An improved low coherence reflectometer is disclosed for use in measuring rayleigh backscattering. The invention generally relates to an optical coherence tomography system that is reconfigurable between two different imaging modes and methods of use thereof. Comparison of 3 biometry devices in cataract patients. Optical delay line for rapid scanning lowcoherence. Quantitative assessment of macular edema with optical. The articles prior to january 20 are part of the back file collection and are not available with a current paid subscription. However, the envelopes of the interferograms are usually considered asthe.
Comparison of optical lowcoherence reflectometry and. Phasesensitive optical lowcoherence reflectometry for. We demonstrate the use of optical gating techniques for determining the size and location of subsurface defects in advanced ceramic materials. Olcr abbreviation stands for optical low coherence reflectometry. Extendedrangeopticallowcoherence reflectometryusinga. This method utilizes the coherence effects exhibited by a broadband optical source and is referred to as optical coherence domain reflectometry.
Optical low coherence reflectometry olcr is a whitelight interference technique. Lowcost optical reflection techniques for the assessment of. We secondly describe the third interferometer coupled to a white. Osa optical lowcoherence reflectometry for complete. We show that the olcr technique requires only short samples of fiber optical low coherence reflectometry versus partial coherence interferometry biometry. The concept was initially employed in heterodyne scanning microscopy. Twentytwo patients hospitalized at our eye clinic undergoing cataract surgery were assigned to.
It is used for medical imaging and industrial nondestructive testing ndt. A 3 db fused coupler was used to couple the low coherence signal to the sensor array and the reflected signals to the autocorrelator. The scan rate and scan range of the reflectometer are measured to be 2. Green center for process analytical chemistry university of washington box 351700 seattle, wa 981951700 abstract. Optical mixing of the lo cal oscillator lo light and the end. Optical delay line for rapid scanning lowcoherence reflectometer. Optical lowcoherence reflectometry how is optical low. Axial and peripheral eye length measured with optical low. An otdr is the optical equivalent of an electronic time domain reflectometer. A genzeralized approach to optical lowcoherence reflectometry including spectral filtering effects. Lowcoherence interferometry has found a widespread use in optical low coherence reflectometry olcr, employed to measure optical return loss of optical. Optical coherence tomography is a new, noninvasive, noncontact optical imaging modality that has.
The experimental results are in good agreement with the theoretical predictions of the path length variation model. The invention utilizes an optical amplifier to amplify the backscattered light thereby reducing the measurement times. Optical low coherence reflectometry olcr is a technique based on interferometry which is design to detect and localize reflectorsl. The twoelement scanning system is used to generate rapid signal acquisition in an optical low coherence reflectometer. We present the structure of photonic crystal fibers and give a characterization results in birefringence and chromatic dispersion using scanning near field optical microscopy and low coherence interferometry. Comparison of a new optical biometry with an optical lowcoherence. Multiplex sensing using optical lowcoherence reflectometry. It is now possible to scan samples with high spatial resolution and constant high speed 2.
The aim of our study was to report the accuracy of olcr biometry obtained from the lenstar ls900 haagstreit ag, koniz, switzerland in predicting post operative refraction in eyes undergoing phacovitrectomy for macular pathology erm or mh. Optical coherence tomography oct is an imaging technique that uses low coherence light to capture micrometerresolution, two and threedimensional images from within optical scattering media e. Within the framework of the european acts project bliss broadband lightwave sources and systems, a first prototype of an optical frequency domain reflectometer ofdr has been developed. A phasesensitive optical low coherence reflectometry olcr technique is demonstrated to simultaneously measure the absolute chromatic dispersion values of each guided lp mode of a fewmode fiber. Optical lowcoherence reflectometry has been used extensively in ranging of optical components1. Noise in optical lowcoherence reflectometry ieee xplore.
Abstract in the interpretation of optical lowcoherence re flectometry measurements, the reflectivity of the device under test is in general supposed to be with a. By measuring the multiplied fiber length under test, the measurement precision is enhanced. Robust and rapid optical lowcoherence reflectometer using a. Purpose to evaluate the repeatability and reproducibility of the measurements obtained with the argos, a new biometer with sweptsource optical coherence tomography ssoct, and to compare them with the results obtained with the iolmaster 500 partial coherence interferometry pci and the lenstar ls 900 optical low coherence reflectometry olcr biometers. Optical frequency domain reflectometry is a new technique, designed to measure backreflections from optical fiber networks and components 1. Extendedrange optical lowcoherence reflectometry using a.
Repeatability and reproducibility of biometry and keratometry. Oct can produce in real time a crosssection image of the object, i. One of them is filtered through a fibre bragg grating sample under stress and the results. Optical lowcoherence reflectometry olcr is a technique based on. Sensitivity advantage of swept source and fourier domain optical coherence tomography michael a. It injects a series of optical pulses into the fiber under test and extracts, from the same end of the fiber, light that is scattered rayleigh. The optical delay line possesses the benefits that it is compact, easy to fabricate and can avoid walkoff problem during scanning. Optical lowcoherence reflectometry enables preoperative. Optical lowcoherence reflectometer for differential phase. Lowcoherence, highresolution optical reflectometry for. Pdf a new commercially available optical low coherence reflectometry device lenstar, haagstreit or allegro.
Biometry measurements using a new largecoherencelength swe. It is based on an interferometric method that uses a probe light characterized by a broad spectrum. Optical low coherence reflectometry olcr is a technique that permits to measure the absolute position and to determine optical properties. Optical lowcoherence domain reflectometry olcr has proven to be very effective for the measurement of small closelyspaced optical reflections.
In this study, we compared al, acd, and k values of 3 optical biometers in a clinical cohort of patients with agerelated. The low coherence reflectometer with the proposed optical delay line can perform a rapid scanning imaging and two dimensional. Such reflections are often encountered in optical fiberbased communications systems and can cause degraded performance. Low coherence, highresolution optical reflectometry for fiber length measurement by jerome thomas b.
Optical lowcoherence reflectometry for nondestructive. Grating with lengths below two millimeters have been fabricated in standard telecommunication fibers. Background theory is given, and experimental results have demonstrated a resolution of. Scan speeds of 40 mms are achieved with a dynamic range of 90 db and a spatial resolution of 17 gm. Comparability of anterior chamber depth measurements with. We report on low coherence, nearinfrared reflectometry applied to optical fibres, waveguides, and coupling devices to detect the echoes due to reflective propagation defects and measure their. Us5291267a optical lowcoherence reflectometry using. Sep 18, 2010 the aim of the study was to determine whether the innovative noncontact optical lowcoherence reflectometry method utilized by the lenstar ls 900 agrees sufficiently with applanation ultrasound ascan technique in routine biometric measurement and intraocular lens power calculation to replace it. Comparison of agederived lens thickness to optically. We present theoretical and experimental results which. It uses optical lowcoherence reflectometry olcr with a 820 nm laser.
What is the abbreviation for optical low coherence reflectometry. Low coherence interferometry lci is a noncontact optical sensing technology an optical probe directs a beam of low coherence light at a sample surface and sends reflected light signals to an interferometric detector interferometer via an optical fiber for interpretation. Conference proceedings papers presentations journals. Optical coherence tomograms of cystoid macular edema closely corresponded to known histopathologic characteristics. To evaluate optical ocular components in patients with pseudoexfoliation syndrome using optical low coherence reflectometry. Comparison of a new optical biometry with an optical lowcoherence reflectometry for ocular biometry. We describe a highspeed optical coherence domain reflectometer.
Photoncounting optical coherencedomain reflectometry using superconducting singlephoton detectors nishant mohan1, olga minaeva2,3, gregory n. Optical low coherence reflectometry olcr is applied to the precise characterization of bragg gratings in optical fibers. An optical timedomain reflectometer otdr is an optoelectronic instrument used to characterize an optical fiber. Milner optical techniques may potentially be used for noninvasive glucose sensing. Development and applications 411 organizing this data by areas of knowledge and looking only for the most expressive ones, fig. High resolution optical low coherence reflectometry in.
A birefringentfiberbased dualchannel optical low coherence reflectometer capable of differential phase measurement is described. Phase noise owing to environmental perturbations that is common to both channels is canceled, resulting in accurate measurement of the phase difference between light backscattered from two spatially separated sites. Micrometerscale resolution imaging of the anterior eye in. Currently, several instruments are available such as slitscanning topography systems, scheimpflug topography, optical coherence tomography, partial coherence interferometry, and optical low coherence reflectometry. Optical coherence tomographyprinciples and applications. Jan 01, 2012 read repeatability and reproducibility of biometry and keratometry measurements using a noncontact optical low coherence reflectometer and keratometer, american journal of ophthalmology on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. That is because of the vacancy of technologies capable to perform images with. Quantitative measurement of retinal thickness is possible because of the welldefined boundaries in optical reflectivity at the inner and outer margins of the neurosensory retina. To compare refractive outcomes using the lenstar optical lowcoherence reflectometry olcr biometer in the following cases.
Phasesensitive optical lowcoherence reflectometry for the detection of analyte concentrations kirill v. Oct 18, 2011 optical coherence tomography oct is a noninvasive high resolution optical imaging technology based on interference between signal from an object under investigation and a local reference signal. Pdf a new optical low coherence reflectometry device for ocular. Advanced photonics journal of applied remote sensing. Lowcoherence, highresolution optical reflectometry for fiber length measurement by jerome thomas b.
Doppler interferometry ldi, and optical low coherence reflectometry. In the 1990s, ultrasound derivation of al and manual keratometry. Optical low coherence domain reflectometry olcr has proven to be very effective for the measurement ofsmall closelyspaced optical reflections. Low coherence interferometry is an attractive technique for sensor measurementsav, while it maintains the accuracy of conventional single frequency i. To demonstrate a new diagnostic technique, optical coherence tomography, for highresolution crosssectional imaging of structures in the anterior segment of the human eye in vivo.
Small volumes located at the inside of the sample can be studied individually and with a high sensitivity. An optical evaluation technique is described that is suitable for determining the positions and magnitudes of reflection sites within miniature optical assemblies. Sensitivity advantage of swept source and fourier domain. Metaanalysis of optical lowcoherence reflectometry versus partial. A generalized approach to optical lowcoherence reflectometry. Sep 05, 2017 this book is a systematic treatment of one of these fieldsthe broad area that deals with the coherence and fluctuation of light. Optical lowcoherence reflectometry of efficient bragg. Comparability of anterior chamber depth measurements with partial coherence interferometry and optical low coherence reflectometry in pseudophakic eyes presented at the 18th winter meeting of the european society of cataract and refractive surgeons, ljubljana, slovenia, february 2014. In contrast, optical techniques such as optical coherence tomography oct. Highresolution measurement of fiber length change with. Pdf optical characterization of photonic crystal fibers. Methods a prospective cohort study of 224 eyes of patients planned for cataract surgery was conducted in the period from january 2009 until july 2009.
We report on lowcoherence, nearinfrared reflectometry applied to optical fibres, waveguides, and coupling devices to detect the echoes due to reflective propagation defects and measure their. To demonstrate a novel swept source optical coherence tomography ssoct imaging device employing a vertical cavity surfaceemitting laser vcsel capable of imaging the full eye length and to introduce a method employing this device for noncontact optical ocular biometry. In vivo pachymetry in normal eyes of rats, mice and. Reproducibility of a longrange swept source optical. Optical coherence tomography system that is reconfigurable. The preferred optical amplifier is a diodepumped superfluorescent fiber which acts both as the amplifier and the low coherence light source. Optical lowcoherence interferometry for selected technical. Optical low coherence reflectometry for nondestructive process measurements summer lockerbie randall, anatol m. Osa optical lowcoherence reflectometer for differential.
A commercially available optical lowcoherence reflectometer hp 8504a precision reflectometer performed the autocorrelation function. A fiberring structure composed of a coupler and a circulator is introduced in the test arm of olcr to virtually multiply the length of the fiber under test. Adding lateral scanning to a low coherence interferometer, allows depth resolved acquisition of 3d information from the volume of biologic material. Photoncounting optical coherencedomain reflectometry using. Pdf a genzeralized approach to optical lowcoherence.
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