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Adrian Gh. Podoleanu

Bio: Adrian Gh. Podoleanu is an academic researcher from University of Kent. The author has contributed to research in topics: Optical coherence tomography & Interferometry. The author has an hindex of 43, co-authored 517 publications receiving 7754 citations. Previous affiliations of Adrian Gh. Podoleanu include University of Texas Health Science Center at San Antonio & Politehnica University of Bucharest.


Papers
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Journal ArticleDOI
TL;DR: The en-face optical coherence tomography system, equipped with the 3D rendering feature acts as a valuable diagnostic tool allowing "peeling off" of transversal and longitudinal biologic material to investigate different internal features.
Abstract: We demonstrate the functionality of an en-face optical coherence tomography (OCT) system with images from the retina and skin. En-face images collected at different depths are subsequently used to reconstruct a 3D volume of the tissue. The reconstruction allows software inferred OCT longitudinal images at any transversal position in the stack. The position in depth in the stack before creating longitudinal OCT images is also adjustable, offering a valuable guidance tool for exploring the 3D volume of the tissue. This is illustrated by Quick time movies showing either depth or lateral exploration along one of two possible different directions in the stack of transversal OCT images. Sufficient accuracy of the volume rendered is obtained in 20 seconds when the system operates at 2 frames a second. The system, equipped with the 3D rendering feature acts as a valuable diagnostic tool allowing “peeling off” of transversal and longitudinal biologic material to investigate different internal features.

330 citations

Journal ArticleDOI
TL;DR: An optical coherence tomography (OCT) system to produce both longitudinal and transversal images of the in vivo human eye is presented in this article, where a path modulation is introduced by the galvanometric scanning mirror and is used as an effective phase modulation method.
Abstract: An optical coherence tomography (OCT) system to produce both longitudinal and transversal images of the in vivo human eye is presented. For the first time, OCT transversal images collected from the living eye at 50-µm depth steps show details unobtainable with the state-of-the-art scanning laser ophthalmoscope. Images of up to 3×3?mm are produced from the retina in less than a second. For images larger than 1.6×1.6?mm, a path modulation is introduced by the galvanometric scanning mirror and is used as an effective phase modulation method.

274 citations

Journal ArticleDOI
TL;DR: A novel optical path-modulation technique for a low-coherence interferometric imaging system based on transverse scanning of the target with a galvanometric scanning-mirror pair is introduced.
Abstract: We introduce a novel optical path-modulation technique for a low-coherence interferometric imaging system based on transverse scanning of the target with a galvanometric scanning-mirror pair. The path modulation arises when the beam that is incident upon one of the scanning mirrors does not fall on its axis of rotation. The method is demonstrated by the production of en-face low-coherence images of different objects such as a fiber-optic tip and a human retina in vivo.

268 citations

PatentDOI
TL;DR: The review provides a concise explanation of principles of operation of different optical coherence tomography methods and a comparative analysis of their advantages and disadvantages is presented in relation to specific applications.
Abstract: An optical coherence tomography (OCT) apparatus includes an optical source, an interferometer generating an object beam and a reference beam, a transverse scanner 11 for scanning an object with said object beam, and a processor for generating an OCT image from an OCT signal returned by said interferometer. At least the optical source, the interferometer, and the scanner are mounted on a common translation stage 30 displaceable towards and away from said object. The optical components mounted on the stage are configured to maintain a coherence gate C in approximate coincidence with the focus F during the displacement of the transition stage.

221 citations

Patent
25 Nov 1998
TL;DR: In this paper, an optical mapping apparatus with adjustable depth resolution is provided. But it is not adjustable for the curvature at the back of the eye lens, as in this paper.
Abstract: Optical mapping apparatus with adjustable depth resolution is provided. The optical mapping apparatus can display transversal images in an object, particularly the eye. The apparatus can deliver two or more images with different depth resolutions, or a combination of these images, or only one image with adjustable depth resolution. There is also provided optical mapping apparatus with adjustable depth resolution, where OCT images are corrected for the curvature at the back of the eye lens.

216 citations


Cited by
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Journal Article
TL;DR: In this article, a fast Fourier transform method of topography and interferometry is proposed to discriminate between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour generation techniques.
Abstract: A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

3,742 citations

01 Jun 2005

3,154 citations

Journal ArticleDOI
TL;DR: Results are presented which demonstrate the superior sensitivity of swept source (SS) and Fourier domain (FD) optical coherence tomography (OCT) techniques over the conventional time domain (TD) approach.
Abstract: We present theoretical and experimental results which demonstrate the superior sensitivity of swept source (SS) and Fourier domain (FD) optical coherence tomography (OCT) techniques over the conventional time domain (TD) approach. We show that SS- and FD-OCT have equivalent expressions for system signal-to-noise ratio which result in a typical sensitivity advantage of 20-30dB over TD-OCT. Experimental verification is provided using two novel spectral discrimination (SD) OCT systems: a differential fiber-based 800nm FD-OCT system which employs deep-well photodiode arrays, and a differential 1300nm SS-OCT system based on a swept laser with an 87nm tuning range.

2,109 citations

Journal ArticleDOI
TL;DR: It is shown that FDOCT systems have a large sensitivity advantage and allow for sensitivities well above 80dB, even in situations with low light levels and high speed detection.
Abstract: In this article we present a detailed discussion of noise sources in Fourier Domain Optical Coherence Tomography (FDOCT) setups. The performance of FDOCT with charge coupled device (CCD) cameras is compared to current standard time domain OCT systems. We describe how to measure sensitivity in the case of FDOCT and confirm the theoretically obtained values. It is shown that FDOCT systems have a large sensitivity advantage and allow for sensitivities well above 80dB, even in situations with low light levels and high speed detection.

2,104 citations

Journal ArticleDOI
TL;DR: OCT as discussed by the authors synthesises cross-sectional images from a series of laterally adjacent depth-scans, which can be used to assess tissue and cell function and morphology in situ.
Abstract: There have been three basic approaches to optical tomography since the early 1980s: diffraction tomography, diffuse optical tomography and optical coherence tomography (OCT). Optical techniques are of particular importance in the medical field, because these techniques promise to be safe and cheap and, in addition, offer a therapeutic potential. Advances in OCT technology have made it possible to apply OCT in a wide variety of applications but medical applications are still dominating. Specific advantages of OCT are its high depth and transversal resolution, the fact, that its depth resolution is decoupled from transverse resolution, high probing depth in scattering media, contact-free and non-invasive operation, and the possibility to create various function dependent image contrasting methods. This report presents the principles of OCT and the state of important OCT applications. OCT synthesises cross-sectional images from a series of laterally adjacent depth-scans. At present OCT is used in three different fields of optical imaging, in macroscopic imaging of structures which can be seen by the naked eye or using weak magnifications, in microscopic imaging using magnifications up to the classical limit of microscopic resolution and in endoscopic imaging, using low and medium magnification. First, OCT techniques, like the reflectometry technique and the dual beam technique were based on time-domain low coherence interferometry depth-scans. Later, Fourier-domain techniques have been developed and led to new imaging schemes. Recently developed parallel OCT schemes eliminate the need for lateral scanning and, therefore, dramatically increase the imaging rate. These schemes use CCD cameras and CMOS detector arrays as photodetectors. Video-rate three-dimensional OCT pictures have been obtained. Modifying interference microscopy techniques has led to high-resolution optical coherence microscopy that achieved sub-micrometre resolution. This report is concluded with a short presentation of important OCT applications. Ophthalmology is, due to the transparent ocular structures, still the main field of OCT application. The first commercial instrument too has been introduced for ophthalmic diagnostics (Carl Zeiss Meditec AG). Advances in using near-infrared light, however, opened the path for OCT imaging in strongly scattering tissues. Today, optical in vivo biopsy is one of the most challenging fields of OCT application. High resolution, high penetration depth, and its potential for functional imaging attribute to OCT an optical biopsy quality, which can be used to assess tissue and cell function and morphology in situ. OCT can already clarify the relevant architectural tissue morphology. For many diseases, however, including cancer in its early stages, higher resolution is necessary. New broad-bandwidth light sources, like photonic crystal fibres and superfluorescent fibre sources, and new contrasting techniques, give access to new sample properties and unmatched sensitivity and resolution.

1,914 citations