Insights into sweptwavelength characterization of passive fiberoptic components. Advances in sweptwavelength interferometry for precision measurements written by eric d. The frequencysampling method is widely used to accommodate nonlinear electromagnetic source tuning in sweptwavelength interferometric techniques, such as optical frequency domain. A schematic illustration of a sweptwavelength interferometer for performing range. Wavelengthtuning interferometry of intraocular distances. Multiple wavelength interferometry mwi is a technique were the use of at least two different wavelengths allows the generation of a synthetic wavelength much longer than the two individual optical wavelengths, actually increasing the nonambiguity range nar for interferometry dandliker et al. Highaccuracy length metrology using multiple stage swept. Pdf on may 1, 2012, alexandre cabral and others published dimensional. Optical setup for two wavelength superheterodyne interferometry. Wavelength references for interferometry in air richard w. Absolute distance metrology using frequency swept lasers oxford.
This invention relates generally to a system and method for detecting flashback events in a combustor of a gas turbine. The high signaltonoise ratios typical of sweptwavelength interferometry swi enable distance measurements to be superresolved with theoretical 2. We describe the use of swept wavelength interferometry for distributed fiberoptic strain and temperature sensing in single mode and gradient index multimode fiber. A method, system and apparatus for obtaining a parameter of interest from a plurality of sensors in a fiber optic cable deployed in a wellbore are disclosed. The broadsweepers series is a new family of tunable semiconductor lasers intended for applications that require fast and precision wavelength tuning with high sweeptosweep reproducibility of the. One beam is reflected from the reference mirror, and the other one from the sample. Mcleod, superresolved sweptwavelength interferometry using frequency estimation methods, opt. A key component of an ssoct system is the light source. Sweptwavelength interferometric interrogation of fiber. Optical coherence tomography oct is an imaging technique that uses lowcoherence light to capture micrometerresolution, two and threedimensional images from within optical scattering media e. Dynamic absolute distance measurement by frequency sweeping interferometry based doppler beat frequency tracking model. One beam is reflected from the reference mirror, and the other one. Coherent absolute distance interferometry is one of the most interesting techniques for length metrology.
Mcleod originally developed for radar applications in the 1950s, swept wavelength interferometry swi at optical wavelengths has been an active area of research. The imaging lens images the interferogram onto the ccd camera. Vibration tolerant swept wavelength interferometry. These two beams are recombined by the beamsplitter to interfere. Typical interferometer the expanded beam exiting from the light source is divided by a beamsplitter into two beams. An approach for compensating the influence of the interrogator noises on the readings of interferometric sensors, interrogated by means of spectral interferometry with wavelength tuning is proposed.
Building a sweptwavelength system requires a tunable laser source, the device under test, power sensors, and a dataacquisition system. Sweptwavelength interferometric interrogation of fiber rayleigh scatter for distributed sensing applications. Enhancing the resolution limits of spectral interferometric measurements with sweptwavelength interrogation by means of a reference interferometer nikolai ushakov,1, alexandr markvart,1 leonid liokumovich1 1 department of radiophysics, st. The method is used to measure strain in a fourstrand multimode cable under twist. Swept frequency acoustic interferometry remediation weekly. The oa2000 is a biometer based on fourier domain technology by light interference using a sweptsource laser with a wavelength of 1,060 nm. Advances in sweptwavelength interferometry for precision. The sweptwavelength method for highresolution wavelength. Advances in swept wavelength interferometry for precision measurements thesis directed by associate professor robert r. Ssoct detects wavelengthresolved interference frin ges generated by a wavelength scanning laser. Superresolved sweptwavelength interferometry using frequency estimation methods.
Interferometry is a family of techniques in which waves, usually electromagnetic waves, are superimposed, causing the phenomenon of interference, which is used to extract information. Us8592747b2 programmable filters for improving data. Osa characterization of coupledcore fiber amplifiers. As motivated in the last paragraph, this occurs when the angular. Osa superresolved sweptwavelength interferometry using. Moore has been approved for the department of electrical, computer, and energy engineering robert r. In this paper, a sweptwavelength interferometry swi based dofs technique is used to monitor the fatigue in a.
At a given optical wavelength, an interference signal varies as a sinusoidal function of distance with a period equal to the wavelength. Absolute distance measurement using frequency sweeping. The spectral phase response of a reference gas cell in the vicinity of. A 780 nm diode laser sweptfrequency heterodyne facility is described and its use demonstrated for accurate determination of the optical path length of two stable fabryperot etalons. Estimated pdf of envelope amplitude sn at the passband central frequency fn 0 for different. Kulhavy we describe basic principles of wavelengthtuning interferometry and demonstrate its.
Dimensional metrology and frequency sweeping interferometry. The length result from one synthetic wavelength is typically used to determine the fringe order of the next shorter synthetic wavelength. In this work, we combine the sweptwavelength interferometry swi with a. The high signaltonoise ratios typical of sweptwavelength interferometry swi enable distance measurements to be superresolved with 2. Swept wavelength interferometry allows measurement of the polarization resolved complex transfer function h. Fatigue damage monitoring of a composite step lap joint. Characterization of coupledcore fiber amplifiers using swept. Dynamic absolute distance measurement by frequency. Wyant this paper describes a method to enhance the capability of twowavelength phaseshifting interferometry. Characterization of coupledcore fiber amplifiers using swept wavelength interferometer juan carlos alvaradozacarias, charles mattebreton, roland ryf, nicolas k. We present a characterization technique for coupled spacedivision multiplexed sdm amplifiers, that can measure the complex transfer matrix over the whole wavelength range of interest of an amplifier.
Sweptwavelength interferometry allows the rayleigh scatter amplitude and phase to be sampled with very high spatial resolution 10s of microns. Influence of nonlinearities in wavelengthswept absolute distance interferometry perret, luc 20070618 00. It is possible to change this amplitude by varying either the wavelength sweptfrequency interferometry, sihna 12 or the distance sweptdistance interferometry, mcclements 911. Direct phase measurement interferometry and optical testing phasestepping and phaseshifting basic concept phase shifters algorithms phaseunwrapping phase shifter calibration errors. The rayleigh scatter complex amplitude can be fourier. Interferometry introduction interferometers are devices employed in the study of interference patterns produced by various light sources. Influence of nonlinearities in wavelengthswept absolute. Superresolved sweptwavelength interferometry using. Direct phase measurement interferometry and optical testing.
Enhancing the resolution limits of spectral interferometric measurements with sweptwavelength interrogation by means of a reference interferometer nikolai ushakov,1, alexandr markvart,1. Fontaine, haoshuo chen, steffen wittek, hirotaka sakuma, takafumi ohtsuka, tetsuya hayashi, takemi hasegawa, sophie larochelle, and rodrigo amezcuacorrea. Highspeed optical coherence tomography system using a. Sweptwavelength interferometry for sdm amplifier characterization.
Comprehensive comparison of axial length measurement with. Argos uses a 1,060 nm wavelength sweptsource technology and records a twodimensional oct image from the corneal apex to the macula. Wavelengthtuning interferometry of intraocular distances f. Swept wavelength laser s3 key features custom oem con. Multiple wavelength interferometry mwi is a technique were the use of at least. Request pdf vibration tolerant swept wavelength interferometry we describe a vibration tolerant coherent interferometer. Sweptwavelength interferometric interrogation of fiber rayleigh. Sweptwavelength interferometric analysis of multiport. Osa high resolution distributed strain or temperature. Multiwavelength interferometry for length measurements using. Newbury, and leo hollberg cavitymode wavelengths in air are determined by measuring a lasers frequency. Although this approach offers unrivaled precision, the periodic signal. Multiplewavelength phaseshifting interferometry yeouyen cheng and james c.
Petersburg state polytechnical university, polytechnicheskaya, 29, 195251, st. In frequency sweeping interferometry fsi, measurements are made without ambiguity, by using a. Optical interferometry in astronomy 793 is resolved by an interferometer if the fringe contrast goes to zero at the longest baseline. Originally developed for radar applications in the 1950s, sweptwavelength interferometry swi at optical wavelengths has been an active area.
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