Biometry data and accurate intraocular lens iol calculations are very important in achieving the desired refractive outcomes. New mode for measuring axial length with an optical low. In order to use the advantage of a strong reference power p r for measuring eye length, i developed a singlebeam optical lowcoherence reflectometer olcr device using an external reference mirror. Osa polarizationsensitive lowcoherence reflectometer for. A fiber optic based optical low coherence reflectometer has been investigated for process monitoring applications that include its use with both transparent and highly scattering materials. We discuss application of this novel tool for measurements of the narrow high aspect ratio structures. Metaanalysis of optical lowcoherence reflectometry versus partial. Pdf on sep 22, 1999, cyril lupi and others published optical low coherence reflectometry. Optical coherence tomography is a new imaging technique analogous to ultrasound b scan that can provide crosssectional images of the retina with micrometerscale resolution. Us5291267a optical lowcoherence reflectometry using. The new haagstreit lenstar ls 900 measures all of the above parameters and additionally retinal thickness in the optical line utilising optical low coherence reflectometry olcr technology in. Using a singlebackscatter model of a turbid biological. In this paper, we present results of theoretical and experimental investigations of the variables that affect the backscattered signals measured by lowcoherence reflectometers from dense tissues.
The interferometrybased reflectometer supports measurement of specimen reflections with depth separation of a few. 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. We present a polarizationsensitive optical coherence domain reflectometer capable of characterizing the phase retardation between orthogonal linear polarization modes at each reflection point in a birefringent sample. The invention utilizes a reference signal comprising multiple copies of a light signal to increase the range of distance measurements over which the reflectometer operates. The precise and rapid measurement ofeye length and eye shape isessential for investigating eye growth regulation andmyopia. Osa polarizationsensitive lowcoherence reflectometer. The lowcoherence reflectometer with the proposed optical delay line can perform a rapid scanning imaging and two dimensional. 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. Comparison of a new optical biometer using sweptsource optical coherence tomography and a biometer using optical low coherence reflectometry. Highspeed measurements in optical lowcoherence reflectometry. The device is insensitive to the rotation of the sample in the plane perpendicular to ranging. Optical coherence tomography is based on lowcoherence interferometry, typically. Optical delay line for rapid scanning lowcoherence reflectometer.
Polarization sensitive optical low coherence reflectometry for blood glucose monitoring in human subjects. Optical low coherence reflectometry olcr is a whitelight interference technique originally developed for applications in the optoelectronics test and measurement arena 1,2. J cataract refract surg central corneal thickness measurement. New developments find, read and cite all the research you need. The low coherence reflectometer with the proposed optical delay line can perform a rapid scanning imaging and two dimensional. To evaluate optical coherence tomography, a new technique for highresolution crosssectional imaging of the retina, for quantitative assessment of retinal thickness in patients with macular edema. However, the envelopes of the interferograms are usually considered asthe. The aim of this study was to compare measurements using a new optical low coherence reflectometry olcr biometer oa2000 and the gold standard partial coherence interferometry pci optical. Burgess fiber optic lowcoherence reflectometer for process control. Each copy of the light signal is delayed by a different amount. We describe a highspeed optical coherence domain reflectometer. Pdf a new optical low coherence reflectometry device for ocular. Optical lowcoherence reflectometry olcr is a whitelight interference technique originally developed for applications in the optoelectronics test and measurement arena 1,2. To evaluate optical ocular components in patients with pseudoexfoliation syndrome using optical lowcoherence reflectometry.
Abstract objective to determine the practicability and accuracy of central corneal thickness cct measurements in living chicks utilizing a noncontact, high. Multiplex sensing using optical lowcoherence reflectometry. Haagstreit followed with an optical biometry unit with optical lowcoherence reflectometry olcr, the lenstar ls900. 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. Clinical comparison of biometry using the noncontact. The motivation lies in the desire for an environmentally stable technique to precisely measure drift in the earths crust. Olcr abbreviation stands for optical lowcoherence reflectometry. Optical coherence tomographyprinciples and applications. A generalized approach to optical lowcoherence reflectometry. Us5268738a extended distance range optical lowcoherence. An otdr is the optical equivalent of an electronic time domain reflectometer.
Lowcost optical reflection techniques for the assessment. Ascan ultrasound biometers enable measurements of axial length al, anterior chamber depth acd, lens thickness lt and usually also central corneal thickness cct. Regardless of hair color, the refractive index of the cortical region remains within the range of 1. Mirrors m 3 and m 4 are mounted on a manual translation stage, which allows the. Fiber optic lowcoherence reflectometer for process control.
Olcr stands for optical lowcoherence reflectometry. The fiberbased optical lowcoherence reflectometer of claim 1, wherein variation of the variable wave retarder is from zero to one wavelength. Pdf optical characterization of photonic crystal fibers. An improved lowcoherence reflectometer is disclosed for use in measuring rayleigh backscattering. Download fulltext pdf polarizationsensitive low coherence reflectometer for birefringence characterization and ranging article pdf available in journal of the optical society of america b 96.
Optical coherence tomography of the human retina jama. Pdf polarizationsensitive lowcoherence reflectometer for. Pdf polarizationsensitive lowcoherence reflectometer. The preferred optical amplifier is a diodepumped superfluorescent fiber which acts both as the amplifier and the low coherence light source. Optical coherence domain reflectometer insideview ocdr reference. Dual reference arm lowcoherence interferometerbased. The use of reflectometry has since diversified greatly, including the development of the 2d medical imaging technique optical coherence tomography 3. In order to use the advantage of a strong reference power p r for measuring eye length, i developed a singlebeam optical low coherence reflectometer olcr device using an external reference mirror. The introduction of optical lowcoherence reflectometry olcr to perform noncontact optical biometry is one of the most relevant advances in cataract surgery and iol power calculation in the past few years. What is the abbreviation for optical lowcoherence reflectometry. An improved low coherence reflectometer is disclosed for use in measuring rayleigh backscattering. Olcr optical lowcoherence reflectometer otdr optical timedomain reflectometer. Assaf harofe medical center ophthalmology outpatient clinic, zerifin, israel. Comparison of a new optical biometer using sweptsource optical coherence tomography and a.
Apart from the wtw distance, measurements for al, acd and keratometry readings may be used interchangeability with both devices. Aug 01, 2005 the paper reports initial experimentation with an optical low coherence reflectometer with two linked reference arms for optical coherence tomography oct application. S0034488503187039 optical coherence tomographyprinciples and applications a f fercher 1, w drexler, c k hitzenberger and t lasser2 1 institute of medical physics, university of vienna, waehringer strasse, a1090 wien, austria 2 laboratoire. Institute of physics publishing reports on progress in physics rep. Optical coherence domain reflectometer insideview ocdr. We propose novel tool employing both low coherence interferometer and spectrally resolved reflectometer sensor. The optical delay line possesses the benefits that it is compact, easy to fabricate and can avoid walkoff problem during scanning.
Citeseerx document details isaac councill, lee giles, pradeep teregowda. In contrast, optical techniques such as optical coherence tomography oct, partial coherence interferometry pci, laser doppler interferometry ldi, and optical low coherence reflectometry olcr. Reflectometers based on lowcoherence interferometry are potentially useful tools for probing superficial biological structures. The preferred optical amplifier is a diodepumped superfluorescent fiber which acts both as the amplifier and the lowcoherence light source. Combined lowcoherence interferometry and spectrally. Predictive accuracy of partial coherence interferometry. Osa characterization of human scalp hairs by optical low. The aim of this study was to compare measurements using a new optical low coherence reflectometry olcr biometer oa2000 and the gold standard partial. Optical lowcoherence reflectometry olcr is a technique based on interferometry which is design to detect and localize reflectorsl. Optical lowcoherence reflectometry has been used extensively in ranging of optical components1,2 and more. 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. Optical lowcoherence reflectometry how is optical low. 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. For this purpose, we developedan optical low coherence reflectometer olcr andpresent preliminary measurements.
Goldblumcomparison and evaluation of ocular biometry using a new noncontact optical lowcoherence reflectometer. We present a polarizationsensitive optical coherencedomain reflectometer capable of characterizing the phase retardation between orthogonal linear polarization modes at each reflection point in a birefringent sample. The amplitude of the backscattered infrared light coupled into differentcolored hair confirms the relative melanin content. A 3 db fused coupler was used to couple the low coherence signal to the sensor array and the reflected signals to the autocorrelator. As shown in the diagram at left, a wideband optical light source is launched into a beam splitter and divided into two. Signaldependent specklelike noise was the dominant noise in a brillouin grating measurement with micrometerresolution optical low coherence reflectometry.
Olcr abbreviation stands for optical low coherence reflectometry. We demonstrate the use of optical gating techniques for determining the size and location of subsurface defects in advanced ceramic materials. The invention utilizes an optical amplifier to amplify the backscattered light thereby reducing the measurement times. The fiberbased optical lowcoherence reflectometer of claim 8, wherein the analogtodigital converter is a two channel 12bit analogtodigital converter. Olcr optical lowcoherence reflectometry acronymfinder. The new haagstreit lenstar ls 900 measures all of the above parameters and additionally retinal thickness in the optical line utilising optical low coherence reflectometry olcr technology in a noncontact fashion. Optical delay line for rapid scanning lowcoherence. What is the abbreviation for optical low coherence reflectometry. Download fulltext pdf polarizationsensitive lowcoherence reflectometer for birefringence characterization and ranging article pdf available in journal of the optical society of. The high sensitivity was accomplished by using a high. International audienceoptical lowcoherence reflectometry olcr is a technique based on interferometry which is design to detect and localize reflectorsl. Lowcoherence, highresolution optical reflectometry for.
Lowcost optical reflection techniques for the assessment of. By utilizing a buried optical fiber segment spanning the region to be. 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. Signaldependent specklelike noise was the dominant noise in a brillouin grating measurement with micrometerresolution optical low coherence reflectometry olcr. These include partial coherence interferometry pci,7,1011 lowcoherence reflectometry,12 optical coher ence tomography oct,15 and scanningslit topogra phypachymetry. Meter measures the level of reflected optical power z that is inherent to the. Optical low coherence reflectometry is used to investigate the internal structure and optical properties of human scalp hair. A lowcoherence reflectometer realized by combining a fiber michelson interferometer and a lowcoherence length optical source forms the basic building block of a fiber optical coherence tomography oct system. When, as in the diagram, the measured sample consists of a stack of. Twentytwo patients hospitalized at our eye clinic undergoing cataract surgery were assigned to. It is used for medical imaging and industrial nondestructive testing ndt. Optical low coherence reflectometry and the ofdr optical frequency. Survey examination with optical coherence tomography of patients with macular edema.
Optical lowcoherence reflectometry is used in this noncontacting depth scanning method. 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. A commercially available optical lowcoherence reflectometer hp 8504a precision reflectometer performed the autocorrelation function. In vivo measurement of central corneal thickness in normal. 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 backscatter or reflected back from points along the fiber.
Lowcoherence interferometry lci is a noncontact optical sensing technology an optical probe directs a beam of lowcoherence light at a sample surface and sends reflected light signals to an interferometric detector interferometer via an optical fiber for interpretation. Survey optical coherence tomographic examination of the retina, including the macula and optic nerve head in normal human subjects. Axial and peripheral eye length measured with optical low. Clinical comparison of biometry using the noncontact optical. Metaanalysis of optical lowcoherence reflectometry. The noise was produced by the interaction of a stokes signal with beat noise caused by a leaked pump light via squarelaw detection.
Sensors free fulltext signaltonoise ratio of brillouin. Metaanalysis of optical lowcoherence reflectometry versus. The resultant signaltonoise ratio snr was calculated and found to be proportional to the. Cataract surgery is the most common surgical procedure in ophthalmology. Comparison of optical lowcoherence reflectometry and. By utilizing a buried optical fiber segment spanning the region to be measured, one. Download pdf 759 kb abstract international audienceoptical low coherence reflectometry olcr is a technique based on interferometry which is design to detect and localize reflectorsl. An improved optical lowcoherence reflectometer is disclosed for use in measuring the strength and location of optical reflections. Optical low coherence reflectometry olcr is a technique based on interferometry which is design to detect and localize reflectorsl. Predictive value of intracrystalline interphase point. Twentytwo patients hospitalized at our eye clinic undergoing. In 1999, carl zeiss meditec ag introduced an optical biometry unit based on partial coherence interferometry pci, the iolmaster. An optical low coherence reflectometry olcr system has been developed for precise optical fiber length change measurement. Sensitivity advantage of swept source and fourier domain.
A birefringentfiberbased dualchannel optical lowcoherence reflectometer capable of differential phase measurement is described. Measurement of eye length and eye shape by optical low. Sensors free fulltext signaltonoise ratio of brillouin grating. When, as in the diagram, the measured sample consists of a stack of semitransparent material layers, light. Optical characterization of dense tissues using low. An optical timedomain reflectometer otdr is an optoelectronic instrument used to characterize an optical fiber. Quantitative assessment of macular edema with optical. A low coherence light source 14 is used to illuminate device 12. Mar 01, 1994 the manner in which a low coherence reflectometer operates may be more easily understood with reference to fig. Fiberbased optical low coherence tomography dave digant p. The resultant signaltonoise ratio snr was calculated and found to be. An optical lowcoherence reflectometry olcr system has been developed for precise optical fiber length change measurement. Optical lowcoherence reflectometry how is optical lowcoherence reflectometry abbreviated. We demonstrate that the visible reflectance spectrum of such structures allows us to extend range of interferometer to measure depth trenches with.
Optical lowcoherence reflectometry enables preoperative. A lowcoherence light source 14 is used to illuminate device 12. It is now possible to scan samples with high spatial resolution and constant high speed 2. In this paper, we first develop a general theory of optical lowcoherence reflectometry including spectral filtering. The manner in which a lowcoherence reflectometer operates may be more easily understood with reference to fig.
Predictive accuracy of partial coherence interferometry and. The manner in which a low coherence reflectometer operates may be more easily understood with reference to fig. The manner in which an optical low coherence reflectometer utilizing a balanced detector operates may be more easily understood with reference to fig. A birefringentfiberbased dualchannel optical low coherence reflectometer capable of differential phase measurement is described. A metaanalysis to compare ocular biometry measured by optical low coherence reflectometry lenstar ls900. Pdf a new commercially available optical low coherence reflectometry device lenstar, haagstreit or allegro biograph, wavelight. Optical low coherence reflectometry listed as olcr. Gpcocdr insideviewtm is an optical coherence domain reflectometer ocdr designed to obtain spaceresolved reflection information inside a fiber optical component, such as a photonic integrated circuit pic, for diagnosing quality or design issues. Scan speeds of 40 mms are achieved with a dynamic range of 90 db and a spatial resolution of 17 gm. Optical lowcoherence reflectometry for nondestructive. Lowcoherence, highresolution optical reflectometry. Oct 17, 2016 cataract surgery is the most common surgical procedure in ophthalmology. 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. Repeatability was determined from 10 successive measurements in each of 4 healthy patients.
This definition appears somewhat frequently and is found in the following acronym finder categories. A metaanalysis to compare ocular biometry measured by optical lowcoherence reflectometry lenstar ls900. Highresolution reflectometer aq7410b the aq7410b is a highresolution optical lowcoherence reflectometer based upon a michelson interferometer. Low coherence interferometry lci is a noncontact optical sensing technology. Osa optical lowcoherence reflectometer for differential. Optical lowcoherence reflectometer for differential phase. Haag streit and partial coherence interferometry the iolmaster optical biometer.
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