3,908 research outputs found
Study of rock experiments to measure interplanetary energetic hydrogen fluxes and hydrogen fluxes during an auroral breakup
Flux, energy spectra, and pitch angle distributions of precipitated low energy hydrogen and electrons from Nike-Tomahawk auroral hydrogen experimen
Measurement of the anomalous phase velocity of ballistic light in a random medium by use of a novel interferometer
Ballistic light, i.e., radiation that propagates undeflected through a turbid medium, undergoes a small change in phase velocity and exhibits unusual dispersion because of its wave nature. We use a novel highly sensitive differential phase optical interferometer to study these previously unmeasurable phenomena. We find that ballistic propagation can be classified into three regimes based on the wavelength-to-size ratio. In the regime in which the scatterer size is comparable with the wavelength, there is an anomalous phase-velocity increase as a result of adding scatterers of higher refractive index. We also observe an anomaly in the relative phase velocity, where red light is slowed more than blue light even though the added scatterers are made of material with normal dispersion
Fourier-domain low-coherence interferometry for light-scattering spectroscopy
We present a novel method for obtaining depth-resolved spectra for determining scatterer size through elastic- scattering properties. Depth resolution is achieved with a white-light source in a Michelson interferometer with the mixed signal and reference fields dispersed by a spectrograph. The spectrum is Fourier transformed to yield the axial spatial cross correlation between the signal and reference fields with near 1 m m depth resolution. Spectral information is obtained by windowing to yield the scattering amplitude as a function of wave number. The technique is demonstrated by determination of the size of polystyrene microspheres in a subsurface layer with subwavelength accuracy. Application of the technique to probing the size of cell nuclei in living epithelial tissues is discussed
Direct measurement of spatial Wigner function with area-integrated detection
We demonstrate experimentally a novel technique for characterizing transverse
spatial coherence using the Wigner distribution function. The presented method
is based on measuring interference between a pair of rotated and displaced
replicas of the input beam with an area-integrating detector, and it can be
superior in regimes when array detectors are not available. We analyze the
quantum optical picture of the presented measurement for single-photon signals
and discuss possible applications in quantum information processing.Comment: 3 pages, REVTe
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