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Topic: Interferometric visibility

	Visibility - Wikipedia, the free encyclopedia
		Meteorological visibility refers to transparency of air: in dark, meteorological visibility is still the same as in the same air in daylight.
		Visibility is also used in water, as a measure of turbidity.
		Also, interferometric visibility is used to quantify interference contrast in optics.
	en.wikipedia.org /wiki/Visibility (423 words)

	Interferometric visibility - Wikipedia, the free encyclopedia
		The interferometric visibility (also known as "interference visibility" or "fringe visibility" or just "visibility") quantifies the contrast of interference in any system which has wave-like properties, such as optics, quantum mechanics, water waves, or electrical signals.
		Under these circumstances, the interferometric visibility is also known as the "Mach-Zehnder visibility" or the "fringe visibility." For this type of interference, the sum of the intensities (or powers) of the two interfering waves equals the average of the fringes.
		In this sense, the visibility is a measure of the coherence between two optical fields.
	en.wikipedia.org /wiki/Interferometric_visibility (401 words)

	[No title] (Site not responding. Last check: 2007-11-04)
		The antennas commonly used for this purpose are antennas having a wide field of view (70-80 degrees of visibility cone), which are often not suitable for interferometric measurements in terms of thermal sensitivity, phase measurement stability and coupling with satellite structure.
		The interferometer model 2 provides the expected interferometric measurements and their derivatives on the basis of the satellite position, of the calibrated misalignments and of the estimated attitude.
		The inclusion of the interferometric measurements derivatives in the residual vector of the observer is suggested by the time variability of the measurement matrix of the system, due to the motion of the source satellites (e.
	www.wipo.int /cgi-pct/guest/getbykey5?KEY=00/22452.000420&ELEMENT_SET=DECL (2201 words)

	ILL ANNUAL REPORT 2002
		During the last twenty years various interferometric experiments with thermal and very cold neutrons were performed.
		Interferometric measurements give direct experimental access to the complete coherence function of the wavefield, the amplitude and the relative phase of the transmitted and the scattered beam.
		The maximum visibility of the inference fringes is 21%.
	www.ill.fr /AR-02/site/areport/fb_112.htm (721 words)

	[No title]
		The `Ohana concept considers interferometric coupling of 3 to 10 meter class telescopes of Mauna Kea taking advantage of two technological breakthroughs: adaptive optics and coherent transport of light with single mode optical fibers.
		Significant results can be obtained by obtaining visibilities in H band and Pa{beta}; a moderate spectral resolution is needed for the determination of the size of the BLR.
		The required accuracy on the visibility is 1% and there are half a dozen candidates within 10 pc.
	www.cfht.hawaii.edu /~lai/OHANA/summary-2nd.txt (2277 words)

	Development of radio interferometry
		The complex visibility must be known at all points in a n×m rectangular array in the u-v plane for a portion of the sky to be mapped with resolution equivalent to n×m pixels.
		For direct measurement of the complex visibility at a rectangular array of points in the u-v plane a large number of different baselines is required.
		As the phase of each complex visibility measurement cannot be determined with a very long baseline the symmetry of the corresponding contribution to the source brightness distributions is not known.
	www.geocities.com /CapeCanaveral/2309/page3.html (1733 words)

	nbCalib -- Narrow-band Interferometric Visibility Calibration (Site not responding. Last check: 2007-11-04)
		The reader unfamilier with the use of terms like interferometric visibility and interferometric resolution is refered to any standard interferometric textbook such as Thompson, Moran, and Swenson, the NRAO Imaging Summer School Notes, or lecture notes from the Michelson Summer School.
		The fundamental purpose of nbCalib is to estimate the squared visibility modulus (herein refered to a visibility amplitude or visibility) on a target as measured by an idealized interferometer V^2_target based on the visibility amplitude measurement made by the interferometer V^2_meas.
		Therefore, the job of nbCalib is to estimate the system visibility at the time of the target scan by analyzing available calibration measurements, and then to apply (in the sense of Eq 2.2) this system visibility model it to the measured target visibility at epoch to estimate the idealized target visibility at epoch.
	msc.caltech.edu /software/nbCalib (5797 words)

	Stellar surface structure
		Figure 3 shows the interferometric signal (visibility magnitude) which can be expected for a relatively quiet (solar-type) and an active star.
		It is important to notice that the signatures in the visibility functions occur at high angular frequencies and have small magnitudes.
		The primary goal of an interferometric survey of the local neighbourhood will be to determine the frequency of occurrence of these hotspots as a function of type and luminosity class.
	www.eso.org /projects/vlti/science/node6.html (1203 words)

	Jeff Meisner's Interferometry Page
		Visibilities beyond the first null were obtained for several objects, thus directly constraining the magnitude of limb-darkening in these cases.
		The visibilities of the emission lines indicate that the spatial extent in the lines (50 to 60 milli-arcseconds) is larger than in the continuum (35 to 45 milli-arcseconds).
		The measurement of fringe visibility (correlation) in a long baseline optical/infrared astronomical interferometer may be performed through a coherent integration of noisy data if a measurement of the phase producing the interference is available.
	www.strw.leidenuniv.nl /~meisner (4175 words)

	A Comparative Study of Speckle Interferometric Techniques (Site not responding. Last check: 2007-11-04)
		Subtractive speckle interferometric techniques, such as electronic speckle pattern interferometry (ESPI) and shearography, have been conventionally employed for full-field nondestructive evaluation of diffuse surfaces.
		Furthermore, quantitative comparisons are made based on the fringe visibility (a measured relative contrast parameter associated with detectability) of defect images acquired under controlled in-plane translation noise.
		Owner-Petersen, M., "Decorrelation and fringe visibility: on the limiting behavior of various electronic speckle-pattern correlation interferometers," Journal of the Optical Society of America A, vol.
	www.cnde.iastate.edu /qndedatabase/Vol.14A/p0393-0400.html (347 words)

	Interferometric Sensor Measuring and Modeling Environment
		To the scientist astronomical interferometers provide a phase (delay line position) and amplitude (visibility) measurements at a given baseline separation and orientation on stars.
		In the ideal case, the visibility of a star is related to its structure.
		A point source will give high visibility while an extended source such as a giant star, a dust enshrowded star, or a close binary star will give low visibility.
	www2.jpl.nasa.gov /iae/highlights/yr-end99/Interferometric/interferometric.htm (1328 words)

	[No title] (Site not responding. Last check: 2007-11-04)
		The convolutional gridding used to interpolate the irregularly sampled data onto a rectangular grid is examined, including aliasing of sources outside the primary field of view.
		Furthermore, how the visibility samples collected by an interferometric array can be used to produce a high quality image of the sky is described.
		These non-linear methods try to create estimates of the visibility function at positions in the Fourier plane where it is not measured.
	www.ees.nmt.edu /Geop/Classes/GEOP505/Docs/student_abstracts_2004.html (638 words)

	Optical and Infrared Interferometric Imaging
		High resolution astronomical imaging from ground-based telescopes has long been known to be severely complicated by the effects of atmospheric turbulence on the wavefront of the incoming radiation.
		Thus the apparently dissimilar efforts to achieve ground-based diffraction-limited optical imaging with both filled aperture telescopes and discrete element interferometers are unified in their exploitation of the closure phase principle to solve the phase corruption problem.
		The scientific objectives of applying interferometric techniques to filled-aperture telescopes at optical and infrared wavelengths are based on the desire for complete structure information in astronomical images, up to the diffraction limit of the telescope.
	www.srl.caltech.edu /compastro/bispectrum_report.html (2974 words)

	VLTI Baseline Preparation Help Page
		It uses a model of the VLTI and of various instruments to assess the fringe visibility, given the observed bandpass, the geometry, spectrum and coordinates of the target and the time at which the observations are to be made.
		Optimal pixel scales are close to the resolution limit of the system determined by the baseline and the observation wavelength (typical values for MIDI at 10 microns with the UT1-UT3 or UT2-UT3 baselines range about 20 mas).
		The interferometric visibility is normalised between 0 and 1 and this visibility can be seen against time as the observation progresses.
	www.eso.org /observing/etc/doc/vlti/helpvlti.htm (1271 words)

	The CARMA Data Viewer
		CDV was designed to solve the problem of a common data viewer for interferometric observatories (the Berkeley-Illinois-Maryland Association array and the Owens Valley Radio Observatory array) with differing visibility data (amplitude and phase) formats and differing hardware and technical specifications.
		A visibility is a complex number representing the amplitude and phase correlation between a pair of antennas (a baseline).
		The visibility data may be multi-channel or single channel and are tagged with frequency, position, velocity, and time information.
	www.adass.org /adass/proceedings/adass00/P1-49/P1-49.html (1058 words)

	INFRARED GROUP OF THE ROME ASTRONOMICAL OBSERVATORY
		MIDI observations of the circumstellar environment of Herbig Ae/Be stars: we are comparing MIDI visibility spectra with models for the circumstellar structure of these young stars in order to constraints their geometry.
		We are now modelling the two different scenarios to derive the corresponding visibilities and visibility contrast with respect to the continuum emission.
		An example is given in the following figures where the visibility at the wavelength of the Brackett gamma line (2.16 µ m) is compared with that in the adjacent continuum due to the circumstellar disk and the star, for the two cases of wind and accretion gas emission.
	www.mporzio.astro.it /~bruni/interferometry.html (627 words)

	Are dust shell models well-suited to explain interferometric data of late-type stars in the near-infrared?
		interferometric data were also taken into account to further constrain the models.
		For all three AGB stars, the photosphere and dust shell model is consistent with the multi-wavelength photometric data.
		, cannot explain the visibility data in L; an additional source of model opacity, possibly related to a gas component, is needed in L to be consistent with the visibility data.
	www.edpsciences.org /articles/aa/abs/2004/16/aa3722/aa3722.html (435 words)

	OHANA summary
		Phase II: first coupling of a pair of telescopes leading to fringes acquisition, visibility measurements and scientific impact (2002- mid 2003).
		The conceptual design of the injection module was overviewed and the use of such a device as a diagnostic tool for adaptive optics was reviewed and offered for characterisation for existing or planned AO systems.
		The use of single mode fibers for beam transport over hectometric distances in the visible and near infrared has been demonstrated in laboratory experiments in Japan (MIRA) as well as in France (IRCOM), and will be pursued at Observatoire de Paris for K band fibers.
	www.cfht.hawaii.edu /~lai/OHANA/summary-2nd.html (1931 words)

	[No title]
		A well-defined expression for two-particle interference visibility was introduced for the first time.
		- The two-particle visibility expression was related to degree of entanglement by A. Shimony, Ann.
		A complementary relationship between path distinguishability and interference visibility for one-particle interference was predicted using an improved measure of path distinguishability for a broad range of quantum states.
	math.bu.edu /people/jaeger/spinoffs.html (1312 words)

	Random Groups
		On application is for uv interferometric visibility data; in fact, random groups are sometimes referred to as UV FITS.
		Consider a set of weighted complex fringe visibilities for the four Stokes polarizations at a sequence of evenly spaced frequencies.
		The points along the frequency axis are evenly spaced, and the fringe visibility and Stokes axes can both be handled by using ``evenly spaced'' integer index points to represent the separate components -- real, complex, and weight -- for the visibility and the four Stokes parameters.
	www.astro.psu.edu /xray/fits/users_guide_V4.0/node29.html (632 words)

	wbCalib -- Wide-band Interferometric Visibility Calibration (Site not responding. Last check: 2007-11-04)
		In particular it is important (particularly for radio interferometrists) to note that wbCalib deals with the calibration of normalized squared visibility modulus, which optical interferometrists notationally describe as V^2, and often call squared visibilty amplitude, or visibility amplitude, or sometimes (unfortunately) just visibility.
		The fundamental purpose of wbCalib is to estimate the squared visibility modulus (herein refered to a visibility amplitude or visibility) on a target as measured by an idealized interferometer V^2_target based on the visibility amplitude measurement made by the interferometer V^2_meas.
		Therefore, the job of wbCalib is to estimate the system visibility at the time of the target scan by analyzing available calibration measurements, and then to apply (in the sense of Eq 2.2) this system visibility model it to the measured target visibility at epoch to estimate the idealized target visibility at epoch.
	msc.caltech.edu /software/wbCalib (5706 words)

	Introduction
		An interferometric array samples the complex visibility function V(u,v) of the sky at points in the u,v plane.
		Under approximations that are valid for a sufficiently small sources in an otherwise empty sky, the visibility function V(u,v) is related to the angular distribution of the source intensity I(l,m) (multiplied by the primary beam of the array elements) through a two-dimensional Fourier transform:
		Instead, I(l,m) must be estimated either from a model with a finite number of parameters, or from a non-parametric approach.
	www.cv.nrao.edu /~abridle/deconvol/node3.html (486 words)

	Noise maps in aperture synthesis radiometric images due to cross-correlation of visibility noise
		This study deals with the calculation of the distribution of radiometric errors (“noise maps”) in the images formed by a two-dimensional aperture synthesis radiometer, specifically the MIRAS and the HUT-2D instruments.
		The HUT-2D is a U-shaped airborne interferometric radiometer under development by the Helsinki University of Technology.
		The study focuses on the known fact that the cross-correlation of the visibility noise does depend on the shape of the sensor.
	www.agu.org /pubs/crossref/2003/2002RS002707.shtml (232 words)

	[No title]
		216, 165 (2003) Visibility The classic measurement of the visibility of interference phenomena is of the form EMBED Equation.3 where EMBED Equation.3 , EMBED Equation.3 are the maximum and minimum of the corresponding distribution EMBED Equation.3 .
		35, 8805 (2002) We have extended this idea of visibility as a distance to the case of multi-particle interference, normally in the form of a probability EMBED Equation.3 of coincidence of the detection of particles at the output of an interferometer, where EMBED Equation.3 represent the internal phases of the interferometer.
		With this approach we have demonstrated that for two particles the multi-particle visibility and the individual visibilities are complementary observables (when one increases the other decreases and vice-versa).
	www.ucm.es /info/gioq/investigacion/subjects/polarizationvisibility.doc (2084 words)

	Low-cost Interferometric TDM technology Paper
		First, the requisite elements of interferometric interrogation are defined for a single channel sensor.
		The key components of an interferometric interrogator are shown in figure 1 for a single, remote fiber interferometric sensor.
		The PDR design developed for interferometric interrogation is based on a 1X3 or 3X3 fused biconic taper coupler with short leads to polarized photodiodes and is depicted in figure 7.
	www.optiphase.com /low_cost_tdm.htm (3565 words)

	Special Features of ASAR
		The along-track interferometric method is most often used when detecting relatively fast motion, such as ocean currents.
		The temporal separation in repeat-pass interferometry of days, months, or even years, can be used to advantage for long term monitoring of geodynamic phenomena, in which the target has changed position at a relatively slow pace.
		In particular, since ASAR can provide higher off-nadir angles than was the case with the ERS-1/2 sensors, the problems of layover will be reduced, thereby enhancing the interferometric visibility of steeper slopes.
	envisat.esa.int /dataproducts/asar/CNTR1-1-5.htm (7809 words)

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