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Sample records for light diffraction ellipsometry

  1. Diffraction Ellipsometry Studies of Skeletal Muscle Structure

    NASA Astrophysics Data System (ADS)

    Kerr, William Lloyd

    Many of the techniques used to study the structure and contraction mechanism of muscle rely on the interaction of light or other electromagnetic radiation with the muscle. Some of the most important of these techniques are light and electron microscopy, x-ray diffraction, spectroscopy of muscle fibers "labelled" with spin or fluorescent probes, visible spectrum diffraction, and transmission birefringence. Chapter I of this dissertation reviews these techniques, focussing on what they have to tell us about muscle structure. In Chapter II, we discuss experiments in which the microstructural features of relaxed, skinned fibers compressed with polyvinylpyrollidone were examined by optical diffraction ellipsometry. The change in polarization state of light after interacting with the muscle is described by the differential field ratio (DFR) and birefringence (Deltan). Compression of single fibers with 0%-21% PVP caused an increase in up to 23% and 31% for DFR and Deltan, respectively. Theoretical modelling suggests that the average S-1 tilt angle may be reduced upon compression of the filament lattice. This is supported by experiments in which S-1 was cleaved with alpha-chymotrypsin. Experiments comparing fibers with intact membranes and skinned fibers compressed to an equivalent lattice spacing showed little difference in DFR or Deltan. Chapter III deals with experiments on contracting, intact fibers. The differential field ratio (DFR) was monitored for tetanically contracting muscle fibers subject to rapid (<0.4 msec) release or stretch. Upon stimulation, DFR decreases 14% from its resting value; the half-time for the decrease leads that of tension rise by 10 msecs. This suggests that the movement of cross -bridges precedes tension development and that the average cross-bridge angle is more perpendicular in the contracting state. Upon rapid release of 0.5% of the fiber length, DFR decreases 9.5% further simultaneous with the length step. Rapid and slow recovery phases

  2. Diffraction Ellipsometry Studies on Insect Flight Muscle

    NASA Astrophysics Data System (ADS)

    Shen, Sui

    Characterization of the orientation and distribution of myosin cross-bridge at rigor, relax, low ionic strength (36 mM) and activation (pCa 4.3) conditions are of great interest since these states have been proposed to be transient steps in the cyclical interaction of myosin heads with actin during contraction. Measurements sensitive to the cross-bridge orientation in chemically skinned single muscle fibers of the insect, Lethocerus collossicus have been performed under various physiological conditions using laser diffraction ellipsometry. Determination of both the total birefringence, Deltan, and the differential field ratio, rm DFR (defined as {E_parallel -E_|over E_parallel-E _|}),is necessary for complete characterization of the optical polarization state. For rigor insect fiber, the birefringence value was close to the value we obtained from chemically skinned frog muscle fibers. However, the differential field ratio, DFR, was a negative value for insect fiber, while we always measured a positive value from frog muscle fibers. Polarization states of light diffracted from fibers exhibited a dependence on configurations of structural proteins at different conditions: fluid index matching using o-toluidine, alpha -chymotrypsin cleavage, KCl myosin extraction, rigor state, relaxed state, exogenous S-1 binding on rigor fiber, low ionic strength state, activation state at resting or stretched length. Results of our data analysis suggested that: (1) the negative DFR value of the insect flight muscle was contributed by alpha-actinin arranged perpendicular to the fiber axis in the Z-line, (2) in rigor fiber, 70% of myosin heads are doubly bound (45^circ and 90^ circ) while the rest of 30% are in single head binding configuration (90^circ), (3) myosin heads are randomly oriented in relaxed fiber, (4) mean axial angle is about 62^ circ for exogenous myosin heads binding on rigor fiber, (5) at low ionic strength, 25% of the total myosin heads are weakly attached to actin

  3. Diffraction light analysis method for a diffraction grating imaging lens.

    PubMed

    Ando, Takamasa; Korenaga, Tsuguhiro; Suzuki, Masa-aki; Tanida, Jun

    2014-04-10

    We have developed a new method to analyze the amount and distribution of diffraction light for a diffraction grating lens. We have found that diffraction light includes each-order diffraction light and striped diffraction light. In this paper, we describe characteristics of striped diffraction light and suggest a way to analyze diffraction light. Our analysis method, which considers the structure of diffraction grating steps, can simulate the aberrations of an optical system, each-order diffraction light, and striped diffraction light simultaneously with high accuracy. A comparison between the simulation and experimental results is presented, and we also show how our analysis method can be used to optimize a diffraction grating lens with low flare light.

  4. Optical characterization of group-iv semiconductor alloys using spectroscopic ellipsometry and high resolution x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Fernando, Nalin S.

    Germanium is a group IV semiconductor widely used in the semiconductor optoelectronic industry. It is an indirect band material with the conduction band minimum at the L point. which is 0.140 eV below the conduction band at the F point. However. the band structure of Ge is a strong function of temperature. strain. alloy composition and dopant concentration. It has been reported that. at about 2% tensile strain. Ge becomes a direct band gap material. indicating the possibility of wide spread applications of Ge-based photonic devices. Alloying Ge with Sn also makes it a direct band gap material. relaxed Ge 1_ySny alloys become direct at 6-10% Sn. In addition. Ge1_s_ ySixSny ternary alloy with two compositional degrees of freedom allows decoupling of the lattice constant and electronic structures simultaneously. Band gap engineering of Ge by controlling strain. alloying composition and dopant concentration has attracted the interest of researchers in materials science. Hence. the knowledge of the compositional. strain. and temperature dependence of the Ge1_x_ySi_ xSny band structure is critical for the design of photonic devices with desired interband transition energy. This dissertation focuses on the optical characterization of the compositional. strain. and temperature dependence of the optical properties of Ge-Si-Sn alloys on Ge/Si substrates using spectroscopic ellipsometry. We use high resolution X-ray diffraction (HRXRD). X-ray reflectivity (XRR) and atomic force microscopy (AFM) to characterize the strain. composition. thickness. surface roughness of the Ge-Si-Sn epilayers on Ge/Si substrates. The temperature dependent thermal expansion coefficient of Ge is larger than Si. Therefore a Ge film. which is relaxed at the growth temperature ( 800 K) on Si substrate. likes to contract more rapidly compared to Si upon cooling down to lower temperatures. and will experience a temperature dependent biaxial tensile stress. We predict the strain dependence the E1 and E 1

  5. Light shifts in atomic Bragg diffraction

    NASA Astrophysics Data System (ADS)

    Giese, E.; Friedrich, A.; Abend, S.; Rasel, E. M.; Schleich, W. P.

    2016-12-01

    Bragg diffraction of an atomic wave packet in a retroreflective geometry with two counterpropagating optical lattices exhibits a light shift induced phase. We show that the temporal shape of the light pulse determines the behavior of this phase shift: In contrast to Raman diffraction, Bragg diffraction with Gaussian pulses leads to a significant suppression of the intrinsic phase shift due to a scaling with the third power of the inverse Doppler frequency. However, for box-shaped laser pulses, the corresponding shift is twice as large as for Raman diffraction. Our results are based on approximate but analytical expressions as well as a numerical integration of the corresponding Schrödinger equation.

  6. Fraunhofer diffraction of light by human enamel.

    PubMed

    O'Brien, W J

    1988-02-01

    Fraunhofer diffraction patterns of human enamel samples were photographed with a helium-neon laser beam (lambda = 633 nm). The first-order diffraction angle was in reasonable agreement with a prediction based upon enamel prisms acting as a two-dimensional grating. These results support the hypothesis that enamel diffracts light because of the periodic structure of enamel prisms with interprismatic spaces, which act as slits.

  7. White-Light Diffraction with a CD

    ERIC Educational Resources Information Center

    Ivanov, Dragia Trifonov; Nikolaev, Stefan

    2010-01-01

    Various wave optics experiments can be carried out using an ordinary compact disc. The CD is suitable for use as a diffraction grating. For instance, a standard CD (700 MB) has 625 lines/mm. In this article, the authors describe two white-light diffraction demonstrations for a large audience, realizable using a CD (as reflection or transmission…

  8. White-Light Diffraction with a CD

    ERIC Educational Resources Information Center

    Ivanov, Dragia Trifonov; Nikolaev, Stefan

    2010-01-01

    Various wave optics experiments can be carried out using an ordinary compact disc. The CD is suitable for use as a diffraction grating. For instance, a standard CD (700 MB) has 625 lines/mm. In this article, the authors describe two white-light diffraction demonstrations for a large audience, realizable using a CD (as reflection or transmission…

  9. Light diffraction by concentrator Fresnel lenses.

    PubMed

    Hornung, Thorsten; Nitz, Peter

    2014-05-05

    Fresnel lenses are widely used in concentrating photovoltaic (CPV) systems as primary optical elements focusing sunlight onto small solar cells or onto entrance apertures of secondary optical elements attached to the solar cells. Calculations using the Young-Maggi-Rubinowicz theory of diffraction yield analytical expressions for the amount of light spilling outside these target areas due to diffraction at the edges of the concentrator Fresnel lenses. Explicit equations are given for the diffraction loss due to planar Fresnel lenses with small prisms and due to arbitrarily shaped Fresnel lenses. Furthermore, the cases of illumination by monochromatic, polychromatic, totally spatially coherent and partially spatially coherent light (e.g. from the solar disc) are treated, resulting in analytical formulae. Examples using realistic values show losses due to diffraction of up to several percent.

  10. Atomic oxygen effects on thin film space coatings studied by spectroscopic ellipsometry, atomic force microscopy, and laser light scattering

    NASA Technical Reports Server (NTRS)

    Synowicki, R. A.; Hale, Jeffrey S.; Woollam, John A.

    1992-01-01

    The University of Nebraska is currently evaluating Low Earth Orbit (LEO) simulation techniques as well as a variety of thin film protective coatings to withstand atomic oxygen (AO) degradation. Both oxygen plasma ashers and an electron cyclotron resonance (ECR) source are being used for LEO simulation. Thin film coatings are characterized by optical techniques including Variable Angle Spectroscopic Ellipsometry, Optical spectrophotometry, and laser light scatterometry. Atomic Force Microscopy (AFM) is also used to characterize surface morphology. Results on diamondlike carbon (DLC) films show that DLC degrades with simulated AO exposure at a rate comparable to Kapton polyimide. Since DLC is not as susceptible to environmental factors such as moisture absorption, it could potentially provide more accurate measurements of AO fluence on short space flights.

  11. Ellipsometry-like analysis of polarization state for micro cracks using stress-induced light scattering method

    NASA Astrophysics Data System (ADS)

    Sakata, Yoshitaro; Terasaki, Nao; Sakai, Kazufumi; Nonaka, Kazuhiro

    2016-03-01

    Fine polishing techniques, such as chemical mechanical polishing (CMP), are important to glass substrate manufacturing. When these techniques involve mechanical interaction in the form of friction between the abrasive and the substrate surface during polishing, latent flaws may form on the product. Fine polishing induced latent flaws in glass substrates may become obvious during a subsequent cleaning process if the glass surface is eroded away by chemical interaction with a cleaning liquid. Thus, latent flaws reduce product yield. A novel technique (the stress-induced light scattering method; SILSM) which was combined with light scattering method and stress effects was proposed for inspecting surface to detect polishing induced latent flaws. This method is able to distinguish between latent flaws and tiny particles on the surface. In this method, an actuator deforms a sample inducing stress effects around the tip of a latent flaw caused by the deformation, which in turn changes the refractive index of the material around the tip of the latent flaw because of the photoelastic effect. A CCD camera detects this changed refractive index as variations in light-scattering intensity. In this study, the changes in reflection coefficients and polarization states after application of stress to a glass substrate were calculated and evaluated qualitatively using Jones matrix-like ellipsometry. As the results, it was shown that change in the polarization states around the tip of latent flaw were evaluated between before and after applied stress, qualitatively.

  12. Light diffraction features in an ordered monolayer of spheres

    NASA Astrophysics Data System (ADS)

    Romanov, S. G.

    2017-07-01

    The structure and optical diffraction properties of monolayers of monodisperse spheres crystallized on transparent dielectric substrates are studied. Two types of diffraction phenomena are considered: surface light diffraction on the lattice of spheres and waveguide resonances in the monolayer plane. For experimental study of these phenomena, optical retroreflection and transmission spectra are measured as functions of the light incidence angle and azimuthal orientation of the incidence plane. The monolayer structures determined by scanning electron microscopy and light diffraction methods are in quantitative agreement. It is concluded that one-dimensional Fraunhofer diffraction is applicable to describe surface diffraction in the hexagonal lattice of spheres. In the case of oblique light incidence, anisotropy of diffraction and transmission spectra depending on the light incidence plane orientation with respect to the sphere lattice and linear polarization of incident light is detected. Waveguide resonances of the planar two-dimensional photonic crystal are approximated within the light diffraction model in the "empty" hexagonal lattice. The best approximation of the waveguide resonance dispersion is achieved using the effective refractive index, depending on the wavelength. Surface diffraction suppression by waveguide resonances of the photonic crystal is demonstrated. Surface diffraction orders are identified as diffraction at singular points of the Brillouin zone of the planar twodimensional photonic crystal.

  13. Hair treatment device for providing dispersed colors by light diffraction

    DOEpatents

    Lamartine, Bruce Carvell; Orler, Bruce E.; Sutton, Richard Matthew Charles; Song, Shuangqi

    2016-01-26

    Hair was coated with polymer-containing fluid and then hot pressed to form a composite of hair and a polymer film imprinted with a nanopattern. Polychromatic light incident on the nanopattern is diffracted into dispersed colored light.

  14. Hair treatment process providing dispersed colors by light diffraction

    DOEpatents

    Lamartine, Bruce Carvell; Orler, E. Bruce; Sutton, Richard Matthew Charles; Song, Shuangqi

    2013-12-17

    Hair was coated with polymer-containing fluid and then hot pressed to form a composite of hair and a polymer film imprinted with a nanopattern. Polychromatic light incident on the nanopattern is diffracted into dispersed colored light.

  15. Hair treatment process providing dispersed colors by light diffraction

    SciTech Connect

    Lamartine, Bruce Carvell; Orler, E. Bruce; Sutton, Richard Matthew Charles; Song, Shuangqi

    2014-11-11

    Hair was coated with polymer-containing fluid and then hot pressed to form a composite of hair and a polymer film imprinted with a nanopattern. Polychromatic light incident on the nanopattern is diffracted into dispersed colored light.

  16. Explication of diffraction lights on an optical imaging system from a Fraunhofer diffraction perspective

    NASA Astrophysics Data System (ADS)

    Ando, Takamasa; Korenaga, Tsuguhiro; Suzuki, Masa-aki

    2012-06-01

    Low-height camera modules are demanded for such applications as cellular phones and vehicles. For designing optical lens, it has widely been recognized that a trade-off exists between reducing the number of lenses and camera resolution. The optical performance of imaging lenses has been improved by diffraction gratings, which have a peculiar inverse dispersion in the wavelength and exhibit the efficacy of correction for chromatic aberration. We can simultaneously reduce the number of lenses and maintain optical resolution using diffraction gratings. However, we have found a generation of striped flare lights under intense light sources that differ from unnecessary order diffraction lights. In this paper, we reveal the generation mechanism of these new striped diffraction lights and suggest a novel structure of diffraction gratings that can decrease them.

  17. Diffraction of entangled particles by light gratings

    SciTech Connect

    Sancho, Pedro

    2015-04-15

    We analyze the diffraction regime of the Kapitza–Dirac effect for particles entangled in momentum. The detection patterns show two-particle interferences. In the single-mode case we identify a discontinuity in the set of joint detection probabilities, associated with the disconnected character of the space of non-separable states. For Gaussian multi-mode states we derive the diffraction patterns, providing an example of the dependence of the light–matter interaction on entanglement. When the particles are identical, we can explore the relation between exchange and entanglement effects. We find a complementary behavior between overlapping and Schmidt’s number. In particular, symmetric entanglement can cancel the exchange effects. - Highlights: • Kapitza–Dirac diffraction of entangled particles shows multiparticle interference. • There is a discontinuity in the set of joint detection patterns of entangled states. • We find a complementary behavior between overlapping and Schmidt’s number. • Symmetric entanglement can cancel the exchange effects.

  18. Fraunhofer Diffraction Patterns from Apertures Illuminated with Nonparallel Light.

    ERIC Educational Resources Information Center

    Klingsporn, Paul E.

    1979-01-01

    Discusses several aspects of Fraunhofer diffraction patterns from apertures illuminated by diverging light. Develops a generalization to apertures of arbitrary shape which shows that the sizes of the pattern are related by a simple scale factor. Uses the Abbe theory of image formation by diffraction to discuss the intensity of illumination of the…

  19. Diffractive optical element with same diffraction pattern for multicolor light-emitting diodes.

    PubMed

    Chen, Mengzhu; Wang, Qixia; Gu, Huarong; Tan, Qiaofeng

    2016-01-01

    The wavelength-division multiplexing technique can be utilized in visible light communication to increase the channel capacity when a multicolor mixed white LED is used as light source. In such an application, the illumination area of LEDs should be invariant to the incident wavelength, so as to decrease interference within the adjacent regions. Diffractive optical elements (DOEs) can be used in the optical transmitter system to shape the diffraction patterns into polygons. However, traditional DOEs illuminated by a multicolor mixed white LED would result into diffraction patterns with unequal sizes. In this paper, a hybrid algorithm which combines particle swarm optimization with a genetic algorithm is proposed for multicolor oriented DOEs design. A DOE is designed and fabricated for blue and red LEDs, and experimental results show that diffraction patterns with rather good uniformity as well as quasi-equal size for red and blue LEDs are obtained.

  20. Anomalous light propagation and diffraction control in waveguide arrays

    NASA Astrophysics Data System (ADS)

    Braeuer, Andreas H.; Streppel, Ulrich; Pertsch, Thomas; Peschel, Ulf; Lederer, Falk L.

    2002-11-01

    The understanding of light propagation primarily derives from studies of isotropic media. The law of refraction predicts that the tilt of a beam traversing an interface between two media will monotonously grow with the angle of incidence. The law of diffraction predicts beam spreading being completely determined by the ratio of wavelength and width, only slightly affected by the refractive index and independent of the tilt. In this paper, we demonstrate anomalies in light refraction and diffraction in evanescently coupled waveguide arrays ('discrete' refraction and diffraction). We have studied the propagation of beams in these arrays. It turned out that refraction and diffraction exhibit strong anomalies as they depend periodically on the initial beam tilt. In contrast to isotropic systems we found that transverse energy transport cannot exceed a certain maximum velocity and that the diffractive spreading depends on the direction of propagation, i.e., by varying the angle of incidence, size and sign of diffraction can be controlled and it can even be arrested. For particular initial tilts the array can undo beam spreading. The experiments were performed on homogeneous arrays of 75 waveguides in an inorganic-organic polymer on thermally oxidized silicon wafers. The 6 cm long samples were fabricated by UV-lithography on 4" wafers. Each waveguide provided low loss single mode waveguiding (<0.5 dB/cm) at λ= 633 nm. The uniform separation of adjacent guides was chosen for efficient evanescent coupling. The theoretical explanation of the measured effects was done based on coupled mode theory.

  1. Coherent diffractive imaging using short wavelength light sources

    NASA Astrophysics Data System (ADS)

    Quiney, H. M.

    2010-07-01

    Techniques that recover images from diffraction data obtained using coherent short-wavelength light sources are currently under active development for applications in nanotechnology and structural biology. In this review, an outline of paraxial optics is provided in a form that is sufficiently general to incorporate the coherence properties and frequency structure of illumination sources used in diffractive imaging applications. The Fourier phase problem is formulated in the context of imaging algorithms that are designed to obtain uniquely-determined phase distributions from measurements of diffraction data. The properties of several iterative phase retrieval algorithms for both coherent and partially-coherent diffractive imaging applications are presented in a unified formalism, together with a brief discussion of a non-iterative technique. Approaches to diffractive imaging based on Fraunhofer and Fresnel diffraction configurations are compared. Applications are described utilising quasi-monochromatic third-generation synchrotron X-ray sources and polychromatic high-harmonic generation table-top soft X-ray sources. The review concludes with a consideration of proposed applications of diffractive imaging approaches to the determination of biomolecular structures from isolated molecules using fourth-generation X-ray free-electron laser sources.

  2. Light bullets by synthetic diffraction-dispersion matching.

    PubMed

    Lobanov, Valery E; Kartashov, Yaroslav V; Torner, Lluis

    2010-07-16

    We put forward a new approach to generate stable, fully three-dimensional light bullets, which is based on the matching of the intrinsic material dispersion with a suitable effective diffraction. The matching is achieved in adequate waveguide arrays whose refractive index is periodically modulated along the direction of light propagation. We show that by using nonconventional, out-of-phase longitudinal modulation of the refractive index of neighboring channels, it is possible to tune the effective diffraction to match the intrinsic material group velocity dispersion. Three-dimensional light bullets are shown to form at reduced energy levels, in settings where the dispersion would be far too weak to generate bullets in the absence of array.

  3. Light Diffraction by Large Amplitude Ultrasonic Waves in Liquids

    NASA Technical Reports Server (NTRS)

    Adler, Laszlo; Cantrell, John H.; Yost, William T.

    2016-01-01

    Light diffraction from ultrasound, which can be used to investigate nonlinear acoustic phenomena in liquids, is reported for wave amplitudes larger than that typically reported in the literature. Large amplitude waves result in waveform distortion due to the nonlinearity of the medium that generates harmonics and produces asymmetries in the light diffraction pattern. For standing waves with amplitudes above a threshold value, subharmonics are generated in addition to the harmonics and produce additional diffraction orders of the incident light. With increasing drive amplitude above the threshold a cascade of period-doubling subharmonics are generated, terminating in a region characterized by a random, incoherent (chaotic) diffraction pattern. To explain the experimental results a toy model is introduced, which is derived from traveling wave solutions of the nonlinear wave equation corresponding to the fundamental and second harmonic standing waves. The toy model reduces the nonlinear partial differential equation to a mathematically more tractable nonlinear ordinary differential equation. The model predicts the experimentally observed cascade of period-doubling subharmonics terminating in chaos that occurs with increasing drive amplitudes above the threshold value. The calculated threshold amplitude is consistent with the value estimated from the experimental data.

  4. Switchable zero order diffraction gratings as light valves

    NASA Astrophysics Data System (ADS)

    Melngailis, J.

    1983-06-01

    The motivation of this work is to produce line-addressable arrays of independently switchable light valves for flat-panel video displays. In addition, such light valves would be useful as spatial light modulators in optical signal processing. The principle of the light valves is based on the switching of the zero order of diffraction. Two gratings are fabricated face-to-face and displaced with respect to one another by half of one period. The displacement may be produced by using the strong piezoelectric properties of PVF2 or, alternatively, by using electrostatic forces. The goal of this project is to build a fast, lockable, miniature light valve which is compatible with fabrication into arrays.

  5. Hair treatment process providing dispersed colors by light diffraction

    SciTech Connect

    Sutton, Richard Matthew Charles; Lamartine, Bruce Carvell; Orler, E. Bruce; Song, Shuangqi

    2015-12-22

    A hair treatment process for providing dispersed colors by light diffraction including (a) coating the hair with a material comprising a polymer, (b) pressing the hair with a pressing device including one or more surfaces, and (c) forming a secondary nanostructured surface pattern on the hair that is complementary to the primary nanostructured surface pattern on the one or more surfaces of the pressing device. The secondary nanostructured surface pattern diffracts light into dispersed colors that are visible on the hair. The section of the hair is pressed with the pressing device for from about 1 to 55 seconds. The polymer has a glass transition temperature from about 55.degree. C. to about 90.degree. C. The one or more surfaces include a primary nanostructured surface pattern.

  6. White-light diffraction tomography of unlabelled live cells

    NASA Astrophysics Data System (ADS)

    Kim, Taewoo; Zhou, Renjie; Mir, Mustafa; Babacan, S. Derin; Carney, P. Scott; Goddard, Lynford L.; Popescu, Gabriel

    2014-03-01

    We present a technique called white-light diffraction tomography (WDT) for imaging microscopic transparent objects such as live unlabelled cells. The approach extends diffraction tomography to white-light illumination and imaging rather than scattering plane measurements. Our experiments were performed using a conventional phase contrast microscope upgraded with a module to measure quantitative phase images. The axial dimension of the object was reconstructed by scanning the focus through the object and acquiring a stack of phase-resolved images. We reconstructed the three-dimensional structures of live, unlabelled, red blood cells and compared the results with confocal and scanning electron microscopy images. The 350 nm transverse and 900 nm axial resolution achieved reveals subcellular structures at high resolution in Escherichia coli cells. The results establish WDT as a means for measuring three-dimensional subcellular structures in a non-invasive and label-free manner.

  7. Optical fiber alignment using cleaved-edge diffracted light

    NASA Astrophysics Data System (ADS)

    Brun, Louis C.; Bergeron, Patrick; Duguay, Michel A.; Ouellette, Francois; Tetu, Michel

    1993-08-01

    We describe a simple technique for aligning optical fibers prior to fusion splicing. The technique relies on the fact that well-cleaved fiber ends have extremely sharp edges. By making the narrow pencil of light emerging from one fiber scan laterally over the entrance face of a second fiber, and by monitoring the light diffracted past its sharp edges, we can locate precisely the geometric center of the output fiber. With this technique, we have aligned fiber cores with a mean lateral offset of 0.81 micrometers , the major part of this offset caused by the eccentricity of the core relative to the cladding's circular perimeter.

  8. Achromatic correction of diffractive dispersion in white light SLM imaging.

    PubMed

    Bouchal, Zdeněk; Chlup, Vladimír; Celechovský, Radek; Bouchal, Petr; Nistor, Ioan Cristian

    2014-05-19

    In contemporary optics, the spatial light modulator (SLM) is effectively used as a flexible optoelectronic device playing the key role in a number of experiments of science and technology. Its operation is optimal when using almost monochromatic light but an extremely strong diffractive dispersion occurs when white light is applied. In this paper, the design concepts are proposed resulting in optimization and implementation of a refractive corrector cooperating with the SLM. The corrector maintains the operation of the SLM unchanged for the central wavelength of light and ensures an achromatic dispersion compensation throughout the visible region in applications based on a lens-pattern formation. A significant improvement of the imaging performance of the achromatic SLM was proved by the computer simulation and measurement of the chromatic focal shift and the image contrast of the resolution target.

  9. Enhanced light absorption of solar cells and photodetectors by diffraction

    DOEpatents

    Zaidi, Saleem H.; Gee, James M.

    2005-02-22

    Enhanced light absorption of solar cells and photodetectors by diffraction is described. Triangular, rectangular, and blazed subwavelength periodic structures are shown to improve performance of solar cells. Surface reflection can be tailored for either broadband, or narrow-band spectral absorption. Enhanced absorption is achieved by efficient optical coupling into obliquely propagating transmitted diffraction orders. Subwavelength one-dimensional structures are designed for polarization-dependent, wavelength-selective absorption in solar cells and photodetectors, while two-dimensional structures are designed for polarization-independent, wavelength-selective absorption therein. Suitable one and two-dimensional subwavelength periodic structures can also be designed for broadband spectral absorption in solar cells and photodetectors. If reactive ion etching (RIE) processes are used to form the grating, RIE-induced surface damage in subwavelength structures can be repaired by forming junctions using ion implantation methods. RIE-induced surface damage can also be removed by post RIE wet-chemical etching treatments.

  10. Laue diffraction protein crystallography at the National Synchrotron Light Source

    SciTech Connect

    Getzoff, E.D.; McRee, D. ); Jones, K.W.; Spanne, P.; Sweet, R.M. ); Moffat, K.; Ng, K.; Rivers, M.L.; Schildkamp, W.; Teng, T.Y. ); Singer, P.T.; Westbrook, E.M. )

    1992-01-01

    A new facility for the study of protein crystal structure using Laue diffraction has been established at the X26 beam line of the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. The characteristics of the beam line and diffraction apparatus are described. Selected results of some of the initial experiments are discussed briefly by beam line users to illustrate the scope of the experimental program. Because the Laue method permits the recording of large data sets in a single shot, one goal in establishing this facility has been to develop the means to study time-resolved structures within protein crystals. Systems being studied include: the reactions catalyzed by trypsin; photolysis of carbonmonoxy myoglobin; and the photocycle of photoactive yellow protein.

  11. Laue diffraction protein crystallography at the National Synchrotron Light Source

    SciTech Connect

    Getzoff, E.D.; McRee, D.; Jones, K.W.; Spanne, P.; Sweet, R.M.; Moffat, K.; Ng, K.; Rivers, M.L.; Schildkamp, W.; Teng, T.Y.; Singer, P.T.; Westbrook, E.M.

    1992-12-31

    A new facility for the study of protein crystal structure using Laue diffraction has been established at the X26 beam line of the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. The characteristics of the beam line and diffraction apparatus are described. Selected results of some of the initial experiments are discussed briefly by beam line users to illustrate the scope of the experimental program. Because the Laue method permits the recording of large data sets in a single shot, one goal in establishing this facility has been to develop the means to study time-resolved structures within protein crystals. Systems being studied include: the reactions catalyzed by trypsin; photolysis of carbonmonoxy myoglobin; and the photocycle of photoactive yellow protein.

  12. Microscopic theory of diffraction of light from a small hole

    NASA Astrophysics Data System (ADS)

    Jung, Jesper; Keller, Ole

    2014-10-01

    On the basis of the Maxwell-Lorentz local-field equations and nonlocal linear response theory, a self-consistent microscopic Green function theory of diffraction of light from a single hole in a thin and plane metallic screen is established. By subtracting the scattering of identical incident fields from screens with and without a hole, a causal effective optical aperture response tensor is introduced. An approximate expression is derived for the aperture response tensor in the limit where the screen behaves like an electric-dipole absorber and radiator. In this limit the internal electron dynamics is that of a quantum well. For a screen so thin that its bound electron motion can be described by a single quantum level, a approach for a quantum mechanical calculation of the aperture response tensor is presented. When the linear dimensions of the hole become sufficiently small the so-called aperture field, defined as the difference between the prevailing electric field with and that without a hole, becomes identical to the field from an incident-field-induced electric dipole with anisotropic linear polarizability. Our theory is formulated in such a manner that preknowledge only of (i) the incident electromagnetic field and (ii) the light-unperturbed optical electron properties (the microscopic conductivity tensor) of the screen with the geometrically given hole is needed. Since the microscopic theory allows for the presence of an (oscillating) component of the sheet current density perpendicular to the plane of the screen, a generalization of (i) the standard jump conditions of the field across the sheet and (ii) the reflection symmetries of the various fields in the plane of the screen is worked out. As our theory deviates radically from the approach of all classical diffraction theories, which are based on the macroscopic Maxwell equations and some kind of pheno-menological expression for the screen conductivity σ (often just σ →∞), we give a brief review of

  13. Super-resolution optical telescopes with local light diffraction shrinkage.

    PubMed

    Wang, Changtao; Tang, Dongliang; Wang, Yanqin; Zhao, Zeyu; Wang, Jiong; Pu, Mingbo; Zhang, Yudong; Yan, Wei; Gao, Ping; Luo, Xiangang

    2015-12-18

    Suffering from giant size of objective lenses and infeasible manipulations of distant targets, telescopes could not seek helps from present super-resolution imaging, such as scanning near-field optical microscopy, perfect lens and stimulated emission depletion microscopy. In this paper, local light diffraction shrinkage associated with optical super-oscillatory phenomenon is proposed for real-time and optically restoring super-resolution imaging information in a telescope system. It is found that fine target features concealed in diffraction-limited optical images of a telescope could be observed in a small local field of view, benefiting from a relayed metasurface-based super-oscillatory imaging optics in which some local Fourier components beyond the cut-off frequency of telescope could be restored. As experimental examples, a minimal resolution to 0.55 of Rayleigh criterion is obtained, and imaging complex targets and large targets by superimposing multiple local fields of views are demonstrated as well. This investigation provides an access for real-time, incoherent and super-resolution telescopes without the manipulation of distant targets. More importantly, it gives counterintuitive evidence to the common knowledge that relayed optics could not deliver more imaging details than objective systems.

  14. Super-resolution optical telescopes with local light diffraction shrinkage

    NASA Astrophysics Data System (ADS)

    Wang, Changtao; Tang, Dongliang; Wang, Yanqin; Zhao, Zeyu; Wang, Jiong; Pu, Mingbo; Zhang, Yudong; Yan, Wei; Gao, Ping; Luo, Xiangang

    2015-12-01

    Suffering from giant size of objective lenses and infeasible manipulations of distant targets, telescopes could not seek helps from present super-resolution imaging, such as scanning near-field optical microscopy, perfect lens and stimulated emission depletion microscopy. In this paper, local light diffraction shrinkage associated with optical super-oscillatory phenomenon is proposed for real-time and optically restoring super-resolution imaging information in a telescope system. It is found that fine target features concealed in diffraction-limited optical images of a telescope could be observed in a small local field of view, benefiting from a relayed metasurface-based super-oscillatory imaging optics in which some local Fourier components beyond the cut-off frequency of telescope could be restored. As experimental examples, a minimal resolution to 0.55 of Rayleigh criterion is obtained, and imaging complex targets and large targets by superimposing multiple local fields of views are demonstrated as well. This investigation provides an access for real-time, incoherent and super-resolution telescopes without the manipulation of distant targets. More importantly, it gives counterintuitive evidence to the common knowledge that relayed optics could not deliver more imaging details than objective systems.

  15. Super-resolution optical telescopes with local light diffraction shrinkage

    PubMed Central

    Wang, Changtao; Tang, Dongliang; Wang, Yanqin; Zhao, Zeyu; Wang, Jiong; Pu, Mingbo; Zhang, Yudong; Yan, Wei; Gao, Ping; Luo, Xiangang

    2015-01-01

    Suffering from giant size of objective lenses and infeasible manipulations of distant targets, telescopes could not seek helps from present super-resolution imaging, such as scanning near-field optical microscopy, perfect lens and stimulated emission depletion microscopy. In this paper, local light diffraction shrinkage associated with optical super-oscillatory phenomenon is proposed for real-time and optically restoring super-resolution imaging information in a telescope system. It is found that fine target features concealed in diffraction-limited optical images of a telescope could be observed in a small local field of view, benefiting from a relayed metasurface-based super-oscillatory imaging optics in which some local Fourier components beyond the cut-off frequency of telescope could be restored. As experimental examples, a minimal resolution to 0.55 of Rayleigh criterion is obtained, and imaging complex targets and large targets by superimposing multiple local fields of views are demonstrated as well. This investigation provides an access for real-time, incoherent and super-resolution telescopes without the manipulation of distant targets. More importantly, it gives counterintuitive evidence to the common knowledge that relayed optics could not deliver more imaging details than objective systems. PMID:26677820

  16. Anomalous behaviors of the Fraunhofer diffraction patterns for a class of partially coherent light.

    PubMed

    Pu, Jixiong; Nemoto, Shojiro

    2003-02-24

    In this paper, we investigate the Fraunhofer diffraction of a class of partially coherent light diffracted by a circular aperture. It is shown that by the illumination of partially coherent light of the special spatial correlation function, the anomalous behaviors of the diffraction patterns are found. We find that the decrease of the spatial coherence of the light in the aperture leads to the drastic changes of the diffraction pattern. Specifically, when the light in the aperture is fully coherent, the diffraction pattern is just an Airy disc. However, as the coherence decreases, the diffraction pattern becomes an annulus, and the radius of the annulus increases with the decrease of the coherence. Flattened annuli can be achieved, when the parameters characterizing the correlation of the partially coherent light are chosen with suitable values. Potential applications of modulating the coherence to achieve desired diffraction patterns are discussed.

  17. Numerical simulation of Fresnel and Fraunhofer diffractions of monochromatic and white light

    NASA Astrophysics Data System (ADS)

    Qian, Heng; Lin, Wenbin; Qi, Xiexing

    2016-08-01

    We describe a computer simulation technique for generating the monochromatic light diffraction from arbitrary apertures. For the Fresnel diffraction of rectangular and circular apertures, a simple form of equation for the light intensity distribution is derived. A method for displaying the color of monochromatic light on the monitor is presented. On this basis, we implement the diffraction simulation of white light formed via mixing three monochromatic lights of λ=700,546.1,435.8 nm with the same ratio in the RGB color space of CIE1931 system.

  18. Forward light scattering for arbitrary sharp-edged convex crystals in Fraunhofer and anomalous diffraction approximations.

    PubMed

    Heffels, C; Heitzmann, D; Hirleman, E D; Scarlett, B

    1995-10-01

    Fraunhofer diffraction is a well-known physical model for describing forward light scattering from opaque particles much larger than the wavelength of the light. Analytical expressions exist for diffraction from circular- or rectangular-shaped apertures. An expression is derived for diffraction by apertures of a general polygonal shape. From this expression the exact solution for anomalous diffraction by arbitrary convex crystals is calculated. These expressions are useful in characterizing crystal size and shape, by laser diffraction instruments, when measured in a solution.

  19. Diffraction-dependent spin splitting in spin Hall effect of light on reflection.

    PubMed

    Qiu, Xiaodong; Xie, Linguo; Qiu, Jiangdong; Zhang, Zhiyou; Du, Jinglei; Gao, Fuhua

    2015-07-27

    We report on a diffraction-dependent spin splitting of the paraxial Gaussian light beams on reflection theoretically and experimentally. In the case of horizontal incident polarization, the spin splitting is proportional to the diffraction length of light beams near the Brewster angle. However, the spin splitting is nearly independent with the diffraction length for the vertical incident polarization. By means of the angular spectrum theory, we find that the diffraction-dependent spin splitting is attributed to the first order expansion term of the reflection coefficients with respect to the transverse wave-vector which is closely related to the diffraction length.

  20. Determination of Particle Size by Diffraction of Light

    ERIC Educational Resources Information Center

    Rinard, Phillip M.

    1974-01-01

    Describes a simplified diffraction experiment offered in a workshop with the purpose of illustrating to high school students the relation of science to society. The radii determined for cigarette smoke particles range from 0.2 to 0.5 micrometer in this experiment. Included is a description of the diffraction theory. (CC)

  1. Teaching Diffraction of Light and Electrons: Classroom Analogies to Classic Experiments

    ERIC Educational Resources Information Center

    Velentzas, Athanasios

    2014-01-01

    Diffraction and interference are phenomena that demonstrate the wave nature of light and of particles. Experiments relating to the diffraction/interference of light can easily be carried out in an educational lab, but it may be impossible to perform experiments involving electrons because of the lack of specialized equipment needed for such…

  2. Teaching Diffraction of Light and Electrons: Classroom Analogies to Classic Experiments

    ERIC Educational Resources Information Center

    Velentzas, Athanasios

    2014-01-01

    Diffraction and interference are phenomena that demonstrate the wave nature of light and of particles. Experiments relating to the diffraction/interference of light can easily be carried out in an educational lab, but it may be impossible to perform experiments involving electrons because of the lack of specialized equipment needed for such…

  3. Polarization effects in the diffraction of light by a planar chiral structure

    SciTech Connect

    Prosvirnin, S.L.; Zheludev, N.I.

    2005-03-01

    We analyze polarization changes of light diffracted on a planar chiral array from the standpoint of the Lorentz reciprocity lemma and find biorthogonality in the polarization eigenstates for waves diffracting though the grating in the opposite direction. Both reciprocal and nonreciprocal components in the polarization azimuth rotation of the diffracted light are identified. The structural chirality of the array arrangement and the chirality of individual elements of the array give rise to polarization effects.

  4. Light diffraction by a particle on an optically smooth surface.

    PubMed

    Johnson, B R

    1997-01-01

    The differential cross section for radiation scattered by a particle that is large compared to the wavelength, and resting on an optically smooth surface, is characterized by an intense, narrow peak in the direction of the reflected beam. This peak is shown to be due mainly to Fraunhofer diffraction by the overlapping projections of the particle and its image on a plane perpendicular to the reflected beam. Results calculated with this simple diffraction theory are compared with accurate results calculated by the multipole expansion method. Simple analytic formulas are derived that characterize the width and height of the central diffraction peak.

  5. Diffractive element design for generating multi-channel structured light field

    NASA Astrophysics Data System (ADS)

    Wang, Jia-Zhou; Pang, Hui; Zhang, Man; Shi, Li-Fang; Cao, A.-Xiu; Deng, Qi-Ling; Hu, Song

    2016-10-01

    With the advantages of small structure and high efficiency, the diffractive element is widely used in the construction of a structured light 3D measurement system. But the working wavelength of diffraction element is single, and the light field generated by the diffraction element is only one channel. We make the original single channel into three channels, so as to achieve from the serial algorithm to parallel algorithm to improve the measurement speed. Based on the lattice light field and the design method of multi wavelength diffraction elements, and in the premise of ensuring the number of points, the traditional lattice points of light field are divided into three channels. These channels are regarded as the target fields, and the diffraction element for generating color structure light field is designed.

  6. Enhanced light extraction efficiency of OLEDs with quasiperiodic diffraction grating layer.

    PubMed

    Lim, Tae-Bin; Cho, Kwan Hyun; Kim, Yong-Hoon; Jeong, Yong-Cheol

    2016-08-08

    We presented enhanced light extraction efficiency of organic light emitting diodes (OLEDs) cells with a nano-sized diffraction grating layer. Various diffraction gratings of different morphologies including linear, cubic, hexagonal and quasiperiodic patterns were fabricated by multiplexing light interference exposure on an azobenzene thin film. The effect of diffraction grating layer on device performances including luminous properties and quantum efficiency was investigated. In contrast to periodic grating patterns, the quasiperiodic structures leading broadband light extraction resulted in improved external quantum efficiency and power efficiency by 73% and 63%, respectively, compared to conventional OLED with flat surface of glass substrate.

  7. Fine structures in the light diffraction pattern of striated muscle.

    PubMed

    Leung, A F

    1984-10-01

    Single skeletal muscle fibres of frog were illuminated with a He-Ne, argon-ion or rhodamine 6G dye laser. The fine structures lying within the diffraction columns moved parallel to the fibre axis without changing their pattern when either the wavelength or the incident angle of the laser beam was varied, or when the fibre was stretched slightly. However, their pattern remained nearly constant when the fibre was submerged in hypotonic or hypertonic solution. As the illumination of about 1 mm or 0.1 mm width scanned along the length of the fibre, new structures emerged while others faded away giving rise to the notion that the diffraction columns were moving in the direction of the scan. A decrease in the illumination width caused the structures lying on the periphery of the diffraction column to disappear and the width of the remaining structures to increase. Measurements rule out the existence of large diffraction planes in these muscles. In addition, they indicate that the fine structures come from the diffraction of the whole rather than independent components of the illuminated volume. The origin of the fine structures is explained by two diffraction models.

  8. Efficient IR Transmission Diffraction Grating for Circularly Polarized Light

    NASA Technical Reports Server (NTRS)

    Cole, Helen; Chambers, Diana

    1999-01-01

    Numerical methods, using rigorous coupled wave theory, are used to design rectangular relief diffraction gratings for an infrared application which requires comparable first order efficiencies in the TE and TM polarization states. The depth, period, and fill factor of the grating are varied to identify optimal two level binary lamellar grating profiles which predict efficiencies for individual TM and TE polarizations above 75 percent, while keeping the difference between the two efficiencies within 10 percent. The application at hand is a rotating, transmissive diffractive scanner for space-based coherent lidar. The operating wavelength is 2.0 microns. A collimated, circularly polarized beam is incident on the diffractive scanner at the Bragg angle; 30 and 45 degree beam deflection angles being studied. Fused silica is the substrate material of choice. Selected designs are fabricated on 3 inch fused silica substrates using lithographic methods. The performance of the test pieces is measured and compared to theoretical predictions.

  9. Jet Fuel Thermal Stability Investigations Using Ellipsometry

    NASA Technical Reports Server (NTRS)

    Nash, Leigh; Vasu, Subith S.; Klettlinger, Jennifer Lindsey

    2017-01-01

    Jet fuels are typically used for endothermic cooling in practical engines where their thermal stability is very important. In this work the thermal stability of Sasol IPK (a synthetic jet fuel) with varying levels of naphthalene has been studied on stainless steel substrates using spectroscopic ellipsometry in the temperature range 385-400 K. Ellipsometry is an optical technique that measures the changes in a light beam’s polarization and intensity after it reflects off of a thin film to determine the film’s thickness and optical properties. All of the tubes used were rated as thermally unstable by the color standard portion of the Jet Fuel Thermal Oxidation Test, and this was confirmed by the deposit thicknesses observed using ellipsometry. A new amorphous model on a stainless steel substrate was used to model the data and obtain the results. It was observed that, as would be expected, increasing the temperature of the tube increased the overall deposit amount for a constant concentration of naphthalene. The repeatability of these measurements was assessed using multiple trials of the same fuel at 385 K. Lastly, the effect of increasing the naphthalene concentration in the fuel at a constant temperature was found to increase the deposit thickness.In conclusion, ellipsometry was used to investigate the thermal stability of jet fuels on stainless steel substrate. The effects of increasing temperature and addition of naphthalene on stainless steel tubes with Sasol IPK fuel were investigated. It was found, as expected, that increasing temperature lead to an increase in deposit thickness. It wasAmerican Institute of Aeronautics and Astronautics6also found that increasing amounts of naphthalene increased the maximum deposit thickness. The repeatability of these measurements was investigated using multiple tests at the same conditions. The present work provides as a better quantitative tool compared to the widely used JFTOT technique. Future work will expand on the

  10. Diffracted light from latent images in photoresist for exposure control

    DOEpatents

    Bishop, Kenneth P.; Brueck, Steven R. J.; Gaspar, Susan M.; Hickman, Kirt C.; McNeil, John R.; Naqvi, S. Sohail H.; Stallard, Brian R.; Tipton, Gary D.

    1997-01-01

    In microelectronics manufacturing, an arrangement for monitoring and control of exposure of an undeveloped photosensitive layer on a structure susceptible to variations in optical properties in order to attain the desired critical dimension for the pattern to be developed in the photosensitive layer. This is done by ascertaining the intensities for one or more respective orders of diffracted power for an incident beam of radiation corresponding to the desired critical dimension for the photosensitive layer as a function of exposure time and optical properties of the structure, illuminating the photosensitive layer with a beam of radiation of one or more frequencies to which the photosensitive layer is not exposure-sensitive, and monitoring the intensities of the orders of diffracted radiation due to said illumination including at least the first order of diffracted radiation thereof, such that when said predetermined intensities for the diffracted orders are reached during said illumination of photosensitive layer, it is known that a pattern having at least approximately the desired critical dimension can be developed on the photosensitive layer.

  11. Doppler shift generated by a moving diffraction grating under incidence by polychromatic diffuse light.

    PubMed

    Dossou, Kokou B

    2016-05-20

    We consider the spectral response of moving diffraction gratings, in which the incident light extends over a broad angular range and where the diffracted light is observed from a specific angle. We show that the dispersion relation between the frequency perceived by an observer who is looking at a moving grating and the incident frequency can exhibit some unique features, such as a flat band (i.e., a local minimum). An observer can see the light diffracted into a nonspecular diffraction order from a multitude of incident light rays, and the angle of incidence of each ray is frequency dependent; as a consequence, when the grating is moving, each incident ray experiences a Doppler shift in frequency that depends on its angle of incidence. We find that remarkable features appear near a Wood anomaly where the angle of incidence, for a given diffraction angle, can change very quickly with frequency. This means that light of multiple frequencies and incident from multiple angles can be mixed by the motion of the grating into the same diffracted ray and their frequencies can be compressed into a narrower range. The existence of a flat band means that a moving grating can be used as a device to increase the intensity of the perceived diffracted light due to spectral compression. The properties of a grating in motion in sunlight can also be relevant to the study of naturally occurring gratings which are typically in oscillatory motion.

  12. Microscopic ellipsometry image of microspheres on a substrate

    NASA Astrophysics Data System (ADS)

    Hsiao, F.-C.; Chen, Yu-Da; Ngo, Trong H. B.; Xie, Huai-Yi; Chang, Yia-Chung

    2015-08-01

    We performed experimental measurements and theoretical simulation based on an efficient half-space Green's function method to investigate the diffraction patterns of light scattering from silicon and ZnO microspheres on a substrate. The microscopic ellipsometry image for s- and p-polarized reflectance and their phase difference (Rs, Rp, and Δ) was taken by a modified Optrel MULTISKOP system with rotating compensator configuration for various angles of incidence and wavelengths ranging from 450nm to 750nm. An 80X objective was used and the pixel size for our image is around 200nm. The images obtained display clear diffraction patterns, which is analyzed by an efficient full-wave simulation based on half-space Green's function method. The near-field distributions obtained theoretically are then converted to far-field images by filtering out the evanescent waves and propagating waves which cannot reach the objective. The experimental results are then compared with simulated images to gain better understanding of the image patterns. Some prominent peaks are observed and attributed to resonances related to whispering gallery modes.

  13. Light scattering by red blood cells in ektacytometry: Fraunhofer versus anomalous diffraction.

    PubMed

    Streekstra, G J; Hoekstra, A G; Nijhof, E J; Heethaar, R M

    1993-05-01

    In the present literature on ektacytometry, small angle light scattering by ellipsoidal red blood cells is commonly approximated by Fraunhofer diffraction. Calculations on a sphere with the size and relative refractive index of a red cell, however, show that Fraunhofer diffraction deviates significantly from exact Mie theory. Anomalous diffraction is found to be a much better approximation. The anomalous diffraction theory is used to calculate the intensity distribution of the light scattered by an ellipsoidally deformed red blood cell. The derived expression shows that the ellipticity of isointensity curves in forward scattered light are equal to the ellipticity of the red blood cell. The theoretical expression is fitted to the intensity patterns measured with an ektacytometer. For the small observation angles used in ektacytometry, the experimental results confirm the validity of the anomalous diffraction approach.

  14. Verification of the Uncertainty Principle by Using Diffraction of Light Waves

    ERIC Educational Resources Information Center

    Nikolic, D.; Nesic, Lj

    2011-01-01

    We described a simple idea for experimental verification of the uncertainty principle for light waves. We used a single-slit diffraction of a laser beam for measuring the angular width of zero-order diffraction maximum and obtained the corresponding wave number uncertainty. We will assume that the uncertainty in position is the slit width. For the…

  15. Verification of the Uncertainty Principle by Using Diffraction of Light Waves

    ERIC Educational Resources Information Center

    Nikolic, D.; Nesic, Lj

    2011-01-01

    We described a simple idea for experimental verification of the uncertainty principle for light waves. We used a single-slit diffraction of a laser beam for measuring the angular width of zero-order diffraction maximum and obtained the corresponding wave number uncertainty. We will assume that the uncertainty in position is the slit width. For the…

  16. Bragg diffraction of light from ultrasound in cubic centrosymmetric crystals in an external electric field

    SciTech Connect

    Kurilkina, S.N.

    1995-03-01

    Special features of noncollinear Bragg diffraction of light from ultrasound in centrosymmetric cubic crystals placed in an external electric field are considered. Particular cases of acousto-electro-optical interaction on (quasi-)longitudinal and (quasi-)transverse acoustic waves propagating the (001) and (110) planes are analyzed. The dependence of diffracted light energy characteristics on photoelastic and electro-optical parameters of a cubic centrosymmetric crystal, as well as external field strength and orientation, is determined. 11 refs., 2 figs.

  17. Diffraction calculation of occultation light curves in the presence of an isothermal atmosphere

    NASA Technical Reports Server (NTRS)

    French, R. G.; Gierasch, P. J.

    1976-01-01

    From diffraction theory, light curves are calculated for stellar occultations by a planetary body with an isothermal atmosphere. The character of the resulting curves is determined by the scale height H, the Fresnel zone size l, the surface atmospheric refractivity, and the planetary radius. An exact general solution and two approximations are presented which are valid when H is much greater than l. The importance is assessed of accounting for diffraction effects of the limb when deducing atmospheric parameters from occultation light curves

  18. Pixel Detectors For Diffraction Experiments At The Swiss Light Source

    SciTech Connect

    Huelsen, G.; Eikenberry, E.F.; Schmitt, B.; Schulze-Briese, C.; Tomizaki, T.; Stampanoni, M.; Willmott, P.; Patterson, B.; Broennimann, Ch.; Horisberger, R.; Toyokawa, H.; Borchert, G. L.

    2004-05-12

    The PILATUS detector (Pixel Apparatus for the SLS) is a large, quantum-limited area X-ray detector for protein crystallography which is currently under construction. Its basic units are modules with 16 CMOS chips bump-bonded to a large, continuously sensitive silicon sensor with 157x366 pixels of 217x217 {mu}m2, leading to an active area of 34x80 mm2. With a counting circuit in each pixel, X-rays are detected in single photon counting mode, leading to excellent, noise-free data. The main properties of the detector are an energy range of 6 to 30 keV, no back-ground due to leakage current or readout-noise, fast read-out time of 6.7 ms, a rate/pixel >104/s and a PSF of one pixel. PILATUS detectors are installed at the SLS X06SA protein crystallography beamline, and at both the surface diffraction (SD) station and the radiography and tomography (XTM) station of beamline X04SA. The detectors are operated at room temperature and thus are very easy to use. Experiments benefit from the ability to detect very weak diffraction spots with high precision. At the SD station and at the XTM station, which is equipped with a Bragg magnifier, diffraction, radiography and tomography experiments showed promising results. At beamline X06SA, a three-module array (1120x157 pixels) with a readout time of 6.7 ms was tested. This system was used to collect fine phi-sliced protein crystal data in continuous sample rotation mode in which the crystal was continuously rotated with a slow angular velocity of 0.04 deg./s without any shutter operation. Exposure time per frame ranged from 100 ms to a few seconds, depending on the crystal. These initial experiments show the potential of this method.

  19. Pixel Detectors For Diffraction Experiments At The Swiss Light Source

    NASA Astrophysics Data System (ADS)

    Hülsen, G.; Eikenberry, E. F.; Horisberger, R.; Schmitt, B.; Schulze-Briese, C.; Tomizaki, T.; Toyokawa, H.; Stampanoni, M.; Borchert, G. L.; Willmott, P.; Patterson, B.; Brönnimann, Ch.

    2004-05-01

    The PILATUS detector (Pixel Apparatus for the SLS) is a large, quantum-limited area X-ray detector for protein crystallography which is currently under construction. Its basic units are modules with 16 CMOS chips bump-bonded to a large, continuously sensitive silicon sensor with 157×366 pixels of 217×217 μm2, leading to an active area of 34×80 mm2. With a counting circuit in each pixel, X-rays are detected in single photon counting mode, leading to excellent, noise-free data. The main properties of the detector are an energy range of 6 to 30 keV, no back-ground due to leakage current or readout-noise, fast read-out time of 6.7 ms, a rate/pixel >104/s and a PSF of one pixel. PILATUS detectors are installed at the SLS X06SA protein crystallography beamline, and at both the surface diffraction (SD) station and the radiography and tomography (XTM) station of beamline X04SA. The detectors are operated at room temperature and thus are very easy to use. Experiments benefit from the ability to detect very weak diffraction spots with high precision. At the SD station and at the XTM station, which is equipped with a Bragg magnifier, diffraction, radiography and tomography experiments showed promising results. At beamline X06SA, a three-module array (1120×157 pixels) with a readout time of 6.7 ms was tested. This system was used to collect fine phi-sliced protein crystal data in continuous sample rotation mode in which the crystal was continuously rotated with a slow angular velocity of 0.04 °/s without any shutter operation. Exposure time per frame ranged from 100 ms to a few seconds, depending on the crystal. These initial experiments show the potential of this method.

  20. Diamond anvil cell radial x-ray diffraction program at the National Synchrotron Light Source.

    PubMed

    Hu, J Z; Mao, H K; Shu, J F; Guo, Q Z; Liu, H Z

    2006-06-28

    During the past decade, the radial x-ray diffraction method using a diamond anvil cell (DAC) has been developed at the X17C beamline of the National Synchrotron Light Source. The detailed experimental procedure used with energy dispersive x-ray diffraction is described. The advantages and limitations of using the energy dispersive method for DAC radial diffraction studies are also discussed. The results for FeO at 135 GPa and other radial diffraction experiments performed at X17C are discussed in this report.

  1. Inverse problem solution in ellipsometry

    NASA Astrophysics Data System (ADS)

    Zabashta, Lubov A.; Zabashta, Oleg I.

    1995-11-01

    Interactive graphic system 'ELLA' is described which is an integrated program packet for reverse problem solution in ellipsometry. The solutions stable to experimental errors are found by two algorithms: a simplex method under constraints and a regularizing iteration method. A developed graphic procedure kit includes display of graphic surface layers, their optical parameters, and all main results of intermediate calculations. Specialized graphic input functions allow us to change the parameters of a chosen solution method, the basic data, to enter new additional information, etc. On the examples of model structure of GaAs-oxide MAI capabilities in ellipsometry for determination of multilayer structure optical parameters are studied.

  2. Light coupling into an optical microcantilever by an embedded diffraction grating.

    PubMed

    Zinoviev, K; Dominguez, C; Plaza, J A; Cadarso, V; Lechuga, L M

    2006-01-10

    By measuring the excitation efficiency of an optical waveguide on a diffraction grating one can accurately register the changes in the incidence angle of the exciting light beam. This phenomenon was applied to detect ultrasmall deflections of silicon dioxide cantilevers of submicrometer thickness that were fabricated with corrugation on top to act as diffraction grating couplers. The power of light coupled into the cantilevers was monitored with a conventional photodetector and modulated using mechanical vibration of the cantilever, thus changing the spatial orientation of the coupler with respect to the incident light beam. The technique can be considered as an alternative to the methods known for detection of cantilever deflection.

  3. Link between diffraction losses and light beam cross section in laser with telescopic resonator

    SciTech Connect

    Dmitriev, A.K.; Nekrasov, Yu.V.

    1987-06-01

    The light beam cross section change in a laser and its link with the diffraction losses during the telescopic converter defocusing is discussed. In addition, the measurements of the resonator astigmatism compensation by the Brewster window are carried out. It is demonstrated that in the resonator stability region, the light beam cross section is well described by the expression using the transmission matrix elements, the simplified model for the diffraction qualitatively correlates with the test data, and the mirror astigmatism due to the inclined light beam incidence is compensated for by Brewster's window.

  4. Small modulation ellipsometry

    NASA Technical Reports Server (NTRS)

    Ducharme, Stephen P. (Inventor); El Hajj, Hassanayn M. (Inventor); Johs, Blaine D. (Inventor); Woollam, John A. (Inventor)

    1995-01-01

    In an ellipsometer, a phase-modulated, polarized light beam is applied to a sample, electrical signals are obtained representing the orthogonal planes of polarization of the light after it has interacted with the sample and the constants of the sample are calculated from the two resulting electrical signals. The phase modulation is sufficiently small so that the calibration errors are negligible. For this purpose, the phase modulator phase modulates the light within a range of no more than ten degrees modulations peak to peak. The two electrical signals are expanded by Fourier analysis and the coefficients thereof utilized to calculate psi and delta.

  5. Measurement of sarcomere shortening in skinned fibers from frog muscle by white light diffraction.

    PubMed Central

    Goldman, Y E

    1987-01-01

    A new optical-electronic method has been developed to detect striation spacing of single muscle fibers. The technique avoids Bragg-angle and interference-fringe effects associated with laser light diffraction by using polychromatic (white) light. The light is diffracted once by an acousto-optical device and then diffracted again by the muscle fiber. The double diffraction reverses the chromatic dispersion normally obtained with polychromatic light. In frog skinned muscle fibers, active and passive sarcomere shortening were smooth when observed by white light diffraction, whereas steps and pauses occurred in the striation spacing signals obtained with laser illumination. During active contractions skinned fibers shortened at high rates (3-5 microns/s per half sarcomere, 0-5 degrees C) at loads below 5% of isometric tension. Compression of the myofibrillar lateral filament spacing using osmotic agents reduced the shortening velocity at low loads. A hypothesis is presented that high shortening velocities are observed with skinned muscle fibers because the cross-bridges cannot support compressive loads when the filament lattice is swollen. Images FIGURE 2 PMID:3496924

  6. Complex-valued acquisition of the diffraction imaging by incoherent quasimonochromatic light without a support constraint

    SciTech Connect

    Zhang Minghui; Xu Jianfei; Wang Xianfu; Wei Qing

    2010-10-15

    A scheme for complex-valued acquisition of the diffraction imaging with quasimonochromatic incoherent light is theoretically proposed. The main idea is to project the real and the imaginary parts of a Fraunhofer diffraction field on intensity distributions, respectively, with the use of a {pi}/2 phase-changing plate. The whole procedure is iterative algorithm free and needs no a priori knowledge of an arbitrary object. A numerical experiment and a quantitative confirmation are also given. To our knowledge, it was the first physical proposal for the complex-valued acquisition of a diffraction imaging by two-dimensional coherent patterns with thermal illumination.

  7. General algorithm to optimize the diffraction efficiency of a phase-type spatial light modulator.

    PubMed

    Cibula, Matthew A; McIntyre, David H

    2013-08-01

    We present a general approach for optimizing the diffraction efficiency of a phase-type spatial light modulator (SLM). While the SLM displays a one-dimensional phase grating, the phase shift of one pixel in the grating is varied and the first-order diffraction efficiency is measured. This is repeated pixel-by-pixel to find the optimum phase encoding for the device that maximizes the diffraction efficiency. This method compensates for nonlinearity of the modulator phase response and is especially useful for optimizing modulators with less than 2π phase shift.

  8. Effect of spectral correlations on spectral switches in the diffraction of partially coherent light.

    PubMed

    Pu, Jixiong; Nemoto, Shojiro; Lü, Baida

    2003-10-01

    The subject is the spectral characteristics of partially coherent light whose spectral degree of coherence satisfies or violates the scaling law in diffraction by a circular aperture. Three kinds of spectral correlations of the incident light are considered. It is shown that no matter whether the partially coherent light satisfies or violates the scaling law, a spectral switch defined as a rapid transition of spectral shifts is always found in the diffraction field. Different spectral correlations of the incident field in the aperture result in different points at which the spectral switch occurs. With an increment in the correlations, the position at which the spectral switch takes place moves toward the point at which the phase of the center frequency component omega0 becomes singular for illumination by spatially fully coherent light. For light that satisfies the scaling law, the spectral switch is attributed to the diffraction-induced spectral changes; for partially coherent light that violates the scaling law, the spectral switch is attributed to both the diffraction-induced spectral changes and the correlation-induced spectral changes.

  9. Calculating the Fresnel diffraction of light from a shifted and tilted plane.

    PubMed

    Yamamoto, Kenji; Ichihashi, Yasuyuki; Senoh, Takanori; Oi, Ryutaro; Kurita, Taiichiro

    2012-06-04

    We propose a technique for calculating the diffraction of light in the Fresnel region from a plane that is the light source (source plane) to a plane at which the diffracted light is to be calculated (destination plane). When the wavefield of the source plane is described by a group of points on a grid, this technique can be used to calculate the wavefield of the group of points on a grid on the destination plane. The positions of both planes may be shifted, and the plane normal vectors of both planes may have different directions. Since a scaled Fourier transform is used for the calculation, it can be calculated faster than calculating the diffraction by a Fresnel transform at each point. This technique can be used to calculate and generate planar holograms from computer graphics data.

  10. Investigation of correlation properties of light fields by Fresnel diffraction from a step

    NASA Astrophysics Data System (ADS)

    Hosseini, S. R.; Tavassoly, M. T.

    2013-12-01

    We introduce a new method, based on Fresnel diffraction of light from a step, for the study of correlation properties (temporal and spatial) of optical fields. The method renders to measure wavelength, coherence length, and coherence width by recording the visibility of the diffraction fringes versus optical path difference and spacing of the interfering beams. In addition, the method permits to specify the spectral line shape, particularly, of lights with short coherence lengths and the spatial coherence behavior of the lights with short coherence widths. Since, in the introduced method the optical path difference can be varied by changing the light incident angle, practically, in an interval of 90º, a large volume of data is acquired which leads to reliable and accurate study of the subject. The method can be applied easily using modest equipment. We have applied the method to the study of correlation properties of the lights emitted by LED, incandescent bulb, and Hg lamp.

  11. Highly Effective Light Beam Diffraction on Holographic PDLC Photonic Structure, Controllable by the Spatially Inhomogeneous Electric Field

    NASA Astrophysics Data System (ADS)

    Semkin, A. O.; Sharangovich, S. N.

    In this work the highly effiective light beam diffraction on holographic photonic structure formed in polymer-dispersed liquid crystal (PDLCs) is theoretically described. The ability to manage its diffraction characteristics by the spatially inhomogeneous electric field is also shown.

  12. Diffraction-free light droplets for axially-resolved volume imaging.

    PubMed

    Antonacci, G; Domenico, G Di; Silvestri, S; DelRe, E; Ruocco, G

    2017-12-01

    An ideal direct imaging system entails a method to illuminate on command a single diffraction-limited region in a generally thick and turbid volume. The best approximation to this is the use of large-aperture lenses that focus light into a spot. This strategy fails for regions that are embedded deep into the sample, where diffraction and scattering prevail. Airy beams and Bessel beams are solutions of the Helmholtz Equation that are both non-diffracting and self-healing, features that make them naturally able to outdo the effects of distance into the volume but intrinsically do not allow resolution along the propagation axis. Here, we demonstrate diffraction-free self-healing three-dimensional monochromatic light spots able to penetrate deep into the volume of a sample, resist against deflection in turbid environments, and offer axial resolution comparable to that of Gaussian beams. The fields, formed from coherent mixtures of Bessel beams, manifest a more than ten-fold increase in their undistorted penetration, even in turbid milk solutions, compared to diffraction-limited beams. In a fluorescence imaging scheme, we find a ten-fold increase in image contrast compared to diffraction-limited illuminations, and a constant axial resolution even after four Rayleigh lengths. Results pave the way to new opportunities in three-dimensional microscopy.

  13. Light Diffraction of Aligned Polymer Fibers Periodically Dispersed by Phase Separation of Liquid Crystal and Polymer

    NASA Astrophysics Data System (ADS)

    Murashige, Takeshi; Fujikake, Hideo; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro; Sato, Fumio

    2004-12-01

    We have confirmed light diffraction of aligned polymer fibers obtained by a phase separation of an anisotropic-phase solution of liquid crystal and polymer. He—Ne laser light passing through the polymer fibers was scattered in the axis vertical to the fibers, and had two peaks of light intensity symmetrical to the center of the transmitting laser spot. The two peaks were found to be caused by light diffraction due to the periodic polymer-fiber dispersion because the peaks corresponded to values calculated by intervals between the fibers. The periodical fiber networks are considered to be formed by anisotropic spinodal decomposition. This effect can be used to measure the dispersion order of the polymer fibers.

  14. Evidence for inhibited diffraction of light propagating through nanolaminate metallodielectric material.

    PubMed

    Roberts, M J; Guenthner, Andrew; Feng, Simin

    2007-09-17

    We report the fabrication and characterization of laterally continuous silver layers alternated with glassy amorphous polycarbonate films with the thickness of each layer much less than the wavelength. Such films exhibit physical phenomena associated with the coupled plasmon resonances. We have characterized light propagation through the resulting metal-dielectric (MD) periodic structures using collection mode Near Field Scanning Optical Microscopy (NSOM). In agreement with published theoretical models, our experiments provide evidence that diffraction can be inhibited for light propagating through metallodielectric nanolaminate.

  15. Novel cases of diffraction of light from a grating: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Jetty, Ninad R.; Suman, Akash; Khaparde, Rajesh B.

    2012-11-01

    A popular pedagogical approach for introducing diffraction is to assume normal incidence of light on a single slit or a plane transmission grating. Interesting cases of diffraction from a grating at orientations other than normal incidence remain largely unexplored. In this article, we report our study of these unexplored cases, which was taken up as an undergraduate student project. We define various cases of orientation of the grating and use the Fresnel-Kirchhoff formula to arrive at the diffracted intensity distribution. An experimental arrangement consisting of a laser, a grating mount, a digital camera, and a calibrated plane screen is employed to record our observations. We discuss for each case the theoretical and experimental results and establish the conformity between the two. Finally, we analyze the details of various cases and conclude that for an arbitrary orientation of the grating, the diffraction maxima fall along a second degree curve.

  16. Breaking the diffraction limit of light-sheet fluorescence microscopy by RESOLFT

    NASA Astrophysics Data System (ADS)

    Hoyer, Patrick; de Medeiros, Gustavo; Balázs, Bálint; Norlin, Nils; Besir, Christina; Hanne, Janina; Kräusslich, Hans-Georg; Engelhardt, Johann; Sahl, Steffen J.; Hell, Stefan W.; Hufnagel, Lars

    2016-03-01

    We present a plane-scanning RESOLFT [reversible saturable/switchable optical (fluorescence) transitions] light-sheet (LS) nanoscope, which fundamentally overcomes the diffraction barrier in the axial direction via confinement of the fluorescent molecular state to a sheet of subdiffraction thickness around the focal plane. To this end, reversibly switchable fluorophores located right above and below the focal plane are transferred to a nonfluorescent state at each scanning step. LS-RESOLFT nanoscopy offers wide-field 3D imaging of living biological specimens with low light dose and axial resolution far beyond the diffraction barrier. We demonstrate optical sections that are thinner by 5-12-fold compared with their conventional diffraction-limited LS analogs.

  17. Spin-orbit interaction of light and diffraction of polarized beams

    NASA Astrophysics Data System (ADS)

    Bekshaev, Aleksandr Ya

    2017-08-01

    The edge diffraction of a homogeneously polarized light beam is studied theoretically based on the paraxial optics and Fresnel-Kirchhoff approximation, and the dependence of the diffracted beam pattern of the incident beam polarization is predicted. If the incident beam is circularly polarized, the trajectory of the diffracted beam center of gravity exhibits a small angular deviation from the geometrically expected direction. The deviation is parallel to the screen edge and reverses the sign with the polarization handedness; it is explicitly calculated for the case of a Gaussian incident beam with a plane wavefront. This effect is a manifestation of the spin-orbit interaction of light and can be interpreted as a revelation of the internal spin energy flow immanent in circularly polarized beams. It also exposes the vortex character of the weak longitudinal field component associated with the circularly polarized incident beam.

  18. Polarization sensitivity of light diffraction for periodic array of anisotropic gold nanoparticles

    SciTech Connect

    Tsai, Ming-shan Liu, Tung-kai; Tsen, Chun-yu; Ting, Chen-ching

    2015-06-15

    This article aims to analyze the first order diffraction intensity of the incident polarized light which is diffracted by the gold nanoparticles array in terms of the surface plasmon effect. The inspected gold nanoparticles array films are built in grating pattern with stripe thickness of 4 μm and diameters of gold nanoparticles ca. 10–56 nm, which are formed by annealing at temperatures of 400, 450, 500, and 550 °C, respectively. The probing light is linearly polarized with wavelengths of 450–800 nm and counterclockwise turns its polarization direction from 0° to 90° during measurements. The results show that the diffraction intensity depends on the anisotropic configuration samples which gold nanoparticles are orientated by analyzing the scanning electron microscope images. It results that the localized surface plasmon effect induced by incident field depends on orientation and causes the sample polarization-sensitive.

  19. Adaptive Fraunhofer diffraction particle sizing instrument using a spatial light modulator.

    PubMed

    Hirleman, E D; Dellenback, P A

    1989-11-15

    Integration of a magnetooptic spatial light modulator into a Fraunhofer diffraction particle sizing instrument is proposed and demonstrated theoretically and experimentally. The concept gives the instrument the ability to reconfigure a detector array on-line and thereby adapt to the measurement context.

  20. Geometrical Reasoning in Wave Situations: The Case of Light Diffraction and Coherent Illumination Optical Imaging

    ERIC Educational Resources Information Center

    Maurines, Laurence

    2010-01-01

    This particular study is part of a research programme on the difficulties encountered by students when learning about wave phenomena in a three-dimensional medium in the absence or presence of obstacles. It focuses on how students reason in situations in which wave optics need to be used: diffraction of light by an aperture, imaging in the…

  1. Geometrical Reasoning in Wave Situations: The Case of Light Diffraction and Coherent Illumination Optical Imaging

    ERIC Educational Resources Information Center

    Maurines, Laurence

    2010-01-01

    This particular study is part of a research programme on the difficulties encountered by students when learning about wave phenomena in a three-dimensional medium in the absence or presence of obstacles. It focuses on how students reason in situations in which wave optics need to be used: diffraction of light by an aperture, imaging in the…

  2. Automatic null ellipsometry with an interferometer

    SciTech Connect

    Watkins, Lionel R.

    2009-11-10

    A new approach to automatic null ellipsometry is described in which the analyzer of a traditional polarizer compensator sample analyzer (PCSA) null ellipsometer is replaced with a heterodyne Michelson interferometer. One arm of this interferometer is modified such that it produces a fixed, linearly polarized reference beam, irrespective of the input polarization state. This beam is recombined interferometrically with the measurement beam and spatially separated into its p and s polarizations. The relative phase of the resulting temporal fringes is a linear function of the polarizer azimuthal angle P, and thus this component can be driven to its null position without iteration. Once at null, the azimuthal angle of the reflected, linearly polarized light is trivially determined from the relative amplitude of the fringes. Measurements made with this instrument on a native oxide film on a silicon wafer were in excellent agreement with those made with a traditional PCSA null ellipsometer.

  3. Teaching Diffraction of Light and Electrons: Classroom Analogies to Classic Experiments

    NASA Astrophysics Data System (ADS)

    Velentzas, Athanasios

    2014-11-01

    Diffraction and interference are phenomena that demonstrate the wave nature of light and of particles. Experiments relating to the diffraction/interference of light can easily be carried out in an educational lab, but it may be impossible to perform experiments involving electrons because of the lack of specialized equipment needed for such experiments. It would, however, be possible for students to analyze data from scientific experiments by analogy to experiments they themselves had performed. Based on this rationale, this paper describes two pairs of experiments that may be of interest to teachers aiming to teach the wave nature of light and of particles to upper secondary school (or to college) students. Specifically, students are asked to (i) carry out a double-slit experiment by using monochromatic light, thus repeating in a way the historical experiment of Young,1 and then analyze real data from Jönsson's2-3 scientific double-slit experiment with electrons, and (ii) perform an experiment involving diffraction of monochromatic light using a compact disc (CD) as a reflection grating, and then by analogy analyze data from the experiment of Davisson and Germer.4 The proposed real experiments are not original, and different versions of them have been wi dely described in the literature.5,6 The educational value of the present work lies in the use of the analogy between experiments carried out in the school lab and experiments performed in the scientific lab.

  4. Uniformity of reshaped beam by diffractive optical elements with light-emitted diode illumination

    NASA Astrophysics Data System (ADS)

    Chen, Mengzhu; Gu, Huarong; Wang, Qixia; Tan, Qiaofeng

    2015-10-01

    Due to its low energy consumption, high efficiency and fast switching speed, light-emitted diode (LED) has been used as a new light source in optical wireless communication. To ensure uniform lighting and signal-to-noise ratio (SNR) during the data transmission, diffractive optical elements (DOEs) can be employed as optical antennas. Different from laser, LED has a low temporal and spatial coherence. And its impacts upon the far-field diffraction patterns of DOEs remain unclear. Thus the mathematical models of far-field diffraction intensity for LED with a spectral bandwidth and source size are first derived in this paper. Then the relation between source size and uniformity of top-hat beam profile for LEDs either considering the spectral bandwidth or not are simulated. The results indicate that when the size of LED is much smaller than that of reshaped beam, the uniformity of reshaped beam obtained by light source with a spectral bandwidth is significantly better than that by a monochromatic light. However, once the size is larger than a certain threshold value, the uniformity of reshaped beam of two LED models are almost the same, and the influence introduced by spectral bandwidth can be ignored. Finally the reshaped beam profiles are measured by CCD camera when the areas of LED are 0.5×0.5mm2 and 1×1mm2. And the experimental results agree with the simulations.

  5. Light trapping by backside diffraction gratings in silicon solar cells revisited.

    PubMed

    Wellenzohn, Markus; Hainberger, Rainer

    2012-01-02

    This numerical study investigates the influence of rectangular backside diffraction gratings on the efficiency of silicon solar cells. Backside gratings are used to diffract incident light to large propagation angles beyond the angle of total internal reflection, which can significantly increase the interaction length of long wavelength photons inside the silicon layer and thus enhance the efficiency. We investigate the influence of the silicon thickness on the optimum grating period and modulation depth by a simulation method which combines a 2D ray tracing algorithm with rigorous coupled wave analysis (RCWA) for calculating the grating diffraction efficiencies. The optimization was performed for gratings with period lengths ranging from 0.25 µm to 1.5 µm and modulation depths ranging from 25 nm to 400 nm under the assumption of normal light incidence. This study shows that the achievable efficiency improvement of silicon solar cells by means of backside diffraction gratings strongly depends on the proper choice of the grating parameters for a given silicon thickness. The relationship between the optimized grating parameters resulting in maximum photocurrent densities and the silicon thickness is determined. Moreover, the thicknesses of silicon solar cells with and without optimized backside diffraction gratings providing the same photocurrent densities are compared.

  6. A fast multispectral light synthesiser based on LEDs and a diffraction grating

    PubMed Central

    Belušič, Gregor; Ilić, Marko; Meglič, Andrej; Pirih, Primož

    2016-01-01

    Optical experiments often require fast-switching light sources with adjustable bandwidths and intensities. We constructed a wavelength combiner based on a reflective planar diffraction grating and light emitting diodes with emission peaks from 350 to 630 nm that were positioned at the angles corresponding to the first diffraction order of the reversed beam. The combined output beam was launched into a fibre. The spacing between 22 equally wide spectral bands was about 15 nm. The time resolution of the pulse-width modulation drivers was 1 ms. The source was validated with a fast intracellular measurement of the spectral sensitivity of blowfly photoreceptors. In hyperspectral imaging of Xenopus skin circulation, the wavelength resolution was adequate to resolve haemoglobin absorption spectra. The device contains no moving parts, has low stray light and is intrinsically capable of multi-band output. Possible applications include visual physiology, biomedical optics, microscopy and spectroscopy. PMID:27558155

  7. A fast multispectral light synthesiser based on LEDs and a diffraction grating

    NASA Astrophysics Data System (ADS)

    Belušič, Gregor; Ilić, Marko; Meglič, Andrej; Pirih, Primož

    2016-08-01

    Optical experiments often require fast-switching light sources with adjustable bandwidths and intensities. We constructed a wavelength combiner based on a reflective planar diffraction grating and light emitting diodes with emission peaks from 350 to 630 nm that were positioned at the angles corresponding to the first diffraction order of the reversed beam. The combined output beam was launched into a fibre. The spacing between 22 equally wide spectral bands was about 15 nm. The time resolution of the pulse-width modulation drivers was 1 ms. The source was validated with a fast intracellular measurement of the spectral sensitivity of blowfly photoreceptors. In hyperspectral imaging of Xenopus skin circulation, the wavelength resolution was adequate to resolve haemoglobin absorption spectra. The device contains no moving parts, has low stray light and is intrinsically capable of multi-band output. Possible applications include visual physiology, biomedical optics, microscopy and spectroscopy.

  8. LIGHT MODULATION: Wide-aperture diffraction of unpolarised radiation in a system of two acousto-optic filters

    NASA Astrophysics Data System (ADS)

    Magdich, L. N.; Yushkov, K. B.; Voloshinov, V. B.

    2009-04-01

    Light diffraction is studied in two tandem acousto-optic cells filtering unpolarised radiation with a wide angular spectrum. It is shown that the side lobes of the ultrasonic radiation pattern of a piezoelectric transducer produce side diffraction intensity maxima at the output of the system consisting of two filters. Diffraction in paratellurite filters is studied experimentally at 1.06 μm.

  9. Bragg diffraction for normal and obliquely circularly polarized light due a new chiral mixture

    NASA Astrophysics Data System (ADS)

    Castro-Garay, P.; Manzanares-Martinez, J.; Corella-Madueño, A.; Rosas-Burgos, A.; Lizola, Josue; Clark, Marielena; Palma, Lillian

    2015-09-01

    We have found experimentally the transmittance of normal incident circularly polarized light due to new chiral mixture that was distorted by electric field. The chiral mixture was achieved by mixtures of two nematic liquid crystals (5OCB and 5CB) and S-1-bromo-2-methylbutane. We have found a regime of circular Bragg diffraction for certain values of concentrations and thickness. Optical diffraction phenomenon have received particular attention in research for optical and electro-optical applications, such as low -voltage modulators, reflective phase gratings and smart reflectors.

  10. Nonreciprocal diffraction of light based on double-transition-assisted photonic Aharonov-Bohm effect

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Li, Yanfeng

    2016-10-01

    We propose a nonreciprocal diffraction system based on the photonic Aharonov-Bohm effect. The implementation utilizes the simultaneous up and down photonic transition of Bloch modes in a dielectric grating created by time-harmonic dielectric constant modulation. This double transition process generates opposite effective magnetic fluxes for photons in symmetric and antisymmetric modes, which gives rise to nonreciprocal spatial interference between them. With the broken time-reversal symmetry, this system is possible to exhibit unidirectional highly efficient diffraction, which enables grating-based nonmagnetic isolation and circulation of free space light, and integrates the functions of gratings and isolators.

  11. Analysis of beam steering by diffraction and the scattering of light by turbulence

    NASA Astrophysics Data System (ADS)

    Tsui, Jing M.

    This thesis addresses two problems. The first is the performance of non-mechanical beam steering devices based on diffractive optics, and the second is the problem of the scattering of light by turbulence. Two beam steering devices namely holographic optical elements and optical phased arrays are analyzed. Of particular interest are the wavelength selectivity of the uniform volume holographic grating and the impact of dispersion on the spatial and temporal fidelity of an optically transmitted communication signal through both beamsteering devices. Longitudinal refractive index modulation (apodization) in photosensitive glass is used to improve sidelobe. Theoretical methods are developed to model both devices. For uniform grating, it is shown that the temporal dispersion due to the diffraction increase with beam diameter yielding a higher power penalty for large diffraction angles and aperture sizes. For an optical phased array, it is shown the power penalty increase as the diffraction angles and diameters increase. In addition, the scattering of light in turbulent medium is investigated. Of particular interest is to determine region of validity of the Born approximation which is used to compute the scattering field. Pade approximants are used to analyze the propagation through a media having strong turbulent intensity. It is shown that the region of convergence of Born approximation increases as the outer scale of the turbulence decreases. In the case of the strong turbulence, the Born approximation does not capture the correct angular distribution of the scattering intensity.

  12. Development of biosensor based on imaging ellipsometry and its applications

    NASA Astrophysics Data System (ADS)

    Jin, Gang

    2011-03-01

    We have reviewed the development of the biosensor based on imaging ellipsometry including its principle, methodology and general engineering model structure, mainly compared experimental setups between the previous one and the recently developed one. It's obvious that the sensitivity and the signal to noise ratio has been improved by a various spectroscopic light source, the optimization of polarized components setting and a cool CCD, especially the contribution of the CCD, which makes the biosensor available in more and more biomedical applications.

  13. Immobilization of biomolecules onto surfaces according to ultraviolet light diffraction patterns

    SciTech Connect

    Bjoern Petersen, Steffen; Kold di Gennaro, Ane; Neves-Petersen, Maria Teresa; Skovsen, Esben; Parracino, Antonietta

    2010-10-01

    We developed a method for immobilization of biomolecules onto thiol functionalized surfaces according to UV diffraction patterns. UV light-assisted molecular immobilization proceeds through the formation of free, reactive thiol groups that can bind covalently to thiol reactive surfaces. We demonstrate that, by shaping the pattern of the UV light used to induce molecular immobilization, one can control the pattern of immobilized molecules onto the surface. Using a single-aperture spatial mask, combined with the Fourier transforming property of a focusing lens, we show that submicrometer (0.7 {mu}m) resolved patterns of immobilized prostate-specific antigen biomolecules can be created. If a dual-aperture spatial mask is used, the results differ from the expected Fourier transform pattern of the mask. It appears as a superposition of two diffraction patterns produced by the two apertures, with a fine structured interference pattern superimposed.

  14. Diffraction of Laser Light as a Probe of Ordered Tissue Structure

    NASA Astrophysics Data System (ADS)

    Stewart, Cody; Forrester, Kevin; Frank, C. B.; Irvine-Halliday, David; Muldrew, Ken; Shrive, Nigel; Thompson, Robert

    2002-05-01

    Laser light transmitted through thin slices of ordered tissue, such as tendon and ligament, forms a diffraction pattern elongated in the direction perpendicular to the alignment direction of the tissue fibers. The degree of elongation provides information on the degree of order in the tissue sample and thus provides a probe of the presence of scar tissue since, when damaged, collagen fibers reform more randomly than in healthy tissue. Small Angle Light Scattering (SALS) is an established technique that utilizes the diffraction properties of ordered tissue to determine bulk properties such as angle and degree of fiber orientation. This presentation will present experimental data that appears to dispute certain basic assumptions inherent in the method, as well as a basic theoretical explanation for why these assumptions may be inadequate under some experimental conditions.

  15. Predictions for diffractive ɸ meson production using an AdS/QCD light-front wavefunction

    NASA Astrophysics Data System (ADS)

    Ahmady, Mohammad; Sandapen, Ruben; Sharma, Neetika

    2017-03-01

    We compute the rate for diffractive ɸ electro-production using the Color Glass Condensate dipole model. The model parameters are obtained from fits to the most recent combined HERA data on inclusive deep inelastic scattering. As for the ɸ meson, we use an AdS/QCD holographic light front wavefunction. Our predictions are compared to the available data collected at the HERA collider.

  16. Diffraction Free Light Source for Ghost Imaging of Objects Viewed Through Obscuring Media

    DTIC Science & Technology

    2010-02-01

    Ghost Imaging ( QGI ) to exploit quantum optical information. This research experimentally demonstrated the ability of diffraction free light sources to...the capability of QGI to reveal images of objects through partial obstructions of the illumination. The results of this effort also demonstrated the... QGI ) to exploit quantum optical information. QGI increases versatility in imaging objects of interest to the warfighter. The Army fights in all

  17. Evaluation of photoelectric processes in photorefractive crystals via the exposure characteristics of light diffraction.

    PubMed

    Kadys, A; Gudelis, V; Sudzius, M; Jarasiunas, K

    2005-01-12

    We demonstrate a novel way to analyse carrier recombination and transport processes in photorefractive semiconductors via the exposure characteristics of light induced diffraction. The results of a picosecond four-wave mixing on free carrier gratings in semi-insulating GaAs crystals at various grating periods and modulation depths of a light interference pattern are discussed. The role of a deep-trap recharging in carrier diffusion and recombination is sensitively revealed through a feedback effect of a space-charge field to non-equilibrium carrier transport.

  18. Fraunhofer diffraction of light with orbital angular momentum by a slit.

    PubMed

    Ferreira, Queila S; Jesus-Silva, Alcenísio J; Fonseca, Eduardo J S; Hickmann, Jandir M

    2011-08-15

    We study the Fraunhofer diffraction problem while taking into account the orbital angular momentum of light. In this case, the phase singularity of the light beam is incident on the slit in two different cases: in one, it is incident slightly above the slit, and in the other it is centered on the slit. We observed that the symmetry and the fringe formation in the interference pattern strongly depend on the amount of orbital angular momentum and the slit position in relation to the beam.

  19. Diffraction as a reason for slowing down light pulses in vacuum

    NASA Astrophysics Data System (ADS)

    Fedorov, M. V.; Vintskevich, S. V.; Grigoriev, D. A.

    2017-03-01

    The mean velocity of a finite-size short light pulse in a far zone is defined as the vectorial sum of velocities of all rays forming the pulse. Because of diffraction, the mean pulse velocity defined in this way is always somewhat smaller than the speed of light. The conditions are found when this slowing-down effect is sufficiently pronounced to be experimentally measurable. Under these conditions the original Gaussian shape of a pulse is found to be strongly modified with significant lengthening of the rear wing of the field envelope. Schemes for measuring these effects are suggested and discussed.

  20. Peculiarities of propagation of quasi-diffraction-free light beams in strongly scattering absorbing media

    SciTech Connect

    Katsev, I L; Prikhach, A S; Kazak, N S; Kroening, M

    2006-04-30

    Based on the relation between the theory of light field coherence and theory of radiation transfer in scattering media, a method is proposed for calculating the illumination distribution produced by coherent quasi-diffraction-free beams at different penetration depths of radiation into scattering media such as biological tissues. The method uses the optical transfer function or the point spread function (PSF) of the medium. A simple and convenient analytic PSF model is described. Examples of the illumination distribution produced by a Bessel light beam in a medium with optical parameters typical of real biological tissues are presented. It is shown that the half-width of the axial maximum of a Bessel light beam scattered due to scattering almost does not increase up to optical depths where the contribution of multiple scattering is already considerable. (light beams)

  1. Diffractive intermediate layer enables broadband light trapping for high efficiency ultrathin c-Si tandem cells

    NASA Astrophysics Data System (ADS)

    Li, Guijun; Ho, Jacob Y. L.; Li, He; Kwok, Hoi-Sing

    2014-06-01

    Light management through the intermediate reflector in the tandem cell configuration is of great practical importance for achieving high stable efficiency and also low cost production. So far, however, the intermediate reflectors employed currently are mainly focused on the light absorption enhancement of the top cell. Here, we present a diffractive intermediate layer that allows for light trapping over a broadband wavelength for the ultrathin c-Si tandem solar cell. Compared with the standard intermediate reflector, this nanoscale architectural intermediate layer results in a 35% and 21% remarkable enhancement of the light absorption in the top (400-800 nm) and bottom (800-1100 nm) cells simultaneously, and ultrathin c-Si tandem cells with impressive conversion efficiency of 13.3% are made on the glass substrate.

  2. Spatial and spectral image distortions caused by diffraction of an ordinary polarised light beam by an ultrasonic wave

    SciTech Connect

    Machikhin, A S; Pozhar, V E

    2015-02-28

    We consider the problem of determining the spatial and spectral image distortions arising from anisotropic diffraction by ultrasonic waves in crystals with ordinary polarised light (o → e). By neglecting the small-birefringence approximation, we obtain analytical solutions that describe the dependence of the diffraction angles and wave mismatch on the acousto-optic (AO) interaction geometry and crystal parameters. The formulas derived allow one to calculate and analyse the magnitude of diffraction-induced spatial and spectral image distortions and to identify the main types of distortions: chromatic compression and trapezoidal deformation. A comparison of the values of these distortions in the diffraction of ordinary and extraordinary polarised light shows that they are almost equal in magnitude and opposite in signs, so that consistent diffraction (o → e → o or e → o → e) in two identical AO cells rotated through 180° in the plane of diffraction can compensate for these distortions. (diffraction of radiation)

  3. Characterization of semicrystalline polymers after nanoimprint by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Wang, Si; Rond, Johannes; Steinberg, Christian; Papenheim, Marc; Scheer, Hella-Christin

    2016-02-01

    Semicrystalline Reg-P3HT (regio-regular poly-3-hexylthiophene) is a promising material for organic electronics. It features relatively high charge mobility and enables easy preparation because of its solubility. Due to its high optical and electrical anisotropy, the size, number and orientation of the ordered domains are important for applications. To control these properties without limitation from crystalline domains existing after spin coating, thermal nanoimprint is performed beyond the melting point. The state of the art of measurement to analyze the complex morphology is X-ray diffraction (XRD). We address an alternative measurement method to characterize the material by its optical properties, spectroscopic ellipsometry. It provides information on the degree of order from the typical fingerprint absorption spectrum. In addition, when the material is modeled as a uniaxial layer, an anisotropy factor can be derived. The results obtained from spectroscopic ellipsometry are in accordance with those from XRD. In particular, spectroscopic ellipsometry is able to distinguish between order along the backbone and order in π- π stacking direction, which is important with respect to conductivity.

  4. LIGHT BEAMS: Peculiarities of propagation of quasi-diffraction-free light beams in strongly scattering absorbing media

    NASA Astrophysics Data System (ADS)

    Katsev, I. L.; Prikhach, A. S.; Kazak, N. S.; Kroening, M.

    2006-04-01

    Based on the relation between the theory of light field coherence and theory of radiation transfer in scattering media, a method is proposed for calculating the illumination distribution produced by coherent quasi-diffraction-free beams at different penetration depths of radiation into scattering media such as biological tissues. The method uses the optical transfer function or the point spread function (PSF) of the medium. A simple and convenient analytic PSF model is described. Examples of the illumination distribution produced by a Bessel light beam in a medium with optical parameters typical of real biological tissues are presented. It is shown that the half-width of the axial maximum of a Bessel light beam scattered due to scattering almost does not increase up to optical depths where the contribution of multiple scattering is already considerable.

  5. Efficiency and stray light measurements and calculations of diffraction gratings for the Advanced Light Source

    SciTech Connect

    McKinney, W.R.; Mossessian, D. ); Gullikson, E. ); Heimann, P. )

    1995-02-01

    Water-cooled gratings manufactured for spherical grating monochromators of the Advanced Light Source beamlines 7.0, 8.0, and 9.0 were measured with the laser plasma source and reflectometer in the Center for X-ray Optics at Lawrence Berkeley Laboratory. The square-wave gratings are ion milled into the polished electroless nickel surface after patterning by holographic photolithography. Absolute efficiency data are compared with exact electromagnetic theory calculation. Interorder stray light and groove depths can be estimated from the measurements.

  6. Linear discrete diffraction and transverse localization of light in two-dimensional backbone lattices.

    PubMed

    Qi, Yiling; Zhang, Guoquan

    2010-09-13

    We study the linear discrete diffraction characteristics of light in two-dimensional backbone lattices. It is found that, as the refractive index modulation depth of the backbone lattice increases, high-order band gaps become open and broad in sequence, and the allowed band curves of the Floquet-Bloch modes become flat gradually. As a result, the diffraction pattern at the exit face converges gradually for both the on-site and off-site excitation cases. Particularly, when the refractive index modulation depth of the backbone lattice is high enough, for example, on the order of 0.01 for a square lattice, the light wave propagating in the backbone lattice will be localized in transverse dimension for both the on-site and off-site excitation cases. This is because only the first several allowed bands with nearly flat band curves are excited in the lattice, and the transverse expansion velocities of the Floquet-Bloch modes in these flat allowed bands approach to zero. Such a linear transverse localization of light may have potential applications in navigating light propagation dynamics and optical signal processing.

  7. The MYTHEN detector for X-ray powder diffraction experiments at the Swiss Light Source

    PubMed Central

    Bergamaschi, Anna; Cervellino, Antonio; Dinapoli, Roberto; Gozzo, Fabia; Henrich, Beat; Johnson, Ian; Kraft, Philipp; Mozzanica, Aldo; Schmitt, Bernd; Shi, Xintian

    2010-01-01

    The MYTHEN single-photon-counting silicon microstrip detector has been developed at the Swiss Light Source for time-resolved powder diffraction experiments. An upgraded version of the detector has been installed at the SLS powder diffraction station allowing the acquisition of diffraction patterns over 120° in 2θ in fractions of seconds. Thanks to the outstanding performance of the detector and to the calibration procedures developed, the quality of the data obtained is now comparable with that of traditional high-resolution point detectors in terms of FWHM resolution and peak profile shape, with the additional advantage of fast and simultaneous acquisition of the full diffraction pattern. MYTHEN is therefore optimal for time-resolved or dose-critical measurements. The characteristics of the MYTHEN detector together with the calibration procedures implemented for the optimization of the data are described in detail. The refinements of two known standard powders are discussed together with a remarkable application of MYTHEN to organic compounds in relation to the problem of radiation damage. PMID:20724787

  8. Laser light routing in an elongated micromachined vapor cell with diffraction gratings for atomic clock applications

    PubMed Central

    Chutani, Ravinder; Maurice, Vincent; Passilly, Nicolas; Gorecki, Christophe; Boudot, Rodolphe; Abdel Hafiz, Moustafa; Abbé, Philippe; Galliou, Serge; Rauch, Jean-Yves; de Clercq, Emeric

    2015-01-01

    This paper reports on an original architecture of microfabricated alkali vapor cell designed for miniature atomic clocks. The cell combines diffraction gratings with anisotropically etched single-crystalline silicon sidewalls to route a normally-incident beam in a cavity oriented along the substrate plane. Gratings have been specifically designed to diffract circularly polarized light in the first order, the latter having an angle of diffraction matching the (111) sidewalls orientation. Then, the length of the cavity where light interacts with alkali atoms can be extended. We demonstrate that a longer cell allows to reduce the beam diameter, while preserving the clock performances. As the cavity depth and the beam diameter are reduced, collimation can be performed in a tighter space. This solution relaxes the constraints on the device packaging and is suitable for wafer-level assembly. Several cells have been fabricated and characterized in a clock setup using coherent population trapping spectroscopy. The measured signals exhibit null power linewidths down to 2.23 kHz and high transmission contrasts up to 17%. A high contrast-to-linewidth ratio is found at a linewidth of 4.17 kHz and a contrast of 5.2% in a 7-mm-long cell despite a beam diameter reduced to 600 μm. PMID:26365754

  9. Laser light routing in an elongated micromachined vapor cell with diffraction gratings for atomic clock applications.

    PubMed

    Chutani, Ravinder; Maurice, Vincent; Passilly, Nicolas; Gorecki, Christophe; Boudot, Rodolphe; Abdel Hafiz, Moustafa; Abbé, Philippe; Galliou, Serge; Rauch, Jean-Yves; de Clercq, Emeric

    2015-09-14

    This paper reports on an original architecture of microfabricated alkali vapor cell designed for miniature atomic clocks. The cell combines diffraction gratings with anisotropically etched single-crystalline silicon sidewalls to route a normally-incident beam in a cavity oriented along the substrate plane. Gratings have been specifically designed to diffract circularly polarized light in the first order, the latter having an angle of diffraction matching the (111) sidewalls orientation. Then, the length of the cavity where light interacts with alkali atoms can be extended. We demonstrate that a longer cell allows to reduce the beam diameter, while preserving the clock performances. As the cavity depth and the beam diameter are reduced, collimation can be performed in a tighter space. This solution relaxes the constraints on the device packaging and is suitable for wafer-level assembly. Several cells have been fabricated and characterized in a clock setup using coherent population trapping spectroscopy. The measured signals exhibit null power linewidths down to 2.23 kHz and high transmission contrasts up to 17%. A high contrast-to-linewidth ratio is found at a linewidth of 4.17 kHz and a contrast of 5.2% in a 7-mm-long cell despite a beam diameter reduced to 600 μm.

  10. Two-Photon Microscopy with Diffractive Optical Elements and Spatial Light Modulators

    PubMed Central

    Watson, Brendon O.; Nikolenko, Volodymyr; Araya, Roberto; Peterka, Darcy S.; Woodruff, Alan; Yuste, Rafael

    2010-01-01

    Two-photon microscopy is often performed at slow frame rates due to the need to serially scan all points in a field of view with a single laser beam. To overcome this problem, we have developed two optical methods that split and multiplex a laser beam across the sample. In the first method a diffractive optical element (DOE) generates a fixed number of beamlets that are scanned in parallel resulting in a corresponding increase in speed or in signal-to-noise ratio in time-lapse measurements. The second method uses a computer-controlled spatial light modulator (SLM) to generate any arbitrary spatio-temporal light pattern. With an SLM one can image or photostimulate any predefined region of the image such as neurons or dendritic spines. In addition, SLMs can be used to mimic a large number of optical transfer functions including light path corrections as adaptive optics. PMID:20859526

  11. Two-photon microscopy with diffractive optical elements and spatial light modulators.

    PubMed

    Watson, Brendon O; Nikolenko, Volodymyr; Araya, Roberto; Peterka, Darcy S; Woodruff, Alan; Yuste, Rafael

    2010-01-01

    Two-photon microscopy is often performed at slow frame rates due to the need to serially scan all points in a field of view with a single laser beam. To overcome this problem, we have developed two optical methods that split and multiplex a laser beam across the sample. In the first method a diffractive optical element (DOE) generates a fixed number of beamlets that are scanned in parallel resulting in a corresponding increase in speed or in signal-to-noise ratio in time-lapse measurements. The second method uses a computer-controlled spatial light modulator (SLM) to generate any arbitrary spatio-temporal light pattern. With an SLM one can image or photostimulate any predefined region of the image such as neurons or dendritic spines. In addition, SLMs can be used to mimic a large number of optical transfer functions including light path corrections as adaptive optics.

  12. Light-induced structural changes in a photosynthetic reaction center caught by Laue diffraction.

    PubMed

    Wöhri, Annemarie B; Katona, Gergely; Johansson, Linda C; Fritz, Emelie; Malmerberg, Erik; Andersson, Magnus; Vincent, Jonathan; Eklund, Mattias; Cammarata, Marco; Wulff, Michael; Davidsson, Jan; Groenhof, Gerrit; Neutze, Richard

    2010-04-30

    Photosynthetic reaction centers convert the energy content of light into a transmembrane potential difference and so provide the major pathway for energy input into the biosphere. We applied time-resolved Laue diffraction to study light-induced conformational changes in the photosynthetic reaction center complex of Blastochloris viridis. The side chain of TyrL162, which lies adjacent to the special pair of bacteriochlorophyll molecules that are photooxidized in the primary light conversion event of photosynthesis, was observed to move 1.3 angstroms closer to the special pair after photoactivation. Free energy calculations suggest that this movement results from the deprotonation of this conserved tyrosine residue and provides a mechanism for stabilizing the primary charge separation reactions of photosynthesis.

  13. I19, the small-molecule single-crystal diffraction beamline at Diamond Light Source.

    PubMed

    Nowell, Harriott; Barnett, Sarah A; Christensen, Kirsten E; Teat, Simon J; Allan, David R

    2012-05-01

    The dedicated small-molecule single-crystal X-ray diffraction beamline (I19) at Diamond Light Source has been operational and supporting users for over three years. I19 is a high-flux tunable-wavelength beamline and its key details are described in this article. Much of the work performed on the beamline involves structure determination from small and weakly diffracting crystals. Other experiments that have been supported to date include structural studies at high pressure, studies of metastable species, variable-temperature crystallography, studies involving gas exchange in porous materials and structural characterizations that require analysis of the diffuse scattering between Bragg reflections. A range of sample environments to facilitate crystallographic studies under non-ambient conditions are available as well as a number of options for automation. An indication of the scope of the science carried out on the beamline is provided by the range of highlights selected for this paper.

  14. Theoretical Fraunhofer light diffraction patterns calculated from three-dimensional sarcomere arrays imaged from isolated cardiac cells at rest.

    PubMed

    Roos, K P; Leung, A F

    1987-08-01

    Sarcomere striation positions have been obtained throughout the volumes of calcium-tolerant resting heart cells by direct computer interfaced high-resolution optical imaging. Each sarcomere position is stored in a three-dimensional (3-D) matrix array from which Fraunhofer light diffraction patterns have been calculated using numerical methods based on Fourier transforms. Diffraction patterns have been calculated from heart cell data arrays oriented normal to a theoretical laser beam. Twelve characteristic features have been identified and described from these diffraction patterns that correlate to diffraction phenomena observed from both cardiac and skeletal muscle. This numerical approach provides the means to directly assess diffraction pattern formulation, the precision of layer line angular separation, layer-line intensity and angular asymmetries, line widths and fine structures in terms of the known diffracting source structures. These results confirm that theoretical calculations can predict real muscle diffraction patterns and their asymmetries.

  15. Coherent Soft X-ray Diffraction Imaging of Coliphage PR772 at the Linac Coherent Light Source

    DOE Data Explorer

    Reddy, Hemanth, K.N.

    2017-01-05

    A dataset of coherent soft X-ray diffraction images of Coliphage PR772 virus, collected at the Atomic Molecular Optics (AMO) beamline with pnCCD detectors in the LAMP instrument at the Linac Coherent Light Source.

  16. Total internal reflection ellipsometry: principles and applications.

    PubMed

    Arwin, Hans; Poksinski, Michal; Johansen, Knut

    2004-05-20

    A concept for a measurement technique based on ellipsometry in conditions of total internal reflection is presented. When combined with surface plasmon resonance (SPR) effects, this technique becomes powerful for monitoring and analyzing adsorption and desorption on thin semitransparent metal films as well as for analyzing the semitransparent films themselves. We call this technique total internal reflection ellipsometry (TIRE). The theory of ellipsometry under total internal reflection combined with SPR is discussed for some simple cases. For more advanced cases and to prove the concept, simulations are performed with the Fresnel formalism. The use of TIRE is exemplified by applications in protein adsorption, corrosion monitoring, and adsorption from opaque liquids on metal surfaces. Simulations and experiments show greatly enhanced thin-film sensitivity compared with ordinary ellipsometry.

  17. Novel light trapping concepts for crystalline silicon solar cells using diffractive rear side structures

    NASA Astrophysics Data System (ADS)

    Eisenlohr, J.; Tucher, N.; Bett, Alexander; Hauser, H.; Graf, M.; Benick, J.; Goldschmidt, J. C.; Bläsi, B.; Hermle, M.

    2014-05-01

    Crystalline silicon solar cells absorb light in the near infrared only weakly. To utilize also the infrared light of the solar spectrum with energies still greater than the band gap of silicon, the effective path of the light inside the solar cell has to be enhanced. Light paths can be manipulated at the front side as well as at the rear side of a solar cell. For the front side, pyramidal textures that also show anti-reflection properties are widely used. These anti-reflection properties, however, can also be achieved with planar dielectric coatings or nanostructured surfaces. In this case, the path length enhancement can be achieved with rear side structures that are especially optimized for this purpose, thus de-coupling anti-reflection and path-length enhancement functionalities. This de-coupling creates leeway to optimize not only the optical properties but also the electrical properties of the optically active structures, and to realize structures that are compatible with very thin silicon wafers. To this end, this paper investigates two kinds of diffractive rear side structures, both, theoretically and experimentally. First, hexagonal sphere gratings that are produced by a self-organized growth process using spin coating, and second, binary gratings produced via nano-imprint lithography. Both process chains are potentially scalable to large areas. In optical measurements we determined potential photocurrent density gains of over 1 mA/cm2 for 250 μm thick wafers for both structures. Furthermore, we developed a process for contact formation as one key step to fully processed solar cells with diffractive rear side structures.

  18. Efficient photonic reformatting of celestial light for diffraction-limited spectroscopy

    NASA Astrophysics Data System (ADS)

    MacLachlan, D. G.; Harris, R. J.; Gris-Sánchez, I.; Morris, T. J.; Choudhury, D.; Gendron, E.; Basden, A. G.; Spaleniak, I.; Arriola, A.; Birks, T. A.; Allington-Smith, J. R.; Thomson, R. R.

    2017-02-01

    The spectral resolution of a dispersive astronomical spectrograph is limited by the trade-off between throughput and the width of the entrance slit. Photonic guided wave transitions have been proposed as a route to bypass this trade-off, by enabling the efficient reformatting of incoherent seeing-limited light collected by the telescope into a linear array of single modes: a pseudo-slit which is highly multimode in one axis but diffraction-limited in the dispersion axis of the spectrograph. It is anticipated that the size of a single-object spectrograph fed with light in this manner would be essentially independent of the telescope aperture size. A further anticipated benefit is that such spectrographs would be free of `modal noise', a phenomenon that occurs in high-resolution multimode fibre-fed spectrographs due to the coherent nature of the telescope point spread function (PSF). We seek to address these aspects by integrating a multicore fibre photonic lantern with an ultrafast laser inscribed three-dimensional waveguide interconnect to spatially reformat the modes within the PSF into a diffraction-limited pseudo-slit. Using the CANARY adaptive optics (AO) demonstrator on the William Herschel Telescope, and 1530 ± 80 nm stellar light, the device exhibits a transmission of 47-53 per cent depending upon the mode of AO correction applied. We also show the advantage of using AO to couple light into such a device by sampling only the core of the CANARY PSF. This result underscores the possibility that a fully optimized guided-wave device can be used with AO to provide efficient spectroscopy at high spectral resolution.

  19. Spin-to-orbit conversion at acousto-optic diffraction of light: conservation of optical angular momentum.

    PubMed

    Skab, Ihor; Vlokh, Rostyslav

    2012-04-01

    Acousto-optic diffraction of light in optically active cubic crystals is analyzed from the viewpoint of conservation of optical angular momentum. It is shown that the availability of angular momentum in the diffracted optical beam can be necessarily inferred from the requirements of angular momentum conservation law. As follows from our analysis, a circularly polarized diffracted wave should bear an orbital angular momentum. The efficiency of the spin-to-orbit momentum conversion is governed by the efficiency of acousto-optic diffraction.

  20. IR sensitivity enhancement of CMOS Image Sensor with diffractive light trapping pixels.

    PubMed

    Yokogawa, Sozo; Oshiyama, Itaru; Ikeda, Harumi; Ebiko, Yoshiki; Hirano, Tomoyuki; Saito, Suguru; Oinoue, Takashi; Hagimoto, Yoshiya; Iwamoto, Hayato

    2017-06-19

    We report on the IR sensitivity enhancement of back-illuminated CMOS Image Sensor (BI-CIS) with 2-dimensional diffractive inverted pyramid array structure (IPA) on crystalline silicon (c-Si) and deep trench isolation (DTI). FDTD simulations of semi-infinite thick c-Si having 2D IPAs on its surface whose pitches over 400 nm shows more than 30% improvement of light absorption at λ = 850 nm and the maximum enhancement of 43% with the 540 nm pitch at the wavelength is confirmed. A prototype BI-CIS sample with pixel size of 1.2 μm square containing 400 nm pitch IPAs shows 80% sensitivity enhancement at λ = 850 nm compared to the reference sample with flat surface. This is due to diffraction with the IPA and total reflection at the pixel boundary. The NIR images taken by the demo camera equip with a C-mount lens show 75% sensitivity enhancement in the λ = 700-1200 nm wavelength range with negligible spatial resolution degradation. Light trapping CIS pixel technology promises to improve NIR sensitivity and appears to be applicable to many different image sensor applications including security camera, personal authentication, and range finding Time-of-Flight camera with IR illuminations.

  1. Three-dimensional shape measurement based on light patterns projection using diffractive optical elements

    NASA Astrophysics Data System (ADS)

    Twardowski, P.; Serio, B.; Raulot, V.; Guilhem, M.

    2010-05-01

    We propose a structured light micro-opto electromechanical system (MOEMS) projector specially designed to display successively a set of patterns in order to extract the 3-D shape of an object using a CCD cameras module and a small ARM-based computer for control, registration and numerical analysis. This method consists in a temporal codification using a modified Gray code combined with a classical phase shifting technique. Our approach is to combine the unambiguous and robust codification of the Gray code method with the high resolution of the phase shifting method to result in highly accurate 3D reconstructions. The proposed MOEMS is based on an array of vertical-cavity surface-emitting laser (VCSEL) combined with two planar static diffractive optical elements (DOEs) arrays. DOEs masters on quartz substrate have been fabricated using photolithography therefore replication in polycarbonate is possible at low cost. The first DOE array is designed to collimate the VCSEL light (Fresnel-type element) and the second one to project the codification patterns. DOEs have been designed and fabricated by surface etching to achieve a good diffraction efficiency using four phase levels. First we introduce the MEOMS principle and the features of the different components. We present the layout design of the DOEs and describe the issues related to the micro-fabrication process. An experimental study of the topography of the DOEs is presented and discussed. We then discuss fabrication aspects including the DOEs integration and packaging.

  2. Toward efficient light diffraction and intensity variations by using wide bandwidth surface acoustic wave

    NASA Astrophysics Data System (ADS)

    Lee, Young Ok; Chen, Fu; Lee, Kee Keun

    2016-06-01

    We have developed acoustic-optic (AO) based display units for implementing a handheld hologram display by modulating light deflection through wide bandwidth surface acoustic wave (SAW). The developed AO device consists of a metal layer, a ZnS waveguide layer, SAW inter digital transducers (IDTs), and a screen for display. When RF power with a particular resonant frequency was applied to IDTs, SAW was radiated and interfered with confined beam propagating along ZnS waveguide layer. The AO interacted beam was deflected laterally toward a certain direction depending on Bragg diffraction condition, exited out of the waveguide layer and then directed to the viewing screen placed at a certain distance from the device to form a single pixel. The deflected angles was adjusted by modulating the center frequency of the SAW IDT (SAW grating), the RF power of SAW, and the angles between propagating light beam path along waveguide and radiating SAW. The diffraction efficiency was also characterized in terms of waveguide thickness, SAW RF input power, and aperture length. Coupling of mode (COM) modeling was fulfilled to find optimal device parameters prior to fabrication. All the parameters affecting the deflection angle and efficiency to form a pixel for a three-dimensional (3D) hologram image were characterized and then discussed.

  3. Interaction of light with a metal wedge: the role of diffraction in shaping energy flow.

    PubMed

    Xi, Yonggang; Jung, Yun Suk; Kim, Hong Koo

    2010-02-01

    When a light wave hits a metal wedge structure, the metal surfaces respond to the incident light by generating both free-space and surface-bound waves. Here we present a physical model that elucidates electromagnetic interactions of an incoming planar wave with a simple semi-infinite 90 degrees metal wedge. We show that a metal wedge structure possesses an intrinsic capability of directing the incident power around the corner into the forward direction. Interplay of the boundary diffraction wave and the incident and reflection waves in the near field region of a metal corner is found to form a basis of the funneling phenomena that are commonly observed in metal nanoslit structures. Theory and experiment reveal that the incident wave propagating parallel to the sidewall destructively interferes with the boundary diffraction wave forming a depleted-energy-flow region along the glancing angle direction. A physical understanding of various electromagnetic phenomena associated with a metal wedge structure confirms rich potential of the simple structure as an elemental building block of complex metal nanostructures.

  4. Quantum-mechanical diffraction theory of light from a small hole: Extinction-theorem approach

    NASA Astrophysics Data System (ADS)

    Jung, Jesper; Keller, Ole

    2015-07-01

    In a recent paper [Phys. Rev. A 90, 043830 (2014), 10.1103/PhysRevA.90.043830] it was shown that the so-called aperture response tensor is the central concept in the microscopic quantum theory of light diffraction from a small hole in a flat screen. It was further shown that the quantum mechanical theory of diffraction only requires a preknowledge of the incident field plus the electronic properties of identical screens with and without a hole. Starting from the quantum mechanical expression for the linear conductivity tensor, we study the related causal conductivity tensor paying particular attention to diamagnetic electron dynamics. Using a nonlocal-potential separation assumption, we present a calculation of the diamagnetic causal surface conductivity for a jellium quantum-well screen using a two-dimensional Hartree-Fock model. In the diamagnetic case the difference between the light-unperturbed electron densities for screens with (n0) and without (n∞0) holes are the primary quantities for the diffraction theory. In a central part (Sec. IV) of this article we determine n0 via a quantum-mechanical two-dimensional extinction-theorem approach related to elastic electron scattering from a hole with an electronic selvedge. For heuristic purposes we illustrate aspects of the extinction-theorem theory by applying the approach for an infinitely high potential barrier to the vacuum hole. Finally, we calculate and discuss the aperture response tensor in the small hole limit and in the zeroth-order Born approximation. Our final result for the aperture response tensor establishes the bridge to the anisotropic electric dipole polarizability tensor of the hole. It turns out that the effective optical aperture (hole) size relates closely to the extension of the relevant electronic wave functions scattered from the hole.

  5. Capillary waves and ellipsometry experiments

    NASA Astrophysics Data System (ADS)

    Bonn, D.; Wegdam, G. H.

    1992-09-01

    The inclusion of higher-order terms in the capillary-wave Hamiltonian may reduce the contributions of these fluctuations to the ellipsometric coefficients. We show that the renormalization of capillary waves at a fluid-fluid interface by Sengers and van Leeuwen [Phys. Rev. A 39 (1989) 6346] using the wave vector-dependent surface tension that follows from the coupled mode theory by Meunier [Phys. France 48 (1987)1819] yields a satisfactory agreement with recent ellipsometry measurements by Schmidt [Phys. Rev. A 38 (1988) 567]. The interface is viewed upon as an intrinsic interface broadened by capillary waves. We suppose that the cutoff wave vector q_{max} that follows from mode-coupling theory marks the transition from the short-wavelength bulk-like fluctuations that contribute to the bare surface tension to the long-wavelength capillary wave-like fluctuations that contribute to the full surface tension. This enables us to calculate, without any adjustable parameters, both the ratio of the bare and experimental surface tension and the universal constant for the elliptical thickness of the interface. Both agree remarkably well with experimental values.

  6. Generalized phase contrast-enhanced diffractive coupling to light-driven microtools

    NASA Astrophysics Data System (ADS)

    Villangca, Mark; Bañas, Andrew; Palima, Darwin; Glückstad, Jesper

    2015-11-01

    We have previously demonstrated on-demand dynamic coupling to optically manipulated microtools coined as wave-guided optical waveguides using diffractive techniques on a "point and shoot" approach. These microtools are extended microstructures fabricated using two-photon photopolymerization and function as free-floating optically trapped waveguides. Dynamic coupling of focused light via these structures being moved in three-dimensional space is done holographically. However, calculating the necessary holograms is not straightforward when using counter-propagating trapping geometry. The generation of the coupling spots is done in real time following the position of each microtool with the aid of an object tracking routine. This approach allows continuous coupling of light through the microtools which can be useful in a variety of biophotonics applications. To complement the targeted-light delivery capability of the microtools, the applied spatial light modulator has been illuminated with a properly matched input beam cross section based on the generalized phase contrast method. Our results show a significant gain in the output at the tip of each microtool as measured from the fluorescence signal of the trapping medium. The ability to switch from on-demand to continuous addressing with efficient illumination leverages our microtools for potential applications in stimulation and near-field-based biophotonics on cellular scales.

  7. Progress on the prevention of stray light and diffraction effects on the Thai National Telescope

    NASA Astrophysics Data System (ADS)

    Buisset, Christophe; Prasit, Apirat; Leckngam, Apichat; Lépine, Thierry; Poshyajinda, Saran; Soonthornthum, Boonrucksar; Irawati, Puji; Richichi, Andrea; Sawangwit, Utane; Dhillon, Vik; Hardy, Liam K.

    2015-09-01

    The 2.4-m Thai National Telescope (TNT) is the main facility of the Thai National Observatory located on the Doi Inthanon, Thailand's highest mountain. The first astronomical images obtained at the TNT suffered from diffraction and stray light problems: bright spikes spread from bright stellar images over few arcminutes in the focal plane, and the images taken during observations in bright moon conditions were contaminated by high levels of stray light. We performed targeted investigations to identify the origin of these problems. In a first time, these investigations consisted of analyzing the irradiance distribution of defocused stellar images and of identifying the contributors. We concluded that these bright spikes around the bright stellar images were due to the chamfer and the wavefront error at the mirror edge. We thus installed an annular mask along the edge of the primary mirror that fully suppressed these spikes and we quantified the improvement by observing the double star Sirius. In a second time, we identified the contributors to the stray light by placing a pinhole camera at the TNT focal plane. Then, we designed a new baffle to improve the stray light rejection. The final design of the baffle comprises 21 diaphragms, is painted with an ordinary black paint and was designed, developed and installed on the TNT in less than 8 months. We assessed the improvement on the performance by measuring the variation of the stray light signal before and after installing the baffle in the telescope structure. These steps significantly improved the image quality and enhanced the rejection of the stray light at the focal plane level. In this paper, we present our investigations, we describe the method used to design the TNT baffle, and we present the improvement in quantitative terms.

  8. Sound Velocity and Diffraction Intensity Measurements Based on Raman-Nath Theory of the Interaction of Light and Ultrasound

    ERIC Educational Resources Information Center

    Neeson, John F.; Austin, Stephen

    1975-01-01

    Describes a method for the measurement of the velocity of sound in various liquids based on the Raman-Nath theory of light-sound interaction. Utilizes an analog computer program to calculate the intensity of light scattered into various diffraction orders. (CP)

  9. Sound Velocity and Diffraction Intensity Measurements Based on Raman-Nath Theory of the Interaction of Light and Ultrasound

    ERIC Educational Resources Information Center

    Neeson, John F.; Austin, Stephen

    1975-01-01

    Describes a method for the measurement of the velocity of sound in various liquids based on the Raman-Nath theory of light-sound interaction. Utilizes an analog computer program to calculate the intensity of light scattered into various diffraction orders. (CP)

  10. Determining Concentration of Nanoparticles from Ellipsometry

    NASA Technical Reports Server (NTRS)

    Venkatasubbarao, Srivatsa; Kempen, Lothar U.; Chipman, Russell

    2008-01-01

    A method of using ellipsometry or polarization analysis of light in total internal reflection of a surface to determine the number density of gold nanoparticles on a smooth substrate has been developed. The method can be modified to enable determination of densities of sparse distributions of nanoparticles in general, and is expected to be especially useful for measuring gold-nanoparticle-labeled biomolecules on microarrays. The method is based on theoretical calculations of the ellipsometric responses of gold nanoparticles. Elements of the calculations include the following: For simplicity, the gold nanoparticles are assumed to be spherical and to have the same radius. The distribution of gold nanoparticles is assumed to be a sub-monolayer (that is, sparser than a monolayer). The optical response of the sub-monolayer is modeled by use of a thin-island-film theory, according to which the polarizabilities parallel and perpendicular to the substrate are functions of the wavelength of light, the dielectric functions (permittivities expressed as complex functions of frequency or wavelength) of the gold and the suspending medium (in this case, the suspending medium is air), the fraction of the substrate area covered by the nanoparticles, and the radius of the nanoparticles. For the purpose of the thin-island-film theory, the dielectric function of the gold nanoparticles is modeled as the known dielectric function of bulk gold plus a correction term that is necessitated by the fact that the mean free path length for electrons in gold decreases with decreasing radius, in such a manner as to cause the imaginary part of the dielectric function to increase with decreasing radius (see figure). The correction term is a function of the nanoparticle radius, the wavelength of light, the mean free path and the Fermi speed of electrons in bulk gold, the plasma frequency of gold, and the speed of light in a vacuum. These models are used to calculate ellipsometric responses for

  11. Infrared ellipsometry of nanometric anisotropic dielectric layers on absorbing materials

    NASA Astrophysics Data System (ADS)

    Adamson, Peep

    2014-05-01

    An inversion problem of infrared ellipsometry is resolved on the basis of a fresh mathematical approach, which does not use the traditional regression analysis for data handling and has no need of initial guesses for the desired parameters. It is shown that obtained simple analytical equations for ellipsometric quantities open up new possibilities for determining optical parameters of an anisotropic ultrathin layer. The novel method possesses very high sensitivity because it is based on the phase conversion measurements of polarized reflected light. The method is tested using a numerical simulation and the results demonstrate clearly that it is successfully applicable for nanometric layers in the infrared spectral region.

  12. Assessing differences between Ostwald ripening and coalescence by rheology, laser diffraction and multiple light scattering.

    PubMed

    Santos, J; Calero, N; Trujillo-Cayado, L A; Garcia, M C; Muñoz, J

    2017-08-14

    This contribution deals with the study of the influence of surfactant ratio, namely triblock copolymer (Pluronic PE9400) to polyoxyethylene glycerol fatty acid ester (Levenol C201), on the stability of emulsions formulated with a mixture of two biosolvents (N,N Dimethyl Decanamide and D-limonene), which find applications as carriers of agrochemicals. Emulsions containing Pluronic, regardless of the concentration studied, underwent Ostwald ripening while coalescence controlled the destabilization process of emulsions containing Levenol C201 as the only emulsifier. The physical stability of the emulsions was analysed not only by means of mean diameters determined by laser diffraction but also with respect to their rheological properties and the so-called TSI parameter derived from multiple light scattering measurements with aging time. We propose that the different structures of both surfactants at the oil/water interface may be responsible for the occurrence of different destabilization mechanisms. It is likely that Copolymer Pluronic PE9400 formed multilayers in the emulsions studied, which may promote flocculation during processing and, subsequently, Ostwald ripening. In contrast, Levenol C201 probably formed a compact adsorbed layer with the molecules perpendicularly oriented to the interface. This work illustrates to what extent the combination of information provided by Multiple Light Scattering, rheology and laser diffraction enables the detection and monitoring of destabilization mechanisms such as Ostwald ripening and coalescence. In addition, this research highlights the importance of surfactant selection for the physical stability of emulsions that exhibited similar droplet size distributions just after preparation. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Modular sub-wavelength diffractive light modulator for high-definition holographic displays

    NASA Astrophysics Data System (ADS)

    Stahl, Richard; Rochus, Veronique; Rottenberg, Xavier; Cosemans, Stefan; Haspeslagh, Luc; Severi, Simone; Van der Plas, Geert; Lafruit, Gauthier; Donnay, Stephane

    2013-02-01

    Holography is undoubtedly the ultimate 3D visualization technology, offering true 3D experience with all the natural depth cues, without the undesirable side-effects of current stereoscopic systems (uncomfortable glasses, strained eyes, fatiguing experience). Realization of a high-definition holographic display however requires a number of breakthroughs from existing prototypes. One of the main challenges lies in technology scaling, as holography is based on light diffraction and interference - to achieve wide viewing angles, the light-modulating pixels need to be spaced close to or below the wavelength of the used visible light. Furthermore, achieving high 3D image quality, hundreds of millions of such individually programmable pixels are needed. As a solution, we develop a modular sub-wavelength light modulator, consisting of three main sub-systems: the optical sub-system, comprising a 2D array of sub-wavelength pixels; the driver sub-system for individual pixel control, and the holographic computational engine. Based on conclusions from our state-of-the art studies, numerous experiments and holographic demonstrators, we have focused on reflective phase-modulating MEMS-based system and its scaling beyond 500nm pitch. We have devised a unique binary-programmable phase-modulating pixel architecture realizing vertical pixel displacement of up to 150nm at 500nm by 500nm pixel pitch, while sustaining low operating voltages compatible with CMOS driver circuitry. IMEC SiGe MEMS technology enables integration of the CMOS pixel-line drivers, scan-line drivers and I/O circuits underneath the 2D MEMS array, resulting in a compact and modular single-chip system design. Refresh rates of few hundred frames per second are achieved using our patented segmented driver-array architecture. Integrated circuits implementing parallel holographic computational engines can be added to the module using advanced 3D stacking technology. Herein we further report on our progress in realizing

  14. Dynamic diffraction-limited light-coupling of 3D-maneuvered wave-guided optical waveguides.

    PubMed

    Villangca, Mark; Bañas, Andrew; Palima, Darwin; Glückstad, Jesper

    2014-07-28

    We have previously proposed and demonstrated the targeted-light delivery capability of wave-guided optical waveguides (WOWs). As the WOWs are maneuvered in 3D space, it is important to maintain efficient light coupling through the waveguides within their operating volume. We propose the use of dynamic diffractive techniques to create diffraction-limited spots that will track and couple to the WOWs during operation. This is done by using a spatial light modulator to encode the necessary diffractive phase patterns to generate the multiple and dynamic coupling spots. The method is initially tested for a single WOW and we have experimentally demonstrated dynamic tracking and coupling for both lateral and axial displacements.

  15. Light beam diffraction on inhomogeneous holographic photonic PDLC structures under the influence of spatially non-uniform electric field

    NASA Astrophysics Data System (ADS)

    Semkin, A. O.; Sharangovich, S. N.

    2016-08-01

    In this work the theoretical model of two-dimensional Bragg diffraction of quasimonochromatic light beams on amplitude- and phase- inhomogeneous holographic photonic PDLC structures under the impact of spatially non-uniform electric field is proposed. The selfconsistent solutions for the light diffraction on PDLC structure with uniform amplitude and quasi-quadratic profiles are obtained for the case of influence of linearly varying electric field. The possibility to compensate the PDLC structure response inhomogeneity by the impact of non-unifrom external field is shown.

  16. Intensity of light diffraction from striated muscle as a function of incident angle.

    PubMed Central

    Baskin, R J; Lieber, R L; Oba, T; Yeh, Y

    1981-01-01

    In a recently developed theory of light diffraction by single striated muscle fibers, we considered only the case of normal beam incidence. The present investigation represents both an experimental and theoretical extension of the previous work to arbitrary incident angle. Angle scan profiles over a 50 degrees range of incident angle (+25 degrees to -25 degrees) were obtained at different sarcomere lengths. Left and right first-order scan peak separations were found to be a function of sarcomere length (separation angle = 2 theta B), and good agreement was found between theory and experiment. Our theoretical analysis further showed that a myofibrillar population with a single common skew angle can yield an angle scan profile containing many peaks. Thus, it is not necessary to associate each peak with a different skew population. Finally, we have found that symmetry angle, theta s, also varies with sarcomere length, but not in a regular manner. Its value at a given sarcomere length is a function of a particular region of a given fiber and represents the average skew angle of all the myofibril populations illuminated. The intensity of a diffraction order line is considered to be principally the resultant of two interference phenomena. The first is a volume-grating phenomenon which results from the periodic A-I band structure of the fiber (with some contribution from Z bands and H zones). The second is Bragg reflection from skew planes, if the correct relation between incident angle and skew angle is met. This may result in intensity asymmetry between the left and right first order lines. PMID:6976802

  17. Rotatable broadband retarders for far infrared spectroscopic ellipsometry

    SciTech Connect

    Kang, T.D.; Carr, G.; Zhou, T.; Kotelyanskii, M.; Sirenko, A.A.

    2010-12-09

    Rotatable retarders have been developed for applications in spectroscopic, full Mueller Matrix ellipsometry in the far-IR spectral range. Several materials, such as silicon, KRS-5, and a commercial polymer plastic (TOPAS) have been utilized to achieve a fully adjustable retardation between 0{sup o} and 90{sup o}. Experimental characteristics of the rotatable retarders that utilize three- and four-bounce designs are compared with calculations. We discuss the effect of light focusing on the performance of these rotatable retarders. Broadband optical retarders are required for spectroscopic ellipsometry in its full Mueller matrix (MM) realization. Performance of the MM ellipsometer depends on the capability to produce substantially linearly-independent Stokes vectors for the light incident onto the sample. As has been shown, the errors in the measuredMMof the sample are proportional to the condition number of the 4 x 4 matrix composed of the Stokes vectors of four polarization states incident at the sample. It can be proven that it is impossible to cover the Poincare sphere with linearly-independent Stokes vectors by only changing the linear polarization at the input surface of a stationary retarder. As we will illustrate further in this paper, total coverage of the Poincare sphere is possible by rotating a tandem of a linear polarizer and a retarder with a retardation of 90{sup o}. It is this goal that we are trying to achieve in the retarder designs described in this paper.

  18. Sensing of Streptococcus mutans by microscopic imaging ellipsometry

    NASA Astrophysics Data System (ADS)

    Khaleel, Mai Ibrahim; Chen, Yu-Da; Chien, Ching-Hang; Chang, Yia-Chung

    2017-05-01

    Microscopic imaging ellipsometry is an optical technique that uses an objective and sensing procedure to measure the ellipsometric parameters Ψ and Δ in the form of microscopic maps. This technique is well known for being noninvasive and label-free. Therefore, it can be used to detect and characterize biological species without any impact. Microscopic imaging ellipsometry was used to measure the optical response of dried Streptococcus mutans cells on a glass substrate. The ellipsometric Ψ and Δ maps were obtained with the Optrel Multiskop system for specular reflection in the visible range (λ=450 to 750 nm). The Ψ and Δ images at 500, 600, and 700 nm were analyzed using three different theoretical models with single-bounce, two-bounce, and multibounce light paths to obtain the optical constants and height distribution. The obtained images of the optical constants show different aspects when comparing the single-bounce analysis with the two-bounce or multibounce analysis in detecting S. mutans samples. Furthermore, the height distributions estimated by two-bounce and multibounce analyses of S. mutans samples were in agreement with the thickness values measured by AFM, which implies that the two-bounce and multibounce analyses can provide information complementary to that obtained by a single-bounce light path.

  19. Photochromism and diffraction grating in cyanoazobenzene polymer films

    NASA Astrophysics Data System (ADS)

    Serwadczak, M.; Wübbenhorst, M.; Kucharski, S.

    2006-08-01

    Two series of photochromic copolymathacrylates containing cyanoazobenzene chromophores as side chains were described. The series with shorter ethylene spacer between mesogen and main polymethacrylate chain was amorphous, whereas the second one with longer ethoxyethylene spacer was liquid crystalline forming smectic C mesophase above Tg. The materials were deposited on glass substrates via spin coating and casting technique to provide thin transparent films. The reversible change of refractive index of the films on illumination with white light was determined by ellipsometry. The difference of real part of the refractive index of the sample was in the range 0.0067-0.0210 depending on the polymer. Formation of diffraction grating was achieved by two beam coupling arrangement using a 532 nm laser diode . The diffraction efficiency for the first order diffraction was in the range of 1.5-2.1% for the homopolymers.

  20. Thermo-driven light controller by using thermal modulation of diffraction wavelength in holographic polymer dispersed liquid crystal grating

    NASA Astrophysics Data System (ADS)

    Ogiwara, Akifumi; Kakiuchida, Hiroshi

    2014-02-01

    A microperiodic structure composed of polymer and liquid crystal (LC) phases, called holographic polymer dispersed liquid crystal (HPDLC), was fabricated based on a photo-induced phase separation technique by laser interferometric exposure. The diffraction wavelength of HPDLC gratings formed by different LC composites and grating structures was experimentally investigated by spectroscopic measurements as a function of temperature at around 30 °C. The HPDLC gratings composed of nematic LC having low nematic to isotropic temperature (TNI) and film thickness of 25 μm showed the switch of diffraction wavelength between visible and infrared lights by the change of temperature. The optical characteristics achieved in HPDLC gratings are expected to be applicable for the basis of diffractive type of thermodriven light controller which can supply visibility constantly for solar-ray control windows.

  1. Optical diffraction tomography microscopy with transport of intensity equation using a light-emitting diode array

    NASA Astrophysics Data System (ADS)

    Li, Jiaji; Chen, Qian; Zhang, Jialin; Zhang, Zhao; Zhang, Yan; Zuo, Chao

    2017-08-01

    Optical diffraction tomography (ODT) is an effective label-free technique for quantitatively refractive index imaging, which enables long-term monitoring of the internal three-dimensional (3D) structures and molecular composition of biological cells with minimal perturbation. However, existing optical tomographic methods generally rely on interferometric configuration for phase measurement and sophisticated mechanical systems for sample rotation or beam scanning. Thereby, the measurement is suspect to phase error coming from the coherent speckle, environmental vibrations, and mechanical error during data acquisition process. To overcome these limitations, we present a new ODT technique based on non-interferometric phase retrieval and programmable illumination emitting from a light-emitting diode (LED) array. The experimental system is built based on a traditional bright field microscope, with the light source replaced by a programmable LED array, which provides angle-variable quasi-monochromatic illumination with an angular coverage of ±37 degrees in both x and y directions (corresponding to an illumination numerical aperture of ∼0.6). Transport of intensity equation (TIE) is utilized to recover the phase at different illumination angles, and the refractive index distribution is reconstructed based on the ODT framework under first Rytov approximation. The missing-cone problem in ODT is addressed by using the iterative non-negative constraint algorithm, and the misalignment of the LED array is further numerically corrected to improve the accuracy of refractive index quantification. Experiments on polystyrene beads and thick biological specimens show that the proposed approach allows accurate refractive index reconstruction while greatly reduced the system complexity and environmental sensitivity compared to conventional interferometric ODT approaches.

  2. Multimodal Spectral Imaging of Cells Using a Transmission Diffraction Grating on a Light Microscope

    PubMed Central

    Isailovic, Dragan; Xu, Yang; Copus, Tyler; Saraswat, Suraj; Nauli, Surya M.

    2011-01-01

    A multimodal methodology for spectral imaging of cells is presented. The spectral imaging setup uses a transmission diffraction grating on a light microscope to concurrently record spectral images of cells and cellular organelles by fluorescence, darkfield, brightfield, and differential interference contrast (DIC) spectral microscopy. Initially, the setup was applied for fluorescence spectral imaging of yeast and mammalian cells labeled with multiple fluorophores. Fluorescence signals originating from fluorescently labeled biomolecules in cells were collected through triple or single filter cubes, separated by the grating, and imaged using a charge-coupled device (CCD) camera. Cellular components such as nuclei, cytoskeleton, and mitochondria were spatially separated by the fluorescence spectra of the fluorophores present in them, providing detailed multi-colored spectral images of cells. Additionally, the grating-based spectral microscope enabled measurement of scattering and absorption spectra of unlabeled cells and stained tissue sections using darkfield and brightfield or DIC spectral microscopy, respectively. The presented spectral imaging methodology provides a readily affordable approach for multimodal spectral characterization of biological cells and other specimens. PMID:21639978

  3. High throughput imaging of blood smears using white light diffraction phase microscopy

    NASA Astrophysics Data System (ADS)

    Majeed, Hassaan; Kandel, Mikhail E.; Bhaduri, Basanta; Han, Kevin; Luo, Zelun; Tangella, Krishnarao; Popescu, Gabriel

    2015-03-01

    While automated blood cell counters have made great progress in detecting abnormalities in blood, the lack of specificity for a particular disease, limited information on single cell morphology and intrinsic uncertainly due to high throughput in these instruments often necessitates detailed inspection in the form of a peripheral blood smear. Such tests are relatively time consuming and frequently rely on medical professionals tally counting specific cell types. These assays rely on the contrast generated by chemical stains, with the signal intensity strongly related to staining and preparation techniques, frustrating machine learning algorithms that require consistent quantities to denote the features in question. Instead we opt to use quantitative phase imaging, understanding that the resulting image is entirely due to the structure (intrinsic contrast) rather than the complex interplay of stain and sample. We present here our first steps to automate peripheral blood smear scanning, in particular a method to generate the quantitative phase image of an entire blood smear at high throughput using white light diffraction phase microscopy (wDPM), a single shot and common path interferometric imaging technique.

  4. Electron diffraction studies of light-induced conformational changes in the Leu-93 --> Ala bacteriorhodopsin mutant.

    PubMed

    Subramaniam, S; Faruqi, A R; Oesterhelt, D; Henderson, R

    1997-03-04

    We previously have presented evidence for prominent structural changes in helices F and G of bacteriorhodopsin during the photocycle. These changes were determined by carrying out electron diffraction analysis of illuminated two-dimensional crystals of wild-type bacteriorhodopsin or the Asp-96 --> Gly mutant that were trapped at a stage in the photocycle after light-driven proton release, but preceding proton uptake from the aqueous medium. Here, we report structural analysis of the long-lived O intermediate observed in the photocycle of the Leu-93 --> Ala mutant, which accumulates after the release and uptake of protons, but before the reisomerization of retinal to its initial all-trans state. Projection Fourier difference maps show that upon illumination of the Leu-93 --> Ala mutant, significant structural changes occur in the vicinity of helices C, B, and G, and to a lesser extent near helix F. Our results suggest that (i) all four helices that line the proton channel (B, C, F, and G) participate in structural changes during the late stages of the photocycle, and (ii) completion of the photocycle involves significant conformational changes in addition to those that are associated with steps in proton transport.

  5. Creation of Sub-diffraction Longitudinally Polarized Spot by Focusing Radially Polarized Light with Binary Phase Lens.

    PubMed

    Yu, An-Ping; Chen, Gang; Zhang, Zhi-Hai; Wen, Zhong-Quan; Dai, Lu-Ru; Zhang, Kun; Jiang, Sen-Lin; Wu, Zhi-Xiang; Li, Yu-Yan; Wang, Chang-Tao; Luo, Xian-Gang

    2016-12-12

    The generation of a sub-diffraction longitudinally polarized spot is of great interest in various applications, such as optical tweezers, super-resolution microscopy, high-resolution Raman spectroscopy, and high-density optical data storage. Many theoretical investigations have been conducted into the tight focusing of a longitudinally polarized spot with high-numerical-aperture aplanatic lenses in combination with optical filters. Optical super-oscillation provides a new approach to focusing light beyond the diffraction limit. Here, we propose a planar binary phase lens and experimentally demonstrate the generation of a longitudinally polarized sub-diffraction focal spot by focusing radially polarized light. The lens has a numerical aperture of 0.93 and a long focal length of 200λ for wavelength λ = 632.8 nm, and the generated focal spot has a full-width-at-half-maximum of about 0.456λ, which is smaller than the diffraction limit, 0.54λ. A 5λ-long longitudinally polarized optical needle with sub-diffraction size is also observed near the designed focal point.

  6. Creation of Sub-diffraction Longitudinally Polarized Spot by Focusing Radially Polarized Light with Binary Phase Lens

    PubMed Central

    Yu, An-ping; Chen, Gang; Zhang, Zhi-hai; Wen, Zhong-quan; Dai, Lu-ru; Zhang, Kun; Jiang, Sen-lin; Wu, Zhi-xiang; Li, Yu-yan; Wang, Chang-tao; Luo, Xian-gang

    2016-01-01

    The generation of a sub-diffraction longitudinally polarized spot is of great interest in various applications, such as optical tweezers, super-resolution microscopy, high-resolution Raman spectroscopy, and high-density optical data storage. Many theoretical investigations have been conducted into the tight focusing of a longitudinally polarized spot with high-numerical-aperture aplanatic lenses in combination with optical filters. Optical super-oscillation provides a new approach to focusing light beyond the diffraction limit. Here, we propose a planar binary phase lens and experimentally demonstrate the generation of a longitudinally polarized sub-diffraction focal spot by focusing radially polarized light. The lens has a numerical aperture of 0.93 and a long focal length of 200λ for wavelength λ = 632.8 nm, and the generated focal spot has a full-width-at-half-maximum of about 0.456λ, which is smaller than the diffraction limit, 0.54λ. A 5λ-long longitudinally polarized optical needle with sub-diffraction size is also observed near the designed focal point. PMID:27941852

  7. Image quality affected by diffraction of aperture structure arrangement in transparent active-matrix organic light-emitting diode displays.

    PubMed

    Tsai, Yu-Hsiang; Huang, Mao-Hsiu; Jeng, Wei-de; Huang, Ting-Wei; Lo, Kuo-Lung; Ou-Yang, Mang

    2015-10-01

    Transparent display is one of the main technologies in next-generation displays, especially for augmented reality applications. An aperture structure is attached on each display pixel to partition them into transparent and black regions. However, diffraction blurs caused by the aperture structure typically degrade the transparent image when the light from a background object passes through finite aperture window. In this paper, the diffraction effect of an active-matrix organic light-emitting diode display (AMOLED) is studied. Several aperture structures have been proposed and implemented. Based on theoretical analysis and simulation, the appropriate aperture structure will effectively reduce the blur. The analysis data are also consistent with the experimental results. Compared with the various transparent aperture structure on AMOLED, diffraction width (zero energy position of diffraction pattern) of the optimize aperture structure can be reduced 63% and 31% in the x and y directions in CASE 3. Associated with a lenticular lens on the aperture structure, the improvement could reach to 77% and 54% of diffraction width in the x and y directions. Modulation transfer function and practical images are provided to evaluate the improvement of image blurs.

  8. Creation of Sub-diffraction Longitudinally Polarized Spot by Focusing Radially Polarized Light with Binary Phase Lens

    NASA Astrophysics Data System (ADS)

    Yu, An-Ping; Chen, Gang; Zhang, Zhi-Hai; Wen, Zhong-Quan; Dai, Lu-Ru; Zhang, Kun; Jiang, Sen-Lin; Wu, Zhi-Xiang; Li, Yu-Yan; Wang, Chang-Tao; Luo, Xian-Gang

    2016-12-01

    The generation of a sub-diffraction longitudinally polarized spot is of great interest in various applications, such as optical tweezers, super-resolution microscopy, high-resolution Raman spectroscopy, and high-density optical data storage. Many theoretical investigations have been conducted into the tight focusing of a longitudinally polarized spot with high-numerical-aperture aplanatic lenses in combination with optical filters. Optical super-oscillation provides a new approach to focusing light beyond the diffraction limit. Here, we propose a planar binary phase lens and experimentally demonstrate the generation of a longitudinally polarized sub-diffraction focal spot by focusing radially polarized light. The lens has a numerical aperture of 0.93 and a long focal length of 200λ for wavelength λ = 632.8 nm, and the generated focal spot has a full-width-at-half-maximum of about 0.456λ, which is smaller than the diffraction limit, 0.54λ. A 5λ-long longitudinally polarized optical needle with sub-diffraction size is also observed near the designed focal point.

  9. Degeneration of Fraunhofer diffraction on bacterial colonies due to their light focusing properties examined in the digital holographic microscope system.

    PubMed

    Buzalewicz, Igor; Liżewski, Kamil; Kujawińska, Małgorzata; Podbielska, Halina

    2013-11-04

    The degeneration of Fraunhofer diffraction conditions in the optical system with converging spherical wave illumination for bacteria species identification based on diffraction patterns is analyzed by digital holographic methods. The obtained results have shown that the colonies of analyzed bacteria species act as biological lenses with the time-dependent light focusing properties, which are characterized and monitored by means of phase retrieval from sequentially captured digital holograms. This significantly affects the location of Fraunhofer patterns observation plane, which is continuously shifted across optical axis in time.

  10. The study of diffractive lenses displayed in a phase-only liquid crystal spatial light modulator

    NASA Astrophysics Data System (ADS)

    Ma, Si-jin; Panezai, Spozmai; Wang, Da-yong; Wang, Yun-xin; Rong, Lu

    2013-08-01

    Phase-only spatial light modulator (SLM) based on liquid crystal on silicon (LCOS) is a kind of device based on electrically controlled birefringence effect to realize phase modulation. Due to its low cost, programmable, high resolution, fast response time, LCOS has been widely used in multi-channel imaging, adaptive optics, diffraction optical elements (DOEs), dynamic holographic, optical tweezers and other fields. It is necessary to numerically evaluate the modulation characterization of LCOS before application. Firstly, the phase modulation characterization of the LCOS (PLUTO HED6010XXX by Holoeye Company) was measured based on the Twyman-Green interferometer, and the curves of both phase shift and normalized intensity as grey level functions were obtained. Experimental results indicated that phase modulation of the LCOS could be achieved to 3.99π, and the root-mean-square value (RMS) of normalized intensity was less than 0.01, which demonstrated that LCOS could be regarded as a phase-only modulation device. This method is also suitable for the evaluation of modulation characterization of other LCOS devices. Secondly, a phase pattern of thin lens written onto LCOS was demonstrated. Because of the pixel structure of LCOS, the theory of discretization of lenses was studied. Both simulation and experimental results were obtained. The experimental results proved that the convergence character of the lens written onto LCOS was similar to optical lenses. In the experiment, the measured focal length was in a good agreement to the theoretical deduction, and the relative error (RE) of which was below 1%. Both simulation and experimental results showed that LCOS could be used as lens to converge the plane wave, and replace the optical lens successfully.

  11. New method for determination of diffraction light pattern of the arbitrary surface

    NASA Astrophysics Data System (ADS)

    Stevanovic, N.; Markovic, V. M.; Nikezic, D.

    2017-05-01

    Diffraction phenomena have a special importance in optics. Due to their complex nature, diffraction problems cannot be solved exactly using an analytical approach for the general case. Problems for which an exact analytical solution can be found are reduced to simple ones, with a great deal of symmetry of obstacles and slits where the diffraction occurs. On the other hand, numerical methods can be very useful in solving particular problems where parameters of obstacles or slits are known. These methods can be applied in cases when the screen is at a short distance (Fresnel diffraction) as well as at a large distance (Fraunhofer diffraction). In this paper, the methodology for finding a solution in case of diffraction problem on arbitrary objects which are at an arbitrary distance from the screen is presented. The method is based on numerical solving of the Fresnel-Kirchhoff integral by means of discretization of an obstacle and the screen on which the diffraction pattern is observed. This method can be applied for arbitrary shapes of slits for which the equation of the surface is known as well as for an arbitrary positioned screen, located even very close to the object. The developed method is employed to determine the diffraction pattern for obstacles for which the pattern is already known from the theory. Good agreement was found.

  12. IN SITU ELLIPSOMETRY FOR SHOCK COMPRESSION MEASUREMENTS

    SciTech Connect

    Bakshi, L.; Eliezer, S.; Appelbaum, G.; Nissim, N.; Perelmutter, L.; Mond, M.

    2009-12-28

    Knowledge about the optical properties of materials at high pressure and high temperature is needed for EOS research. Ellipsometry measures the change in the polarization of a probe beam reflected from a surface. From the change in polarization, the real and imaginary parts of the time dependent complex index of refraction can be extracted. From the measured optical properties, fundamental physical properties of the material, such as emissivity, phase transitions, and electrical conductivity can be extracted. A dynamic ellipsometry measurement system with nanosecond resolution was built in order to measure all four stocks parameters. Gas gun was used to accelerate the impact flyer. Our experiments concentrated on the optical properties of 1020 steel targets with impact pressure range of 40-250 kbar. Although there are intrinsic difficulties with dynamic ellipsometric measurements, distinct changes were observed for 1020 steel under shock compression larger than 130 kbar, the alpha->epsilon phase transition.

  13. Jet Fuel Thermal Stability Investigations using Ellipsometry

    NASA Technical Reports Server (NTRS)

    Nash, Leigh; Klettlinger, Jennifer; Vasu, Subith

    2017-01-01

    Ellipsometry is an optical technique used to measure the thickness of thin films. This technique was used to measure the thickness of deposits created by heated jet fuel, specifically Sasol IPK on stainless steel tubes. A new amorphous model was used to iteratively determine the film thickness. This method was found to be repeatable, and the thickness of deposit increased with increasing temperature and increasing concentration of naphthalene.

  14. Coherent diffraction of single Rice Dwarf virus particles using hard X-rays at the Linac Coherent Light Source.

    PubMed

    Munke, Anna; Andreasson, Jakob; Aquila, Andrew; Awel, Salah; Ayyer, Kartik; Barty, Anton; Bean, Richard J; Berntsen, Peter; Bielecki, Johan; Boutet, Sébastien; Bucher, Maximilian; Chapman, Henry N; Daurer, Benedikt J; DeMirci, Hasan; Elser, Veit; Fromme, Petra; Hajdu, Janos; Hantke, Max F; Higashiura, Akifumi; Hogue, Brenda G; Hosseinizadeh, Ahmad; Kim, Yoonhee; Kirian, Richard A; Reddy, Hemanth K N; Lan, Ti-Yen; Larsson, Daniel S D; Liu, Haiguang; Loh, N Duane; Maia, Filipe R N C; Mancuso, Adrian P; Mühlig, Kerstin; Nakagawa, Atsushi; Nam, Daewoong; Nelson, Garrett; Nettelblad, Carl; Okamoto, Kenta; Ourmazd, Abbas; Rose, Max; van der Schot, Gijs; Schwander, Peter; Seibert, M Marvin; Sellberg, Jonas A; Sierra, Raymond G; Song, Changyong; Svenda, Martin; Timneanu, Nicusor; Vartanyants, Ivan A; Westphal, Daniel; Wiedorn, Max O; Williams, Garth J; Xavier, Paulraj Lourdu; Yoon, Chun Hong; Zook, James

    2016-08-01

    Single particle diffractive imaging data from Rice Dwarf Virus (RDV) were recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS). RDV was chosen as it is a well-characterized model system, useful for proof-of-principle experiments, system optimization and algorithm development. RDV, an icosahedral virus of about 70 nm in diameter, was aerosolized and injected into the approximately 0.1 μm diameter focused hard X-ray beam at the CXI instrument of LCLS. Diffraction patterns from RDV with signal to 5.9 Ångström were recorded. The diffraction data are available through the Coherent X-ray Imaging Data Bank (CXIDB) as a resource for algorithm development, the contents of which are described here.

  15. Coherent diffraction of single Rice Dwarf virus particles using hard X-rays at the Linac Coherent Light Source

    PubMed Central

    Munke, Anna; Andreasson, Jakob; Aquila, Andrew; Awel, Salah; Ayyer, Kartik; Barty, Anton; Bean, Richard J.; Berntsen, Peter; Bielecki, Johan; Boutet, Sébastien; Bucher, Maximilian; Chapman, Henry N.; Daurer, Benedikt J.; DeMirci, Hasan; Elser, Veit; Fromme, Petra; Hajdu, Janos; Hantke, Max F.; Higashiura, Akifumi; Hogue, Brenda G.; Hosseinizadeh, Ahmad; Kim, Yoonhee; Kirian, Richard A.; Reddy, Hemanth K.N.; Lan, Ti-Yen; Larsson, Daniel S.D.; Liu, Haiguang; Loh, N. Duane; Maia, Filipe R.N.C.; Mancuso, Adrian P.; Mühlig, Kerstin; Nakagawa, Atsushi; Nam, Daewoong; Nelson, Garrett; Nettelblad, Carl; Okamoto, Kenta; Ourmazd, Abbas; Rose, Max; van der Schot, Gijs; Schwander, Peter; Seibert, M. Marvin; Sellberg, Jonas A.; Sierra, Raymond G.; Song, Changyong; Svenda, Martin; Timneanu, Nicusor; Vartanyants, Ivan A.; Westphal, Daniel; Wiedorn, Max O.; Williams, Garth J.; Xavier, Paulraj Lourdu; Yoon, Chun Hong; Zook, James

    2016-01-01

    Single particle diffractive imaging data from Rice Dwarf Virus (RDV) were recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS). RDV was chosen as it is a well-characterized model system, useful for proof-of-principle experiments, system optimization and algorithm development. RDV, an icosahedral virus of about 70 nm in diameter, was aerosolized and injected into the approximately 0.1 μm diameter focused hard X-ray beam at the CXI instrument of LCLS. Diffraction patterns from RDV with signal to 5.9 Ångström were recorded. The diffraction data are available through the Coherent X-ray Imaging Data Bank (CXIDB) as a resource for algorithm development, the contents of which are described here. PMID:27478984

  16. Coherent diffraction of single Rice Dwarf virus particles using hard X-rays at the Linac Coherent Light Source

    SciTech Connect

    Munke, Anna; Andreasson, Jakob; Aquila, Andrew; Awel, Salah; Ayyer, Kartik; Barty, Anton; Bean, Richard J.; Berntsen, Peter; Bielecki, Johan; Boutet, Sebastien; Bucher, Maximilian; Chapman, Henry N.; Daurer, Benedikt J.; DeMirci, Hasan; Elser, Veit; Fromme, Petra; Hajdu, Janos; Hantke, Max F.; Higashiura, Akifumi; Hogue, Brenda G.; Hosseinizadeh, Ahmad; Kim, Yoonhee; Kirian, Richard A.; Reddy, Hemanth K. N.; Lan, Ti -Yen; Larsson, Daniel S. D.; Liu, Haiguang; Loh, N. Duane; Maia, Filipe R. N. C.; Mancuso, Adrian P.; Muhlig, Kerstin; Nakagawa, Atsushi; Nam, Daewoong; Nelson, Garrett; Nettelblad, Carl; Okamoto, Kenta; Ourmazd, Abbas; Rose, Max; van der Schot, Gijs; Schwander, Peter; Seibert, M. Marvin; Sellberg, Jonas A.; Sierra, Raymond G.; Song, Changyong; Svenda, Martin; Timneanu, Nicusor; Vartanyants, Ivan A.; Westphal, Daniel; Wiedorn, Max O.; Williams, Garth J.; Xavier, Paulraj Lourdu; Yoon, Chun Hong; Zook, James

    2016-08-01

    Single particle diffractive imaging data from Rice Dwarf Virus (RDV) were recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS). RDV was chosen as it is a well-characterized model system, useful for proof-of-principle experiments, system optimization and algorithm development. RDV, an icosahedral virus of about 70 nm in diameter, was aerosolized and injected into the approximately 0.1 μm diameter focused hard X-ray beam at the CXI instrument of LCLS. Diffraction patterns from RDV with signal to 5.9 Ångström were recorded. Here, the diffraction data are available through the Coherent X-ray Imaging Data Bank (CXIDB) as a resource for algorithm development, the contents of which are described here.

  17. Coherent diffraction of single Rice Dwarf virus particles using hard X-rays at the Linac Coherent Light Source

    DOE PAGES

    Munke, Anna; Andreasson, Jakob; Aquila, Andrew; ...

    2016-08-01

    Single particle diffractive imaging data from Rice Dwarf Virus (RDV) were recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS). RDV was chosen as it is a well-characterized model system, useful for proof-of-principle experiments, system optimization and algorithm development. RDV, an icosahedral virus of about 70 nm in diameter, was aerosolized and injected into the approximately 0.1 μm diameter focused hard X-ray beam at the CXI instrument of LCLS. Diffraction patterns from RDV with signal to 5.9 Ångström were recorded. Here, the diffraction data are available through the Coherent X-ray Imaging Data Bank (CXIDB)more » as a resource for algorithm development, the contents of which are described here.« less

  18. FUNDAMENTAL AREAS OF PHENOMENOLOGY (INCLUDING APPLICATIONS): In-Situ Characterization of Three-Dimensional Optical Matters by Light Diffraction

    NASA Astrophysics Data System (ADS)

    Jiang, Lai-Dong; Dai, Qiao-Feng; Feng, Tian-Hua; Liu, Jin; Wu, Li-Jun; Lan, Sheng; Gopal V., A.; Trofimov A., V.

    2009-07-01

    Three-dimensional optical matters are created by combining the single beam optical trapping with the conventional Z-scan technique. Dynamic light diffraction is employed to evaluate the structure and quality of the optical matter formed at the optimum trapping power. The lattice constant of the optical matter is extracted based on the Bragg and Snell laws, showing that polystyrene spheres are nearly close-packed in the optical matter, confirmed by comparing the diffraction pattern of the optical matter with that of a colloidal photonic crystal fabricated by the self-assembled technique. The relatively broad diffraction peaks observed in the optical matter indicate that the density of disorders in it is higher than that in the photonic crystal. It is suggested that the optical matter possesses a random close-packed structure rather than a face centered cubic one.

  19. Spectroscopic ellipsometry and polarimetry for materials and systems analysis at the nanometer scale: state-of-the-art, potential, and perspectives

    PubMed Central

    Bergmair, Michael; Bruno, Giovanni; Cattelan, Denis; Cobet, Christoph; de Martino, Antonello; Fleischer, Karsten; Dohcevic-Mitrovic, Zorana; Esser, Norbert; Galliet, Melanie; Gajic, Rados; Hemzal, Dušan; Hingerl, Kurt; Humlicek, Josef; Ossikovski, Razvigor; Popovic, Zoran V.; Saxl, Ottilia

    2009-01-01

    This paper discusses the fundamentals, applications, potential, limitations, and future perspectives of polarized light reflection techniques for the characterization of materials and related systems and devices at the nanoscale. These techniques include spectroscopic ellipsometry, polarimetry, and reflectance anisotropy. We give an overview of the various ellipsometry strategies for the measurement and analysis of nanometric films, metal nanoparticles and nanowires, semiconductor nanocrystals, and submicron periodic structures. We show that ellipsometry is capable of more than the determination of thickness and optical properties, and it can be exploited to gain information about process control, geometry factors, anisotropy, defects, and quantum confinement effects of nanostructures. PMID:21170135

  20. Microstructured Air Cavities as High-Index Contrast Substrates with Strong Diffraction for Light-Emitting Diodes.

    PubMed

    Moon, Yoon-Jong; Moon, Daeyoung; Jang, Jeonghwan; Na, Jin-Young; Song, Jung-Hwan; Seo, Min-Kyo; Kim, Sunghee; Bae, Dukkyu; Park, Eun Hyun; Park, Yongjo; Kim, Sun-Kyung; Yoon, Euijoon

    2016-05-11

    Two-dimensional high-index-contrast dielectric gratings exhibit unconventional transmission and reflection due to their morphologies. For light-emitting devices, these characteristics help guided modes defeat total internal reflections, thereby enhancing the outcoupling efficiency into an ambient medium. However, the outcoupling ability is typically impeded by the limited index contrast given by pattern media. Here, we report strong-diffraction, high-index-contrast cavity engineered substrates (CESs) in which hexagonally arranged hemispherical air cavities are covered with a 80 nm thick crystallized alumina shell. Wavelength-resolved diffraction measurements and Fourier analysis on GaN-grown CESs reveal that the high-index-contrast air/alumina core/shell patterns lead to dramatic excitation of the low-order diffraction modes. Large-area (1075 × 750 μm(2)) blue-emitting InGaN/GaN light-emitting diodes (LEDs) fabricated on a 3 μm pitch CES exhibit ∼39% enhancement in the optical power compared to state-of-the-art, patterned-sapphire-substrate LEDs, while preserving all of the electrical metrics that are relevant to LED devices. Full-vectorial simulations quantitatively demonstrate the enhanced optical power of CES LEDs and show a progressive increase in the extraction efficiency as the air cavity volume is expanded. This trend in light extraction is observed for both lateral- and flip-chip-geometry LEDs. Measurements of far-field profiles indicate a substantial beaming effect for CES LEDs, despite their few-micron-pitch pattern. Near-to-far-field transformation simulations and polarization analysis demonstrate that the improved extraction efficiency of CES LEDs is ascribed to the increase in emissions via the top escape route and to the extraction of transverse-magnetic polarized light.

  1. Reverse color sequence in the diffraction of white light by the wing of the male butterfly Pierella luna (Nymphalidae: Satyrinae).

    PubMed

    Vigneron, Jean Pol; Simonis, Priscilla; Aiello, Annette; Bay, Annick; Windsor, Donald M; Colomer, Jean-François; Rassart, Marie

    2010-08-01

    The butterfly Pierella luna (Nymphalidae) shows an intriguing rainbow iridescence effect: the forewings of the male, when illuminated along the axis from the body to the wing tip, decompose a white light beam as a diffraction grating would do. Violet light, however, emerges along a grazing angle, near the wing surface, while the other colors, from blue to red, exit respectively at angles progressively closer to the direction perpendicular to the wing plane. This sequence is the reverse of the usual decomposition of light by a grating with a periodicity parallel to the wing surface. It is shown that this effect is produced by a macroscopic deformation of the entire scale, which curls in such a way that it forms a "vertical" grating, perpendicular to the wing surface, and functions in transmission instead of reflection.

  2. ALS-II, a Potential Soft X-ray, Diffraction Limited Upgrade of the Advanced Light Source

    NASA Astrophysics Data System (ADS)

    Tarawneh, H.; Steier, C.; Falcone, R.; Robin, D.; Nishimura, H.; Sun, C.; Wan, W.

    2014-03-01

    The Advanced Light Source (ALS) at Berkeley Lab has seen many upgrades over the years, keeping it one of the brightest sources for soft x-rays worldwide. Recent developments in magnet technology and lattice design appear to open the door for very large further increases in brightness [1], particularly by reducing the horizontal emittance, even within the space constraints of the existing tunnel. Initial studies for possible lattices will be presented that could approach the soft x-ray diffraction limit around 2 keV in both planes within the ALS footprint. Emerging scientific applications and experimental methods that would greatly benefit from ring based sources having much higher brightness and transverse coherence than present or near future storage ring facilities include nanometer imaging applications, X-ray correlation spectroscopy, diffraction microscopy, holography, ptychography, and resonant inelastic soft X-ray scattering at high resolution.

  3. Coherent soft X-ray diffraction imaging of coliphage PR772 at the Linac coherent light source.

    PubMed

    Reddy, Hemanth K N; Yoon, Chun Hong; Aquila, Andrew; Awel, Salah; Ayyer, Kartik; Barty, Anton; Berntsen, Peter; Bielecki, Johan; Bobkov, Sergey; Bucher, Maximilian; Carini, Gabriella A; Carron, Sebastian; Chapman, Henry; Daurer, Benedikt; DeMirci, Hasan; Ekeberg, Tomas; Fromme, Petra; Hajdu, Janos; Hanke, Max Felix; Hart, Philip; Hogue, Brenda G; Hosseinizadeh, Ahmad; Kim, Yoonhee; Kirian, Richard A; Kurta, Ruslan P; Larsson, Daniel S D; Duane Loh, N; Maia, Filipe R N C; Mancuso, Adrian P; Mühlig, Kerstin; Munke, Anna; Nam, Daewoong; Nettelblad, Carl; Ourmazd, Abbas; Rose, Max; Schwander, Peter; Seibert, Marvin; Sellberg, Jonas A; Song, Changyong; Spence, John C H; Svenda, Martin; Van der Schot, Gijs; Vartanyants, Ivan A; Williams, Garth J; Xavier, P Lourdu

    2017-06-27

    Single-particle diffraction from X-ray Free Electron Lasers offers the potential for molecular structure determination without the need for crystallization. In an effort to further develop the technique, we present a dataset of coherent soft X-ray diffraction images of Coliphage PR772 virus, collected at the Atomic Molecular Optics (AMO) beamline with pnCCD detectors in the LAMP instrument at the Linac Coherent Light Source. The diameter of PR772 ranges from 65-70 nm, which is considerably smaller than the previously reported ~600 nm diameter Mimivirus. This reflects continued progress in XFEL-based single-particle imaging towards the single molecular imaging regime. The data set contains significantly more single particle hits than collected in previous experiments, enabling the development of improved statistical analysis, reconstruction algorithms, and quantitative metrics to determine resolution and self-consistency.

  4. Coherent soft X-ray diffraction imaging of coliphage PR772 at the Linac coherent light source

    PubMed Central

    Reddy, Hemanth K.N.; Yoon, Chun Hong; Aquila, Andrew; Awel, Salah; Ayyer, Kartik; Barty, Anton; Berntsen, Peter; Bielecki, Johan; Bobkov, Sergey; Bucher, Maximilian; Carini, Gabriella A.; Carron, Sebastian; Chapman, Henry; Daurer, Benedikt; DeMirci, Hasan; Ekeberg, Tomas; Fromme, Petra; Hajdu, Janos; Hanke, Max Felix; Hart, Philip; Hogue, Brenda G.; Hosseinizadeh, Ahmad; Kim, Yoonhee; Kirian, Richard A.; Kurta, Ruslan P.; Larsson, Daniel S.D.; Duane Loh, N.; Maia, Filipe R.N.C.; Mancuso, Adrian P.; Mühlig, Kerstin; Munke, Anna; Nam, Daewoong; Nettelblad, Carl; Ourmazd, Abbas; Rose, Max; Schwander, Peter; Seibert, Marvin; Sellberg, Jonas A.; Song, Changyong; Spence, John C.H.; Svenda, Martin; Van der Schot, Gijs; Vartanyants, Ivan A.; Williams, Garth J.; Xavier, P. Lourdu

    2017-01-01

    Single-particle diffraction from X-ray Free Electron Lasers offers the potential for molecular structure determination without the need for crystallization. In an effort to further develop the technique, we present a dataset of coherent soft X-ray diffraction images of Coliphage PR772 virus, collected at the Atomic Molecular Optics (AMO) beamline with pnCCD detectors in the LAMP instrument at the Linac Coherent Light Source. The diameter of PR772 ranges from 65–70 nm, which is considerably smaller than the previously reported ~600 nm diameter Mimivirus. This reflects continued progress in XFEL-based single-particle imaging towards the single molecular imaging regime. The data set contains significantly more single particle hits than collected in previous experiments, enabling the development of improved statistical analysis, reconstruction algorithms, and quantitative metrics to determine resolution and self-consistency. PMID:28654088

  5. Tunable diffraction grating using ultraviolet-light-induced spatial phase modulation in dual-frequency liquid crystal

    SciTech Connect

    Lin, P.-T.; Liang Xiao; Ren Hongwen; Wu, S.-T.

    2004-08-16

    An electrically tunable diffraction phase grating using ultraviolet (UV)-light-induced spatial dielectric modulation of a dual-frequency liquid crystal (DFLC) cell is demonstrated. A photomask with transparent and opaque stripes was used for fabricating the grating. In the UV-exposed stripes, the negative dielectric anisotropy ({delta}{epsilon}) tolane compound of the DFLC mixture is partially polymerized resulting in a decreased threshold voltage as compared to that of the unexposed region. Upon applying a constant voltage, the phase difference between the adjacent pixels is produced. The first-order diffraction efficiency reaches {approx}60% which agrees well with the simulation results. Due to the dual-frequency addressing at 30 V{sub rms}, the response time of the DFLC phase grating was measured to be {approx}1 ms at room temperature.

  6. Near-diffraction-limited annular flattop beam shaping with dual phase only liquid crystal spatial light modulators.

    PubMed

    Ma, Haotong; Zhou, Pu; Wang, Xiaolin; Ma, Yanxing; Xi, Fengjie; Xu, Xiaojun; Liu, Zejin

    2010-04-12

    We demonstrate the annular flattop beam shaping technique with dual phase only liquid crystal spatial light modulators (LC-SLM) based on the refractive laser beam shaping systems. One LC-SLM redistributes the intensity distribution, and the other restores the initial underlying wave front. Differing from the conventional annular beam shaping technique, the wave front of the output beam can be maintained. The influences of deviations of beam waist and beam shape on the output beam profile are discussed in detail. Experimental results show that approximate 71% of the power is enclosed in a region with less than 7% rms intensity variation. The 4.1mm diameter near-diffraction-limited beam retains an annular flattop intensity distribution without significant diffraction peaks for a working distance of more than 24cm in the near field.

  7. Coherent soft X-ray diffraction imaging of coliphage PR772 at the Linac coherent light source

    DOE PAGES

    Reddy, Hemanth K. N.; Yoon, Chun Hong; Aquila, Andrew; ...

    2017-06-27

    Single-particle diffraction from X-ray Free Electron Lasers offers the potential for molecular structure determination without the need for crystallization. In an effort to further develop the technique, we present a dataset of coherent soft X-ray diffraction images of Coliphage PR772 virus, collected at the Atomic Molecular Optics (AMO) beamline with pnCCD detectors in the LAMP instrument at the Linac Coherent Light Source. The diameter of PR772 ranges from 65–70 nm, which is considerably smaller than the previously reported ~600 nm diameter Mimivirus. This reflects continued progress in XFEL-based single-particle imaging towards the single molecular imaging regime. As a result, themore » data set contains significantly more single particle hits than collected in previous experiments, enabling the development of improved statistical analysis, reconstruction algorithms, and quantitative metrics to determine resolution and self-consistency.« less

  8. Suppression of the zero-order diffracted beam from a pixelated spatial light modulator by phase compression.

    PubMed

    Liang, Jinyang; Wu, Sih-Ying; Fatemi, Fredrik K; Becker, Michael F

    2012-06-01

    Phase compression is used to suppress the on-axis zero-order diffracted (ZOD) beam from a pixelated phase-only spatial light modulator (SLM) by a simple modification to the computer generated hologram (CGH) loaded onto the SLM. After CGH design, the phase of each SLM element is identically compressed by multiplying by a constant scale factor and rotated on the complex unit-circle to produce a cancellation beam that destructively interferes with the ZOD beam. Experiments achieved a factor of 3 reduction of the ZOD beam using two different liquid-crystal SLMs. Numerical simulation analyzed the reconstructed image quality and diffraction efficiency versus degree of phase compression and showed that phase compression resulted in little image degradation or power loss.

  9. Orbital motion of spherical microparticles trapped in diffraction patterns of circularly polarized light

    SciTech Connect

    Adachi, Hiroto; Akahoshi, Shin; Miyakawa, Kenji

    2007-06-15

    We investigate arrays and rotation of spherical microparticles trapped by focusing a circularly polarized Gaussian beam just above the top coverslip-water interface. Particles are trapped in various patterns due to a Fresnel diffraction, such as rings and close-packed structures. We find that rings of particles orbit around the beam axis, whereas close-packed arrays spin in the opposite sense on the beam axis. The sense of the orbiting, as well as that of the spinning, is determined by the input circular polarization handedness. The results are interpreted on the assumption that the spin angular momentum carried by a circularly polarized beam is converted into the orbital angular momentum in the optical process by which the focused Gaussian beam's shape is transformed due to diffraction.

  10. Application of diffraction tomography theory to determine size and shape of spheroidal particles from light scattering

    NASA Astrophysics Data System (ADS)

    Ding, Chizhu; Yang, Kecheng; Li, Wei; Guo, Wenping; Zhang, Xiaohui; Xia, Min

    2014-10-01

    Discerning the geometry of spheroidal scatterers of micron order is an important topic in identifying marine microbes. Optical diffraction tomography theory indicates that under the first-order Born approximation for weak scattering, scattering amplitude in the far zone and scattering potential of the scatterer have a Fourier relationship. In this paper, we describe a method based on diffraction tomography theory and determine the size and the shape of spheroidal scatterers by reconstructing the distribution of scattering potential from angular resolved scattered field. As a demonstration of this method, the scattering from spheroidal particles with equal-volume-sphere radii of 0.5429, 1.00, and 2.00 μm and an aspect ratio that varies from 0.4 to 1.5 was modeled by using T-matrix theory and used as test data. Simulation results show that in the case of low contrast, size and shape determination can be achieved with sub-wavelength precision.

  11. Mueller matrix imaging ellipsometry for nanostructure metrology.

    PubMed

    Liu, Shiyuan; Du, Weichao; Chen, Xiuguo; Jiang, Hao; Zhang, Chuanwei

    2015-06-29

    In order to achieve effective process control, fast, inexpensive, nondestructive and reliable nanometer scale feature measurements are extremely useful in high-volume nanomanufacturing. Among the possible techniques, optical scatterometry is relatively ideal due to its high throughput, low cost, and minimal sample damage. However, this technique is inherently limited by the illumination spot size of the instrument and the low efficiency in construction of a map of the sample over a wide area. Aiming at these issues, we introduce conventional imaging techniques to optical scatterometry and combine them with Mueller matrix ellipsometry based scatterometry, which is expected to be a powerful tool for the measurement of nanostructures in future high-volume nanomanufacturing, and propose to apply Mueller matrix imaging ellipsometry (MMIE) for nanostructure metrology. Two kinds of nanostructures were measured using an in-house developed Mueller matrix imaging ellipsometer in this work. The experimental results demonstrate that we can achieve Mueller matrix measurement and analysis for nanostructures with pixel-sized illumination spots by using MMIE. We can also efficiently construct parameter maps of the nanostructures over a wide area with pixel-sized lateral resolution by performing parallel ellipsometric analysis for all the pixels of interest.

  12. The photoelectric effect and study of the diffraction of light: Two new experiments in UNILabs virtual and remote laboratories network

    NASA Astrophysics Data System (ADS)

    Pedro Sánchez, Juan; Sáenz, Jacobo; de la Torre, Luis; Carreras, Carmen; Yuste, Manuel; Heradio, Rubén; Dormido, Sebastián

    2016-05-01

    This work describes two experiments: "study of the diffraction of light: Fraunhofer approximation" and "the photoelectric effect". Both of them count with a virtual, simulated, version of the experiment as well as with a real one which can be operated remotely. The two previous virtual and remote labs (built using Easy Java(script) Simulations) are integrated in UNILabs, a network of online interactive laboratories based on the free Learning Management System Moodle. In this web environment, students can find not only the virtual and remote labs but also manuals with related theory, the user interface description for each application, and so on.

  13. Note: Current induced fluctuations in the orientation of the beam diffracted by a liquid crystal spatial light modulator

    NASA Astrophysics Data System (ADS)

    Konwar, Santanu; Boruah, Bosanta R.

    2017-06-01

    In this paper, we report a peculiar movement of the beam cross sections associated with both the diffracted and undiffracted laser beams from a liquid crystal spatial light modulator (LCSLM). The beam movement becomes noticeable when the beam position is monitored continuously for several hours. We perform experiments to show that the beam movement is non-mechanical in nature and is connected with the power on/off instants of the LCSLM as well as the heat conductivity of the mounting slab which acts as the rigid support to the LCSLM panel. We also present a detailed analysis of the experimental findings to ascertain the possible cause of the beam fluctuations.

  14. Temperature dependent x-ray diffraction study of lightly doped Na{sub x}WO{sub 3}

    SciTech Connect

    Paul, Sanhita; Mukherjee, G. D.; Ghosh, Anirudha; Raj, Satyabrata; Oishi, S.

    2011-03-21

    Temperature dependent x-ray diffraction studies have been carried out on nonstoichiometric lightly doped sodium tungsten bronze (Na{sub x}WO{sub 3} for x=0.025). The investigation reveals a structural modification around 230 K. Although the high and low temperature phases are monoclinic but at low temperature the corner sharing WO{sub 6} octahedra get significantly distorted due to displacement of tungsten and oxygen atoms from its mean position. This structural modification induces polaron formation in Na{sub 0.025}WO{sub 3} below 230 K.

  15. CONTROLLING THE CHARACTERISTICS OF LASER LIGHT: Correlation of quantum intensity fluctuations in Raman-Nath diffraction

    NASA Astrophysics Data System (ADS)

    Alodzhants, A. P.; Arakelyan, S. M.; Kryukchan, G. Yu

    1993-07-01

    A new method of generating correlated fluctuations in optical fields, based on Raman-Nath diffraction by a fine grating, is discussed. A nonclassical effect is predicted: a suppression of quantum fluctuations below the level of full coherence in the sum or difference photon numbers for the transmitted and scattered waves. The physics of this phenomenon involves a correlation of quantum fluctuations in the intensities of two modes that are coupled nonlinearly. This correlation is most effective in the limit of parametric interaction between the waves in the medium.

  16. 7 Å resolution in protein two-dimensional-crystal X-ray diffraction at Linac Coherent Light Source

    PubMed Central

    Pedrini, Bill; Tsai, Ching-Ju; Capitani, Guido; Padeste, Celestino; Hunter, Mark S.; Zatsepin, Nadia A.; Barty, Anton; Benner, W. Henry; Boutet, Sébastien; Feld, Geoffrey K.; Hau-Riege, Stefan P.; Kirian, Richard A.; Kupitz, Christopher; Messerschmitt, Marc; Ogren, John I.; Pardini, Tommaso; Segelke, Brent; Williams, Garth J.; Spence, John C. H.; Abela, Rafael; Coleman, Matthew; Evans, James E.; Schertler, Gebhard F. X.; Frank, Matthias; Li, Xiao-Dan

    2014-01-01

    Membrane proteins arranged as two-dimensional crystals in the lipid environment provide close-to-physiological structural information, which is essential for understanding the molecular mechanisms of protein function. Previously, X-ray diffraction from individual two-dimensional crystals did not represent a suitable investigational tool because of radiation damage. The recent availability of ultrashort pulses from X-ray free-electron lasers (XFELs) has now provided a means to outrun the damage. Here, we report on measurements performed at the Linac Coherent Light Source XFEL on bacteriorhodopsin two-dimensional crystals mounted on a solid support and kept at room temperature. By merging data from about a dozen single crystal diffraction images, we unambiguously identified the diffraction peaks to a resolution of 7 Å, thus improving the observable resolution with respect to that achievable from a single pattern alone. This indicates that a larger dataset will allow for reliable quantification of peak intensities, and in turn a corresponding increase in the resolution. The presented results pave the way for further XFEL studies on two-dimensional crystals, which may include pump–probe experiments at subpicosecond time resolution. PMID:24914166

  17. Vectorial algorithm for the computation of light propagation equation based on Huygens' principle using the scalar theory of diffraction

    NASA Astrophysics Data System (ADS)

    Morucci, Stephane; Noirard, Pierre; Grossetie, Jean-Claude

    1996-03-01

    In digital holography, computation of holograms is often reduced to calculations of fast Fourier transforms if the distance between the object plane and the hologram plane is large enough. Two classical approximations for solving this problem include a binomial series expansion of the distance and an elimination of the so-called inclination factor. We present here a vectorial algorithm which computes the discrete form of the light propagation equation obtained by the Huygens' principle for a bidimensional object. None of the approximations mentioned above have been used. This enables the computation of a diffraction pattern at any distance compatible with the scalar theory of diffraction. This vectorial algorithm has been implemented on workstations, on a Convex C-220 and on a Cray YMP computer. We focus our attention on the computing granularity of the problem and we present processing times and the associated performances for bidimensional images. Various holograms are computed and compared with those obtained by two traditional methods, namely, Fresnel transforms and the resolution of the rigorous scalar diffraction equation using discrete convolutions. We then consider the 3D case and modifications are proposed in order to parallelize this algorithm.

  18. Ghost imaging and ghost diffraction with pseudo-thermal light generated by means of a programmable SLM

    NASA Astrophysics Data System (ADS)

    Capeluto, M. G.; Duisterwinkel, H.; Schmiegelow, C. T.; Francisco, D.; Ledesma, S.; Iemmi, C.

    2011-01-01

    Ghost imaging and ghost diffraction are techniques in which information about the object or about its diffraction pattern is extracted by measuring the correlation between a reference beam and a beam that passes through the object. Although first experiments were carried on by using entangled photons, it was demonstrated that this technique can be performed by splitting incoherent pseudo-thermal radiation such as that obtained with a laser passing through a moving diffuser. In this work we implemented the use of a programmable phase spatial light modulator (SLM) in order to replace the rotating ground glass. In this way the random phase distributions obtained from the moving diffuser can be emulated by displaying onto the SLM different realizations of a random function with uniform distribution. Based on the programmability of the modulator we have studied the influence of diverse parameters such as speckle size or phase distributions in the final image quality. We carry on the experiment for two different cases ghost imaging and far field ghost diffraction.

  19. 7 Å resolution in protein two-dimensional-crystal X-ray diffraction at Linac Coherent Light Source.

    PubMed

    Pedrini, Bill; Tsai, Ching-Ju; Capitani, Guido; Padeste, Celestino; Hunter, Mark S; Zatsepin, Nadia A; Barty, Anton; Benner, W Henry; Boutet, Sébastien; Feld, Geoffrey K; Hau-Riege, Stefan P; Kirian, Richard A; Kupitz, Christopher; Messerschmitt, Marc; Ogren, John I; Pardini, Tommaso; Segelke, Brent; Williams, Garth J; Spence, John C H; Abela, Rafael; Coleman, Matthew; Evans, James E; Schertler, Gebhard F X; Frank, Matthias; Li, Xiao-Dan

    2014-07-17

    Membrane proteins arranged as two-dimensional crystals in the lipid environment provide close-to-physiological structural information, which is essential for understanding the molecular mechanisms of protein function. Previously, X-ray diffraction from individual two-dimensional crystals did not represent a suitable investigational tool because of radiation damage. The recent availability of ultrashort pulses from X-ray free-electron lasers (XFELs) has now provided a means to outrun the damage. Here, we report on measurements performed at the Linac Coherent Light Source XFEL on bacteriorhodopsin two-dimensional crystals mounted on a solid support and kept at room temperature. By merging data from about a dozen single crystal diffraction images, we unambiguously identified the diffraction peaks to a resolution of 7 Å, thus improving the observable resolution with respect to that achievable from a single pattern alone. This indicates that a larger dataset will allow for reliable quantification of peak intensities, and in turn a corresponding increase in the resolution. The presented results pave the way for further XFEL studies on two-dimensional crystals, which may include pump-probe experiments at subpicosecond time resolution. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  20. Optical properties of InN studied by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Chunya, Ye; Wei, Lin; Jin, Zhou; Shuping, Li; Li, Chen; Heng, Li; Xiaoxuan, Wu; Songqing, Liu; Junyong, Kang

    2016-10-01

    With recently developed InN epitaxy via a controlling In bilayer, spectroscopic ellipsometry (SE) measurements had been carried out on the grown InN and the measured ellipsometric spectra were fitted with the Delta Psi2 software by using a suitable model and the dispersion rule. The thickness was measured by a scanning electron microscope (SEM). Insight into the film quality of InN and the lattice constant were gained by X-ray diffraction (XRD). By fitting the SE, the thickness of the InN film is consistent with that obtained by SEM cross-sectional thickness measurement. The optical bandgap of InN was put forward to be 1.05 eV, which conforms to the experimental results measured by the absorption spectrum and cathodoluminescence (CL). The refractive index and the extinction coefficient of interest were represented for InN, which is useful to design optoelectronic devices. Project supported by the State Key Development Program for Basic Research of China (No. 2012CB619301), the National High Technology Research and Development Program of China (No. 2014AA032608), the National Natural Science Foundation of China (Nos. 11204254, 11404271), and the Fundamental Research Funds for the Central Universities (Nos. 2012121014, 20720150027).

  1. Achieving an ultra-uniform diffraction pattern of stray light with metallic meshes by using ring and sub-ring arrays.

    PubMed

    Lu, Zhengang; Wang, Heyan; Tan, Jiubin; Ma, Limin; Lin, Shen

    2016-05-01

    We provide theoretical and experimental evidence that introducing metallic rings and sub-rings in mesh unit cells significantly decreases the high-order diffraction energy. Moreover, rotating the sub-rings results in increased uniformity in the diffraction distribution without affecting the transmittance. Experiments show that the triangular ring mesh with rotated sub-rings exhibits a normalized visible transmittance greater than 95% as well as an ultra-uniform diffraction pattern of stray light, whose maximal normalized high-order diffraction energy is lower than 0.0167%. This kind of metallic mesh will be favorable in transparent electromagnetic interference shielding devices and touch screens.

  2. Measurement of yarn twist based on backward light scattering and small-angle far-field diffraction

    NASA Astrophysics Data System (ADS)

    Pei, Z. G.; Tao, X. M.

    2015-12-01

    This paper presents a non-destructive, non-contact method for measuring the twist of a yarn based on light scattering and diffraction. The surface twist angle is measured by determining the direction of the line with the highest intensity on the backward light scattering pattern which is perpendicular to the surface fibers, which is verified by both theoretical analysis based on Beckmann’s scattering model and experiments. The yarn diameter is measured with good accuracy by using the small-angle far-field diffraction pattern of the yarn body. Yarn twist is then derived from the measured surface twist angle and yarn diameter. Further studies reveal that the measured yarn twists by the proposed method are comparable to those measured based on microscopic images of the yarn. This method requires no high-magnification optics and is able to pick up short-term variations of twist with less labor intensity, indicating its potential application in the on-line measuring of yarn twist and its distribution.

  3. Optimization of Light-Diffracting Photonic-Crystals for High Extraction Efficiency LEDs

    NASA Astrophysics Data System (ADS)

    David, Aurélien; Benisty, Henri; Weisbuch, Claude

    2007-06-01

    Photonic-crystal (PhC)-assisted light extraction is a promising method for ultrahigh efficiency, planar light-emitting diodes (LEDs). However, modeling of such structures is challenging due to the variety of their parameters and the heavy computational burden they represent. We present a thorough theoretical discussion of the optimization of PhC LEDs, which relies both on approximate treatments and on rigorous 3-D calculations. Two material systems (GaAs and GaN) are investigated, leading to quite different optimal regimes. Notably, it appears that besides the properties of the 2-D PhC itself, design of the vertical structure plays a major role in optimization.

  4. Efficiency and stray light measurements and calculations of diffraction gratings for the ALS

    SciTech Connect

    McKinney, W.R.; Mossessian, D.; Gullikson, E.; Heimann, P.

    1994-07-01

    Water cooled gratings manufactured for spherical grating monochromators of the Advanced Light Source beamlines 7.0, 8.0 and 9.0 were measured with the laser plasma source and reflectometer in the Center for X-ray Optics at LBL. The square-wave gratings are ion-milled into the polished electroless nickel surface after patterning by holographic photolithography. Absolute efficiency data are compared with exact electromagnetic theory calculation. Inter-order stray light and groove depths can be estimated from the measurements.

  5. Characterization on Smart Optics Using Ellipsometry

    NASA Technical Reports Server (NTRS)

    Song, Kyo D.

    2002-01-01

    Recently, NASA Langley Research Center developed a smart active optical concept to filter narrow band pass or to control optical intensity. To characterize developed smart optics materials, we have measured thickness and reflection properties of the materials using a WVASE32 ellipsometry. This project allowed us to: (1) prepare the smart optical materials for measurement of thickness and optical properties at NASA Langley Research Center; (2) measure thickness and optical properties of the smart optical materials; (3) evaluate the measured properties in terms of applications for narrow band-pass filters. The outcomes of this research provide optical properties and physical properties of the smart optics on a selected spectral range. The applications of this development were used for field-controlled spectral smart filters.

  6. Diffraction-Enhanced Computed Tomographic Imaging of Growing Piglet Joints by Using a Synchrotron Light Source

    PubMed Central

    Rhoades, Glendon W; Belev, George S; Chapman, L Dean; Wiebe, Sheldon P; Cooper, David M; Wong, Adelaine TF; Rosenberg, Alan M

    2015-01-01

    The objective of this project was to develop and test a new technology for imaging growing joints by means of diffraction-enhanced imaging (DEI) combined with CT and using a synchrotron radiation source. DEI–CT images of an explanted 4-wk-old piglet stifle joint were acquired by using a 40-keV beam. The series of scanned slices was later ‘stitched’ together, forming a 3D dataset. High-resolution DEI-CT images demonstrated fine detail within all joint structures and tissues. Striking detail of vasculature traversing between bone and cartilage, a characteristic of growing but not mature joints, was demonstrated. This report documents for the first time that DEI combined with CT and a synchrotron radiation source can generate more detailed images of intact, growing joints than can currently available conventional imaging modalities. PMID:26310464

  7. Controllable light diffraction in woodpile photonic crystals filled with liquid crystal

    SciTech Connect

    Ho, Chih-Hua; Zeng, Hao; Wiersma, Diederik S.; Cheng, Yu-Chieh; Maigyte, Lina; Trull, Jose; Cojocaru, Crina; Staliunas, Kestutis

    2015-01-12

    An approach to switching between different patterns of light beams transmitted through the woodpile photonic crystals filled with liquid crystals is proposed. The phase transition between the nematic and isotropic liquid crystal states leads to an observable variation of the spatial pattern transmitted through the photonic structure. The transmission profiles in the nematic phase also show polarization sensibility due to refractive index dependence on the field polarization. The experimental results are consistent with a numerical calculation by Finite Difference Time Domain method.

  8. Hybrid refractive/diffractive optical system design for light and compact uncooled longwave infrared imager

    NASA Astrophysics Data System (ADS)

    Wang, Hu; Bai, Yu; Luo, Jianjun

    2012-10-01

    Compares with traditional optics,the difractive optical element(DOE) has unique property of minus dispersion.The special state can be used in the optical system to improve performance,lighten weight and reduce volume effectively.In the paper,an infrared optical system with DOE for LWIR thermal imager is proposed.The primary optical parameters of thermal imager are wavelength range 8.0- 12.0μm,effective focal length (EFL) 150 mm,f/numbe 1.0 and field of view 8.58 degrees.The system uses uncooled infrared detector with 320×240 pixels and 45μm pixel size. The f/number matches the sensitivity range of detector array. The infrared optical system is designed by CODE-V optical design software.It is consisted of two lens,the materials of the two lenses are Germanium.The DOE is fabricated on the convex of the first lens and it can be fabricated by diamond turning technology.The imaging quafity of the optical system approached to diffraction limit.The value of modulation transfer function (MTF) at Nyquist frequency(11lp/mm) is great than 0.78.

  9. Development of a Compact Optical-MEMS Scanner with Integrated VCSEL Light Source and Diffractive Optics

    SciTech Connect

    Krygowski, Thomas W.; Reyes, David; Rodgers, M. Steven; Smith, James H.; Warren, Mial; Sweatt, William; Blum-Spahn, Olga; Wendt, Joel R.; Asbill, Randy

    1999-06-30

    In this work the design and initial fabrication results are reported for the components of a compact optical-MEMS laser scanning system. This system integrates a silicon MEMS laser scanner, a Vertical Cavity Surface Emitting Laser (VCSEL) and passive optical components. The MEMS scanner and VCSEL are mounted onto a fused silica substrate which serves as an optical interconnect between the devices. Two Diffractive Optical Elements (DOEs) are etched into the fused silica substrate to focus the VCSEL beam and increase the scan range. The silicon MEMS scanner consists of an actuator that continuously scans the position of a large polysilicon gold-coated shuttle containing a third DOE. Interferometric measurements show that the residual stress in the 500 {micro}m x 1000 {micro}m shuttle is extremely low, with a maximum deflection of only 0.18{micro}m over an 800 {micro}m span for an unmetallized case and a deflection of 0.56{micro}m for the metallized case. A conservative estimate for the scan range is {approximately}{+-}4{degree}, with a spot size of about 0.5 mm, producing 50 resolvable spots. The basic system architecture, optical and MEMS design is reported in this paper, with an emphasis on the design and fabrication of the silicon MEMS scanner portion of the system.

  10. Tomographic incoherent phase imaging, a diffraction tomography alternative for any white-light microscope

    NASA Astrophysics Data System (ADS)

    Bon, Pierre; Aknoun, Shérazade; Savatier, Julien; Wattellier, Benoit; Monneret, Serge

    2013-02-01

    In this paper, we discuss the possibility of making tomographic reconstruction of the refractive index of a microscopic sample using a quadriwave lateral shearing interferometer, under incoherent illumination. A Z-stack is performed and the acquired incoherent elecromagnetic fields are deconvoluted before to retrieve in a quantitative manner the refractive index. The results are presented on polystyrene beads and can easily be expanded to biological samples. This technique is suitable to any white-light microscope equipped with nanometric Z-stack module.

  11. Improvement of diffraction efficiency of three-dimensional magneto-optic spatial light modulator with magnetophotonic crystal

    SciTech Connect

    Nakamura, K.; Takagi, H. Lim, P. B.; Inoue, M.; Goto, Taichi; Horimai, H.; Yoshikawa, H.; Bove, V. M.

    2016-01-11

    We have developed three-dimensional magneto-optic spatial light modulators (3D-MOSLMs) that use magnetic domains as submicron scale pixels to represent holograms. Our display system uses a submicron-scale magnetic pixel array on an amorphous TbFe film to create a wide viewing angle hologram. However, in previous work the reconstructed images had a low intensity and a low optical contrast; brightness of the reconstructed image was 4.4 × 10{sup −2 }cd/m{sup 2} with 532 nm illumination light at 10.8 mW/cm{sup 2}, while display standard ISO13406 recommends 100 cd/m{sup 2} or more. In this paper, we describe our development of a 3D-MOSLM composed of an artificial magnetic lattice structure of magnetophotonic crystals (MPCs). The MPCs enhance the diffraction efficiency of reconstructed 3D images and reduce the power consumption for controlling the magnetic pixels by a light localization effect. We demonstrate reconstructed 3D images using the MPC and show significant brightness improvement.

  12. Light

    NASA Astrophysics Data System (ADS)

    Vernon, C. G.

    2016-09-01

    Preface; 1. Historical; 2. Waves and wave-motion; 3. The behaviour of ripples; 4. The behaviour of light; 5. Refraction through glass blocks and prisms; 6. The imprinting of curvatures; 7. Simple mathematical treatment; 8. More advanced mathematical treatment; 9. The velocity of light; 10. The spectrum and colour; 11. Geometrical optics; 12. The eye and optical instruments; 13. Sources of light; 14. Interference, diffraction and polarisation; 15. Suggestions for class experiments; Index.

  13. Analysis and suppression of high-order diffractions in liquid-crystal-based spatial light modulator for photonic switch application

    NASA Astrophysics Data System (ADS)

    Nakajima, Mitsumasa; Nemoto, Naru; Yamaguchi, Keita; Kudo, Hiroshi; Yamaguchi, Joji; Suzuki, Kenya; Hashimoto, Toshikazu

    2017-09-01

    Spatial light modulators based on liquid crystal on silicon (LCOS) are widely used for large-scale photonic switches in optical telecom network. For this application, high-order diffractions in LCOS is a critical issue because it causes signal crosstalk. In this paper, we analyze the impact of phase inaccuracy due to the fringing electric field in LCOS on the signal crosstalk in optical switches. We also propose a crosstalk reduction method that is analogous to frequency modulation in signal processing. The method is simple and optimized by only using a few parameters of the applied phase pattern without the need to modify the optics or electronics in use. With the proposed method, the worst crosstalk of a photonic switch was decreased from -16.2 to -31.6 dB.

  14. Time dependent diffraction ring patterns in bromothymol blue dye doped PMMA film under irradiation with continuous wave green laser light

    NASA Astrophysics Data System (ADS)

    Al-Saymari, F. A.; Badran, H. A.; Al-Ahmad, A. Y.; Emshary, C. A.

    2013-11-01

    Diffraction ring patterns are generated in bromothymol blue (BTB) doped poly methyl methacrylate (PMMA) film with the aid of visible light from a solid state laser of Gaussian distribution. Temporal evolution of patterns i.e. the number of rings increases as time elapse is observed. Based on the experimental findings, change in refractive index ( ∆n) effective nonlinear refractive index ( n 2) and variation of refractive index with temperature ( dn/ dT) have been obtained as 0.0025, 1.45 × 10-6 cm2 W-1, 1.69 × 10-5 K-1 respectively. Obtained results suggest the possibility of using BTB doped PMMA in data storage, recording and holography.

  15. Ultrafast dynamic ellipsometry and spectroscopies of laser shocked materials

    SciTech Connect

    Mcgrane, Shawn David; Bolme, Cindy B; Whitley, Von H; Moore, David S

    2010-01-01

    Ultrafast ellipsometry and transient absorption spectroscopies are used to measure material dynamics under extreme conditions of temperature, pressure, and volumetric compression induced by shock wave loading with a chirped, spectrally clipped shock drive pulse.

  16. Coupling the normal incident light into waveguide modes of DBR mirrors via a diffraction grating

    PubMed Central

    Yang, Wenhong; Sun, Shang; Zhang, Chen; Li, Jiankai; Duan, Zonghui; Song, Qinghai; Xiao, Shumin

    2016-01-01

    Here we numerically and experimentally demonstrate the conversion of normally incident light into the guiding modes of distributed Bragg reflector (DBRs) mirror. By fabricating a gold grating onto a 7.5 pairs TiO2/SiO2 DBR mirror, a series of asymmetrical resonances have been formed at the bandgap range of the DBR mirror. The detailed numerical calculations show that these Fano resonances are attributed to the coupling of incident waves into guiding modes of the DBR mirror. Compared with the other resonances, this coupling mechanism can be simply realized and it has also been revealed to be quite robust to the environmental changes, making the conversion between propagating waves and guiding waves to be practically interesting for many applications. PMID:27958336

  17. Beyond crystallography: diffractive imaging using coherent x-ray light sources.

    PubMed

    Miao, Jianwei; Ishikawa, Tetsuya; Robinson, Ian K; Murnane, Margaret M

    2015-05-01

    X-ray crystallography has been central to the development of many fields of science over the past century. It has now matured to a point that as long as good-quality crystals are available, their atomic structure can be routinely determined in three dimensions. However, many samples in physics, chemistry, materials science, nanoscience, geology, and biology are noncrystalline, and thus their three-dimensional structures are not accessible by traditional x-ray crystallography. Overcoming this hurdle has required the development of new coherent imaging methods to harness new coherent x-ray light sources. Here we review the revolutionary advances that are transforming x-ray sources and imaging in the 21st century. Copyright © 2015, American Association for the Advancement of Science.

  18. Coupling the normal incident light into waveguide modes of DBR mirrors via a diffraction grating

    NASA Astrophysics Data System (ADS)

    Yang, Wenhong; Sun, Shang; Zhang, Chen; Li, Jiankai; Duan, Zonghui; Song, Qinghai; Xiao, Shumin

    2016-12-01

    Here we numerically and experimentally demonstrate the conversion of normally incident light into the guiding modes of distributed Bragg reflector (DBRs) mirror. By fabricating a gold grating onto a 7.5 pairs TiO2/SiO2 DBR mirror, a series of asymmetrical resonances have been formed at the bandgap range of the DBR mirror. The detailed numerical calculations show that these Fano resonances are attributed to the coupling of incident waves into guiding modes of the DBR mirror. Compared with the other resonances, this coupling mechanism can be simply realized and it has also been revealed to be quite robust to the environmental changes, making the conversion between propagating waves and guiding waves to be practically interesting for many applications.

  19. Beyond crystallography: Diffractive imaging using coherent x-ray light sources

    SciTech Connect

    Miao, J.; Ishikawa, T.; Robinson, I. K.; Murnane, M. M.

    2015-04-30

    X-ray crystallography has been central to the development of many fields of science over the past century. It has now matured to a point that as long as good-quality crystals are available, their atomic structure can be routinely determined in three dimensions. However, many samples in physics, chemistry, materials science, nanoscience, geology, and biology are noncrystalline, and thus their three-dimensional structures are not accessible by traditional x-ray crystallography. Overcoming this hurdle has required the development of new coherent imaging methods to harness new coherent x-ray light sources. Here we review the revolutionary advances that are transforming x-ray sources and imaging in the 21st century.

  20. Implementation of single-shot ellipsometry on gas gun experiments

    NASA Astrophysics Data System (ADS)

    Grant, Sean; Ao, Tommy; Bernstein, Aaron; Ditmire, Todd; Dolan, Dan; Lin, Jung-Fu; Seagle, Chris; Davis, Jean-Paul

    2017-01-01

    We have built and implemented a time-resolved ellipsometry diagnostic for dynamic material properties experiments at Sandia National Laboratories. This diagnostic measures the complex dielectric value of a sample experiencing dynamic compression, with a time resolution of a few nanoseconds. We show and discuss the dynamic ellipsometry measurements taken from shock loading experiments on a gas gun. This work is relevant to geophysical materials at high pressure-temperature conditions.

  1. Optical study of BST films combining ellipsometry and reflectivity

    NASA Astrophysics Data System (ADS)

    Železný, V.; Chvostová, D.; Pajasová, L.; Jelínek, M.; Kocourek, T.; Daniš, S.; Valvoda, V.

    2009-03-01

    Optical properties of plasma laser-deposited Ba 0.75Sr 0.25TiO 3 (BST) thin films have been investigated using variable angle spectroscopic ellipsometry (VASE) and near-normal spectroscopic reflectivity (NNSR) within a broad spectral range at room temperature. The samples prepared under various deposition conditions and the Si substrate coated with the structure SiO 2/TiO x/Pt were measured. The X-ray diffraction, atomic force microscopy and alpha step measurement were used for characterization of the samples. A special attention was paid to study sample texture. Both sets of experimental data (VASE and NNSR) were fitted simultaneously to obtain the optical constants (e.g. complex refractive index) and thicknesses of the films. For modeling of the experimental data in the range of transparency the Cauchy and Urbach formulas were used. The direct fit procedure and the Cody-Lorentz model were applied around and below absorption edge. In the entire spectral range the reflectivity spectra were analyzed by Kramers-Kronig analysis. The data around the absorption edge were fitted using the single-wavelength method and the absorption edge features were found up about 3.5 eV. The platinum-coated Si substrate data were fitted as a semi-infinite medium using the Drude and Lorentz oscillators model. The structure model for optical characterization of the sample included not only the BST layers and substrate but also the intermix and surface roughness layers to achieve good agreement with experimental data. The substrate structure was modeled by a simple bulk with surface roughness.

  2. Creation of vector beams from a polarization diffraction grating using a programmable liquid crystal spatial light modulator and a q-plate

    NASA Astrophysics Data System (ADS)

    Badham, Katherine Emily

    This thesis presents the ability of complete polarization control of light to create a polarization diffraction grating (PDG). This system has the ability to create diffracted light with each order having a separate high-order polarization state in one location on the optical axis. First, an external Excel program is used to create a grating phase profile from userspecified target diffraction orders. High-order vector beams in this PDG are created using a combination of two devices---a liquid crystal spatial light modulator (LC-SLM) manufactured by Seiko Epson, and a tunable q -plate from Citizen Holdings Co. The transmissive SLM is positioned in an optical setup with a reflective architecture allowing control over both the horizontal and vertical components of the laser beam. The SLM has its LC director oriented vertically only affecting the vertically polarized state, however, the optical setup allows modulation of both vertical and horizontal components by the use of a quarter-wave plate (QWP) and a mirror to rotate the polarizations 90 degrees. Each half of the SLM is encoded with an anisotropic phase-only diffraction grating which are superimposed to create a select number of orders with the desired polarization states and equally distributed intensity. The technique of polarimetry is used to confirm the polarization state of each diffraction order. The q-plate is an inhomogeneous birefringent waveplate which has the ability to convert zero-order vector beams into first-order vector beams. The physical placement of this device into the system converts the orders with zero-order polarization states to first-order polarization states. The light vector patterns of each diffraction order confirm which first-order polarization state of is produced. A specially made PDG sextuplicator is encoded onto the SLM to generate six diffraction orders with separate states of polarization.

  3. Spectroscopic ellipsometry investigations of optical anisotropy in obliquely deposited hafnia thin films

    SciTech Connect

    Tokas, R. B. Jena, Shuvendu; Thakur, S.; Sahoo, N. K.; Haque, S. Maidul; Rao, K. Divakar

    2016-05-23

    In present work, HfO{sub 2} thin films have been deposited at various oblique incidences on Si substrates by electron beam evaporation. These refractory oxide films exhibited anisotropy in refractive index predictably due to special columnar microstructure. Spectroscopic ellipsometry being a powerful tool for optical characterization has been employed to investigate optical anisotropy. It was observed that the film deposited at glancing angle (80°) exhibits the highest optical anisotropy. Further, anisotropy was noticed to decrease with lower values of deposition angles while effective refractive index depicts opposite trend. Variation in refractive index and anisotropy has been explained in light of atomic shadowing during growth of thin films at oblique angles.

  4. Investigation on bandgap, diffraction, interference, and refraction effects of photonic crystal structure in GaN/InGaN LEDs for light extraction.

    PubMed

    Patra, Saroj Kanta; Adhikari, Sonachand; Pal, Suchandan

    2014-06-20

    In this paper, we have made a clear differentiation among bandgap, diffraction, interference, and refraction effects in photonic crystal structures (PhCs). For observing bandgap, diffraction, and refraction effects, PhCs are considered on the top p-GaN surface of light emitting diodes (LEDs), whereas for interference effect, hole type PhCs are considered to be embedded within n-GaN layer of LED. From analysis, it is observed that at a particular lattice periodicity, for which bandgap lies within the wavelength of interest shows a significant light extraction due to inhibition of guided mode. Beyond a certain periodicity, diffraction effect starts dominating and light extraction improves further. The interference effect is observed in embedded photonic crystal LEDs, where depth of etching supports constructive interference of outward light waves. We have also shed light on refraction effects exhibited by the PhCs and whether negative refraction properties of PhCs may be useful in case of LED light extraction.

  5. Interferometric method for phase calibration in liquid crystal spatial light modulators using a self-generated diffraction-grating.

    PubMed

    Fuentes, José Luis Martínez; Fernández, Enrique J; Prieto, Pedro M; Artal, Pablo

    2016-06-27

    An auto-referenced interferometric method for calibrating phase modulation of parallel-aligned liquid crystal (PAL) spatial light modulators (SLM) is described. The method is experimentally straightforward, robust, and requires solely of a collimated beam, with no need of additional optics. This method uses the SLM itself to create a tilted plane wave and a reference wave which mutually interfere. These waves are codified by means of a binary diffraction grating and a uniformly distributed gray level area (piston) into the SLM surface. Phase shift for each gray level addressed to the piston section can then be evaluated. Phase modulation on the SLM can also be retrieved with the proposed method over spatially resolved portions of the surface. Phase information obtained with this novel method is compared to other well established calibration procedures, requiring extra elements and more elaborated optical set-ups. The results show a good agreement with previous methods. The advantages of the new method include high mechanical stability, faster performance, and a significantly easier practical implementation.

  6. Electron diffraction studies of light-induced conformational changes in the Leu-93 → Ala bacteriorhodopsin mutant

    PubMed Central

    Subramaniam, Sriram; Faruqi, A. R.; Oesterhelt, Dieter; Henderson, Richard

    1997-01-01

    We previously have presented evidence for prominent structural changes in helices F and G of bacteriorhodopsin during the photocycle. These changes were determined by carrying out electron diffraction analysis of illuminated two-dimensional crystals of wild-type bacteriorhodopsin or the Asp-96 → Gly mutant that were trapped at a stage in the photocycle after light-driven proton release, but preceding proton uptake from the aqueous medium. Here, we report structural analysis of the long-lived O intermediate observed in the photocycle of the Leu-93 → Ala mutant, which accumulates after the release and uptake of protons, but before the reisomerization of retinal to its initial all-trans state. Projection Fourier difference maps show that upon illumination of the Leu-93 → Ala mutant, significant structural changes occur in the vicinity of helices C, B, and G, and to a lesser extent near helix F. Our results suggest that (i) all four helices that line the proton channel (B, C, F, and G) participate in structural changes during the late stages of the photocycle, and (ii) completion of the photocycle involves significant conformational changes in addition to those that are associated with steps in proton transport. PMID:9050853

  7. Spectroscopic ellipsometry as a sensitive monitor of materials contamination

    NASA Technical Reports Server (NTRS)

    Hale, Jeffrey S.; Hilfiker, James N.; Spady, Blaine; Synowicki, R.; Woollam, John A.

    1995-01-01

    Spectroscopic ellipsometry is demonstrated to be extremely sensitive to contamination layers in the thickness range from 0.1 nm to 10 microns. In the present experiments we deposit either a thin lubricating oil (WD-40) or mineral oil continuously onto Ir, Cu, Al, Au, and V substrates from a bubbler, and monitor its thickness growth from sub-nanometer to tens of nanometers as a function of time. Re-evaporation of contaminant oils is also monitored in real-time by ellipsometry.

  8. Microstructural Changes in MBE Growth of Low-Temperature Gallium Arsenide Observed by in Situ Ellipsometry

    NASA Astrophysics Data System (ADS)

    Eyink, Kurt Gerard

    1995-01-01

    An ellipsometer system has been developed for in-situ monitoring of III-V semiconductor growth using molecular beam epitaxy. Included as part of this work, a software package was developed for the calibration, acquisition, display and modeling of ellipsometry data. This calibration software addresses the arbitrary orientations of the analyzer and polarizer components that are present in the mounting of the ellipsometer on the MBE system. In addition, this package calculated the trajectory followed during the growth of a homogeneous film. The materials used in the modeling are restricted to either an isotropic material or a uniaxial material with the optic axis oriented normal to the surface. External to the real-time software package, a general scheme for the analysis of ellipsometric data was developed using MATLAB. The ellipsometer described above was utilized to reproducibly grow and monitor the growth of low temperature (LT) GaAs films in-situ. In particular the capping of GaAs(001) with As was monitored and a method was developed which could be used to characterize the growth temperature of GaAs in the vicinity of 190^circ C. This method utilizes the temperature for the formation of a thin film of As on GaAs(001). Using this technique to set the growth conditions, LT-GaAs films were grown and monitored in real-time with the ellipsometer and characterized ex-situ with X-ray diffraction (XRD) and transmission electron microscopy (TEM.) The ellipsometry data allowed for the observation of the formation of the epitaxial LT-GaAs film and a subsequent region of changing dielectric properties. These results are correlated with observation in double crystal X-ray diffraction (DXRD) and TEM analysis, showing that the refractive index can be used to indicate the composition of the LT-GaAs films and that the ellipsometer can observe the breakdown in the crystallinity of the LT-GaAs layers.

  9. Photon diffraction

    NASA Astrophysics Data System (ADS)

    Hodge, John

    2009-11-01

    In current light models, a particle-like model of light is inconsistent with diffraction observations. A model of light is proposed wherein photon inferences are combined with the cosmological scalar potential model (SPM). That the photon is a surface with zero surface area in the travel direction is inferred from the Michelson-Morley experiment. That the photons in slits are mathematically treated as a linear antenna array (LAA) is inferred from the comparison of the transmission grating interference pattern and the single slit diffraction pattern. That photons induce a LAA wave into the plenum is inferred from the fractal model. Similarly, the component of the photon (the hod) is treated as a single antenna radiating a potential wave into the plenum. That photons are guided by action on the surface of the hod is inferred from the SPM. The plenum potential waves are a real field (not complex) that forms valleys, consistent with the pilot waves of the Bohm interpretation of quantum mechanics. Therefore, the Afshar experiment result is explained, supports Bohm, and falsifies Copenhagen. The papers may be viewed at http://web.citcom.net/˜scjh/.

  10. The optical characterization of organometallic complex thin films by spectroscopic ellipsometry and photovoltaic diode application

    SciTech Connect

    Özaydın, C.; Güllü, Ö.; Pakma, O.; Ilhan, S.; Akkılıç, K.

    2016-05-15

    Highlights: • Optical properties and thickness of the A novel organometallic complex (OMC) film were investigated by spectroscopic ellipsometry (SE). • Au/OMC/n-Si metal/interlayer/semiconductor (MIS) diode has been fabricated • This paper presents the I–V analysis of Au/OMC/n-Si MIS diode. • Current–voltage and photovoltaic properties of the diode were investigated. - Abstract: In this work, organometallic complex (OMC) films have been deposited onto glass or silicon substrates by spin coating technique and their photovoltaic application potential has been investigated. Optical properties and thickness of the film have been investigated by spectroscopic ellipsometry (SE). Also, transmittance spectrum has been taken by UV/vis spectrophotometer. The optical method has been used to determine the band gap value of the films. Also, Au/OMC/n-Si metal/interlayer/semiconductor (MIS) diode has been fabricated. Current–voltage and photovoltaic properties of the structure were investigated. The ideality factor (n) and barrier height (Φ{sub b}) values of the diode were found to be 2.89 and 0.79 eV, respectively. The device shows photovoltaic behavior with a maximum open-circuit voltage of 396 mV and a short circuit current of 33.8 μA under 300 W light.

  11. Diffraction-Based Optical Switch

    NASA Technical Reports Server (NTRS)

    Sperno, Stevan M. (Inventor); Fuhr, Peter L. (Inventor); Schipper, John F. (Inventor)

    2005-01-01

    Method and system for controllably redirecting a light beam, having a central wavelength lambda, from a first light-receiving site to a second light-receiving site. A diffraction grating is attached to or part of a piezoelectric substrate, which is connected to one or two controllable voltage difference sources. When a substrate voltage difference is changed and the diffraction grating length in each of one or two directions is thereby changed, at least one of the diffraction angle, the diffraction order and the central wavelength is controllably changed. A diffracted light beam component, having a given wavelength, diffraction angle and diffraction order, that is initially received at a first light receiving site (e.g., a detector or optical fiber) is thereby controllably shifted or altered and can be received at a second light receiving site. A polynomially stepped, chirped grating is used in one embodiment. In another embodiment, an incident light beam, having at least one of first and second wavelengths, lambda1 and lambda2, is received and diffracted at a first diffraction grating to provide a first diffracted beam. The first diffracted beam is received and diffracted at a second diffraction grating to produce a second diffracted beam. The second diffracted beam is received at a light-sensitive transducer, having at least first and second spaced apart light detector elements that are positioned so that, when the incident light beam has wavelength lambda1 or lambda2 (lambda1 not equal to lambda2), the second diffracted beam is received at the first element or at the second element, respectively; change in a selected physical parameter at the second grating can also be sensed or measured. A sequence of spaced apart light detector elements can be positioned along a linear or curvilinear segment with equal or unequal spacing.

  12. Fine characterization of ITO layers by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Boher, Pierre; Defranoux, Christophe; Piel, Jean-Philippe; Stehle, Jean-Louis P.; Suzuki, Y.

    1996-08-01

    Indium tin oxide films (ITO) are characterized precisely by spectroscopic ellipsometry which determines not only the thickness of the layers but also the optical indices in a large spectral range. The quality of the ITO films is checked by the transparency of the layers in the visible range 0.4 to 0.6 micrometers . Indeed, target degradation is detected by the occurrence of an absorption band in this region. The electrical conductivity of the layer can also be deduced by the Drude model applied to the absorption in the infrared region. Moreover, spectroscopic ellipsometry can give all these information on all the surface of the panels, checking at the same time the homogeneity and the stability of the deposition process. Different experimental examples will be presented and discussed.

  13. Sensitivity analysis for OMOG and EUV photomasks characterized by UV-NIR spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Heinrich, A.; Dirnstorfer, I.; Bischoff, J.; Meiner, K.; Richter, U.; Mikolajick, T.

    2013-09-01

    We investigated the potentials, applicability and advantages of spectroscopic ellipsometry (SE) for the characterization of high-end photomasks. The SE measurements were done in the ultraviolet-near infrared (UVNIR) wavelength range from 300 nm to 980 nm, at angle of incidences (AOI) between 10 and 70° and with a microspot size of 45 x 10 μm2 (AOI=70°). The measured Ψ and 𝛥 spectra were modeled using the rigorous coupled wave analysis (RCWA) to determine the structural parameters of a periodic array, i.e. the pitch and critical dimension (CD). Two different types of industrial photomasks consisting of line/space structures were evaluated, the reflecting extreme ultraviolet (EUV) and the transmitting opaque MoSi on glass (OMOG) mask. The Ψ and 𝛥 spectra of both masks show characteristic differences, which were related to the Rayleigh singularities and the missing transmission diffraction in the EUV mask. In the second part of the paper, a simulation based sensitivity analysis of the Fourier coefficients α and β is presented, which is used to define the required measurement precision to detect a CD deviation of 1%. This study was done for both mask types to investigate the influence of the stack transmission. It was found that sensitivities to CD variations are comparable for OMOG and EUV masks. For both masks, the highest sensitivities appear close to the Rayleigh singularities and significantly increase at very low AOI. To detect a 1% CD deviation for pitches below 150 nm a measurement precision in the order of 0.01 is required. This measurement precision can be realized with advanced optical hardware. It is concluded that UV-NIR ellipsometry is qualified to characterize photomasks down to the 13 nm technology node in 2020.

  14. 7 Å Resolution in Protein 2-Dimentional-Crystal X-Ray Diffraction at Linac Coherent Light Source

    SciTech Connect

    Pedrini, Bill; Tsai, Ching-Ju; Capitani, Guido; Padeste, Celestino; Hunter, Mark; Zatsepin, Nadia A.; Barty, Anton; Benner, Henry; Boutet, Sebastien; Feld, Geoffrey K.; Hau-Riege, Stefan; Kirian, Rick; Kupitz, Christopher; Messerschmidt, Marc; Ogren, John I.; Pardini, Tommaso; Segelke, Brent; Williams, Garth J.; Spence , John C.; Abela, Rafael; Coleman, Matthew A.; Evans, James E.; Schertler, Gebhard; Frank, Matthias; Li, Xiao-Dan

    2014-06-09

    Membrane proteins arranged as two-dimensional (2D) crystals in the lipid en- vironment provide close-to-physiological structural information, which is essential for understanding the molecular mechanisms of protein function. X-ray diffraction from individual 2D crystals did not represent a suitable investigation tool because of radiation damage. The recent availability of ultrashort pulses from X-ray Free Electron Lasers (X-FELs) has now provided a mean to outrun the damage. Here we report on measurements performed at the LCLS X-FEL on bacteriorhodopsin 2D crystals mounted on a solid support and kept at room temperature. By merg- ing data from about a dozen of single crystal diffraction images, we unambiguously identified the diffraction peaks to a resolution of 7 °A, thus improving the observable resolution with respect to that achievable from a single pattern alone. This indicates that a larger dataset will allow for reliable quantification of peak intensities, and in turn a corresponding increase of resolution. The presented results pave the way to further X-FEL studies on 2D crystals, which may include pump-probe experiments at subpicosecond time resolution.

  15. New insights into colloidal gold flakes: structural investigation, micro-ellipsometry and thinning procedure towards ultrathin monocrystalline layers

    NASA Astrophysics Data System (ADS)

    Hoffmann, B.; Bashouti, M. Y.; Feichtner, T.; Mačković, M.; Dieker, C.; Salaheldin, A. M.; Richter, P.; Gordan, O. D.; Zahn, D. R. T.; Spiecker, E.; Christiansen, S.

    2016-02-01

    High-quality fabrication of plasmonic devices often relies on wet-chemically grown ultraflat, presumably single-crystalline gold flakes due to their superior materials properties. However, important details about their intrinsic structure and their optical properties are not well understood yet. In this study, we present a synthesis routine for large flakes with diameters of up to 70 μm and an in-depth investigation of their structural and optical properties. The flakes are precisely analyzed by transmission electron microscopy, electron backscatter diffraction and micro-ellipsometry. We found new evidence for the existence of twins extending parallel to the Au flake {111} surfaces which have been found to not interfere with the presented nanopatterning. Micro-Ellipsometry was carried out to determine the complex dielectric function and to compare it to previous measurements of bulk single crystalline gold. Finally, we used focused ion beam milling to prepare smooth crystalline layers and high-quality nanostructures with desired thickness down to 10 nm to demonstrate the outstanding properties of the flakes. Our findings support the plasmonics and nano optics community with a better understanding of this material which is ideally suited for superior plasmonic nanostructures.High-quality fabrication of plasmonic devices often relies on wet-chemically grown ultraflat, presumably single-crystalline gold flakes due to their superior materials properties. However, important details about their intrinsic structure and their optical properties are not well understood yet. In this study, we present a synthesis routine for large flakes with diameters of up to 70 μm and an in-depth investigation of their structural and optical properties. The flakes are precisely analyzed by transmission electron microscopy, electron backscatter diffraction and micro-ellipsometry. We found new evidence for the existence of twins extending parallel to the Au flake {111} surfaces which have

  16. Correlation between intensity fluctuations of light generated by scattering of Young’s diffractive electromagnetic waves by a quasi-homogeneous, anisotropic medium

    NASA Astrophysics Data System (ADS)

    Li, Jia; Chen, Feinan

    2016-11-01

    Based on the first-order Born approximation, formulas are derived for the correlation between intensity fluctuations (CIF) of light generated by a Young’s diffractive electromagnetic wave scattered by a spatially quasi-homogeneous (QH), anisotropic medium. It is shown that the CIF of the scattered field can be written as the summation of the Fourier transforms of the strengths and normalized correlation coefficients (NCCs) of the scattering potentials. The differences between our results and those obtained in the previous literature are discussed. Our results might be important in investigating the high-order intensity correlation of an electromagnetic wave scattered from a 3D anisotropic object.

  17. Modeling of the diffraction efficiency and polarization sensitivity for a liquid crystal 2D spatial light modulator for reconfigurable beam steering.

    PubMed

    James, Richard; Fernández, F Aníbal; Day, Sally E; Komarcević, Milos; Crossland, William A

    2007-08-01

    A nematic liquid crystal spatial light modulator used as a phase-modulating device and operating in the reflective mode is analyzed using three-dimensional modeling. Two configurations, which differ in their electrode placement relative to a fixed quarter-wave plate, are considered across a range of steering directions, with the grating conformal and in some cases oblique to the pixel grid. For each steering direction the sensitivity of the diffraction orders to the polarization state of the incident wavefront is studied. Optimal alignment of the liquid crystal is suggested to reduce this sensitivity.

  18. 3.5 W of diffraction-limited green light at 515 nm from SHG of a single-frequency tapered diode laser

    NASA Astrophysics Data System (ADS)

    Bjarlin Jensen, Ole; Hansen, Anders Kragh; Müller, André; Sumpf, Bernd; Petersen, Paul Michael; Andersen, Peter E.

    2017-02-01

    Multi-Watt efficient compact green laser sources are required for a number of applications e.g. within biophotonics, laser pumping and laser displays. We present generation of 3.5 W of diffraction-limited green light at 515 nm by second harmonic generation (SHG) of a tapered diode laser, itself yielding more than 9 W at 1030 nm. SHG is performed in single pass through a cascade of two nonlinear crystals with re-focusing and dispersion compensating optics between the two nonlinear crystals. The laser is single-frequency and the output power is stabilized to better than +/-0.4%.

  19. LASER APPLICATIONS AND OTHER ASPECTS OF QUANTUM ELECTRONICS Measurement of angular parameters of divergent optical radiation by light diffraction on sound

    NASA Astrophysics Data System (ADS)

    Kotov, V. M.; Averin, S. V.; Shkerdin, G. N.

    2010-12-01

    A method is proposed to measure the scattering angle of optical radiation, the method employing two Bragg diffraction processes in which divergent optical radiation propagates close to the optical axis of a uniaxial crystal, while the acoustic wave — orthogonally to this axis. The method does not require additional angular tuning of the acousto-optic cell. We suggest using a mask to measure the light divergence that is larger than the angle of Bragg scattering. The method can be used to measure the size of the polished glass plate inhomogeneities.

  20. Mueller-matrix ellipsometry studies of optically active structures in scarab beetles

    NASA Astrophysics Data System (ADS)

    Järrendahl, K.; Landin, J.; Arwin, H.

    2010-06-01

    The complexity of multilayers, photonic crystals, metamaterials and other artificial materials has promoted the use of spectroscopic, variable angle, generalized and Mueller-matrix ellipsometry. Naturally occurring structures may show even higher complexity than artificial structures but with a more narrow range of constituent materials. Fascinating reflection properties result from intricate photonic structures in, for instance, the wing scales and cuticles of insects. Currently there is a large interest to explore such functional supramolecular architectures for exploitation in nanotechnology. In this study, Mueller-matrix spectroscopic ellipsometry is applied in the spectral range of 250 to 1000 nm to investigate optical response and structures of the cuticle of Scarab beetles of the Cetoniinae subfamily. The cuticle of Cetonia aurata (the rose chafer, la cétoine dorée) is green with a metallic appearance and reflects left-handed circular/elliptically polarized light. It has been suggested that the polarization of this metallic gloss is caused by a helical structure in the chitinous cuticle. We find that the polarization effect is limited to the narrow spectral range 470-550 nm whereas for shorter or longer wavelengths the reflection properties are similar to those from a near-dielectric material. Model calculations and parameterization of the nanostructure employing a heliocoidal structure are discussed. As a comparison the polarization effects from light reflected from two other beetles will be presented. Coptomia laevis has a similar appearance as Cetonia aurata but has very different polarization properties. The golden Plusiotis argentiola has very interesting properties showing both left and right-handed polarization depending on incidence angle and wavelength.

  1. Diffraction-based optical correlator

    NASA Technical Reports Server (NTRS)

    Spremo, Stevan M. (Inventor); Fuhr, Peter L. (Inventor); Schipper, John F. (Inventor)

    2005-01-01

    Method and system for wavelength-based processing of a light beam. A light beam, produced at a chemical or physical reaction site and having at least first and second wavelengths, ?1 and ?2, is received and diffracted at a first diffraction grating to provide first and second diffracted beams, which are received and analyzed in terms of wavelength and/or time at two spaced apart light detectors. In a second embodiment, light from first and second sources is diffracted and compared in terms of wavelength and/or time to determine if the two beams arise from the same source. In a third embodiment, a light beam is split and diffracted and passed through first and second environments to study differential effects. In a fourth embodiment, diffracted light beam components, having first and second wavelengths, are received sequentially at a reaction site to determine whether a specified reaction is promoted, based on order of receipt of the beams. In a fifth embodiment, a cylindrically shaped diffraction grating (uniform or chirped) is rotated and translated to provide a sequence of diffracted beams with different wavelengths. In a sixth embodiment, incident light, representing one or more symbols, is successively diffracted from first and second diffraction gratings and is received at different light detectors, depending upon the wavelengths present in the incident light.

  2. Reflective diffraction grating

    DOEpatents

    Lamartine, Bruce C.

    2003-06-24

    Reflective diffraction grating. A focused ion beam (FIB) micromilling apparatus is used to store color images in a durable medium by milling away portions of the surface of the medium to produce a reflective diffraction grating with blazed pits. The images are retrieved by exposing the surface of the grating to polychromatic light from a particular incident bearing and observing the light reflected by the surface from specified reception bearing.

  3. Comparison between ray-tracing and physical optics for the computation of light absorption in capillaries--the influence of diffraction and interference.

    PubMed

    Qin, Yuan; Michalowski, Andreas; Weber, Rudolf; Yang, Sen; Graf, Thomas; Ni, Xiaowu

    2012-11-19

    Ray-tracing is the commonly used technique to calculate the absorption of light in laser deep-penetration welding or drilling. Since new lasers with high brilliance enable small capillaries with high aspect ratios, diffraction might become important. To examine the applicability of the ray-tracing method, we studied the total absorptance and the absorbed intensity of polarized beams in several capillary geometries. The ray-tracing results are compared with more sophisticated simulations based on physical optics. The comparison shows that the simple ray-tracing is applicable to calculate the total absorptance in triangular grooves and in conical capillaries but not in rectangular grooves. To calculate the distribution of the absorbed intensity ray-tracing fails due to the neglected interference, diffraction, and the effects of beam propagation in the capillaries with sub-wavelength diameter. If diffraction is avoided e.g. with beams smaller than the entrance pupil of the capillary or with very shallow capillaries, the distribution of the absorbed intensity calculated by ray-tracing corresponds to the local average of the interference pattern found by physical optics.

  4. Evaluation of the SEI using a multilayer spectroscopic ellipsometry model

    SciTech Connect

    Eric J. Dufek

    2014-08-01

    A multilayer spectroscopic ellipsometry (SE) model has been developed to characterize SEI formation. The model, which consists of two Cauchy layers, is constructed with an inner layer meant to model primarily inorganic compounds adjacent to an electrode and an outer layer which mirrors polymeric, organic constituents on the exterior of the SEI. Comparison of 1:1 EC:EMC and 1:4 EC:EMC with 1.0 M LiPF6 shows distinct differences in the two modeled layers. The data suggest that the thickness of both layers change over a wide potential range. These changes have been linked with other reports on the growth of the SEI.

  5. Evaluation of the SEI using a multilayer spectroscopic ellipsometry model

    DOE PAGES

    Dufek, Eric J.

    2014-08-28

    A multilayer spectroscopic ellipsometry (SE) model has been developed to characterize SEI formation. The model, which consists of two Cauchy layers, is constructed with an inner layer meant to model primarily inorganic compounds adjacent to an electrode and an outer layer which mirrors polymeric, organic constituents on the exterior of the SEI. Comparison of 1:1 EC:EMC and 1:4 EC:EMC with 1.0 M LiPF₆ shows distinct differences in the two modeled layers. The data suggest that the thickness of both layers change over a wide potential range. These changes have been linked with other reports on the growth of the SEI.

  6. Silicon based affinity biochips viewed with imaging ellipsometry

    NASA Astrophysics Data System (ADS)

    van Noort, Danny; Rumberg, Jens; Jager, Edwin W. H.; Mandenius, Carl-Fredrik

    2000-06-01

    In this paper we report on the fabrication of an affinity biochip with a matrix of 900 targets for detection with imaging ellipsometry. Two methods of fabrication of chips are shown: one based on wet etching of a silicon surface and the other on the preparation of so-called tension wells on the silicon surface. The dispensing of reagents and ligands was performed using a pipetting robot equipped with a micro-capillary, a syringe pump and micro-stepping motors. Measurements were performed on the chips in real time with carbohydrate model substances selected for six common lectins. Affinity binding was shown for three of the tested model substances.

  7. Temperature-dependent spectral generalized magneto-optical ellipsometry

    NASA Astrophysics Data System (ADS)

    Neuber, G.; Rauer, R.; Kunze, J.; Korn, T.; Pels, C.; Meier, G.; Merkt, U.; Bäckström, J.; Rübhausen, M.

    2003-12-01

    We present a setup for temperature-dependent spectral generalized magneto-optical ellipsometry (SGME). This technique gives access to the electronic as well as the magnetic properties of ferromagnetic materials within one single magneto-optical measurement. It also allows the determination of the orientation of the magnetization. We show spectra of the real and the imaginary part of the refractive index N as well as the magneto-optical coupling parameter Q of permalloy and iron films for in-plane magnetization. Our findings demonstrate the relevance of SGME for the understanding of the interplay between electronic and magnetic properties of ferromagnetics.

  8. Implementation of Single-Shot Ellipsometry on Gas Gun Experiments

    NASA Astrophysics Data System (ADS)

    Grant, Sean; Ao, Tommy; Bernstein, Aaron; Davis, Jean-Paul; Ditmire, Todd; Dolan, Daniel; Lin, Jung-Fu; Seagle, Christopher

    2015-06-01

    We have built and implemented a time-resolved ellipsometry diagnostic for dynamic testing at Sandia National Laboratories. This diagnostic measures refractive index of a sample under dynamic conditions with a time resolution of a few nanoseconds. We show and discuss results from our first dynamic experiments on a gas gun. Future work will study geophysical materials under relevant pressure-temperature conditions. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND2015-0376 A.

  9. Antifreeze glycopeptide adsorption on single crystal ice surfaces using ellipsometry

    PubMed Central

    Wilson, P. W.; Beaglehole, D.; DeVries, A. L.

    1993-01-01

    Antarctic fishes synthesise antifreeze proteins which can effectively inhibit the growth of ice crystals. The mechanism relies on adsorption of these proteins to the ice surface. Ellipsometry has been used to quantify glycopeptide antifreeze adsorption to the basal and prism faces of single ice crystals. The rate of accumulation was determined as a function of time and at concentrations between 0.0005 and 1.2 mg/ml. Estimates of packing density at saturation coverage have been made for the basal and prism faces. PMID:19431902

  10. Annotated bibliography of ellipsometry and optical properties of solids

    NASA Astrophysics Data System (ADS)

    Christensen, T. M.

    1985-05-01

    This bibliography is a partial listing of articles on various aspects of ellipsometry and the optical properties of solids. Additional references can be found in the review articles listed in the first section. The comments about the articles represent the author's particular interest in the article and are by no means intended as complete summaries or even statements of the author's key point in the article. The lack of comments on many of the articles represents the author's inconsistent note-taking or the completeness of the author's title in describing the article. The papers are divided into 10 topical sections and are alphabetized within each section.

  11. Ultrafast dynamic ellipsometry and spectroscopy of laser shocked materials

    SciTech Connect

    Bolme, Cynthia A; Mc Grane, Shawn D; Dang, Nhan C; Whitley, Von H; Moore, David S.

    2011-01-20

    Ultrafast dynamic ellipsometry is used to measure the material motion and changes in the optical refractive index of laser shock compressed materials. This diagnostic has shown us that the ultrafast laser driven shocks are the same as shocks on longer timescales and larger length scales. We have added spectroscopic diagnostics of infrared absorption, ultra-violet - visible transient absorption, and femtosecond stimulated Raman scattering to begin probing the initiation chemistry that occurs in shock reactive materials. We have also used the femtosecond stimulated Raman scattering to measure the vibrational temperature of materials using the Stokes gain to anti-Stokes loss ratio.

  12. Transmission and reflection ellipsometry studies of electrochromic materials and devices

    SciTech Connect

    Bader, G.; Ashrit, P.V.; Truong, V.V.

    1995-12-31

    Ellipsometric studies are generally carried out in reflection mode rather than in transmission mode, requiring invariably opaque substrates or substrates in which the back reflection is minimized or suppressed by different methods. In the present work, the authors have used a transmission and reflection photo-ellipsometry method to study electrochromic materials and their multilayer systems deposited on thick substrates. The role of the substrate is examined carefully and the contributions from multiple reflections in the substrate are taken into account in the theoretical treatment. This procedure not only allows the study of thin films deposited on quasi-transparent substrates but carried out in conjunction with reflection measurements improves greatly the accuracy in the determination of the optical constants. Optical measurements have been carried out on an automatic reflection-transmission spectrophoto-ellipsometer. Solid state ionics materials used in electrochromic systems such as indium-tin oxide, tungsten oxide and their multilayer structures deposited on glass substrates are used as examples. A software based on the above theory, OPTIKAN, has been developed to model and analyze such systems. It is demonstrated that the photo-ellipsometry method proposed is especially suited to analyze in a non-destructive way electrochromic materials and transmitting devices.

  13. Spectral ellipsometry studying of iron's optical and electronic properties

    NASA Astrophysics Data System (ADS)

    Chernukha, Yevheniia; Stashchuk, Vasyl S.; Polianska, Olena; Oshtuk, Olexsandr

    2014-05-01

    Fe's optical and electronic properties were investigated at room temperature in different structural states. The sample's surface was explored in wide spectral range λ = 0,23-17,0 μm (E = 4,96 - 0,07 еV ) by the Beatty's spectral ellipsometry method. While an experiment was carried out ellipsometry parameters Δ and ψ were measure near the principal angle of incidence. The refraction index R , permittivity Ɛ and optical conductivity σ( hν ) , that is proportional to the interband density of electronic states, were calculated using these parameters. Fe's optical conductivities in liquid, amorphous and crystalline states were compared in this work. The optical conductivity was calculated using the published data of the iron's density of electronic states in crystalline, amorphous and liquid states for the comparison of the experimental and theoretical results. It is shown that, at structural transformations "amorphous, liquid state- crystalline state", the optical properties of metallic iron are determined, in the first turn, by the nearest neighborhood, and the electronic structure is not subjected to significant modifications.

  14. New insights into colloidal gold flakes: structural investigation, micro-ellipsometry and thinning procedure towards ultrathin monocrystalline layers.

    PubMed

    Hoffmann, B; Bashouti, M Y; Feichtner, T; Mačković, M; Dieker, C; Salaheldin, A M; Richter, P; Gordan, O D; Zahn, D R T; Spiecker, E; Christiansen, S

    2016-02-28

    High-quality fabrication of plasmonic devices often relies on wet-chemically grown ultraflat, presumably single-crystalline gold flakes due to their superior materials properties. However, important details about their intrinsic structure and their optical properties are not well understood yet. In this study, we present a synthesis routine for large flakes with diameters of up to 70 μm and an in-depth investigation of their structural and optical properties. The flakes are precisely analyzed by transmission electron microscopy, electron backscatter diffraction and micro-ellipsometry. We found new evidence for the existence of twins extending parallel to the Au flake {111} surfaces which have been found to not interfere with the presented nanopatterning. Micro-Ellipsometry was carried out to determine the complex dielectric function and to compare it to previous measurements of bulk single crystalline gold. Finally, we used focused ion beam milling to prepare smooth crystalline layers and high-quality nanostructures with desired thickness down to 10 nm to demonstrate the outstanding properties of the flakes. Our findings support the plasmonics and nano optics community with a better understanding of this material which is ideally suited for superior plasmonic nanostructures.

  15. Study of biological reaction in cancer cell with spectroscopic imaging ellipsometry

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Da; Hsu, Hao Yun; Khaleel, Mai Ibrahim; Chang, Yia-Chung; Wu, Chien-Hsun; Wu, Han-Chung

    2016-09-01

    We present experimental studies of live cancer cells via microscopic imaging ellipsometry (MIE). The Rotating Compensator Ellipsometry (RCE) is used for our measurements. Ellipsometry spectra with signals integrated over a 20μm×20μm area in visible range (450nm to 750nm) are obtained with the Optrel MULTISKOP system for both specular reflection and off-specular scattering. The microscopic ellipsometry (ME) images at a few fixed wavelengths within the same range were also analyzed. Dielectric constants for glass slide, culture fluid, and glass cover plate were firstly characterized by spectroscopic ellipsometry measurements, which can be used in the simulation for MIE measurements of cancer cells embedded in the culture fluid and sandwiched between a glass slide and cover plate. The measured ME spectra and images of cancer cells before and after medicine injection are measured and analyzed.

  16. Cryogenic coherent X-ray diffraction imaging of biological samples at SACLA: a correlative approach with cryo-electron and light microscopy.

    PubMed

    Takayama, Yuki; Yonekura, Koji

    2016-03-01

    Coherent X-ray diffraction imaging at cryogenic temperature (cryo-CXDI) allows the analysis of internal structures of unstained, non-crystalline, whole biological samples in micrometre to sub-micrometre dimensions. Targets include cells and cell organelles. This approach involves preparing frozen-hydrated samples under controlled humidity, transferring the samples to a cryo-stage inside a vacuum chamber of a diffractometer, and then exposing the samples to coherent X-rays. Since 2012, cryo-coherent diffraction imaging (CDI) experiments have been carried out with the X-ray free-electron laser (XFEL) at the SPring-8 Ångstrom Compact free-electron LAser (SACLA) facility in Japan. Complementary use of cryo-electron microscopy and/or light microscopy is highly beneficial for both pre-checking samples and studying the integrity or nature of the sample. This article reports the authors' experience in cryo-XFEL-CDI of biological cells and organelles at SACLA, and describes an attempt towards reliable and higher-resolution reconstructions, including signal enhancement with strong scatterers and Patterson-search phasing.

  17. Efficient concept for generation of diffraction-limited green light by sum-frequency generation of spectrally combined tapered diode lasers.

    PubMed

    Müller, André; Jensen, Ole Bjarlin; Hasler, Karl-Heinz; Sumpf, Bernd; Erbert, Götz; Andersen, Peter E; Petersen, Paul Michael

    2012-09-15

    In order to increase the power of visible diode laser systems in an efficient manner, we propose spectral beam combining with subsequent sum-frequency generation. We show that this approach, in comparison with second harmonic generation of single emitters, can enhance the available power significantly. By combining two distributed Bragg reflector tapered diode lasers we achieve a 2.5-3.2 fold increase in power and a maximum of 3.9 W of diffraction-limited green light. At this power level, green diode laser systems have a high application potential, e.g., within the biomedical field. Our concept can be expanded combining multiple diode lasers to increase the power even further.

  18. Characterization of air-coupled ultrasound transducers in the frequency range 40 kHz-2 mHz using light diffraction tomography.

    PubMed

    Almqvist, M; Holm, A; Persson, H W; Lindström, K

    2000-01-01

    The aim of this work was to show the applicability of light diffraction tomography on airborne ultrasound in the frequency range 40 kHz-2 MHz. Seven different air-coupled transducers were measured to show the method's performance regarding linearity, absolute pressure measurements, phase measurements, frequency response, S/N ratio and spatial resolution. A calibrated microphone and the pulse-echo method were used to evaluate the results. The absolute measurements agreed within the calibrated microphone's uncertainty range. Pulse waveforms and corresponding FFT diagrams show the method's higher bandwidth compared with the microphone. Further, the method offers non-perturbing measurements with high spatial resolution, which was especially advantageous for measurements close to the transducer surfaces. The S/N ratio was higher than or in the same range as that of the two comparison methods.

  19. Characterization of SiGe/Ge heterostructures and graded layers using variable angle spectroscopic ellipsometry

    NASA Technical Reports Server (NTRS)

    Croke, E. T.; Wang, K. L.; Heyd, A. R.; Alterovitz, S. A.; Lee, C. H.

    1996-01-01

    Variable angle spectroscopic ellipsometry (VASE) has been used to characterize Si(x)Ge(1-x)/Ge superlattices (SLs) grown on Ge substrates and thick Si(x)Ge(1-x)/Ge heterostructures grown on Si substrates. Our VASE analysis yielded the thicknesses and alloy compositions of all layers within the optical penetration depth of the surface. In addition, strain effects were observed in the VASE results for layers under both compressive and tensile strain. Results for the SL structures were found to be in close agreement with high resolution x-ray diffraction measurements made on the same samples. The VASE analysis has been upgraded to characterize linearly graded Si(x)Ge(1-x) buffer layers. The algorithm has been used to determine the total thickness of the buffer layer along with the start and end alloy composition by breaking the total thickness into many (typically more than 20) equal layers. Our ellipsometric results for 1 (mu)m buffer layers graded in the ranges 0.7 less than or = x less than or = 1.0, and 0.5 less than or = x less than or = 1.0 are presented, and compare favorably with the nominal values.

  20. Characterization of High Ge Content SiGe Heterostructures and Graded Alloy Layers Using Spectroscopic Ellipsometry

    NASA Technical Reports Server (NTRS)

    Heyd, A. R.; Alterovitz, S. A.; Croke, E. T.

    1995-01-01

    Si(x)Ge(1-x)heterostructures on Si substrates have been widely studied due to the maturity of Si technology. However, work on Si(x)Ge)1-x) heterostructures on Ge substrates has not received much attention. A Si(x)Ge(1-x) layer on a Si substrate is under compressive strain while Si(x)Ge(1-x) on Ge is under tensile strain; thus the critical points will behave differently. In order to accurately characterize high Ge content Si(x)Ge(1-x) layers the energy shift algorithm used to calculate alloy compositions, has been modified. These results have been used along with variable angle spectroscopic ellipsometry (VASE) measurements to characterize Si(x)Ge(1-x)/Ge superlattices grown on Ge substrates. The results agree closely with high resolution x-ray diffraction measurements made on the same samples. The modified energy shift algorithm also allows the VASE analysis to be upgraded in order to characterize linearly graded layers. In this work VASE has been used to characterize graded Si(x)Ge(1-x) layers in terms of the total thickness, and the start and end alloy composition. Results are presented for a 1 micrometer Si(x)Ge(1-x) layer linearly graded in the range 0.5 less than or equal to x less than or equal to 1.0.

  1. Visual acuity and patient satisfaction at varied distances and lighting conditions after implantation of an aspheric diffractive multifocal one-piece intraocular lens

    PubMed Central

    Chang, Daniel H

    2016-01-01

    Purpose The aim of the study is to evaluate the visual acuity and patient satisfaction at varied distances under photopic and mesopic lighting conditions in patients bilaterally implanted with aspheric diffractive multifocal one-piece intraocular lenses. Methods In this retrospective–prospective study, 16 patients with a mean age of 66.2±9.2 years (range: 50–81 years) who had undergone bilateral phacoemulsification surgery with implantation of a Tecnis multifocal one-piece intraocular lens (ZMB00) were evaluated. Monocular and binocular uncorrected and distance-corrected visual acuities were measured at distance (20 ft), intermediate (70–80 cm), and near (35–40 cm) under photopic (85 cd/m2) and mesopic (3 cd/m2) lighting conditions and were compared using the paired t-test. All patients also completed a subjective questionnaire. Results At a mean follow-up of 9.5±3.9 months, distance, near, and intermediate visual acuity improved significantly from preoperative acuity. Under photopic and mesopic conditions, 93.8% and 62.5% of patients, respectively, had binocular uncorrected intermediate visual acuity of 20/40 or better, and 62.5% and 31.3% of patients had binocular uncorrected near visual acuity of 20/20 or better. All patients were satisfied with their overall vision without using glasses and/or contact lenses when compared with before surgery. A total of 87.5% of patients reported no glare and 68.8% of patients reported no halos around lights at night. Conclusion Tecnis multifocal one-piece intraocular lenses provide good distance, intermediate, and near visual acuity under photopic as well as mesopic lighting conditions. High levels of spectacle independence with low levels of photic phenomenon were achieved, resulting in excellent patient satisfaction. PMID:27536061

  2. Nucleation and growth of MgO atomic layer deposition: A real-time spectroscopic ellipsometry study

    SciTech Connect

    Wang, Han; Fu, Kan

    2013-11-15

    The atomic layer deposition (ALD) of MgO thin films from bis(cyclopentadienyl) magnesium and H{sub 2}O was studied using in-situ real-time spectroscopic ellipsometry (SE), ex-situ x-ray photoelectron spectroscopy, and grazing-incidence x-ray diffraction. It is found that the initial growth is not linear during the first ten cycles, and magnesium silicate forms spontaneously on the SiO{sub 2}/Si substrates at 250 °C. Submonolayer sensitivity of SE is demonstrated by the analysis of each half-cycle and self-limiting adsorption, revealing characteristic features of hetero- and homo-MgO ALD processes.

  3. Anomalous diffraction approximation limits

    NASA Astrophysics Data System (ADS)

    Videen, Gorden; Chýlek, Petr

    It has been reported in a recent article [Liu, C., Jonas, P.R., Saunders, C.P.R., 1996. Accuracy of the anomalous diffraction approximation to light scattering by column-like ice crystals. Atmos. Res., 41, pp. 63-69] that the anomalous diffraction approximation (ADA) accuracy does not depend on particle refractive index, but instead is dependent on the particle size parameter. Since this is at odds with previous research, we thought these results warranted further discussion.

  4. Development of ultra-broadband terahertz time domain ellipsometry

    NASA Astrophysics Data System (ADS)

    Yamashita, Masatsugu; Otani, Chiko

    2015-08-01

    We developed a reflection type ultra-broad band terahertz time-domain spectroscopic ellipsometry covering the frequency range from 0.5 to 30 THz. The system utilizes two nonlinear optical crystals of GaP and GaSe as terahertz and mid-infrared sources, respectively, and employs a detector based on a photoconductive antenna switch using a low temperature grown GaAs (LT-GaAs) epitaxial layer transferred on Si substrate. By switching the emitter, the measurable frequency range can be easily changed from the 0.5-7.8 THz range to the 7.8-30 THz range without additional optical alignment. We measured the dielectric function of a p-type InAs wafer and the complex optical conductivity of an indium tin oxide (ITO) thin film. The obtained carrier density and the mobility of the ITO thin film show good agreement with that obtained by the Hall

  5. Measuring liquid crystal anchoring energy strength by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Marino, A.; Tkachenko, V.; Santamato, E.; Bennis, N.; Quintana, X.; Otón, J. M.; Abbate, G.

    2010-04-01

    We describe an experimental procedure for accurate measurement of anchoring energy strength of liquid crystal cells. This technique is based on the possibility of gathering a large amount of very precise data about the linear optical response of the cell in different experimental conditions, using spectroscopic ellipsometry. Then, a careful data analysis exploiting data inversion method, supplemented by simulations from the elastic theory, is able to provide the searched information. The technique has been applied to vertical aligned nematic cells, chosen for its widespread use in the present display market. The results obtained in this particular case together with a thorough comparison with existing alternative techniques, suggest that our technique can be an optimum candidate for the industrial implementation of such measurement. A particular example is fully worked out, giving a result with a precision of 1.5% and an accuracy of 10%.

  6. Simultaneous characterization of detector and source imperfections in infrared ellipsometry.

    PubMed

    Wormeester, Herbert; Kole, Pepijn R; Poelsema, Bene

    2009-05-20

    Optical components required for infrared (IR) ellipsometry have distinctly worse characteristics compared to those available for the visible spectrum. The calibration of the optical components used is therefore essential for obtaining reliable results. Here a powerful method is outlined to calibrate simultaneously the polarization characteristics of a source and detector through the synchronous rotation of two polarizers. The performance of this method is to a large degree independent of the quality of (commercially available) polarizers. This renders this method robust and highly suitable for the IR range. Moreover, it is also inherently insensitive toward a nonlinear response of the detector. This enables us to use this method as the first step in the quantification of component imperfections.

  7. Thickness measurement of JFTOT tube deposits by ellipsometry

    SciTech Connect

    Baker, C.; David, P.; Taylor, S.E.; Woodward, A.J.

    1995-04-01

    Thickness measurement of Jet Fuel Thermal Oxidation Test (JFTOT) tube deposits has long been a desirable goal to characterize better the thermal stability of jet fuels. The current visual rating method used for specification purposes suffers from the drawback of operator subjectivity and provides little information on the thickness and volume of deposits, parameters which are far more meaningful for characterizing fuels for users and suppliers. Ellipsometry has been identified as a suitable technique for measuring the thickness of JFTOT tubes. Such a system would be robust and non-destructive; cover the important thickness range with regard to visual ratings; provide quick and easy absolute measurement of thickness; enable single spot and profiling measurements; and there would be no restriction on minimum deposit thickness.

  8. Adsorption of water on porous Vycor glass studied by ellipsometry.

    PubMed

    Alvarez-Herrero, A; Heredero, R L; Bernabeu, E; Levy, D

    2001-02-01

    The variation of the optical properties of porous Vycor glass (Corning, Model 7930) under different relative-humidity conditions was studied. The adsorption of water into the glass pores was investigated with spectroscopic ellipsometry. The change of the refractive index was Deltan approximately 0.04 between 5% and 90% relative humidity. A linear relation between the ellipsometer parameter tan Psi, the amount of water adsorbed in the glass pores, and information about the pore-size distributions was established. The results are in accord with the values obtained from N2 isotherms, transmission electron microscope micrographs, and the manufacturer's specifications (radius of approximately 20 A). The possibility of using this material as a transducer for implementation in a fiber-optic sensor to measure humidity was evaluated.

  9. Measurement of InAsSb bandgap energy and InAs/InAsSb band edge positions using spectroscopic ellipsometry and photoluminescence spectroscopy

    SciTech Connect

    Webster, P. T.; Riordan, N. A.; Liu, S.; Zhang, Y.-H.; Johnson, S. R.; Steenbergen, E. H.

    2015-12-28

    The structural and optical properties of lattice-matched InAs{sub 0.911}Sb{sub 0.089} bulk layers and strain-balanced InAs/InAs{sub 1−x}Sb{sub x} (x ∼ 0.1–0.4) superlattices grown on (100)-oriented GaSb substrates by molecular beam epitaxy are examined using X-ray diffraction, spectroscopic ellipsometry, and temperature dependent photoluminescence spectroscopy. The photoluminescence and ellipsometry measurements determine the ground state bandgap energy and the X-ray diffraction measurements determine the layer thickness and mole fraction of the structures studied. Detailed modeling of the X-ray diffraction data is employed to quantify unintentional incorporation of approximately 1% Sb into the InAs layers of the superlattices. A Kronig-Penney model of the superlattice miniband structure is used to analyze the valence band offset between InAs and InAsSb, and hence the InAsSb band edge positions at each mole fraction. The resulting composition dependence of the bandgap energy and band edge positions of InAsSb are described using the bandgap bowing model; the respective low and room temperature bowing parameters for bulk InAsSb are 938 and 750 meV for the bandgap, 558 and 383 meV for the conduction band, and −380 and −367 meV for the valence band.

  10. Light funneling from a photonic crystal laser cavity to a nano-antenna: overcoming the diffraction limit in optical energy transfer down to the nanoscale.

    PubMed

    Mivelle, Mathieu; Viktorovitch, Pierre; Baida, Fadi I; El Eter, Ali; Xie, Zhihua; Vo, Than-Phong; Atie, Elie; Burr, Geoffrey W; Nedeljkovic, Dusan; Rauch, Jean-Yves; Callard, Ségolène; Grosjean, Thierry

    2014-06-16

    We show that the near-field coupling between a photonic crystal microlaser and a nano-antenna can enable hybrid photonic systems that are both physically compact (free from bulky optics) and efficient at transferring optical energy into the nano-antenna. Up to 19% of the laser power from a micron-scale photonic crystal laser cavity is experimentally transferred to a bowtie aperture nano-antenna (BNA) whose area is 400-fold smaller than the overall emission area of the microlaser. Instead of a direct deposition of the nano-antenna onto the photonic crystal, it is fabricated at the apex of a fiber tip to be accurately placed in the microlaser near-field. Such light funneling within a hybrid structure provides a path for overcoming the diffraction limit in optical energy transfer to the nanoscale and should thus open promising avenues in the nanoscale enhancement and confinement of light in compact architectures, impacting applications such as biosensing, optical trapping, local heating, spectroscopy, and nanoimaging.

  11. A flexible experimental setup for femtosecond time-resolved broad-band ellipsometry and magneto-optics

    SciTech Connect

    Boschini, F.; Hedayat, H.; Piovera, C.; Dallera, C.; Gupta, A.; Carpene, E.

    2015-01-15

    A versatile experimental setup for femtosecond time-resolved ellipsometry and magneto-optical Kerr effect measurements in the visible light range is described. The apparatus is based on the pump-probe technique and combines a broad-band probing beam with an intense near-infrared pump. According to Fresnel scattering matrix formalism, the analysis of the reflected beam at different polarization states of the incident probe light allows one to determine the diagonal and the off-diagonal elements of the dielectric tensor in the investigated sample. Moreover, the pump-probe method permits to study the dynamics of the dielectric response after a short and intense optical excitation. The performance of the experimental apparatus is tested on CrO{sub 2} single crystals as a benchmark.

  12. Electrically-programmable diffraction grating

    DOEpatents

    Ricco, Antonio J.; Butler, Michael A.; Sinclair, Michael B.; Senturia, Stephen D.

    1998-01-01

    An electrically-programmable diffraction grating. The programmable grating includes a substrate having a plurality of electrodes formed thereon and a moveable grating element above each of the electrodes. The grating elements are electrostatically programmable to form a diffraction grating for diffracting an incident beam of light as it is reflected from the upper surfaces of the grating elements. The programmable diffraction grating, formed by a micromachining process, has applications for optical information processing (e.g. optical correlators and computers), for multiplexing and demultiplexing a plurality of light beams of different wavelengths (e.g. for optical fiber communications), and for forming spectrometers (e.g. correlation and scanning spectrometers).

  13. Ellipsometry of Colloidal Solutions: New Experimental Setup and Application to Metallic Colloids.

    PubMed

    Battie, Yann; Stchakovsky, Michel; En Naciri, Aotmane; Akil, Suzanna; Chaoui, Nouari; Broch, Laurent

    2017-08-01

    An ellipsometric cell is developed to simultaneously determine the shape distribution, the volume fraction, and the complex refractive index of gold and silver colloids. Simulation reveals that this cell drastically improves the detection limit of ellipsometry. Indeed, Ag and Au nanoparticles (NPs) are detected at the ppmv level. We demonstrate that the NPs shape distribution can be estimated from ellipsometric measurements by analyzing them with a shape distributed effective medium theory (SDEMT). The obtained distributions from ellipsometry are in agreement with those deduced from transmission electron microcopy (TEM). Contrary to TEM, ellipsometry probes a large number of NPs estimated at about 10(11) NPs. Finally, we show that the complex refractive index of colloids as determined from ellipsometry is sensitive to the optical properties of the solvent and the plasmonic properties of NPs.

  14. X-ray diffraction analysis of the effects of myosin regulatory light chain phosphorylation and butanedione monoxime on skinned skeletal muscle fibers

    PubMed Central

    Kimura, Masako; Li, Zhao-bo; Ohno, Tetsuo; Takemori, Shigeru; Hoh, Joseph F. Y.; Yagi, Naoto

    2016-01-01

    The phosphorylation of the myosin regulatory light chain (RLC) is an important modulator of skeletal muscle performance and plays a key role in posttetanic potentiation and staircase potentiation of twitch contractions. The structural basis for these phenomena within the filament lattice has not been thoroughly investigated. Using a synchrotron radiation source at SPring8, we obtained X-ray diffraction patterns from skinned rabbit psoas muscle fibers before and after phosphorylation of myosin RLC in the presence of myosin light chain kinase, calmodulin, and calcium at a concentration below the threshold for tension development ([Ca2+] = 10−6.8 M). After phosphorylation, the first myosin layer line slightly decreased in intensity at ∼0.05 nm−1 along the equatorial axis, indicating a partial loss of the helical order of myosin heads along the thick filament. Concomitantly, the (1,1/1,0) intensity ratio of the equatorial reflections increased. These results provide a firm structural basis for the hypothesis that phosphorylation of myosin RLC caused the myosin heads to move away from the thick filaments towards the thin filaments, thereby enhancing the probability of interaction with actin. In contrast, 2,3-butanedione monoxime (BDM), known to inhibit contraction by impeding phosphate release from myosin, had exactly the opposite effects on meridional and equatorial reflections to those of phosphorylation. We hypothesize that these antagonistic effects are due to the acceleration of phosphate release from myosin by phosphorylation and its inhibition by BDM, the consequent shifts in crossbridge equilibria leading to opposite changes in abundance of the myosin-ADP-inorganic phosphate complex state associated with helical order of thick filaments. PMID:26911280

  15. Light-induced isomerization causes an increase in the chromophore tilt in the M intermediate of bacteriorhodopsin: a neutron diffraction study.

    PubMed Central

    Hauss, T; Büldt, G; Heyn, M P; Dencher, N A

    1994-01-01

    Bacteriorhodopsin (BR) was regenerated with two selectively deuterated retinals, one with 11 deuterons in the beta-ionone ring (D11) and the other with 5 deuterons (D5) at the end of the polyene chain closest to the Schiff base at carbon atoms C-14, C-15, and C-20. Both label positions (centers of deuteration) were obtained from difference Fourier maps of projections onto the plane of the membrane by neutron diffraction at 90 K, both in the light-adapted ground-state BR568 and in the photocycle intermediate M412. To retard the decay of M412, purple membrane films were soaked in 0.1 M or 1 M guanidine hydrochloride at pH 9.6. M412 was produced by illuminating oriented membrane films at physiological temperature (278 K), followed by rapid cooling to 90 K in the absence of light. The results show that in the projected structure the ring position is unaltered during the transition from BR568 to M412, whereas the position of the D5 label shifts by 1.4 +/- 0.9 A toward the ring. The shortened interlabel distance in the projected structure for the M412 state implies that as a result of the all-trans/13-cis isomerization, the C-5 to C-13 part of the polyene chain tilts out of the plane of the membrane toward the cytoplasm by about 11 degrees +/- 6 degrees. Pairwise comparison of data sets with the same retinal for the two photocycle states M412 and BR568 leads to four difference-density maps for the protein, which are in agreement with previous work. They show changes in the protein density near helices G and F. PMID:7991546

  16. In situ magneto-optical ellipsometry data analysis for films growth control

    NASA Astrophysics Data System (ADS)

    Maximova, O. A.; Kosyrev, N. N.; Varnakov, S. N.; Lyaschenko, S. A.; Yakovlev, I. A.; Tarasov, I. A.; Shevtsov, D. V.; Maximova, O. M.; Ovchinnikov, S. G.

    2017-10-01

    In this work we present the way of ferromagnetic films study by means of magneto-ellipsometry. The method of interpretation of in situ magneto-optical ellipsometry spectra for real time growth control is described. The method has been successfully tested on Si /SiO2 / Fe films within the model of a homogeneous semi-infinite medium. As a result, the dielectric tensor components for Fe layer were calculated using a developed approach.

  17. Imaging Mie ellipsometry: dynamics of nanodust clouds in an argon-acetylene plasma

    NASA Astrophysics Data System (ADS)

    Greiner, Franko; Carstensen, Jan; Köhler, Nils; Pilch, Iris; Ketelsen, Helge; Knist, Sascha; Piel, Alexander

    2012-12-01

    For the in situ analysis of nano-sized particles in a laboratory plasma, Mie ellipsometry is a well established technique. We present a simple setup with two CCD cameras to gain online spatiotemporal resolved information of the growth dynamics of particles which are produced by plasma chemical processes in an argon-acetylene plasma. Imaging Mie ellipsometry proves to be a powerful technique to study the growth processes of nanodust in all its details.

  18. Newton's diffraction measurements

    NASA Astrophysics Data System (ADS)

    Nauenberg, Michael

    2004-05-01

    This year marks the tercentenary of the publication of Newton's Opticks which contains his celebrated theory and experiments of light and colors as it evolved from the first published version in 1672. It is still fairly unknown, however, that in this book Newton also reported his experiments on diffraction fringes obtained from various "slender" objects placed in a beam of sunlight. These experiments posed an insurmountable difficulty to Newton's corpuscular theory of light, which failed to account for his observations. This failure explains the long delay in the publication of this book. In my talk I will compare Newton's experimental results on diffraction with the predictions of Fresnel's wave theory to demonstrate that his measurements were remarkable accurate. Eventually these measurements paved the way for Young's correct explanation of the diffraction fringes as a wave interference phenomenon.

  19. Generation of 3.5 W of diffraction-limited green light from SHG of a single tapered diode laser in a cascade of nonlinear crystals

    NASA Astrophysics Data System (ADS)

    Hansen, Anders K.; Jensen, Ole B.; Sumpf, Bernd; Erbert, Götz; Unterhuber, Angelika; Drexler, Wolfgang; Andersen, Peter E.; Petersen, Paul Michael

    2014-02-01

    Many applications, e.g., within biomedicine stand to benefit greatly from the development of diode laser-based multi- Watt efficient compact green laser sources. The low power of existing diode lasers in the green area (about 100 mW) means that the most promising approach remains nonlinear frequency conversion of infrared tapered diode lasers. Here, we describe the generation of 3.5 W of diffraction-limited green light from SHG of a single tapered diode laser, itself yielding 10 W at 1063 nm. This SHG is performed in single pass through a cascade of two PPMgO:LN crystals with re-focusing and dispersion compensating optics between the two nonlinear crystals. In the low-power limit, such a cascade of two crystals has the theoretical potential for generation of four times as much power as a single crystal without adding significantly to the complexity of the system. The experimentally achieved power of 3.5 W corresponds to a power enhancement greater than 2 compared to SHG in each of the crystals individually and is the highest visible output power generated by frequency conversion of a single diode laser. Such laser sources provide the necessary pump power for biophotonics applications, such as optical coherence tomography or multimodal imaging devices, e.g., FTCARS-OCT, based on a strongly pumped ultrafast Ti:Sapphire laser.

  20. Fresnel diffraction plates are simple and inexpensive

    NASA Technical Reports Server (NTRS)

    Hoover, R. B.

    1967-01-01

    Fresnel plate demonstrates diffraction phenomena simply and inexpensively. A large number of identical diffracting apertures are made in random orientation on photographic film. When a small source of light is viewed through the plate, the diffraction pattern typical of the diffracting aperture is readily seen.

  1. Optical dielectric response of gallium nitride studied by variable angle spectroscopy ellipsometry

    SciTech Connect

    Yao, H.; Yan, C.H.; Jenkinson, H.A.; Zavada, J.M.; Speck, J.S.; Denbaars, S.P.

    1997-12-31

    Variable angle spectroscopic ellipsometry (VASE) and transmission measurements have been employed to study the dielectric response of gallium nitride (GaN) thin films -- an important material for light emitting diodes (LEDs) and laser diodes applications. The GaN films were grown by atmosphere pressure metal organic chemical vapor deposition (MOCVD) on c-plane sapphire substrates ({alpha}-Al{sub 2}O{sub 3}). Room temperature VASE measurements were made, in the range of 0.75 to 5.5eV, at the angle of incidence of 73, 75, and 77 degree, respectively. Evidence of anisotropy is observed especially in the spectral range under the band gap ({approximately}3.4 eV), reflecting the nature of wurtzite crystal structure of GaN. The ordinary dielectric function {var_epsilon}{sub {perpendicular}}({omega}) of GaN were obtained through the analysis of transmission and VASE data in the range below and above the band gap. The thickness of these GaN films is also determined via the analysis.

  2. B-spline parametrization of the dielectric function applied to spectroscopic ellipsometry on amorphous carbon

    SciTech Connect

    Weber, J. W.; Hansen, T. A. R.; Sanden, M. C. M. van de; Engeln, R.

    2009-12-15

    The remote plasma deposition of hydrogenated amorphous carbon (a-C:H) thin films is investigated by in situ spectroscopic ellipsometry (SE). The dielectric function of the a-C:H film is in this paper parametrized by means of B-splines. In contrast with the commonly used Tauc-Lorentz oscillator, B-splines are a purely mathematical description of the dielectric function. We will show that the B-spline parametrization, which requires no prior knowledge about the film or its interaction with light, is a fast and simple-to-apply method that accurately determines thickness, surface roughness, and the dielectric constants of hydrogenated amorphous carbon thin films. Analysis of the deposition process provides us with information about the high deposition rate, the nucleation stage, and the homogeneity in depth of the deposited film. Finally, we show that the B-spline parametrization can serve as a stepping stone to physics-based models, such as the Tauc-Lorentz oscillator.

  3. Spectroscopic ellipsometry studies of HF treated Si (100) surfaces

    NASA Astrophysics Data System (ADS)

    Yao, Huade; Woollam, John A.; Alterovitz, Samuel A.

    1993-08-01

    Both ex situ and in situ spectroscopic ellipsometry (SE) measurements were employed to investigate the effects of HF cleaning on Si surfaces. The hydrogen-terminated (H-terminated) Si surface was modeled as an equivalent dielectric layer, and monitored in real time by SE measurements. The SE analyses indicate that after a 20-s 9:1 HF dip without rinse, the Si(100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si(100) surface was observed, in an ultrahigh vacuum (UHV) chamber, and analyzed by the in situ SE. Evidence for desorption of the H-terminated Si surface-layer, after being heated to approximately 550 C in the UHV chamber, is presented and discussed. This is the first use of an ex situ and in situ real-time, nondestructive technique capable of showing state of passivation, the rate of reoxidation, and the surface roughness of the H-terminated Si surfaces.

  4. Spectroscopic ellipsometry studies of HF treated Si (100) surfaces

    NASA Astrophysics Data System (ADS)

    Yao, Huade; Woollam, John A.; Alterovitz, Samuel A.

    1993-06-01

    Both ex situ and in situ spectroscopic ellipsometry (SE) measurements were employed to investigate the effect of HF cleaning on Si surfaces. The hydrogen-terminated (H-terminated) Si surface was modeled as an equivalent dielectric layer, and monitored in real time by SE measurements. The SE analyses indicate that, after a 20-sec 9:1 HF dip without rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed, in an ultrahigh vacuum chamber (UHV), and analyzed by the in situ SE. Evidence for desorption of the H-terminated Si surface layer, after being heated to about 550 C in the UHV chamber, is presented and discussed. This is the first use of an ex situ and in situ real-time, nondestructive technique capable of showing state of passivation, the rate of reoxidation, and the surface roughness of the H-terminated Si surfaces.

  5. Terahertz time-domain spectroscopic ellipsometry: instrumentation and calibration.

    PubMed

    Neshat, Mohammad; Armitage, N P

    2012-12-17

    We present a new instrumentation and calibration procedure for terahertz time-domain spectroscopic ellipsometry (THz-TDSE) that is a newly established characterization technique. The experimental setup is capable of providing arbitrary angle of incidence in the range of 15°-85° in the reflection geometry, and with no need for realignment. The setup is also configurable easily into transmission geometry. For this setup, we successfully used hollow core photonic band gap fiber with no pre-chirping in order to deliver a femtosecond laser into a THz photoconductive antenna detector, which is the first demonstration of this kind. The proposed calibration scheme can compensate for the non-ideality of the polarization response of the THz photoconductive antenna detector as well as that of wire grid polarizers used in the setup. In the calibration scheme, the ellipsometric parameters are obtained through a regression algorithm which we have adapted from the conventional regression calibration method developed for rotating element optical ellipsometers, and used here for the first time for THz-TDSE. As a proof-of-principle demonstration, results are presented for a high resistivity silicon substrate as well as an opaque Si substrate with a high phosphorus concentration. We also demonstrate the capacity to measure a few micron thick grown thermal oxide on top of Si. Each sample was characterized by THz-TDSE in reflection geometry with different angle of incidence.

  6. Structural investigations of human hairs by spectrally resolved ellipsometry

    NASA Astrophysics Data System (ADS)

    Chan, Danny; Schulz, Benjamin; Rübhausen, Michael; Wessel, Sonya; Wepf, Roger

    2006-01-01

    Human hair is a biological layered system composed of two major layers, the cortex and the cuticle. We show spectrally resolved ellipsometry measurements of the ellipsometric parameters Ψ and Δ of single human hairs. The spectra reflect the layered nature of hair and the optical anisotropy of the hair's structure. In addition, measurements on strands of human hair show a high reproducibility of the ellipsometric parameters for different hair fiber bundles from the same person. Based on the measurements, we describe a dielectric model of hair that explains the spectra in terms of the dielectric properties of the major parts of hair and their associated layer thicknesses. In addition, surface roughness effects modeled by a roughness layer with a complex refractive index given by an effective medium approach can be seen to have a significant effect on the measurements. We derive values for the parameters of the cuticle surface roughness layer of the thickness dACu=273 to 360 nm and the air inclusion fA=0.6 to 5.7%.

  7. Structural investigations of human hairs by spectrally resolved ellipsometry

    NASA Astrophysics Data System (ADS)

    Schulz, Benjamin; Chan, D.; Ruebhausen, M.; Wessel, S.; Wepf, R.

    2006-03-01

    Human hair is a biological layered system composed of two major layers, the cortex and the cuticle. We show spectrally resolved ellipsometry measurements of the ellipsometric parameters ψ and δ of single human hairs. The spectra reflect the layered nature of hair and the optical anisotropy of the hair’s structure. In addition, measurements on strands of human hair show a high reproducibility of the ellipsometric parameters for different hair fiber bundles from the same person. Based on the measurements, we develop a model of the dielectric function of hair that explains the spectra. This model includes the dielectric properties of the cuticle and cortex as well as their associated layer thicknesses. In addition, surface roughness effects modelled by a roughness layer with an complex refractive index given by an effective medium approach can have a significant effect on the measurements. We derive values for the parameters of the cuticle surface roughness layer of the thickness dACu= 273-360 nm and the air inclusion fA= 0.6 -5.7%. [1] accepted for publication in J. Biomed Opt., 2005

  8. Photomask CD and LER characterization using Mueller matrix spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Heinrich, A.; Dirnstorfer, I.; Bischoff, J.; Meiner, K.; Ketelsen, H.; Richter, U.; Mikolajick, T.

    2014-10-01

    Critical dimension and line edge roughness on photomask arrays are determined with Mueller matrix spectroscopic ellipsometry. Arrays with large sinusoidal perturbations are measured for different azimuth angels and compared with simulations based on rigorous coupled wave analysis. Experiment and simulation show that line edge roughness leads to characteristic changes in the different Mueller matrix elements. The influence of line edge roughness is interpreted as an increase of isotropic character of the sample. The changes in the Mueller matrix elements are very similar when the arrays are statistically perturbed with rms roughness values in the nanometer range suggesting that the results on the sinusoidal test structures are also relevant for "real" mask errors. Critical dimension errors and line edge roughness have similar impact on the SE MM measurement. To distinguish between both deviations, a strategy based on the calculation of sensitivities and correlation coefficients for all Mueller matrix elements is shown. The Mueller matrix elements M13/M31 and M34/M43 are the most suitable elements due to their high sensitivities to critical dimension errors and line edge roughness and, at the same time, to a low correlation coefficient between both influences. From the simulated sensitivities, it is estimated that the measurement accuracy has to be in the order of 0.01 and 0.001 for the detection of 1 nm critical dimension error and 1 nm line edge roughness, respectively.

  9. Spectroscopic ellipsometry studies of HF treated Si (100) surfaces

    NASA Technical Reports Server (NTRS)

    Yao, Huade; Woollam, John A.; Alterovitz, Samuel A.

    1993-01-01

    Both ex situ and in situ spectroscopic ellipsometry (SE) measurements were employed to investigate the effects of HF cleaning on Si surfaces. The hydrogen-terminated (H-terminated) Si surface was modeled as an equivalent dielectric layer, and monitored in real time by SE measurements. The SE analyses indicate that after a 20-s 9:1 HF dip without rinse, the Si(100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si(100) surface was observed, in an ultrahigh vacuum (UHV) chamber, and analyzed by the in situ SE. Evidence for desorption of the H-terminated Si surface-layer, after being heated to approximately 550 C in the UHV chamber, is presented and discussed. This is the first use of an ex situ and in situ real-time, nondestructive technique capable of showing state of passivation, the rate of reoxidation, and the surface roughness of the H-terminated Si surfaces.

  10. Genesis Silicon Carbide Concentrator Target 60003 Preliminary Ellipsometry Mapping Results

    NASA Technical Reports Server (NTRS)

    Calaway, M. J.; Rodriquez, M. C.; Stansbery, E. K.

    2007-01-01

    The Genesis concentrator was custom designed to focus solar wind ions primarily for terrestrial isotopic analysis of O-17/O-16 and O-18/O-16 to +/-1%, N-15/N-14 to +/-1%, and secondarily to conduct elemental and isotopic analysis of Li, Be, and B. The circular 6.2 cm diameter concentrator target holder was comprised of four quadrants of highly pure semiconductor materials that included one amorphous diamond-like carbon, one C-13 diamond, and two silicon carbide (SiC). The amorphous diamond-like carbon quadrant was fractured upon impact at Utah Test and Training Range (UTTR), but the remaining three quadrants survived fully intact and all four quadrants hold an important collection of solar wind. The quadrants were removed from the target holder at NASA Johnso n Space Center Genesis Curation Laboratory in April 2005, and have been housed in stainless steel containers under continual nitrogen purge since time of disintegration. In preparation for allocation of a silicon carbide target for oxygen isotope analyses at UCLA, the two SiC targets were photographed for preliminary inspection of macro particle contamination from the hard non-nominal landing as well as characterized by spectroscopic ellipsometry to evaluate thin film contamination. This report is focused on Genesis SiC target sample number 60003.

  11. Microcrystalline silicon thin films studied using spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Kang, T. D.; Lee, Hosun; Park, S. J.; Jang, J.; Lee, Soonil

    2002-09-01

    We used spectroscopic ellipsometry to characterize four different microcrystalline silicon (muc-Si) films, which were fabricated by crystallizing a-Si:H films predeposited on glass substrates using solid phase crystallization (SPC), excimer laser annealing (ELA), Ni induced silicide-mediated crystallization (Ni-SMC), and field enhanced silicide-mediated crystallization (FESMC) method, respectively. A linear regression analysis, which took the effective dielectric function of muc-Si layer into account using effective medium approximation, showed that all these films were homogeneous throughout their thickness except the oxide overlayers, and completely crystallized regardless of the crystallization method. In our linear regression analysis, the complex dielectric function of silicon microcrystallites was represented by the Adachi model dielectric function (MDF) [T. Suzuki and S. Adachi, Jpn. J. Appl. Phys., Part1 32, 4900 (1993)], and the broadening parameters of the critical points (CPs) in MDF were allowed to vary. The dielectric function of silicon microcrystallites showed systematic broadening and shrinking of the peak features corresponding to the E1 and E2 CPs, from which we concluded that the average microcrystallite size increased in the order of SPC, ELA, Ni-SMC, and FESMC muc-Si. The Raman spectra and the transmission-electron-microscopy images of these films also supported the idea of systematic variation in the microcrystallite size.

  12. Imaging spectroscopic ellipsometry of MoS2

    NASA Astrophysics Data System (ADS)

    Funke, S.; Miller, B.; Parzinger, E.; Thiesen, P.; Holleitner, A. W.; Wurstbauer, U.

    2016-09-01

    Micromechanically exfoliated mono- and multilayers of molybdenum disulfide (MoS2) are investigated by spectroscopic imaging ellipsometry. In combination with knife edge illumination, MoS2 flakes can be detected and classified on arbitrary flat and also transparent substrates with a lateral resolution down to 1-2 µm. The complex dielectric functions from mono- and trilayer MoS2 are presented. They are extracted from a multilayer model to fit the measured ellipsometric angles employing an anisotropic and an isotropic fit approach. We find that the energies of the critical points of the optical constants can be treated to be independent of the utilized model, whereas the magnitude of the optical constants varies with the used model. The anisotropic model suggests a maximum absorbance for a MoS2 sheet supported by sapphire of about 14% for monolayer and of 10% for trilayer MoS2. Furthermore, the lateral homogeneity of the complex dielectric function for monolayer MoS2 is investigated with a spatial resolution of 2 µm. Only minor fluctuations are observed. No evidence for strain, for a significant amount of disorder or lattice defects can be found in the wrinkle-free regions of the MoS2 monolayer from complementary µ-Raman spectroscopy measurements. We assume that the minor lateral variation in the optical constants are caused by lateral modification in the van der Waals interaction presumably caused by the preparation using micromechanical exfoliation and viscoelastic stamping.

  13. Polypeptide multilayer self-assembly studied by ellipsometry.

    PubMed

    Craig, Marina; Holmberg, Krister; Le Ru, Eric; Etchegoin, Pablo

    2014-01-01

    A polypeptide nanofilm made by layer-by-layer (LbL) self-assembly was built on a surface that mimics nonwoven, a material commonly used in wound dressings. Poly-L-lysine (PLL) and poly-L-glutamic acid (PLGA) are the building blocks of the nanofilm, which is intended as an enzymatically degradable lid for release of bactericides to chronic wounds. Chronic wounds often carry infection originating from bacteria such as Staphylococcus aureus and a release system triggered by the degree of infection is of interest. The dry nanofilm was studied with ellipsometry. The thickness of the nanofilm was 60% less in its dry state than in its wet state. The measurements showed that a primer was not necessary to build a stable nanofilm, which is practically important in our case because a nondegradable primer is highly unwanted in a wound care dressing. Added V8 (glutamyl endopeptidase) enzymes only showed adsorption on the nanofilm at room temperature, indicating that the PLL/PLGA "lid" may remain intact until the dressing has been filled with wound exudate at the elevated temperature typical of that of the wound.

  14. Inversion of ellipsometry data using constrained spline analysis.

    PubMed

    Gilliot, Mickaël

    2017-02-01

    Ellipsometry is a highly sensitive and powerful optical technique of thin film characterization. However, the indirect and nonlinear character of the ellipsometric equations requires numerical extraction of interesting information, such as thicknesses and optical constants of unknown layers. A method is described to perform the inversion of ellipsometric spectra for the simultaneous determination of thickness and optical constants without requiring particular assumptions about the shape of a model dielectric function like in the traditional method of data fitting. The method is based on a Kramers-Kronig consistent description of the imaginary part of the dielectric function using a set of points joined by pieces of third-degree polynomials. Particular connection relations constrain the shape of the constructed curve to a physically meaningful curve avoiding oscillations of natural cubic splines. The connection ordinates conditioning the shape of the dielectric function can be used, together with unknown thickness or roughness, as fitting parameters with no restriction on the material nature. Typical examples are presented concerning metal and semiconductors.

  15. Characterization by spectroscopic Ellipsometry, the physical properties of silver nanoparticles.

    NASA Astrophysics Data System (ADS)

    Coanga, Jean-Maurice

    2013-04-01

    Physicists are able to change their minds through their experiments. I think it is time to go kick the curse and go further in research if we want a human future. I work in the Nano-Optics and Plasmonics research. I defined with ellipsomètrie the structure of new type of Nano particles of silver. It's same be act quickly to replace the old dirty leaded electronic-connexion chip and by the other hand to find a new way for the heath care of cancer disease by nanoparticles the next killers of bad cells. Silver nanoparticle layers are obtained by Spark Plasma Sintering are investigated as an alternative to lead alloy based material for solder joint in power mechatronics modules. These layers are characterized by mean of conventional techniques that is the dilatometry technique, the resistivity measurement through the van der Pauw method, and the flash laser technique. Furthermore, the nanoparticles of silver layer are deeply studied by UV-Visible spectroscopic ellipsometry. Spectroscopic angles parameters are determined in function of temperature and dielectric constants are deduced and analyzed through an optical model which takes into account a Drude and a Lorentz component within the Bruggeman effective medium approximation (EMA). The relaxation times and the electrical conductivity are plot in function of temperature. The obtained electrical conductivity give significant result in good agreement to those reported by four points electrical measurement method.

  16. Lighting.

    SciTech Connect

    United States. Bonneville Power Administration.

    1992-09-01

    Since lighting accounts for about one-third of the energy used in commercial buildings, there is opportunity to conserve. There are two ways to reduce lighting energy use: modify lighting systems so that they used less electricity and/or reduce the number of hours the lights are used. This booklet presents a number of ways to do both. Topics covered include: reassessing lighting levels, reducing lighting levels, increasing bulb & fixture efficiency, using controls to regulate lighting, and taking advantage of daylight.

  17. Monitoring Photodeposition of Polymer Films from Diacetylene Monomer Solutions Using In Situ Real-Time Spectroscopic Ellipsometry

    NASA Technical Reports Server (NTRS)

    Hui, Du; Kim, Jin-Sook; Kim, Yeon-Taik; An, Ilsin; Paley, Mark S.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Photodeposition of thin polymer (PDAMNA) films from diacetylene monomer (DAMNA) solutions onto gold coated silica substrates with UV light was studied using the technique of in-situ real time spectroscopic ellipsometry. The dielectric function of PDAMNA was determined; and the thickness of the growing PDAMNA films over a 4 hour time interval was determined using a linear regression fit of the experimental data to a homogeneous four phase optical model. It was found that stirring the solution dramatically lowers the rate of film deposition, suggesting that convection can affect the attachment kinetics of the film to the substrate. Lastly, the morphology of the PDAMNA films was examined using non-contact mode atomic force microscopy.

  18. Effect of Ta concentration on the refractive index of TiO{sub 2}:Ta studied by spectroscopic ellipsometry

    SciTech Connect

    Nurfani, Eka Kurniawan, Robi; Muhammady, Shibghatullah; Marlina, Resti; Sutjahja, Inge M.; Winata, Toto; Rusydi, Andrivo; Darma, Yudi

    2016-04-19

    We have investigated optical properties of Ta-doped TiO{sub 2} thin film on LaAlO{sub 3} (LAO) substrate using Spectroscopic Ellipsometry (SE) at room temperature. Amplitude ratio Ψ and phase difference L1 between p- and s- polarized light waves are obtained by multiple incident angles measurement (60°, 70°, and 80°) at energy range of 0.5 – 6.5 eV. In order to obtain optical properties for every Ta concentrations (0.01, 0.4, and 5 at. %), multilayer modelling was performed simultaneously by using Drude-Lorentz model. Refractive index and optical dispersion parameters were determined by Wemple-DiDomenico relation. In general, refractive index at zero photon energy n(0) increases by increasing Ta concentration. Furthermore, optical band gap shows a significant increasing due to presence of Ta dopant. In addition, other optical constants are discussed as well.

  19. Investigation Of Far-Field Diffraction

    NASA Technical Reports Server (NTRS)

    Wang, Yaujen; Scholl, Marija S.

    1993-01-01

    Report describes experimental investigation of far-field diffracton by normally illuminated circular apertures with diameters of several wavelengths of incident light. Purpose of investigation to determine whether Keller's "geometrical" theory of diffraction valid for diffraction phenomena of this kind.

  20. Diffractive optical elements designed for highly precise far-field generation in the presence of artifacts typical for pixelated spatial light modulators

    NASA Astrophysics Data System (ADS)

    Milewski, Gabriel; Engström, David; Bengtsson, Jörgen

    2007-01-01

    Diffractive optical elements (DOEs) realized by spatial light modulators (SLMs) often have features that distinguish them from most conventional, static DOEs: strong coupling between phase and amplitude modulation, a modulation versus steering parameter characteristic that may not be precisely known (and may vary with, e.g., temperature), and deadspace effects and interpixel cross talk. For an optimal function of the DOE, e.g. as a multiple-beam splitter, the DOE design must account for these artifacts. We present an iterative design method in which the optimal setting of each SLM pixel is carefully chosen by considering the SLM artifacts and the design targets. For instance, the deadspace-interpixel effects are modeled by dividing the pixel to be optimized, and its nearest neighbors, into a number of subareas, each with its unique response and far-field contribution. Besides the customary intensity control, the design targets can also include phase control of the optical field in one or more of the beams in the beam splitter. We show how this can be used to cancel a strong unwanted zeroth-order beam, which results from using a slightly incorrect modulation characteristic for the SLM, by purposely sending a beam in the same direction but with the opposite phase. All the designs have been implemented on the 256 × 256 central pixels of a reflective liquid crystal on silicon SLM with a selected input polarization state and a direction of transmission axis of the output polarizer such that for the available different pixel settings a phase modulation of ˜2π rad could be obtained, accompanied by an intensity modulation depth as high as >95%.

  1. Spectral ellipsometry of GaSb: Experiment and modelling

    SciTech Connect

    Charache, G.W.; Mu {tilde n}oz, M.; Wei, K.; Pollak, F.H.; Freeouf, J.L.

    1999-05-01

    The optical constants {epsilon}(E)[{equals}{epsilon}{sub 1}(E) + i{epsilon}{sub 2}(E)] of single crystal GaSb at 300K have been measured using spectral ellipsometry in the range of 0.3--5.3 eV. The {epsilon}(E) spectra displayed distinct structures associated with critical points (CPs) at E{sub 0}(direct gap), spin-orbit split E{sub 0} + {Delta}{sub 0} component, spin-orbit split (E{sub 1}), E{sub 1} + {Delta}{sub 1} and (E{sub 0}{prime}), E{sub 0}{prime} + {Delta}{sub 0}{prime} doublets, as well as E{sub 2}. The experimental data over the entire measured spectral range (after oxide removal) has been fit using the Holden model dielectric function [Phys.Rev.B 56, 4037 (1997)] based on the electronic energy-band structure near these CPs plus excitonic and band-to-band Coulomb enhancement effects at E{sub 0}, E{sub 0} + {Delta}{sub 0}and the E{sub 1}, E{sub 1} + {Delta}{sub 1} doublet. In addition to evaluating the energies of these various band-to-band CPs, information about the binding energy (R{sub 1}) of the two-dimensional exciton related to the E{sub 1}, E{sub 1} + {Delta}{sub 1} CPS was obtained. The value of R{sub 1} was in good agreement with effective mass/{rvec k} {center_dot} {rvec p} theory. The ability to evaluate R{sub 1} has important ramifications for recent first-principles band structure calculations which include exciton effects at E{sub 0}, E{sub 1}, and E{sub 2}.

  2. Analysis of Protein Interactions at Native Chloroplast Membranes by Ellipsometry

    PubMed Central

    Kriechbaumer, Verena; Nabok, Alexei; Mustafa, Mohd K.; Al-Ammar, Rukaiah; Tsargorodskaya, Anna; Smith, David P.; Abell, Ben M.

    2012-01-01

    Membrane bound receptors play vital roles in cell signaling, and are the target for many drugs, yet their interactions with ligands are difficult to study by conventional techniques due to the technical difficulty of monitoring these interactions in lipid environments. In particular, the ability to analyse the behaviour of membrane proteins in their native membrane environment is limited. Here, we have developed a quantitative approach to detect specific interactions between low-abundance chaperone receptors within native chloroplast membranes and their soluble chaperone partners. Langmuir-Schaefer film deposition was used to deposit native chloroplasts onto gold-coated glass slides, and interactions between the molecular chaperones Hsp70 and Hsp90 and their receptors in the chloroplast membranes were detected and quantified by total internal reflection ellipsometry (TIRE). We show that native chloroplast membranes deposited on gold-coated glass slides using Langmuir-Schaefer films retain functional receptors capable of binding chaperones with high specificity and affinity. Taking into account the low chaperone receptor abundance in native membranes, these binding properties are consistent with data generated using soluble forms of the chloroplast chaperone receptors, OEP61 and Toc64. Therefore, we conclude that chloroplasts have the capacity to selectively bind chaperones, consistent with the notion that chaperones play an important role in protein targeting to chloroplasts. Importantly, this method of monitoring by TIRE does not require any protein labelling. This novel combination of techniques should be applicable to a wide variety of membranes and membrane protein receptors, thus presenting the opportunity to quantify protein interactions involved in fundamental cellular processes, and to screen for drugs that target membrane proteins. PMID:22479632

  3. Study of optical Laue diffraction

    NASA Astrophysics Data System (ADS)

    Chakravarthy, Giridhar; Allam, Srinivasa Rao; Satyanarayana, S. V. M.; Sharan, Alok

    2014-10-01

    We present the study of the optical diffraction pattern of one and two-dimensional gratings with defects, designed using desktop pc and printed on OHP sheet using laser printer. Gratings so prepared, using novel low cost technique provides good visual aid in teaching. Diffraction pattern of the monochromatic light (632.8nm) from the grating so designed is similar to that of x-ray diffraction pattern of crystal lattice with point defects in one and two-dimensions. Here both optical and x-ray diffractions are Fraunhofer. The information about the crystalline lattice structure and the defect size can be known.

  4. Study of optical Laue diffraction

    SciTech Connect

    Chakravarthy, Giridhar E-mail: aloksharan@email.com; Allam, Srinivasa Rao E-mail: aloksharan@email.com; Satyanarayana, S. V. M. E-mail: aloksharan@email.com; Sharan, Alok E-mail: aloksharan@email.com

    2014-10-15

    We present the study of the optical diffraction pattern of one and two-dimensional gratings with defects, designed using desktop pc and printed on OHP sheet using laser printer. Gratings so prepared, using novel low cost technique provides good visual aid in teaching. Diffraction pattern of the monochromatic light (632.8nm) from the grating so designed is similar to that of x-ray diffraction pattern of crystal lattice with point defects in one and two-dimensions. Here both optical and x-ray diffractions are Fraunhofer. The information about the crystalline lattice structure and the defect size can be known.

  5. Light beams interaction with highly effective holographic diffraction structure formed in polymer-stabilized liquid crystal under the impact of arbitrarily spatially inhomogeneous electric field

    NASA Astrophysics Data System (ADS)

    Sharangovich, Sergey N.; Semkin, Artem O.

    2016-11-01

    In this work we developed the analytical model of highly effective diffraction on holographic diffraction structures in polymer-stabilized liquid crystals (PSLC) under the impact of arbitrarily inhomogeneous external electric field. The exact self-consistent analytical solutions are obtained by solving the system of coupled-wave equations describing the diffraction process by Riemann's method. They takes into account the electrically-induced phase mismatch changing's inhomogeneity caused by the strong adhesion between liquid crystal molecules and bounding surfaces. According to the obtained relations, numerical simulation of the diffraction characteristics under the influence of external fields with different form of spatial inhomogeneity was made. The simulation results show qualitative compliance with the earlier obtained results.

  6. Comparison of in vitro methods of measuring mucoadhesion: ellipsometry, tensile strength and rheological measurements.

    PubMed

    Ivarsson, David; Wahlgren, Marie

    2012-04-01

    In this work three in vitro methods for the measurement of mucoadhesion have been compared: ellipsometry, tensile strength and rheology. The conditions used for the three methods have been as similar as possible. Six different polymers were investigated: sodium carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), chitosan, polyvinyl pyrrolidone (PVP) and two cross-linked polyacrylic acids, Noveon (hydrophobically modified) and Carbopol. The results showed that PVP did not exhibit mucoadhesion according to any of the methods used. Chitosan, Noveon, Carbopol, CMC and HEC showed good mucoadhesion in the tensile strength and the rheological measurements, but not in the ellipsometry investigation. Chitosan was the only polymer showing good mucoadhesion with the ellipsometry method. No two methods gave the same ranking of mucoadhesive strength of the polymers. The conflicting results obtained with the different methods underline the need for further improvements in existing experimental techniques and theoretical concepts for the correct assessment of mucoadhesive properties.

  7. Spectroscopic rotating compensator ellipsometry in the infrared: retarder design and measurement

    NASA Astrophysics Data System (ADS)

    den Boer, J. H. W. G.; Kroesen, G. M. W.; de Hoog, F. J.

    1997-05-01

    Rotating compensator ellipsometry (RCE) is an approach to ellipsometry that is superior to the widely used rotating analyser ellipsometry (RAE). An essential component in RCE is a retarder that generates a retardance close to 0957-0233/8/5/004/img1. In contrast to RCE at a single wavelength, spectroscopic RCE requires a retarder that performs well over a wide range of the used spectrum. The designed retarder is capable of this and works on the principle of total internal reflection. Making use of this retarder, RCE is tested by measuring the optical characteristics of a Teflon-like layer on an aluminium substrate. The results show good agreement with similar RAE measurements, as well as data calculated from an ellipsometric model.

  8. Spectroscopic ellipsometry analysis of silicon nanotips obtained by electron cyclotron resonance plasma etching.

    PubMed

    Mendoza-Galván, Arturo; Järrendahl, Kenneth; Arwin, Hans; Huang, Yi-Fan; Chen, Li-Chyong; Chen, Kuei-Hsien

    2009-09-10

    Silicon nanotips fabricated by electron cyclotron resonance plasma etching of silicon wafers are studied by spectroscopic ellipsometry. The structure of the nanotips is composed of columns 100-140 nm wide and spaced by about 200 nm. Ellipsometry data covering a wide spectral range from the midinfrared to the visible are described by modeling the nanotip layer as a graded uniaxial film using the Bruggeman effective medium approximation. The ellipsometry data in the infrared range reveal two absorption bands at 754 and 955 cm(-1), which cannot be resolved with transmittance measurements. These bands indicate that the etching process is accompanied with formation of carbonaceous SiC and CH(n) species that largely modify the composition of the original crystalline silicon material affecting the optical response of the nanotips.

  9. Infrared spectroscopic ellipsometry of micrometer-sized SiO2 line gratings

    NASA Astrophysics Data System (ADS)

    Walder, Cordula; Zellmeier, Matthias; Rappich, Jörg; Ketelsen, Helge; Hinrichs, Karsten

    2017-09-01

    For the design and process control of periodic nano-structured surfaces spectroscopic ellipsometry is already established in the UV-VIS spectral regime. The objective of this work is to show the feasibility of spectroscopic ellipsometry in the infrared, exemplarily, on micrometer-sized SiO2 line gratings grown on silicon wafers. The grating period ranges from 10 to about 34 μm. The IR-ellipsometric spectra of the gratings exhibit complex changes with structure variations. Especially in the spectral range of the oxide stretching modes, the presence of a Rayleigh singularity can lead to pronounced changes of the spectrum with the sample geometry. The IR-ellipsometric spectra of the gratings are well reproducible by calculations with the RCWA method (Rigorous Coupled Wave Analysis). Therefore, infrared spectroscopic ellipsometry allows the quantitative characterization and process control of micrometer-sized structures.

  10. Characterization of Liquid Crystal Layer and Cholesteric Film by Renormalized Spectroscopic Ellipsometry

    NASA Astrophysics Data System (ADS)

    Kimura, Munehiro; Kamada, Hirokazu; Onuma, Toshihiko; Akahane, Tadashi

    2009-03-01

    Renormalized transmission spectroscopic ellipsometry (RTSE) is used to evaluate the device parameters of liquid crystal display (LCD). To determine the reduced dielectric and elastic constants, threshold voltage, pretilt angle, cell gap, and surface polar anchoring energy coefficient, symmetrically oblique incidence transmission ellipsometry (SOITE) was applied to vertical-alignment (VA) LCD. It is suggested that the rubbing process on the alignment films for VA LCD does not disturb the measurement of the genuine surface polar anchoring energy coefficient. RTSE is also applicable to the determination of the total twist angle of the cholesteric film.

  11. Photoelectron diffraction

    NASA Astrophysics Data System (ADS)

    Fadley, Charles S.

    1987-01-01

    The use of core-level photoelectron diffraction for structural studies of surfaces and epitaxial overlayers is discussed. Photoelectron diffraction is found to provide several direct and rather unique types of structural information, including the sites and positions of adsorbed atoms; the orientations of small molecules or fragments bound to surfaces; the orientations, layer thicknesses, vertical lattice constants, and degrees of short-range order of epitaxial or partially-epitaxial overlayers; and the presence of short-range spin order in magnetic materials. Specific systems considered are the reaction of oxygen with Ni(001), the growth of epitaxial Cu on Ni(001), the well-defined test case S on Ni(001), and short-range spin order in the antiferromagnet KMnF3. A rather straightforward single scattering cluster (SSC) model also proves capable of quantitatively describing such data, particularly for near-surface species and with corrections for spherical-wave scattering effects and correlated vibrational motion. Promising new directions in such studies also include measurements with high angular resolution and the expanded use of synchrotron radiation.

  12. Reflectometry-Ellipsometry Reveals Thickness, Growth Rate, and Phase Composition in Oxidation of Copper.

    PubMed

    Diaz Leon, Juan J; Fryauf, David M; Cormia, Robert D; Zhang, Min-Xian Max; Samuels, Kathryn; Williams, R Stanley; Kobayashi, Nobuhiko P

    2016-08-31

    The oxidation of copper is a complicated process. Copper oxide develops two stable phases at room temperature and standard pressure (RTSP): cuprous oxide (Cu2O) and cupric oxide (CuO). Both phases have different optical and electrical characteristics that make them interesting for applications such as solar cells or resistive switching devices. For a given application, it is necessary to selectively control oxide thickness and cupric/cuprous oxide phase volume fraction. The thickness and composition of a copper oxide film growing on the surface of copper widely depend on the characteristics of as-deposited copper. In this Research Article, two samples, copper films prepared by two different deposition techniques, electron-beam evaporation and sputtering, were studied. As the core part of the study, the formation of the oxidized copper was analyzed routinely over a period of 253 days using spectroscopic polarized reflectometry-spectroscopic ellipsometry (RE). An effective medium approximation (EMA) model was used to fit the RE data. The RE measurements were complemented and validated by using X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and X-ray diffraction (XRD). Our results show that the two samples oxidized under identical laboratory ambient conditions (RTSP, 87% average relative humidity) developed unique oxide films following an inverse-logarithmic growth rate with thickness and composition different from each other over time. Discussion is focused on the ability of RE to simultaneously extract thickness (i.e., growth rate) and composition of copper oxide films and on plausible physical mechanisms responsible for unique oxidation habits observed in the two copper samples. It appears that extended surface characteristics (i.e., surface roughness and grain boundaries) and preferential crystalline orientation of as-deposited polycrystalline copper films control the growth kinetics of the copper oxide film. Analysis based on a noncontact

  13. Spectroscopic ellipsometry on Si/SiO{sub 2}/graphene tri-layer system exposed to downstream hydrogen plasma: Effects of hydrogenation and chemical sputtering

    SciTech Connect

    Eren, Baran; Fu, Wangyang; Marot, Laurent Calame, Michel; Steiner, Roland; Meyer, Ernst

    2015-01-05

    In this work, the optical response of graphene to hydrogen plasma treatment is investigated with spectroscopic ellipsometry measurements. Although the electronic transport properties and Raman spectrum of graphene change after plasma hydrogenation, ellipsometric parameters of the Si/SiO2/graphene tri-layer system do not change. This is attributed to plasma hydrogenated graphene still being electrically conductive, since the light absorption of conducting 2D materials does not depend on the electronic band structure. A change in the light transmission can only be observed when higher energy hydrogen ions (30 eV) are employed, which chemically sputter the graphene layer. An optical contrast is still apparent after sputtering due to the remaining traces of graphene and hydrocarbons on the surface. In brief, plasma treatment does not change the light transmission of graphene; and when it does, this is actually due to plasma damage rather than plasma hydrogenation.

  14. Raman and ellipsometry spectroscopic analysis of graphene films grown directly on Si substrate via CVD technique for estimating the graphene atomic planes number

    NASA Astrophysics Data System (ADS)

    Al-Hazmi, F. S.; Beall, Gary W.; Al-Ghamdi, A. A.; Alshahrie, Ahmed; Shokr, F. S.; Mahmoud, Waleed E.

    2016-08-01

    Two reliable approaches for estimating the number of atomic planes of graphene films grown on Si substrate were demonstrated by Raman and ellipsometry spectroscopies. The first approach depends on the measurement of the ratio of the integrated Raman scattering intensity of the graphene G band to the optical phonon band of Si substrate (IG/ISi). The second approach belongs to ellipsometry measurement of the ratio of the amplitude of the reflected polarized light from the surface of the graphene films to the amplitude of reflected polarized light from the surface of the Si substrate (ΨG/ΨSi). These two approaches could efficiently recognize the number of atomic planes in the graphene films (1 ≤ n ≤ 10). The results were compared with atomic force microscopy (AFM) measurement and showed a linear regression with slope of 0.36 ± 0.01 nm/graphene layer. The Two approaches will open a new avenue to efficiently count the number of graphene layers during the preparation process.

  15. Anatomy of μc-Si thin films by plasma enhanced chemical vapor deposition: An investigation by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Losurdo, M.; Rizzoli, R.; Summonte, C.; Cicala, G.; Capezzuto, P.; Bruno, G.

    2000-09-01

    A detailed analysis of the anatomy of microcrystalline (μc-Si) films deposited by plasma enhanced chemical vapor deposition from both SiF4-H2 and SiH4-H2 mixtures is performed by spectroscopic ellipsometry (SE). Specifically, the μc-Si film anatomy consists of an interface layer at the substrate/μc-Si bulk layer, a bulk μc-Si layer, and a surface porous layer. All these layers have their own microstructures, which need to be highlighted, since it is this overall anatomy which determines the optical properties of μc-Si films. The ability of SE to discriminate the complex microstructure of μc-Si thin films is emphasized also by the comparison with the x-ray diffraction data which cannot provide unambiguous information regarding the distribution of the crystalline and the amorphous phases along the μc-Si film thickness. Through the description of the μc-Si film anatomy, information on the effect of the growth precursors (SiF4 or SiH4) and of the substrate (c-Si or Corning glass) on the growth dynamics can be obtained. The key role of the F-atoms density and, therefore, of the etching-to-deposition competition on the growth mechanism and film microstructure is highlighted.

  16. Quantifying protein adsorption on combinatorially sputtered Al-, Nb-, Ta- and Ti-containing films with electron microprobe and spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Byrne, T. M.; Lohstreter, L.; Filiaggi, M. J.; Bai, Zhijun; Dahn, J. R.

    2009-04-01

    Although metallic biomaterials are widely used, systematic studies of protein adsorption onto such materials are generally lacking. Combinatorial binary libraries of Al 1-xNb x, Al 1-xTa x, Al 1-xTi x, Nb 1-xTa x, Nb 1-xTi x, and Ta 1-xTi x (0 ⩽ x ⩽ 1) and a ternary library of Al 1-xTi xTa y (0 ⩽ x ⩽ 1 and 0 ⩽ y ⩽ 0.7), along with their corresponding pure element films were sputtered onto glass substrates using a unique magnetron sputtering technique. Films were characterized with wavelength-dispersive spectroscopy (WDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Fibrinogen and albumin adsorption amounts were measured by wavelength-dispersive spectroscopy (WDS) and spectroscopic ellipsometry (SE) equipment, both high throughput techniques with automated motion stage capabilities. Protein adsorption onto these films was found to be closely correlated to the alumina surface fraction, with high alumina content at the surface leading to low amounts of adsorbed fibrinogen and albumin. Protein adsorption amounts obtained with WDS and SE were in good agreement for all films.

  17. Ellipsometry with polarisation analysis at cryogenic temperatures inside a vacuum chamber

    SciTech Connect

    Bauer, S.; Grees, B.; Spitzer, D.; Beck, M.; Bottesch, R.; Ortjohann, H.-W.; Schäfer, T.; Wegmann, A.; Zbořil, M.; Weinheimer, C.; Ostrick, B.; Telle, H. H.

    2013-12-15

    In this paper we describe a new variant of null ellipsometry to determine thicknesses and optical properties of thin films on a substrate at cryogenic temperatures. In the PCSA arrangement of ellipsometry the polarizer and the compensator are placed before the substrate and the analyzer after it. Usually, in the null ellipsometry the polarizer and the analyzer are rotated to find the searched minimum in intensity. In our variant we rotate the polarizer and the compensator instead, both being placed in the incoming beam before the substrate. Therefore the polarisation analysis of the reflected beam can be realized by an analyzer at fixed orientation. We developed this method for investigations of thin cryogenic films inside a vacuum chamber where the analyzer and detector had to be placed inside the cold shield at a temperature of T≈ 90 K close to the substrate. All other optical components were installed at the incoming beam line outside the vacuum chamber, including all components which need to be rotated during the measurements. Our null ellipsometry variant has been tested with condensed krypton films on a highly oriented pyrolytic graphite substrate (HOPG) at a temperature of T≈ 25 K. We show that it is possible to determine the indices of refraction of condensed krypton and of the HOPG substrate as well as thickness of krypton films with reasonable accuracy.

  18. The Characterization of GaAs/AlGaAs Heterostructures by Variable Angle Spectroscopic Ellipsometry

    DTIC Science & Technology

    1988-08-01

    58 E. Direct Interband Transitions in Semiconductors 68 F. MODFET and Multiple Quantum Well Energy Bands... semiconductor growth processes. Variable angle of incidence spectro- scopic ellipsometry (VASE) provides an accurate and nondestructive method of characterizing...both simple and complex multilayered semiconductor structures (2). Par- ticularly, VASE is applicable as a diagnostic tool for studying: the layer

  19. Terahertz magneto-optic generalized ellipsometry using synchrotron and blackbody radiation

    NASA Astrophysics Data System (ADS)

    Hofmann, T.; Schade, U.; Herzinger, C. M.; Esquinazi, P.; Schubert, M.

    2006-06-01

    We report on the first setup and experimental verification of terahertz frequency domain magneto-optic generalized ellipsometry using a combination of highly brilliant terahertz synchrotron and conventional blackbody radiation sources. The polarizer-sample-rotating-analyzer ellipsometry principle is employed to measure the three normalized Stokes vector elements excluding depolarization information, and the upper left 3×3 block of the normalized 4×4 Mueller matrix accordingly for wave numbers from 30to650cm-1 (0.9-20THz). We discuss setup, measurement, and data analysis procedures specific to the use of synchrotron radiation for terahertz ellipsometry. Two sample systems with different free-charge-carrier properties were studied and are presented here to illustrate terahertz ellipsometry and data analysis. The first example is low-chlorine-doped ZnMnSe, a dilute magnetic semiconductor. Analysis of the normalized Mueller matrix elements using the Drude magneto-optic dielectric function tensor model over the entire spectral range from 30to650cm-1 allowed the independent determination of the free-charge-carrier properties effective mass, concentration, and mobility. We further present and discuss Mueller matrix spectra obtained from highly oriented pyrolytic graphite at low temperatures. The spectra of this second example, a two-dimensionally confined charge carrier system, reveal distinct fingerprints of chiral electronic transitions between Landau levels.

  20. Electrically-programmable diffraction grating

    DOEpatents

    Ricco, A.J.; Butler, M.A.; Sinclair, M.B.; Senturia, S.D.

    1998-05-26

    An electrically-programmable diffraction grating is disclosed. The programmable grating includes a substrate having a plurality of electrodes formed thereon and a moveable grating element above each of the electrodes. The grating elements are electrostatically programmable to form a diffraction grating for diffracting an incident beam of light as it is reflected from the upper surfaces of the grating elements. The programmable diffraction grating, formed by a micromachining process, has applications for optical information processing (e.g. optical correlators and computers), for multiplexing and demultiplexing a plurality of light beams of different wavelengths (e.g. for optical fiber communications), and for forming spectrometers (e.g. correlation and scanning spectrometers). 14 figs.

  1. Strain and lattice orientation distribution in SiN/Ge complementary metal–oxide–semiconductor compatible light emitting microstructures by quick x-ray nano-diffraction microscopy

    SciTech Connect

    Chahine, G. A.; Schülli, T. U.; Zoellner, M. H.; Guha, S.; Reich, C.; Zaumseil, P.; Capellini, G.; Richard, M.-I.; Schroeder, T.

    2015-02-16

    This paper presents a study of the spatial distribution of strain and lattice orientation in CMOS-fabricated strained Ge microstripes using high resolution x-ray micro-diffraction. The recently developed model-free characterization tool, based on a quick scanning x-ray diffraction microscopy technique can image strain down to levels of 10{sup −5} (Δa/a) with a spatial resolution of ∼0.5 μm. Strain and lattice tilt are extracted using the strain and orientation calculation software package X-SOCS. The obtained results are compared with the biaxial strain distribution obtained by lattice parameter-sensitive μ-Raman and μ-photoluminescence measurements. The experimental data are interpreted with the help of finite element modeling of the strain relaxation dynamics in the investigated structures.

  2. Diffraction-induced coherence levels.

    PubMed

    Tavrov, Alexander; Schmit, Joanna; Kerwien, Norbert; Osten, Wolfgang; Tiziani, Hans

    2005-04-10

    We examined the influence of complex diffraction effects on low-coherence fringes created for high-aspect depth-to-width ratio structures called trenches. The coherence function was analyzed for these micrometer-wide trenches and was registered with a white-light interference microscope. For some types of surface structure we observed that additional low-coherence fringes that do not correspond directly to the surface topology are formed near the sharp edges of the structures. These additional coherence fringes were studied by rigorous numerical evaluations of vector diffractions, and these simulated interference fields were then compared with experimental results that were obtained with a white-light interference microscope.

  3. Symmetry and light stuffing of H o2T i2O7 , E r2T i2O7 , and Y b2T i2O7 characterized by synchrotron x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Baroudi, Kristen; Gaulin, Bruce D.; Lapidus, Saul H.; Gaudet, Jonathan; Cava, R. J.

    2015-07-01

    The H o2T i2O7 , E r2T i2O7 , and Y b2T i2O7 pyrochlores were studied by synchrotron x-ray diffraction to determine whether the (002) peak, forbidden in the pyrochlore space group F d -3 m but observed in single crystal neutron scattering measurements, is present due to a deviation of their pyrochlore structure from F d -3 m symmetry. Synchrotron diffraction measurements on precisely synthesized stoichiometric and nonstoichiometric powders and a crushed floating zone crystal of H o2T i2O7 revealed that the (002) reflection is absent in all cases to a sensitivity of approximately one part in 30 000 of the strongest x-ray diffraction peak. This indicates to high sensitivity that the space group of the crystal structure of these rare earth titanate pyrochlores is F d -3 m , and that, thus, the (002) peak observed in the neutron scattering experiments has a nonstructural origin. The cell parameters and internal strain for lightly stuffed H o2 +xT i2 -xO7 are also presented.

  4. Microsecond-resolved SDR-based cavity ring down ellipsometry.

    PubMed

    Sofikitis, D; Spiliotis, A K; Stamataki, K; Katsoprinakis, G E; Bougas, L; Samartzis, P C; Loppinet, B; Rakitzis, T P; Surligas, M; Papadakis, S

    2015-06-20

    We present an experimental apparatus that allows microsecond-resolved ellipsometric and absorption measurements. The apparatus is based on an optical cavity containing a Dove prism, in which light undergoes total internal reflection (TIR), while the data acquisition is based on software defined radio technology and custom-built drivers. We demonstrate the ability to sense rapid variations in the refractive index above the TIR interface for arbitrarily long times with a temporal resolution of at least 2 μs.

  5. Birefringent coherent diffraction imaging

    NASA Astrophysics Data System (ADS)

    Karpov, Dmitry; dos Santos Rolo, Tomy; Rich, Hannah; Kryuchkov, Yuriy; Kiefer, Boris; Fohtung, E.

    2016-10-01

    Directional dependence of the index of refraction contains a wealth of information about anisotropic optical properties in semiconducting and insulating materials. Here we present a novel high-resolution lens-less technique that uses birefringence as a contrast mechanism to map the index of refraction and dielectric permittivity in optically anisotropic materials. We applied this approach successfully to a liquid crystal polymer film using polarized light from helium neon laser. This approach is scalable to imaging with diffraction-limited resolution, a prospect rapidly becoming a reality in view of emergent brilliant X-ray sources. Applications of this novel imaging technique are in disruptive technologies, including novel electronic devices, in which both charge and spin carry information as in multiferroic materials and photonic materials such as light modulators and optical storage.

  6. Broadband beam shaping with harmonic diffractive optics.

    PubMed

    Singh, Manisha; Tervo, Jani; Turunen, Jari

    2014-09-22

    We consider spatial shaping of broadband (either stationary or pulsed) spatially coherent light, comparing refractive, standard diffractive, and harmonic diffractive (modulo 2πM) elements. Considering frequency-integrated target profiles we show that, contrary to common belief, standard diffractive (M = 1) elements work reasonably well for, e.g., Gaussian femtosecond pulses and spatially coherent amplified-spontaneous-emission sources such as superluminescent diodes. It is also shown that harmonic elements with M ≥ 5 behave in essentially the same way as refractive elements and clearly outperform standard diffractive elements for highly broadband light.

  7. Magneto-ellipsometry as a powerful technique for investigating magneto-optical structures properties

    NASA Astrophysics Data System (ADS)

    Maximova, Olga; Kosyrev, Nikolay; Yakovlev, Ivan; Shevtsov, Dmitriy; Lyaschenko, Sergey; Varnakov, Sergey; Ovchinnikov, Sergey

    2017-10-01

    In this work we report on new magneto-ellipsometry set-up that allows to grow thin films and nanostructures by ultrahigh vacuum thermal evaporation as well as to conduct in situ measurements during the growth in order to analyze and control nanostructures properties. Ellipsometry and transverse magneto-optical Kerr effect measurements can be performed in situ inside this set-up. A uniform magnetic field of high intensity (more than 1 kOe) can be applied to samples inside the vacuum chamber. Also, we report on the developed method of data interpretation that is the base of the set-up software. Thus, we present a powerful tool for nanostructures synthesis and characterization.

  8. Development of Calibration-Free Imaging Ellipsometry Using Dual-Rotation of Polarizer and Analyzer

    NASA Astrophysics Data System (ADS)

    Cheon, Hyuknyeong; Bak, Heung-Jin; Oh, Hyekeun; Lee, Eun-Kyu; An, Ilsin

    2007-08-01

    Imaging ellipsometry is developed in the dual-rotation mode of a polarizer and an analyzer. In this system, the polarizer and analyzer are rotated by a stepping motor at 1:1 ratio and the offset between the azimuths of both elements is kept constant. For data reduction, a two-dimensional array detector collects multiple intensity images during rotation and waveform analysis is performed for each pixel. This system generates second and fourth harmonics in intensity waveform and \\{Δ, \\Psi\\} images are deduced from the amplitudes of these harmonics without considering their phases, which leads to calibration-free imaging ellipsometry. This system works well with an offset between two elements but it becomes less susceptible to an offset-setting error with a smaller offset. Besides the ease of operation, this system is simple to construct as no complicated control mechanism is required for each component.

  9. Modeling Ellipsometry Measurements of Molecular Thin-Film Contamination on Genesis Array Samples

    NASA Technical Reports Server (NTRS)

    Calaway, Michael J.; Stansbery, E. K.; McNamara, K. M.

    2006-01-01

    The discovery of a molecular thin-film contamination on Genesis flown array samples changed the course of preliminary assessment strategies. Analytical techniques developed to measure solar wind elemental abundances must now compensate for a thin-film contamination. Currently, this is done either by experimental cleaning before analyses or by depth-profiling techniques that bypass the surface contamination. Inside Johnson Space Center s Genesis dedicated ISO Class 4 (Class 10) cleanroom laboratory, the selection of collector array fragments allocated for solar wind analyses are based on the documentation of overall surface quality, visible surface particle contamination greater than 1 m, and the amount of thin film contamination measured by spectroscopic ellipsometry. Documenting the exact thickness, surface topography, and chemical composition of these contaminates is also critical for developing accurate cleaning methods. However, the first step in characterization of the molecular film is to develop accurate ellipsometry models that will determine an accurate thickness measurement of the contamination film.

  10. Note: Grazing incidence small and wide angle x-ray scattering combined with imaging ellipsometry

    SciTech Connect

    Koerstgens, V.; Meier, R.; Ruderer, M. A.; Guo, S.; Chiang, H.-Y.; Mueller-Buschbaum, P.; Perlich, J.; Roth, S. V.; Gehrke, R.

    2012-07-15

    The combination of grazing incidence small angle x-ray scattering (GISAXS) and grazing incidence wide angle x-ray scattering (GIWAXS) with optical imaging ellipsometry is presented as an upgrade of the available measurement techniques at the wiggler beamline BW4 of the Hamburger Synchrotronstrahlungslabor. The instrument is introduced with the description of the alignment procedure to assure the measurement of imaging ellipsometry and GISAXS/GIWAXS on the same sample spot. To demonstrate the possibilities of the new instrument examples of morphological investigation on films made of poly(3-hexylthiophene) and [6,6]-phenyl-C{sub 61} butyric acid methyl ester as well as textured poly(9,9-dioctylfluorene-alt-benzo-thia-diazole) are shown.

  11. Note: Grazing incidence small and wide angle x-ray scattering combined with imaging ellipsometry

    NASA Astrophysics Data System (ADS)

    Körstgens, V.; Meier, R.; Ruderer, M. A.; Guo, S.; Chiang, H.-Y.; Perlich, J.; Roth, S. V.; Gehrke, R.; Müller-Buschbaum, P.

    2012-07-01

    The combination of grazing incidence small angle x-ray scattering (GISAXS) and grazing incidence wide angle x-ray scattering (GIWAXS) with optical imaging ellipsometry is presented as an upgrade of the available measurement techniques at the wiggler beamline BW4 of the Hamburger Synchrotronstrahlungslabor. The instrument is introduced with the description of the alignment procedure to assure the measurement of imaging ellipsometry and GISAXS/GIWAXS on the same sample spot. To demonstrate the possibilities of the new instrument examples of morphological investigation on films made of poly(3-hexylthiophene) and [6,6]-phenyl-C61 butyric acid methyl ester as well as textured poly(9,9-dioctylfluorene-alt-benzo-thia-diazole) are shown.

  12. Single shot ultrafast dynamic ellipsometry (UDE) of laser-driven shocks in single crystal explosives

    SciTech Connect

    Whitley, Von H; Mcgrane, Shawn D; Moore, David S; Eakins, Dan E; Bolme, Cindy A

    2009-01-01

    We report on the first experiments to measure states in shocked energetic single crystals with dynamic ellipsometry. We demonstrate that these ellipsometric techniques can produce reasonable Hugoniot values using small amounts of crystalline RDX and PETN. Pressures, particle velocities and shock velocities obtained using shocked ellipsometry are comparable to those found using gas-gun flyer plates and molecular dynamics calculations. The adaptation of the technique from uniform thin films of polymers to thick non-perfect crystalline materials was a significant achievement. Correct sample preparation proved to be a crucial component. Through trial and error, we were able to resolve polishing issues, sample quality problems, birefringence effects and mounting difficulties that were not encountered using thin polymer films.

  13. Multiple annular linear diffractive axicons.

    PubMed

    Bialic, Emilie; de la Tocnaye, Jean-Louis de Bougrenet

    2011-04-01

    We propose a chromatic analysis of multiple annular linear diffractive axicons. Large aperture axicons are optical devices providing achromatic nondiffracting beams, with an extended depth of focus, when illuminated by a white light source, due to chromatic foci superimposition. Annular apertures introduce chromatic foci separation, and because chromatic aberrations result in focal segment axial shifts, polychromatic imaging properties are partially lost. We investigate here various design parameters that can be used to achieve color splitting, filtering, and combining using these properties. In order to improve the low-power efficiency of a single annular axicon, we suggest a spatial multiplexing of concentric annular axicons with different sizes and periods we call multiple annular aperture diffractive axicons (MALDAs). These are chosen to maintain focal depths while enabling color imaging with sufficient diffraction efficiency. Illustrations are given for binary phase diffractive axicons, considering technical aspects such as grating design wavelength and phase dependence due to the grating thickness.

  14. Thin-film hermeticity - A quantitative analysis of diamondlike carbon using variable angle spectroscopic ellipsometry

    NASA Technical Reports Server (NTRS)

    Orzeszko, S.; De, Bhola N.; Woollam, John A.; Pouch, John J.; Alterovitz, Samuel A.

    1988-01-01

    This paper reports on the successful application of variable-angle spectroscopic ellipsometry to quantitative thin-film hermeticity evaluation. It is shown that, under a variety of film preparations and moisture introduction conditions, water penetrates only a very thin diamondlike carbon (DLC) top surface-roughness region. Thus, DLC is an excellent candidate for use as protective coatings in adverse chemical and aqueous environments.

  15. Optical investigation of reduced graphene oxide by spectroscopic ellipsometry and the band-gap tuning

    NASA Astrophysics Data System (ADS)

    Shen, Y.; Zhou, P.; Sun, Q. Q.; Wan, L.; Li, J.; Chen, L. Y.; Zhang, D. W.; Wang, X. B.

    2011-10-01

    Spectroscopic ellipsometry was used to characterize the optical response of few layer reduced graphene oxide and graphene oxide in visible range. Lorentz oscillator model is added to analyze the ellipsometric parameters. The experiment shows the optical response of few layer reduced graphene oxide and monolayer exfoliated graphene in visible range is quite similar with slight difference due to the structure defects. The Lorentz oscillator model gives experimental support to investigate the band-gap tuning through the reduction process in details.

  16. Fingerprinting ordered diffractions in multiply diffracted waves

    NASA Astrophysics Data System (ADS)

    Meles, Giovanni Angelo; Curtis, Andrew

    2014-09-01

    We show how to `fingerprint' individual diffractors inside an acoustic medium using interrogative wave energy from arrays of sources and receivers. For any recorded multiply diffracted wave observed between any source and any receiver, the set of such fingerprints is sufficient information to identify all diffractors involved in the corresponding diffraction path, and the sequential order in which diffractors are encountered. The method herein thus decomposes complex, multiply diffracted wavefields into constituent, single-diffraction interactions.

  17. Study of the Dielectric Function of Graphene from Spectroscopic Ellipsometry and Electron Energy Loss Spectroscopy

    NASA Astrophysics Data System (ADS)

    Nelson, Florence

    For more than 60 years, semiconductor research has been advancing up the periodic table. The first transistor was made from germanium. This later gave way to silicon-based devices due to the latter's ability to form an excellent interface with thermally-grown oxide. Now for the last ˜8 years, the focus has moved up one more row to carbon for post-CMOS devices in order to comply with the scaling limitations of Moore's law. However, for each of these, the measurements of film properties and dimensions have always been required for technological applications. These measurement methods often incorporate the use of light or electrons in order to take advantage of a wavelength that is on the order of, or smaller than, the feature sizes of interest. This thesis compares the dielectric function of graphene measured by an optical method to that obtained from an electron energy loss method in order to observe the effect of contamination and substrate on the optical properties of graphene exposed to the environment. Whether viewed in terms of how light affects a material (dielectric function) or how a material affects light (refractive index), the optical response is a quantity that may be used to obtain information about a film's thickness, energy structure, and the types of excitations that are responsible for energy loss. The three main experimental methods used in this thesis work are spectroscopic ellipsometry (SE), scanning transmission electron microscopy (STEM), and electron energy loss spectroscopy (EELS). SE is commonly used in clean-room environments for optical measurement over the energy range of ˜0-5 eV. This method is used to study graphene's dielectric function from the ultraviolet (UV) through infrared (IR) regions through use of an oscillator dispersion model. A nearly constant absorbance over the IR and into the visible region is observed due to vertical transitions between graphene's linearly dispersed pi-bands at the Dirac points. An exciton

  18. Structure and Thermotropic phase Behavior of Fluorinated Phospholipid Bilayers: A combined Attenuated Total Reflection FTIR Spectroscopy and Imaging Ellipsometry Study

    PubMed Central

    Schuy, Steffen; Faiss, Simon; Yoder, Nicholas C.; Kalsani, Venkateshwarlu; Kumar, Krishna; Janshoff, Andreas; Vogel, Reiner

    2008-01-01

    Lipid bilayers consisting of lipids with terminally perfluoroalkylated chains have remarkable properties. They exhibit increased stability and phase-separated nanoscale patterns in mixtures with nonfluorinated lipids. In order to understand the bilayer properties that are responsible for this behavior, we have analyzed the structure of solid-supported bilayers composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and of a DPPC analogue with 6 terminal perfluorinated methylene units (F6-DPPC). Polarized attenuated total reflection Fourier-transform infrared spectroscopy indicates that for F6-DPPC, the tilt of the lipid acyl chains to the bilayer normal is increased to 39° as compared to 21° for native DPPC, for both lipids in the gel phase. This substantial increase of the tilt angle is responsible for a decrease of the bilayer thickness from 5.4 nm for DPPC to 4.5 nm for F6-DPPC, as revealed by temperature-controlled imaging ellipsometry on microstructured lipid bilayers and solution atomic force microscopy. During the main phase transition from the gel to the fluid phase, both the relative bilayer thickness change and the relative area change are substantially smaller for F6-DPPC than for DPPC. In light of these structural and thermotropic data, we propose a model in which the higher acyl-chain tilt angle in F6-DPPC is the result of a conformational rearrangement to minimize unfavorable fluorocarbon–hydrocarbon interactions in the center of the bilayer due to chain staggering. PMID:18563929

  19. Shock induced chemistry in liquids studied with ultrafast dynamic ellipsometry and visible transient absorption spectroscopy.

    PubMed

    Dang, N C; Bolme, C A; Moore, D S; McGrane, S D

    2012-10-25

    The response to ultrafast laser shock loading of nine liquids was monitored in an effort to reveal evidence of chemical changes occurring during the first 350 ps following the shock front. In an effort to compare molecular structures possessing a variety of common bonding patterns, data were acquired for the liquids: cyclohexane, cyclohexene, 1,3-cyclohexadiene, benzene, water, acetonitrile, acrylonitrile, tert-butylacetylene, and phenylacetylene. Transient absorption spectra were measured in the spectral region from 440 to 780 nm over shock stress states from 7 to 20 GPa. Ultrafast dynamic ellipsometry was used to measure the shock and particle velocity as well as the shocked refractive index. Significant transient absorption attributed to chemical reaction was observed for shocked phenylacetylene and acrylonitrile. Evidence of volume decreasing chemical reactions was also observed in the ultrafast dynamic ellipsometry data for phenylacetylene and acrylonitrile. The liquid 1,3-cyclohexadiene exhibited volume decreasing reaction in the ultrafast dynamic ellipsometry data but did not exhibit an increase in the transient absorption spectra. There was no evidence of chemical reaction in cyclohexane, cyclohexene, benzene, water, acetonitrile, or tert-butylacetylene in the first 350 ps, despite the application of shock stress that was in many cases well above the reaction threshold observed at microsecond time scales.

  20. Ellipsometric and neutron diffraction study of pentane physisorbed on graphite.

    PubMed

    Kruchten, Frank; Knorr, Klaus; Volkmann, Ulrich G; Taub, Haskell; Hansen, Flemming Y; Matthies, Blake; Herwig, Kenneth W

    2005-08-02

    High-resolution ellipsometry and neutron diffraction measurements have been used to investigate the structure, growth, and wetting behavior of fluid pentane (n-C(5)H(12)) films adsorbed on graphite substrates. We present isotherms of the thickness of pentane films adsorbed on the basal-plane surfaces of a pyrolytic graphite substrate as a function of the vapor pressure. These isotherms are measured ellipsometrically for temperatures between 130 and 190 K. We also describe neutron diffraction measurements in the temperature range 11-140 K on a deuterated pentane (n-C(5)D(12)) monolayer adsorbed on an exfoliated graphite substrate. Below a temperature of 99 K, the diffraction patterns are consistent with a rectangular centered structure. Above the pentane triple point at 143.5 K, the ellipsometric measurements indicate layer-by-layer adsorption of at least seven fluid pentane layers, each having the same optical thickness. Analysis of the neutron diffraction pattern of a pentane monolayer at a temperature of 130 K is consistent with small clusters having a rectangular-centered structure and an area per molecule of approximately 37 A(2) in coexistence with a fluid monolayer phase. Assuming values of the polarizability tensor from the literature and that the monolayer fluid has the same areal density as that inferred for the coexisting clusters, we calculate an optical thickness of the fluid pentane layers in reasonable agreement with that measured by ellipsometry. We discuss how these results support the previously proposed "footprint reduction" mechanism of alkane monolayer melting. In the hypercritical regime, we show that the layering behavior is consistent with the two-dimensional Ising model and determine the critical temperatures for layers n = 2-5.

  1. Evaluation of Diffraction by a Rounded Surface

    NASA Technical Reports Server (NTRS)

    Rabin, Douglas M.

    2011-01-01

    Wide-angle heliospheric imagers such as those carried on the SMEI and STEREO spacecraft require highly effective baffle systems to exclude diffracted light from the solar disk as well as other sources of stray light. Buffington (2000, Appl. Opt. 39, 2683-2686) has proposed replacing multi-vane baffle systems with a curved surface that can be thought of as the limiting case of closely spaced vanes. Buffington s experimental data showed that the diffractive performance of a continuous baffle is consistent with the limiting form expected from multi-vane diffraction on dimensional grounds, but a detailed prediction was not possible because multi-vane diffraction calculations assume that the diffractive edges act independently, an assumption that breaks down for a continuous surface. I describe analytic calculations of diffraction from a smooth rounded surface based on the approach of Vogler (1985, Radio Sci. 20, 582-590).

  2. Sub-diffraction limit resolution in microscopy

    NASA Technical Reports Server (NTRS)

    Cheng, Ming (Inventor); Chen, Weinong (Inventor)

    2007-01-01

    A method and apparatus for visualizing sub-micron size particles employs a polarizing microscope wherein a focused beam of polarized light is projected onto a target, and a portion of the illuminating light is blocked from reaching the specimen, whereby to produce a shadow region, and projecting diffracted light from the target onto the shadow region.

  3. Anomalous diffraction in hyperbolic materials

    NASA Astrophysics Data System (ADS)

    Alberucci, Alessandro; Jisha, Chandroth P.; Boardman, Allan D.; Assanto, Gaetano

    2016-09-01

    We demonstrate that light is subject to anomalous (i.e., negative) diffraction when propagating in the presence of hyperbolic dispersion. We show that light propagation in hyperbolic media resembles the dynamics of a quantum particle of negative mass moving in a two-dimensional potential. The negative effective mass implies time reversal if the medium is homogeneous. Such property paves the way to diffraction compensation, i.e., spatial analog of dispersion compensating fibers in the temporal domain. At variance with materials exhibiting standard elliptic dispersion, in inhomogeneous hyperbolic materials light waves are pulled towards regions with a lower refractive index. In the presence of a Kerr-like optical response, bright (dark) solitons are supported by a negative (positive) nonlinearity.

  4. Lighting

    SciTech Connect

    Audin, L.

    1994-12-31

    EPAct covers a vast territory beyond lighting and, like all legislation, also contains numerous {open_quotes}favors,{close_quotes} compromises, and even some sleight-of-hand. Tucked away under Title XIX, for example, is an increase from 20% to 28% tax on gambling winnings, effective January 1, 1993 - apparently as a way to help pay for new spending listed elsewhere in the bill. Overall, it is a landmark piece of legislation, about a decade overdue. It remains to be seen how the Federal Government will enforce upgrading of state (or even their own) energy codes. There is no mention of funding for {open_quotes}energy police{close_quotes} in EPAct. Merely creating such a national standard, however, provides a target for those who sincerely wish to create an energy-efficient future.

  5. Diffraction from a liquid crystal phase grating.

    PubMed

    Kashnow, R A; Bigelow, J E

    1973-10-01

    The diffraction of light by a sinusoidal perturbation of the optic axis in a nematic liquid crystal is discussed. This corresponds to experiments at the electrohydrodynamic instability thresholds. An interesting qualitative feature appears: The diffraction pattern exhibits a contribution at half of the expected spatial frequency, corresponding to nonorthogonal traversals of the thick phase grating.

  6. Intensity Measurements in a Fresnel Diffraction Pattern

    ERIC Educational Resources Information Center

    Boyer, R.; Fortin, E.

    1972-01-01

    Describes an undergraduate optics laboratory experiment to verify the law of intensity in the Fesnel diffraction of a thin wire. A gas laser as light source and a photocell as detector scan the diffraction pattern. The agreement with the theoretical pattern is remarkably good. (Author/TS)

  7. Intensity Measurements in a Fresnel Diffraction Pattern

    ERIC Educational Resources Information Center

    Boyer, R.; Fortin, E.

    1972-01-01

    Describes an undergraduate optics laboratory experiment to verify the law of intensity in the Fesnel diffraction of a thin wire. A gas laser as light source and a photocell as detector scan the diffraction pattern. The agreement with the theoretical pattern is remarkably good. (Author/TS)

  8. Multilayer diffraction at 104 keV

    NASA Technical Reports Server (NTRS)

    Krieger, Allen S.; Blake, Richard L.; Siddons, D. P.

    1993-01-01

    We have measured the diffraction peak of a W:Si synthetic multilayer reflector at 104 keV using the High Energy Bonse-Hart Camera at the X-17B hard X-ray wiggler beam line of the National Synchrotron Light Source at Brookhaven National Laboratory. The characteristics of the diffraction peak are described and compared to theory.

  9. Real-Time Ellipsometry-Based Transmission Ultrasound Imaging

    SciTech Connect

    Kallman, J S; Poco, J F; Ashby, A E

    2007-02-14

    -Perot system has never been fully implemented for area imaging, and the critical angle modulation system is not sensitive enough for medical imaging. We proposed an entirely new way of using acoustic pressure to modulate a light beam. This new technology should be sensitive enough to be useful for medical imaging and have a large enough aperture to speed acquisition by orders of magnitude over point sampling. Unfortunately, we were unable to bring this technology to fruition.

  10. Diffractive Optic Fluid Shear Stress Sensor

    NASA Technical Reports Server (NTRS)

    Wilson, D.; Scalf, J.; Forouhar, S.; Muller, R.; Taugwalder, F.; Gharib, M.; Fourguette, D.; Madarress, D.

    2000-01-01

    Light scattering off particles flowing through a two-slit inteference pattern can be used to measure the shear stress of the fluid. We have designed and fabricated a miniature diffractive optic sensor based on this principle.

  11. Diffractive Optic Fluid Shear Stress Sensor

    NASA Technical Reports Server (NTRS)

    Wilson, D.; Scalf, J.; Forouhar, S.; Muller, R.; Taugwalder, F.; Gharib, M.; Fourguette, D.; Modarress, D.

    2000-01-01

    Light scattering off particles flowing through a two-slit interference pattern can be used to measure the shear stress of the fluid. We have designed and fabricated a miniature diffractive optic sensor based on this principle.

  12. Phase shifting diffraction interferometer

    DOEpatents

    Sommargren, G.E.

    1996-08-29

    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. 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. 8 figs.

  13. Phase shifting diffraction interferometer

    DOEpatents

    Sommargren, Gary E.

    1996-01-01

    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. 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.

  14. Calculation of the diffraction efficiency on concave gratings based on Fresnel-Kirchhoff's diffraction formula.

    PubMed

    Huang, Yuanshen; Li, Ting; Xu, Banglian; Hong, Ruijin; Tao, Chunxian; Ling, Jinzhong; Li, Baicheng; Zhang, Dawei; Ni, Zhengji; Zhuang, Songlin

    2013-02-10

    Fraunhofer diffraction formula cannot be applied to calculate the diffraction wave energy distribution of concave gratings like plane gratings because their grooves are distributed on a concave spherical surface. In this paper, a method based on the Kirchhoff diffraction theory is proposed to calculate the diffraction efficiency on concave gratings by considering the curvature of the whole concave spherical surface. According to this approach, each groove surface is divided into several limited small planes, on which the Kirchhoff diffraction field distribution is calculated, and then the diffraction field of whole concave grating can be obtained by superimposition. Formulas to calculate the diffraction efficiency of Rowland-type and flat-field concave gratings are deduced from practical applications. Experimental results showed strong agreement with theoretical computations. With the proposed method, light energy can be optimized to the expected diffraction wave range while implementing aberration-corrected design of concave gratings, particularly for the concave blazed gratings.

  15. Boundary diffraction wave integrals for diffraction modeling of external occulters.

    PubMed

    Cady, Eric

    2012-07-02

    An occulter is a large diffracting screen which may be flown in conjunction with a telescope to image extrasolar planets. The edge is shaped to minimize the diffracted light in a region beyond the occulter, and a telescope may be placed in this dark shadow to view an extrasolar system with the starlight removed. Errors in position, orientation, and shape of the occulter will diffract additional light into this region, and a challenge of modeling an occulter system is to accurately and quickly model these effects. We present a fast method for the calculation of electric fields following an occulter, based on the concept of the boundary diffraction wave: the 2D structure of the occulter is reduced to a 1D edge integral which directly incorporates the occulter shape, and which can be easily adjusted to include changes in occulter position and shape, as well as the effects of sources-such as exoplanets-which arrive off-axis to the occulter. The structure of a typical implementation of the algorithm is included.

  16. Spectroscopic Ellipsometry Studies of n-i-p Hydrogenated Amorphous Silicon Based Photovoltaic Devices

    PubMed Central

    Karki Gautam, Laxmi; Junda, Maxwell M.; Haneef, Hamna F.; Collins, Robert W.; Podraza, Nikolas J.

    2016-01-01

    Optimization of thin film photovoltaics (PV) relies on characterizing the optoelectronic and structural properties of each layer and correlating these properties with device performance. Growth evolution diagrams have been used to guide production of materials with good optoelectronic properties in the full hydrogenated amorphous silicon (a-Si:H) PV device configuration. The nucleation and evolution of crystallites forming from the amorphous phase were studied using in situ near-infrared to ultraviolet spectroscopic ellipsometry during growth of films prepared as a function of hydrogen to reactive gas flow ratio R = [H2]/[SiH4]. In conjunction with higher photon energy measurements, the presence and relative absorption strength of silicon-hydrogen infrared modes were measured by infrared extended ellipsometry measurements to gain insight into chemical bonding. Structural and optical models have been developed for the back reflector (BR) structure consisting of sputtered undoped zinc oxide (ZnO) on top of silver (Ag) coated glass substrates. Characterization of the free-carrier absorption properties in Ag and the ZnO + Ag interface as well as phonon modes in ZnO were also studied by spectroscopic ellipsometry. Measurements ranging from 0.04 to 5 eV were used to extract layer thicknesses, composition, and optical response in the form of complex dielectric function spectra (ε = ε1 + iε2) for Ag, ZnO, the ZnO + Ag interface, and undoped a-Si:H layer in a substrate n-i-p a-Si:H based PV device structure. PMID:28773255

  17. Combined ellipsometry and refractometry technique for characterisation of liquid crystal based nanocomposites.

    PubMed

    Warenghem, Marc; Henninot, Jean François; Blach, Jean François; Buchnev, Oleksandr; Kaczmarek, Malgosia; Stchakovsky, Michel

    2012-03-01

    Spectroscopic ellipsometry is a technique especially well suited to measure the effective optical properties of a composite material. However, as the sample is optically thick and anisotropic, this technique loses its accuracy for two reasons: anisotropy means that two parameters have to be determined (ordinary and extraordinary indices) and optically thick means a large order of interference. In that case, several dielectric functions can emerge out of the fitting procedure with a similar mean square error and no criterion to discriminate the right solution. In this paper, we develop a methodology to overcome that drawback. It combines ellipsometry with refractometry. The same sample is used in a total internal reflection (TIR) setup and in a spectroscopic ellipsometer. The number of parameters to be determined by the fitting procedure is reduced in analysing two spectra, the correct final solution is found by using the TIR results both as initial values for the parameters and as check for the final dielectric function. A prefitting routine is developed to enter the right initial values in the fitting procedure and so to approach the right solution. As an example, this methodology is used to analyse the optical properties of BaTiO(3) nanoparticles embedded in a nematic liquid crystal. Such a methodology can also be used to analyse experimentally the validity of the mixing laws, since ellipsometry gives the effective dielectric function and thus, can be compared to the dielectric function of the components of the mixture, as it is shown on the example of BaTiO(3)/nematic composite.

  18. Single Photon diffraction and interference

    NASA Astrophysics Data System (ADS)

    Hodge, John

    2015-04-01

    A previous paper based on the Scalar Theory of Everything studied photon diffraction and interference (IntellectualArchive, Vol.1, No. 3, P. 20, Toronto, Canada July 2012. http://intellectualarchive.com/?link=item&id=597). Several photons were required in the experiment at the same time. Interference experiments with one photon in the experiment at a time also showed interference patterns. The previous paper with the Bohm Interpretation, models of the screen and mask, and the Transaction Interpretation of Quantum Mechanics were combined. The reverse wave required by the Transaction Interpretation was provided by a reflected plenum wave rather than a reverse time wave. The speed of the plenum wave was assumed to be much faster than the speed of photons/light. Using the assumptions of Fraunhofer diffraction resulted in the same equation for the photon distribution on a screen as the intensity pattern of the Fraunhofer diffraction. (http://myplace.frontier.com/ ~ jchodge/)

  19. Metal island film-based structures for sensing using spectrophotometry and ellipsometry

    NASA Astrophysics Data System (ADS)

    Janicki, V.; Sancho-Parramon, J.; Bosch, S.; Zorc, H.; Belarre, F. J.; Arbiol, J.

    2014-05-01

    Metal island films (MIF) are good candidates for sensors due to the strong sensitivity of the localised surface plasmon resonance to the environment refractive index. The strong near field enhancement in the vicinity of the island surface can be even higher if a metal layer (ML) is placed close to a MIF. Structures containing MIF with and without ML are prepared and sensitivities of spectrophotometric and ellipsometric features of the measurements are compared. It is shown that simple MIF is preferable for ellipsometry-based sensing and the one including ML in the case of spectrophotometric measurements.

  20. Total internal reflection ellipsometry and SPR detection of low molecular weight environmental toxins

    NASA Astrophysics Data System (ADS)

    Nabok, A. V.; Tsargorodskaya, A.; Hassan, A. K.; Starodub, N. F.

    2005-06-01

    The environmental toxins, such as herbicides simazine and atrazine, and T2 mycotoxin were registered with the optical methods of surface plasmon resonance (SPR) and recently developed total internal reflection ellipsometry (TIRE). The immune assay approach was exploited for in situ registration of the above low molecular weight toxins with specific antibodies immobilised onto the gold surface via (poly)allylamine hydrochloride layer using electrostatic self-assembly (ESA) technique. The comparison of two methods of SPR and TIRE shows a higher sensitivity of the latter.

  1. Variable-angle ellipsometry and molecular orientation in monoclinic organic semiconductors

    NASA Astrophysics Data System (ADS)

    Tavazzi, S.; Campione, M.

    2006-02-01

    Variable-angle ellipsometry has been used to characterize oligothiophene crystals with principal axes inclined at an angle to the surface normal. The results allow deducing with high sensitivity the orientation of the molecules in these anisotropic and absorbing organic solids, thus allowing one to follow the evolution of the molecular orientation after inducing the transition of the crystallographic structure between the two polymorphs of quaterthiophene. This material is representative of a large class of solids with technological applications in either crystal or thin-film form, where different structural properties and molecular orientation may arise from different preparation conditions.

  2. Electronic and structural properties of molybdenum thin films as determined by real-time spectroscopic ellipsometry

    SciTech Connect

    Walker, J. D.; Khatri, H.; Ranjan, V.; Li Jian; Collins, R. W.; Marsillac, S.

    2009-04-06

    Real-time spectroscopic ellipsometry (RTSE) is shown to be an effective contactless probe of radio frequency magnetron sputtered molybdenum thin films used as the back electrode in chalcopyrite [Cu(In,Ga)Se{sub 2}] solar cells. A series of Mo thin films was sputtered onto soda-lime glass substrates at Ar pressures ranging from 4 to 20 mTorr. RTSE measurements reveal how Ar pressure affects the nucleation and growth mechanisms that influence the films' ultimate grain structure and properties. Determinations of the free electron relaxation times at optical frequencies reveal that higher pressures lead to a smaller average grain size and increased void volume fraction.

  3. Study of InGaAs based MODFET structures using variable angle spectroscopic ellipsometry

    NASA Technical Reports Server (NTRS)

    Alterovitz, S. A.; Sieg, R. M.; Yao, H. D.; Snyder, P. G.; Woollam, J. A.; Pamulapati, J.; Bhattacharya, P. K.; Sekula-Moise, P. A.

    1991-01-01

    Variable angle spectroscopic ellipsometry was used to estimate the thicknesses of all layers within the optical penetration depth of InGaAs based MODFET structures. Strained and unstrained InGaAs channels were made by MBE on InP substrates and by MOCVD on GaAs substrates. In most cases, ellipsometrically determined thicknesses were within 10 percent of the growth calibration results. The MBE made InGaAs strained layers showed large strain effects, indicating a probable shift in the critical points of their dielectric function toward the InP lattice matched concentration.

  4. Extracting the complex optical conductivity of mono- and bilayer graphene by ellipsometry

    NASA Astrophysics Data System (ADS)

    Chang, You-Chia; Liu, Chang-Hua; Liu, Che-Hung; Zhong, Zhaohui; Norris, Theodore B.

    2014-06-01

    A method for analysis of spectroscopic ellipsometry data is demonstrated to extract the optical conductivity of mono- and bilayer chemical-vapor-deposited graphene. We model graphene as a truly two-dimensional (2D) material with a sheet conductivity, rather than a phenomenological effective refractive index as has been used in the literature. This technique measures both the real and imaginary part of the optical conductivity, which is important for graphene optoelectronics and metamaterials. Using this method, we obtain broadband measurements of the complex optical conductivity for mono- and bilayer graphene from ultraviolet to mid-infrared wavelengths. We also study how chemical doping with nitric acid modifies the complex optical conductivity.

  5. Modeled optical properties of SiGe and Si layers compared to spectroscopic ellipsometry measurements

    NASA Astrophysics Data System (ADS)

    Kriso, C.; Triozon, F.; Delerue, C.; Schneider, L.; Abbate, F.; Nolot, E.; Rideau, D.; Niquet, Y.-M.; Mugny, G.; Tavernier, C.

    2017-03-01

    The optical response of strained SiGe alloys, as well as thin Si layers, is analyzed using a sp3d5s∗ tight-binding model within the independent particle approximation. The theoretical results are compared to measurements obtained on samples with various Ge content and layer thicknesses. The dielectric function is extracted from spectroscopic ellipsometry allowing a separation of its real and imaginary parts. Theory and simulation show similar trends for the variation of the dielectric function of SiGe with varying Ge content. Variations are also well reproduced for thin Si layers with varying thickness and are attributed to quantum confinement.

  6. Surface roughness evolution in the growth of a-Si: H thin films studied by ellipsometry

    NASA Astrophysics Data System (ADS)

    Canillas, A.; Campmany, J.; Andújar, J. L.; Bertran, E.; Morenza, J. L.

    1991-07-01

    In situ real time ellipsometry at 3.4 eV photon energy has been used to analyze the deposition of hydrogenated amorphous silicon (a-Si:H) thin films obtained by RF glow discharge decomposition of silane gas. The study is focused on the evolution of the microstructure during the films growth. The results are explained considering a theoretical model which assumes a homogeneous growth of the a-Si:H below a surface roughness layer which increases 0.5-0.7 nm in thickness during the first 400 nm of film growth. The bulk layer microstructure appears to be homogeneous within 1% of density variations.

  7. Phase-shifting point diffraction interferometer phase grating designs

    DOEpatents

    Naulleau, Patrick

    2001-01-01

    Diffraction phase gratings are employed in phase-shifting point diffraction interferometers to improve the interferometric fringe contrast. The diffraction phase grating diffracts a zeroth-order diffraction of light at a first power level to the test-beam window of a mask that is positioned at the image plane and a first-order diffraction at a second power to the reference-beam pinhole. The diffraction phase grating is preferably selected to yield a desired ratio of the first power level to second power level.

  8. Diffractive parameric colors.

    PubMed

    Orava, Joni; Heikkila, Noora; Jaaskelainen, Timo; Parkkinen, Jussi

    2008-12-01

    A method of producing inkless parameric color pairs is studied. In this method, colors are formed additively using diffraction gratings with differing grating periods as primary colors. Gratings with different grating periods reflect different spectral radiance peaks of a fluorescent lamp to the desired viewing angle, according to the grating equation. Four spectral peaks of a 4000 K fluorescent lamp--red, green, cyan, and blue-are used as the primary colors. The colors are mixed additively by fixing the relative areas of different grating periods inside a pixel. With four primary colors it is possible to mix certain colors with different triplets of primary colors. Thus, it is theoretically possible to produce metameric colors. In this study, three parameric color pairs are fabricated using electron beam lithography, electroplating, and hot embossing. The radiance spectra of the color pairs are measured by spectroradiometer from hot-embossed plastic samples. The CIELAB DeltaE(ab) and CIEDE2000 color differences between radiance spectra of the color pairs are calculated. The CIEDE2000 color differences of color pairs are between 2.6 and 7.2 units in reference viewing conditions. The effects of viewing angle and different light sources are also evaluated. It is found that both the viewing angle and the light source have very strong influences on the color differences of the color pairs.

  9. DIFFRACTION-LIMITED VISIBLE LIGHT IMAGES OF ORION TRAPEZIUM CLUSTER WITH THE MAGELLAN ADAPTIVE SECONDARY ADAPTIVE OPTICS SYSTEM (MagAO)

    SciTech Connect

    Close, L. M.; Males, J. R.; Morzinski, K.; Kopon, D.; Follette, K.; Rodigas, T. J.; Hinz, P.; Wu, Y-L.; Puglisi, A.; Esposito, S.; Riccardi, A.; Pinna, E.; Xompero, M.; Briguglio, R.; Uomoto, A; Hare, T.

    2013-09-10

    We utilized the new high-order (250-378 mode) Magellan Adaptive Optics system (MagAO) to obtain very high spatial resolution observations in ''visible light'' with MagAO's VisAO CCD camera. In the good-median seeing conditions of Magellan (0.''5-0.''7), we find MagAO delivers individual short exposure images as good as 19 mas optical resolution. Due to telescope vibrations, long exposure (60 s) r' (0.63 {mu}m) images are slightly coarser at FWHM = 23-29 mas (Strehl {approx}28%) with bright (R < 9 mag) guide stars. These are the highest resolution filled-aperture images published to date. Images of the young ({approx}1 Myr) Orion Trapezium {theta}{sup 1} Ori A, B, and C cluster members were obtained with VisAO. In particular, the 32 mas binary {theta}{sup 1} Ori C{sub 1} C{sub 2} was easily resolved in non-interferometric images for the first time. The relative positions of the bright trapezium binary stars were measured with {approx}0.6-5 mas accuracy. We are now sensitive to relative proper motions of just {approx}0.2 mas yr{sup -1} ({approx}0.4 km s{sup -1} at 414 pc)-this is a {approx}2-10 Multiplication-Sign improvement in orbital velocity accuracy compared to previous efforts. For the first time, we see clear motion of the barycenter of {theta}{sup 1} Ori B{sub 2} B{sub 3} about {theta}{sup 1} Ori B{sub 1}. All five members of the {theta}{sup 1} Ori B system appear likely to be a gravitationally bound ''mini cluster'', but we find that not all the orbits can be both circular and co-planar. The lowest mass member of the {theta}{sup 1} Ori B system (B{sub 4}; mass {approx}0.2 M{sub Sun }) has a very clearly detected motion (at 4.1 {+-} 1.3 km s{sup -1}; correlation = 99.9%) w.r.t. B{sub 1}. Previous work has suggested that B{sub 4} and B{sub 3} are on long-term unstable orbits and will be ejected from this ''mini cluster''. However, our new ''baseline'' model of the {theta}{sup 1} Ori B system suggests a more hierarchical system than previously thought, and so

  10. Single Hit Energy-resolved Laue Diffraction

    NASA Astrophysics Data System (ADS)

    Patel, Shamim; Suggit, Matthew; Stubley, Paul; Hawreliak, James; Ciricosta, Orlando; Comley, Andrew; Collins, Gilbert; Eggert, Jon; Foster, John; Wark, Justin; Higginbotham, Andrew

    2015-06-01

    In-situ white light Laue diffraction is a technique to interrogate the structure of materials undergoing dynamic compression up to megabar pressures. We present an extension to the existing Laue diffraction platform in which CCD cameras are used in single photon mode enabling a measurement of the energy of a subset of diffraction peaks. Careful choice of which diffraction peaks are observed allows for a measurement of the longitudinal and transverse strains. This allows for the measurement of absolute volume of the unit cell in addition to its aspect ratio. We present results for silicon, where only longitudinal elastic strain has been observed. VISAR measurements show the presence of a two wave structure and measurements made from the diffraction patterns on the CCD show that material downstream of the second wave does not contribute to the observed diffraction peaks, suggesting that this material may be highly disordered, or has undergone large scale rotation.

  11. Role of an Oxidant Mixture as Surface Modifier of Porous Silicon Microstructures Evaluated by Spectroscopic Ellipsometry

    PubMed Central

    Montiel-González, Zeuz; Escobar, Salvador; Nava, Rocío; del Río, J. Antonio; Tagüeña-Martínez, Julia

    2016-01-01

    Current research on porous silicon includes the construction of complex structures with luminescent and/or photonic properties. However, their preparation with both characteristics is still challenging. Recently, our group reported a possible method to achieve that by adding an oxidant mixture to the electrolyte used to produce porous silicon. This mixture can chemically modify their microstructure by changing the thickness and surface passivation of the pore walls. In this work, we prepared a series of samples (with and without oxidant mixture) and we evaluated the structural differences through their scanning electron micrographs and their optical properties determined by spectroscopic ellipsometry. The results showed that ellipsometry is sensitive to slight variations in the porous silicon structure, caused by changes in their preparation. The fitting process, based on models constructed from the features observed in the micrographs, allowed us to see that the mayor effect of the oxidant mixture is on samples of high porosity, where the surface oxidation strongly contributes to the skeleton thinning during the electrochemical etching. This suggests the existence of a porosity threshold for the action of the oxidant mixture. These results could have a significant impact on the design of complex porous silicon structures for different optoelectronic applications. PMID:27097767

  12. Role of an Oxidant Mixture as Surface Modifier of Porous Silicon Microstructures Evaluated by Spectroscopic Ellipsometry.

    PubMed

    Montiel-González, Zeuz; Escobar, Salvador; Nava, Rocío; del Río, J Antonio; Tagüeña-Martínez, Julia

    2016-04-21

    Current research on porous silicon includes the construction of complex structures with luminescent and/or photonic properties. However, their preparation with both characteristics is still challenging. Recently, our group reported a possible method to achieve that by adding an oxidant mixture to the electrolyte used to produce porous silicon. This mixture can chemically modify their microstructure by changing the thickness and surface passivation of the pore walls. In this work, we prepared a series of samples (with and without oxidant mixture) and we evaluated the structural differences through their scanning electron micrographs and their optical properties determined by spectroscopic ellipsometry. The results showed that ellipsometry is sensitive to slight variations in the porous silicon structure, caused by changes in their preparation. The fitting process, based on models constructed from the features observed in the micrographs, allowed us to see that the mayor effect of the oxidant mixture is on samples of high porosity, where the surface oxidation strongly contributes to the skeleton thinning during the electrochemical etching. This suggests the existence of a porosity threshold for the action of the oxidant mixture. These results could have a significant impact on the design of complex porous silicon structures for different optoelectronic applications.

  13. Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films.

    PubMed

    Glor, Ethan C; Fakhraai, Zahra

    2016-01-26

    This report aims to fully describe the experimental technique of using ellipsometry for cooling rate dependent Tg (CR-Tg) experiments. These measurements are simple high-throughput characterization experiments, which can determine the glass transition temperature (Tg), average dynamics, fragility and the expansion coefficient of the super-cooled liquid and glassy states for a variety of glassy materials. This technique allows for these parameters to be measured in a single experiment, while other methods must combine a variety of different techniques to investigate all of these properties. Measurements of dynamics close to Tg are particularly challenging. The advantage of cooling rate dependent Tg measurements over other methods which directly probe bulk and surface relaxation dynamics is that they are relatively quick and simple experiments, which do not utilize fluorophores or other complicated experimental techniques. Furthermore, this technique probes the average dynamics of technologically relevant thin films in temperature and relaxation time (τα) regimes relevant to the glass transition (τα > 100 sec). The limitation to using ellipsometry for cooling rate dependent Tg experiments is that it cannot probe relaxation times relevant to measurements of viscosity (τα < 1 sec). Other cooling rate dependent Tg measurement techniques, however, can extend the CR-Tg method to faster relaxation times. Furthermore, this technique can be used for any glassy system so long as the integrity of the film remains throughout the experiment.

  14. Glutathione immunosensing platform based on total internal reflection ellipsometry enhanced by functionalized gold nanoparticles.

    PubMed

    García-Marín, Antonio; Abad, José M; Ruiz, Eduardo; Lorenzo, Encarnación; Piqueras, Juan; Pau, José L

    2014-05-20

    An immunosensor to detect small molecules, such as glutathione (GSH), has been developed by combination of ellipsometry and Kretschmann surface plasmon resonance (SPR). The Au thin film used for surface plasmon polariton (SPP) excitation is functionalized with anti-GSH to specifically bind GSH. At low concentrations, the small refractive index changes caused by the low molecular weight of GSH induced only negligible shifts in the plasmon resonant energy during GSH binding. To improve sensitivity, gold nanoparticles (AuNPs) are functionalized with glutathione acting as amplifiers of the antigen-antibody interaction. Changes induced by the AuNP adsorption are monitored using Ψ and Δ ellipsometric functions. After performing competitive assays using solutions containing different concentrations of free GSH and a constant amount of functionalized AuNPs, it was concluded that the resonant energy linearly shifts as the relative concentration of free GSH increases. A detection limit for free GSH in the nanomolar range is found, demonstrating the effectiveness of AuNPs to enhance the sensitivity to immunoreactions in total internal reflection ellipsometry.

  15. High-resolution in-die metrology using beam profile reflectometry and ellipsometry

    NASA Astrophysics Data System (ADS)

    Jun, Chungsam; Park, Jangik; Opsal, Jon; Pois, Heath; Kim, In-Kyo; Kim, Jung-Wook; Nicolaides, Lena

    2007-03-01

    A new application for ultra-fast and repeatable in-die determination of CD structures at the ~1 μm length scale using BPR®/BPE® (Beam Profile Reflectometry/Ellipsometry) technologies on an Opti-Probe OP9000 series system, is presented and summarized. Two structures were measured and analyzed, including a poly-silicon CD standard and an advanced poly-silicon recessed structure relevant to advanced memory devices. A focused beam spot (~1 μm) and "fast BPR" data acquisition capability (~17 ms) were utilized to perform high-resolution scans across wafer and within single die regions. Rotating Compensator Spectroscopic Ellipsometry (RCSE®) signals were also used to independently determine and compare to BPR results from data collected over larger areas (~15 μm). The BPR/BPE and SE results for line CD were found to have high correlation. Further, model regression for SE data coupled with an artificial neural network model and fast BPR were utilized to measure and calculate 10,000 points across a 1 mm2 area in a matter of minutes. Overall, the results were found to be repeatable and correlated well to CD-SEM analysis.

  16. Fragility Nanoconfinement Effect in Thin Polymer Films: Novel Characterization by Ellipsometry

    NASA Astrophysics Data System (ADS)

    Lan, Tian; Torkelson, John

    2015-03-01

    A novel ellipsometry-based method was introduced to determine kinetic fragility in polymer films and to investigate the effect of nanoscale confinement on polymer fragility. Three systems were studied: polystyrene (PS), polycarbonate (PC), and PS doped with small molecule diluents of 1,10-bis-(1-pyrene)decane (BPD). In bulk-like films, fragility index measured by ellipsometry agreed very well with that by differential scanning calorimetry. With confinement, a dramatic decrease in fragility was observed in highly fragile PS and PC. The fragility decreased by 58% from 166 to 69 in PS and by 65% from 214 to 75 in PC as film thickness decreased from bulk to 27-28 nm; a substantially muted response was observed in the strongest of the three: PS + 2 wt% BPD, where the fragility decreased only 21% from 134 to 106 from a bulk film to a 27-nm-thick film. The larger fragility-confinement effect in more fragile polymers strongly correlates with a previous discovery of the Tg-confinement effect: the strength of the Tg-confinement effect increases with increasing fragility of bulk polymers. It indicates that bulk fragility is associated with the susceptibility of polymers to effects of nanoscale confinement.

  17. Spectroscopic ellipsometry investigations of the optical properties of manganese doped bismuth vanadate thin films

    SciTech Connect

    Kumari, Neelam; Krupanidhi, S.B.; Varma, K.B.R.

    2010-04-15

    The optical properties of Bi{sub 2}V{sub 1-x}Mn{sub x}O{sub 5.5-x} {l_brace}x = 0.05, 0.1, 0.15 and 0.2 at.%{r_brace} thin films fabricated by pulsed laser deposition on platinized silicon substrates were studied in UV-visible spectral region (1.51-4.17 eV) using spectroscopic ellipsometry. The optical constants and thicknesses of these films have been obtained by fitting the ellipsometric data ({Psi} and {Delta}) using a multilayer four-phase model system and a relaxed Lorentz oscillator dispersion relation. The surface roughness and film thickness obtained by spectroscopic ellipsometry were found to be consistent with the results obtained by atomic force and scanning electron microscopy. The refractive index measured at 650 nm does not show any marginal increase with Mn content. Further, the extinction coefficient does not show much decrease with increasing Mn content. An increase in optical band gap energy from 2.52 to 2.77 eV with increasing Mn content from x = 0.05 to 0.15 was attributed to the increase in oxygen ion vacancy disorder.

  18. In-situ spectroscopic ellipsometry study of copper selective-area atomic layer deposition on palladium

    SciTech Connect

    Jiang, Xiaoqiang; Wang, Han; Qi, Jie; Willis, Brian G.

    2014-07-01

    Selective area copper atomic layer deposition on palladium seed layers has been investigated with in-situ real-time spectroscopic ellipsometry to probe the adsorption/desorption and reaction characteristics of individual deposition cycles. The reactants are copper bis(2,2,6,6-tetramethyl-3,5-heptanedionate) vapor and hydrogen gas. Self-limiting atomic layer deposition was observed in the temperature range of 135–230 °C in a low pressure reactor. Under optimal conditions, growth occurs selectively on palladium and not on silicon dioxide or silicon nitride layers. Based on in-situ ellipsometry data and supporting experiments, a new mechanism for growth is proposed. In the proposed mechanism, precursor adsorption is reversible, and dissociatively adsorbed hydrogen are the stable surface intermediates between growth cycles. The mechanism is enabled by continuous diffusion of palladium from the seed layer into the deposited copper film and strong H* binding to palladium sites. Less intermixing can be obtained at low growth temperatures and short cycle times by minimizing Cu/Pd inter-diffusion.

  19. Role of an Oxidant Mixture as Surface Modifier of Porous Silicon Microstructures Evaluated by Spectroscopic Ellipsometry

    NASA Astrophysics Data System (ADS)

    Montiel-González, Zeuz; Escobar, Salvador; Nava, Rocío; Del Río, J. Antonio; Tagüeña-Martínez, Julia

    2016-04-01

    Current research on porous silicon includes the construction of complex structures with luminescent and/or photonic properties. However, their preparation with both characteristics is still challenging. Recently, our group reported a possible method to achieve that by adding an oxidant mixture to the electrolyte used to produce porous silicon. This mixture can chemically modify their microstructure by changing the thickness and surface passivation of the pore walls. In this work, we prepared a series of samples (with and without oxidant mixture) and we evaluated the structural differences through their scanning electron micrographs and their optical properties determined by spectroscopic ellipsometry. The results showed that ellipsometry is sensitive to slight variations in the porous silicon structure, caused by changes in their preparation. The fitting process, based on models constructed from the features observed in the micrographs, allowed us to see that the mayor effect of the oxidant mixture is on samples of high porosity, where the surface oxidation strongly contributes to the skeleton thinning during the electrochemical etching. This suggests the existence of a porosity threshold for the action of the oxidant mixture. These results could have a significant impact on the design of complex porous silicon structures for different optoelectronic applications.

  20. Study of cell-matrix adhesion dynamics using surface plasmon resonance imaging ellipsometry.

    PubMed

    Kim, Se-Hwa; Chegal, Won; Doh, Junsang; Cho, Hyun Mo; Moon, Dae Won

    2011-04-06

    The interaction of cells with extracellular matrix, termed cell-matrix adhesions, importantly governs multiple cellular phenomena. Knowledge of the functional dynamics of cell-matrix adhesion could provide critical clues for understanding biological phenomena. We developed surface plasmon resonance imaging ellipsometry (SPRIE) to provide high contrast images of the cell-matrix interface in unlabeled living cells. To improve the contrast and sensitivity, the null-type imaging ellipsometry technique was integrated with an attenuated total reflection coupler. We verified that the imaged area of SPRIE was indeed a cell-matrix adhesion area by confocal microscopy imaging. Using SPRIE, we demonstrated that three different cell types exhibit distinct features of adhesion. SPRIE was applied to diverse biological systems, including during cell division, cell migration, and cell-cell communication. We imaged the cell-matrix anchorage of mitotic cells, providing the first label-free imaging of this interaction to our knowledge. We found that cell-cell communication can alter cell-matrix adhesion, possibly providing direct experimental evidence for cell-cell communication-mediated changes in cell adhesion. We also investigated shear-stress-induced adhesion dynamics in real time. Based on these data, we expect that SPRIE will be a useful methodology for studying the role of cell-matrix adhesion in important biological phenomena.

  1. Immersion transmission ellipsometry (ITE) for the determination of orientation gradients in photoalignment layers

    NASA Astrophysics Data System (ADS)

    Jung, C. C.; Stumpe, J.

    2014-09-01

    The capability of the method of immersion transmission ellipsometry (ITE) (Jung et al. Int Patent WO, 2004/109260) to not only determine three-dimensional refractive indices in anisotropic thin films (which was already possible in the past), but even their gradients along the z-direction (perpendicular to the film plane) is investigated in this paper. It is shown that the determination of orientation gradients in deep-sub-μm films becomes possible by applying ITE in combination with reflection ellipsometry. The technique is supplemented by atomic force microscopy for measuring the film thickness. For a photo-oriented thin film, no gradient was found, as expected. For a photo-oriented film, which was subsequently annealed in a nematic liquid crystalline phase, an order was found similar to the one applied in vertically aligned nematic displays, with a tilt angle varying along the z-direction. For fresh films, gradients were only detected for the refractive index perpendicular to the film plane, as expected.

  2. Probing initial-stages of ALD growth with dynamic in situ spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Muneshwar, Triratna; Cadien, Ken

    2015-02-01

    The initial stages of ALD surface reactions are probed using dynamic in situ spectroscopic ellipsometry (d-iSE) technique during plasma-enhanced ALD of zirconium nitride (ZrN) thin films in spectral range of 0.73-6.4 eV. The measured change in the ellipsometry parameter Δ, with every precursor (TDMAZr) and reactant (forming gas plasma) exposure is interpreted as the combined effect of film growth and change in surface chemistry during ALD. We present application of Bruggeman's effective-medium approximation (B-EMA) in the analysis of d-iSE data to determine fractional surface coverage (θ) of ALD grown film at the end of every deposition cycle. During the deposition of first few ZrN monolayers, d-iSE datasets are analyzed on the basis of surface diffusion enhanced ALD growth, where the surface adsorbed precursor molecules can diffuse over substrate surface to occupy energetically favorable surface sites. The determined surface coverage of ZrN films highlights the effects of substrate enhanced ALD growth.

  3. Optical characterization of varnish films by spectroscopic ellipsometry for application in artwork conservation.

    PubMed

    Polikreti, Kyriaki; Othonos, Andreas; Christofides, Constantinos

    2005-01-01

    The specific aim of this paper is to measure the optical constants of fresh varnish layers up to a thickness of 10 mum by spectroscopic ellipsometry. It is the first time that this technique has been used in artwork conservation and it may prove very promising due to its nondestructive character. Samples of fresh dammar varnish (natural resin) and Paraloid B72 (synthetic resin) applied on glass and carbon black acrylic paint were analyzed. Both varnishes were considered as perfect dielectrics, and the real part of their refractive index was described by the Cauchy model: n (lambda) = A + B/lambda(2) + C/lambda(4). The Cauchy coefficients for dammar varnish and Paraloid B72 were then determined for layers of known thickness. The ellipsometric data were fitted to a model, which includes a mixed varnish-air layer. The optical properties of this layer were calculated by the Bruggeman effective medium approximation. In the case of carbon black acrylic paint, another mixed layer (paint-varnish) was added to the model. The results are very close to the values given in the literature. Given the measurement reproducibility, the results show that ellipsometry can discriminate between dammar varnish and Paraloid B72. This is very important in artwork conservation studies, because it has been done by time-consuming, destructive techniques up to now. Future work includes measurements of other types of natural and synthetic varnishes, in an attempt to introduce a nondestructive method for picture varnish identification and aging studies.

  4. Glass Transition of Polystyrene Thin Films on Silicon Wafer Measured by Dynamic Mechanical Analysis and Ellipsometry

    NASA Astrophysics Data System (ADS)

    Jackson, Catheryn; Lan, Tian; Caporale, Stefan; Torkelson, John

    Measuring the glass transition temperature, Tg, of polymer films in the thickness range of 20-500 nm is non-routine but commercially important for polymer films used in applications such as membranes and electronic circuit boards. Various specialized methods have been used or developed to determine Tg in thin films, including thermal ellipsometry and many others. Differential scanning calorimetry (DSC) is a more conventional method that has been used to measure Tg, but since the thin films must be scraped from the wafer, consolidation and annealing can occur in the pan and may negate effects due to film thickness. Here we report results for polystyrene (PS) spin coated on silicon wafers in the range of 20-500 nm using a benchtop dynamic mechanical analyzer (DMA) in the 3-point bending mode. For the DMA, the peak tan δ temperature is related to the polymer Tg and effects due to confinement as a function of film thickness are compared to literature values. We use thermal ellipsometry as a control method to measure film thickness and Tg in parallel. Low level additives present in commercial PS were observed to strongly affect the results for thin films and are described.

  5. Phase function design of a diffraction grating lens for an optical imaging system from a Fraunhofer diffraction perspective.

    PubMed

    Ando, Takamasa; Korenaga, Tsuguhiro; Suzuki, Masa-aki

    2013-09-10

    The potential exists to apply diffraction gratings to optical imaging systems to improve camera resolution and shorten optical length. However, we have noted the generation of striped flare lights, which differ from unnecessary-order diffraction lights, under intense lighting. We have elucidated the generation principle of these new striped lights and have discovered that they are caused by narrow diffraction grating rings. In this paper, using an analysis based on Fraunhofer diffraction, we suggest a way of minimizing them by designing an appropriate phase function structure, and test the efficacy of this design using our own manufactured prototype.

  6. X-Ray Diffraction.

    ERIC Educational Resources Information Center

    Smith, D. K.; Smith, K. L.

    1980-01-01

    Reviews applications in research and analytical characterization of compounds and materials in the field of X-ray diffraction, emphasizing new developments in applications and instrumentation in both single crystal and powder diffraction. Cites 414 references. (CS)

  7. X-ray dynamical diffraction Fraunhofer holography.

    PubMed

    Balyan, Minas

    2013-09-01

    An X-ray dynamical diffraction Fraunhofer holographic scheme is proposed. Theoretically it is shown that the reconstruction of the object image by visible light is possible. The spatial and temporal coherence requirements of the incident X-ray beam are considered. As an example, the hologram recording as well as the reconstruction by visible light of an absolutely absorbing wire are discussed.

  8. Diffraction Revisited: Position of Diffraction Spots upon Rotation of a Transmission Grating

    ERIC Educational Resources Information Center

    Vollmer, Michael

    2005-01-01

    Diffraction gratings are often used in the laboratory to determine the wavelength of laser light. What happens to the spots on the screen if the grating is rotated in this set-up? The answer is nontrivial and instructive.

  9. Diffraction Revisited: Position of Diffraction Spots upon Rotation of a Transmission Grating

    ERIC Educational Resources Information Center

    Vollmer, Michael

    2005-01-01

    Diffraction gratings are often used in the laboratory to determine the wavelength of laser light. What happens to the spots on the screen if the grating is rotated in this set-up? The answer is nontrivial and instructive.

  10. Diffraction analysis of digital micromirror device in maskless photolithography system

    NASA Astrophysics Data System (ADS)

    Xiong, Zheng; Liu, Hua; Tan, Xiangquan; Lu, Zhenwu; Li, Cuixia; Song, Liwei; Wang, Zhi

    2014-10-01

    A digital micromirror device (DMD) acts as a spatial light modulator in a maskless photolithography system. Illuminated by coherent light, DMD performs as a two-dimensional diffraction grating because of its periodical internal structure. Diffraction efficiency is an important factor for evaluating the exposure doses. A diffraction model of DMD based on Fourier analysis demonstrates that errors of the DMD's manufacture and the precision of the machining of the optical mechanical structure affect the diffraction efficiency. Additionally, analysis of exposure results by the diffraction model of DMD in Tracepro explains the degradation of the exposure quality and is helpful for calibrating the direction of optical focusing.

  11. Optical-diffraction method for determining crystal orientation

    DOEpatents

    Sopori, B.L.

    1982-05-07

    Disclosed is an optical diffraction technique for characterizing the three-dimensional orientation of a crystal sample. An arbitrary surface of the crystal sample is texture etched so as to generate a pseudo-periodic diffraction grating on the surface. A laser light beam is then directed onto the etched surface, and the reflected light forms a farfield diffraction pattern in reflection. Parameters of the diffraction pattern, such as the geometry and angular dispersion of the diffracted beam are then related to grating shape of the etched surface which is in turn related to crystal orientation. This technique may be used for examining polycrystalline silicon for use in solar cells.

  12. Improved gate process control at the 130-nm node using spectroscopic-ellipsometry-based profile metrology

    NASA Astrophysics Data System (ADS)

    Hodges, J. Scott; Lin, Yu-Lun C.; Burrows, Dale R.; Chiao, Ray H.; Peters, Robert M.; Rangarajan, Srinivasan; Bhatia, Kamal N.; Lakkapragada, Suresh

    2003-05-01

    The ability to control the cross-sectional profile of polysilicon gate structures on semiconductor devices is paramount to maximize product yield and transistor performance. Tighter control of gate profile parameters leads to a tighter distribution of transistor speeds, resulting in more optimized and consistent device performance. Furthermore, the ability to correlate physical in-line profile measurements taken at gate patterning process steps, to back-end-of-line device parametric test results, enables semiconductor manufacturers to minimize the cost per good die produced, by accurately screening out-of-spec product early in the process flow. The significant increase in the number of chips on today's 300mm wafers heightens the importance of obtaining reliable in-line data. In addition, the reduction of design rules to 130nm and below is driving precision requirements on metrology to <1nm, in order to maintain acceptable precision-to-tolerance (P/T) ratios. Historical methods of in-line metrology (Low Voltage Scanning Electron Microscopy, Atomic Force Microscopy, Electrical Critical Dimension Measurement) all face limitations with regards to precision, correlation, or throughput. This paper will demonstrate the use of Spectroscopic Ellipsometry to provide fast, accurate, and precise two-dimensional profile information on polysilicon gate structures. This metrology technique is currently being utilized for in-line process control and product disposition, at the gate lithography and etch process steps, on 130nm generation logic devices manufactured in Texas Instruments' DMOS 6 300mm wafer fabrication facility. A brief description of the measurement theory and gate profile measurement solution for both dense and isolated structures will be given. This will be followed by data generated from DMOS 6 production material. Using Spectroscopic Ellipsometry, precision results of <0.5nm for CD and height, and <0.25 degrees for profile sidewall angle were obtained at both the

  13. In-situ spectroscopic ellipsometry and structural study of HfO{sub 2} thin films deposited by radio frequency magnetron sputtering

    SciTech Connect

    Cantas, Ayten; Aygun, Gulnur; Basa, Deepak Kumar

    2014-08-28

    We have investigated the reduction of unwanted interfacial SiO{sub 2} layer at HfO{sub 2}/Si interface brought about by the deposition of thin Hf metal buffer layer on Si substrate prior to the deposition of HfO{sub 2} thin films for possible direct contact between HfO{sub 2} thin film and Si substrate, necessary for the future generation devices based on high-κ HfO{sub 2} gate dielectrics. Reactive rf magnetron sputtering system along with the attached in-situ spectroscopic ellipsometry (SE) was used to predeposit Hf metal buffer layer as well as to grow HfO{sub 2} thin films and also to undertake the in-situ characterization of the high-κ HfO{sub 2} thin films deposited on n-type 〈100〉 crystalline silicon substrate. The formation of the unwanted interfacial SiO{sub 2} layer and its reduction due to the predeposited Hf metal buffer layer as well as the depth profiling and also structure of HfO{sub 2} thin films were investigated by in-situ SE, Fourier Transform Infrared spectroscopy, and Grazing Incidence X-ray Diffraction. The study demonstrates that the predeposited Hf metal buffer layer has played a crucial role in eliminating the formation of unwanted interfacial layer and that the deposited high-κ HfO{sub 2} thin films are crystalline although they were deposited at room temperature.

  14. A high throughput approach to quantify protein adsorption on combinatorial metal/metal oxide surfaces using electron microprobe and spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Byrne, T.; Lohstreter, L.; Filiaggi, M. J.; Bai, Zhijun; Dahn, J. R.

    2008-09-01

    Although metallic biomaterials are widely used, systematic studies of protein adsorption onto such materials are generally lacking. Combinatorial binary films of Al 1-xTi x and Al 1-xNb x (0 ⩽ x ⩽ 1) and corresponding pure element films were produced on glass substrates using a unique magnetron sputtering technique. Fibrinogen and albumin adsorption amounts were measured by wavelength-dispersive spectroscopy (WDS) and spectroscopic ellipsometry (SE) equipment, both high throughput techniques with automated motion stage capabilities. X-ray diffraction revealed that the binary films have crystalline phases present near the ends of the compositional gradient with an amorphous region throughout the interior of the gradient. X-ray photoelectron spectroscopy provided the surface chemistry along the binary films and showed that Al 2O 3 preferentially formed at the surface. Protein adsorption onto these films was found to be closely correlated to the alumina surface fraction, with high alumina content at the surface leading to low amounts of adsorbed fibrinogen and albumin. Protein adsorption amounts obtained with WDS and SE were in excellent agreement for all films. This suggests that this combinatorial materials approach combined with these state-of-the-art, automated high throughput instruments provides a novel way to accurately monitor protein adsorption taking place at the surfaces of these metal/metal oxide materials.

  15. Single shot ultrafast dynamic ellipsometry of laser-driven shocks in single crystal explosives and thin films of metals

    NASA Astrophysics Data System (ADS)

    Whitley, Von; McGrane, Shawn; Moore, David; Eakins, Dan; Bolme, Cynthia

    2009-06-01

    Ultrafast dynamic ellipsometry (UDE) was used to measure the shock conditions of single-crystal energetic materials and metal thin films. Explosive crystals are coated with aluminum, which through frustrated laser ablation acts as a shock drive layer. UDE data on shocked explosives and different potential metal drive layers will be reported and experimental considerations will be discussed.

  16. Confinement effects on glass transition temperature, transition breadth, and expansivity: Comparison of ellipsometry and fluorescence measurements on polystyrene films

    NASA Astrophysics Data System (ADS)

    Kim, S.; Hewlett, S. A.; Roth, C. B.; Torkelson, J. M.

    2009-09-01

    Using ellipsometry, we characterized the nanoconfinement effect on the glass transition temperature (T gof supported polystyrene (PS) films employing two methods: the intersection of fits to the temperature (Tdependences of rubbery- and glassy-state thicknesses, and the transition mid-point between rubbery- and glassy-state expansivities. The results demonstrate a strong effect of thickness: ensuremath Tg(bulk)-Tg(23{ nm})= 10 circ C. The T -range needed for accurate measurement increases significantly with decreasing thickness, an effect that arises from the broadening of the transition with confinement and a region below T g where expansivity slowly decreases with decreasing T . As determined from expansivities, the T g breadth triples in going from bulk films to a 21-nm-thick film; this broadening of the transition may be a more dramatic effect of confinement than the T g reduction itself. In contrast, there is little effect of confinement on the rubbery- and glassy-state expansivities. Compared with ellipsometry, T g ’s from fluorescence agree well in bulk films but yield lower values in nanoconfined films: T g(bulk) - T g(23 nm) = 15° C via fluorescence. This small difference in the T g confinement effect reflects differences in how fluorescence and ellipsometry report “average T g ” with confinement. With decreasing nanoscale thickness, fluorescence may slightly overweight the contribution of the free-surface layer while ellipsometry may evenly weight or underweight its contribution. in here

  17. Diffractive corneal inlay for presbyopia.

    PubMed

    Furlan, Walter D; García-Delpech, Salvador; Udaondo, Patricia; Remón, Laura; Ferrando, Vicente; Monsoriu, Juan A

    2017-09-01

    A conceptually new type of corneal inlays for a customized treatment of presbyopia is presented. The diffractive inlay consists on a small aperture disc having an array of micro-holes distributed inside the open zones of a Fresnel zone plate. In this way, the central hole of the disc lets pass the zero order diffraction and produces an extension of the depth of far focus of the eye, while the diffracted light through the holes in the periphery produce the near focus. Additionally, the micro-holes in the inlay surface fulfill the essential requirement of allowing the flow of nutrients through it to the cells of the corneal stroma. Theoretical and optical-bench experimental results for the polychromatic axial Point Spread Function (PSF) were obtained, showing an improved performance compared to the small aperture corneal inlay currently in the market (Kamra). Images of a test object, obtained at several vergences in the surroundings of the far and near foci, are also shown. Picture: Simulation of the appearance of the Diffractive corneal inlay on a real eye. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Submicron X-ray diffraction

    SciTech Connect

    MacDowell, Alastair; Celestre, Richard; Tamura, Nobumichi; Spolenak, Ralph; Valek, Bryan; Brown, Walter; Bravman, John; Padmore, Howard; Batterman, Boris; Patel, Jamshed

    2000-08-17

    At the Advanced Light Source in Berkeley the authors have instrumented a beam line that is devoted exclusively to x-ray micro diffraction problems. By micro diffraction they mean those classes of problems in Physics and Materials Science that require x-ray beam sizes in the sub-micron range. The instrument is for instance, capable of probing a sub-micron size volume inside micron sized aluminum metal grains buried under a silicon dioxide insulating layer. The resulting Laue pattern is collected on a large area CCD detector and automatically indexed to yield the grain orientation and deviatoric (distortional) strain tensor of this sub-micron volume. A four-crystal monochromator is then inserted into the beam, which allows monochromatic light to illuminate the same part of the sample. Measurement of diffracted photon energy allows for the determination of d spacings. The combination of white and monochromatic beam measurements allow for the determination of the total strain/stress tensor (6 components) inside each sub-micron sized illuminated volume of the sample.

  19. Algorithmic methods in diffraction microscopy

    NASA Astrophysics Data System (ADS)

    Thibault, Pierre

    Recent diffraction imaging techniques use properties of coherent sources (most notably x-rays and electrons) to transfer a portion of the imaging task to computer algorithms. "Diffraction microscopy" is a method which consists in reconstructing the image of a specimen from its diffraction pattern. Because only the amplitude of a wavefield incident on a detector is measured, reconstruction of the image entails to recovering the lost phases. This extension of the 'phase problem" commonly met in crystallography is solved only if additional information is available. The main topic of this thesis is the development of algorithmic techniques in diffraction microscopy. In addition to introducing new methods, it is meant to be a review of the algorithmic aspects of the field of diffractive imaging. An overview of the scattering approximations used in the interpretation of diffraction datasets is first given, as well as a numerical propagation tool useful in conditions where known approximations fail. Concepts central to diffraction microscopy---such as oversampling---are then introduced and other similar imaging techniques described. A complete description of iterative reconstruction algorithms follows, with a special emphasis on the difference map, the algorithm used in this thesis. The formalism, based on constraint sets and projection onto these sets, is then defined and explained. Simple projections commonly used in diffraction imaging are then described. The various ways experimental realities can affect reconstruction methods will then be enumerated. Among the diverse sources of algorithmic difficulties, one finds that noise, missing data and partial coherence are typically the most important. Other related difficulties discussed are the detrimental effects of crystalline domains in a specimen, and the convergence problems occurring when the support of a complex-valued specimen is not well known. The last part of this thesis presents reconstruction results; an

  20. Ellipsometry study on gold-nanoparticle-coated gold thin film for biosensing application

    PubMed Central

    Moirangthem, Rakesh Singh; Chang, Yia-Chung; Wei, Pei-Kuen

    2011-01-01

    The amplified plasmonic response from various distributions of gold nanoparticles (AuNPs) coated on top of gold thin film was studied via ellipsometry under total internal reflection mode. The surface plasmon resonance dip can be tuned from the visible to near infrared by simply varying the AuNP concentration. Theoretical modeling based on effective medium theory with a multi-slice model has been employed to fit the experimental results. Additionally, this experimental tool has been further extended to study bio-molecular interactions with metal surfaces as well as in studying protein-protein interaction without any labeling. Hence, this technique could provide a non-destructive way of designing tunable label-free optical biosensors with very high sensitivity. PMID:21991549

  1. In situ ellipsometry of Cu surfaces immersed in benzotriazole-hydrogen peroxide solutions

    NASA Astrophysics Data System (ADS)

    Kondoh, Eiichi; Kawakami, Tatsuya; Watanabe, Mitsuhiro; Jin, Lianhua; Hamada, Satomi; Shima, Shohei; Hiyama, Hirokuni

    2016-06-01

    In the chemical mechanical polishing (CMP) of Cu, the Cu surface is oxidized and is concurrently removed by the mechanical function of an abrasive. Surface oxidation can lead to severe surface corrosion, and to prevent this, a corrosion inhibitor is added to slurries. Accurate understanding of the competition between oxidation and passivation is essential for advanced Cu CMP technologies. In this work, layer formation on clean Cu surfaces in benzotriazole (BTA), H2O2, and BTA-H2O2 aqueous solutions was studied by in situ spectroscopic ellipsometry. Time changes of ellipsometric parameters are discussed with respect to BTA and H2O2 concentrations. It was found that the BTA adsorbs onto the Cu surface and the adsorbed BTA transforms into a Cu-BTA complex in about 3 min after the onset of adsorption. The BTA/complex layer passivates the Cu surface against oxidation by H2O2.

  2. Mixed polarization in determining the film thickness of a silicon sphere by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Zhang, Ji-Tao; Wu, Xue-Jian; Li, Yan

    2012-01-01

    The effect of a spherical shape on the measurement result of spectroscopic ellipsometry (SE) is analyzed, and a method to eliminate this effect is proposed. Based on the simulation result of the SE measurement on a silicon sphere by ray tracking, we find that the sphere makes the parallel incident beam of the SE be divergent after reflection, and the measurement error of the SE caused by this phenomenon is explained by the mixed polarization theory. By settling an aperture in front of the detector of the SE, we can almost eliminate the error. For the silicon sphere with a diameter of 94 mm used in the Avogadro project, the thickness error of the oxide layer caused by the spherical shape can be reduced from 0.73 nm to 0.04 nm by using the proposed method. The principle of the method and the results of the experimental verification are presented.

  3. Spectroscopic ellipsometry study of Cu{sub 2}ZnSnSe{sub 4} bulk crystals

    SciTech Connect

    León, M. Lopez, N.; Merino, J. M.; Caballero, R.; Levcenko, S.; Gurieva, G.; Serna, R.; Bodnar, I. V.; Nateprov, A.; Guc, M.; Arushanov, E.; Schorr, S.; Perez-Rodriguez, A.

    2014-08-11

    Using spectroscopic ellipsometry we investigated and analyzed the pseudo-optical constants of Cu{sub 2}ZnSnSe{sub 4} bulk crystals, grown by the Bridgman method, over 0.8–4.5 eV photon energy range. The structures found in the spectra of the complex pseudodielectric functions were associated to E{sub 0}, E{sub 1A}, and E{sub 1B} interband transitions and were analyzed in frame of the Adachi's model. The interband transition parameters such as strength, threshold energy, and broadening were evaluated by using the simulated annealing algorithm. In addition, the pseudo-complex refractive index, extinction coefficient, absorption coefficient, and normal-incidence reflectivity were derived over 0.8–4.5 eV photon energy range.

  4. Study of targeted-treatment on colon cancer cell via spectroscopic imaging ellipsometry

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Da; Hsu, Hao Yun; Khaleel, Mai Ibrahim; Chan, Ching-Hsiang; Chang, Yia-Chung; Wu, Chien-Hsun; Wu, Han-Chung

    2017-04-01

    We present the enhancement of targeted treatment on colon cancer cell via microscopic imaging ellipsometry (MIE). All spectroscopic MIE signals on 5μm×5μm area in visible range are captured within the modified Optrel MULTISKOP system. Colon cancer cells are cultured in Bottom-up Millicell EZ SLIDE 4-well structure under the environment (37°C, 10% CO2). Original single colon cancer cell, single colon cancer cell under untargeted-treatment, and single colon cancer cell under targeted-treatment are studied by specular-reflective mode and off-specular scattering mode in this experiment. Some polarization-related and phase-related MIE images are analyzed to reveal the improvement of targeted-treatment by observing changes in specular and off-specular reflectance and absorption.

  5. Chitosan cushioned phospholipid membrane and its application in imaging ellipsometry based-biosensor

    NASA Astrophysics Data System (ADS)

    Zhang, Yibang; Chen, Yanyan; Jin, Gang

    2011-09-01

    Chitosan cushion can support the air stability of phospholipid membrane, but the problem of serum solubility of phospholipid membrane prevents it from use in serum detection applications. Poly (ethylene glycol) (PEG) shielding promises both stability and non-specific adsorption resistance for phospholipid membrane. An air stable phospholipid membrane microarray has been successfully fabricated on chitosan modified silicon wafer. We have demonstrated the potential application of PEGylated phospholipid membrane in imaging ellipsometry-based protein biosensor. Because of the strong resistance against non-specific adsorption of serum, antigens are immobilized onto the membrane surface through chemical activation and further bind their antibodies without using blocking agent. Taking advantage of the multiple and parallel reaction capabilities of microfluidic reactor system, we have assayed the binding by varying both the density of antigen on the membrane surface and the concentration of antibody in solution.

  6. Analytic determination of n, k and d of two-dimensional materials by ellipsometry and reflectivity.

    PubMed

    Adamson, Peep

    2014-07-20

    Simple diagnostics possibilities of two-dimensional absorbing materials on dielectric substrates by ellipsometry or by integrating ellipsometric and reflectance measurements are analyzed. The analysis is based on the original analytical formulas for ellipsometric angles obtained in the framework of a long-wavelength approximation. A valuable feature of this approach lies in the fact that the traditional model-based regression analysis is not used for data handling-new inversion formulas allow direct calculation of optical constants and thickness of a two-dimensional absorbing material upon a transparent substrate. In practice, it is of first importance that there exists no need of initial guesses for the desired parameters. The presented method is tested using a numerical simulation.

  7. Spectroscopic imaging ellipsometry: real-time measurement of single, intact wood pulp fibers

    NASA Astrophysics Data System (ADS)

    Ye, Chun

    2006-12-01

    A nondestructive method based on spectroscopic ellipsometry has been developed and demonstrated for the real-time measurement of a single pulp fiber's microfibril angle and phase retardation, with the latter proportional to the cell wall thickness. The method uses an optical arrangement insensitive to the sample's orientation in combination with a proper spectral analysis of the sample's image. The optical arrangement and the measurement principle of the method are described. To test the new method, equipment functioning as a spectroscopic imaging ellipsometer was constructed according to the arrangement, and measurements were carried out in which single pulp fibers and ordinary wave plates were measured. The test measurements and results are described and presented.

  8. Characterization of the SEI on a carbon film electrode by combinedEQCM and spectroscopic ellipsometry

    SciTech Connect

    evans@socrates.berkeley.edu

    2002-01-01

    The electrochemical quartz crystal microbalance (EQCM) andcyclic voltammetry have been applied simultaneously to characterizeelectron-beam deposited carbon film electrodes in LiClO4 orLiPF6-containing mixed electrolytes of ethylene carbonate (EC) anddimethyl carbonate (DMC). The structure of the carbon electrode was foundto be amorphous/disordered using Raman spectroscopy. Cyclic voltammetryin LiClO4 / EC+DMC demonstrated features typical of Liintercalation/deintercalation into/from the disordered carbon electrode,and EQCM showed a corresponding mass increase/decrease. Contrary to thecase of LiClO4 / EC+DMC electrolyte, LiPF6/EC+DMC electrolyte showed noLi deintercalation out of the thin-film carbon electrode. Combined EQCMand spectroscopic ellipsometry data were compared, and the solidelectrolyte interphase density after the first cycle in LiClO4 /EC+DMCwas estimated to be 1.3 g/cm3.

  9. Modeling the transport properties of epitaxially grown thermoelectric oxide thin films using spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Sarath Kumar, S. R.; Abutaha, Anas I.; Hedhili, M. N.; Alshareef, H. N.

    2012-01-01

    The influence of oxygen vacancies on the transport properties of epitaxial thermoelectric (Sr,La)TiO3 thin films is determined using electrical and spectroscopic ellipsometry (SE) measurements. Oxygen vacancy concentration was varied by ex-situ annealing in Ar and Ar/H2. All films exhibited degenerate semiconducting behavior, and electrical conductivity decreased (258-133 S cm-1) with increasing oxygen content. Similar decrease in the Seebeck coefficient is observed and attributed to a decrease in effective mass (7.8-3.2 me), as determined by SE. Excellent agreement between transport properties deduced from SE and direct electrical measurements suggests that SE is an effective tool for studying oxide thin film thermoelectrics.

  10. Growth of vacuum evaporated ultraporous silicon studied with spectroscopic ellipsometry and scanning electron microscopy

    NASA Astrophysics Data System (ADS)

    Kaminska, Kate; Amassian, Aram; Martinu, Ludvik; Robbie, Kevin

    2005-01-01

    Using a combination of variable-angle spectroscopic ellipsometry and scanning electron microscopy, we investigated the scaling behavior of uniaxially anisotropic, ultraporous silicon manufactured with glancing angle deposition. We found that both the diameter of the nanocolumns and the spacing between them increase with film thickness according to a power-law relationship consistent with self-affine fractal growth. An ellipsometric model is proposed to fit the optical properties of the anisotropic silicon films employing an effective medium approximation mixture of Tauc-Lorentz oscillator and void. This study shows that the optical response of silicon films made at glancing incidence differs significantly from that of amorphous silicon prepared by other methods due to highly oriented nanocolumn formation and power-law scaling.

  11. Band gap of corundumlike α -Ga2O3 determined by absorption and ellipsometry

    NASA Astrophysics Data System (ADS)

    Segura, A.; Artús, L.; Cuscó, R.; Goldhahn, R.; Feneberg, M.

    2017-07-01

    The electronic structure near the band gap of the corundumlike α phase of Ga2O3 has been investigated by means of optical absorption and spectroscopic ellipsometry measurements in the ultraviolet (UV) range (400-190 nm). The absorption coefficient in the UV region and the imaginary part of the dielectric function exhibit two prominent absorption thresholds with wide but well-defined structures at 5.6 and 6.3 eV which have been ascribed to allowed direct transitions from crystal-field split valence bands to the conduction band. Excitonic effects with large Gaussian broadening are taken into account through the Elliott-Toyozawa model, which yields an exciton binding energy of 110 meV and direct band gaps of 5.61 and 6.44 eV. The large broadening of the absorption onset is related to the slightly indirect character of the material.

  12. Structural analysis of amorphous carbon films by spectroscopic ellipsometry, RBS/ERDA, and NEXAFS

    NASA Astrophysics Data System (ADS)

    Zhou, XiaoLong; Suzuki, Tsuneo; Nakajima, Hideki; Komatsu, Keiji; Kanda, Kazuhiro; Ito, Haruhiko; Saitoh, Hidetoshi

    2017-05-01

    The structural analysis of amorphous carbon films is not only the premise of their unique properties applied in the industrial fields but also the indispensable element on their classification. In this letter, we refurbished the classification of amorphous carbon films based on the optical constants in terms of the refractive index (n) and the extinction coefficient (k). In the selected photon energy range, we defined the maximum of n (En-max) and k at a value more than 10-4 (Ek) to explore the relationship between different classification schemes for amorphous carbon films deposited by different techniques. We found that Ek and En-max of the deposited amorphous carbon films have an exponential relationship with the hydrogen contents. Thus, the spectroscopic ellipsometry analysis can also be used as one of the effective methods for the structural evaluation of the amorphous carbon films.

  13. Study of Receptor-Chaperone Interactions Using the Optical Technique of Spectroscopic Ellipsometry

    PubMed Central

    Kriechbaumer, Verena; Tsargorodskaya, Anna; Mustafa, Mohd K.; Vinogradova, Tatiana; Lacey, Joanne; Smith, David P.; Abell, Benjamin M.; Nabok, Alexei

    2011-01-01

    This work describes a detailed quantitative interaction study between the novel plastidial chaperone receptor OEP61 and isoforms of the chaperone types Hsp70 and Hsp90 using the optical method of total internal reflection ellipsometry (TIRE). The receptor OEP61 was electrostatically immobilized on a gold surface via an intermediate layer of polycations. The TIRE measurements allowed the evaluation of thickness changes in the adsorbed molecular layers as a result of chaperone binding to receptor proteins. Hsp70 chaperone isoforms but not Hsp90 were shown to be capable of binding OEP61. Dynamic TIRE measurements were carried out to evaluate the affinity constants of the above reactions and resulted in clear discrimination between specific and nonspecific binding of chaperones as well as differences in binding properties between the highly similar Hsp70 isoforms. PMID:21767504

  14. Characterization of the Refractive Index of Strained GaInNAs Layers by Spectroscopic Ellipsometry

    NASA Astrophysics Data System (ADS)

    Kitatani, Takeshi; Kondow, Masahiko; Shinoda, Kazunori; Yazawa, Yoshiaki; Okai, Makoto

    1998-03-01

    We have characterized the refractive index of strained GaInNAs layers. Using spectroscopic ellipsometry (SE), the variation in optical constants of GaInNAs layers, about 6 nm thick with a nitrogen content lower than 1%, can be clearly observed. Analysis of the SE data, including the strain effect in the layer, clarified that the refractive index of GaInNAs increases in proportion to the nitrogen content. While the trend for increase in refractive index with a decrease in the bandgap energy is the same as that observed in conventional III V alloy semiconductors, the rate of increase is found to be much larger than that in GaInAs. This result suggests a large density of states in the conduction band characteristics of this type of material system that includes nitrogen atoms.

  15. In Situ Infrared Ellipsometry for Protein Adsorption Studies on Ultrathin Smart Polymer Brushes in Aqueous Environment

    SciTech Connect

    Kroning, Annika; Furchner, Andreas; Aulich, Dennis; Bittrich, Eva; Rauch, Sebastian; Uhlmann, Petra; Eichhorn, Klaus-Jochen; Seeber, Michael; Luzinov, Igor; Kilbey, S. Michael; Lokitz, Bradley S.; Minko, Sergiy; Hinrichs, Karsten

    2015-02-10

    The protein-adsorbing and -repelling properties of various smart nanometer-thin polymer brushes with high potential for biosensing and biomedical applications are studied by in-situ infrared-spectroscopic ellipsometry (IRSE). IRSE as a highly sensitive non-destructive technique allows us to investigate protein adsorption on polymer brushes in aqueous environment in dependence of external stimuli like temperature and pH. These stimuli are, for instance, relevant in switchable mixed brushes containing poly(N-isopropyl acrylamide) and poly(acrylic acid), respectively. We use such brushes as model surfaces for controlling protein adsorption of human serum albumin and human fibrinogen. IRSE can distinguish between polymer-specific vibrational bands, which yield insights into the hydration state of the brushes, and changes in the protein-specific amide bands, which are related to changes of the protein secondary structure.

  16. Rapid, non-destructive evaluation of ultrathin WSe2 using spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Eichfeld, Sarah M.; Eichfeld, Chad M.; Lin, Yu-Chuan; Hossain, Lorraine; Robinson, Joshua A.

    2014-09-01

    The utilization of tungsten diselenide (WSe2) in electronic and optoelectronic devices depends on the ability to understand and control the process-property relationship during synthesis. We demonstrate that spectroscopic ellipsometry is an excellent technique for accurate, non-destructive determination of ultra-thin (<30 nm) WSe2 properties. The refractive index (n) and extinction coefficient (k) were found to be independent of thickness down to 1.3 nm, and were used to determine film thickness, which was confirmed to be within 9% of values found via atomic force microscopy. Finally, the optical bandgap was found to closely correlate with thickness, ranging from 1.2 to 1.55 eV as the WSe2 is thinned to the equivalent of 2 atomic layers.

  17. In Situ Infrared Ellipsometry for Protein Adsorption Studies on Ultrathin Smart Polymer Brushes in Aqueous Environment

    DOE PAGES

    Kroning, Annika; Furchner, Andreas; Aulich, Dennis; ...

    2015-02-10

    The protein-adsorbing and -repelling properties of various smart nanometer-thin polymer brushes with high potential for biosensing and biomedical applications are studied by in-situ infrared-spectroscopic ellipsometry (IRSE). IRSE as a highly sensitive non-destructive technique allows us to investigate protein adsorption on polymer brushes in aqueous environment in dependence of external stimuli like temperature and pH. These stimuli are, for instance, relevant in switchable mixed brushes containing poly(N-isopropyl acrylamide) and poly(acrylic acid), respectively. We use such brushes as model surfaces for controlling protein adsorption of human serum albumin and human fibrinogen. IRSE can distinguish between polymer-specific vibrational bands, which yield insights intomore » the hydration state of the brushes, and changes in the protein-specific amide bands, which are related to changes of the protein secondary structure.« less

  18. Nanotechnologic biosensor ellipsometry and biomarker pattern analysis in the evaluation of atherosclerotic risk profile.

    PubMed

    Siegel, G; Rodríguez, M; Sauer, F; Abletshauser, C; de Mey, C; Schötz, K; Ringstad, L; Malmsten, M; Schäfer, P

    2009-01-01

    A proteoheparan sulfate coated, hydrophobic silica surface serves as lipoprotein receptor at which the Ca(2+)-driven arteriosclerotic nanoplaque formation can be pursued by laser-based ellipsometry. Any lipoprotein from human blood can be very sensitively tested for its atherogenic properties. From the same blood sample, it is possible to determine the concentration and activity of a series of interacting biomarker molecules which, through a pattern analysis, allow to assess the state of health with respect to cardiovascular diseases. These two interlinked and complementary biosensors make a prospective cardio-cerebro-vascular risk stratification feasible, especially the sequelae of an underlying arteriosclerotic disease. Based on these diagnostic tools, an optimized therapy decision for the patient can be taken and the necessary preventive measures for the still healthy person.

  19. Rapid, non-destructive evaluation of ultrathin WSe{sub 2} using spectroscopic ellipsometry

    SciTech Connect

    Eichfeld, Sarah M.; Lin, Yu-Chuan; Hossain, Lorraine; Eichfeld, Chad M.; Robinson, Joshua A.

    2014-09-01

    The utilization of tungsten diselenide (WSe{sub 2}) in electronic and optoelectronic devices depends on the ability to understand and control the process-property relationship during synthesis. We demonstrate that spectroscopic ellipsometry is an excellent technique for accurate, non-destructive determination of ultra-thin (<30 nm) WSe{sub 2} properties. The refractive index (n) and extinction coefficient (k) were found to be independent of thickness down to 1.3 nm, and were used to determine film thickness, which was confirmed to be within 9% of values found via atomic force microscopy. Finally, the optical bandgap was found to closely correlate with thickness, ranging from 1.2 to 1.55 eV as the WSe{sub 2} is thinned to the equivalent of 2 atomic layers.

  20. Determination of the optical functions of transparent glasses by using spectroscopic ellipsometry

    SciTech Connect

    Jellison, G.E. Jr.; Sales, B.C. )

    1991-10-20

    Two-channel spectroscopic polarization-modulation ellipsometry measurements have been made on four different glasses (fused SiO{sub 2}, fine-annealed BK-7, a lead-indium-phosphate glass, and a germanium-arsenic-selenium glass). We show that this technique is sensitive to thin surface layers and that these surface layers can be modeled by using the Bruggeman effective-medium theory with 50% glass and 50% voids. By correcting the experimental spectra for these surface layers, we determined the refractive index of the sample within an error of {plus minus}0.002 in the transparent region. For wavelength regions where the material is normally opaque, the ellipsometric data can be corrected for this overlayer, thereby increasing the accuracy of the determination of both the refractive index and the extinction coefficient.

  1. Optical and Resonant X-Ray Diffraction Studies Confirm a SmC*F12-SmC* Liquid Crystal Sequence Reversal

    SciTech Connect

    Wang,S.; Liu, Z.; McCoy, B.; Pindak, R.; Caleibe, W.; Nguyen, H.; Huang, C.

    2006-01-01

    Employing both null transmission ellipsometry and resonant x-ray diffraction, we confirmed the SmC{sub F12}{sup *}-SmC* phase sequence reversal in one liquid crystal compound and specially prepared binary mixtures. This phase sequence reversal was predicted by two recent theoretical advances. Moreover, the temperature range for the SmC{sub F12}{sup *} phase increases significantly in the mixture suggesting that such a phase sequence may exist in other compounds.

  2. Expanded beam spectro-ellipsometry for big area on-line monitoring

    NASA Astrophysics Data System (ADS)

    Fried, M.; Major, C.; Juhasz, G.; Petrik, P.; Horvath, Z.

    2015-05-01

    Non-destructive analysing tools are needed at all stages of thin film process-development, especially photovoltaic (PV) development, and on production lines. In the case of thin films, layer thicknesses, micro-structure, composition, layer optical properties, and their uniformity are important parameters. An important focus is to express the dielectric functions of each component material in terms of a handful of wavelength independent parameters whose variation can cover all process variants of that material. With the resulting database, spectroscopic ellipsometry coupled with multilayer analysis can be developed for on-line point-by-point mapping and on-line line-by-line imaging. Off-line point-by-point mapping can be effective for characterization of non-uniformities in full scale PV panels or big area (even 450 mm diameter) Si-wafers in developing labs but it is slow in the on-line mode when only 15 points can be obtained (within 1 min) as a 120 cm long panel moves by the mapping station. Last years [M. Fried et al, Thin Solid Films 519, 2730 (2011)], a new instrumentation was developed that provides a line image of spectroscopic ellipsometry (wl=350- 1000 nm) data. Earlier a single 30 point line image could be collected in 10 s over a 15 cm width of PV material. Recent years we have built a 30, a 45 and a 60 cm width expanded beam ellipsometer which speed is increased by 10x. Now, 1800 points can be mapped in a 1 min traverse of a 60*120 cm PV panel or flexible roll-to-roll substrate.

  3. Spectroscopic ellipsometry for anisotropic nano-layered Al/SiO2 metamaterial with hyperbolic dispersion

    NASA Astrophysics Data System (ADS)

    Kelly, Priscilla; Martin, Andrew C.; Kuznetsova, Lyuba

    2016-09-01

    A special class of nano-layered hyperbolic metamaterials (HMMs) has received special attention recently due to their unique optical property, namely that the dispersion of the dielectric constant for HMMs exhibits a topological transition in the iso-frequency surface from an ellipsoid to a hyperboloid. Using aluminum in metal-dielectric nano-layered structures offers several advantages over currently used noble metals. The plasma frequency of the aluminum is higher than that of gold or silver. As a result, aluminum exhibits metallic characteristics over a broader spectral range than gold and silver. In addition, SiO2 is used as the dielectric for this hyperbolic metamaterial because it could be easily integrated into current CMOS technology and has near-zero losses in the UV region. In this investigation, we use generalized spectroscopic ellipsometry to study the distribution of Al within nano-layered samples fabricated using the RF sputtering technique under varying fabrication parameters with a goal of achieving hyperbolic dispersion. In our work, we developed an approach to analyzing generalized spectroscopic ellipsometry data for anisotropic Al/SiO2 structures with strong absorption, which uses the 4x4 transfer matrix approach, also known as the Berreman-formalism. This developed approach allows obtaining permittivity in all three dimensions and importing theoretical permittivity models which are tailored to the Al/SiO2 material's optical and electrical properties. In this work, we investigate the methods of reducing Al oxidation during fabrication by means of varying the fabrication temperatures and pressure by fitting data from RC2 Ellipsometer (A.C. Woollam Co.), which has dual rotating compensators. Applications for this Al/SiO2 hyperbolic metamaterial will also be discussed.

  4. Plasmonic properties of implanted Ag nanoparticles in SiO2 thin layer by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Battie, Yann; En Naciri, Aotmane; Chaoui, Nouari; Le Gall, Yann; Muller, Dominique; Carrada, Marzia; Mathiot, Daniel

    2017-08-01

    We report an uncommon study of the insertion of distributions of both volume fraction and depolarization factors in the modeling of the plasmonic properties of implanted Ag nanoparticles (Ag-NPs) in a SiO2 layer when using spectroscopic ellipsometry (SE) characterization. The Ag-NPs were embedded in the SiO2 matrix by Ag+ ion implantation at various doses of 0.5 × 1016, 1 × 1016, 2 × 1016, and 5 × 1016 ions cm-2. The formation of the Ag-NPs in a host matrix of SiO2 was controlled by transmission electron microscopy (TEM). The Ag-NPs are self-organized in the layer, and their mean radius ranges between 2 and 20 nm. The optical properties of layers were extracted by modeling the SE parameters by taking into account the depth profile concentration of Ag-NPs. The mixture of SiO2 and Ag-NP inclusions was modeled as an effective medium according to the shape distributed effective medium theory (SDEMT). In addition to the optical responses, it is shown that this model enables the explanation of the impact of NP shape distribution on the plasmon band and provides precious information about the NP shape characteristics. A good agreement was obtained between ellipsometry and TEM results. The distribution of the volume fraction in the film was found to lead to a gradient of effective dielectric function which was determined by the SDEMT model. The effective dielectric function reveals distinct Ag plasmon resonance varying as the Ag+ ions dose is varied. The real part of the dielectric function shows a significant variation around the plasmon resonance in accordance with the Kramers-Kronig equations. All determined optical parameters by SDEMT are provided and discussed. We highlight that SE combined with SDEMT calculations can be considered as a reliable tool for the determination of the NP shape and volume fraction distributions without the need of TEM.

  5. dxtbx: the diffraction experiment toolbox.

    PubMed

    Parkhurst, James M; Brewster, Aaron S; Fuentes-Montero, Luis; Waterman, David G; Hattne, Johan; Ashton, Alun W; Echols, Nathaniel; Evans, Gwyndaf; Sauter, Nicholas K; Winter, Graeme

    2014-08-01

    Data formats for recording X-ray diffraction data continue to evolve rapidly to accommodate new detector technologies developed in response to more intense light sources. Processing the data from single-crystal X-ray diffraction experiments therefore requires the ability to read, and correctly interpret, image data and metadata from a variety of instruments employing different experimental representations. Tools that have previously been developed to address this problem have been limited either by a lack of extensibility or by inconsistent treatment of image metadata. The dxtbx software package provides a consistent interface to both image data and experimental models, while supporting a completely generic user-extensible approach to reading the data files. The library is written in a mixture of C++ and Python and is distributed as part of the cctbx under an open-source licence at http://cctbx.sourceforge.net.

  6. Novel Aspects of Hard Diffraction in QCD

    SciTech Connect

    Brodsky, Stanley J.; /SLAC

    2005-12-14

    Initial- and final-state interactions from gluon-exchange, normally neglected in the parton model have a profound effect in QCD hard-scattering reactions, leading to leading-twist single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, and nuclear shadowing and antishadowing--leading-twist physics not incorporated in the light-front wavefunctions of the target computed in isolation. I also discuss the use of diffraction to materialize the Fock states of a hadronic projectile and test QCD color transparency.

  7. Chromatic confocal microscopy using staircase diffractive surface.

    PubMed

    Rayer, Mathieu; Mansfield, Daniel

    2014-08-10

    A chromatic confocal microscope (CCM) is a high-dynamic-range noncontact distance measurement sensor; it is based on a hyperchromatic lens. The vast majority of commercial CCMs use refractive-based chromatic dispersion to chromatically code the optical axis. This approach significantly limits the range of applications and performance of the CCM. In order to be a suitable alternative to a laser triangulation gauge and laser encoder, the performance of the CCM must be improved. In this paper, it is shown how hybrid aspheric diffractive (HAD) lenses can bring the CCM to its full potential by increasing the dynamic range by a factor of 2 and the resolution by a factor of 5 while passively athermizing and increasing the light throughput efficiency of the optical head [M. Rayer, U.S. patent 1122052.2 (2011)]. The only commercially suitable manufacturing process is single-point diamond turning. However, the optical power carried by the diffractive side of a hybrid aspheric diffractive lens is limited by the manufacturing process. A theoretical study of manufacturing losses has revealed that the HAD configuration with the highest diffraction efficiency is for a staircase diffractive surface (SDS). SDS lenses have the potential to reduce light losses associated with manufacturing limits by a factor of 5 without increasing surface roughness, allowing scalar diffraction-limited optical design with a diffractive element.

  8. Fiber diffraction without fibers.

    PubMed

    Poon, H-C; Schwander, P; Uddin, M; Saldin, D K

    2013-06-28

    Postprocessing of diffraction patterns of completely randomly oriented helical particles, as measured, for example, in so-called "diffract-and-destroy" experiments with an x-ray free electron laser can yield "fiber diffraction" patterns expected of fibrous bundles of the particles. This will allow "single-axis alignment" to be performed computationally, thus obviating the need to do this by experimental means such as forming fibers and laser or flow alignment. The structure of such particles may then be found by either iterative phasing methods or standard methods of fiber diffraction.

  9. Robustness of Cantor diffractals.

    PubMed

    Verma, Rupesh; Sharma, Manoj Kumar; Banerjee, Varsha; Senthilkumaran, Paramasivam

    2013-04-08

    Diffractals are electromagnetic waves diffracted by a fractal aperture. In an earlier paper, we reported an important property of Cantor diffractals, that of redundancy [R. Verma et. al., Opt. Express 20, 8250 (2012)]. In this paper, we report another important property, that of robustness. The question we address is: How much disorder in the Cantor grating can be accommodated by diffractals to continue to yield faithfully its fractal dimension and generator? This answer is of consequence in a number of physical problems involving fractal architecture.

  10. Mapping the double-slit diffraction pattern

    NASA Astrophysics Data System (ADS)

    Selvaggi, Richard; Rogers, Charles; Richardson, Clay

    2010-10-01

    A red laser, movable double-slit, movable micrometer mounted single-slit light block, and CCD were utilized to map out the single and double-slit diffraction patterns between 0 and 30 millimeters. The three dimensional mapping results demonstrate that the double-slit troughs similarly redirect the electromagnetic energy and light particles. The measured alternating path of the electromagnetic energy and light particles in the double-slit diffraction pattern is different than the theoretic path of light waves defined by destructive interference and indicates that theoretical light waves do not always have electromagnetic energy. George Monk's 1937 and Richard Feynman's 1964 finding of conservation of electromagnetic energy in the double-slit light experiment present the following questions: 1) What are the mass-less and energy-less destructive interference light waves found in the double-slit troughs? 2) What force is applied to and what energy is consumed by the work of redistributing the electromagnetic energy and light particles in the double-slit diffraction pattern? 3) Is this unknown force and unknown energy the result of dark matter found in the double-slit troughs?

  11. Phononic crystal diffraction gratings

    NASA Astrophysics Data System (ADS)

    Moiseyenko, Rayisa P.; Herbison, Sarah; Declercq, Nico F.; Laude, Vincent

    2012-02-01

    When a phononic crystal is interrogated by an external source of acoustic waves, there is necessarily a phenomenon of diffraction occurring on the external enclosing surfaces. Indeed, these external surfaces are periodic and the resulting acoustic diffraction grating has a periodicity that depends on the orientation of the phononic crystal. This work presents a combined experimental and theoretical study on the diffraction of bulk ultrasonic waves on the external surfaces of a 2D phononic crystal that consists of a triangular lattice of steel rods in a water matrix. The results of transmission experiments are compared with theoretical band structures obtained with the finite-element method. Angular spectrograms (showing frequency as a function of angle) determined from diffraction experiments are then compared with finite-element simulations of diffraction occurring on the surfaces of the crystal. The experimental results show that the diffraction that occurs on its external surfaces is highly frequency-dependent and has a definite relation with the Bloch modes of the phononic crystal. In particular, a strong influence of the presence of bandgaps and deaf bands on the diffraction efficiency is found. This observation opens perspectives for the design of efficient phononic crystal diffraction gratings.

  12. Diffraction Results from CDF

    SciTech Connect

    Goulianos, Konstantin

    2012-04-01

    We present final results by the CDF II collaboration on diffractive W and Z production, report on the status of ongoing analyses on diffractive dijet production and on rapidity gaps between jets, and briefly summarize results obtained on exclusive production pointing to their relevance to calibrating theoretical models used to predict exclusive Higgs-boson production at the LHC.

  13. Scalar Potential Model of photon diffraction

    NASA Astrophysics Data System (ADS)

    Hodge, John

    2011-04-01

    Some observations of light are inconsistent with a wave-like model. Other observations of light are inconsistent with a traditional particle-like model. A single model of light has remained a mystery. Newton's speculations, Democritus's speculations, the Bohm interpretation, and the fractal philosophy are combined with the cosmological Scalar Potential Model (SPM). The resulting model of photon structure and dynamics is tested by a toy computer experiment. The simulations included light from a distance and Young's experiment. The patterns on the screens showed diffraction wave patterns fit by the Fresnel equation. The model is consistent with the Afshar experiment and with the concepts of Bohmian mechanics.

  14. Multilayer dielectric diffraction gratings

    DOEpatents

    Perry, Michael D.; Britten, Jerald A.; Nguyen, Hoang T.; Boyd, Robert; Shore, Bruce W.

    1999-01-01

    The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described.

  15. Multilayer dielectric diffraction gratings

    DOEpatents

    Perry, M.D.; Britten, J.A.; Nguyen, H.T.; Boyd, R.; Shore, B.W.

    1999-05-25

    The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described. 7 figs.

  16. Diffraction at Hera

    NASA Astrophysics Data System (ADS)

    Collard, C.

    2003-02-01

    At the electron-proton collider HERA, diffractive interactions represent ~ 10% of the deep inelastic scattering. The production of diffractive events, characterised by the presence of a gap in rapidity or angular region without particle production, can be explained in the framework of the Regge model by the exchange of a colorless object, named the Pomeron. Describing the nature of the pomeron is a challenge for Quantum Chromodynamics. Results from the H1 and ZEUS Collaborations on exclusive vector meson production and on inclusive diffractive processes are presented.

  17. Issues in Optical Diffraction Theory

    PubMed Central

    Mielenz, Klaus D.

    2009-01-01

    This paper focuses on unresolved or poorly documented issues pertaining to Fresnel’s scalar diffraction theory and its modifications. In Sec. 2 it is pointed out that all thermal sources used in practice are finite in size and errors can result from insufficient coherence of the optical field. A quarter-wave criterion is applied to show how such errors can be avoided by placing the source at a large distance from the aperture plane, and it is found that in many cases it may be necessary to use collimated light as on the source side of a Fraunhofer experiment. If these precautions are not taken the theory of partial coherence may have to be used for the computations. In Sec. 3 it is recalled that for near-zone computations the Kirchhoff or Rayleigh-Sommerfeld integrals are applicable, but fail to correctly describe the energy flux across the aperture plane because they are not continuously differentiable with respect to the assumed geometrical field on the source side. This is remedied by formulating an improved theory in which the field on either side of a semi-reflecting screen is expressed as the superposition of mutually incoherent components which propagate in the opposite directions of the incident and reflected light. These components are defined as linear combinations of the Rayleigh-Sommerfeld integrals, so that they are rigorous solutions of the wave equation as well as continuously differentiable in the aperture plane. Algorithms for using the new theory for computing the diffraction patterns of circular apertures and slits at arbitrary distances z from either side of the aperture (down to z = ± 0.0003 λ) are presented, and numerical examples of the results are given. These results show that the incident geometrical field is modulated by diffraction before it reaches the aperture plane while the reflected field is spilled into the dark space. At distances from the aperture which are large compared to the wavelength λ these field expressions are

  18. Issues in Optical Diffraction Theory.

    PubMed

    Mielenz, Klaus D

    2009-01-01

    This paper focuses on unresolved or poorly documented issues pertaining to Fresnel's scalar diffraction theory and its modifications. In Sec. 2 it is pointed out that all thermal sources used in practice are finite in size and errors can result from insufficient coherence of the optical field. A quarter-wave criterion is applied to show how such errors can be avoided by placing the source at a large distance from the aperture plane, and it is found that in many cases it may be necessary to use collimated light as on the source side of a Fraunhofer experiment. If these precautions are not taken the theory of partial coherence may have to be used for the computations. In Sec. 3 it is recalled that for near-zone computations the Kirchhoff or Rayleigh-Sommerfeld integrals are applicable, but fail to correctly describe the energy flux across the aperture plane because they are not continuously differentiable with respect to the assumed geometrical field on the source side. This is remedied by formulating an improved theory in which the field on either side of a semi-reflecting screen is expressed as the superposition of mutually incoherent components which propagate in the opposite directions of the incident and reflected light. These components are defined as linear combinations of the Rayleigh-Sommerfeld integrals, so that they are rigorous solutions of the wave equation as well as continuously differentiable in the aperture plane. Algorithms for using the new theory for computing the diffraction patterns of circular apertures and slits at arbitrary distances z from either side of the aperture (down to z = ± 0.0003 λ) are presented, and numerical examples of the results are given. These results show that the incident geometrical field is modulated by diffraction before it reaches the aperture plane while the reflected field is spilled into the dark space. At distances from the aperture which are large compared to the wavelength λ these field expressions are reduced

  19. IN SITU Analysis Of The Growth Of Semiconductor Materials By Phase Modulated Ellipsometry From UV To IR

    NASA Astrophysics Data System (ADS)

    Drevillon, Bernard

    1990-02-01

    Examples of applications of in situ spectroscopic polarization techniques (from UV to IR) to the study of the growth of semiconductor materials are presented. The high sensitivity of these in situ diagnostics is emphasized. In particular, the ability of kinetic ellipsometry in the UV range, to study interfaces involving reactive processes like plasma deposition, with submonolayer resolution, is described. In the UV-visible range, it is shown that reflectance-difference spectroscopy (RDS) allows the real-time characterization of crystalline III-V materials and heterojunctions. In the infrared, ellipsometry appears particularly well adapted for performing detailed analysis of the vibrational properties and the growth processes of amorphous thin films. Such sensitivity to film deposition mechanisms illustrates the capacity of real-time optical diagnostics for fundamental studies and in situ control process.

  20. Thickness Dispersion of Surface Plasmon of Ag Nano-thin Films: Determination by Ellipsometry Iterated with Transmittance Method

    PubMed Central

    Gong, Junbo; Dai, Rucheng; Wang, Zhongping; Zhang, Zengming

    2015-01-01

    Effective optical constants of Ag thin films are precisely determined with effective thickness simultaneously by using an ellipsometry iterated with transmittance method. Unlike the bulk optical constants in Palik's database the effective optical constants of ultrathin Ag films are found to strongly depend on the thickness. According to the optical data two branches of thickness dispersion of surface plasmon energy are derived and agreed with theoretical predication. The thickness dispersion of bulk plasmon is also observed. The influence of substrate on surface plasmon is verified for the first time by using ellipsometry. The thickness dependent effective energy loss function is thus obtained based on this optical method for Ag ultrathin films. This method is also applicable to other ultrathin films and can be used to establish an effective optical database for ultrathin films. PMID:25797217

  1. Thickness Dispersion of Surface Plasmon of Ag Nano-thin Films: Determination by Ellipsometry Iterated with Transmittance Method

    NASA Astrophysics Data System (ADS)

    Gong, Junbo; Dai, Rucheng; Wang, Zhongping; Zhang, Zengming

    2015-03-01

    Effective optical constants of Ag thin films are precisely determined with effective thickness simultaneously by using an ellipsometry iterated with transmittance method. Unlike the bulk optical constants in Palik's database the effective optical constants of ultrathin Ag films are found to strongly depend on the thickness. According to the optical data two branches of thickness dispersion of surface plasmon energy are derived and agreed with theoretical predication. The thickness dispersion of bulk plasmon is also observed. The influence of substrate on surface plasmon is verified for the first time by using ellipsometry. The thickness dependent effective energy loss function is thus obtained based on this optical method for Ag ultrathin films. This method is also applicable to other ultrathin films and can be used to establish an effective optical database for ultrathin films.

  2. Spurious electro-optic coefficients inferred from modulation ellipsometry measurements in the presence of an air cavity

    NASA Astrophysics Data System (ADS)

    Quilty, J. W.

    2017-04-01

    This paper describes how thin air gaps in multilayer polymer thin film structures can lead to unexpectedly large signals in modulation ellipsometry experiments, which can then be misinterpreted as the electro-optic effect. The contributions from the electro-optic effect and polarisation on reflection from the air cavity are indistinguishable and the reflection contribution can be on the order of 100 times that of the electro-optic effect. Caution must thus be exercised in any attempt to measure electro-optic coefficients with modulation ellipsometry in the presence of air gaps, to avoid spuriously high results. Thin film multilayer structures containing air gaps may be suitable for some of the same applications as electro-optic reflectance modulators.

  3. Zeno dynamics in wave-packet diffraction spreading

    SciTech Connect

    Porras, Miguel A.; Luis, Alfredo; Gonzalo, Isabel; Sanz, Angel S.

    2011-11-15

    We analyze a simple and feasible practical scheme displaying Zeno, anti-Zeno, and inverse-Zeno effects in the observation of wave-packet spreading caused by free evolution. The scheme is valid both in spatial diffraction of classical optical waves and in time diffraction of a quantum wave packet. In the optical realization, diffraction spreading is observed by placing slits between a light source and a light-power detector. We show that the occurrence of Zeno or anti-Zeno effects depends just on the frequency of observations between the source and detector. These effects are seen to be related to the diffraction mode theory in Fabry-Perot resonators.

  4. Flatland optics. III. Achromatic diffraction.

    PubMed

    Lohmann, A W; Pe'er, A; Wang, D; Friesem, A A

    2001-09-01

    In the previous two sections of "Flatland optics" [J. Opt. Soc. Am. A 17, 1755 (2000); 18, 1056 (2001)] we described the basic principles of two-dimensional (2D) optics and showed that a wavelength lambda in three-dimensional (3D) space (x, y, z) may appear in Flatland (x, z) as a wave with another wavelength Lambda=lambda/cos alpha. The tilt angle alpha can be modified by a 3D-Spaceland individual, who then is able to influence the 2D optics in a way that must appear to be magical to 2D-Flatland individuals-in the spirit of E. A. Abbott's science fiction story of 1884 [Flatland, a Romance of Many Dimensions, 6th ed. (Dover, New York, 1952)]. Here we show how the light from a white source can be perceived in Flatland as perfectly monochromatic, so diffraction with white light will be free of color blurring and the contrast of interference fringes can be 100%. The basic considerations for perfectly achromatic diffraction are presented, along with experimental illustration of Talbot self-imaging performed with broadband illumination.

  5. Coherent Diffractive Imaging at LCLS

    NASA Astrophysics Data System (ADS)

    Schulz, Joachim

    2010-03-01

    Soft x-ray FEL light sources produce ultrafast x-ray pulses with outstanding high peak brilliance. This might enable the structure determination of proteins that cannot be crystallized. The deposited energy would destroy the molecules completely, but owing to the short pulses the destruction will ideally only happen after the termination of the pulse. In order to address the many challenges that we face in attempting molecular diffraction, we have carried out experiments in coherent diffraction from protein nanocrystals at the Linac Coherent Light Source (LCLS) at SLAC. The periodicity of these objects gives us much higher scattering signals than uncrystallized proteins would. The crystals are filtered to sizes less than 2 micron, and delivered to the pulsed X-ray beam in a liquid jet. The effects of pulse duration and fluence on the high-resolution structure of the crystals have been studied. Diffraction patterns are recorded at a repetition rate of 30 Hz with pnCCD detectors. This allows us to take 108,000 images per hour. With 2-mega-pixel-detectors this gives a data-rate of more than 400 GB per hour. The automated sorting and evaluation of hundreds of thousands images is another challenge of this kind of experiments. Preliminary results will be presented on our first LCLS experiments. This work was carried out as part of a collaboration, for which Henry Chapman is the spokesperson. The collaboration consists of CFEL DESY, Arizona State University, SLAC, Uppsala University, LLNL, The University of Melbourne, LBNL, the Max Planck Institute for Medical Research, and the Max Planck Advanced Study Group (ASG) at the CFEL. The experiments were carried out using the CAMP apparatus, which was designed and built by the Max Planck ASG at CFEL. The LCLS is operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences.

  6. Low Temprature Growth of Silicon Dioxide Films: A Study of Chemical Bonding by Ellipsometry and Infrared Spectroscopy.

    DTIC Science & Technology

    1986-07-29

    City , State and ZIP CodeI 7b. ADDRESS ( City , State and ZIP Code) 11-3 Venable Hall 045A Chemistry Program Chapel Hill, NC 27514 800 N. Quincy Street...SUB GR 19 A %STRACT ’Contlinue on reerse if necessary and identify b) biock nmirber; 2 :-his paper presents a spectroscopic study using the techniques...Chapel Hill NC 27514 ABSTRACT This paper presents a spectroscopic study using the techniques of ellipsometry and infrared (ir) absorption spectroscopy of

  7. Fresnel Coherent Diffractive Imaging

    SciTech Connect

    Williams, G. J.; Quiney, H. M.; Dhal, B. B.; Tran, C. Q.; Nugent, K. A.; Peele, A. G.; Paterson, D.; Jonge, M. D. de

    2006-07-14

    We present an x-ray coherent diffractive imaging experiment utilizing a nonplanar incident wave and demonstrate success by reconstructing a nonperiodic gold sample at 24 nm resolution. Favorable effects of the curved beam illumination are identified.

  8. Fraunhofer Diffraction and Polarization.

    ERIC Educational Resources Information Center

    Fortin, E.

    1979-01-01

    Describes an experiment for the intermediate undergraduate optics laboratory designed to illustrate simultaneously some aspects of the phenomena of diffraction; interference, coherence, apodization, the Fresnel-Arago law; as well as of the interrelations between these concepts. (HM)

  9. Diffraction with CMS

    SciTech Connect

    Pereira, Antonio Vilela

    2011-07-15

    The observation of diffraction at LHC with the CMS detector at {radical}(s) = 900 and 2360 GeV is presented, along with a comparison of the data with the predictions of the PYTHIA and PHOJET generators.

  10. Mueller matrix ellipsometry studies of the optical phonons and crystal field excitations in multiferroic orthoferrites RFeO3 (R=Tb,Dy)

    NASA Astrophysics Data System (ADS)

    Martinez, V. A.; Stanislavchuk, T. N.; Sirenko, A. A.; Litvinchuk, A. P.; Wang, Yazhong; Cheong, S. W.

    Optical properties of multiferroic orthoferrites RFeO3 (R=Tb,Dy) bulk crystals have been studied in the far-infrared range from 50 to 1000 cm-1 and temperatures from 7 K to 300 K. Mueller matrix and rotating analyzer ellipsometry measurements were carried out at the U4IR beamline of the National Synchrotron Light Source at Brookhaven National Lab. Optical phonon spectra and crystal field excitations were measured for all three orthorhombic axes of RFeO3. In the experimental temperature dependencies of the phonon frequencies we found non-Grüneisen behavior caused by the electron-phonon and spin-phonon interactions. We determined the symmetries and selection rules for the crystal field transitions in Tb3+ and Dy3+ ions. Magnetic field dependencies of the optical spectra allowed us to determine anisotropy of the crystal field g-factors for Tb3+ and Dy3+ ions. This Project is supported by collaborative DOE Grant DE-FG02-07ER46382 between Rutgers U. and NJIT. Use of NSLS-BNL was supported by DOE DE-AC02-98CH10886. V.A. Martinez was supported by NEU NSF-1343716.

  11. Complex Refractive Index Spectra of CH3NH3PbI3 Perovskite Thin Films Determined by Spectroscopic Ellipsometry and Spectrophotometry.

    PubMed

    Löper, Philipp; Stuckelberger, Michael; Niesen, Bjoern; Werner, Jérémie; Filipič, Miha; Moon, Soo-Jin; Yum, Jun-Ho; Topič, Marko; De Wolf, Stefaan; Ballif, Christophe

    2015-01-02

    The complex refractive index (dielectric function) of planar CH3NH3PbI3 thin films at room temperature is investigated by variable angle spectroscopic ellipsometry and spectrophotometry. Knowledge of the complex refractive index is essential for designing photonic devices based on CH3NH3PbI3 thin films such as solar cells, light-emitting diodes, or lasers. Because the directly measured quantities (reflectance, transmittance, and ellipsometric spectra) are inherently affected by multiple reflections, the complex refractive index has to be determined indirectly by fitting a model dielectric function to the experimental spectra. We model the dielectric function according to the Forouhi-Bloomer formulation with oscillators positioned at 1.597, 2.418, and 3.392 eV and achieve excellent agreement with the experimental spectra. Our results agree well with previously reported data of the absorption coefficient and are consistent with Kramers-Kronig transformations. The real part of the refractive index assumes a value of 2.611 at 633 nm, implying that CH3NH3PbI3-based solar cells are ideally suited for the top cell in monolithic silicon-based tandem solar cells.

  12. Residual Stress Relaxation and Stiffness-Confinement Effects in Polymer Films: Characterization by Non-Contact Ellipsometry and Fluorescence Techniques

    NASA Astrophysics Data System (ADS)

    Askar, Shadid; Torkelson, John

    2015-03-01

    The relaxation of residual stresses in spin-coated polymer films is characterized using two optical techniques: ellipsometry and fluorescence. Both techniques show that residual stresses relax over hours at several tens of degrees above the film glass transition temperature (Tg). Ellipsometry shows that thickness can increase or decrease during residual stress relaxation depending on thermal history of the film. However, the presence or relaxation of stresses has no measurable effect on Tg as measured by ellipsometry. We have adapted the well-known sensitivity of the pyrene dye fluorescence spectral shape to local environment polarity in order to characterize stress relaxation and to monitor stiffness-confinement effects. The spectral shape of the pyrene fluorescence spectrum shows similar stress relaxation regardless of whether relaxation is accompanied by increases or decreases in film thickness. Fluorescence also indicates that single-layer polystyrene films supported on silica stiffen with decreasing nanoscale thickness. For the first time, stiffness gradients as a function of distance from interfaces are demonstrated using pyrene label fluorescence in conjunction with multilayer films.

  13. In situ optical characterizations of the annealing effects upon SnO2:F films by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Yuan, Guangzhong; Wang, Kangkai; Li, Ming; Gao, Qian; Liu, Yong; Jia, Shaohui; Song, Chenlu; Han, Gaorong

    2016-10-01

    In situ study of the annealing effects, up to 600 °C, upon the optical performance of SnO2:F films have been successfully conducted with spectroscopic ellipsometry. The thickness and optical parameters were obtained by the regression of the measured ellipsometry parameters using a five-layer model. The results show that the re-densification of the SnO2:F layers occurs at above 200 °C, resulting in an irreversible thickness reducing from about 326 nm to about 321 nm. The refractive index of the SnO2:F layer increases with temperature and decreases in the cooling period. The in situ temperature dependence of the average refractive index has a good agreement with the sheet resistance measurement results, not only verifying the annealing process deteriorates the low-emissivity performance, but also demonstrates that spectroscopic ellipsometry method is a suitable optical characterization technique to adjust the on-line coating process of float glass.

  14. Combined atomic force microscopy and spectroscopic ellipsometry applied to the analysis of lipid-protein thin films.

    PubMed

    Finot, Eric; Markey, Laurent; Hane, Francis; Amrein, Mathias; Leonenko, Zoya

    2013-04-01

    Pulmonary surfactant is a complex mixture of phospholipids and proteins and forms a thin film at the lung alveolar interface separating air from liquid environment. The film reduces the work of breathing during repeatable compressions of the alveoli which form a characteristic multilayer upon compression. In this work, we investigated the structure of bovine lipid extract surfactant (BLES). We analysed the BLES films by atomic force microscopy (AFM) and spectroscopic ellipsometry (SE) in order to provide combined characterization of both morphology and thickness of surfactant films. We show how the spectroscopic ellipsometry can be used to supplement the data obtained by AFM. We demonstrate that indium tin oxide (ITO) substrate used for spectroscopic ellipsometry is preferable over glass substrate to enhance the optical contrast. An optical model was proposed to account for non-uniform film morphology. We obtained good correlations between the multilayer surface coverage, determined by both AFM and SE. SE measures the thickness of the first uniform monolayer as 2.6 nm that cannot be achieved by AFM imaging alone.

  15. Diffraction as tunneling

    NASA Technical Reports Server (NTRS)

    Nussenzveig, H. M.; Wiscombe, W. J.

    1987-01-01

    A new approximation to the short-wavelength scattering amplitude from an impenetrable sphere is presented. It is uniform in the scattering angle and it is more accurate than previously known approximations (including Fock's theory of diffraction) by up to several orders of magnitude. It remains valid in the transition to long-wavelength scattering. It leads to a new physical picture of diffraction, as tunneling through an inertial barrier.

  16. Polarizing binary diffraction grating beam splitter.

    PubMed

    Davis, Jeffrey A; Evans, Garrett H

    2004-07-01

    We report a polarizing beam splitter that uses binary phase gratings written onto a liquid-crystal spatial light modulator. These gratings produce several linearly polarized diffracted orders and a zeroth-order beam whose polarization state can be completely controlled. Experimental results are shown.

  17. In Situ Infrared Ellipsometry for Protein Adsorption Studies on Ultrathin Smart Polymer Brushes in Aqueous Environment.

    PubMed

    Kroning, Annika; Furchner, Andreas; Aulich, Dennis; Bittrich, Eva; Rauch, Sebastian; Uhlmann, Petra; Eichhorn, Klaus-Jochen; Seeber, Michael; Luzinov, Igor; Kilbey, S Michael; Lokitz, Bradley S; Minko, Sergiy; Hinrichs, Karsten

    2015-06-17

    The protein-adsorbing and -repelling properties of various smart nanometer-thin polymer brushes containing poly(N-isopropylacrylamide) and poly(acrylic acid) with high potential for biosensing and biomedical applications are studied by in situ infrared-spectroscopic ellipsometry (IRSE). IRSE is a highly sensitive nondestructive technique that allows protein adsorption on polymer brushes to be investigated in an aqueous environment as external stimuli, such as temperature and pH, are varied. These changes are relevant to conditions for regulation of protein adsorption and desorption for biotechnology, biocatalysis, and bioanalytical applications. Here brushes are used as model surfaces for controlling protein adsorption of human serum albumin and human fibrinogen. The important finding of this work is that IRSE in the in situ experiments in protein solutions can distinguish between contributions of polymer brushes and proteins. The vibrational bands of the polymers provide insights into the hydration state of the brushes, whereas the protein-specific amide bands are related to changes of the protein secondary structure.

  18. Fast IR laser mapping ellipsometry for the study of functional organic thin films.

    PubMed

    Furchner, Andreas; Sun, Guoguang; Ketelsen, Helge; Rappich, Jörg; Hinrichs, Karsten

    2015-03-21

    Fast infrared mapping with sub-millimeter lateral resolution as well as time-resolved infrared studies of kinetic processes of functional organic thin films require a new generation of infrared ellipsometers. We present a novel laboratory-based infrared (IR) laser mapping ellipsometer, in which a laser is coupled to a variable-angle rotating analyzer ellipsometer. Compared to conventional Fourier-transform infrared (FT-IR) ellipsometers, the IR laser ellipsometer provides ten- to hundredfold shorter measurement times down to 80 ms per measured spot, as well as about tenfold increased lateral resolution of 120 μm, thus enabling mapping of small sample areas with thin-film sensitivity. The ellipsometer, equipped with a HeNe laser emitting at about 2949 cm(-1), was applied for the optical characterization of inhomogeneous poly(3-hexylthiophene) [P3HT] and poly(N-isopropylacrylamide) [PNIPAAm] organic thin films used for opto-electronics and bioapplications. With the constant development of tunable IR laser sources, laser-based infrared ellipsometry is a promising technique for fast in-depth mapping characterization of thin films and blends.

  19. Silicon fin line edge roughness determination and sensitivity analysis by Mueller matrix spectroscopic ellipsometry based scatterometry

    NASA Astrophysics Data System (ADS)

    Dixit, Dhairya; O'Mullane, Samuel; Sunkoju, Sravan; Hosler, Erik R.; Kamineni, Vimal; Preil, Moshe; Keller, Nick; Race, Joseph; Muthinti, Gangadhara Raja; Diebold, Alain C.

    2015-03-01

    Measurement and control of line edge roughness (LER) is one of the most challenging issues facing patterning technology. As the critical dimensions (CD) of patterned structures decrease, LER of only a few nanometers can negatively impact device performance. Here, Mueller matrix spectroscopic ellipsometry (MMSE) based scatterometry is used to determine LER in periodic line-space structures in 28 nm pitch Si fin samples fabricated by directed selfassembly (DSA) patterning. The optical response of the Mueller matrix (MM) elements is influenced by structural parameters like pitch, CD, height, and side-wall angle (SWA), as well as the optical properties of the materials. Evaluation and decoupling MM element response to LER from other structural parameters requires sensitivity analysis using simulations of optical models that include LER. Here, an approach is developed that quantifies Si fin LER by comparing the optical responses generated by systematically varying the grating shape and measurement conditions. Finally, the validity of this approach is established by comparing the results obtained from top down scanning electron microscope (SEM) images and cross-sectional TEM image of the 28 nm pitch Si fins.

  20. The electrochemical behaviour of copper in alkaline solutions containing fluoride, studied by in situ ellipsometry

    NASA Astrophysics Data System (ADS)

    Berlouis, L. E. A.; Mamman, D. A.; Azpuru, I. G.

    1998-06-01

    In situ ellipsometry has been used to reveal a number of interesting features in the growth of passivating films on Cu in 0.1 M KOH containing KF. Fluoride ions are shown to affect the growth of the oxide layer and enhanced dissolution of copper as the Cu II species occurs as a result of stress corrosion cracking. A restructuring of the oxide film within the passive region is attributed to loss of water and this effect becomes less distinct with increasing F - ion concentration in the electrolyte and disorder in the oxide layer. The enhanced reduction of the conductively inhibited bulk CuO/Cu(OH) 2 layer back to copper found in alkaline solutions containing fluoride would indicate that the formation of this layer is the dominant one for passivation of copper in this medium. The difference between the start and the end Δ- Ψ values of the metal surface of the cyclic voltammogram at -1.5 V versus SCE indicates either roughening arising from the oxide formation/reduction or the presence of a residual surface oxide.

  1. Adsorption from black tea and red wine onto in vitro salivary pellicles studied by ellipsometry.

    PubMed

    Joiner, Andrew; Muller, Dries; Elofsson, Ulla M; Malmsten, Martin; Arnebrant, Thomas

    2003-10-01

    The adsorption of black tea and red wine components onto a pellicle-like protein layer formed in vitro by adsorption from whole unstimulated saliva on hydroxyapatite discs were studied by in situ ellipsometry. It was found that components from black tea readily adsorbed to the pellicle. Subsequent exposure to saliva led to further adsorption of salivary components to give an overall increase in the amounts adsorbed. The amounts adsorbed increased still further following a third tea and saliva exposure. Components of red wine gave significantly greater amounts of adsorption to the pellicle than black tea. The adsorption of components of black tea gave a concomitant increase in colour or stain as measured by a reflectance chromameter. In all cases, the black tea- and red wine-modified pellicles were not eluted by either phosphate buffer or sodium dodecyl sulphate (SDS) rinses. Thus, black tea and red wine components have been shown to have a profound effect on in vitro pellicle maturation, causing thickened layers of stained material to build up, which are not readily removed.

  2. Probing the carrier concentration profiles in phosphorus-implanted germanium using infrared spectroscopic ellipsometry

    SciTech Connect

    D'Costa, Vijay Richard Yeo, Yee-Chia

    2015-02-21

    Spectroscopic ellipsometry with photon energy in the 0.045–0.65 eV range was used to investigate germanium samples implanted with 30 keV phosphorus ions and annealed at 700 °C. The infrared response of implanted layers is dominated by free carrier absorption which is modeled using a Drude oscillator. The carrier concentration profiles were modeled using an error function, and compared with those obtained by electrochemical capacitance-voltage profiling and secondary ion mass spectrometry. In the flat region of the carrier concentration profile, average carrier concentration and mobility of 1.40 × 10{sup 19} cm{sup −3} and 336 cm{sup 2}V{sup −1}s{sup −1}, respectively, were obtained. A phosphorus diffusivity of ∼1.2 × 10{sup −13} cm{sup 2}/s was obtained. The mobility versus carrier concentration relationships obtained for the implanted samples are close to the empirical relationship for bulk Ge.

  3. Optical model for spectroscopic ellipsometry analysis of plasma-induced damage to SiOC films

    NASA Astrophysics Data System (ADS)

    Nishida, Kentaro; Ono, Kouichi; Eriguchi, Koji

    2017-06-01

    We propose a new optical model for assigning the physical structure of plasma-damaged SiOC films examined by spectroscopic ellipsometry. A two-parameter Bruggeman’s effective medium approximation is used for estimating the thickness and volume fraction of a low-dielectric (ɛ) region (ɛ ˜ 1) in the SiO2 background. We introduced an optical model consisting of damaged and undamaged layers. The thickness and fraction of the damaged layer are fitted. Prediction was performed using this model for SiOC samples exposed to various plasmas, and the results were compared with those of scanning electron microscopy. We further applied this model to estimating the depth of damaged region in combination with a layer-by-layer wet-etching technique. In the case of He plasma exposure, the structural change induced by the damage extends 90-130 nm in depth. Since the degradation of interlayer dielectrics affects the circuit performance, the proposed optical model should be used for designing plasma processes.

  4. In situ spectroscopic ellipsometry during electrochemical treatment of zinc in alkaline carbonate electrolyte

    NASA Astrophysics Data System (ADS)

    Chen, Ying; Erbe, Andreas

    2013-01-01

    In situ spectroscopic ellipsometry (SE, 297-820 nm, 4.4-1.5 eV) during electrochemical oxidation/reduction of zinc in alkaline carbonate electrolyte was performed using a specially designed optical-electrochemical cell. The growth and shrinkage of the interfacial layer on Zn was analysed on the basis of Lekner's first order perturbation theory. For non-absorbing thin films on metal surfaces, an algorithm has been derived to extract the thickness of a surface film directly from ellipsometric data without the need of optical modelling. During cyclic voltammetry (CV), a rapid decrease/increase in the layer thickness in the reduction/oxidation peak has been found. In the potential regime where the surface is oxide-covered, the layer thickness increases/decreases linearly with potential in anodic/cathodic scans. The density of the interfacial region in this regime is constant. During chronoamperometric experiments, a fast correlating jump in thickness was found after potential jumps. An ageing of the films is observed in the absorption spectrum (from the ellipsometric parameter Ψ), which shows changes until ≈ 30 min after potential jumps. Analysis of the current transients points to continuous dissolution of Zn.

  5. Spectroscopic ellipsometry as a process control tool for manufacturing cadmium telluride thin film photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Smith, Westcott P.

    In recent decades, there has been concern regarding the sustainability of fossil fuels. One of the more promising alternatives is Cadmium Telluride (CdTe) thin-film photovoltaic (PV) devices. Improved quality measurement techniques may aid in improving this existing technology. Spectroscopic ellipsometry (SE) is a common, non-destructive technique for measuring thin films in the silicon wafer industry. SE results have also been tied to properties believed to play a role in CdTe PV device efficiency. A study assessing the potential of SE for use as a quality measurement tool had not been previously reported. Samples of CdTe devices produced by both laboratory and industrial scale processes were measured by SE and Scanning Electron Microscopy (SEM). Mathematical models of the optical characteristics of the devices were developed and fit to SE data from multiple angles and locations on each sample. Basic statistical analysis was performed on results from the automated fits to provide an initial evaluation of SE as a quantitative quality measurement process. In all cases studied, automated SE models produced average stack thickness values within 10% of the values produced by SEM, and standard deviations for the top bulk layer thickness were less than 1% of the average values.

  6. Optical properties of a nanostructured glass-based film using spectroscopic ellipsometry

    DOE PAGES

    Jellison, G. E.; Aytug, T.; Lupini, A. R.; ...

    2015-12-22

    Nanostructured glass films, which are fabricated using spinodally phase-separated low-alkali glasses, have several interesting and useful characteristics, including being robust, non-wetting and antireflective. Spectroscopic ellipsometry measurements have been performed on one such film and its optical properties were analyzed using a 5-layer structural model of the near-surface region. Since the glass and the film are transparent over the spectral region of the measurement, the Sellmeier model is used to parameterize the dispersion in the refractive index. To simulate the variation of the optical properties of the film over the spot size of the ellipsometer (~ 3 × 5 mm), themore » Sellmeier amplitude is convoluted using a Gaussian distribution. The transition layers between the ambient and the film and between the film and the substrate are modeled as graded layers, where the refractive index varies as a function of depth. These layers are modeled using a two-component Bruggeman effective medium approximation where the two components are the layer above and the layer below. Lastly, the fraction is continuous through the transition layer and is modelled using the incomplete beta function.« less

  7. Optical properties of a nanostructured glass-based film using spectroscopic ellipsometry

    SciTech Connect

    Jellison, G. E.; Aytug, T.; Lupini, A. R.; Paranthaman, M. P.; Joshi, Pooran C.

    2015-12-22

    Nanostructured glass films, which are fabricated using spinodally phase-separated low-alkali glasses, have several interesting and useful characteristics, including being robust, non-wetting and antireflective. Spectroscopic ellipsometry measurements have been performed on one such film and its optical properties were analyzed using a 5-layer structural model of the near-surface region. Since the glass and the film are transparent over the spectral region of the measurement, the Sellmeier model is used to parameterize the dispersion in the refractive index. To simulate the variation of the optical properties of the film over the spot size of the ellipsometer (~ 3 × 5 mm), the Sellmeier amplitude is convoluted using a Gaussian distribution. The transition layers between the ambient and the film and between the film and the substrate are modeled as graded layers, where the refractive index varies as a function of depth. These layers are modeled using a two-component Bruggeman effective medium approximation where the two components are the layer above and the layer below. Lastly, the fraction is continuous through the transition layer and is modelled using the incomplete beta function.

  8. High temperature phase transitions and critical exponents of Samarium orthoferrite determined by in situ optical ellipsometry

    NASA Astrophysics Data System (ADS)

    Berini, B.; Fouchet, A.; Popova, E.; Scola, J.; Dumont, Y.; Franco, N.; da Silva, R. M. C.; Keller, N.

    2012-03-01

    Determining phase transitions has always been a great challenge in material science due to their important fundamental and technological aspects. Recently, iron-based perovskites (RFeO3), exhibiting phase transitions at high temperatures, have attracted much interest for their functional properties at room temperature, such as multiferroicity (BiFeO3) and ultrafast spin dynamics (TmFeO3). In this family of materials, Samarium orthoferrite (SmFeO3) is a weak ferromagnet, ordering at high temperatures and exhibiting an intrinsic spin reorientation transition above room temperature, which is "hidden" in macroscopic magnetization measurements in polycrystalline samples. In the present article, we show that the related magnetic high temperature phase transitions can be studied through their dielectric functions by spectroscopic ellipsometry in situ and without any need for an applied external magnetic field. The presence of this intrinsic spin reorientation transition is demonstrated for textured SmFeO3 films and we have determined a critical exponent of β = 0.45 ± 0.01 for the magnetic phase transition, coherently from optical, magneto-optical, and structural investigations.

  9. New method for determination of the photoresist Dill parameters using spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Boher, Pierre; Defranoux, Christophe; Piel, Jean-Philippe; Stehle, Jean-Louis P.

    1999-04-01

    In this paper a new method to determine photoresist Dill parameters is presented. Based on spectroscopic ellipsometry (SE) measurements, this new method is more precise than standard techniques based on transmittance measurements. Indeed, compared to photometry, SE technique is a self calibrated technique which provide directly two independent parameters Tan (Psi) and Cos (Delta) which can be used to extract directly thickness but also optical indices of a layer inside a multilayer structure. Moreover, the wavelength dependence introduces more restrictions for the data analysis since thickness and optical indices can be deduced directly in many cases. We apply this technique to different kinds of photoresist designed for 365nm and 248nm. At each wavelength ellipsometric parameters are simulated directly versus the exposure dose without any assumption on the thickness and on the index of refraction evolution. On 365nm photoresist this new method provides Dill parameters in good agreement with the standard method. On 248nm photoresist we show that the influence of the exposure is more important on the refractive index and on the thickness of the layer than on its absorption.

  10. New method for determination of the photoresist Dill parameters using spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Boher, Pierre; Defranoux, Christophe; Piel, Jean-Philippe; Stehle, Jean-Louis P.

    1999-06-01

    In this paper a new method to determine photoresist DIll parameters is presented. Based on spectroscopic ellipsometry (SE) measurements, this new method is more precise than standard techniques based on transmittance measurements. Indeed, compared to photometry, SE technique is a self calibrated technique which provide directly two independent parameters Tan (Psi) and Cos (Delta) which can be used to extract directly thickness but also optical indices of a layer inside a multilayer structure. Moreover, the wavelength dependence introduces more restrictions for the data analysis since thickness and optical indices can be deduced directly in many cases. We apply this technique to different kinds of photoresist designed for 365nm and 248nm. At each wavelength ellipsometric parameters are simulate directly versus the exposure dose without any assumption on the thickness and on the index of refraction evolution. On 365nm photoresist this new method provides Dill parameters in good agreement with the standard method. On 248nm photoresist we show that the influence of the exposure is more important on the refractive index and on the thickness of the layer than on its absorption.

  11. Diblock copolymer adsorption onto a solid surface as revealed by evanescent wave ellipsometry

    SciTech Connect

    Kim, M.W. ); Russell, T.P. . Almaden Research Center); Moses, T.; Chen, W.; Shen, Y.R. . Center for Advanced Materials Univ. of California, Berkeley, CA . Dept. of Physics)

    1994-12-05

    The interfacial behavior of diblock copolymers play an important role in many practical applications, for example, polymer compatibilization, adhesion, and colloid stabilization. There has been considerable theoretical and experimental effort to understand the adsorption behavior of diblock copolymers from a solution onto a solid surface. Recent neutron reflectivity measurements on solutions of symmetric diblock copolymers of polystyrene and poly(methyl methacrylate), denoted P(S-b-MMA), near a quartz wall have shown that the PMMA segments adsorb preferentially onto the quartz forming a dense layer. However, the segmental concentration of polystyrene (PS) was too low to be observable. Evanescent wave ellipsometry, EWE, on the other hand, allows one to determine the density of molecules adsorbed onto a surface without labeling the segments with deuterium. Here, EWE results on P(S-b-MMA) adsorbed onto a solid substrate are presented as a function of molecular weight. It is shown that the adsorbed amount of copolymer is maximized for a particular molecular weight. This result contradicts theoretical predictions, and a possible origin of this discrepancy is provided.

  12. Spectroscopic ellipsometry study of N+ ion-implanted ethylene-norbornene films

    NASA Astrophysics Data System (ADS)

    Šiljegović, M.; Kačarević-Popović, Z. M.; Stchakovsky, M.; Radosavljević, A. N.; Korica, S.; Novaković, M.; Popović, M.

    2014-05-01

    The optical properties of 150 keV N+ implanted ethylene-norbornene (TOPAS 6017S-04) copolymer were investigated using phase modulated spectroscopic ellipsometry (PMSE) and ultraviolet-visible (UV-Vis) spectroscopy in the ranges of 0.6-6.5 eV and of 1.5-6.2 eV, respectively. The single-effective-oscillator model was used to fit the calculated data to the experimental ellipsometric spectra. The results show that the oscillator and dispersion energies decrease with increasing ion fluence up to 1015 cm-2, and then these parameters increase with further fluence increasing. Analysis of the UV-Vis absorption spectra revealed the presence of indirect electronic transitions with the band gap energy in the range of 1.3 to 2.8 eV. It was found that both the band gap energy and the energy width of the distribution of localized band tail states decrease, while the values of Tauc coefficient increase with increasing the ion fluence. From the ellipsometric data we found that the real part of the dielectric function increased about 7% after irradiation with 1015 cm-2, and decreased about 10% in samples modified with 1016 cm-2.

  13. Ultrafast chemical reactions in shocked nitromethane probed with dynamic ellipsometry and transient absorption spectroscopy.

    PubMed

    Brown, Kathryn E; McGrane, Shawn D; Bolme, Cynthia A; Moore, David S

    2014-04-10

    Initiation of the shock driven chemical reactions and detonation of nitromethane (NM) can be sensitized by the addition of a weak base; however, the chemical mechanism by which sensitization occurs remains unclear. We investigated the shock driven chemical reaction in NM and in NM sensitized with diethylenetriamine (DETA), using a sustained 300 ps shock driven by a chirped Ti:sapphire laser. We measured the solutions' visible transient absorption spectra and measured interface particle and shock velocities of the nitromethane solutions using ultrafast dynamic ellipsometry. We found there to be a volume-increasing reaction that takes place around interface particle velocity up = 2.4 km/s and up = 2.2 km/s for neat NM and NM with 5% DETA, respectively. The rate at which transient absorption increases is similar in all mixtures, but with decreasing induction times for solutions with increasing DETA concentrations. This result supports the hypothesis that the chemical reaction mechanisms for shocked NM and NM with DETA are the same. Data from shocked NM are compared to literature experimental and theoretical data.

  14. Vanadium oxide-carbon nanotube composite films characterized by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    He, Qiong; Xu, Xiangdong; Gu, Yu; Wang, Meng; Yao, Jie; Jiang, Yadong; Sun, Minghui; Ao, Tianhong; Lian, Yuxiang; Wang, Fu; Li, Xinrong

    2016-10-01

    Spectroscopic ellipsometry (SE) is utilized to characterize the vanadium oxide (VO x )-single walled carbon nanotube (SWCNT) composite films prepared by sol-gel. Five Tauc-Lorentz oscillators model is employed to describe the dispersions in the optical responses of VO x and VO x -SWCNT thin films. Results reveal that if the SWCNT concentration in the composite film is increased, the refractive index is decreased, while the extinction coefficient is increased. Moreover, higher SWCNT content leads to lower optical band gap (E g) but larger localized state (E e). Interestingly, both E g and E e values reach saturated at a SWCNT content of ~8 wt%. Particularly, the peak transition energies of the 5 Tauc-Lorentz oscillators have been assigned to the specific transitions according to the band structures of VO x . This work reveals the feasibility of investigating the optical properties and microstructures of VO x -SWCNT composite films by SE. These experimental results will be helpful for better understanding the VO x -SWCNT composite films, and promoting future characterizations of other SWCNT-based composites by SE.

  15. Magneto-optical coupling in ferromagnetic thin films investigated by vector-magneto-optical generalized ellipsometry

    NASA Astrophysics Data System (ADS)

    Mok, K.; Kovács, G. J.; McCord, J.; Li, L.; Helm, M.; Schmidt, H.

    2011-09-01

    We performed generalized Mueller matrix ellipsometry measurements in a magnetic field of arbitrary orientation and magnitude up to 400 mT at room temperature and probed the magneto-optical response of capped, ferromagnetic Fe, Ni20Fe80, Co, Ni80Fe20, and Ni thin films on ZnO substrates in the spectral range from 300 to 1100 nm. We determined the off-diagonal elements in the magneto-optical dielectric tensor under saturated magnetization conditions in the sample surface plane via a model analysis. The off-diagonal elements depend on the net spin polarization and the electronic band structure of the ferromagnetic thin films. For the pure ferromagnetic metals Fe, Co, and Ni, the converted off-diagonal elements agree well with the reported experimental optical conductivity data. As a result we use the extracted wavelength-dependent magneto-optical coupling constant to predict the wavelength-dependent magneto-optical response of different Ni/Fe multilayer structures.

  16. Strontium titanate (100) surfaces monitoring by high temperature in situ ellipsometry

    NASA Astrophysics Data System (ADS)

    Hrabovsky, D.; Berini, B.; Fouchet, A.; Aureau, D.; Keller, N.; Etcheberry, A.; Dumont, Y.

    2016-03-01

    We report monitoring and analysis of the contamination overlayer on the surface of different SrTiO3 (STO) substrates by in situ spectroscopic ellipsometry (SE) and ex situ X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Substrates of STO with different terminations, random and TiO2 terminated, were heated from room temperature up to 720 °C under oxygen pressure in UHV chamber similar to conditions commonly used for epitaxial growth of perovskite oxides. Contamination layer on the substrate was modeled as an equivalent dielectric overlayer with a thickness of 2 nm at room temperature which decreases progressively during the heating up to reach its minimum (around 1 unit cell) at the temperature around 550 °C. After exposition to air, surface recovers a contamination layer on both types of substrates (with random termination and TiO2 termination). XPS analysis confirmed that water and carbon dioxide as adventitious carbon species present in air are chemically adsorbed on the STO surface, providing evidence of desorption process which persists until 550 °C. This condition is an important issue in order to obtain clean controlled interface between STO and deposited film for low temperature growth as for instance atomic layer deposition and integration of STO buffer layer on silicon. In situ SE commonly present in thin layer deposition systems is a powerful tool to monitor in situ surface contamination and decontamination temperature as it can be performed in situ even in operando.

  17. Glass transition in thin supported polystyrene films probed by temperature-modulated ellipsometry in vacuum.

    PubMed

    Efremov, Mikhail Yu; Kiyanova, Anna V; Last, Julie; Soofi, Shauheen S; Thode, Christopher; Nealey, Paul F

    2012-08-01

    Glass transition in thin (1-200 nm thick) spin-cast polystyrene films on silicon surfaces is probed by ellipsometry in a controlled vacuum environment. A temperature-modulated modification of the method is used alongside a traditional linear temperature scan. A clear glass transition is detected in films with thicknesses as low as 1-2 nm. The glass transition temperature (T(g)) shows no substantial dependence on thickness for coatings greater than 20 nm. Thinner films demonstrate moderate T(g) depression achieving 18 K for thicknesses 4-7 nm. Less than 4 nm thick samples are excluded from the T(g) comparison due to significant thickness nonuniformity (surface roughness). The transition in 10-20 nm thick films demonstrates excessive broadening. For some samples, the broadened transition is clearly resolved into two separate transitions. The thickness dependence of the glass transition can be well described by a simple 2-layer model. It is also shown that T(g) depression in 5 nm thick films is not sensitive to a wide range of experimental factors including molecular weight characteristics of the polymer, specifications of solvent used for spin casting, substrate composition, and pretreatment of the substrate surface.

  18. Optically nonlinear Bragg diffracting nanosecond optical switches

    NASA Astrophysics Data System (ADS)

    Pan, Guisheng

    We prepared low refractive index crystalline colloidal arrays (CCA) from highly charged fluorinated monodisperse spherical particles synthesized by emulsion polymerization of 1H,1H-heptafluorobutyl methacrylate. We have also covalently attached dyes to the fluorinated particles to prepare absorbing CCA. We photopolymerized these dyed CCA within a polyacrylamide matrix to form a polymerized crystalline colloidal array (PCCA). These semi-solid PCCA can withstand vibrations, ionic impurity addition and thermal shocks while maintaining the CCA ordering. The medium within the PCCA can easily be exchanged to exactly refractive index match the CCA. Thus, we were able to prepare a material where the real part of the refractive index was matched, while preserving a periodic modulation of the imaginary part of the refractive index. Under low light intensities the CCA is refractive index matched to the medium and does not diffract. However, high incident intensity illumination within the dye absorption band heats the particles within nsec to decrease their refractive index. This results in a mesoscopically periodic refractive index modulation with the periodicity of the CCA lattice. The array 'pops up' to diffract light within 2.5 nsec. These intelligent CCA hydrogels may have applications in optical limiting, optical computing and nsec fast optical switching devices, etc. We have also measured the polarization dependence of the Bragg diffraction efficiency of a CCA and compared the experimental results to that predicted by theory. The diffraction efficiency is maximized for σ polarization light at Bragg angle (θB) of 90o and minimized to zero for π polarized light at θB=45o. Our experimental diffraction and transmission results quantitatively agree with the predictions of Dynamical Diffraction Theory.

  19. Fraunhofer diffraction of coherent and incoherent nuclear matter waves by complementary screens

    NASA Astrophysics Data System (ADS)

    da Silveira, R.; Leclercq-Willain, Ch.

    2013-06-01

    The analogy between Fraunhofer diffraction effects observed in nuclear and subnuclear collisions and those observed with light diffracted by complementary screens is revisited. Emphasis will be put on the collision mechanisms playing a role analogous to that of an aperture in light diffraction. These analogies are illustrated with examples involving coherent and incoherent nuclear matter waves.

  20. Multipath analysis diffraction calculations

    NASA Technical Reports Server (NTRS)

    Statham, Richard B.

    1996-01-01

    This report describes extensions of the Kirchhoff diffraction equation to higher edge terms and discusses their suitability to model diffraction multipath effects of a small satellite structure. When receiving signals, at a satellite, from the Global Positioning System (GPS), reflected signals from the satellite structure result in multipath errors in the determination of the satellite position. Multipath error can be caused by diffraction of the reflected signals and a method of calculating this diffraction is required when using a facet model of the satellite. Several aspects of the Kirchhoff equation are discussed and numerical examples, in the near and far fields, are shown. The vector form of the extended Kirchhoff equation, by adding the Larmor-Tedone and Kottler edge terms, is given as a mathematical model in an appendix. The Kirchhoff equation was investigated as being easily implemented and of good accuracy in the basic form, especially in phase determination. The basic Kirchhoff can be extended for higher accuracy if desired. A brief discussion of the method of moments and the geometric theory of diffraction is included, but seems to offer no clear advantage in implementation over the Kirchhoff for facet models.

  1. Observation of discrete diffraction patterns in an optically induced lattice.

    PubMed

    Sheng, Jiteng; Wang, Jing; Miri, Mohammad-Ali; Christodoulides, Demetrios N; Xiao, Min

    2015-07-27

    We have experimentally observed the discrete diffraction of light in a coherently prepared multi-level atomic medium. This is achieved by launching a probe beam into an optical lattice induced from the interference of two coupling beams. The diffraction pattern can be controlled through the atomic parameters such as two-photon detuning and temperature, as well as orientations of the coupling and probe beams. Clear diffraction patterns occur only near the two-photon resonance.

  2. Sub-nanometer expansions of redox responsive polymer films monitored by imaging ellipsometry

    NASA Astrophysics Data System (ADS)

    Cumurcu, Aysegul; Feng, Xueling; Ramos, Lionel Dos; Hempenius, Mark A.; Schön, Peter; Vancso, G. Julius

    2014-09-01

    We describe a novel approach to quantitatively visualize sub nm height changes occurring in thin films of redox active polymers upon reversible electrochemical oxidation/reduction in situ and in real-time with electrochemical imaging ellipsometry (EC-IE). Our approach is based on the utilization of a micro-patterned substrate containing circular patterns of passive (non-redox active) 11-mercapto-1-undecanol (MCU) within a redox-responsive oligoethylene sulfide end-functionalized poly(ferrocenyldimethylsilane) (ES-PFS) film on a gold substrate. The non-redox responsive MCU layer was used as a molecular reference layer for the direct visualization of the minute thickness variations of the ES-PFS film. The ellipsometric microscopy images were recorded in aqueous electrolyte solutions at potentials of -0.1 V and 0.6 V vs. Ag/AgCl corresponding to the reduced and oxidized redox states of ES-PFS, respectively. The ellipsometric contrast images showed a 37 (+/-2)% intensity increase in the ES-PFS layer upon oxidation. The thickness of the ES-PFS layer reversibly changed between 4.0 (+/-0.1) nm and 3.4 (+/-0.1) nm upon oxidation and reduction, respectively, as determined by IE. Additionally, electrochemical atomic force microscopy (EC-AFM) was used to verify the redox controlled thickness variations. The proposed method opens novel avenues to optically visualize minute and rapid height changes occurring e.g. in redox active (and other stimulus responsive) polymer films in a fast and non-invasive manner.We describe a novel approach to quantitatively visualize sub nm height changes occurring in thin films of redox active polymers upon reversible electrochemical oxidation/reduction in situ and in real-time with electrochemical imaging ellipsometry (EC-IE). Our approach is based on the utilization of a micro-patterned substrate containing circular patterns of passive (non-redox active) 11-mercapto-1-undecanol (MCU) within a redox-responsive oligoethylene sulfide end

  3. Study of CuPt-type ordering and dopant effect of In{sub 0.5}Ga{sub 0.5}P/GaAs using spectroscopic ellipsometry

    SciTech Connect

    Lee, H. |; Klein, M.V.; Olson, J.M.; Hsieh, K.C.

    1994-09-01

    The CuPt-type ordering and dopant effects of In{sub 0.5}Ga{sub 0.5}P/GaAs epitaxial layers have been studied using spectroscopic ellipsometry and transmission electron microscopy. The degree of ordering was estimated by both transmission electron diffraction and direct band edge, E{sub 0}. Conventional lineshape fitting of E{sub 1}, E{sub 1}+{Delta}{sub 1}, and E{sub 2} gaps using the second derivative of pseudo dielectric functions shows that the peak position and oscillator strength of the E{sub 1} gap are basically a function of CuPt-type ordering whereas their broadening and phase depend mainly on carrier concentration. The decrease of E{sub 1} gap is explained in terms of CuPt-type ordering. In contrast to the E{sub 1} gap, all the lineshape parameters of the E{sub 2} gap depend mainly on CuPt-type ordering. This difference is discussed in terms of apparent {open_quotes}CuAu-type ordering{close_quotes} or Y2 structure which was observed by transmission electron diffraction.

  4. Single molecule diffraction.

    PubMed

    Spence, J C H; Doak, R B

    2004-05-14

    For solving the atomic structure of organic molecules such as small proteins which are difficult to crystallize, the use of a jet of doped liquid helium droplets traversing a continuous high energy electron beam is proposed as a means of obtaining electron diffraction patterns (serial crystallography). Organic molecules (such as small proteins) within the droplet (and within a vitreous ice jacket) may be aligned by use of a polarized laser beam. Iterative methods for solving the phase problem are indicated. Comparisons with a related plan for pulsed x-ray diffraction from single proteins in a molecular beam are provided.

  5. Biopolymer holographic diffraction gratings

    NASA Astrophysics Data System (ADS)

    Savić Šević, Svetlana; Pantelić, Dejan

    2008-03-01

    Surface-relief diffraction gratings are holographically recorded in dextran sensitized with ammonium dichromate (DCD). DCD was exposed with single-frequency 200 mW diode pumped ND-YAG laser, at 532 nm. The diffraction grating profiles were analyzed by atomic force microscopy (AFM). It was found that different surface profiles could be obtained. Gratings with 330 lines/mm spatial frequencies were made. Existence of higher harmonics in Fourier Transform of non-sinusoidal profiles shows that DCD is capable of recording spatial frequencies up to 1320 lines/mm (four times fundamental frequency). The measured maximum relief depth of the DCD grating is 402 nm.

  6. Temperature-Dependent Ellipsometry Measurements of Partial Coulomb Energy in Superconducting Cuprates

    DOE PAGES

    Levallois, J.; Tran, M. K.; Pouliot, D.; ...

    2016-08-24

    Here we performed an experimental study of the temperature and doping dependence of the energy-loss function of the bilayer and trilayer bismuth cuprates family. The primary aim is to obtain information on the energy stored in the Coulomb interaction between the conduction electrons, on the temperature dependence thereof, and on the change of Coulomb interaction when Cooper pairs are formed. We performed temperature-dependent ellipsometry measurements on several Bi2Sr2CaCu2O8₋x single crystals: underdoped with Tc=60, 70, and 83 K; optimally doped with Tc=91 K; overdoped with Tc=84, 81, 70, and 58 K; as well as optimally doped Bi2Sr2Ca2Cu3O10+x with Tc=110 K. Ourmore » first observation is that, as the temperature drops through Tc, the loss function in the range up to 2 eV displays a change of temperature dependence as compared to the temperature dependence in the normal state. This effect at—or close to—Tc depends strongly on doping, with a sign change for weak overdoping. The size of the observed change in Coulomb energy, using an extrapolation with reasonable assumptions about its q dependence, is about the same size as the condensation energy that has been measured in these compounds. Our results therefore lend support to the notion that the Coulomb energy is an important factor for stabilizing the superconducting phase. Lastly, because of the restriction to small momentum, our observations do not exclude a possible significant contribution to the condensation energy of the Coulomb energy associated with the region of q around (π,π).« less

  7. Spectral ellipsometry of GaSb and GaInAsSb: Experiment and modeling

    SciTech Connect

    Charache, G.W.; Mu {tilde n}oz, M.; Wei, K.; Pollak, F.H.; Freeouf, J.L.

    1999-06-30

    The optical constants {epsilon}(E)[={epsilon}{sub 1}(E)+i{epsilon}{sub 2}(E)] of single-crystal GaSb at 300K have been measured using spectral ellipsometry in the range of 0.3-5.3 eV. The {epsilon}(E) spectra displayed distinct structures associated with critical points (CPs) at E{sub 0} (direct gap), spin-orbit split E{sub 0}+{Delta}{sub 0} component, spin-orbit split (E{sub 1}, E{sub 1}+{Delta}{sub 1}) and (E{sub 0}{prime}, E{sub 0}{prime}+{Delta}{sub 0}{prime}) doublets, as well as E{sub 2}. The experimental data over the entire measured spectral range (after oxide removal) has been fit using the Holden model dielectric function based on the electronic energy-band structure near these CPs plus excitonic and band-to-band Coulomb enhancement effects at E{sub 0}, E{sub 0}+{Delta}{sub 0} and the E{sub 1}, E{sub 1}+{Delta}{sub 1} doublet. In addition to evaluating the energies of these various band-to-band CPs, information about the binding energy (R{sub 1}) of the two-dimensional exciton related to the E{sub 1}, E{sub 1}+{Delta}{sub 1} CPs was obtained. The value of R{sub 1} was in good agreement with effective mass/k{sup {rightharpoonup}}{center_dot}p{sup {rightharpoonup}} theory. The ability to evaluate R{sub 1} has important ramifications for recent first-principles band structure calculations which include exciton effects at E{sub 0}, E{sub 1}, and E{sub 2}. The experimental results were compared to other evaluations of the optical constants of GaSb.

  8. Temperature-Dependent Ellipsometry Measurements of Partial Coulomb Energy in Superconducting Cuprates

    NASA Astrophysics Data System (ADS)

    Levallois, J.; Tran, M. K.; Pouliot, D.; Presura, C. N.; Greene, L. H.; Eckstein, J. N.; Uccelli, J.; Giannini, E.; Gu, G. D.; Leggett, A. J.; van der Marel, D.

    2016-07-01

    We performed an experimental study of the temperature and doping dependence of the energy-loss function of the bilayer and trilayer bismuth cuprates family. The primary aim is to obtain information on the energy stored in the Coulomb interaction between the conduction electrons, on the temperature dependence thereof, and on the change of Coulomb interaction when Cooper pairs are formed. We performed temperature-dependent ellipsometry measurements on several Bi2 Sr2 CaCu2 O8 -x single crystals: underdoped with Tc=60 , 70, and 83 K; optimally doped with Tc=91 K ; overdoped with Tc=84 , 81, 70, and 58 K; as well as optimally doped Bi2 Sr2 Ca2 Cu3 O10 +x with Tc=110 K . Our first observation is that, as the temperature drops through Tc, the loss function in the range up to 2 eV displays a change of temperature dependence as compared to the temperature dependence in the normal state. This effect at—or close to—Tc depends strongly on doping, with a sign change for weak overdoping. The size of the observed change in Coulomb energy, using an extrapolation with reasonable assumptions about its q dependence, is about the same size as the condensation energy that has been measured in these compounds. Our results therefore lend support to the notion that the Coulomb energy is an important factor for stabilizing the superconducting phase. Because of the restriction to small momentum, our observations do not exclude a possible significant contribution to the condensation energy of the Coulomb energy associated with the region of q around (π ,π ).

  9. The Heisenberg Uncertainty Principle Demonstrated with An Electron Diffraction Experiment

    ERIC Educational Resources Information Center

    Matteucci, Giorgio; Ferrari, Loris; Migliori, Andrea

    2010-01-01

    An experiment analogous to the classical diffraction of light from a circular aperture has been realized with electrons. The results are used to introduce undergraduate students to the wave behaviour of electrons. The diffraction fringes produced by the circular aperture are compared to those predicted by quantum mechanics and are exploited to…

  10. Fabrication and applications of large aperture diffractive optics

    SciTech Connect

    Dixit, S; Britten, J B; Hyde, R; Rushford, M; Summers, L; Toeppen, J

    2002-02-19

    Large aperture diffractive optics are needed in high power laser applications to protect against laser damage during operation and in space applications to increase the light gathering power and consequently the signal to noise. We describe the facilities we have built for fabricating meter scale diffractive optics and discuss several examples of these.

  11. Diffractive element in extreme-UV lithography condenser

    DOEpatents

    Sweatt, William C.; Ray-Chaudhuri, Avijit

    2001-01-01

    Condensers having a mirror with a diffraction grating in projection lithography using extreme ultra-violet significantly enhances critical dimension control. The diffraction grating has the effect of smoothing the illumination at the camera's entrance pupil with minimum light loss. Modeling suggests that critical dimension control for 100 nm features can be improved from 3 nm to less than about 0.5 nm.

  12. Diffractive element in extreme-UV lithography condenser

    DOEpatents

    Sweatt, William C.; Ray-Chaudhurl, Avijit K.

    2000-01-01

    Condensers having a mirror with a diffraction grating in projection lithography using extreme ultra-violet significantly enhances critical dimension control. The diffraction grating has the effect of smoothing the illumination at the camera's entrance pupil with minimum light loss. Modeling suggests that critical dimension control for 100 nm features can be improved from 3 nm to less than about 0.5 nm.

  13. Measuring Slit Width and Separation in a Diffraction Experiment

    ERIC Educational Resources Information Center

    Gan, K. K.; Law, A. T.

    2009-01-01

    We present a procedure for measuring slit width and separation in single- and double-slit diffraction experiments. Intensity spectra of diffracted laser light are measured with an optical sensor (PIN diode). Slit widths and separations are extracted by fitting to the measured spectra. We present a simple fitting procedure to account for the…

  14. The Heisenberg Uncertainty Principle Demonstrated with An Electron Diffraction Experiment

    ERIC Educational Resources Information Center

    Matteucci, Giorgio; Ferrari, Loris; Migliori, Andrea

    2010-01-01

    An experiment analogous to the classical diffraction of light from a circular aperture has been realized with electrons. The results are used to introduce undergraduate students to the wave behaviour of electrons. The diffraction fringes produced by the circular aperture are compared to those predicted by quantum mechanics and are exploited to…

  15. Measuring Slit Width and Separation in a Diffraction Experiment

    ERIC Educational Resources Information Center

    Gan, K. K.; Law, A. T.

    2009-01-01

    We present a procedure for measuring slit width and separation in single- and double-slit diffraction experiments. Intensity spectra of diffracted laser light are measured with an optical sensor (PIN diode). Slit widths and separations are extracted by fitting to the measured spectra. We present a simple fitting procedure to account for the…

  16. Multichannel Spectroscopic Ellipsometry for CdTe Photovoltaics: from Materials and Interfaces to Solar Cells

    NASA Astrophysics Data System (ADS)

    Koirala, Prakash

    Spectroscopic ellipsometry (SE) in the mid-infrared to ultraviolet range has been implemented in order to develop and evaluate optimization procedures for CdTe solar cells at the different stages of fabrication. In this dissertation research, real time SE (RT-SE) has been applied during the fabrication of the as-deposited CdS/CdTe solar cell. Two areas of background research were addressed before undertaking the challenging RT-SE analysis procedures. First, optical functions were parameterized versus temperature for the glass substrate and its overlayers, including three different SnO2 layers. This database has applications not only for RT-SE analysis but also for on-line monitoring of the coated glass itself at elevated temperature. Second, post-deposition modifications of substrate have been studied by infrared spectroscopic ellipsometry (IR-SE) prior to the RT-SE analysis in order to evaluate the need for such modification in the analysis. With support from these background studies, RT-SE has been implemented in analyses of the evolution of the thin film structural properties during sputter deposition of polycrystalline CdS/CdTe solar cells on the transparent conducting oxide (TCO) coated glass substrates. The real time optical spectra collected during CdS/CdTe deposition were analyzed using the optical property database for all substrate components as a function of measurement temperature. RT-SE enables characterization of the filling process of the surface roughness modulations on the top-most SnO2 substrate layer, commonly referred to as the high resistivity transparent (HRT) layer. In this filling process, the optical properties of this surface layer are modified in accordance with an effective medium theory. In addition to providing information on interface formation to the substrate during film growth, RT-SE also provides information on the bulk layer CdS growth, its surface roughness evolution, as well as overlying CdTe interface formation and bulk layer

  17. Explanation and observability of diffraction in time

    SciTech Connect

    Torrontegui, E.; Muga, J. G.; Munoz, J.; Ban, Yue

    2011-04-15

    Diffraction in time (DIT) is a fundamental phenomenon in quantum dynamics due to time-dependent obstacles and slits. It is formally analogous to diffraction of light, and is expected to play an increasing role in the design of coherent matter wave sources, as in the atom laser, to analyze time-of-flight information and emission from ultrafast pulsed excitations, and in applications of coherent matter waves in integrated atom-optical circuits. We demonstrate that DIT emerges robustly in quantum waves emitted by an exponentially decaying source and provide a simple explanation of the phenomenon, as an interference of two characteristic velocities. This allows for its controllability and optimization.

  18. Computational imaging using lightweight diffractive-refractive optics.

    PubMed

    Peng, Yifan; Fu, Qiang; Amata, Hadi; Su, Shuochen; Heide, Felix; Heidrich, Wolfgang

    2015-11-30

    Diffractive optical elements (DOE) show great promise for imaging optics that are thinner and more lightweight than conventional refractive lenses while preserving their light efficiency. Unfortunately, severe spectral dispersion currently limits the use of DOEs in consumer-level lens design. In this article, we jointly design lightweight diffractive-refractive optics and post-processing algorithms to enable imaging under white light illumination. Using the Fresnel lens as a general platform, we show three phase-plate designs, including a super-thin stacked plate design, a diffractive-refractive-hybrid lens, and a phase coded-aperture lens. Combined with cross-channel deconvolution algorithm, both spherical and chromatic aberrations are corrected. Experimental results indicate that using our computational imaging approach, diffractive-refractive optics is an alternative candidate to build light efficient and thin optics for white light imaging.

  19. Calculating cellulose diffraction patterns

    USDA-ARS?s Scientific Manuscript database

    Although powder diffraction of cellulose is a common experiment, the patterns are not widely understood. The theory is mathematical, there are numerous different crystal forms, and the conventions are not standardized. Experience with IR spectroscopy is not directly transferable. An awful error, tha...

  20. DIFFRACTION FROM MODEL CRYSTALS

    USDA-ARS?s Scientific Manuscript database

    Although calculating X-ray diffraction patterns from atomic coordinates of a crystal structure is a widely available capability, calculation from non-periodic arrays of atoms has not been widely applied to cellulose. Non-periodic arrays result from modeling studies that, even though started with at...

  1. Diffract, then destroy

    NASA Astrophysics Data System (ADS)

    Ball, Philip

    2016-09-01

    A new implementation of X-ray diffraction using free-electron lasers can take snapshots of biological molecules that are inaccessible via X-ray crystallography. As Philip Ball reports, the technique can even be used to create stop-motion films of dynamic molecular processes

  2. Inclusive diffraction at HERA

    SciTech Connect

    Favart, Laurent

    2011-07-15

    Results are reported on recent measurements, performed by the H1 and ZEUS Collaborations, of the cross section of the diffractive deep-inelastic process ep{yields}eXp using different experimental methods. In particular, first results using the Very Forward Proton Spectrometer of H1 are discussed.

  3. High-end spectroscopic diffraction gratings: design and manufacturing

    NASA Astrophysics Data System (ADS)

    Glaser, Tilman

    2015-02-01

    Diffraction gratings are key components for spectroscopic systems. For high-end applications, they have to meet advanced requirements as, e.g., maximum efficiency, lowest possible scattered light level, high numerical aperture, and minimal aberrations. Diffraction gratings are demanded to allow spectrometer designs with highest resolution, a maximal étendue, and minimal stray light, built within a minimal volume. This tutorial is intended to provide an overview of different high-end spectroscopic gratings, their theoretical design and manufacturing technologies.

  4. Impedance Matched to Vacuum, Invisible Edge, Diffraction Suppressed Mirror

    NASA Technical Reports Server (NTRS)

    Hagopian, John G. (Inventor); Roman, Patrick A. (Inventor); Shiri, Sharham (Inventor); Wollack, Edward J. (Inventor)

    2015-01-01

    Diffraction suppressed mirrors having an invisible edge are disclosed for incident light at both targeted wavelengths and broadband incident light. The mirrors have a first having at least one discontiguous portion having a plurality of nanostructured apertures. The discontiguous mirror portion impedance matches a relatively high impedance portion of the mirror to a relatively low impedance portion of the mirror, thereby reducing the diffraction edge effect otherwise present in a conventional mirror.

  5. Diffractive flat panel solar concentrators of a novel design.

    PubMed

    de Jong, Ties M; de Boer, Dick K G; Bastiaansen, Cees W M

    2016-07-11

    A novel design for a flat panel solar concentrator is presented which is based on a light guide with a grating applied on top that diffracts light into total internal reflection. By combining geometrical and diffractive optics the geometrical concentration ratio is optimized according to the principles of nonimaging optics, while the thickness of the device is minimized due to the use of total internal reflection.

  6. Coherent x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Pitney, John Allen

    Conventional x-ray diffraction has historically been done under conditions such that the measured signal consists of an incoherent addition of scattering which is coherent only on a length scale determined by the properties of the beam. The result of the incoherent summation is a statistical averaging over the whole illuminated volume of the sample, which yields certain kinds of information with a high degree of precision and has been key to the success of x-ray diffraction in a variety of applications. Coherent x-ray scattering techniques, such as coherent x-ray diffraction (CXD) and x-ray intensity fluctuation spectroscopy (XIFS), attempt to reduce or eliminate any incoherent averaging so that specific, local structures couple to the measurement without being averaged out. In the case of XIFS, the result is analogous to dynamical light scattering, but with sensitivity to length scales less than 200 nm and time scales from 10-3 s to 103 s. When combined with phase retrieval, CXD represents an imaging technique with the penetration, in situ capabilities, and contrast mechanisms associated with x-rays and with a spatial resolution ultimately limited by the x-ray wavelength. In practice, however, the spatial resolution of CXD imaging is limited by exposure to about 100 A. This thesis describes CXD measurements of the binary alloy Cu3Au and the adaptation of phase retrieval methods for the reconstruction of real-space images of Cu3Au antiphase domains. The theoretical foundations of CXD are described in Chapter 1 as derived from the kinematical formulation for x-ray diffraction and from the temporal and spatial coherence of radiation. The antiphase domain structure of Cu 3Au is described, along with the associated reciprocal-space structure which is measured by CXD. CXD measurements place relatively stringent requirements on the coherence properties of the beam and on the detection mechanism of the experiment; these requirements and the means by which they have been

  7. Nonlocal Interactions between Two Spatially Divided Light Fluxes

    NASA Astrophysics Data System (ADS)

    Sargsyan, R. Sh.; Karamyan, G. G.; Gevorkyan, A. S.; Manukyan, A. M.; Va rdanyan, V. T.; Nikoghosyan, A. G.; Sargsyan, V. R.

    2011-03-01

    Experiments with light scattering from diffraction slit are carried out. The changes in light intensities were observed when light was propagated through the remote coil of optical fiber in vicinity of diffraction slit. The time dependencies of intensities of scattered light in different diffraction zones are measured and analyzed. The qualitative interpretation of observed effects is proposed.

  8. Corrosion under argon irradiation of titanium in the low MeV range: A study coupling AFM and Spectroscopic Ellipsometry

    NASA Astrophysics Data System (ADS)

    Do, Ngoc-Long; Garcia-Caurel, Enric; Bérerd, Nicolas; Moncoffre, Nathalie; Gorse-Pomonti, Dominique

    2014-05-01

    This paper reports on a recent study of the corrosion under argon ion irradiation of titanium in the low MeV range (1-9 MeV), associating AFM and Spectroscopic Ellipsometry. Irradiation with MeV Arn+ (n = 1, 3) ions produces damages on the titanium surface. Large craters form on the oxidized titanium surface whose characteristics vary as a function of the argon energy between 2 and 9 MeV. The superficial oxide grows thicker under irradiation over the same energy range, especially near 3 MeV. It is suggested that collisions cascades play a significant role in the overall damage process.

  9. In situ assessment of the contact angles of nanoparticles adsorbed at fluid interfaces by multiple angle of incidence ellipsometry.

    PubMed

    Stocco, Antonio; Su, Ge; Nobili, Maurizio; In, Martin; Wang, Dayang

    2014-09-28

    Here multiple angle of incidence ellipsometry was successfully applied to in situ assess the contact angle and surface coverage of gold nanoparticles as small as 18 nm, coated with stimuli-responsive polymers, at water-oil and water-air interfaces in the presence of NaCl and NaOH, respectively. The interfacial adsorption of the nanoparticles was found to be very slow and took days to reach a fairly low surface coverage. For water-oil interfaces, in situ nanoparticle contact angles agree with the macroscopic equilibrium contact angles of planar gold surfaces with the same polymer coatings, whilst for water-air interfaces, significant differences have been observed.

  10. Thin-film coalescence in hydrogenated amorphous silicon probed by spectroscopic ellipsometry with millisecond-scale resolution

    NASA Astrophysics Data System (ADS)

    Li, Y.-M.; An, Ilsin; Nguyen, H. V.; Wronski, C. R.; Collins, R. W.

    1992-05-01

    New developments in spectroscopic ellipsometry (1.5<=hν<=4.3 eV) now provide quantitative information on thin films with a time resolution of 16 ms. We report submonolayer sensitivity to a surface smoothening effect associated with nuclei coalescence in the early stages of hydrogenated amorphous silicon (a-Si:H) preparation by plasma-enhanced chemical vapor deposition. An investigation of a-Si:H prepared on c-Si and Cr substrates under different conditions of substrate temperature and plasma power discloses a clear correlation between the magnitude of this effect and the ultimate bulk properties of the material.

  11. Diffraction manipulation by four-wave mixing.

    PubMed

    Katzir, Itay; Ron, Amiram; Firstenberg, Ofer

    2015-03-09

    We suggest a scheme to manipulate paraxial diffraction by utilizing the dependency of a four-wave mixing process on the relative angle between the light fields. A microscopic model for four-wave mixing in a Λ-type level structure is introduced and compared to recent experimental data. We show that images with feature size as low as 10 μm can propagate with very little or even negative diffraction. The mechanism is completely different from that conserving the shape of spatial solitons in nonlinear media, as here diffraction is suppressed for arbitrary spatial profiles. At the same time, the gain inherent to the nonlinear process prevents loss and allows for operating at high optical depths. Our scheme does not rely on atomic motion and is thus applicable to both gaseous and solid media.

  12. Diffractive elements performance in chromatic confocal microscopy

    NASA Astrophysics Data System (ADS)

    Garzón, J.; Duque, D.; Alean, A.; Toledo, M.; Meneses, J.; Gharbi, T.

    2011-01-01

    The Confocal Laser Scanning Microscopy (CLSM) has been widely used in the semiconductor industry and biomedicine because of its depth discrimination capability. Subsequent to this technique has been developed in recent years Chromatic Confocal Microscopy. This method retains the same principle of confocal and offers the added advantage of removing the axial movement of the moving system. This advantage is usually accomplished with an optical element that generates a longitudinal chromatic aberration and a coding system that relates the axial position of each point of the sample with the wavelength that is focused on each. The present paper shows the performance of compact chromatic confocal microscope when some different diffractive elements are used for generation of longitudinal chromatic aberration. Diffractive elements, according to the process and manufacturing parameters, may have different diffraction efficiency and focus a specific wavelength in a specific focal position. The performance assessment is carried out with various light sources which exhibit an incoherent behaviour and a broad spectral width.

  13. Fabrication techniques for very fast diffractive lenses

    NASA Technical Reports Server (NTRS)

    Tai, Anthony M.; Marron, Joseph C.

    1993-01-01

    Aspheric lenses with arbitrary phase functions can be fabricated on thin light weight substrates via the binary optics fabrication technique. However, it is difficult and costly to fabricate a fast lens (f/number less than 1) for use as the shorter wavelengths. The pitch of the masks and the alignment accuracy must be very fine. For a large lens, the space-bandwidth product of the element can also become impractically large. In this paper, two alternate approaches for the fabrication of fast aspheric diffractive lenses are described. The first approach fabricates the diffractive lens interferometrically, utilizing a spherical wavefront to provide the optical power of the lens and a computer generated hologram to create the aspheric components. The second approach fabricates the aspheric diffractive lens in the form if a higher order kinoform which trades groove profile fidelity for coarser feature size. The design and implementation issues for these two fabrication techniques are discussed.

  14. Adaptable Diffraction Gratings With Wavefront Transformation

    NASA Technical Reports Server (NTRS)

    Iazikov, Dmitri; Mossberg, Thomas W.; Greiner, Christoph M.

    2010-01-01

    Diffraction gratings are optical components with regular patterns of grooves, which angularly disperse incoming light by wavelength. Traditional diffraction gratings have static planar, concave, or convex surfaces. However, if they could be made so that they can change the surface curvature at will, then they would be able to focus on particular segments, self-calibrate, or perform fine adjustments. This innovation creates a diffraction grating on a deformable surface. This surface could be bent at will, resulting in a dynamic wavefront transformation. This allows for self-calibration, compensation for aberrations, enhancing image resolution in a particular area, or performing multiple scans using different wavelengths. A dynamic grating gives scientists a new ability to explore wavefronts from a variety of viewpoints.

  15. FLC diffraction grating: Efficiency enhancement by SWCNT doping

    NASA Astrophysics Data System (ADS)

    Gupta, Swadesh Kumar; Singh, Dharmendra Pratap; Manohar, Rajiv

    2013-06-01

    At present, Ferroelectric liquid crystals (FLCs) are well known for their use as a switchable grating in surface stabilized mode. The efficiency of such gratings is not attractive enough to be used in devices. An approach that uses an electro-optically tunable phase grating to enhance the diffraction efficiency is proposed here. The doping of Single wall carbon nanotubes (SWCNTs) in pure FLC has shown improved diffraction efficiency. The observations indicate towards the phase diffraction phenomenon. The enhanced efficiency of first order diffraction suggests the use of present system in holography and different spatial light modulators.

  16. Optical laue diffraction on photonic structures designed by laser lithography

    NASA Astrophysics Data System (ADS)

    Samusev, K. B.; Rybin, M. V.; Lukashenko, S. Yu.; Limonov, M. F.

    2016-06-01

    Two-dimensional photonic crystals with square symmetry C 4v were obtained using the laser lithography method. The structure of these samples was studied by scanning electron microscopy. Optical Laue diffraction for monochromatic light was studied experimentally depending on the incidence angle of laser beam and lattice constant. Interpretation of the observed diffraction patterns is given in the framework of the Laue diffraction mechanism for an one-dimensional chain of scattering elements. Red thresholds for different diffraction orders were determined experimentally and theoretically. The results of calculations are in an excellent agreement with experiment.

  17. Diffraction of three-colour radiation on an acoustic wave

    SciTech Connect

    Kotov, V M

    2015-07-31

    We study acousto-optic Bragg diffraction of three-colour radiation having wavelengths of 488, 514 and 633 nm on a single acoustic wave propagating in a TeO{sub 2} crystal. A technique is developed that allows one to find diffraction regimes with a proportional change in the intensity of all radiations by varying the acoustic power. According to the technique, radiation with a maximum wavelength has to be in strict Bragg synchronism with the acoustic wave, while other radiations diffract during the synchronism detuning. The results obtained using this technique are experimentally confirmed. (diffraction of light)

  18. Central diffraction at ALICE

    NASA Astrophysics Data System (ADS)

    Lämsä, J. W.; Orava, R.

    2011-02-01

    The ALICE experiment is shown to be well suited for studies of exclusive final states from central diffractive reactions. The gluon-rich environment of the central system allows detailed QCD studies and searches for exotic meson states, such as glueballs, hybrids and new charmonium-like states. It would also provide a good testing ground for detailed studies of heavy quarkonia. Due to its central barrel performance, ALICE can accurately measure the low-mass central systems with good purity. The efficiency of the Forward Multiplicity Detector (FMD) and the Forward Shower Counter (FSC) system for detecting rapidity gaps is shown to be adequate for the proposed studies. With this detector arrangement, valuable new data can be obtained by tagging central diffractive processes.

  19. Analysis and optimization of thin film photovoltaic materials and device fabrication by real time spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Li, Jian; Stoke, Jason A.; Podraza, Nikolas J.; Sainju, Deepak; Parikh, Anuja; Cao, Xinmin; Khatri, Himal; Barreau, Nicolas; Marsillac, Sylvain; Deng, Xunming; Collins, Robert W.

    2007-09-01

    Methods of spectroscopic ellipsometry (SE) have been applied to investigate the growth and properties of the material components used in the three major thin film photovoltaics technologies: (1) hydrogenated silicon (Si:H); (2) cadmium telluride (CdTe); and (3) copper indium-gallium diselenide (CuIn 1-xGa xSe2 or CIGS). In Si:H technology, real time SE (RTSE) has been applied to establish deposition phase diagrams that describe very high frequency (vhf) plasmaenhanced chemical vapor deposition (PECVD) processes for hydrogenated silicon (Si:H) and silicon-germanium alloy (Si 1-xGe x:H) thin films. This study has reaffirmed that the highest efficiencies for a-Si:H and a-Si 1-xGe x:H component solar cells of multijunction devices are obtained when the i-layers are prepared under maximal H II dilution conditions. In CdTe technology, the magnetron sputter deposition of polycrystalline CdTe, CdS, and CdTe 1-xS x thin films as well as the formation of CdS/CdTe and CdTe/CdS heterojunctions has been studied. The nucleation and growth behaviors of CdTe and CdS show strong variations with deposition temperature, and this influences the ultimate grain size. The dielectric functions ɛ of the CdTe 1-xS x alloys have been deduced in order to set up a database for real time investigation of inter-diffusion at the CdS/CdTe and CdTe/CdS interfaces. In CIGS technology, strong variations in ɛ of the Mo back contact during sputter deposition have been observed, and these results have been understood applying a Drude relaxation time that varies with the Mo film thickness. Ex-situ SE measurements of a novel In IIS 3 window layer have shown critical point structures at 2.77+/-0.08 eV, 4.92+/-0.005 eV, and 5.64+/-0.005 eV, as well as an absorption tail with an onset near 1.9 eV. Simulations of solar cell performance comparing In IIS 3 and the conventional CdS have revealed similar quantum efficiencies, suggesting the possibility of a Cd-free window layer in CIGS technology.

  20. SINGLE CRYSTAL NEUTRON DIFFRACTION.

    SciTech Connect

    KOETZLE,T.F.

    2001-03-13

    Single-crystal neutron diffraction measures the elastic Bragg reflection intensities from crystals of a material, the structure of which is the subject of investigation. A single crystal is placed in a beam of neutrons produced at a nuclear reactor or at a proton accelerator-based spallation source. Single-crystal diffraction measurements are commonly made at thermal neutron beam energies, which correspond to neutron wavelengths in the neighborhood of 1 Angstrom. For high-resolution studies requiring shorter wavelengths (ca. 0.3-0.8 Angstroms), a pulsed spallation source or a high-temperature moderator (a ''hot source'') at a reactor may be used. When complex structures with large unit-cell repeats are under investigation, as is the case in structural biology, a cryogenic-temperature moderator (a ''cold source'') may be employed to obtain longer neutron wavelengths (ca. 4-10 Angstroms). A single-crystal neutron diffraction analysis will determine the crystal structure of the material, typically including its unit cell and space group, the positions of the atomic nuclei and their mean-square displacements, and relevant site occupancies. Because the neutron possesses a magnetic moment, the magnetic structure of the material can be determined as well, from the magnetic contribution to the Bragg intensities. This latter aspect falls beyond the scope of the present unit; for information on magnetic scattering of neutrons see Unit 14.3. Instruments for single-crystal diffraction (single-crystal diffractometers or SCDs) are generally available at the major neutron scattering center facilities. Beam time on many of these instruments is available through a proposal mechanism. A listing of neutron SCD instruments and their corresponding facility contacts is included in an appendix accompanying this unit.