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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Optical loss due to diffraction by concentrator Fresnel lenses

Fresnel lenses are widely used in concentrating photovoltaic (CPV) systems as a primary optical element. They focus sunlight on small solar cells or on the entrance apertures of secondary optical elements. A Fresnel lens consists of several prism rings and diffraction by these prism rings is unavoidable. Some of the light that would reach a designated target area according to geometric optics will miss it due to diffraction. This diffraction loss may be of relevant magnitude for CPV applications. The results of published analytical calculations are evaluated, discussed, and compared to computer simulations and measurements.

14 SOLAR ENERGY↗
DOE OSTI2014

Measurement of coherence length and incoherent source size of hard x-ray undulator beamline at Pohang Light Source-II

We measured the spatial coherence length and incoherent source size of a hard x-ray undulator beamline at Pohang Light Source-II, the stored electron energy of which has been increased from 2.5 GeV to 3 GeV. The coherence length was determined by single-slit measurement of the visibility of the Fresnel diffraction pattern. The correlated incoherent source size was cross-checked for three different optics: the single slit, beryllium parabolic compound refractive lenses, and the Fresnel zone plate. We concluded that the undulator beamline has an effective incoherent source size (FWHM) of 540 μm (horizontal) × 50 μm (vertical)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Diffraction-assisted micropatterning of silicon surfaces by ns-laser irradiation

Single-pulse (532 nm, 8 ns) micropatterning of silicon with nanometric surface modulation is demonstrated by irradiating through a diffracting pinhole. The irradiation results obtained at fluences above the melting threshold are characterized by scanning electron and scanning force microscopy and reveal a good agreement with Fresnel diffraction theory. The physical mechanism is identified and discussed on basis of both thermocapillary and chemicapillary induced material transport during the molten state of the surface.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2011

Protein immobilization and detection on laser processed polystyrene surfaces

The bovine serum albumin (BSA)-polystyrene (PS) interface layer is laser photo activated at 157 nm for site selective multiple target-protein immobilization. The 5-15 nm photon induced interface layer has different chemical, wetting, and stiffness properties than the PS photon processed surface. The irradiated areas exhibit target-protein binding, followed by localized probe-target protein detection. The photon induced chemical modification of the BSA-PS interface layer is identified by: (1) Morphological, imaging, and analysis of surface parameters with atomic force microscopy, (2) spectroscopic shift (4 cm{sup -1}), of the amide I group and formation of new C=N, NH{sub 2}, C-O, C=O, and O-C=O groups following irradiation, identified with attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and (3) the different hydrophilic/hydrophobic and force-distance response of the bare PS and BSA-PS surfaces. Near field edge diffraction (Fresnel) fluorescence imaging specifies the threshold photon energy and the fluence required to optically detect the protein binding on the photon induced BSA-PS interface layer. By approximating the Fresnel integrals with analytical functions, the threshold photon energy and the fluence are expressed as the sum of zero, first, and second order harmonic terms of two characteristic diffracted modes and they are specified to be 8.73x10{sup -9} Jand623 J m{sup -2}, respectively. Furthermore, a bioarray of three probe-target proteins is fabricated with 1.5 {mu}m spatial resolution using a 157 nm laser microstepper. The methodology eliminates the use of intermediate polymer layers between the blocking BSA protein and the PS substrate in bioarray fabrication.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Microsized structures assisted nanostructure formation on ZnSe wafer by femtosecond laser irradiation

Micro/nano patterning of ZnSe wafer is demonstrated by femtosecond laser irradiation through a diffracting pinhole. The irradiation results obtained at fluences above the ablation threshold are characterized by scanning electron microscopy. The microsized structure with low spatial frequency has a good agreement with Fresnel diffraction theory. Laser induced periodic surface structures and laser-induced periodic curvelet surface structures with high spatial frequency have been found on the surfaces of microsized structures, such as spikes and valleys. We interpret its formation in terms of the interference between the reflected laser field on the surface of the valley and the incident laser pulse.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Generation of spiraling Bessel beams from dark/antidark Gaussian beams diffracted by a curved fork-shaped hologram

In this paper, we present a theoretical study on the generation of spiraling Bessel beams by illuminating a curved fork-shaped hologram (CFH) by spatially coherent dark/antidark Gaussian beams. The amplitude expression of the generated spiraling Bessel beam is obtained by using the framework of the Fresnel diffraction approach and by means of the stationary phase method. Numerical calculations show that upon propagating, the longitudinal intensity of the generated field reaches a threshold maximum value at a distance z{sub max}. It is demonstrated that z{sub max} increases with the increasing of the topological charge p and the order m. The result corresponding to the incident Gaussian beam diffracted by CFH is obtained as a particular case of this study.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Diffraction and thermal effect of a Bessel-Gaussian laser for Ag nanoparticle deposition

Nanoparticles are known to sinter at much lower temperatures than the corresponding bulk or micro size particles. A laser-assisted sintering process is considered in this study to sinter Ag nanoparticles by dispensing Ag paste onto an indium tin oxide-coated Si substrate. The Gaussian beam of a CO 2 laser source is propagated through axicon and biconvex lenses, and the resulting hollow beam is focused on the Ag paste with a hollow parabolic mirror. A Bessel-Gaussian irradiance distribution is obtained at the focal plane of the parabolic mirror due to the interference of the hollow laser cone. The Fresnel diffraction approximation is considered to determine the phasor of the laser and an analytical approach is implemented to calculate the irradiance distribution of the Bessel-Gaussian beam. This irradiance distribution is utilized as a heat source in a heat conduction model and the temperature distribution is analyzed for thin Ag films formed during the laser sintering of Ag nanoparticles. An analytical expression is obtained for the temperature distribution by solving the heat conduction equation using Fourier transform for finite media. The widths of the deposited Ag lines are predicted from the temperature profiles and the model predictions compare well with the experimental results. The isotherms are found to be geometrically noncongruent with convex and concave tips depending on the locally maximum and minimum irradiances of the Bessel-Gaussian beam, respectively. The convex and concave tips, however, appear in the same isotherm for sufficiently high substrate speed relative to the laser beam.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2011

The JEM-EUSO optics system

The Extreme Universe Space Observatory onboard the Japanese Experiment Module is an international mission devoted to the detection of ultra high-energy cosmic particles with energies E>7x10{sup 19} eV. They are revealed through emission in the atmosphere of Cherenkov and fluorescence light in the near-UV region, by using an optical system with 60 deg. field of view and a 2.3 m entrance pupil. One of the challenges consists in developing an unusual combination of large and lightweight refractive optics: two double-sided curved Fresnel lenses and a central curved Fresnel+diffractive lens, whose maximum dimensions are 2.65 m. This paper describes the development of such a optical system and its performances of the latest configurations.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2010

One-Micron Beams for Macromolecular Crystallography at GM/CA-CAT

GM/CA-CAT has developed a 1-{mu}m beam for challenging micro-diffraction experiments with macromolecular crystals (e.g. small crystals) and for radiation damage studies. Reflective (Kirkpatrick-Baez mirrors) and diffractive (Fresnel zone plates) optics have been used to focus the beam. Both cases are constrained by the need to maintain a small beam convergence. Using two different zone plates, 1.0x1.0 and 0.8x0.9 {mu}m{sup 2} (VxH,FWHM) beams were created at 15.2 keV and 18.5 keV, respectively. Additionally, by introducing a vertical focusing mirror upstream of the zone plate, a line focus at 15.2 keV was created (28x1.4 {mu}m{sup 2} VxH,FWHM) with the line oriented perpendicular to the X-ray polarization and the crystal rotation axis. Crystal-mounting stages with nanometer resolution have been assembled to profile these beams and to perform diffraction experiments.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Propagation characteristics of dark and antidark Gaussian beams in turbulent atmosphere

In this work, we investigated theoretically the propagation characteristics of dark and antidark Gaussian beams (DADGBs) in turbulent atmosphere. Based on the Huygens–Fresnel diffraction integral and by mean of the expansion form of a hard aperture function into a finite sum of Gaussian functions we derived analytically the on-axis intensity distribution of an apertured DADGB propagating in turbulent atmosphere. The dependence of the axial intensity distribution on the turbulent strength and on the parameters of the beam is illustrated with numerical examples. The results show that the axial intensity decreases rapidly when the turbulent strength parameter is large, and the propagation distance is shorter for large wavelengths and for small beam waist width.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Transformation of a generalized Bessel–Laguerre–Gaussian beam by a paraxial ABCD optical system

An analytical expression of a Generalized Bessel–Laguerre–Gaussian (GBLG) beam passing through a paraxial ABCD optical system is developed by using the generalized Huygens–Fresnel diffraction integral. This result is regarded as the main finding of this paper. Several studies such as the propagation of fundamental Gaussian, flat-topped Gaussian, Bessel–Gaussian, Generalized Bessel–Gaussian and Laguerre–Gaussian beams, through an ABCD optical system, are derived as particular cases of our principle investigation. Numerical simulations are performed, in this work, to illustrate the propagation properties of GBLG beam through a free space, a thin lens, a Fractional Fourier transform system and a quadratic graded-index system.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Production of Airy-related beams by an Airy transform optical system

Based on the process of Huygens–Fresnel diffraction integral, we investigate theoretically the characteristics of fields generated by diffracted controllable dark-hollow beams (CDHBs) through an Airy transform optical system. It is shown that the CDHB is transformed into Airy-related beams and the dark central spot is converted into peak intensity. The effects of the incident CDHB parameters such as the mode number N, central spot width w{sub 0} and ε as well as the phase pattern parameters of Airy transform optical system on the generated beam are analyzed in detail with numerical examples.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2010

New Developments in Femtosecond Soft X-ray Spectroscopy

Recent instrumentation developments in X-ray spectroscopy for ultra-fast time-resolved measurements with soft X-rays done in HZB Berlin during the last years are described. The significant performance improvements achieved this way are based on Fresnel diffraction from structures being fabricated on a surface of a total externally reflecting mirror. The first type of this spectrometer, an off-axis reflection zone plate, has been implemented at the BESSY Femtoslicing setup and shows on the order of 20 times higher flux in the focal plane compared to the classical grating monochromator beamline. It has proven to serve very precise experiments with a time resolution down to 100 fs on magnetic materials after optical laser pulse excitation.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2010

X-ray Phase Contrast analysis - Digital wavefront development

Optical schemes that enable imaging of the phase shift produced by an object have become popular in the x-ray region, where phase can be the dominant contrast mechanism. The propagation-based technique consists of recording the interference pattern produced by choosing one or several sample-to-detector distances. Pioneering studies, carried out making use of synchrotron radiation, demonstrated that this technique results in a dramatic increase of image contrast and detail visibility, allowing the detection of structures invisible with conventional techniques. An experimental and theoretical study of in-line hard x-ray phase-contrast imaging had been performed. The theoretical description of the technique is based on Fresnel diffraction. As an illustration of the potential of this quantitative imaging technique, high-resolution x-ray phase contrast images of simple objects will be presented.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2013

Direct and alignment-insensitive measurement of cantilever curvature

We analytically derive and experimentally demonstrate a method for the simultaneous measurement of deflection for large arrays of cantilevers. The Fresnel diffraction patterns of a cantilever independently reveal tilt, curvature, cubic, and higher order bending of the cantilever. It provides a calibrated absolute measurement of the polynomial coefficients describing the cantilever shape, without careful alignment and could be applied to several cantilevers simultaneously with no added complexity. We show that the method is easily implemented, works in both liquid media and in air, for a broad range of displacements and is especially suited to the requirements for multi-marker biosensors.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Coating considerations for mirrors of CPV devices

One of the different optical concepts for concentrator devices is to place a focussing primary mirror behind a transparent front plate. In addition (also in case of Fresnel-diffractive main optics), further 'secondary' reflectors may be used further along the beam path. Such mirrors are usually implemented as coating stacks of a highly reflective metal - usually silver - and protective layers. The protective layers are preferably designed as reflection enhancing interference stack. The design of such protective layer stacks yields two difficulties, which are addressed in this paper: (a) vacuum coating of three-dimensional parts will result in a thickness distribution and the optical design of the stack should thus be tolerant to layer thickness variations, and (b) different places of the mirror will have different angle-of-incidence of the sunlight under operating conditions. As result, the layer stack has a different design at different places of the mirror.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2010

Semiclassical estimates of electromagnetic Casimir self-energies of spherical and cylindrical metallic shells

The leading semiclassical estimates of the electromagnetic Casimir stresses on a spherical and a cylindrical metallic shell are within 1% of the field theoretical values. The electromagnetic Casimir energy for both geometries is given by two decoupled massless scalars that satisfy conformally covariant boundary conditions. Surface contributions vanish for smooth metallic boundaries, and the finite electromagnetic Casimir energy in leading semiclassical approximation is due to quadratic fluctuations about periodic rays in the interior of the cavity only. Semiclassically, the nonvanishing Casimir energy of a metallic cylindrical shell is almost entirely due to Fresnel diffraction.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Toward an integrated platform for characterizing laser-driven, isochorically heated plasmas with 1 µm spatial resolution

Warm dense matter is a region of phase space that is of high interest to multiple scientific communities ranging from astrophysics to inertial confinement fusion. Further understanding of the conditions and properties of this complex state of matter necessitates experimental benchmarking of the current theoretical models. We discuss the development of an x-ray radiography platform designed to measure warm dense matter transport properties at large laser facilities such as the OMEGA Laser Facility. Our platform, Fresnel Diffractive Radiography, allows for high spatial resolution imaging of isochorically heated targets, resulting in notable diffractive effects at sharp density gradients that are influenced by transport properties such as thermal conductivity. We discuss initial results, highlighting the capabilities of the platform in measuring diffractive features with micron-level spatial resolution.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗