1. Articles from Adrian G. Podoleanu

    25-48 of 58 « 1 2 3 »
    1. 20 mW, 70 nm bandwidth ASE fibre optic source at 1060 nm wavelength region for optical coherence tomography

      20 mW, 70 nm bandwidth ASE fibre optic source at 1060 nm wavelength region for optical coherence tomography
      Optical coherence tomography (OCT) imaging at 1060 nm region proved to be a successful alternative in ophthalmology not only for resolving intraretinal layers, but also for enabling sufficient penetration to monitor the sub-retinal vasculature in the choroids when compared to most commonly used OCT imaging systems at 800 nm region. To encourage further clinical research at this particular wavelength, we have developed a compact fiber optic source based on amplified spontaneous emission (ASE) centered at ~1060 nm with ~70 nm spectral bandwidth at full-width half maximum (FWHM) and output power >20 mW. Our approach is based on a combination of ...
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    2. Camera Adapter Based Optical Imaging Apparatus (Wo 2009/098516)

      Camera Adapter Based Optical Imaging Apparatus (Wo 2009/098516)
      The invention describes several embodiments of an adapter which can make use of the devices in any commercially available digital cameras to accomplish different functions, such as a fundus camera, as a microscope or as an en-face optical coherence tomography (OCT) to produce constant depth OCT images or as a Fourier domain (channelled spectrum) optical coherence tomography to produce a reflectivity profile in the depth of an object or cross section OCT images, or depth resolved volumes,. The invention admits addition of confocal detection and provides simultaneous measurements or imaging in at least two channels, confocal and OCT, where the ...
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    3. Active axial eye motion tracking by extended range closed loop OPD-locked white light interferometer for combined confocal/en face optical coherence tomography imaging of the human eye fundus in vivo

      We report an active tracking device based on white light coherence ranging using a spectrally interrogated Michelson interferometer, which is used to monitor and correct for the axial displacement of the eye and head of the subject in a confocal scanning ophthalmoscope/ en face OCT system (SLO/OCT). ... [Proc. SPIE 7372, 73721R (2009)] published Thu Jul 16, 2009.
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    4. Marginal adaptation of ceramic veneers investigated with en face optical coherence tomography

      The aim of this study was to analyze the quality of marginal adaptation and gap width of Empress veneers using en-face optical coherence tomography. The results prove the necessity of investigating the marginal adaptation after each veneer bonding process
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    5. Optical coherence tomography combined with confocal microscopy for investigation of interfaces in class V cavities

      Standardized class V cavities, prepared in human extracted teeth, were filled with Premise (Kerr) composite. The specimens were thermo cycled. The interfaces were examined using a system employing two simultaneous imaging channels, an en-face Optical Coherence Tomography channel and a confocal microscopy channel.
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    6. Occlusal overload investigations by noninvasive technology: fluorescence microscopy and en-face optical coherence tomography

      The aim of this study is the early detection and monitoring of occlusal overload in bruxing patients. En-Face Optical coherence tomography (eF-OCT) and fluorescence microscopy (FM) were used for the imaging of several anterior teeth extracted from patients with light active bruxism. We found a characteristic pattern of enamel cracks, that reached the tooth surface. We concluded that the combination of the en-Face OCT and FM is a promising non-invasive alternative technique for reliable monitoring of occlusal overload.
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    7. Dual optical coherence tomography/fluorescence microscopy for monitoring of Drosophila melanogaster larval heart

      This article demonstrates a combined instrument of two imaging modalities to acquire information on cardiac function in larval Drosophila melanogaster: optical coherence tomography (OCT) and laser scanning fluorescence microscopy (LSFM). For this purpose, a dedicated imaging instrument able to sequentially provide cross-sectional OCT and C-scan LSFM images has been developed. With this dual-imaging system, the heart can be easily located and visualized within the specimen and the change of the heart shape in a cardiac cycle can be monitored. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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    8. Simplified dynamic focus method for time domain OCT

      A new optical arrangement for performing dynamic focus in time domain optical coherence tomography (OCT) is demonstrated. Unlike previously reported schemes which require mechanical coupling of the object and reference arms, this method is confined to the object arm only and therefore does not impose design constraints on the OCT system layout. The scheme is tested on a high lateral resolution OCT system (NA = 0.13) and it is shown that the effective depth of focus is extended from 200 mm to better than 2 mm. The optimum correction is for media with a mean refractive index of 1.4.
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    9. En face optical coherence tomography investigation of apical microleakage after laser-assisted endodontic treatment

      The aim of our study was to evaluate the potential of en face optical coherence tomography (OCT) for the detection of apical microleakage after 980 nm and 1,064 nm laser-assisted endodontic treatment. Ninety, human, single-rooted teeth with one straight root canal and closed apices were used. All roots were prepared biomechanically to the working length at an apical size 30 and 0.06 taper. The teeth were divided into three equal groups of 30 samples each, according to the treatment to be applied to the root canal. Group I received 980 nm diode laser (3 W, 0.01 s ...
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    10. Optical coherence tomography and confocal microscopy investigations of dental structures and restoration materials

      Nowadays, optical tomographic techniques are of particular importance in the medical imaging field, because these techniques can provide non-invasive diagnostic images. The present study evaluates the potential of en-face optical coherence tomography (OCT) as a possible non-invasive high resolution imaging method in supplying the necessary information on the quality of dental hard tissues and defects of dental restorative materials. Teeth after several treatment methods are imaged in order to asses the material defects and micro-leakage of tooth-filling interface as well as to evaluate the quality of dental hard tissue. C-scan and B-scan OCT images as well as confocal images are ...
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    11. Evaluation of effective noise bandwidth for broadband optical coherence tomography operation

      Key noise parameters in optical coherence tomography (OCT) systems employing splitters with a nonflat spectral response are evaluated using a supercontinuum fiber laser source with a spectrum of 450 nm-1700 nm and a time domain OCT architecture based on 1300 nm fiber splitters. The spectral behavior of the splitter leading to balanced detection is measured over a range of 300 nm. Because of spectrally different signals at the balanced detector input a residual excess photon noise term results. A rigorous treatment of this noise term [Appl. Opt.43, 4802 (2004)] introduced two new quantities that take into account the spectral ...

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    12. Multidimensional en-Face OCT imaging of the retina

      Multidimensional en-Face OCT imaging of the retina
      Fast T-scanning (transverse scanning, en-face) was used to build B-scan or C-scan optical coherence tomography (OCT) images of the retina. Several unique signature patterns of en-face (coronal) are reviewed in conjunction with associated confocal images of the fundus and B-scan OCT images. ... [Opt. Express 17, 4112-4133 (2009)]
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    13. From Talbot bands to no mirror terms in Fourier domain OCT: a quest on the fundamental origin of the sensitivity decay with depth

      We show that the decay of sensitivity with depth in Fourier Domain (FD)-OCT can be explained based on the superposition of wavetrain lengths after dispersion (diffraction). The more coherent the dispersed waves are, the slower the decay of sensitivity. An asymmetry in the decay curve with the optical path difference (OPD) can be introduced via an "intrinsic" delay which has the effect of shifting axially the two wavetrains relative to each other, originating from the object and reference beam of an interferometer. In this way, an equivalent Talbot Bands set-up is implemented, characterized by no mirror terms for the ...
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    14. Sequential en-face optical coherence tomography imaging and monitoring of Drosophila Melanogaster larval heart

      This article demonstrates two modalities to acquire information on cardiac function in larval Drosophila Melanogaster: in-vivo imaging and heartbeat monitoring. To achieve these goals a dedicated imaging instrument able to provide simultaneous en-face Optical Coherence Tomography (OCT) and Laser Sca ... [Proc. SPIE 7168, 71680G (2009)] published Thu Feb 19, 2009.
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    15. Early detection of tooth wear by en-face optical coherence tomography

      Excessive dental wear (pathological attrition and/or abfractions) is a frequent complication in bruxing patients. The parafunction causes heavy occlusal loads. The aim of this study is the early detection and monitoring of occlusal overload in bruxing patients. En-face optical coherence tomography w ... [Proc. SPIE 7162, 716205 (2009)] published Wed Feb 18, 2009.
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    16. En-face OCT system at 1060 nm

      En-face OCT system at 1060 nm
      A highly efficient power optical coherence tomography configuration is implemented using a Multiwave Photonics broadband source centred at 1060 nm wavelength, FWHM = 50 nm and a Mach Zehnder interferometer. The interferometer contains a fibre acousto-optic modulator in each arm. One is driven at a fixed frequency of 40 MHz while the other via an RF Function Generation. In this way, the en-face OCT signal is modulated on a carrier frequency adjustable in the range 0 kHz to 1.5 MHz. A circulator is placed in the sample arm. Light retroreflected from the sample is sent via the circulator to a ...
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    17. Multi-channel time domain spectroscopic optical coherence tomography system

      A detection method based on 7 spectral windows at the photodetection stage in an optical coherence tomography system was tested. We investigated its utility in two directions: spectroscopic optical coherence tomography and signal to noise ratio improvement. A diffraction grating was used in the photodetection unit to diffract light over a 16 photodetector array. Currently, this array has been configured to deliver 7 channels only by binning two adjacent photodetectors. The improvement of the signal to noise ratio has been investigated. Preliminary results of spectroscopy analysis which will be shown are B-scan OCT imaging of paint layers. The ultimate aim ...

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    18. A swept source OCT at 1300 nm with angular compounding for art and archaeological conservation

      We have assembled a swept source optical coherence tomography (OCT) system for use in Art & Archaeological Conservation. The system is illuminated by an in-house swept source with a central wavelength of 1300 nm. This system includes dedicated optics to allow for angular averaging for speckle noise ... [Proc. SPIE 7139, 713917 (2008)] published Tue Dec 30, 2008.
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    19. Optical Coherence Tomography in archaeological and conservation science - a new emerging field

      There has been a long tradition of applying biomedical imaging techniques to the examination of historical artefacts, owing to similar demands for non-invasive methods in both fields. Optical Coherence Tomography (OCT) is no exception. We review the achievements on OCT applications to art conservati ... [Proc. SPIE 7139, 713915 (2008)] published Tue Dec 30, 2008.
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    20. Adaptive optics loop for en-face optical coherence tomography and laser scanning confocal microscopy

      The capabilities of a novel deformable mirror and wave-front sensor combination to correct aberrations in microscopy are analyzed. The deformable mirror, (Mirao52-D, Imagine Eyes) is incorporated with a Shack-Hartmann sensor (HASO, Imagine Optic) within a complex imaging system able to produce simultaneous en-face Optical Coherence Tomography and Laser Scanning Confocal Microscopy images as well as B-scan OCT images. A large angle imaging along one of the scanning directions is demonstrated using the AO loop to correct for the interface optics aberration. The image is split into three panels, and each panel is imaged using its own set of corrections. The ...

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    21. Direct corneal elevation measurements using multiple delay en face optical coherence tomography

      Lucian Plesea and Adrian Gh. Podoleanu Optical coherence tomography (OCT) is a well-established imaging method in the ophthalmic practice. We describe a novel corneal topography method that directly measures anterior cornea surface elevation from a single en face OCT image. This method uses an OCT interferometer configuration equipped wi ... [J. Biomed. Opt. 13, 054054 (2008)] published Thu Oct 16, 2008.
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    22. Controlling the shape of Talbot bands visibility

      Controlling the shape of Talbot bands visibility
      We present a theoretical model to predict the sensitivity variation versus optical path difference (OPD) in Fourier domain spectral interferometry using configurations which produce Talbot bands. Such configurations require that the two interfering beams use different parts of the diffraction grating in the interrogating spectrometer. So far, the power distribution within the two beams in a Talbot bands experiment was considered uniform. In this report, we show that by manipulating the power distribution within the two interfering beams, the OPD value where maximum sensitivity is achieved can be conveniently tuned, as well as the sensitivity variation with OPD. Furthermore, creating ...
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    23. Combinations of techniques in imaging the retina with high resolution

      Developments in optical coherence tomography (OCT) have expanded its clinical applications for high-resolution imaging of the retina, as a standalone diagnostic and in combination with other optical imaging modalities. This review presents currently explored combinations of OCT technology with a variety of complementary imaging modalities along with augmentational technologies such as adaptive optics (AO) and tracking. Some emphasis is on the combination of OCT technology with scanning laser ophthalmoscopy (SLO) as well as on using OCT to produce an SLO-like image. Different OCT modalities such as time domain and spectral domain are discussed in terms of their performance and suitability ...
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    24. 1st Workshop on OCT & Adaptive Optics

      1st Workshop on OCT & Adaptive Optics
      The last five years have shown unprecedented developments in the field of tisssue imaging using low power infra-red and visible waves. This workshop will put emphasis on two aspects of non-invasive optical imaging, optical coherence tomography (OCT) and adaptive optics (AO). The workshop will consist of papers presented in mini-symposia and tutorials.
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    25-48 of 58 « 1 2 3 »
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    1. (55 articles) University of Kent
    2. (20 articles) Victor Babes University of Medicine and Pharmacy
    3. (5 articles) New York Eye and Ear Infirmary
    4. (5 articles) Optos
    5. (2 articles) University Fernando Pessoa
    6. (2 articles) State University of New York at Buffalo
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