16,032 research outputs found
Three Dimensional Imaging of the Nucleon
We study the Wigner distributions of quarks and gluons in light-front dressed
quark model using the overlap of light front wave functions (LFWFs). We take
the target to be a dressed quark, this is a composite spin state of
quark dressed with a gluon. This state allows us to calculate the quark and
gluon Wigner distributions analytically in terms of LFWFs using Hamiltonian
perturbation theory. We analyze numerically the Wigner distributions of quark
and gluon and report their nature in the contour plots. We use an improved
numerical technique to remove the cutoff dependence of the Fourier transformed
integral over .Comment: 7 pages, 2 figures, Prepared for Proceedings of Light Cone 2017,
18-22 Sept, University of Mumbai, India. To appear in FB
Three dimensional imaging of short pulses
We exploit a slightly noncollinear second-harmonic cross-correlation scheme
to map the 3D space-time intensity distribution of an unknown complex-shaped
ultrashort optical pulse. We show the capability of the technique to
reconstruct both the amplitude and the phase of the field through the coherence
of the nonlinear interaction down to a resolution of 10 m in space and 200
fs in time. This implies that the concept of second-harmonic holography can be
employed down to the sub-ps time scale, and used to discuss the features of the
technique in terms of the reconstructed fields.Comment: 16 pages, 6 figure
Three-dimensional imaging of random radiation sources
A method to image random three-dimensional source distributions is proposed. We show that, by using a Michelson stellar interferometer in a prescribed fashion, one is able to measure a special form of a three-dimensional degree of coherence. The inverse Fourier transform of this coherence function yields the three-dimensional intensity distribution of the source as seen from the paraxial far zone
Three-dimensional Imaging of Microstructure in Gold Nanocrystals
X-ray diffraction using a coherent beam involves the mutual interference among all the extremities of small crystals. The continuous diffraction pattern so produced can be phased because it can be oversampled. We have thus obtained three-dimensional images of the interiors of Au nanocrystals that show 50 nm wide bands of contrast with f111g orientation that probably arise from internal twinning by dynamic recrystallization during their formation at high temperature
Three-dimensional imaging of direct-written photonic structures
Third harmonic generation microscopy has been used to analyze the morphology
of photonic structures created using the femtosecond laser direct-write
technique. Three dimensional waveguide arrays and waveguide-Bragg gratings
written in fused-silica and doped phosphate glass were investigated. A
sensorless adaptive optical system was used to correct the optical aberrations
occurring in the sample and microscope system, which had a lateral resolution
of less than 500 nm. This non-destructive testing method creates volume
reconstructions of photonic devices and reveals details invisible to other
linear microscopy and index profilometry techniques.Comment: 8 pages, 3 color figures, 2 hyper-linked animation
Single shot three-dimensional imaging of dilute atomic clouds
Light field microscopy methods together with three dimensional (3D)
deconvolution can be used to obtain single shot 3D images of atomic clouds. We
demonstrate the method using a test setup which extracts three dimensional
images from a fluorescent Rb atomic vapor.Comment: 10 pages, 5 figure
Measuring every particle's size from three-dimensional imaging experiments
Often experimentalists study colloidal suspensions that are nominally
monodisperse. In reality these samples have a polydispersity of 4-10%. At the
level of an individual particle, the consequences of this polydispersity are
unknown as it is difficult to measure an individual particle size from
microscopy. We propose a general method to estimate individual particle radii
within a moderately concentrated colloidal suspension observed with confocal
microscopy. We confirm the validity of our method by numerical simulations of
four major systems: random close packing, colloidal gels, nominally
monodisperse dense samples, and nominally binary dense samples. We then apply
our method to experimental data, and demonstrate the utility of this method
with results from four case studies. In the first, we demonstrate that we can
recover the full particle size distribution {\it in situ}. In the second, we
show that accounting for particle size leads to more accurate structural
information in a random close packed sample. In the third, we show that crystal
nucleation occurs in locally monodisperse regions. In the fourth, we show that
particle mobility in a dense sample is correlated to the local volume fraction.Comment: 7 pages, 5 figure
General theorem of spatial coherence: application to three-dimensional imaging
Three-dimensional imaging of incoherent light sources by the Michelson stellar interferometer is considered. When the interferometer’s pinholes are arranged properly, its output result is equivalent to a two-dimensional Fourier hologram that stores information about the source object’s three-dimensional intensity distribution
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