Showing papers on "Optical coherence tomography published in 1993"
TL;DR: These images represent the highest depth resolution in vivo retinal images to date and are to the authors' knowledge the first in vivo measurements of human retinal structure with optical coherence tomography.
Abstract: We describe what are to our knowledge the first in vivo measurements of human retinal structure with optical coherence tomography. These images represent the highest depth resolution in vivo retinal images to date. The tomographic system, image-processing techniques, and examples of high-resolution tomographs and their clinical relevance are discussed.
1,049 citations
573 citations
TL;DR: A new technique, femtosecond transillumination optical coherence tomography, for time-gated imaging of objects embedded in scattering media, derives a fundamental limit on ballistic imaging thickness based on quantum noise considerations.
Abstract: We describe a new technique, femtosecond transillumination optical coherence tomography, for time-gated imaging of objects embedded in scattering media. Time gating is performed with a fiber-optic interferometer with femtosecond pulses and coherent heterodyne detection to achieve a 130-dB dynamic range. A confocal imaging arrangement provides additional spatial discrimination against multiply scattered light. By time gating ballistic photons, we achieve 125-microm-resolution images of absorbing objects in media 27 scattering mean free paths thick. We derive a fundamental limit on ballistic imaging thickness based on quantum noise considerations.
286 citations
TL;DR: In this paper, diffuse-light time-gated imaging with transillumination optical coherence tomography was proposed to obtain submillimeter-resolution imaging of objects hidden in biological tissue.
Abstract: We describe diffuse-light time-gated imaging with transillumination optical coherence tomography. Submillimeter-resolution imaging of objects hidden in thick biological tissue is achieved in cases in which ballistic light is absent by selecting only the early-arriving coherent portion of the diffuse transmitted light. By using a femtosecond laser as a high-power low-coherence light source, we perform high-sensitivity (130-dB dynamic range) optical gating with interferometric heterodyne detection. The dependence of image resolution on coherent photon arrival time is investigated in model scattering media.
126 citations
Patent•
17 Dec 1993TL;DR: In this paper, a beam scanner was used to illuminate the fundus of an eye with a scanned sample beam of radiation, which was used for optical coherence tomography. But the beam scanner is fixed with respect to the scan fundus so that the point of final deflection is located substantially in the back focal plane of the scanner lens.
Abstract: Apparatus for illuminating the fundus of an eye with a scanned sample beam of radiation, the scanned sample beam emerging from a beam scanner which is exposed to a sample beam, which apparatus is for use in optical coherence tomography. An embodiment of the apparatus includes: (a) scanner lens and a beamsplitter for transferring radiation from the scanned sample beam, including chief rays of the sample beam which emerge from a point of final deflection of the beam scanner, and (b) a lens for focusing the transferred radiation so that the scanned sample beam is focused onto the fundus by the eye. In accordance with the invention the scanner lens is fixed with respect to the beam scanner so that the point of final deflection is located substantially in the back focal plane of the scanner lens and the scanner lens is movable.
101 citations
49 citations
TL;DR: A new technique for coherent optical imaging of ocular structure based on optical coherence tomography (OCT), a noncontact, noninvasive, tomographic imaging technique with superior spatial resolution to ultrasound and high sensitivity, is presented.
Abstract: We present a new technique for coherent optical imaging of ocular structure based on optical coherence tomography (OCT). OCT is a noncontact, noninvasive, tomographic imaging technique with superior spatial resolution to ultrasound (< 20 micrometers ) and high sensitivity (100 dB dynamic range). We have used OCT to perform direct imaging of ocular structure in the anterior and posterior segments of human eyes in vitro and in vivo. In the anterior segment, we have measured corneal thickness and profile, anterior chamber depth and angle, and iris thickness and profile. These and other possible measurements have potential applications in diagnosis of pathologies of the cornea, angle, and iris, as well as in noncontact biometry for applications in cataract and corneal refractive surgeries. In the posterior segment, we have obtained high-resolution images of retinal structure in human subjects in vivo. These images demonstrate higher resolution than available with any other existing technique, and include characterization of optic disk morphology and topology. These measurements have potential applications in early diagnosis and assessment of glaucoma and other retinal diseases.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
46 citations
05 Aug 1993
TL;DR: In this article, the dual beam interferometry technique was proposed to compensate for the movements of the subject during the measurement of optical coherence tomography images of the human eye.
Abstract: If the more or less conventional interferometric techniques are applied in vivo, movements of the subject might falsify the measurement. This led us to develop the dual beam interferometry technique which compensates for these movements. First in vivo tomographic images of the human eye are presented. The implications of the application of partial coherence techniques in dispersive media are discussed. Synthesizing tomograms from interfero- metrically obtained scans is rather time-consuming and therefore difficult to apply in vivo. Hence we discuss the application of spectral interferometry to optical coherence tomography. The spectral interferometry technique does not need moving components.
22 citations
15 Aug 1993
TL;DR: Techniques for non-invasive biomedical imaging include nuclear magnetic resonance, ultrasound, positron emission tomography, x-ray computed to- mography, and optical transillumination.
Abstract: Techniques for non-invasive biomedical imaging include nuclear magnetic resonance, ultrasound, positron emission tomography, x-ray computed to- mography, and optical transillumination. Each of these methods has dif- ferent advantages and limitations and has found particular applications in medicine. Optical imaging of tissue offers the potential of a non-invasive diagnostic with non-ionizing radiation and the possibility of using spectro- scopic properties to distinguish tissue type and probe metabolic function.
14 citations
Proceedings Article•
02 May 1993TL;DR: In this article, the first in vivo transpupillary measurements of the human retina were reported. But they were performed in a single image and not in a set of images of the entire human retina.
Abstract: Optical coherence tomography (OCT) has recently been developed as a new technique for high resolution measurements of biological tissue.1,2 OCT is an extension of low coherence interferometry techniques for optical ranging measurement,3,4 which permits the measurement of false color, cross-sectional images. OCT is particularly attractive in ophthalmic applications where it can non-invasively provide quantitative measurements of a variety of ocular diseases. We have previously demonstrated imaging of tire anterior chamber of a human eye in vitro, in cold-induced cataracts of a calf eye in vitro, in the retinal structure of a bisected human eye in vitro, and in the retinal structure of a rabbit eye in vivo. In this paper we report, as we know it, the first in vivo, transpupillary measurements of the human retina.
TL;DR: In this article, a femtosecond transillumination optical coherence tomography (FTEOCOMT) was proposed to achieve time-gated and spatially resolved imaging through diffusive biological tissue by selecting either the earliest arriving unscattered ballistic component or the least scattered portion of the diffuse transmitted light.
Abstract: We describe a new technique called femtosecond transillumination optical coherence tomography which combines femtosecond pulses, coherent heterodyne detection, and fiber- optic confocal imaging to achieve time-gated and spatially resolved imaging through diffusive biological tissue. Images of absorbing objects embedded in scattering biological media are demonstrated by selecting either the earliest arriving unscattered ballistic component or the least scattered portion of the diffuse transmitted light. Time and spatially resolved analysis of photon migration through model scattering systems is used to establish fundamental limits for this class of time-gated and spatially resolved optical imaging techniques, and to evaluate their potential biomedical applications in early tumor diagnosis.