Optical interferometry

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Topic: Optical interferometry

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	Optical interferometry - Wikipedia, the free encyclopedia
		Optical interferometry is a technique of interferometry combining light from multiple sources in an optical instrument in order to make various precise measurements.
		Of the uses of optical interferometry mention should be made of the Michelson-Morley experiment, a test of the Special Theory of Relativity.
		Monnier, Optical interferometry in astronomy, Reports on Progress in Physics, 66, 789-857, 2003 IoP.
	en.wikipedia.org /wiki/Optical_interferometry (1107 words)

	Optical coherence tomography - Wikipedia, the free encyclopedia
		The optical carrier is due to the Doppler effect resulting from scanning one arm of the interferometer, and the frequency of this modulation is controlled by the speed of scanning.
		Optical coherence tomography (OCT) is an interferometric, non-invasive optical tomographic imaging technique offering millimeter penetration (approximatelly 2-3 mm in tissue) with sub-micrometre axial and lateral resolution.
		In frequency domain OCT the broadband intereference is acquired with spectrally separated detectors (either by encoding the optical frequency in time with a spectrally scanning source or with a dispersive detector, like a grating and a linear detector array).
	en.wikipedia.org /wiki/Optical_coherence_tomography (2141 words)

	NIST: Quantum Metrology Group - X-ray Interferometry
		X-ray interferometry uses the interference of two x-ray beams to precisely measure optical constants, or (by moving components of the interferometer) to measure displacement with picometer precision.
		The results should include a new implementation of combined x-ray and optical interferometry, pairwise intercomparisons that have not been previously undertaken, and technology developments reducing periodic errors in Michelson interferometry.
		X-ray interferometry (XRI) was invented by Bonse and Hart at Cornell University in 1965 [1].
	physics.nist.gov /Divisions/Div842/Gp5/admd.html (1280 words)

	Opticon - Interferometry
		The objective of the Interferometry Forum is to bring optical interferometry to main stream astronomy and enable the Candidate Countries of central Europe to participate fully in technical and scientific developments in optical interferometry.
		European Exchange Visitors Programme in Optical Interferometry: Funding (travel and accommodation) will be made available for visits of researchers from one of the participants to an institute of his/her choice (but within the European Community) to perform collaborative work on one of the active topics of the European Interferometry Initiative.
		The specific objectives of this activity are: (1) to exploit the scientific opportunities of the new facilities; (2) to integrate interferometry with more traditional astronomical techniques and make interferometry accessible to non-specialists; (3) to develop a long-term scientific perspective for optical / infrared interferometry well into the next decade.
	www.astro-opticon.org /networking/interferometry.html (382 words)

	Untitled Document
		Optical interferometry proved to be a quantum leap forward in the field of astrometry for the angular measurement of stars.
		Since then, optical interferometers have employed the technique of using two mirrors separated by some distance to create a mirror with an effective aperture that is not a function of the diameter of the mirror, but of the size of the baseline separating the two mirrors.
		The ability of optical telescopes to resolve fine detail is limited by the wavelength of the light under study and by the size or diameter of the lens or mirror that collects the light.
	www1.wcf.net /~radduci/Papers/606-p.html (5460 words)

	19112.030306&ELEMENT_SET=DECL
		The interferometry method includes directing the first beam from a direction parallel to the direction of the portion of the first beam contacting the first object to a direction that is parallel to the portions of the second path passing through the region.
		The interferometry system includes optics to redirect the measurement beam after the first pass and before the second pass so that during the second pass, a portion of the measurement path traversed by the measurement beam propagating from the measurement object toward the interferometer remains the same independent of a movement of the measurement object.
		The interferometry method includes redirecting the measurement beam after the measurement beam completes the at least two passes and before overlapping with the other beam so that when the measurement beam overlaps with the other beam, the measurement beam propagates in a direction that remains constant relative to a propagation direction of the other beam.
	www.wipo.int /cgi-pct/guest/getbykey5?KEY=03/19112.030306&ELEMENT_SET=DECL (12544 words)

	Early optical interferometry
		With the optical arrangement of Figure 2 a large objective lens or mirror is required for measurements with large slit separations and much of the light that passes through the slits in the aperture mask is wasted.
		Instead, the appropriate difference in optical path length from the detectors to each of the slits could be produced by careful adjustment of the mirror positions.
		By varying the optical path length of one of the beams it is possible to calculate the complex visibility with just one detector.
	www.geocities.com /CapeCanaveral/2309/page2.html (1231 words)

	Astronomical Optical Interferometry
		Fizeau first suggested that optical interferometry might be used for the measurement of stellar diameters at the Academie des Sciences in 1867
		This report documents the development of optical interferometry and provides a physical explanation of the processes involved.
		Other recent reviews of optical interferometry are listed as references 30-33.
	www.geocities.com /CapeCanaveral/2309/page1.html (364 words)

	Science News: Taking the measure of the stars - optical interferometry
		Interferometry began as a technique inoptical laboratories, using visible light, but its most widespread use in astronomy so far has been in the radio range.
		In the century and a half since interferometry was developed in the laboratory, astronomers working with visible light have not been able to utilize it to any great extent.
		This produces what we see as stellar twinkling, and it destroys the correlations on which interferometry depends unless the two receivers are under the same isoplanatic patch, the area in which the atmospheric refraction changes uniformly.
	www.findarticles.com /p/articles/mi_m1200/is_v131/ai_4610623 (1466 words)

	Interferometry
		The field of optical interferometry was regarded as a more difficult than radio interferometry and limited in application until recently.
		MWO – Education – Presentations – Interferometry is a useful article from the Mount Wilson Observatory educational team covering the basic idea of wave interference, the Michelson-Morely experiment and the application of interferometry to astronomy.
		In interferometry, the resolution then is not determined by the size of individual collectors such as mirrors or radio dishes but rather by the maximum separation of the collecting elements.
	outreach.atnf.csiro.au /education/senior/astrophysics/interferometry.html (1842 words)

	Optical Interferometry
		Interferometry uses the constructive and destructive interference of radiation to determine the spatial properties of the source of the radiation.
		But seeing limitations to the sensitivity of optical telescopes made an interferometric array of large optical telescopes ineffective, and so past efforts were limited to building small dedicated optical interferometers.
		With the ability to correct for the atmospheric seeing effects and the fact that optical telescopes tend to be clustered at a few good observing sites, the coupling of large telescopes into an interferometric array now appears to be feasible.
	www.pha.jhu.edu /~jlotz/aoptics/node5.html (537 words)

	Laser Focus World - Optical interferometry analyzes the body
		Optical interferometry, traditionally the toolbox of the research laboratory, can assist in the study of several parts of the body, including the hip, jaw, and cornea.
		Using phase-shifted speckle interferometry, it was possible to acquire the horizontal and vertical in-plane images of the head and shaft of the femur.
		Some may argue that you don't have to be an optical engineer to determine this, but not only have we proven the bra does not work, but in reverse engineering the load case, we have been able to design support garments that genuinely do work.
	lfw.pennnet.com /Articles/Article_Display.cfm?Article_ID=97961 (1548 words)

	Curious About Astronomy: Is it possible for amateurs to do optical interferometry?
		One of the problems with optical interferometry is that the wavelengths are very small, so that one is talking of doing things very precisely.
		I know basically what Optical Interferometry is (combining the signal of two or more telescopes to synthesize a larger scope) but can't find any technical details on how it is achieved.
		So, interferometry is not as simple as taking two images from telescopes and combining them.
	curious.astro.cornell.edu /question.php?number=179 (427 words)

	Optical Astronomy
		CHARA research is focused on the development of astronomical long-baseline optical/infrared interferometry and the application of interferometry to high resolution observations leading to the determination of the astrophysical properties of stars.
		It is aimed at the broadest possible astrophysical exploitation of optical interferometry using a modest baseline length.
		The Vainu Bappu Observatory (VBO) is the main optical observatory of the Indian Institute of Astrophysics (IIA), and is located in the picturesque neighbourhood of the village of Kavalur in the state of Tamil Nadu.
	www.cv.nrao.edu /fits/www/yp_optical.html (11715 words)

	ScienceWeek
		The implementation of interferometry in optical astronomy began more than a century ago with the work of Fizeau (1868).
		Akeson, R., M. Swain, and M. Colavita, 2000, in Interferometry in Optical Astronomy, Proceedings of SPIE No. 4006, edited by P. Lena and A. Quirrenbach (SPIE, Bellingham), p.
		The crystalline fraction and grain size of these films determines electronic and optical properties; the nanocrystal nucleation mechanism, which dictates the final film structure, is governed by the interactions between the hydrogen atoms of the plasma and the solid silicon matrix.
	scienceweek.com /2002/sw020906.htm (11068 words)

	James C. Wyant - Meeting Papers
		Abstract: The largest limitation of phase-shifting interferometry for optical testing is the sensitivity to the environment, both vibration and air turbulence.
		Computer generated holograms are now widely used in the testing of aspheric optical elements and it is expected that their use in aspheric testing will greatly increase the next few years as the superb measurement capability of CGHs are better appreciated by more optical manufacturing personnel.
		This talk discusses the use of simultaneous phase-shifting interferometry and pixelated phase-mask dynamic interferometry to reduce the effects of the environment on the measurement.
	www.optics.arizona.edu /jcwyant/Meeting_papers.htm (1077 words)

	What is optical interferometry
		In optical interferometry, the combination of light waves upon entering the interferometer is controlled by carefully positioned primary mirrors within the instrument.
		Optical interferometers are used primarily for the measurement of the angular diameters of stars and binary star orbits.
		According to Hajian and Armstrong, the central concept at work in interferometer technology is the combination of two nearly identical signals to produce interference, thereby yielding information not given by either signal individually.
	www.owlnet.rice.edu /~lesleym/whatisit.htm (258 words)

	Publications Related to the NPOI
		"Astrometry with Optical Interferometers," Hughes, J.A., and Hutter, D.J. 1990, in Amplitude and Intensity Spatial Interferometry, ed.
		"Coherent Integration Using Phase Bootstrapping," Hummel, C. A., Mozurkewich, D., Benson, J. and Wittkowski, M. 2003, in Interferometry for Optical Astronomy II, ed.
		"Diameters of Delta Cephei and Eta Aquilae Measured with the Navy Prototype Optical Interferometer", Armstrong, J.T., Nordgren, T.E., Germain, M.E., Hajian, A.R., Hindsley, R.B., Hummel, C.A., Mozurkewich, D., and Thessin, R.N. 2001, Astron.
	www.nofs.navy.mil /projects/npoi/bibliog.htm (2082 words)

	US Government Sales::Interferometry and Synthesis in Radio Astronomy, 2nd Edition
		* Related techniques: intensity interferometry, moon occultations, antenna holography, and optical interferometry
		Interferometry and Synthesis in Radio Astronomy, Second Edition is comprehensive in that it provides an excellent overview of most radio astronomical instrumentation and techniques.
		In this Second Edition of Interferometry and Synthesis in Radio Astronomy, three leading figures in the development of large imaging arrays, including very-long-baseline interferometry (VLBI), describe and explain the technology that provides images of the universe with an angular resolution as fine as 1/20,000 of an arcsecond.
	gov.wiley.com /WileyCDA/WileyTitle/productCd-0471254924.html (290 words)

	Astronomical interferometry,from the visible to sub-mm waves
		These facilities will broaden the scope of optical and infrared interferometry by providing sufficient sensitivity to observe rather faint stars and even some extragalactic objects, by offering a suite of beam combiners and detectors covering a wide wavelength range, and by making a fairly complicated technique more accessible to a broad users’ community.
		Interferometry has been used to infer the distance of a nova explosion, and of Galactic Cepheid stars.
		ALMA will be complementary to large optical telescopes by giving us a view of cold objects and those regions of the universe that are hidden from our view by large amounts of dust.
	www.europhysicsnews.com /full/12/article13/article13.html (2194 words)

	Phase Modulation in High-resolution Optical Interferometry
		An interferometer prototype, illuminated by a beam thus modulated, was constructed and coupled to an X-ray interferometer to compare the optical and X-ray interferometric measurement values of sub-nanometre displacements.
		The measurement of nanometre displacements with picometre resolution has been made possible by a phase-modulation recovery scheme applied to an optical Michelson interferometer using polarization encoding.
		Journal of Physics B: Atomic, Molecular and Optical Physics
	stacks.iop.org /0026-1394/28/455 (262 words)

	bibliography.oir
		The spectroscopic binary eta Andromedae: determination of the orbit by optical interferometry.
		The asymmetric envelope of gamma Cassiopeiae observed with the Mk III optical interferometer.
		Observations fo Nova Cygni 1992 with a long-baseline optical interferometer.
	astron.berkeley.edu /~ay203/week10/bibliography.oir (1076 words)

	Astronomical Optical Interferometry
		Michelson stellar interferometry achieves milli-arcsecond optical resolution with ground-based telescopes.
		After seven years of successful scientific use of the Mark III Optical Interferometer to achieve 2-5 milli-arcsecond resolution for stellar imaging and astrometry, we have now built and are using a new, larger optical interferometer-the Navy Prototype Optical Interferometer-which has larger apertures and baseline lengths of up to 435 meters.
		This instrument is a major improvement in both sensitivity and resolution and it will soon be the highest spatial resolution astronomical instrument in use at any frequency.
	www4.nationalacademies.org /pga/rap.nsf/ByTitle/64.15.06.B2663?OpenDocument (185 words)

	Alibris: interferometry
		When the first edition of "Optical Interferometry" was published, interferometry was regarded as a rather esoteric method of making measurements, largely confined to the laboratory.
		The field of atom interferometry has expanded rapidly in recent years, and today's research laboratories are using atom interferometers both as inertial sensors and for precision measurements.
		In this new edition of Holographic and Speckle Interferometry the authors have taken the opportunity to expand considerably the material on applications and to include a more coherent description of a wider range of such applications.
	www.alibris.com /search/books/subject/interferometry (893 words)

	Growth of Solutal Ice Dendrites Studied by Optical Interferometry
		Optical interferometry was used to study ice dendrite growth in a homologous series of sugar solutions, chosen in order to probe the effect of solute diffusion coefficient on solutal ice dendrite growth.
		Different values were measured when the dendrites were formed in an imposed temperature gradient, which was ascribed to the increased importance of nonequilibrium effects in these cases.
		Solute concentration fields, three-dimensional dendrite morphologies, and dendrite growth velocities were measured, and the results were compared with predictions from the modified Ivantsov and solvability theories of dendrite growth.
	pubs.acs.org /cgi-bin/abstract.cgi/cgdefu/2002/2/i01/abs/cg0155604.html (201 words)

	POINTS Abstracts
		POINTS (Precision Optical INTerferometry in Space) is a design concept for an astrometric interferometer originally conceived as a means of performing the light deflection experiment of general relativity to second order.
		POINTS (Precision Optical INTerferometry in Space) would measure the angular separation of two stars separated by about 90 deg on the sky with a nominal measurement error of 5 microarcseconds (uas).
		POINTS, an astrometric optical interferometer with a nominal measurement accuracy of 5 microarcseconds for the angle between a pair of stars separated by about 90 deg, is presently under consideration.
	cfa-www.harvard.edu /~reasen/POINTS-abstracts.html (2554 words)

	Welcome Interference
		optical interferometer" with the resolving power of a huge single telescope 85 meters wide -- nearly the size of a football field.
		On Monday, March 12, 2001, starlight from HD61294, a faint star in the constellation Lynx, was captured by both Keck telescopes and transported across a sophisticated optical system spanning the 85 meters (275 feet) separating the two telescopes.
		-- this future space interferometry mission will look for infrared radiation from Earth-like planets orbiting other stars.
	science.nasa.gov /headlines/y2001/ast15mar_1.htm (974 words)

	Numerical dispersion compensation for Partial Coherence Interferometry and Optical Coherence Tomography
		Here we present a numerical dispersion compensation technique for Partial Coherence Interferometry (PCI) and Optical Coherence Tomography (OCT) based on numerical correlation of the depth scan signal with a depth variant kernel.
		Fercher, C. Hitzenberger, M. Sticker, R. Zawadzki, B. Karamata, T. Lasser, "A new dispersion compensation technique for Partial Coherence Interferometry (PCI) and Optical Coherence Tomography (OCT)," Proc SPIE 4431 (to be published).
		Schmitt and G. Kumar, "Optical scattering properties of soft tissue: a discrete particle model," Appl.
	www.opticsexpress.org /abstract.cfm?URI=OPEX-9-12-610 (434 words)

	VLTI Workshop on optical/IR interferometry
		The second part (2 days) will be organized as a joint workshop between the European Interferometry Initiative (EII) and ESO on "2nd Generation VLTI Instrumentation".
		The EII Consortium (http://amstel.strw.leidenuniv.nl/~eurinterf) regroups European scientists promoting Interferometry both from the scientific and technical/instrumental point of view
		Investigations are now enabled on a wealth of astrophysical sources with unprecedented levels of angular resolution and sensitivity, producing a considerable body of new, exciting scientific results.
	www.eso.org /gen-fac/meetings/vltiws05 (687 words)

	Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations
		The optical interferometer is a reliable gas analytical tool capable of yielding accurate results in binary mixtures, and the deviations from linearity of the data for index of refraction vs. composition can be adequately explained from molar refraction theory and the predicted deviations from ideal gas mixing behavior.
		The index of refraction for deuterium for white light is slightly smaller than that of hydrogen: 1.80 x 10/sup -6/.
		ABS>The theory and experimental techniques used for analyzing mixtures of hydrogen-nitrogen and deuterium-nitrogen over the entire range of compositions are given.
	www.osti.gov /energycitations/product.biblio.jsp?osti_id=4283483 (145 words)

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In the News (Mon 28 Dec 09)