on focal range are investigated in detail using the Huygens-Fresnel principle, beam profile measurement and OCT imaging of a phantom. The results indicate that the focal range is extended by applying SA, and the direction of extension can be controlled by the sign of applied SA. Finally, we demonstrated in vivo human retinal imaging by altering the applied SA. PMID:23082278

FIBER AND INTEGRATED OPTICS: Compact fiber-optic compressor of ultrashort pulses

NASA Astrophysics Data System (ADS)

Nikitin, S. P.; Onishchukov, G. I.; Fomichev, A. A.

1992-02-01

A theoretical design of a universal compact fiber-optic compressor based on a monochromator with a spherical mirror in the plane of its exit slit was considered. Ultrashort pulses emitted by an actively mode-locked YAG:Nd3+ laser, whose spectrum was broadened in a fiber-optic waveguide, were compressed experimentally to 2.7 ns. A universal compact compressor was developed: it produced 4-ns pulses with an average radiation power of about 1 W. The dimensions of this compressor were several times smaller than those of a traditional scheme using a diffraction grating to compress pulses having an initial duration of about 100 ns.

Extended depth of focus adaptive optics spectral domain optical coherence tomography.

PubMed

Sasaki, Kazuhiro; Kurokawa, Kazuhiro; Makita, Shuichi; Yasuno, Yoshiaki

2012-10-01

We present an adaptive optics spectral domain optical coherence tomography (AO-SDOCT) with a long focal range by active phase modulation of the pupil. A long focal range is achieved by introducing AO-controlled third-order spherical aberration (SA). The property of SA and its effects on focal range are investigated in detail using the Huygens-Fresnel principle, beam profile measurement and OCT imaging of a phantom. The results indicate that the focal range is extended by applying SA, and the direction of extension can be controlled by the sign of applied SA. Finally, we demonstrated in vivo human retinal imaging by altering the applied SA.

Development of optical WGM resonators for biosensors

NASA Astrophysics Data System (ADS)

Brice, I.; Pirktina, A.; Ubele, A.; Grundsteins, K.; Atvars, A.; Viter, R.; Alnis, J.

2017-12-01

Whispering Gallery Mode (WGM) resonators are very sensitive to nanoparticles attaching to the surface. We simulate this process using COMSOL Wave Optics module. Our spherical WGM resonators are produced by melting a tip of an optical fiber and we measure optical Q factors in the 105 range. Molecular oxygen lines of the air in the 760 nm region are used as reference markers when looking for the shifts of the WGM resonance lines. We demonstrate WGM microresonator surface coating with a layer of ZnO nanorods as well as with polystyrene microspheres. Coatings produce increased contact surface. Additional layer of antigens/antibodies will be coated to make high-specificity biosensors.

Scintillation index and performance analysis of wireless optical links over non-Kolmogorov weak turbulence based on generalized atmospheric spectral model.

PubMed

Cang, Ji; Liu, Xu

2011-09-26

Based on the generalized spectral model for non-Kolmogorov atmospheric turbulence, analytic expressions of the scintillation index (SI) are derived for plane, spherical optical waves and a partially coherent Gaussian beam propagating through non-Kolmogorov turbulence horizontally in the weak fluctuation regime. The new expressions relate the SI to the finite turbulence inner and outer scales, spatial coherence of the source and spectral power-law and then used to analyze the effects of atmospheric condition and link length on the performance of wireless optical communication links. © 2011 Optical Society of America

Application of optical interferometry in focused acoustic field measurement

NASA Astrophysics Data System (ADS)

Wang, Yuebing; Sun, Min; Cao, Yonggang; Zhu, Jiang

2018-07-01

Optical interferometry has been successfully applied in measuring acoustic pressures in plane-wave fields and spherical-wave fields. In this paper, the "effective" refractive index for focused acoustic fields was developed, through numerical simulation and experiments, the feasibility of the optical method in measuring acoustic fields of focused transducers was proved. Compared with the results from a membrane hydrophone, it was concluded that the optical method has good spatial resolution and is suitable for detecting focused fields with fluctuant distributions. The influences of a few factors (the generated lamb wave, laser beam directivity, etc.) were analyzed, and corresponding suggestions were proposed for effective application of this technology.

Optical near-field analysis of spherical metals: Application of the FDTD method combined with the ADE method.

PubMed

Yamaguchi, Takashi; Hinata, Takashi

2007-09-03

The time-average energy density of the optical near-field generated around a metallic sphere is computed using the finite-difference time-domain method. To check the accuracy, the numerical results are compared with the rigorous solutions by Mie theory. The Lorentz-Drude model, which is coupled with Maxwell's equation via motion equations of an electron, is applied to simulate the dispersion relation of metallic materials. The distributions of the optical near-filed generated around a metallic hemisphere and a metallic spheroid are also computed, and strong optical near-fields are obtained at the rim of them.

Active optics null test system based on a liquid crystal programmable spatial light modulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ares, Miguel; Royo, Santiago; Sergievskaya, Irina

2010-11-10

We present an active null test system adapted to test lenses and wavefronts with complex shapes and strong local deformations. This system provides greater flexibility than conventional static null tests that match only a precisely positioned, individual wavefront. The system is based on a cylindrical Shack-Hartmann wavefront sensor, a commercial liquid crystal programmable phase modulator (PPM), which acts as the active null corrector, enabling the compensation of large strokes with high fidelity in a single iteration, and a spatial filter to remove unmodulated light when steep phase changes are compensated. We have evaluated the PPM's phase response at 635 nmmore » and checked its performance by measuring its capability to generate different amounts of defocus aberration, finding root mean squared errors below {lambda}/18 for spherical wavefronts with peak-to-valley heights of up to 78.7{lambda}, which stands as the limit from which diffractive artifacts created by the PPM have been found to be critical under no spatial filtering. Results of a null test for a complex lens (an ophthalmic customized progressive addition lens) are presented and discussed.« less

Trace-transform invariants of tracks of high-velocity jets from the surface of tungsten droplets in the plasma flow

NASA Astrophysics Data System (ADS)

Gulyaev, P.; Jordan, V.; Gulyaev, I.; Dolmatov, A.

2017-05-01

The paper presents the analysis of the recorded tracks of high-velocity emission in the air-argon plasma flow during breaking up of tungsten microdroplets. This new physical effect of optical emission involves two stages. The first one includes thermionic emission of electrons from the surface of the melted tungsten droplet of 100-200 μm size and formation of the charged sphere of 3-5 mm diameter. After it reaches the breakdown electric potential, it collapses and produces a spherical shock wave and luminous radiation. The second stage includes previously unknown physical phenomenon of narrowly directed energy jet with velocity exceeding 4000 m/s from the surface of the tungsten droplet. The luminous spherical collapse and high-velocity jets were recorded using CMOS photo-array operating in a global shutter charge storage mode. Special features of the CMOS array scanning algorithm affect formation of distinctive signs of the recorded tracks, which stay invariant to trace transform (TT) with specific functional. The series of concentric circles were adopted as primitive object models (patterns) used in TT at the spherical collapse stage and linear segment of fixed thickness - at the high-velocity emission stage. The two invariants of the physical object, motion velocity and optical brightness distribution in the motion front, were adopted as desired identification features of tracks. The analytical expressions of the relation of 2D TT parameters and physical object motion invariants were obtained. The equations for spherical collapse stage correspond to Radon-Nikodym transform.

The total spectral radiant flux calibration using a spherical spectrometer at National Institute of Metrology China

NASA Astrophysics Data System (ADS)

Zhao, Weiqiang; Liu, Hui; Liu, Jian

2016-11-01

At present day, in the field of lighting the incandescent lamps are phasing out. The solid state lighting products, i.e. LED, and the related market are developing very fast in China for its promising application, due to the energy-saving and the colorful features. For the quality control and the commercial trade purpose, it is highly necessary to measure the optical parameters of LED light sources with a fast, easy and affordable facility. Therefore, more test labs use the spherical spectrometer to measure LED. The quasi- monochrome of LED and the V(lambda) of silicon photodetector mismatch problem is reduced or avoided, because the total spectral radiant flux (TSRF) is measured, and all the optical parameters are calculate from the TSRF. In such a way, the spherical spectrometer calibration requires TSRF standard lamps instead of the traditional total flux standard lamps. National Institute of Metrology China (NIM) has studied and developed the facilities for TSRF measurement and provides related calibration services. This paper shows the TSRF standard lamp calibration procedure using a spherical spectrometer in every-day calibration and its traceable link to the primary SI unit at NIM. The sphere is of 1.5 m diameter, and installed with a spectrometer and a silicon photodetector. It also shows the detail of data process, such as the spectral absorption correction method and the calculation of the result derived from the spectral readings. The TSRF calibration covers the spectra range of 350 nm to 1050 nm, with a measurement uncertainty of 3.6% 1.8% (k=2).

Plasmonic Spherical Heterodimers: Reversal of Optical Binding Force Based on the Forced Breaking of Symmetry.

PubMed

Mahdy, M R C; Danesh, Md; Zhang, Tianhang; Ding, Weiqiang; Rivy, Hamim Mahmud; Chowdhury, Ariful Bari; Mehmood, M Q

2018-02-16

The stimulating connection between the reversal of near-field plasmonic binding force and the role of symmetry-breaking has not been investigated comprehensively in the literature. In this work, the symmetry of spherical plasmonic heterodimer-setup is broken forcefully by shining the light from a specific side of the set-up instead of impinging it from the top. We demonstrate that for the forced symmetry-broken spherical heterodimer-configurations: reversal of lateral and longitudinal near-field binding force follow completely distinct mechanisms. Interestingly, the reversal of longitudinal binding force can be easily controlled either by changing the direction of light propagation or by varying their relative orientation. This simple process of controlling binding force may open a novel generic way of optical manipulation even with the heterodimers of other shapes. Though it is commonly believed that the reversal of near-field plasmonic binding force should naturally occur for the presence of bonding and anti-bonding modes or at least for the Fano resonance (and plasmonic forces mostly arise from the surface force), our study based on Lorentz-force dynamics suggests notably opposite proposals for the aforementioned cases. Observations in this article can be very useful for improved sensors, particle clustering and aggregation.

Optical aberrations induced by subclinical decentrations of the ablation pattern

NASA Astrophysics Data System (ADS)

Mrochen, Michael; Kaemmerer, Maik; Riedel, Peter; Mierdel, Peter; Krinke, Hans-Eberhard; Seiler, Theo

2000-06-01

Purpose: The aim of this work was to study the effect of currently used ablation profiles along with eccentric ablations on the increase of higher order aberrations observed after PRK. Material and Methods: The optical aberrations of 10 eyes were tested before and after PRK. Refractive surgery was performed using a ArF-excimer laser system. In all cases, the ablation zone was 6 mm or larger. The spherical equivalent of the correction was ranging from -2.5 D to -6.0 D. The measured wavefront error was compared to numerical simulations done with the reduced eye model and currently used ablation profiles as well as compared with experimental results obtained from ablation on PMMA balls. Results: The aberration measurements result in a considerable change of the spherical- and coma-like wavefront errors. This result was in good correlation with the numerical simulations and the experimental results. Furthermore, it has been derived that the major contribution on the induced higher order aberrations are a result of the small decentration (less than 1.0 mm) of the ablation zone. Conclusions: Higher order spherical- and coma-like aberrations after PRK are mainly determined by the decentration of the ablation zone during laser refractive surgery. However, future laser systems should use efficient eye-tracking systems and aspherical ablation profiles to overcome this problem.

Influence of the Doppler effect on radiative transfer in a spherical plasma under macroscopic motion of substance

NASA Astrophysics Data System (ADS)

Kosarev, N. I.

2018-03-01

The non-LTE radiative transfer in spherical plasma containing resonantly absorbing light ions has been studied numerically under conditions of macroscopic motion of substance. Two types of macroscopic motion were simulated: radial expansion and compression (pulsation) of spherical plasma; rotation of plasma relative to an axis of symmetry. The calculations of absorption line profile of transmitted broadband radiation and the emission line profile were performed for the optically dense plasma of calcium ions on the resonance transition with wavelength 397 nm. Numerical results predict frequency shifts in the emission line profile to red wing of the spectrum for radial expansion of the plasma and to blue wing of the spectrum for the plasma compression at an average velocity of ions along the ray of sight equal to zero. The width of the emission line profile of a rotating plasma considerably exceeds the width of the profile of the static plasma, and the shift of the central frequency of resonance transition from the resonance frequency of the static plasma gives a linear velocity of ion motion along a given ray trajectory in units of thermal velocity. Knowledge of the linear radial velocity of ions can be useful for diagnostic purposes in determining the frequency and period of rotation of optically dense plasmas.

Terahertz acoustic phonon detection from a compact surface layer of spherical nanoparticles powder mixture of aluminum, alumina and multi-walled carbon nanotube

NASA Astrophysics Data System (ADS)

Abouelsayed, A.; Ebrahim, M. R.; El hotaby, W.; Hassan, S. A.; Al-Ashkar, Emad

2017-10-01

We present terahertz spectroscopy study on spherical nanoparticles powder mixture of aluminum, alumina, and MWCNTs induced by surface mechanical attrition treatment (SMAT) of aluminum substrates. Surface alloying of AL, Al2O3 0.95% and MWCNTs 0.05% powder mixture was produced during SMAT process, where a compact surface layer of about 200 μm due to ball bombardment was produced from the mixture. Al2O3 alumina powder played a significant role in MWCNTs distribution on surface, those were held in deformation surface cites of micro-cavities due to SMAT process of Al. The benefits are the effects on resulted optical properties of the surface studied at the terahertz frequency range due to electrical isolation confinement effects and electronic resonance disturbances exerted on Al electronic resonance at the same range of frequencies. THz acoustic phonon around 0.53-0.6 THz (17-20 cm-1) were observed at ambient conditions for the spherical nanoparticles powder mixture of Al, Al2O3 and MWCNTs. These results suggested that the presence of Al2O3 and MWCNTs during SMAT process leads to the optically detection of such acoustic phonon in the THz frequency range.

Broadband, Achromatic Twyman-Green Interferometer

NASA Technical Reports Server (NTRS)

Steimle, Lawrence J.

1991-01-01

Improved Twyman-Green interferometer used in wave-front testing optical components at wavelengths from 200 to 1,100 nm, without having to readjust focus when changing wavelength. Built to measure aberrations of light passing through optical filters. Collimating and imaging lenses of classical Twyman-Green configuration replaced by single spherical mirror. Field lens replaced by field mirror. Mirrors exhibit no axial chromatic aberration and made to reflect light efficiently over desired broad range of wavelengths.

Generating high-quality single droplets for optical particle characterization with an easy setup

NASA Astrophysics Data System (ADS)

Xu, Jie; Ge, Baozhen; Meng, Rui

2018-06-01

The high-performance and micro-sized single droplet is significant for optical particle characterization. We develop a single-droplet generator (SDG) based on a piezoelectric inkjet technique with advantages of low cost and easy setup. By optimizing the pulse parameters, we achieve various size single droplets. Further investigations reveal that SDG generates single droplets of high quality, demonstrating good sphericity, monodispersity and a stable length of several millimeters.

Determination of Graphite-Liquid-Vapor Triple Point by Laser Heating

DTIC Science & Technology

1976-01-30

difficulties in the temperature measure- ments, which were made with an optical pyrometer . He considered that the failure of graphite rod was caused by...temperature measurements were made with a calibrated optical pyrometer . Spherical shiny frozen droplets of graphite, 1 to 3 mm in diameter, indicated...0.8 mm in diameter and 10 mm long in argon until failure by rupture occurred. They measured the tempera- ture with a two-color pyrometer . The

Bio-optical sensor for brain activity measurement based on whispering gallery modes

NASA Astrophysics Data System (ADS)

Ali, Amir R.; Massoud, Yasmin M.

2017-05-01

In this paper, a high-resolution bio-optical sensor is developed for brain activity measurement. The aim is to develop an optical sensor with enough sensitivity to detect small electric field perturbations caused by neuronal action potential. The sensing element is a polymeric dielectric micro-resonator fabricated in a spherical shape with a few hundred microns in diameter. They are made of optical quality polymers that are soft which make them mechanically compatible with tissue. The sensors are attached to or embedded in optical fibers which serve as input/output conduits for the sensors. Hundreds or even thousands of spheres can be attached to a single fiber to detect and transmit signals at different locations. The high quality factor for the optical resonator makes it significantly used in such bio-medical applications. The sensing phenomenon is based on whispering gallery modes (WGM) shifts of the optical sensor. To mimic the brain signals, the spherical resonator is immersed in a homogeneous electrical field that is created by applying potential difference across two metallic plates. One of the plates has a variable voltage while the volt on the other plate kept fixed. Any small perturbations of the potential difference (voltage) lead to change in the electric field intensity. In turn the sensor morphology will be affected due to the change in the electrostriction force acting on it causing change in its WGM. By tracking these WGM shift on the transmission spectrum, the induced potential difference (voltage change) could be measured. Results of a mathematical model simulation agree well with the preliminary experiments. Also, the results show that the brain activity could be measured using this principle.

Approximating high angular resolution apparent diffusion coefficient profiles using spherical harmonics under BiGaussian assumption

NASA Astrophysics Data System (ADS)

Cao, Ning; Liang, Xuwei; Zhuang, Qi; Zhang, Jun

2009-02-01

Magnetic Resonance Imaging (MRI) techniques have achieved much importance in providing visual and quantitative information of human body. Diffusion MRI is the only non-invasive tool to obtain information of the neural fiber networks of the human brain. The traditional Diffusion Tensor Imaging (DTI) is only capable of characterizing Gaussian diffusion. High Angular Resolution Diffusion Imaging (HARDI) extends its ability to model more complex diffusion processes. Spherical harmonic series truncated to a certain degree is used in recent studies to describe the measured non-Gaussian Apparent Diffusion Coefficient (ADC) profile. In this study, we use the sampling theorem on band-limited spherical harmonics to choose a suitable degree to truncate the spherical harmonic series in the sense of Signal-to-Noise Ratio (SNR), and use Monte Carlo integration to compute the spherical harmonic transform of human brain data obtained from icosahedral schema.

Synthesis of SiC nanoparticles by SHG 532 nm Nd:YAG laser ablation of silicon in ethanol

NASA Astrophysics Data System (ADS)

Khashan, Khawla S.; Ismail, Raid A.; Mahdi, Rana O.

2018-06-01

In this work, colloidal spherical nanoparticles NPs of silicon carbide SiC have been synthesized using second harmonic generation 532 nm Nd:YAG laser ablation of silicon target dipped in ethanol solution at various laser fluences (1.5-5) J/cm2. X-Ray diffraction XRD, scanning electron microscopy SEM, transmission electron microscope TEM, Fourier transformed infrared spectroscopy FT-IR, Raman spectroscopy, photoluminescence PL spectroscopy, and UV-Vis absorption were employed to examine the structural, chemical and optical properties of SiC NPs. XRD results showed that all synthesised SiC nanoparticles are crystalline in nature and have hexagonal structure with preferred orientation along (103) plane. Raman investigation showed three characteristic peaks 764,786 and 954 cm-1, which are indexing to transverse optic TO phonon mode and longitudinal optic LO phonon mode of 4H-SiC structure. The optical absorption data showed that the values of optical energy gap of SiC nanoparticles prepared at 1.5 J/cm2 was 3.6 eV and was 3.85 eV for SiC synthesised at 5 J/cm2. SEM investigations confirmed that the nanoparticles synthesised at 5 J/cm2 are agglomerated to form larger particles. TEM measurements showed that SiC particles prepared at 1.5 J/cm2 have spherical shape with average size of 25 nm, while the particles prepared at 5 J/cm2 have an average size of 55 nm.

Partial Wave Analysis of Coupled Photonic Structures

NASA Technical Reports Server (NTRS)

Fuller, Kirk A.; Smith, David D.; Curreri, Peter A. (Technical Monitor)

2002-01-01

The very high quality factors sustained by microcavity optical resonators are relevant to applications in wavelength filtering, routing, switching, modulation, and multiplexing/demultiplexing. Increases in the density of photonic elements require that attention be paid to how electromagnetic (EM) coupling modifies their optical properties. This is especially true when cavity resonances are involved, in which case, their characteristics may be fundamentally altered. Understanding the optical properties of microcavities that are near or in contact with photonic elements---such as other microcavities, nanostructures, couplers, and substrates---can be expected to advance our understanding of the roles that these structures may play in VLSI photonics, biosensors and similar device technologies. Wc present results from recent theoretical studies of the effects of inter- and intracavity coupling on optical resonances in compound spherical particles. Concentrically stratified spheres and bispheres constituted from homogeneous and stratified spheres are subjects of this investigation. A new formulation is introduced for the absorption of light in an arbitrary layer of a multilayered sphere, which is based on multiple reflections of the spherical partial waves of the Lorenz-Mie solution for scattering by a sphere. Absorption efficiencies, which can be used to profile cavity resonances and to infer fluorescence yields or the onset of nonlinear optical processes in the microcavities, are presented. Splitting of resonances in these multisphere systems is paid particular attention, and consequences for photonic device development and possible performance enhancements through carefully designed architectures that exploit EM coupling are considered.

Computer modeling of the optical properties and heating of spherical gold and silica-gold nanoparticles for laser combined imaging and photothermal treatment.

PubMed

Pustovalov, V; Astafyeva, L; Jean, B

2009-06-03

Recently, several groups of investigators (Anderson, Halas, Zharov, El-Sayed and their co-workers (Pitsillides et al 2003 Biophys. J. 84 4023-31, Zharov et al 2003 Appl. Phys. Lett. 83 4897-9, Zharov et al 2004 Proc. SPIE 5319 291-9, Loo et al 2005 Nano Lett. 5 709-11, Gobin et al 2007 Nano Lett. 7 1929-34, Fu et al 2008 Nanotechnology 19 045103, Huang et al 2006 J. Am. Chem. Soc. 128 2115-20, Jain et al 2006 J. Phys. Chem. B 110 7238-48, Jain et al 2007 Nano Today 2 18-29)) demonstrated, through pioneering results, the great potential of laser thermal therapy of cells and tissues conjugated with gold nanoparticles. It was also proposed to use combined diagnostics and therapy on the basis of nanoparticle selection for achievement of efficient contrast for laser imaging applications, as well as for photothermal therapy. However, the current understanding of the relationship between optical properties (absorption, backscattering) of nanoparticles, the efficiency of nanoparticle heating and the possibility to use them for combined imaging and therapy is limited. Here, we report the results of computer modeling of optical absorption and backscattering properties and laser heating of gold and silica-gold spherical nanoparticles for laser combined imaging and photothermal treatment of cells and tissues conjugated with nanoparticles. The efficiencies of nanoparticle heating and backscattering by nanoparticles, depending upon their radii, structure and optical properties of the metal, were investigated. This paper focuses on the analysis and determination of appropriate ranges of nanoparticle sizes for the purposes of laser combined imaging and photothermal treatment. The possibility to use spherical gold and silica-gold nanoparticles in determined ranges of radii for these purposes for laser wavelengths 532 and 800 nm is investigated.

Impact of Radiatively Interactive Dust Aerosols in the NASA GEOS-5 Climate Model: Sensitivity to Dust Particle Shape and Refractive Index

NASA Technical Reports Server (NTRS)

Colarco, Peter R.; Nowottnick, Edward Paul; Randles, Cynthia A.; Yi, Bingqi; Yang, Ping; Kim, Kyu-Myong; Smith, Jamison A.; Bardeen, Charles D.

2013-01-01

We investigate the radiative effects of dust aerosols in the NASA GEOS-5 atmospheric general circulation model. GEOS-5 is improved with the inclusion of a sectional aerosol and cloud microphysics module, the Community Aerosol and Radiation Model for Atmospheres (CARMA). Into CARMA we introduce treatment of the dust and sea salt aerosol lifecycle, including sources, transport evolution, and sinks. The aerosols are radiatively coupled to GEOS-5, and we perform a series of multi-decade AMIP-style simulations in which dust optical properties (spectral refractive index and particle shape distribution) are varied. Optical properties assuming spherical dust particles are from Mie theory, while those for non-spherical shape distributions are drawn from a recently available database for tri-axial ellipsoids. The climatologies of the various simulations generally compare well to data from the MODIS, MISR, and CALIOP space-based sensors, the ground-based AERONET, and surface measurements of dust deposition and concentration. Focusing on the summertime Saharan dust cycle we show significant variability in our simulations resulting from different choices of dust optical properties. Atmospheric heating due to dust enhances surface winds over important Saharan dust sources, and we find a positive feedback where increased dust absorption leads to increased dust emissions. We further find that increased dust absorption leads to a strengthening of the summertime Hadley cell circulation, increasing dust lofting to higher altitudes and strengthening the African Easterly Jet. This leads to a longer atmospheric residence time, higher altitude, and generally more northward transport of dust in simulations with the most absorbing dust optical properties. We find that particle shape, although important for radiance simulations, is a minor effect compared to choices of refractive index, although total atmospheric forcing is enhanced by greater than 10 percent for simulations incorporating a spheroidal shape distribution versus ellipsoidal or spherical shapes.

Computational and Experimental Investigation of Interfacial Area in Near-Field Diesel Spray Simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pandal, Adrian; Pastor, Jose M.; Payri, Raul

The dense spray region in the near-field of diesel fuel injection remains an enigma. This region is difficult to interrogate with light in the visible range and difficult to model due to the rapid interaction between liquid and gas. In particular, modeling strategies that rely on Lagrangian particle tracking of droplets have struggled in this area. To better represent the strong interaction between phases, Eulerian modeling has proven particularly useful. Models built on the concept of surface area density are advantageous where primary and secondary atomization have not yet produced droplets, but rather form more complicated liquid structures. Surface areamore » density, a more general concept than Lagrangian droplets, naturally represents liquid structures, no matter how complex. These surface area density models, however, have not been directly experimentally validated in the past due to the inability of optical methods to elucidate such a quantity. Optical diagnostics traditionally measure near-spherical droplet size far downstream, where the spray is optically thin. Using ultra-small-angle x-ray scattering (USAXS) measurements to measure the surface area and x-ray radiography to measure the density, we have been able to test one of the more speculative parts of Eulerian spray modeling. In conclusion, the modeling and experimental results have been combined to provide insight into near-field spray dynamics.« less

Computational and Experimental Investigation of Interfacial Area in Near-Field Diesel Spray Simulation

DOE PAGES

Pandal, Adrian; Pastor, Jose M.; Payri, Raul; ...

2017-03-28

The dense spray region in the near-field of diesel fuel injection remains an enigma. This region is difficult to interrogate with light in the visible range and difficult to model due to the rapid interaction between liquid and gas. In particular, modeling strategies that rely on Lagrangian particle tracking of droplets have struggled in this area. To better represent the strong interaction between phases, Eulerian modeling has proven particularly useful. Models built on the concept of surface area density are advantageous where primary and secondary atomization have not yet produced droplets, but rather form more complicated liquid structures. Surface areamore » density, a more general concept than Lagrangian droplets, naturally represents liquid structures, no matter how complex. These surface area density models, however, have not been directly experimentally validated in the past due to the inability of optical methods to elucidate such a quantity. Optical diagnostics traditionally measure near-spherical droplet size far downstream, where the spray is optically thin. Using ultra-small-angle x-ray scattering (USAXS) measurements to measure the surface area and x-ray radiography to measure the density, we have been able to test one of the more speculative parts of Eulerian spray modeling. In conclusion, the modeling and experimental results have been combined to provide insight into near-field spray dynamics.« less

Multifunctionality of chiton biomineralized armor with an integrated visual system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Ling; Connors, Matthew; Kolle, Mathias

2015-11-20

Nature provides a multitude of examples of multifunctional structural materials. There are often trade-offs in these materials because few of them are equally well suited for multiple tasks. One such example is the biomineralized armor of the chiton Acanthopleura granulata, which incorporates an integrated sensory system that includes hundreds of eyes with aragonite-based lens. Here, we used optical experiments to demonstrate directly, for the first time, that these microscopic, mineralized lenses are able to form images. Furthermore, our experiments revealed that the optical performance of these polycrystalline lenses is enhanced by the reduction of spherical aberration through the shape ofmore » the lens and that birefringence scattering is minimized by the use of relatively large, co-aligned grains (~10 μm as compared to ~1 μm in the non-eye regions). Additionally, we used multi-scale mechanical testing techniques to show that A. granulata’s lenses are an integral component of its biomineralized armor, but that both the intrinsic and overall mechanical properties of the lenses are compromised as compared to the primary solid regions of the armor plates. Our results demonstrate that as the size, complexity, and functionality of the integrated sensory elements increases, the local mechanical performance of the armor decreases. But, A. granulata has evolved several strategies to compensate for its local mechanical vulnerabilities to form a multifunctional system with co-optimized overall optical and structural functions.« less

A scalable multi-DLP pico-projector system for virtual reality

NASA Astrophysics Data System (ADS)

Teubl, F.; Kurashima, C.; Cabral, M.; Fels, S.; Lopes, R.; Zuffo, M.

2014-03-01

Virtual Reality (VR) environments can offer immersion, interaction and realistic images to users. A VR system is usually expensive and requires special equipment in a complex setup. One approach is to use Commodity-Off-The-Shelf (COTS) desktop multi-projectors manually or camera based calibrated to reduce the cost of VR systems without significant decrease of the visual experience. Additionally, for non-planar screen shapes, special optics such as lenses and mirrors are required thus increasing costs. We propose a low-cost, scalable, flexible and mobile solution that allows building complex VR systems that projects images onto a variety of arbitrary surfaces such as planar, cylindrical and spherical surfaces. This approach combines three key aspects: 1) clusters of DLP-picoprojectors to provide homogeneous and continuous pixel density upon arbitrary surfaces without additional optics; 2) LED lighting technology for energy efficiency and light control; 3) smaller physical footprint for flexibility purposes. Therefore, the proposed system is scalable in terms of pixel density, energy and physical space. To achieve these goals, we developed a multi-projector software library called FastFusion that calibrates all projectors in a uniform image that is presented to viewers. FastFusion uses a camera to automatically calibrate geometric and photometric correction of projected images from ad-hoc positioned projectors, the only requirement is some few pixels overlapping amongst them. We present results with eight Pico-projectors, with 7 lumens (LED) and DLP 0.17 HVGA Chipset.

Jetting from impact of a spherical drop with a deep layer

NASA Astrophysics Data System (ADS)

Zhang, Li; Toole, Jameson; Fazzaa, Kamel; Deegan, Robert; Deegan Group Team; X-Ray Science Division, Advanced Photon Source Collaboration

2011-11-01

We performed an experimental study of jets during the impact of a spherical drop with a deep layer of same liquid. Using high speed optical and X-ray imaging, we observe two types of jets: the so-called ejecta sheet which emerges almost immediately after impact and the lamella which emerges later. For high Reynolds number the two jets are distinct, while for low Reynolds number the two jets combine into a single continuous jet. We also measured the emergence time, speed, and position of the ejecta sheet and found simple scaling relations for these quantities.

Inducing Lift on Spherical Particles by Traveling Magnetic Fields

NASA Technical Reports Server (NTRS)

Mazuruk, Konstantin; Grugel, Richard N.; Rose, M. Franklin (Technical Monitor)

2001-01-01

Gravity induced sedimentation of suspensions is a serious drawback to many materials and biotechnology processes, a factor that can, in principle, be overcome by utilizing an opposing Lorentz body force. In this work we demonstrate the utility of employing a traveling magnetic field (TMF) to induce a lifting force on particles dispersed in the fluid. Theoretically, a model has been developed to ascertain the net force, induced by TMF, acting on a spherical body as a function of the fluid medium's electrical conductivity and other parameters. Experimentally, the model is compared to optical observations of particle motion in the presence of TMF.

Inducing Lift on Spherical Particles by Traveling Magnetic Fields

NASA Technical Reports Server (NTRS)

Mazuruk, Konstantin; Grugel, Richard N.; Rose, M. Franklin (Technical Monitor)

2000-01-01

Gravity induced sedimentation of suspensions is a serious drawback to many materials and biotechnology processes, a factor that can, in principle, be overcome by utilizing an opposing Lorentz body force. In this work we demonstrate the utility of employing a traveling magnetic field (TMF) to induce a lifting force on particles dispersed in the fluid. Theoretically, a model has been developed to ascertain the net force, induced by TMF, acting on a spherical body as a function of the fluid medium's electrical conductivity and other parameters. Experimentally, the model is compared to optical observations of particle motion in the presence of TMF.

Analysis of fine-mode aerosol retrieval capabilities by different passive remote sensing instrument designs.

PubMed

Knobelspiesse, Kirk; Cairns, Brian; Mishchenko, Michael; Chowdhary, Jacek; Tsigaridis, Kostas; van Diedenhoven, Bastiaan; Martin, William; Ottaviani, Matteo; Alexandrov, Mikhail

2012-09-10

Remote sensing of aerosol optical properties is difficult, but multi-angle, multi-spectral, polarimetric instruments have the potential to retrieve sufficient information about aerosols that they can be used to improve global climate models. However, the complexity of these instruments means that it is difficult to intuitively understand the relationship between instrument design and retrieval success. We apply a Bayesian statistical technique that relates instrument characteristics to the information contained in an observation. Using realistic simulations of fine size mode dominated spherical aerosols, we investigate three instrument designs. Two of these represent instruments currently in orbit: the Multiangle Imaging SpectroRadiometer (MISR) and the POLarization and Directionality of the Earths Reflectances (POLDER). The third is the Aerosol Polarimetry Sensor (APS), which failed to reach orbit during recent launch, but represents a viable design for future instruments. The results show fundamental differences between the three, and offer suggestions for future instrument design and the optimal retrieval strategy for current instruments. Generally, our results agree with previous validation efforts of POLDER and airborne prototypes of APS, but show that the MISR aerosol optical thickness uncertainty characterization is possibly underestimated.

Phase behavior and transitions of self-assembling nano-structured materials

NASA Astrophysics Data System (ADS)

Duan, Hu

Homologous series of supramolecular nanostructures have been investigated by a combination of transmission electron microscopy (TEM), electron diffraction (ED), thermal polarized optical microscopy and X-ray diffraction (XRD). Materials include amphiphilic oligomers and polymer such as charged complexes, dipeptide dendrons semi-fluorinated dendron and polyethyleneimines. Upon microphase separation, they self-assemble into either cylindrical or spherical shapes, which co-organize into a 2D P6mm hexagonal columnar phase or 3D Pm 3¯ n and Im 3¯ m cubic phases. Correlation between the phase selection and molecular architecture is established accordingly. The order-disorder transition (ODT) is explored by rheometry and rheo-optical microscopy in a model polymeric compound poly(N-[3,4-bis(n-dodecan-1-yloxy)benzoyl]ethyleneimine). Shear alignment of the hexagonal columnar liquid crystalline phase along the velocity direction at low temperature and shear disordering in the vicinity of the ODT were observed. After cessation of shear, transformation back to the stable columnar phase follows a row-nucleation mechanism. The order-order transition process is explored in a monodendron that exhibits a hexagonal columnar and a weakly birefringent mesophase. Polarized DIC microscopy strongly supports an epitaxial relationship between them.

Comparison-based optical study on a point-line-coupling-focus system with linear Fresnel heliostats.

PubMed

Dai, Yanjun; Li, Xian; Zhou, Lingyu; Ma, Xuan; Wang, Ruzhu

2016-05-16

Concentrating the concept of a beam-down solar tower with linear Fresnel heliostat (PLCF) is one of the feasible choices and has great potential in reducing spot size and improving optical efficiency. Optical characteristics of a PLCF system with the hyperboloid reflector are introduced and investigated theoretically. Taking into account solar position and optical surface errors, a Monte Carlo ray-tracing (MCRT) analysis model for a PLCF system is developed and applied in a comparison-based study on the optical performance between the PLCF system and the conventional beam-down solar tower system with flat and spherical heliostats. The optimal square facet of linear Fresnel heliostat is also proposed for matching with the 3D-CPC receiver.

Calcitic microlenses as part of the photoreceptor system in brittlestars

NASA Astrophysics Data System (ADS)

Aizenberg, Joanna; Tkachenko, Alexei; Weiner, Steve; Addadi, Lia; Hendler, Gordon

2001-08-01

Photosensitivity in most echinoderms has been attributed to `diffuse' dermal receptors. Here we report that certain single calcite crystals used by brittlestars for skeletal construction are also a component of specialized photosensory organs, conceivably with the function of a compound eye. The analysis of arm ossicles in Ophiocoma showed that in light-sensitive species, the periphery of the labyrinthic calcitic skeleton extends into a regular array of spherical microstructures that have a characteristic double-lens design. These structures are absent in light-indifferent species. Photolithographic experiments in which a photoresist film was illuminated through the lens array showed selective exposure of the photoresist under the lens centres. These results provide experimental evidence that the microlenses are optical elements that guide and focus the light inside the tissue. The estimated focal distance (4-7µm below the lenses) coincides with the location of nerve bundles-the presumed primary photoreceptors. The lens array is designed to minimize spherical aberration and birefringence and to detect light from a particular direction. The optical performance is further optimized by phototropic chromatophores that regulate the dose of illumination reaching the receptors. These structures represent an example of a multifunctional biomaterial that fulfills both mechanical and optical functions.

Aberration correction considering curved sample surface shape for non-contact two-photon excitation microscopy with spatial light modulator.

PubMed

Matsumoto, Naoya; Konno, Alu; Inoue, Takashi; Okazaki, Shigetoshi

2018-06-18

In this paper, excitation light wavefront modulation is performed considering the curved sample surface shape to demonstrate high-quality deep observation using two-photon excitation microscopy (TPM) with a dry objective lens. A large spherical aberration typically occurs when the refractive index (RI) interface between air and the sample is a plane perpendicular to the optical axis. Moreover, the curved sample surface shape and the RI mismatch cause various aberrations, including spherical ones. Consequently, the fluorescence intensity and resolution of the obtained image are degraded in the deep regions. To improve them, we designed a pre-distortion wavefront for correcting the aberration caused by the curved sample surface shape by using a novel, simple optical path length difference calculation method. The excitation light wavefront is modulated to the pre-distortion wavefront by a spatial light modulator incorporated in the TPM system before passing through the interface, where the RI mismatch occurs. Thus, the excitation light is condensed without aberrations. Blood vessels were thereby observed up to an optical depth of 2,000 μm in a cleared mouse brain by using a dry objective lens.

Water window imaging x ray microscope

NASA Technical Reports Server (NTRS)

Hoover, Richard B. (Inventor)

1992-01-01

A high resolution x ray microscope for imaging microscopic structures within biological specimens has an optical system including a highly polished primary and secondary mirror coated with identical multilayer coatings, the mirrors acting at normal incidence. The coatings have a high reflectivity in the narrow wave bandpass between 23.3 and 43.7 angstroms and have low reflectivity outside of this range. The primary mirror has a spherical concave surface and the secondary mirror has a spherical convex surface. The radii of the mirrors are concentric about a common center of curvature on the optical axis of the microscope extending from the object focal plane to the image focal plane. The primary mirror has an annular configuration with a central aperture and the secondary mirror is positioned between the primary mirror and the center of curvature for reflecting radiation through the aperture to a detector. An x ray filter is mounted at the stage end of the microscope, and film sensitive to x rays in the desired band width is mounted in a camera at the image plane of the optical system. The microscope is mounted within a vacuum chamber for minimizing the absorption of x rays in air from a source through the microscope.

Optical fabrication and testing; Proceedings of the Meeting, Singapore, Oct. 22-27, 1990

NASA Astrophysics Data System (ADS)

Lorenzen, Manfred; Campbell, Duncan R.; Johnson, Craig W.

1991-03-01

Various papers on optical fabrication and testing are presented. Individual topics addressed include: interferometry with laser diodes, new methods for economic production of prisms and lenses, interferometer accuracy and precision, optical testing with wavelength scanning interferometer, digital Talbot interferometer, high-sensitivity interferometric technique for strain measurements, absolute interferometric testing of spherical surfaces, contouring using gratings created on an LCD panel, three-dimensional inspection using laser-based dynamic fringe projection, noncontact optical microtopography, laser scan microscope and infrared laser scan microscope, photon scanning tunneling microscopy. Also discussed are: combination-matching problems in the layout design of minilaser rangefinder, design and testing of a cube-corner array for laser ranging, mode and far-field pattern of diode laser-phased arrays, new glasses for optics and optoelectronics, optical properties of Li-doped ZnO films, application and machining of Zerodur for optical purposes, finish machining of optical components in mass production.

Coherence degree of the fundamental Bessel-Gaussian beam in turbulent atmosphere

NASA Astrophysics Data System (ADS)

Lukin, Igor P.

2017-11-01

In this article the coherence of a fundamental Bessel-Gaussian optical beam in turbulent atmosphere is analyzed. The problem analysis is based on the solution of the equation for the transverse second-order mutual coherence function of a fundamental Bessel-Gaussian optical beam of optical radiation. The behavior of a coherence degree of a fundamental Bessel-Gaussian optical beam depending on parameters of an optical beam and characteristics of turbulent atmosphere is examined. It was revealed that at low levels of fluctuations in turbulent atmosphere the coherence degree of a fundamental Bessel-Gaussian optical beam has the characteristic oscillating appearance. At high levels of fluctuations in turbulent atmosphere the coherence degree of a fundamental Bessel-Gaussian optical beam is described by an one-scale decreasing curve which in process of increase of level of fluctuations on a line of formation of a laser beam becomes closer to the same characteristic of a spherical optical wave.

Optical fabrication and testing; Proceedings of the Meeting, Singapore, Oct. 22-27, 1990

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lorenzen, M.; Campbell, D.R.; Johnson, C.W.

1991-01-01

Various papers on optical fabrication and testing are presented. Individual topics addressed include: interferometry with laser diodes, new methods for economic production of prisms and lenses, interferometer accuracy and precision, optical testing with wavelength scanning interferometer, digital Talbot interferometer, high-sensitivity interferometric technique for strain measurements, absolute interferometric testing of spherical surfaces, contouring using gratings created on an LCD panel, three-dimensional inspection using laser-based dynamic fringe projection, noncontact optical microtopography, laser scan microscope and infrared laser scan microscope, photon scanning tunneling microscopy. Also discussed are: combination-matching problems in the layout design of minilaser rangefinder, design and testing of a cube-corner arraymore » for laser ranging, mode and far-field pattern of diode laser-phased arrays, new glasses for optics and optoelectronics, optical properties of Li-doped ZnO films, application and machining of Zerodur for optical purposes, finish machining of optical components in mass production.« less

Refraction corrections for surveying

NASA Technical Reports Server (NTRS)

Lear, W. M.

1979-01-01

Optical measurements of range and elevation angle are distorted by the earth's atmosphere. High precision refraction correction equations are presented which are ideally suited for surveying because their inputs are optically measured range and optically measured elevation angle. The outputs are true straight line range and true geometric elevation angle. The 'short distances' used in surveying allow the calculations of true range and true elevation angle to be quickly made using a programmable pocket calculator. Topics covered include the spherical form of Snell's Law; ray path equations; and integrating the equations. Short-, medium-, and long-range refraction corrections are presented in tables.

Gradient forces on double-negative particles in optical tweezers using Bessel beams in the ray optics regime.

PubMed

Ambrosio, Leonardo A; Hernández-Figueroa, Hugo E

2010-11-08

Gradient forces on double negative (DNG) spherical dielectric particles are theoretically evaluated for v-th Bessel beams supposing geometrical optics approximations based on momentum transfer. For the first time in the literature, comparisons between these forces for double positive (DPS) and DNG particles are reported. We conclude that, contrary to the conventional case of positive refractive index, the gradient forces acting on a DNG particle may not reverse sign when the relative refractive index n goes from |n|>1 to |n|<1, thus revealing new and interesting trapping properties.

The contributions of Otto Scherzer (1909-1982) to the development of the electron microscope.

PubMed

Marko, Michael; Rose, Harald

2010-08-01

Otto Scherzer was one of the pioneers of theoretical electron optics. He was coauthor of the first comprehensive book on electron optics and was the first to understand that round electron lenses could not be combined to correct aberrations, as is the case in light optics. He subsequently was the first to describe several alternative means to correct spherical and chromatic aberration of electron lenses. These ideas were put into practice by his laboratory and students at Darmstadt and their successors, leading to the fully corrected electron microscopes now in operation.

Structure and physics of solar faculae

NASA Astrophysics Data System (ADS)

Pecker, J.-C.; Dumont, S.; Mouradian, Z.

1992-04-01

The optical depths of layers in the chromosphere-corona transition (CCT) zone, which is responsible for resolved structures in CII, CIII, OIV, and OVI lines, were determined using a new method that takes into account the effect of roughness (or local departures from sphericity) of the emitting layers in the CCT zone. The method allows determination of the angle alpha typical of the roughness (in case of availability of resolved data) and the two optical depths tau-1 and tau-2. It is shown that, even in unresolved cases, the new method gives a more realistic determination of the optical depths than previously determined.

Electron and positron interaction with pyrimidine: A theoretical investigation

NASA Astrophysics Data System (ADS)

Sinha, Nidhi; Antony, Bobby

2018-03-01

Pyrimidine (C4H4N2) is considered as the building block of nucleobases, viz., cytosine, thymine and uracil. They provide a blueprint for probing the scattering of radiation by DNA and RNA bases. In this article, we report the elastic and total scattering cross-sections for electron and positron scattering from the pyrimidine molecule, employing a spherical complex optical potential (SCOP) formalism for an extensive energy range of 10 eV to 5 keV. In the case of positron scattering, the original SCOP formalism is modified to adequately solve the positron-target dynamics. Moreover, a reasonable agreement is observed between the present results and other available datasets, for both electron and positron scattering. The cross-sections for electron and positron impact scattering by pyrimidine are necessary input data for codes that seek to simulate radiation damage, and hence are useful to model biomolecular systems.

Improved Electrostatic Optical System

NASA Technical Reports Server (NTRS)

Lewis, B. F.

1984-01-01

Device suitable for molecular epitaxial formation of semiconductor components. Improved electrostatic lens system uses cylindrical mirror as central element between two tubular lenses. Abberations introduced by mirror tend to cancel those introduced by tubular lenses. Result is order-of-magnitude improvement in chromatic or spherical compensation.

Optical Model and Cross Section Uncertainties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herman,M.W.; Pigni, M.T.; Dietrich, F.S.

2009-10-05

Distinct minima and maxima in the neutron total cross section uncertainties were observed in model calculations using spherical optical potential. We found this oscillating structure to be a general feature of quantum mechanical wave scattering. Specifically, we analyzed neutron interaction with 56Fe from 1 keV up to 65 MeV, and investigated physical origin of the minima.We discuss their potential importance for practical applications as well as the implications for the uncertainties in total and absorption cross sections.

Graded-index optical dimer formed by optical force

DOE PAGES

Akbarzadeh, Alireza; Koschny, Thomas; Kafesaki, Maria; ...

2016-05-30

We propose an optical dimer formed from two spherical lenses bound by the pressure that light exerts on matter. With the help of the method of force tracing, we find the required graded-index profiles of the lenses for the existence of the dimer. We study the dynamics of the opto-mechanical interaction of lenses under the illumination of collimated light beams and quantitatively validate the performance of the proposed dimer. We also examine the stability of the dimer due to the lateral misalignments and we show how restoring forces bring the dimer into lateral equilibrium. The dimer can be employed inmore » various practical applications such as optical manipulation, sensing and imaging.« less

Graded-index optical dimer formed by optical force

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akbarzadeh, Alireza; Koschny, Thomas; Kafesaki, Maria

We propose an optical dimer formed from two spherical lenses bound by the pressure that light exerts on matter. With the help of the method of force tracing, we find the required graded-index profiles of the lenses for the existence of the dimer. We study the dynamics of the opto-mechanical interaction of lenses under the illumination of collimated light beams and quantitatively validate the performance of the proposed dimer. We also examine the stability of the dimer due to the lateral misalignments and we show how restoring forces bring the dimer into lateral equilibrium. The dimer can be employed inmore » various practical applications such as optical manipulation, sensing and imaging.« less

Pedestal substrate for coated optics

DOEpatents

Hale, Layton C.; Malsbury, Terry N.; Patterson, Steven R.

2001-01-01

A pedestal optical substrate that simultaneously provides high substrate dynamic stiffness, provides low surface figure sensitivity to mechanical mounting hardware inputs, and constrains surface figure changes caused by optical coatings to be primarily spherical in nature. The pedestal optical substrate includes a disk-like optic or substrate section having a top surface that is coated, a disk-like base section that provides location at which the substrate can be mounted, and a connecting cylindrical section between the base and optics or substrate sections. The connecting cylindrical section may be attached via three spaced legs or members. However, the pedestal optical substrate can be manufactured from a solid piece of material to form a monolith, thus avoiding joints between the sections, or the disk-like base can be formed separately and connected to the connecting section. By way of example, the pedestal optical substrate may be utilized in the fabrication of optics for an extreme ultraviolet (EUV) lithography imaging system, or in any optical system requiring coated optics and substrates with reduced sensitivity to mechanical mounts.

Crystalline lens paradoxes revisited: significance of age-related restructuring of the GRIN.

PubMed

Sheil, Conor J; Goncharov, Alexander V

2017-09-01

The accommodating volume-constant age-dependent optical (AVOCADO) model of the crystalline lens is used to explore the age-related changes in ocular power and spherical aberration. The additional parameter m in the GRIN lens model allows decoupling of the axial and radial GRIN profiles, and is used to stabilise the age-related change in ocular power. Data for age-related changes in ocular geometry and lens parameter P in the axial GRIN profile were taken from published experimental data. In our age-dependent eye model, the ocular refractive power shows behaviour similar to the previously unexplained "lens paradox". Furthermore, ocular spherical aberration agrees with the data average, in contrast to the proposed "spherical aberration paradox". The additional flexibility afforded by parameter m , which controls the ratio of the axial and radial GRIN profile exponents, has allowed us to study the restructuring of the lens GRIN medium with age, resulting in a new interpretation of the origin of the power and spherical aberration paradoxes. Our findings also contradict the conceptual idea that the ageing eye is similar to the accommodating eye.

Refraction and the axial length of the eyeball in patients with the optic disc drusen.

PubMed

Obuchowska, Iwona; Mariak, Zofia

2009-01-01

The aim of the study was to demonstrate the relationship between the optic disc drusen (ODD) and the axial length of the eyeball as well as refractive error. We examined prospectively 40 patients with ODD, 18 men and 22 women, age range from 34 to 69 years. All subjects underwent full ophthalmic examination, visual field testing and color-coded duplex sonography of the ocular vessels. Refraction was determined with an autorefractometer (Topcon RM-8000B) and further refined subjectively. Spherical equivalent refraction was calculated as the spherical dioptre plus one half of the cylindrical dioptre. Axial lengths were measured with a Sonomed ultrasound scanner model E-Z Scan AB5500. Clinical signs were observed in 65% of the eyes with drusen, among them, 38% had symptoms of visual acuity loss and all had visual fields defects. There were 21 eyes (18 eyes with and 3 without drusen), with a recorded refractive error. Significant differences in hyperopia were observed between the eyes with and without drusen (p = 0.048). The rate of occurrence of myopia did not differ significantly between affected and unaffected eyes (p = 0.06). The mean spherical equivalent refraction and axial dimensions of the eye differed significantly among the groups of eyes with and without drusen (p < 0.05). Significant differences in mean values of peak-systolic and end-diastolic velocities (p < 0.001) as well as in the resistivity index (p = 0.047) were observed between eyes with and without drusen. The optic disc drusen are often associated with shorter and hyperopic eyes. This anatomical conditions and vascular factors may contribute to pathogenesis of drusen.

Accommodation and age-dependent eye model based on in vivo measurements.

PubMed

Zapata-Díaz, Juan F; Radhakrishnan, Hema; Charman, W Neil; López-Gil, Norberto

2018-03-21

To develop a flexible model of the average eye that incorporates changes with age and accommodation in all optical parameters, including entrance pupil diameter, under photopic, natural, environmental conditions. We collated retrospective in vivo measurements of all optical parameters, including entrance pupil diameter. Ray-tracing was used to calculate the wavefront aberrations of the eye model as a function of age, stimulus vergence and pupil diameter. These aberrations were used to calculate objective refraction using paraxial curvature matching. This was also done for several stimulus positions to calculate the accommodation response/stimulus curve. The model predicts a hyperopic change in distance refraction as the eye ages (+0.22D every 10 years) between 20 and 65 years. The slope of the accommodation response/stimulus curve was 0.72 for a 25 years-old subject, with little change between 20 and 45 years. A trend to a more negative value of primary spherical aberration as the eye accommodates is predicted for all ages (20-50 years). When accommodation is relaxed, a slight increase in primary spherical aberration (0.008μm every 10 years) between 20 and 65 years is predicted, for an age-dependent entrance pupil diameter ranging between 3.58mm (20 years) and 3.05mm (65 years). Results match reasonably well with studies performed in real eyes, except that spherical aberration is systematically slightly negative as compared with the practical data. The proposed eye model is able to predict changes in objective refraction and accommodation response. It has the potential to be a useful design and testing tool for devices (e.g. intraocular lenses or contact lenses) designed to correct the eye's optical errors. Copyright © 2018 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

ComPAQS: a compact concentric UV/visible spectrometer, providing a new tool for air quality monitoring from space

NASA Astrophysics Data System (ADS)

Leigh, Roland J.; Whyte, C.; Cutter, M. A.; Lobb, D. R.; Monks, P. S.

2017-11-01

Under the first phase of the Centre for Earth Observation Instrumentation (CEOI), a breadboard demonstrator of a novel UV/VIS spectrometer has been developed. Using designs from Surrey Satellite Technology Ltd (SSTL) the demonstrator has been constructed and tested at the University of Leicester's Space Research Centre. This spectrometer provides an exceptionally compact instrument for differential optical absorption spectroscopy (DOAS) applications from LEO, GEO, HAP or ground-based platforms. Measurement of atmo spheric compounds with climate change or air quality implications is a key driver for the ground and space-based Earth Observation communities. Techniques using UV/VIS spectroscopy such as DOAS provide measurements of ozone profiles, aerosol optical depth, certain Volatile Organic Compounds, halogenated species, and key air quality parameters including tropospheric nitrogen dioxide. Compact instruments providing the necessary optical performance and spectral resolution are therefore a key enabling technology. The Compact Air Quality Spectrometer (CompAQS) features a concentric arrangement of a spherical meniscus lens, a concave spherical mirror and a suitable curved diffraction grating. This compact design provides efficiency and performance benefits over traditional concepts, improving the precision and spatial resolution available from space borne instruments with limited weight and size budgets. The breadboard spectrometer currently operating at the University of Leicester offers high throughput with a spectral range from 310 to 450 nm at 0.5nm(UV) to 1.0nm (visible) resolution, suitable for DOAS applications. The concentric design is capable of handling high relative apertures, owing to spherical aberration and coma being near zero at all surfaces. The design also provides correction for transverse chromatic aberration and distortion, in addition to correcting for the distortion called `smile' - the curvature of the slit image formed at each wavelength. These properties render this design capable of superior spectral and spatial performance with size and weight budgets significantly lower than standard configurations. In this presentation, the design of the spectrometer is detailed, with results from instrument characterisations undertaken at the University of Leicester, including demonstrations of DOAS fits for key air quality species.

New definition of complexity for self-gravitating fluid distributions: The spherically symmetric, static case

NASA Astrophysics Data System (ADS)

Herrera, L.

2018-02-01

We put forward a new definition of complexity, for static and spherically symmetric self-gravitating systems, based on a quantity, hereafter referred to as complexity factor, that appears in the orthogonal splitting of the Riemann tensor, in the context of general relativity. We start by assuming that the homogeneous (in the energy density) fluid, with isotropic pressure is endowed with minimal complexity. For this kind of fluid distribution, the value of complexity factor is zero. So, the rationale behind our proposal for the definition of complexity factor stems from the fact that it measures the departure, in the value of the active gravitational mass (Tolman mass), with respect to its value for a zero complexity system. Such departure is produced by a specific combination of energy density inhomogeneity and pressure anisotropy. Thus, zero complexity factor may also be found in self-gravitating systems with inhomogeneous energy density and anisotropic pressure, provided the effects of these two factors, on the complexity factor, cancel each other. Some exact interior solutions to the Einstein equations satisfying the zero complexity criterium are found, and prospective applications of this newly defined concept, to the study of the structure and evolution of compact objects, are discussed.

Wave aberrations in rhesus monkeys with vision-induced ametropias

PubMed Central

Ramamirtham, Ramkumar; Kee, Chea-su; Hung, Li-Fang; Qiao-Grider, Ying; Huang, Juan; Roorda, Austin; Smith, Earl L.

2007-01-01

The purpose of this study was to investigate the relationship between refractive errors and high-order aberrations in infant rhesus monkeys. Specifically, we compared the monochromatic wave aberrations measured with a Shack-Hartman wavefront sensor between normal monkeys and monkeys with vision-induced refractive errors. Shortly after birth, both normal monkeys and treated monkeys reared with optically induced defocus or form deprivation showed a decrease in the magnitude of high-order aberrations with age. However, the decrease in aberrations was typically smaller in the treated animals. Thus, at the end of the lens-rearing period, higher than normal amounts of aberrations were observed in treated eyes, both hyperopic and myopic eyes and treated eyes that developed astigmatism, but not spherical ametropias. The total RMS wavefront error increased with the degree of spherical refractive error, but was not correlated with the degree of astigmatism. Both myopic and hyperopic treated eyes showed elevated amounts of coma and trefoil and the degree of trefoil increased with the degree of spherical ametropia. Myopic eyes also exhibited a much higher prevalence of positive spherical aberration than normal or treated hyperopic eyes. Following the onset of unrestricted vision, the amount of high-order aberrations decreased in the treated monkeys that also recovered from the experimentally induced refractive errors. Our results demonstrate that high-order aberrations are influenced by visual experience in young primates and that the increase in high-order aberrations in our treated monkeys appears to be an optical byproduct of the vision-induced alterations in ocular growth that underlie changes in refractive error. The results from our study suggest that the higher amounts of wave aberrations observed in ametropic humans are likely to be a consequence, rather than a cause, of abnormal refractive development. PMID:17825347

Correlation of spectral domain optical coherence tomography findings in sub-silicone oil foveal depression space and visual outcome in eyes undergoing silicone oil removal

PubMed Central

Nagpal, Manish; Bhatt, Kalyani J.; Jain, Pravin; Taleb, Eman Abo; Goswami, Sangeeta; Verma, Amrita

2016-01-01

Background/Purpose: To describe small hyper-reflective spherical bodies in sub-silicone oil-foveal depression (SSO-FD) space using spectral domain optical coherence tomography (SD-OCT) and its effect on visual outcomes in eyes undergoing silicone oil removal (SOR). Methods: This was a prospective interventional comparative study comprising 42 eyes undergoing SOR with clear media. All patients underwent detailed clinical examination and SD-OCT scan of fovea pre-operatively and at 30 days and 90 days postoperatively. Patients were divided into Group A (n = 21) and Group B (n = 21) depending on presence or absence, respectively, of small hyper-reflective spherical bodies in the SSO-FD space in preoperative scans. The findings between SD-OCT and best-corrected visual acuity were correlated and analyzed. Results: The mean age of patients was 41.9 years (range, 23–60 years) in Group A and 45.6 years (range, 23–60 years) in Group B. Twenty-one eyes showed small hyper-reflective spherical bodies on SD-OCT imaging. These were thought to represent emulsified silicone oil globules trapped in the potential space created by silicone oil meniscus and foveal pit, which is the SSO-FD space. These bodies were absent in all post SOR scans of Group A and Group B. Group A had significant visual improvement (p = 0.0001) after SOR with clearance of these hyper-reflective bodies as compared to Group B(p = 0.356). Conclusion: We conclude that these small hyper-reflective spherical bodies in the SSO-FD space were most likely emulsified silicone oil globules and correlated with significant visual improvement with their clearance after silicone oil removal. PMID:29018705

High-precision MoSi multilayer coatings for radial and 2D designs on curved optics

NASA Astrophysics Data System (ADS)

Kriese, Michael D.; Li, Yang; Platonov, Yuriy Y.

2017-10-01

The development of industrial infrastructure for EUV lithography requires a wide array of optics beyond the mask and the scanner optics, which include optics for critical instruments such as exposure testing and actinic inspection. This paper will detail recent results in the production of a variety of high-precision multilayer coatings achieved to support this development. It is critical that the optical designs factor in the capabilities of the achievable multilayer gradients and the associated achievable precision, including impact to surface distortion from the added figure error of the multilayer coating, which adds additional requirements of a specific shape to the period distribution. For example, two different coatings may achieve a ±0.2% variation in multilayer period, but have considerably different added figure error. Part I of the paper will focus on radially-symmetric spherical and aspherical optics. Typical azimuthal uniformity (variation at a fixed radius) achieved is less than ±0.005nm total variation, including measurement precision, on concave optics up to 200mm diameter. For highly curved convex optics (radius of curvature less than 50mm), precision is more challenging and the total variation increases to ±0.01nm total variation for optics 10-30mm in diameter. Total added figure error achieved has been as low as 0.05nm. Part II of the paper will focus on multilayer designs graded in two directions, rather than radially, in order to accommodate the increased complexity of elliptical, toroidal and hyperbolic surfaces. In most cases, the symmetry of the required multilayer gradient does not match the symmetry of the optical surface, and this interaction must be countered via the process design. Achieving such results requires additional flexibility in the design of the deposition equipment, and will be discussed with several examples in the paper, such as the use of variable velocity of an inline substrate carrier in conjunction with a shaped target aperture to produce ±0.03nm total variation on an off-axis elliptical surface.

Automated retinofugal visual pathway reconstruction with multi-shell HARDI and FOD-based analysis.

PubMed

Kammen, Alexandra; Law, Meng; Tjan, Bosco S; Toga, Arthur W; Shi, Yonggang

2016-01-15

Diffusion MRI tractography provides a non-invasive modality to examine the human retinofugal projection, which consists of the optic nerves, optic chiasm, optic tracts, the lateral geniculate nuclei (LGN) and the optic radiations. However, the pathway has several anatomic features that make it particularly challenging to study with tractography, including its location near blood vessels and bone-air interface at the base of the cerebrum, crossing fibers at the chiasm, somewhat-tortuous course around the temporal horn via Meyer's Loop, and multiple closely neighboring fiber bundles. To date, these unique complexities of the visual pathway have impeded the development of a robust and automated reconstruction method using tractography. To overcome these challenges, we develop a novel, fully automated system to reconstruct the retinofugal visual pathway from high-resolution diffusion imaging data. Using multi-shell, high angular resolution diffusion imaging (HARDI) data, we reconstruct precise fiber orientation distributions (FODs) with high order spherical harmonics (SPHARM) to resolve fiber crossings, which allows the tractography algorithm to successfully navigate the complicated anatomy surrounding the retinofugal pathway. We also develop automated algorithms for the identification of ROIs used for fiber bundle reconstruction. In particular, we develop a novel approach to extract the LGN region of interest (ROI) based on intrinsic shape analysis of a fiber bundle computed from a seed region at the optic chiasm to a target at the primary visual cortex. By combining automatically identified ROIs and FOD-based tractography, we obtain a fully automated system to compute the main components of the retinofugal pathway, including the optic tract and the optic radiation. We apply our method to the multi-shell HARDI data of 215 subjects from the Human Connectome Project (HCP). Through comparisons with post-mortem dissection measurements, we demonstrate the retinotopic organization of the optic radiation including a successful reconstruction of Meyer's loop. Then, using the reconstructed optic radiation bundle from the HCP cohort, we construct a probabilistic atlas and demonstrate its consistency with a post-mortem atlas. Finally, we generate a shape-based representation of the optic radiation for morphometry analysis. Copyright © 2015 Elsevier Inc. All rights reserved.

Stress Measurement by Geometrical Optics

NASA Technical Reports Server (NTRS)

Robinson, R. S.; Rossnagel, S. M.

1986-01-01

Fast, simple technique measures stresses in thin films. Sample disk bowed by stress into approximately spherical shape. Reflected image of disk magnified by amount related to curvature and, therefore, stress. Method requires sample substrate, such as cheap microscope cover slide, two mirrors, laser light beam, and screen.

The Hubble Space Telescope: Problems and Solutions.

ERIC Educational Resources Information Center

Villard, Ray

1990-01-01

Presented is the best understanding of the flaw discovered in the optics of the Hubble Space Telescope and the possible solutions to the problems. The spherical aberration in the telescope's mirror and its effect on the quality of the telescope's imaging ability is discussed. (CW)

Linearized T-Matrix and Mie Scattering Computations

NASA Technical Reports Server (NTRS)

Spurr, R.; Wang, J.; Zeng, J.; Mishchenko, M. I.

2011-01-01

We present a new linearization of T-Matrix and Mie computations for light scattering by non-spherical and spherical particles, respectively. In addition to the usual extinction and scattering cross-sections and the scattering matrix outputs, the linearized models will generate analytical derivatives of these optical properties with respect to the real and imaginary parts of the particle refractive index, and (for non-spherical scatterers) with respect to the ''shape'' parameter (the spheroid aspect ratio, cylinder diameter/height ratio, Chebyshev particle deformation factor). These derivatives are based on the essential linearity of Maxwell's theory. Analytical derivatives are also available for polydisperse particle size distribution parameters such as the mode radius. The T-matrix formulation is based on the NASA Goddard Institute for Space Studies FORTRAN 77 code developed in the 1990s. The linearized scattering codes presented here are in FORTRAN 90 and will be made publicly available.

Three-dimensional ghost imaging using acoustic transducer

NASA Astrophysics Data System (ADS)

Zhang, Chi; Guo, Shuxu; Guan, Jian; Cao, Junsheng; Gao, Fengli

2016-06-01

We propose a novel three-dimensional (3D) ghost imaging method using unfocused ultrasonic transducer, where the transducer is used as the bucket detector to collect the total photoacoustic signal intensity from spherical surfaces with different radius circling the transducer. This collected signal is a time sequence corresponding to the optic absorption information on the spherical surfaces, and the values at the same moments in all the sequences are used as the bucket signals to restore the corresponding spherical images, which are assembled as the object 3D reconstruction. Numerical experiments show this method can effectively accomplish the 3D reconstruction and by adding up each sequence on time domain as a bucket signal it can also realize two dimensional (2D) ghost imaging. The influence of the measurement times on the 3D and 2D reconstruction is analyzed with Peak Signal to Noise Ratio (PSNR) as the yardstick, and the transducer as a bucket detector is also discussed.

Dual-phase-shift spherical Fizeau interferometer for reduction of noise due to internally scattered light

NASA Astrophysics Data System (ADS)

Kumagai, Toshiki; Hibino, Kenichi; Nagaike, Yasunari

2017-03-01

Internally scattered light in a Fizeau interferometer is generated from dust, defects, imperfect coating of the optical components, and multiple reflections inside the collimator lens. It produces additional noise fringes in the observed interference image and degrades the repeatability of the phase measurement. A method to reduce the phase measurement error is proposed, in which the test surface is mechanically translated between each phase measurement in addition to an ordinary phase shift of the reference surface. It is shown that a linear combination of several measured phases at different test surface positions can reduce the phase errors caused by the scattered light. The combination can also compensate for the nonuniformity of the phase shift that occurs in spherical tests. A symmetric sampling of the phase measurements can cancel the additional primary spherical aberrations that occur when the test surface is out of the null position of the confocal configuration.

Wide-angle flat field telescope

NASA Technical Reports Server (NTRS)

Hallam, K. L.; Howell, B. J.; Wilson, M. E.

1986-01-01

Described is an unobscured three mirror wide angle telescopic imaging system comprised of an input baffle which provides a 20 deg (Y axis) x 30 deg (X axis) field of view, a primary mirror having a convex spherical surface, a secondary mirror having a concave ellipsoidal reflecting surface, a tertiary mirror having a concave spherical reflecting surface. The mirrors comprise mirror elements which are offset segments of parent mirrors whose axes and vertices commonly lie on the system's optical axis. An iris diaphragm forming an aperture stop is located between the secondary and tertiary mirror with its center also being coincident with the optical axis and being further located at the beam waist of input light beams reflected from the primary and secondary mirror surfaces. At the system focus following the tertiary mirror is located a flat detector which may be, for example, a TV imaging tube or a photographic film. When desirable, a spectral transmission filter is placed in front of the detector in close proximity thereto.

PHOTOPHORESIS IN A DILUTE, OPTICALLY THICK MEDIUM AND DUST MOTION IN PROTOPLANETARY DISKS

DOE Office of Scientific and Technical Information (OSTI.GOV)

McNally, Colin P.; Hubbard, Alexander, E-mail: cmcnally@nbi.dk, E-mail: ahubbard@amnh.org

2015-11-20

We derive expressions for the photophoretic force on opaque spherical particles in a dilute gas in the optically thick regime where the radiation field is in local thermal equilibrium. Under those conditions, the radiation field has a simple form, leading to well defined analytical approximations for the photophoretic force that also consider both the internal thermal conduction within the particle, and the effects of heat conduction and radiation to the surrounding gas. We derive these results for homogeneous spherical particles; and for the double layered spheres appropriate for modeling solid grains with porous aggregate mantles. Then, as a specific astrophysicalmore » application of these general physical results, we explore the parameter space relevant to the photophoresis driven drift of dust in protoplanetary disks. We show that highly porous silicate grains have sufficiently low thermal conductivities that photophoretic effects, such as significant relative velocities between particles with differing porosity or levitation above the midplane, are expected to occur.« less

High-precision double-frequency interferometric measurement of the cornea shape

NASA Astrophysics Data System (ADS)

Molebny, Vasyl V.; Pallikaris, Ioannis G.; Naoumidis, Leonidas P.; Smirnov, Eugene M.; Ilchenko, Leonid M.; Goncharov, Vadym O.

1996-11-01

To measure the shape of the cornea and its declinations from the necessary values before and after PRK operation, s well as the shape of other spherical objects like artificial pupil, a technique was used of double-frequency dual-beam interferometry. The technique is based on determination of the optical path difference between two neighboring laser beams, reflected from the cornea or other surface under investigation. Knowing the distance between the beams on the investigated shape. The shape itself is reconstructed by along-line integration. To adjust the wavefront orientation of the laser beam to the spherical shape of the cornea or artificial pupil in the course of scanning, additional lens is involved. Signal-to-noise ratio is ameliorated excluding losses in the acousto-optic deflectors. Polarization selection is realized for choosing the signal needed for measurement. 2D image presentation is accompanied by convenient PC accessories, permitting precise cross-section measurements along selected directions. Sensitivity of the order of 10-2 micrometers is achieved.

Manufacturing and coating of optical components for the EnMAP hyperspectral imager

NASA Astrophysics Data System (ADS)

Schürmann, M.; Gäbler, D.; Schlegel, R.; Schwinde, S.; Peschel, T.; Damm, C.; Jende, R.; Kinast, J.; Müller, S.; Beier, M.; Risse, S.; Sang, B.; Glier, M.; Bittner, H.; Erhard, M.

2016-07-01

The optical system of the hyperspectral imager of the Environmental Mapping and Analysis Program (EnMAP) consists of a three-mirror anastigmat (TMA) and two independent spectrometers working in the VNIR and SWIR spectral range, respectively. The VNIR spectrometer includes a spherical NiP coated Al6061 mirror that has been ultra-precisely diamond turned and finally coated with protected silver as well as four curved fused silica (FS) and flint glass (SF6) prisms, respectively, each with broadband antireflection (AR) coating, while the backs of the two outer prisms are coated with a high-reflective coating. For AR coating, plasma ion assisted deposition (PIAD) has been used; the high-reflective enhanced Ag-coating on the backside has been deposited by magnetron sputtering. The SWIR spectrometer contains four plane and spherical gold-coated mirrors, respectively, and two curved FS prisms with a broadband antireflection coating. Details about the ultra-precise manufacturing of metal mirrors and prisms as well as their coating are presented in this work.

Modeling the Deep Impact Near-nucleus Observations of H2O and CO2 in Comet 9P/Tempel 1 Using Asymmetric Spherical Coupled Escape Probability

NASA Astrophysics Data System (ADS)

Gersch, Alan M.; A’Hearn, Michael F.; Feaga, Lori M.

2018-04-01

We have applied our asymmetric spherical adaptation of Coupled Escape Probability to the modeling of optically thick cometary comae. Expanding on our previously published work, here we present models including asymmetric comae. Near-nucleus observations from the Deep Impact mission have been modeled, including observed coma morphology features. We present results for two primary volatile species of interest, H2O and CO2, for comet 9P/Tempel 1. Production rates calculated using our best-fit models are notably greater than those derived from the Deep Impact data based on the assumption of optically thin conditions, both for H2O and CO2 but more so for CO2, and fall between the Deep Impact values and the global pre-impact production rates measured at other observatories and published by Schleicher et al. (2006), Mumma et al. (2005), and Mäkinen et al. (2007).

Design of refractive fore-optics with wide field of view and waveband for miniature imaging spectrometer

NASA Astrophysics Data System (ADS)

Mao, Jingchao; Xu, Minyi; Liu, Qinghan; Shen, Weimin

2016-10-01

With the development of unmanned airborne vehicle (UAV) remote sensing technology, miniature high-resolution imaging spectrometers are greatly needed. In order to improve remote sensing efficiency and get wider coverage, it's urgent to design and develop fore-optics with wide field of view and waveband for imaging spectrometer. As the refractive system has no central obscuration and it's conducive to manufacture and assemble, so it's used for our fore-optics. The key is the correction of secondary spectrum of systems working in broad waveband and meeting the requirement of imagery telecentricity to be appropriate for linear pushbroom imaging system. Suitable glasses are selected on the Glass Map, from where each glass has an Abbe number υd and Partial Dispersion. Based on the theory of Gaussian Optics and Seidel third-order aberration theory, the paper derives apochromatic formula, and the power of individual lenses can be calculated. Then with a required value of spherical aberration and coma, this paper derives equations to calculate the initial structure of apochromatic optical systems. Finally, optimized refractive SWIR fore-optics working in 1μm-2.5μm with effective focal length (EFFL) of 11mm is reported. Its full field and F-number are respectively 40°, F/2.8. The system has many advantages such as simple and compact structure, small size, near diffraction-limited imaging quality, small secondary spectrum and imagery telecentricity. Especially it consists of spherical surfaces that can greatly reduce the difficulty and the cost of manufacture as well as test, which is applicable for SWIR imaging spectrometer with wide field of view.

Fabrication of polymer microlenses on single mode optical fibers for light coupling

NASA Astrophysics Data System (ADS)

Zaboub, Monsef; Guessoum, Assia; Demagh, Nacer-Eddine; Guermat, Abdelhak

2016-05-01

In this paper, we present a technique for producing fibers optics micro-collimators composed of polydimethylsiloxane PDMS microlenses of different radii of curvature. The waist and working distance values obtained enable the optimization of optical coupling between optical fibers, fibers and optical sources, and fibers and detectors. The principal is based on the injection of polydimethylsiloxane (PDMS) into a conical micro-cavity chemically etched at the end of optical fibers. A spherical microlens is then formed that is self-centered with respect to the axis of the fiber. Typically, an optimal radius of curvature of 10.08 μm is obtained. This optimized micro-collimator is characterized by a working distance of 19.27 μm and a waist equal to 2.28 μm for an SMF 9/125 μm fiber. The simulation and experimental results reveal an optical coupling efficiency that can reach a value of 99.75%.

Tunability and stability of gold nanoparticles obtained from chloroauric acid and sodium thiosulfate reaction

PubMed Central

2012-01-01

In the quest for producing an effective, clinically relevant therapeutic agent, scalability, repeatability, and stability are paramount. In this paper, gold nanoparticles (GNPs) with precisely controlled near-infrared (NIR) absorption are synthesized by a single-step reaction of HAuCl4 and Na2S2O3 without assistance of additional templates, capping reagents, or seeds. The anisotropy in the shape of gold nanoparticles offers high NIR absorption, making it therapeutically relevant. The synthesized products consist of GNPs with different shapes and sizes, including small spherical colloid gold particles and non-spherical gold crystals. The NIR absorption wavelengths and particle size increase with increasing molar ratio of HAuCl4/Na2S2O3. Non-spherical gold particles can be further purified and separated by centrifugation to improve the NIR-absorbing fraction of particles. In-depth studies reveal that GNPs with good structural and optical stability only form in a certain range of the HAuCl4/Na2S2O3 molar ratio, whereas higher molar ratios result in unstable GNPs, which lose their NIR absorption peak due to decomposition and reassembly via Ostwald ripening. Tuning the optical absorption of the gold nanoparticles in the NIR regime via a robust and repeatable method will improve many applications requiring large quantities of desired NIR-absorbing nanoparticles. PMID:22726762

Light scattering by nonspherical particles: Remote sensing and climatic implications

NASA Astrophysics Data System (ADS)

Liou, K. N.; Takano, Y.

Calculations of the scattering and adsorption properties of ice crystals and aerosols, which are usually nonspherical, require specific methodologies. There is no unique theoretical solution for the scattering by nonspherical particles. Practically, all the numerical solutions for the scattering of nonspherical particles, including the exact wave equation approach, integral equation method, and discrete-dipole approximation, are applicable only to size parameters less than about 20. Thus, these methods are useful for the study of radiation problems involving nonspherical aerosols and small ice crystals in the thermal infrared wavelengths. The geometric optics approximation has been used to evaluate the scattering, absorption and polarization properties of hexagonal ice crystals whose sizes are much larger than the incident wavelength. This approximation is generally valid for hexagonal ice crystals with size parameters larger than about 30. From existing laboratory data and theoretical results, we illustrate that nonspherical particles absorb less and have a smaller asymmetry factor than the equal-projected area/volume spherical counterparts. In particular, we show that hexagonal ice crystals exhibit numerous halo and arc features that cannot be obtained from spherical particles; and that ice crystals scatter more light in the 60° to 140° scattering angle regions than the spherical counterparts. Satellite remote sensing of the optical depth and height of cirrus clouds using visible and IR channels must use appropriate phase functions for ice crystals. Use of an equivalent sphere model would lead to a significant overestimation and underestimation of the cirrus optical depth and height, respectively. Interpretation of the measurements for polarization reflected from sunlight involving cirrus clouds cannot be made without an appropriate ice crystal model. Large deviations exist for the polarization patterns between spheres and hexagonal ice crystals. Interpretation of lidar backscattering and depolarization signals must also utilize the scattering characteristics of hexagonal ice crystals. Equivalent spherical models substantially underestimate the broadband solar albedos of ice crystal clouds because of stronger forward scattering and larger absorption by spherical particles than hexagonal ice crystals. We illustrate that the net cloud radiative forcing at the top of the atmosphere involving most cirrus clouds is positive, implying that the IR greenhouse effect outweighs the solar albedo effect. If the radiative properties of equivalent spheres are used, a significant increase in cloud radiative forcing occurs. Using a one-dimensional cloud and climate model, we further demonstrate that there is sufficient model sensitivity, in terms of temperature increase, to the use of ice crystal models in radiation calculations.

Calculation of far-field scattering from nonspherical particles using a geometrical optics approach

NASA Technical Reports Server (NTRS)

Hovenac, Edward A.

1991-01-01

A numerical method was developed using geometrical optics to predict far-field optical scattering from particles that are symmetric about the optic axis. The diffractive component of scattering is calculated and combined with the reflective and refractive components to give the total scattering pattern. The phase terms of the scattered light are calculated as well. Verification of the method was achieved by assuming a spherical particle and comparing the results to Mie scattering theory. Agreement with the Mie theory was excellent in the forward-scattering direction. However, small-amplitude oscillations near the rainbow regions were not observed using the numerical method. Numerical data from spheroidal particles and hemispherical particles are also presented. The use of hemispherical particles as a calibration standard for intensity-type optical particle-sizing instruments is discussed.

Magnetic and Optical Properties of Submicron-Size Hollow Spheres

PubMed Central

Ye, Quan-Lin; Yoshikawa, Hirofumi; Awaga, Kunio

2010-01-01

Magnetic hollow spheres with a controlled diameter and shell thickness have emerged as an important class of magnetic nanomaterials. The confined hollow geometry and pronouncedly curved surfaces induce unique physical properties different from those of flat thin films and solid counterparts. In this paper, we focus on recent progress on submicron-size spherical hollow magnets (e.g., cobalt- and iron-based materials), and discuss the effects of the hollow shape and the submicron size on magnetic and optical properties.

Intersubband optical absorption between multi energy levels of electrons in InGaN/GaN spherical core-shell quantum dots

NASA Astrophysics Data System (ADS)

Liu, W. H.; Qu, Y.; Ban, S. L.

2017-02-01

The intersubband optical absorption between multi energy levels of electrons in InxGa1-xN/GaN spherical core-shell quantum dots (CSQDs) and ternary mixed crystal and size effects have been investigated by using the principle of density matrix. Electronic eigenstates under the effect of built-in electric field (BEF) have been calculated by a finite element method. The results show that optical absorption between intersubbands with main quantum numbers n = 1 and n = 2 are as important as that between ones with n = 1 and different angular quantum numbers when the BEF is taken into account. In consideration of BEF, the saturation of total optical absorption coefficients (ACs) and secondary peaks of refractive index changes (RICs) appear when incident light intensity I surpasses a certain value. For a given I, the maximum ACs and zero RICs positions in InxGa1-xN/GaN CSQDs with a fixed shell size have a blue-shift when x increases or the core InxGa1-xN radius R1 decreases from 5 nm. However, when R1 > 5 nm, ACs and RICs tend to be stable. The results indicate that effective adjustment of ACs and RICs in CSQDs with BEFs by size is in a limited scale range. The saturation of ACs or secondary peaks of RICs appear more likely in CSQDs with smaller x or larger R1. These results are expected to be helpful both in the further theoretical and experimental study on optic devices consisting of CSQDs.

Radiative transfer in spherical shell atmospheres. II - Asymmetric phase functions

NASA Technical Reports Server (NTRS)

Kattawar, G. W.; Adams, C. N.

1978-01-01

This paper investigates the effects of sphericity on the radiation reflected from a planet with a homogeneous conservative-scattering atmosphere of optical thicknesses of 0.25 and 1.0. A Henyey-Greenstein phase function with asymmetry factors of 0.5 and 0.7 was considered. Significant differences were found when these results were compared with the plane-parallel calculations. Also, large violations of the reciprocity theorem, which is only true for plane-parallel calculations, were noted. Results are presented for the radiance versus height distributions as a function of planetary phase angle. These results will be useful to researchers in the field of remote sensing and planetary spectroscopy.

Cooperative effects in spherical spasers: Ab initio analytical model

NASA Astrophysics Data System (ADS)

Bordo, V. G.

2017-06-01

A fully analytical semiclassical theory of cooperative optical processes which occur in an ensemble of molecules embedded in a spherical core-shell nanoparticle is developed from first principles. Both the plasmonic Dicke effect and spaser generation are investigated for the designs in which a shell/core contains an arbitrarily large number of active molecules in the vicinity of a metallic core/shell. An essential aspect of the theory is an ab initio account of the feedback from the core/shell boundaries which significantly modifies the molecular dynamics. The theory provides rigorous, albeit simple and physically transparent, criteria for both plasmonic superradiance and surface plasmon generation.

Light-weight spherical mirrors for Cherenkov detectors

NASA Astrophysics Data System (ADS)

Cisbani, E.; Colilli, S.; Crateri, R.; Cusanno, F.; Fratoni, R.; Frullani, S.; Garibaldi, F.; Giuliani, F.; Gricia, M.; Iodice, M.; Iommi, R.; Lucentini, M.; Mostarda, A.; Pierangeli, L.; Santavenere, F.; Urciuoli, G. M.; De Leo, R.; Lagamba, L.; Nappi, E.; Braem, A.; Vernin, P.

2003-01-01

Light-weight spherical mirrors have been appositely designed and built for the gas threshold Cherenkov detectors of the two Hall A spectrometers. The mirrors are made of a 1 mm thick aluminized plexiglass sheet, reinforced by a rigid backing consisting of a phenolic honeycomb sandwiched between two carbon fiber mats epoxy glued. The produced mirrors have a thickness equivalent to 0.55% of radiation length, and an optical slope error of about 5.5 mrad. These characteristics make these mirrors suitable for the implementation in Cherenkov threshold detectors. Ways to improve the mirror features are also discussed in view of their possible employment in RICH detectors.

Methods of and apparatus for recording images occurring just prior to a rapid, random event

DOEpatents

Kelley, Edward F.

1994-01-01

An apparatus and a method are disclosed for recording images of events in a medium wherein the images that are recorded are of conditions existing just prior to and during the occurrence of an event that triggers recording of these images. The apparatus and method use an optical delay path that employs a spherical focusing mirror facing a circular array of flat return mirrors around a central flat mirror. The image is reflected in a symmetric pattern which balances astigmatism which is created by the spherical mirror. Delays on the order of hundreds of nanoseconds are possible.

Analytical model for thermal lensing and spherical aberration in diode side-pumped Nd:YAG laser rod having Gaussian pump profile

NASA Astrophysics Data System (ADS)

M, H. Moghtader Dindarlu; M Kavosh, Tehrani; H, Saghafifar; A, Maleki

2015-12-01

In this paper, according to the temperature and strain distribution obtained by considering the Gaussian pump profile and dependence of physical properties on temperature, we derive an analytical model for refractive index variations of the diode side-pumped Nd:YAG laser rod. Then we evaluate this model by numerical solution and our maximum relative errors are 5% and 10% for variations caused by thermo-optical and thermo-mechanical effects; respectively. Finally, we present an analytical model for calculating the focal length of the thermal lens and spherical aberration. This model is evaluated by experimental results.

Spherical Primary Optical Telescope (SPOT) Segment Fabrication

DTIC Science & Technology

2010-06-07

of Pyrex. One mirror (segment) was figured at GSFC and final figured at QED using Magnetorheological Finishing . Two other segments are in process...point) have been cast • Segment 1 was figured at GSFC completed at QED using magnetorheological finishing (MRF) • New GSFC figuring facility brought on

Light Scattering by Marine Particles: Modeling with Non-spherical Shapes

DTIC Science & Technology

2011-09-30

coccoliths detached from Emiliania huxleyi, Limnology and Oceanography, 46, 1438−1454, 2001. Gordon, H.R., T.J. Smyth, W.M. Balch, and G.C. Boynton...Light scattering by coccoliths detached from Emiliania huxleyi, Applied Optics, (2009). PUBLICATIONS H.R. Gordon, Light scattering by randomly

Optical nulling apparatus and method for testing an optical surface

NASA Technical Reports Server (NTRS)

Olczak, Eugene (Inventor); Hannon, John J. (Inventor); Dey, Thomas W. (Inventor); Jensen, Arthur E. (Inventor)

2008-01-01

An optical nulling apparatus for testing an optical surface includes an aspheric mirror having a reflecting surface for imaging light near or onto the optical surface under test, where the aspheric mirror is configured to reduce spherical aberration of the optical surface under test. The apparatus includes a light source for emitting light toward the aspheric mirror, the light source longitudinally aligned with the aspheric mirror and the optical surface under test. The aspheric mirror is disposed between the light source and the optical surface under test, and the emitted light is reflected off the reflecting surface of the aspheric mirror and imaged near or onto the optical surface under test. An optical measuring device is disposed between the light source and the aspheric mirror, where light reflected from the optical surface under test enters the optical measuring device. An imaging mirror is disposed longitudinally between the light source and the aspheric mirror, and the imaging mirror is configured to again reflect light, which is first reflected from the reflecting surface of the aspheric mirror, onto the optical surface under test.

Design and experimental verification for optical module of optical vector-matrix multiplier.

PubMed

Zhu, Weiwei; Zhang, Lei; Lu, Yangyang; Zhou, Ping; Yang, Lin

2013-06-20

Optical computing is a new method to implement signal processing functions. The multiplication between a vector and a matrix is an important arithmetic algorithm in the signal processing domain. The optical vector-matrix multiplier (OVMM) is an optoelectronic system to carry out this operation, which consists of an electronic module and an optical module. In this paper, we propose an optical module for OVMM. To eliminate the cross talk and make full use of the optical elements, an elaborately designed structure that involves spherical lenses and cylindrical lenses is utilized in this optical system. The optical design software package ZEMAX is used to optimize the parameters and simulate the whole system. Finally, experimental data is obtained through experiments to evaluate the overall performance of the system. The results of both simulation and experiment indicate that the system constructed can implement the multiplication between a matrix with dimensions of 16 by 16 and a vector with a dimension of 16 successfully.

A Quantitative Test of the Applicability of Independent Scattering to High Albedo Planetary Regoliths

NASA Technical Reports Server (NTRS)

Goguen, Jay D.

1993-01-01

To test the hypothesis that the independent scattering calculation widely used to model radiative transfer in atmospheres and clouds will give a useful approximation to the intensity and linear polarization of visible light scattered from an optically thick surface of transparent particles, laboratory measurements are compared to the independent scattering calculation for a surface of spherical particles with known optical constants and size distribution. Because the shape, size distribution, and optical constants of the particles are known, the independent scattering calculation is completely determined and the only remaining unknown is the net effect of the close packing of the particles in the laboratory sample surface...

Inorganic optical taggant and method of making

DOEpatents

Lauf, Robert J.; Anderson, Kimberly K.; Montgomery, Frederick C.

2005-05-31

Sintered, translucent ceramic microbeads, preferably alumina, titania, zirconia, yttria, zirconium phosphate, or yttrium aluminum garnet (YAG) are doped with one or more optically active species. The beads may be added to substances such as explosives in order to create a distinctive optical signature that identifies a manufacturer, lot number, etc. in the event of the need for forensic analysis. Because the beads have a generally spherical surface, the radius of curvature provides an additional distinguishing characteristic by which a particular sample may be identified. The beads could also be formulated into paints if needed to create distinctive optical signatures for camouflage, decoys, or other countermeasures and could also be applied as a dust to track the movement of personnel, vehicles, etc.

Fundamentals of negative refractive index optical trapping: forces and radiation pressures exerted by focused Gaussian beams using the generalized Lorenz-Mie theory

PubMed Central

Ambrosio, Leonardo A.; Hernández-Figueroa, Hugo E.

2010-01-01

Based on the generalized Lorenz-Mie theory (GLMT), this paper reveals, for the first time in the literature, the principal characteristics of the optical forces and radiation pressure cross-sections exerted on homogeneous, linear, isotropic and spherical hypothetical negative refractive index (NRI) particles under the influence of focused Gaussian beams in the Mie regime. Starting with ray optics considerations, the analysis is then extended through calculating the Mie coefficients and the beam-shape coefficients for incident focused Gaussian beams. Results reveal new and interesting trapping properties which are not observed for commonly positive refractive index particles and, in this way, new potential applications in biomedical optics can be devised. PMID:21258549

Forming aspheric optics by controlled deposition

DOEpatents

Hawryluk, A.M.

1998-04-28

An aspheric optical element is disclosed formed by depositing material onto a spherical surface of an optical element by controlled deposition to form an aspheric surface of desired shape. A reflecting surface, single or multi-layer, can then be formed on the aspheric surface by evaporative or sputtering techniques. Aspheric optical elements are suitable for deep ultra-violet (UV) and x-ray wavelengths. The reflecting surface may, for example, be a thin ({approx}100 nm) layer of aluminum, or in some cases the deposited modifying layer may function as the reflecting surface. For certain applications, multi-layer reflective surfaces may be utilized, such as chromium-carbon or tungsten-carbon multi-layer, with the number of layers and thickness being determined by the intended application. 4 figs.

Forming aspheric optics by controlled deposition

DOEpatents

Hawryluk, Andrew M.

1998-01-01

An aspheric optical element formed by depositing material onto a spherical surface of an optical element by controlled deposition to form an aspheric surface of desired shape. A reflecting surface, single or multi-layer, can then be formed on the aspheric surface by evaporative or sputtering techniques. Aspheric optical elements are suitable for deep ultra-violet (UV) and x-ray wavelengths. The reflecting surface may, for example, be a thin (.about.100 nm) layer of aluminum, or in some cases the deposited modifying layer may function as the reflecting surface. For certain applications, multi-layer reflective surfaces may be utilized, such as chromium-carbon or tungsten-carbon multi-layer, with the number of layers and thickness being determined by the intended application.

Electrodynamic multiple-scattering method for the simulation of optical trapping atop periodic metamaterials

NASA Astrophysics Data System (ADS)

Yannopapas, Vassilios; Paspalakis, Emmanuel

2018-07-01

We present a new theoretical tool for simulating optical trapping of nanoparticles in the presence of an arbitrary metamaterial design. The method is based on rigorously solving Maxwell's equations for the metamaterial via a hybrid discrete-dipole approximation/multiple-scattering technique and direct calculation of the optical force exerted on the nanoparticle by means of the Maxwell stress tensor. We apply the method to the case of a spherical polystyrene probe trapped within the optical landscape created by illuminating of a plasmonic metamaterial consisting of periodically arranged tapered metallic nanopyramids. The developed technique is ideally suited for general optomechanical calculations involving metamaterial designs and can compete with purely numerical methods such as finite-difference or finite-element schemes.

Fundamentals of negative refractive index optical trapping: forces and radiation pressures exerted by focused Gaussian beams using the generalized Lorenz-Mie theory.

PubMed

Ambrosio, Leonardo A; Hernández-Figueroa, Hugo E

2010-11-04

Based on the generalized Lorenz-Mie theory (GLMT), this paper reveals, for the first time in the literature, the principal characteristics of the optical forces and radiation pressure cross-sections exerted on homogeneous, linear, isotropic and spherical hypothetical negative refractive index (NRI) particles under the influence of focused Gaussian beams in the Mie regime. Starting with ray optics considerations, the analysis is then extended through calculating the Mie coefficients and the beam-shape coefficients for incident focused Gaussian beams. Results reveal new and interesting trapping properties which are not observed for commonly positive refractive index particles and, in this way, new potential applications in biomedical optics can be devised.

Concentrator optical characterization using computer mathematical modelling and point source testing

NASA Technical Reports Server (NTRS)

Dennison, E. W.; John, S. L.; Trentelman, G. F.

1984-01-01

The optical characteristics of a paraboloidal solar concentrator are analyzed using the intercept factor curve (a format for image data) to describe the results of a mathematical model and to represent reduced data from experimental testing. This procedure makes it possible not only to test an assembled concentrator, but also to evaluate single optical panels or to conduct non-solar tests of an assembled concentrator. The use of three-dimensional ray tracing computer programs to calculate the mathematical model is described. These ray tracing programs can include any type of optical configuration from simple paraboloids to array of spherical facets and can be adapted to microcomputers or larger computers, which can graphically display real-time comparison of calculated and measured data.

Role of preoperative cycloplegic refraction in LASIK treatment of hyperopia.

PubMed

Frings, Andreas; Steinberg, Johannes; Druchkiv, Vasyl; Linke, Stephan J; Katz, Toam

2016-07-01

Previous studies have suggested that, to improve refractive predictability in hyperopic LASIK treatments, preoperative cycloplegic or manifest refraction, or a combination of both, could be used in the laser nomogram. We set out to investigate (1) the prevalence of a high difference between manifest and cycloplegic spherical equivalent in hyperopic eyes preoperatively, and (2) the related predictability of postoperative keratometry. Retrospective cross-sectional data analysis of consecutive treated 186 eyes from 186 consecutive hyperopic patients (mean age 42 [±12] years) were analyzed. Excimer ablation for all eyes was performed using a mechanical microkeratome (SBK, Moria, France) and an Allegretto excimer laser platform. Two groups were defined according to the difference between manifest and cycloplegic spherical equivalent which was defined as ≥1.00 diopter (D); the data was analyzed according to refractive outcome in terms of refractive predictability, efficacy, and safety. In 24 eyes (13 %), a preoperative difference of ≥1.00D between manifest spherical equivalent and cycloplegic spherical equivalent (= MCD) occurred. With increasing preoperative MCD, the postoperative achieved spherical equivalent showed hyperopic regression after 3 months. There was no statistically significant effect of age (accommodation) or optical zone size on the achieved spherical equivalent. A difference of ≥1.00D occurs in about 13 % of hyperopia cases. We suggest that hyperopic correction should be based on the manifest spherical equivalent in eyes with preoperative MCD <1.00D. If the preoperative MCD is ≥1.00D, treatment may produce manifest undercorrection, and therefore we advise that the patient should be warrned about lower predictability, and suggest basing conclusions on the arithmetic mean calculated from the preoperative manifest and cycloplegic spheres.

Theranostic nanoshells: from probe design to imaging and treatment of cancer.

PubMed

Bardhan, Rizia; Lal, Surbhi; Joshi, Amit; Halas, Naomi J

2011-10-18

Recent advances in nanoscience and biomedicine have expanded our ability to design and construct multifunctional nanoparticles that combine targeting, therapeutic, and diagnostic functions within a single nanoscale complex. The theranostic capabilities of gold nanoshells, spherical nanoparticles with silica cores and gold shells, have attracted tremendous attention over the past decade as nanoshells have emerged as a promising tool for cancer therapy and bioimaging enhancement. This Account examines the design and synthesis of nanoshell-based theranostic agents, their plasmon-derived optical properties, and their corresponding applications. We discuss the design and preparation of nanoshell complexes and their ability to enhance the photoluminescence of fluorophores while maintaining their properties as MR contrast agents. In this Account, we discuss the underlying physical principles that contribute to the photothermal response of nanoshells. We then elucidate the photophysical processes that induce nanoshells to enhance the fluorescence of weak near-infrared fluorophores. Nanoshells illuminated with resonant light are either strong optical absorbers or scatterers, properties that give rise to their unique capabilities. These physical processes have been harnessed to visualize and eliminate cancer cells. We describe the application of nanoshells as a contrast agent for optical coherence tomography of breast carcinoma cells in vivo. Our recent studies examine nanoshells as a multimodal theranostic probe, using these nanoparticles for near-infrared fluorescence and magnetic resonance imaging (MRI) and for the photothermal ablation of cancer cells. Multimodal nanoshells show theranostic potential for imaging subcutaneous breast cancer tumors in animal models and the distribution of tumors in various tissues. Nanoshells also show promise as light-triggered gene therapy vectors, adding temporal control to the spatial control characteristic of nanoparticle-based gene therapy approaches. We describe the fabrication of DNA-conjugated nanoshell complexes and compare the efficiency of light-induced and thermally-induced release of DNA. Double-stranded DNA nanoshells also provide a way to deliver small molecules into cells: we describe the delivery and light-triggered release of DAPI (4',6-diamidino-2-phenylindole), a dye molecule used to stain DNA in the nuclei of cells.

Electronic states and optical properties of single donor in GaN conical quantum dot with spherical edge

NASA Astrophysics Data System (ADS)

El Aouami, A.; Feddi, E.; El-Yadri, M.; Aghoutane, N.; Dujardin, F.; Duque, C. A.; Phuc, Huynh Vinh

2018-02-01

In this paper we present a theoretical investigation of quantum confinement effects on the electron and single donor states in GaN conical quantum dot with spherical edge. In the framework of the effective mass approximation, the Schrödinger equations of electron and donor have been solved analytically in an infinite potential barrier model. Our calculations show that the energies of electron and donor impurity are affected by the two characteristic parameters of the structure which are the angle Ω and the radial dimension R. We show that, despite the fact that the reduction of the two parameters Ω and R leads to the same confinement effects, the energy remains very sensitive to the variation of the radial part than the variation of the angular part. The analysis of the photoionization cross-section corresponding to optical transitions between the conduction band and the first donor energy level shows clearly that the reduction of the radius R causes a shift in resonance peaks towards the high energies. On the other hand, the optical transitions between 1 s - 1 p , 1 p - 1 d and 1 p - 2 s show that the increment of the conical aperture Ω (or reduction of R) implies a displacement of the excitation energy to higher energies.

Relationship between lenticular power and refractive error in children with hyperopia.

PubMed

Tomomatsu, Takeshi; Kono, Shinjiro; Arimura, Shogo; Tomomatsu, Yoko; Matsumura, Takehiro; Takihara, Yuji; Inatani, Masaru; Takamura, Yoshihiro

2013-01-01

To evaluate the contribution of axial length, and lenticular and corneal power to the spherical equivalent refractive error in children with hyperopia between 3 and 13 years of age, using noncontact optical biometry. There were 62 children between 3 and 13 years of age with hyperopia (+2 diopters [D] or more) who underwent automated refraction measurement with cycloplegia, to measure spherical equivalent refractive error and corneal power. Axial length was measured using an optic biometer that does not require contact with the cornea. The refractive power of the lens was calculated using the Sanders-Retzlaff-Kraff formula. Single regression analysis was used to evaluate the correlation among the optical parameters. There was a significant positive correlation between age and axial length (P = 0.0014); however, the degree of hyperopia did not decrease with aging (P = 0.59). There was a significant negative correlation between age and the refractive power of the lens (P = 0.0001) but not that of the cornea (P = 0.43). A significant negative correlation was observed between the degree of hyperopia and lenticular power (P < 0.0001). Although this study is small scale and cross sectional, the analysis, using noncontact biometry, showed that lenticular power was negatively correlated with refractive error and age, indicating that lower lens power may contribute to the degree of hyperopia.

Design of a normal incidence multilayer imaging x-ray microscope.

PubMed

Shealy, D L; Gabardi, D R; Hoover, R B; Walker, A B; Lindblom, J F; Barbee, T W

1989-01-01

Normal incidence multilayer Cassegrain x-ray telescopes were flown on the Stanford/MSFC Rocket X-Ray Spectroheliograph. These instruments produced high spatial resolution images of the Sun and conclusively demonstrated that doubly reflecting multilayer x-ray optical systems are feasible. The images indicated that aplanatic imaging soft x-ray /EUV microscopes should be achievable using multilayer optics technology. We have designed a doubly reflecting normal incidence multilayer imaging x-ray microscope based on the Schwarzschild configuration. The Schwarzschild microscope utilizes two spherical mirrors with concentric radii of curvature which are chosen such that the third-order spherical aberration and coma are minimized. We discuss the design of the microscope and the results of the optical system ray trace analysis which indicates that diffraction-limited performance with 600 Å spatial resolution should be obtainable over a 1 mm field of view at a wavelength of 100 Å. Fabrication of several imaging soft x-ray microscopes based upon these designs, for use in conjunction with x-ray telescopes and laser fusion research, is now in progress. High resolution aplanatic imaging x-ray microscopes using normal incidence multilayer x-ray mirrors should have many important applications in advanced x-ray astronomical instrumentation, x-ray lithography, biological, biomedical, metallurgical, and laser fusion research.

Single-cell adhesion probed in-situ using optical tweezers: A case study with Saccharomyces cerevisiae

NASA Astrophysics Data System (ADS)

Castelain, Mickaël; Rouxhet, Paul G.; Pignon, Frédéric; Magnin, Albert; Piau, Jean-Michel

2012-06-01

A facile method of using optical trapping to measure cell adhesion forces is presented and applied to the adhesion of Saccharomyces cerevisiae on glass, in contact with solutions of different compositions. Trapping yeast cells with optical tweezers (OT) is not perturbed by cell wall deformation or cell deviation from a spherical shape. The trapping force calibration requires correction not only for the hydrodynamic effect of the neighboring wall but also for spherical aberrations affecting the focal volume and the trap stiffness. Yeast cells trapped for up to 5 h were still able to undergo budding but showed an increase of doubling time. The proportion of adhering cells showed the expected variation according to the solution composition. The detachment force varied in the same way. This observation and the fact that the detachment stress was exerted parallel to the substrate surface point to the role of interactions involving solvated macromolecules. Both the proportion of adhering cells and the removal force showed a distribution which, in our experimental conditions, must be attributed to a heterogeneity of surface properties at the cell level or at the subcellular scale. As compared with magnetic tweezers, atomic force microscopy, and more conventional ways of studying cell adhesion (shear-flow cells), OT present several advantages that are emphasized in this paper.

An Investigation of the Eighteenth-Century Achromatic Telescope

ERIC Educational Resources Information Center

Jaecks, Duane H.

2010-01-01

The optical quality and properties of over 200 telescopes residing in museums and private collections have been measured and tested with the goal of obtaining new information about the early development of the achromatic lens (1757-1770). Quantitative measurements of the chromatic and spherical aberration of telescope objective lenses were made…

Chalcogenide glass microlenses by inkjet printing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanchez, Eric A.; Waldmann, Maike; Arnold, Craig B.

We demonstrate micrometer scale mid-IR lenses for integrated optics, using solution-based inkjet printing techniques and subsequent processing. Arsenic sulfide spherical microlenses with diameters of 10-350 {mu}m and focal lengths of 10-700 {mu}m have been fabricated. The baking conditions can be used to tune the precise focal length.

Application of point-diffraction interferometry to testing infrared imaging systems

NASA Astrophysics Data System (ADS)

Smartt, Raymond N.; Paez, Gonzalo

2004-11-01

Point-diffraction interferometry has found wide applications spanning much of the electromagnetic spectrum, including both near- and far-infrared wavelengths. Any telescopic, spectroscopic or other imaging system that converts an incident plane or spherical wavefront into an accessible point-like image can be tested at an intermediate image plane or at the principal image plane, in situ. Angular field performance can be similarly tested with inclined incident wavefronts. Any spatially coherent source can be used, but because of the available flux, it is most convenient to use a laser source. The simplicity of the test setup can allow testing of even large and complex fully-assembled systems. While purely reflective IR systems can be conveniently tested at visible wavelengths (apart from filters), catadioptric systems could be evaluated using an appropriate source and an IRPDI, with an imaging and recording system. PDI operating principles are briefly reviewed, and some more recent developments and interesting applications briefly discussed. Alternative approaches and recommended procedures for testing IR imaging systems, including the thermal IR, are suggested. An example of applying point-diffraction interferometry to testing a relatively low angular-resolution, optically complex IR telescopic system is presented.

Design and Fabrication of Aspheric Microlens Array for Optical Read-Only-Memory Card System

NASA Astrophysics Data System (ADS)

Kim, Hongmin; Jeong, Gibong; Kim, Young‑Joo; Kang, Shinill

2006-08-01

An optical head based on the Talbot effect with an aspheric microlens array for an optical read-only-memory (ROM) card system was designed and fabricated. The mathematical expression for the wavefield diffracted by a periodic microlens array showed that the amplitude distribution at the Talbot plane from the focal plane of the microlens array was identically equal to that at the focal plane. To use a reflow microlens array as a master pattern of an ultraviolet-imprinted (UV-imprinted) microlens array, the reflow microlens was defined as having an aspheric shape. To obtain optical probes with good optical qualities, a microlens array with the minimum spherical aberration was designed by ray tracing. The reflow condition was optimized to realize the master pattern of a microlens with a designed aspheric shape. The intensity distribution of the optical probes at the Talbot plane from the focal plane showed a diffraction-limited shape.

Analysis and design of optical systems by use of sensitivity analysis of skew ray tracing

NASA Astrophysics Data System (ADS)

Lin, Psang Dain; Lu, Chia-Hung

2004-02-01

Optical systems are conventionally evaluated by ray-tracing techniques that extract performance quantities such as aberration and spot size. Current optical analysis software does not provide satisfactory analytical evaluation functions for the sensitivity of an optical system. Furthermore, when functions oscillate strongly, the results are of low accuracy. Thus this work extends our earlier research on an advanced treatment of reflected or refracted rays, referred to as sensitivity analysis, in which differential changes of reflected or refracted rays are expressed in terms of differential changes of incident rays. The proposed sensitivity analysis methodology for skew ray tracing of reflected or refracted rays that cross spherical or flat boundaries is demonstrated and validated by the application of a cat's eye retroreflector to the design and by the image orientation of a system with noncoplanar optical axes. The proposed sensitivity analysis is projected as the nucleus of other geometrical optical computations.

Analysis and Design of Optical Systems by Use of Sensitivity Analysis of Skew Ray Tracing

NASA Astrophysics Data System (ADS)

Dain Lin, Psang; Lu, Chia-Hung

2004-02-01

Optical systems are conventionally evaluated by ray-tracing techniques that extract performance quantities such as aberration and spot size. Current optical analysis software does not provide satisfactory analytical evaluation functions for the sensitivity of an optical system. Furthermore, when functions oscillate strongly, the results are of low accuracy. Thus this work extends our earlier research on an advanced treatment of reflected or refracted rays, referred to as sensitivity analysis, in which differential changes of reflected or refracted rays are expressed in terms of differential changes of incident rays. The proposed sensitivity analysis methodology for skew ray tracing of reflected or refracted rays that cross spherical or flat boundaries is demonstrated and validated by the application of a cat ?s eye retroreflector to the design and by the image orientation of a system with noncoplanar optical axes. The proposed sensitivity analysis is projected as the nucleus of other geometrical optical computations.

Optical and biometric relationships of the isolated pig crystalline lens.

PubMed

Vilupuru, A S; Glasser, A

2001-07-01

To investigate the interrelationships between optical and biometric properties of the porcine crystalline lens, to compare these findings with similar relationships found for the human lens and to attempt to fit this data to a geometric model of the optical and biometric properties of the pig lens. Weight, focal length, spherical aberration, surface curvatures, thickness and diameters of 20 isolated pig lenses were measured and equivalent refractive index was calculated. These parameters were compared and used to geometrically model the pig lens. Linear relationships were identified between many of the lens biometric and optical properties. The existence of these relationships allowed a simple geometrical model of the pig lens to be calculated which offers predictions of the optical properties. The linear relationships found and the agreement observed between measured and modeled results suggest that the pig lens confirms to a predictable, preset developmental pattern and that the optical and biometric properties are predictably interrelated.

Quality of Vision in Eyes With Epiphora Undergoing Lacrimal Passage Intubation.

PubMed

Koh, Shizuka; Inoue, Yasushi; Ochi, Shintaro; Takai, Yoshihiro; Maeda, Naoyuki; Nishida, Kohji

2017-09-01

To investigate visual function and optical quality in eyes with epiphora undergoing lacrimal passage intubation. Prospective case series. Thirty-four eyes of 30 patients with lacrimal passage obstruction were enrolled. Before and 1 month after lacrimal passage intubation, functional visual acuity (FVA), higher-order aberrations (HOAs), lower tear meniscus, and tear clearance were assessed. An FVA measurement system was used to examine changes in continuous visual acuity (VA) over time, and visual function parameters such as FVA, visual maintenance ratio, and blink frequency were obtained. Sequential ocular HOAs were measured for 10 seconds after the blink using a wavefront sensor. Aberration data were analyzed in the central 4 mm for coma-like, spherical-like, and total HOAs. Fluctuation and stability indices of the total HOAs over time were calculated. Lower tear meniscus was assessed by anterior segment optical coherence tomography. After lacrimal passage intubation, visual function significantly improved, as indicated by improved FVA (P = .003) and visual maintenance ratio (P < .001). Blink frequency decreased significantly after treatment (P = .01). Optical quality significantly improved, as indicated by a decrease in coma-like aberrations (P = .003), spherical-like aberrations (P = .018), and total HOAs (P = .001). Stability index increased (P < .001) and fluctuation index decreased (P = .019), and tear meniscus dimension decreased (P < .001). Lacrimal passage intubation for eyes with epiphora significantly improved visual function and optical quality via patency of the lacrimal passage. Copyright © 2017 Elsevier Inc. All rights reserved.

Using Spherical-Harmonics Expansions for Optics Surface Reconstruction from Gradients.

PubMed

Solano-Altamirano, Juan Manuel; Vázquez-Otero, Alejandro; Khikhlukha, Danila; Dormido, Raquel; Duro, Natividad

2017-11-30

In this paper, we propose a new algorithm to reconstruct optics surfaces (aka wavefronts) from gradients, defined on a circular domain, by means of the Spherical Harmonics. The experimental results indicate that this algorithm renders the same accuracy, compared to the reconstruction based on classical Zernike polynomials, using a smaller number of polynomial terms, which potentially speeds up the wavefront reconstruction. Additionally, we provide an open-source C++ library, released under the terms of the GNU General Public License version 2 (GPLv2), wherein several polynomial sets are coded. Therefore, this library constitutes a robust software alternative for wavefront reconstruction in a high energy laser field, optical surface reconstruction, and, more generally, in surface reconstruction from gradients. The library is a candidate for being integrated in control systems for optical devices, or similarly to be used in ad hoc simulations. Moreover, it has been developed with flexibility in mind, and, as such, the implementation includes the following features: (i) a mock-up generator of various incident wavefronts, intended to simulate the wavefronts commonly encountered in the field of high-energy lasers production; (ii) runtime selection of the library in charge of performing the algebraic computations; (iii) a profiling mechanism to measure and compare the performance of different steps of the algorithms and/or third-party linear algebra libraries. Finally, the library can be easily extended to include additional dependencies, such as porting the algebraic operations to specific architectures, in order to exploit hardware acceleration features.

Using Spherical-Harmonics Expansions for Optics Surface Reconstruction from Gradients

PubMed Central

Solano-Altamirano, Juan Manuel; Khikhlukha, Danila

2017-01-01

In this paper, we propose a new algorithm to reconstruct optics surfaces (aka wavefronts) from gradients, defined on a circular domain, by means of the Spherical Harmonics. The experimental results indicate that this algorithm renders the same accuracy, compared to the reconstruction based on classical Zernike polynomials, using a smaller number of polynomial terms, which potentially speeds up the wavefront reconstruction. Additionally, we provide an open-source C++ library, released under the terms of the GNU General Public License version 2 (GPLv2), wherein several polynomial sets are coded. Therefore, this library constitutes a robust software alternative for wavefront reconstruction in a high energy laser field, optical surface reconstruction, and, more generally, in surface reconstruction from gradients. The library is a candidate for being integrated in control systems for optical devices, or similarly to be used in ad hoc simulations. Moreover, it has been developed with flexibility in mind, and, as such, the implementation includes the following features: (i) a mock-up generator of various incident wavefronts, intended to simulate the wavefronts commonly encountered in the field of high-energy lasers production; (ii) runtime selection of the library in charge of performing the algebraic computations; (iii) a profiling mechanism to measure and compare the performance of different steps of the algorithms and/or third-party linear algebra libraries. Finally, the library can be easily extended to include additional dependencies, such as porting the algebraic operations to specific architectures, in order to exploit hardware acceleration features. PMID:29189722

A comparative study of spherical and flat-Earth geopotential modeling at satellite elevations

NASA Technical Reports Server (NTRS)

Parrott, M. H.; Hinze, W. J.; Braile, L. W.; Vonfrese, R. R. B.

1985-01-01

Flat-Earth modeling is a desirable alternative to the complex spherical-Earth modeling process. These methods were compared using 2 1/2 dimensional flat-earth and spherical modeling to compute gravity and scalar magnetic anomalies along profiles perpendicular to the strike of variably dimensioned rectangular prisms at altitudes of 150, 300, and 450 km. Comparison was achieved with percent error computations (spherical-flat/spherical) at critical anomaly points. At the peak gravity anomaly value, errors are less than + or - 5% for all prisms. At 1/2 and 1/10 of the peak, errors are generally less than 10% and 40% respectively, increasing to these values with longer and wider prisms at higher altitudes. For magnetics, the errors at critical anomaly points are less than -10% for all prisms, attaining these magnitudes with longer and wider prisms at higher altitudes. In general, in both gravity and magnetic modeling, errors increase greatly for prisms wider than 500 km, although gravity modeling is more sensitive than magnetic modeling to spherical-Earth effects. Preliminary modeling of both satellite gravity and magnetic anomalies using flat-Earth assumptions is justified considering the errors caused by uncertainties in isolating anomalies.

Optical properties of soot particles: measurement - model comparison

NASA Astrophysics Data System (ADS)

Forestieri, S.; Lambe, A. T.; Lack, D.; Massoli, P.; Cross, E. S.; Dubey, M.; Mazzoleni, C.; Olfert, J.; Freedman, A.; Davidovits, P.; Onasch, T. B.; Cappa, C. D.

2013-12-01

Soot, a product of incomplete combustion, plays an important role in the earth's climate system through the absorption and scattering of solar radiation. In order to accurately model the direct radiative impact of black carbon (BC), the refractive index and shape dependent scattering and absorption characteristics must be known. At present, the assumed shape remains highly uncertain because BC particles are fractal-like, being agglomerates of smaller (20-40 nm) spherules, yet traditional optical models such as Mie theory typically assume a spherical particle morphology. To investigate the ability of various optical models to reproduce observed BC optical properties, we measured light absorption and extinction coefficients of methane and ethylene flame soot particles. Optical properties were measured by multiple instruments: absorption by a dual cavity ringdown photoacoustic spectrometer (CRD-PAS), absorption and scattering by a 3-wavelength photoacoustic/nephelometer spectrometer (PASS-3) and extinction and scattering by a cavity attenuated phase shift spectrometer (CAPS). Soot particle mass was quantified using a centrifugal particle mass analyzer (CPMA) and mobility size was measured with a scanning mobility particle sizer (SMPS). Measurements were made for nascent soot particles and for collapsed soot particles following coating with dioctyl sebacate or sulfuric acid and thermal denuding to remove the coating. Wavelength-dependent refractive indices for the sampled particles were derived by fitting the observed absorption and extinction cross-sections to spherical particle Mie theory and Rayleigh-Debye-Gans theory. The Rayleigh-Debye-Gans approximation assumes that the absorption properties of soot are dictated by the individual spherules and neglects interaction between them. In general, Mie theory reproduces the observed absorption and extinction cross-sections for particles with volume equivalent diameters (VED) < ~160 nm, but systematically predicts lower absorption cross-sections relative to observations for larger particles with VED > ~160 nm. The discrepancy is most pronounced for measurements made at shorter wavelengths. In contrast, Rayleigh-Debye-Gans theory, which does not assume spherical particle morphology, exhibited good agreement with the observations for all particle diameters and wavelengths. These results indicate that the use of Mie theory to describe the absorption behavior of particles >160 nm VED will underestimate the absorption by these particles. Concurrent measurements of the absorption Angstrom exponent and the single scattering albedo, and their dependence on particle size, will also be discussed.

A new generation of IC based beam steering devices for free-space optical communication

NASA Astrophysics Data System (ADS)

Bedi, Vijit

Free Space Optical (FSO) communication has tremendously advanced within the last decade to meet the ever increasing demand for higher communication bandwidth. Advancement in laser technology since its invention in the 1960's [1] attracted them to be the dominant source in FSO communication modules. The future of FSO systems lay in implementing semiconductor lasers due to their small size, power efficiency and mass fabrication abilities. In the near future, these systems are very likely to be used in space and ground based applications and revolutionary beam steering technologies will be required for distant communications in free-space. The highly directional characteristic inherent to a laser beam challenges and calls for new beam pointing and steering technologies for such type of communication. In this dissertation, research is done on a novel FSO communication device based on semiconductor lasers for high bandwidth communication. The "Fly eye transceiver" is an extremely wide steering bandwidth, completely non-mechanical FSO laser communication device primarily designed to replace traditional mechanical beam steering optical systems. This non-mechanical FSO device possesses a full spherical steering range and a very high tracking bandwidth. Inspired by the evolutionary model of a fly's eye, the full spherical steering range is assured by electronically controlled switching of its sub-eyes. Non mechanical technologies used in the past for beam steering such as acousto-optic Bragg cells, liquid crystal arrays or piezoelectric elements offer the wide steering bandwidth and fast response time, but are limited in their angular steering range. Mechanical gimbals offer a much greater steering range but face a much slower response time or steering bandwidth problem and often require intelligent adaptive controls with bulky driver amplifiers to feed their actuators. As a solution to feed both the fast and full spherical steering, the Fly-eye transceiver is studied as part of my PhD work. The design tool created for the research of the fly eye is then used to study different applications that may be implemented with the concept. Research is done on the mathematical feasibility, modeling, design, application of the technology, and its characterization in a simulation environment. In addition, effects of atmospheric turbulence on beam propagation in free space, and applying data security using optical encryption are also researched.

PDSM characterization for fabrication of free-space OXC optical components

NASA Astrophysics Data System (ADS)

Argueta, Victor; Fitzpatrick, Brianna

2017-11-01

In 2007 Dr Khine et al published a paper where they presented a technique using thermoplastics and PDMS to create microfluidic patterns1. Their technique involves printing a pattern in a polystyrene sheet using a laser printer. Once the pattern is transfer the polystyrene sheets they are heated to reduce their size. By printing the same pattern of the plastic sheets before heating, it is possible to control the height up to 80 μm and the width as thin as 65 μm1, 2. This technique is attractive to be used in optical fabrication due to its versatility, low cost and fast prototyping. However, in order to fabricate optical systems, we will need to control the refractive index of PDMS to allow design of basic optical components like waveguides, beam splitter, or diffuse reflectors; or more complex structures like interferometers, optical microfluidic lab-on-chip, micro-lens arrays. Several techniques exist to control the refractive index for PDMS either by controlling the curing temperature, the ratio between the base and curing agent, or by curing using UV light3-5. In this paper, we present the changes on refractive index by changing the curing temperature for different base/reaction agent ratios. We then apply these results to fabricate an optical component for a free-space optical cross-connect (OXC). Optical cross-connects are an important network element for constructing the next generation of optical networks, where provisioning (reconfiguration), scalability, and fast restoration will be needed6-8. The main attraction of all-optical switching is that it enables routing of optical data signals without the need for conversion to electrical signals, and therefore, is independent of data rate and data protocols. We have proposed previously9, 11 a new approach for an OXC. Our architecture is a free-space 3-D while still using digital MEMS. Our system is based on the optical White cell12, which consists of three spherical mirrors among which light can circulate. In Section II, we will briefly mention the basic characteristics of the binary White cell OXC configuration. Section III we will introduce the changes induced on curing PDMS, our SDD design and its fabrication for two different beam displacements. Finally, in Section IV, we will present the summary and conclusions of our work.

A Bio-inspired Collision Avoidance Model Based on Spatial Information Derived from Motion Detectors Leads to Common Routes

PubMed Central

Bertrand, Olivier J. N.; Lindemann, Jens P.; Egelhaaf, Martin

2015-01-01

Avoiding collisions is one of the most basic needs of any mobile agent, both biological and technical, when searching around or aiming toward a goal. We propose a model of collision avoidance inspired by behavioral experiments on insects and by properties of optic flow on a spherical eye experienced during translation, and test the interaction of this model with goal-driven behavior. Insects, such as flies and bees, actively separate the rotational and translational optic flow components via behavior, i.e. by employing a saccadic strategy of flight and gaze control. Optic flow experienced during translation, i.e. during intersaccadic phases, contains information on the depth-structure of the environment, but this information is entangled with that on self-motion. Here, we propose a simple model to extract the depth structure from translational optic flow by using local properties of a spherical eye. On this basis, a motion direction of the agent is computed that ensures collision avoidance. Flying insects are thought to measure optic flow by correlation-type elementary motion detectors. Their responses depend, in addition to velocity, on the texture and contrast of objects and, thus, do not measure the velocity of objects veridically. Therefore, we initially used geometrically determined optic flow as input to a collision avoidance algorithm to show that depth information inferred from optic flow is sufficient to account for collision avoidance under closed-loop conditions. Then, the collision avoidance algorithm was tested with bio-inspired correlation-type elementary motion detectors in its input. Even then, the algorithm led successfully to collision avoidance and, in addition, replicated the characteristics of collision avoidance behavior of insects. Finally, the collision avoidance algorithm was combined with a goal direction and tested in cluttered environments. The simulated agent then showed goal-directed behavior reminiscent of components of the navigation behavior of insects. PMID:26583771

Integration of a UV curable polymer lens and MUMPs structures on a SOI optical bench

NASA Astrophysics Data System (ADS)

Hsieh, Jerwei; Hsiao, Sheng-Yi; Lai, Chun-Feng; Fang, Weileun

2007-08-01

This work presents the design concept of integrating a polymer lens, poly-Si MUMPs and single-crystal-silicon HARM structures on a SOI wafer to form a silicon optical bench. This approach enables the monolithic integration of various optical components on the wafer so as to improve the design flexibility of the silicon optical bench. Fabrication processes, including surface and bulk micromachining on the SOI wafer, have been established to realize bi-convex spherical polymer lenses with in-plane as well as out-of-plane optical axes. In addition, a micro device consisting of an in-plane polymer lens, a thick fiber holder and a mechanical shutter driven by an electrothermal actuator is also demonstrated using the present approach. In summary, this study significantly improves the design flexibility as well as the functions of SiOBs.

Lenticular accommodation in relation to ametropia: the chick model.

PubMed

Choh, Vivian; Sivak, Jacob G

2005-03-04

Our goal was to determine whether experimentally induced ametropias have an effect on lenticular accommodation and spherical aberration. Form-deprivation myopia and hyperopia were induced in one eye of hatchling chicks by application of a translucent goggle and +15 D lens, respectively. After 7 days, eyes were enucleated and lenses were optically scanned prior to accommodation, during accommodation, and after accommodation. Accommodation was induced by electrical stimulation of the ciliary nerve. Lenticular focal lengths for form-deprived eyes were significantly shorter than for their controls and accommodation-associated changes in focal length were significantly smaller in myopic eyes compared to their controls. For eyes imposed with +15 D blur, focal lengths were longer than those for their controls and accommodative changes were greater. Spherical aberration of the lens increased with accommodation in both form-deprived and lens-treated birds, but induction of ametropia had no effect on lenticular spherical aberration in general. Nonmonotonicity from lenticular spherical aberration increased during accommodation but effects of refractive error were equivocal. The crystalline lens contributes to refractive error changes of the eye both in the case of myopia and hyperopia. These changes are likely attributable to global changes in the size and shape of the eye.

A discrete spherical harmonics method for radiative transfer analysis in inhomogeneous polarized planar atmosphere

NASA Astrophysics Data System (ADS)

Tapimo, Romuald; Tagne Kamdem, Hervé Thierry; Yemele, David

2018-03-01

A discrete spherical harmonics method is developed for the radiative transfer problem in inhomogeneous polarized planar atmosphere illuminated at the top by a collimated sunlight while the bottom reflects the radiation. The method expands both the Stokes vector and the phase matrix in a finite series of generalized spherical functions and the resulting vector radiative transfer equation is expressed in a set of polar directions. Hence, the polarized characteristics of the radiance within the atmosphere at any polar direction and azimuthal angle can be determined without linearization and/or interpolations. The spatial dependent of the problem is solved using the spectral Chebyshev method. The emergent and transmitted radiative intensity and the degree of polarization are predicted for both Rayleigh and Mie scattering. The discrete spherical harmonics method predictions for optical thin atmosphere using 36 streams are found in good agreement with benchmark literature results. The maximum deviation between the proposed method and literature results and for polar directions \\vert μ \\vert ≥0.1 is less than 0.5% and 0.9% for the Rayleigh and Mie scattering, respectively. These deviations for directions close to zero are about 3% and 10% for Rayleigh and Mie scattering, respectively.

Evolution and statistics of non-sphericity of dark matter halos from cosmological N-body simulation

NASA Astrophysics Data System (ADS)

Suto, Daichi; Kitayama, Tetsu; Nishimichi, Takahiro; Sasaki, Shin; Suto, Yasushi

2016-12-01

We revisit the non-sphericity of cluster-mass-scale halos from cosmological N-body simulation on the basis of triaxial modeling. In order to understand the difference between the simulation results and the conventional ellipsoidal collapse model (EC), we first consider the evolution of individual simulated halos. The major difference between EC and the simulation becomes appreciable after the turnaround epoch. Moreover, it is sensitive to the individual evolution history of each halo. Despite such strong dependence on individual halos, the resulting non-sphericity of halos exhibits weak but robust mass dependence in a statistical fashion; massive halos are more spherical up to the turnaround, but gradually become less spherical by z = 0. This is clearly inconsistent with the EC prediction: massive halos are usually more spherical. In addition, at z = 0, inner regions of the simulated halos are less spherical than outer regions; that is, the density distribution inside the halos is highly inhomogeneous and therefore not self-similar (concentric ellipsoids with the same axis ratio and orientation). This is also inconsistent with the homogeneous density distribution that is commonly assumed in EC. Since most of previous fitting formulae for the probability distribution function (PDF) of the axis ratio of triaxial ellipsoids have been constructed under the self-similarity assumption, they are not accurate. Indeed, we compute the PDF of the projected axis ratio a1/a2 directly from the simulation data without the self-similarity assumption, and find that it is very sensitive to the assumption. The latter needs to be carefully taken into account in direct comparison with observations, and therefore we provide an empirical fitting formula for the PDF of a1/a2. Our preliminary analysis suggests that the derived PDF of a1/a2 roughly agrees with the current weak-lensing observations. More importantly, the present results will be useful for future exploration of the non-sphericity of clusters in X-ray and optical observations.

How should spin-weighted spherical functions be defined?

NASA Astrophysics Data System (ADS)

Boyle, Michael

2016-09-01

Spin-weighted spherical functions provide a useful tool for analyzing tensor-valued functions on the sphere. A tensor field can be decomposed into complex-valued functions by taking contractions with tangent vectors on the sphere and the normal to the sphere. These component functions are usually presented as functions on the sphere itself, but this requires an implicit choice of distinguished tangent vectors with which to contract. Thus, we may more accurately say that spin-weighted spherical functions are functions of both a point on the sphere and a choice of frame in the tangent space at that point. The distinction becomes extremely important when transforming the coordinates in which these functions are expressed, because the implicit choice of frame will also transform. Here, it is proposed that spin-weighted spherical functions should be treated as functions on the spin or rotation groups, which simultaneously tracks the point on the sphere and the choice of tangent frame by rotating elements of an orthonormal basis. In practice, the functions simply take a quaternion argument and produce a complex value. This approach more cleanly reflects the geometry involved, and allows for a more elegant description of the behavior of spin-weighted functions. In this form, the spin-weighted spherical harmonics have simple expressions as elements of the Wigner 𝔇 representations, and transformations under rotation are simple. Two variants of the angular-momentum operator are defined directly in terms of the spin group; one is the standard angular-momentum operator L, while the other is shown to be related to the spin-raising operator ð.

Acoustic reciprocity: An extension to spherical harmonics domain.

PubMed

Samarasinghe, Prasanga; Abhayapala, Thushara D; Kellermann, Walter

2017-10-01

Acoustic reciprocity is a fundamental property of acoustic wavefields that is commonly used to simplify the measurement process of many practical applications. Traditionally, the reciprocity theorem is defined between a monopole point source and a point receiver. Intuitively, it must apply to more complex transducers than monopoles. In this paper, the authors formulate the acoustic reciprocity theory in the spherical harmonics domain for directional sources and directional receivers with higher order directivity patterns.

An Accurate Analytic Approximation for Light Scattering by Non-absorbing Spherical Aerosol Particles

NASA Astrophysics Data System (ADS)

Lewis, E. R.

2017-12-01

The scattering of light by particles in the atmosphere is a ubiquitous and important phenomenon, with applications to numerous fields of science and technology. The problem of scattering of electromagnetic radiation by a uniform spherical particle can be solved by the method of Mie and Debye as a series of terms depending on the size parameter, x=2πr/λ, and the complex index of refraction, m. However, this solution does not provide insight into the dependence of the scattering on the radius of the particle, the wavelength, or the index of refraction, or how the scattering varies with relative humidity. Van de Hulst demonstrated that the scattering efficiency (the scattering cross section divided by the geometric cross section) of a non-absorbing sphere, over a wide range of particle sizes of atmospheric importance, depends not on x and m separately, but on the quantity 2x(m-1); this is the basis for the anomalous diffraction approximation. Here an analytic approximation for the scattering efficiency of a non-absorbing spherical particle is presented in terms of this new quantity that is accurate over a wide range of particle sizes of atmospheric importance and which readily displays the dependences of the scattering efficiency on particle radius, index of refraction, and wavelength. For an aerosol for which the particle size distribution is parameterized as a gamma function, this approximation also yields analytical results for the scattering coefficient and for the Ångström exponent, with the dependences of scattering properties on wavelength and index of refraction clearly displayed. This approximation provides insight into the dependence of light scattering properties on factors such as relative humidity, readily enables conversion of scattering from one index of refraction to another, and demonstrates the conditions under which the aerosol index (the product of the aerosol optical depth and the Ångström exponent) is a useful proxy for the number of cloud condensation nuclei.

Influence of refractive condition on retinal vasculature complexity in younger subjects.

PubMed

Azemin, Mohd Zulfaezal Che; Daud, Norsyazwani Mohamad; Ab Hamid, Fadilah; Zahari, Ilyanoon; Sapuan, Abdul Halim

2014-01-01

The aim of this study was to compare the retinal vasculature complexity between emmetropia, and myopia in younger subjects. A total of 82 patients (24.12 ± 1.25 years) with two types of refractive conditions, myopia and emmetropia were enrolled in this study. Refraction data were converted to spherical equivalent refraction. These retinal images (right eyes) were obtained from NAVIS Lite Image Filing System and the vasculature complexity was measured by fractal dimension (D f ), quantified using a computer software following a standardized protocol. There was a significant difference (P < 0.05) in the value of D f between emmetropic (1.5666 ± 0.0160) and myopic (1.5588 ± 0.0142) groups. A positive correlation (rho = 0.260, P < 0.05) between the D f and the spherical equivalent refraction was detected in this study. Using a linear model, it was estimated that 6.7% of the variation in D f could be explained by spherical equivalent refraction. This study provides valuable findings about the effect of moderate to high myopia on the fractal dimension of the retinal vasculature network. These results show that myopic refraction in younger subjects was associated with a decrease in D f , suggesting a loss of retinal vessel density with moderate to high myopia.

Analytical description of lateral binding force exerted on bi-sphere induced by high-order Bessel beams

NASA Astrophysics Data System (ADS)

Bai, J.; Wu, Z. S.; Ge, C. X.; Li, Z. J.; Qu, T.; Shang, Q. C.

2018-07-01

Based on the generalized multi-particle Mie equation (GMM) and Electromagnetic Momentum (EM) theory, the lateral binding force (BF) exerted on bi-sphere induced by an arbitrary polarized high-order Bessel beam (HOBB) is investigated with particular emphasis on the half-conical angle of the wave number components and the order (or topological charge) of the beam. The illuminating HOBB with arbitrary polarization angle is described in terms of beam shape coefficients (BSCs) within the framework of generalized Lorenz-Mie theories (GLMT). Utilizing the vector addition theorem of the spherical vector wave functions (SVWFs), the interactive scattering coefficients are derived through the continuous boundary conditions on which the interaction of the bi-sphere is considered. Numerical effects of various parameters such as beam polarization angles, incident wavelengths, particle sizes, material losses and the refractive index, including the cases of weak, moderate, and strong than the surrounding medium are numerically analyzed in detail. The observed dependence of the separation of optically bound particles on the incidence of HOBB is in agreement with earlier theoretical prediction. Accurate investigation of BF induced by HOBB could provide an effective test for further research on BF between more complex particles, which plays an important role in using optical manipulation on particle self-assembly.

Exact density-potential pairs from complex-shifted axisymmetric systems

NASA Astrophysics Data System (ADS)

Ciotti, Luca; Marinacci, Federico

2008-07-01

In a previous paper, the complex-shift method has been applied to self-gravitating spherical systems, producing new analytical axisymmetric density-potential pairs. We now extend the treatment to the Miyamoto-Nagai disc and the Binney logarithmic halo, and we study the resulting axisymmetric and triaxial analytical density-potential pairs; we also show how to obtain the surface density of shifted systems from the complex shift of the surface density of the parent model. In particular, the systems obtained from Miyamoto-Nagai discs can be used to describe disc galaxies with a peanut-shaped bulge or with a central triaxial bar, depending on the direction of the shift vector. By using a constructive method that can be applied to generic axisymmetric systems, we finally show that the Miyamoto-Nagai and the Satoh discs, and the Binney logarithmic halo cannot be obtained from the complex shift of any spherical parent distribution. As a by-product of this study, we also found two new generating functions in closed form for even and odd Legendre polynomials, respectively.

Performance of an untethered micro-optical pressure sensor

NASA Astrophysics Data System (ADS)

Ioppolo, Tindaro; Manzo, Maurizio; Krueger, Paul

2012-11-01

We present analytical and computational studies of the performance of a novel untethered micro-optical pressure sensor for fluid dynamics measurements. In particular, resolution and dynamic range will be presented. The sensor concept is based on the whispering galley mode (WGM) shifts that are observed in micro-scale dielectric optical cavities. A micro-spherical optical cavity (liquid or solid) is embedded in a thin polymeric sheet. The applied external pressure perturbs the morphology of the optical cavity leading to a shift in its optical resonances. The optical sensors are interrogated remotely, by embedding quantum dots or fluorescent dye in the micro-optical cavity. This allows a free space coupling of excitation and monitoring of the optical modes without the need of optical fibers or other cabling. With appropriate excitation and monitoring equipment, the micro-scale sensors can be distributed over a surface (e.g., including flexible biological surfaces) to monitor the local pressure field. We acknowledge the financial support from the National Science Foundation through grant CBET-1133876 with Dr. Horst Henning Winter as the program director.

Evaluation of a Myopic Normative Database for Analysis of Retinal Nerve Fiber Layer Thickness.

PubMed

Biswas, Sayantan; Lin, Chen; Leung, Christopher K S

2016-09-01

Analysis of retinal nerve fiber layer (RNFL) abnormalities with optical coherence tomography in eyes with high myopia has been complicated by high rates of false-positive errors. An understanding of whether the application of a myopic normative database can improve the specificity for detection of RNFL abnormalities in eyes with high myopia is relevant. To evaluate the diagnostic performance of a myopic normative database for detection of RNFL abnormalities in eyes with high myopia (spherical equivalent, -6.0 diopters [D] or less). In this cross-sectional study, 180 eyes with high myopia (mean [SD] spherical equivalent, -8.0 [1.8] D) from 180 healthy individuals were included in the myopic normative database. Another 46 eyes with high myopia from healthy individuals (mean [SD] spherical equivalent, -8.1 [1.8] D) and 74 eyes from patients with high myopia and glaucoma (mean [SD] spherical equivalent, -8.3 [1.9] D) were included for evaluation of specificity and sensitivity. The 95th and 99th percentiles of the mean and clock-hour circumpapillary RNFL thicknesses and the individual superpixel thicknesses of the RNFL thickness map measured by spectral-domain optical coherence tomography were calculated from the 180 eyes with high myopia. Participants were recruited from January 2, 2013, to December 30, 2015. The following 6 criteria of RNFL abnormalities were examined: (1) mean circumpapillary RNFL thickness below the lower 95th or (2) the lower 99th percentile; (3) one clock-hour or more for RNFL thickness below the lower 95th or (4) the lower 99th percentile; and (5) twenty contiguous superpixels or more of RNFL thickness in the RNFL thickness map below the lower 95th or (6) the lower 99th percentile. Specificities and sensitivities for detection of RNFL abnormalities. Of the 46 healthy eyes and 74 eyes with glaucoma studied (from 39 men and 38 women), the myopic normative database showed a higher specificity (63.0%-100%) than did the built-in normative database of the optical coherence tomography instrument (8.7%-87.0%) for detection of RNFL abnormalities across all the criteria examined (differences in specificities between 13.0% [95% CI, 1.1%-24.9%; P = .01] and 54.3% [95% CI, 37.8%-70.9%; P < .001]) except for the criterion of mean RNFL thickness below the lower 99th percentile, in which both normative databases had the same specificities (100%) but the myopic normative database exhibited a higher sensitivity (71.6% vs 86.5%; difference in sensitivities, 14.9% [95% CI, 4.6%-25.1%; P = .002]). The application of a myopic normative database improved the specificity without compromising the sensitivity compared with the optical coherence tomography instrument's built-in normative database for detection of RNFL abnormalities in eyes with high myopia. Inclusion of myopic normative databases should be considered in optical coherence tomography instruments.

Enhanced control of light and sound trajectories with three-dimensional gradient index lenses

NASA Astrophysics Data System (ADS)

Chang, T. M.; Dupont, G.; Enoch, S.; Guenneau, S.

2012-03-01

We numerically study the focusing and bending effects of light and sound waves through heterogeneous isotropic cylindrical and spherical devices. We first point out that transformation optics and acoustics show that the control of light requires spatially varying anisotropic permittivity and permeability, while the control of sound is achieved via spatially anisotropic density and isotropic compressibility. Moreover, homogenization theory applied to electromagnetic and acoustic periodic structures leads to such artificial (although not spatially varying) anisotropic permittivity, permeability and density. We stress that homogenization is thus a natural mathematical tool for the design of structured metamaterials. To illustrate the two-step geometric transform-homogenization approach, we consider the design of cylindrical and spherical electromagnetic and acoustic lenses displaying some artificial anisotropy along their optical axis (direction of periodicity of the structural elements). Applications are sought in the design of Eaton and Luneburg lenses bending light at angles ranging from 90° to 360°, or mimicking a Schwartzchild metric, i.e. a black hole. All of these spherical metamaterials are characterized by a refractive index varying inversely with the radius which is approximated by concentric layers of homogeneous material. We finally propose some structured cylindrical metamaterials consisting of infinitely conducting or rigid toroidal channels in a homogeneous bulk material focusing light or sound waves. The functionality of these metamaterials is demonstrated via full-wave three-dimensional computations using nodal elements in the context of acoustics, and finite edge-elements in electromagnetics.

Nonlinear optical susceptibility described with a spherical formalism applied to coherent anti-Stokes Raman scattering

NASA Astrophysics Data System (ADS)

Cleff, Carsten; Rigneault, Hervé; Brasselet, Sophie; Duboisset, Julien

2017-07-01

We describe coherent Raman scattering in a complete spherical formalism allowing a better understanding of the coherent Raman process with respect to its symmetry properties, which is especially helpful in polarized coherent Raman microscopy. We describe how to build the coherent Raman tensor from spontaneous Raman tensor for crystalline and disordered media. We introduce a distribution function for molecular bonds and show how this distribution function results in a new macroscopic symmetry which can be very different from the symmetry of vibrational modes. Finally, we explicitly show polarization configurations for coherent anti-Stokes Raman scattering to probe specific vibration symmetries in crystalline samples and lipid layers.