Broad Band Observations of Gravitationally Lensed Blazar during a Gamma-Ray Outburst
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Julian Sitarek↗
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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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Constraining the mass density of free-floating black holes using razor-thin lensing arcs
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Uddipan Banik↗
On dielectric lenses
Dielectric lens for correction of curved field lines in electromagnetic wave propagation
ELECTROMAGNETIC PROPAGATION↗
Exploring the non-Gaussianity of the cosmic infrared background and its weak gravitational lensing
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Jaemyoung (Jason) Lee↗
Collection and concentration of solar energy using Fresnel type lenses
The efficiency of collecting solar energy using a Fresnel type lens was measured for two different collectors. A flow collector utilizes the temperature difference and heat capacity in water measurements to determine the amount of absorbed energy retained from sun rays passing through the Fresnel lens. A static collector is a hollow copper box filled with vegetable heating oil for absorption of focused solar radiation.
Wilson, R. F.↗
Wide angle lenses with aspheric correcting surfaces
Refracting elements having aspheric correcting surfaces near the center of curvature are analyzed. As in the case of the Schmidt reflector, such systems can have a wide aperture and a wide field of view; in addition, they are free from obstructing surfaces. Being uncorrected for dispersion, however, the refracting systems are restricted to nearly monochromatic radiation. Typical forms of the correcting surfaces have been determined, both by third order theory and by numerical integration of exact equations.
Jones, R. T.↗
Effects of edge-rounding on geodesic lenses
A method that eliminates the need for a mathematical model is described for measuring the absolute light intensity radiated from volume chemiluminescent and fluorescent sources. This technique applies to a uniform cylindrical luminous volume, which is the geometry most often practical for the study of flowing chemiluminescent and fluorescent fluids. In this method, the necessary integration over a luminous volume is carried out experimentally, using a calibrated piston source that has as its head a disk of uniform luminosity. The relatively small total error in absolute light intensity measurements with the piston source technique represents a significant improvement over competing comparison methods. The construction of a piston source to fit the cross section of a particular cylindrical volume is straightforward, and its calibration against a standard source can be readily made while exercising normal precautions.
Wood, V. E.↗
Large multi-lensed telescope - A receiver for point sources in the sky
A large 80-in. (2-meter) multilensed computer-controlled and encoder-pointed telescope is described. It is being used as the receiver in the high-performance lunar laser ranging station on Mt. Haleakala on the island of Maui, Hawaii; however, it could also be used for other astronomical applications when the moon is not up. This telescope, which was designed for applications requiring aperture but not field, could affect the design of future very large astronomical instruments intended mainly for point-source spectroscopy and similar applications. The telescope and its performance to date are discussed.
Faller, J. E.↗
Space power system utilizing Fresnel lenses for solar power and also thermal energy storage
A solar power plant suitable for earth orbits passing through Van Allen radiation belts is described. The solar-to-electricity conversion efficiency is estimated to be around 9 percent, and the expected power-to-weight ratio is competitive with photovoltaic arrays. The system is designed to be self-contained, to be indifferent to radiation belt exposures, store energy for periods when the orbiting system is in earth shadow (so that power generation is contant), have no moving parts and no working fluids, and be robust against micrometeorite attack. No electrical batteries are required.
Turner, R. H.↗
Modulation Transfer Function (MTF) measurement techniques for lenses and linear detector arrays
Application is the determination of the Modulation Transfer Function (MTF) for linear detector arrays. A system set up requires knowledge of the MTF of the imaging lens. Procedure for this measurement is described for standard optical lab equipment. Given this information, various possible approaches to MTF measurement for linear arrays is described. The knife edge method is then described in detail.
Schnabel, J. J., Jr.↗
Is QSO 1146 + 111B,C due to lensing by a cosmic string?
A newly discovered lens candidate, QSO 1146 + 111B,C, is discussed which appears to consist of two images of equal brightness of a quasar at redshift 1.01 separated by 2.6 arcmin. If this is produced by a cosmic string, its mass per unit length is about 4.0 x 10 to the 23rd g/cm or more. This value is large enough to be interesting for string-assisted galaxy formation and near the upper limits implied by the isotropy of the cosmic microwave background and constraints on gravitational radiation.
Gott, J. R., III↗
An analytically soluble problem in fully nonlinear statistical gravitational lensing
The amplification probability distribution p(I)dI for a point source behind a random star field which acts as the deflector exhibits a I exp-3 behavior for large amplification, as can be shown from the universality of the lens equation near critical lines. In this paper it is shown that the amplitude of the I exp-3 tail can be derived exactly for arbitrary mass distribution of the stars, surface mass density of stars and smoothly distributed matter, and large-scale shear. This is then compared with the corresponding linear result.
Schneider, P.↗
The LAGEOS Lense-Thirring precession and the LAGEOS non-gravitational nodal perturbations. I
After a brief description of the experiment to detect the gravitomagnetic field using high altitude laser ranged artificial satellites, several nongravitational perturbations that affect the LAGEOS nodal longitude are studied. It is shown that the error in the calculated value of the secular nodal precession or the value of the secular nodal precession itself is, for each perturbation, less than 1 percent of the gravitomagnetic drag.
Ciufolini, Ignazio↗
An advanced space photovoltaic concentrator array using Fresnel lenses, gallium arsenide cells, and prismatic cell covers
The current status of a space concentrator array which uses refractive optics, gallium arsenide cells, and prismatic cell covers to achieve excellent performance at a very low array mass is documented. The prismatically covered cells have established records for space cell performance (24.2 percent efficient at 100 AM0 suns and 25 C) and terrestrial single-junction cell performance (29.3 percent efficient at 200 AM1.5 suns and 25 C).
O'Neill, Mark J.↗
Gravitational lenses
Recent observational and theoretical investigations of gravitational-lens phenomena are reviewed, and sample numerical data are presented in tables. Particular attention is given to luminous arcs, radio rings, galaxy-quasar associations, the problem of deriving actually or practically unique models of individual lens systems, and time delays and the Hubble constant.
Turner, Edwin L.↗
The magnification of stars crossing a caustic. I - Lenses with smooth potentials
The possibility is explored of observing highly magnified images of individual stars within the long arcs that have been observed in rich clusters of galaxies. These images appear when a star crosses a caustic of the cluster's potential. When the cluster mass is distributed smoothly, the maximum magnification reached is typically of the order of 10 to the 7th. The star's image appears suddenly and reaches the maximum magnification in a few hours; then the magnification decreases slowly as the inverse of the square root of the time. This can also occur in the reverse order in time. For typical arcs, stars with bolometric luminosities of around 300 solar luminosities reach a maximum visual apparent magnitude of about 25. If brighter events are detected, the rate of detection is of the order of one every five years, for every arc intersecting a caustic. If the source galaxy is forming stars with a Saltpeter IMF, the probability that a 30-solar-mass star is magnified to a magnitude of 28 at any time is of the order of 20 percent.
Miralda-Escude, Jordi↗
Adjusting Curvatures Of Large Mirrors And Lenses
Actuators apply stresses to generate distortions counteracting undesired distortions in technique for adjusting curvature of large focusing mirror or lens. Motor-and-gear assemblies under remote control vary squeeze of ring clamp and push or pull of hollow shaft to make fine adjustments in curvature of mirror. Applicable to large astronomical-telescope mirrors with diameters of 60 cm or more.
Birnbaum, Morris M.↗
Searching gamma-ray bursts for gravitational lensing echoes - Implications for compact dark matter
The first available 44 gamma-ray bursts (GRBs) detected by the Burst and Transient Source Experiment on board the Compton Gamma-Ray Observatory have been inspected for echo signals following shortly after the main signal. No significant echoes have been found. Echoes would have been expected were the GRBs distant enough and the universe populated with a sufficient density of compact objects composing the dark matter. Constraints on dark matter abundance and GRB redshifts from the present data are presented and discussed. Based on these preliminary results, a universe filled to critical density of compact objects between 10 exp 6.5 and 10 exp 8.1 solar masses are now marginally excluded, or the most likely cosmological distance paradigm for GRBs is not correct. We expect future constraints to be able either to test currently popular cosmological dark matter paradigms or to indicate that GRBs do not lie at cosmological distances.
Nemiroff, R. J.↗