Articles from opticsinfobase.org

1. Motion artifact suppression in full-field optical coherence tomography

   Explore Article opticsinfobase.org (Mar 8 2010)

   Significant motion artifacts limit the performance of conventional full-field optical coherence tomography (FF-OCT) for in-vivo imaging. We present a theoretical and experimental study of those limitations. A new FF-OCT system suppressing most of artifacts due to sample motions is demonstrated using instantaneous phase shifting with nonpolarizing optics and pulsed illumination. The experimental setup is based on a Linnik-type interferometer illuminated by the superluminescence emission from a Ti:Al2O3 waveguide crystal. En face tomographic images are calculated as a combination of two phase-opposed interferometric images acquired simultaneously by two CCD cameras placed at both outputs of the interferometer, with a spatial resolution ... (Read Full Article)
   

   Comment on Article Mentions:   Arnaud Dubois   Institut d'Optique

2. Ce^3+:YAG double-clad crystal-fiber-based optical coherence tomography on fish cornea

   Explore Article opticsinfobase.org (Mar 4 2010) Broadband Sources

   A Ce3+:YAG double-clad crystal fiber (DCF) visible emission was used as the light source for optical coherence tomography (OCT). The visible emission was produced from a 10 μm core DCF pumped by a diode laser. The broadband emission and short central wavelength of this light source enabled the realization of 1.5 μm axial resolution in air. The relatively clean spectrum reduced the side lobe of its point-spread function, and therefore facilitated the generation of a high-quality image with less crosstalk between adjacent image pixels. As a demonstration, an Aplocheilus lineatus goldfish was experimented on to map out the stroma of ... (Read Full Article)
   

   Comment on Article Mentions:   National Taiwan University

3. Fast dispersion encoded full range optical coherence tomography for retinal imaging at 800 nm and 1060 nm

   Explore Article opticsinfobase.org (Feb 24 2010) Ophthalmology

   The dispersion mismatch between sample and reference arm in frequency-domain optical coherence tomography (OCT) can be used to iteratively suppress complex conjugate artifacts and thereby increase the imaging range. In this paper, we propose a fast dispersion encoded full range (DEFR) algorithm that detects multiple signal components per iteration. The influence of different dispersion levels on the reconstruction quality is analyzed experimentally using a multilayered scattering phantom and in vivo retinal tomograms at 800 nm. Best results have been achieved with 30 mm SF11, with neglectable resolution decrease due to finite resolution of the spectrometer. Our fast DEFR algorithm achieves ... (Read Full Article)
   

   Comment on Article Mentions:   Wolfgang Drexler   Boris Hermann   Boris Povazay

4. Photothermal optical coherence tomography in ex vivo human breast tissues using gold nanoshells

   Explore Article opticsinfobase.org (Feb 23 2010)

   We demonstrate photothermal optical coherence tomography (OCT) imaging in highly scattering human breast tissue ex vivo. A 120 kHz axial scan rate, swept-source phase-sensitive OCT system at 1300 nm was used to detect phase changes induced by 830 nm photothermal excitation of gold nanoshells. Localized phase modulation was observed 300-600 μm deep in scattering tissue using an excitation power of only 22 mW at modulation frequencies up to 20 kHz. This technique enables integrated structural and molecular-targeted imaging for cancer markers using nanoshells. (Read Full Article)
   

   Comment on Article Mentions:   James G. Fujimoto   Desmond C. Adler   Massachusetts Institute of Technology

5. In situ 24 kHz coherent imaging of morphology change in laser percussion drilling

   Explore Article opticsinfobase.org (Feb 18 2010) Other Non-Medical

   We observe sample morphology changes in real time
   24 kHz during and between percussion drilling pulses by integrating a low-coherence microscope into a laser micromachining platform. Nonuniform cut speed and sidewall evolution in stainless steel are observed to strongly depend on assist gas. Interpulse morphology relaxation such as hole refill is directly imaged, showing dramatic differences in the material removal process dependent on pulse duration/peak power (
   s/0.1 kW, ps/20 MW) and material (steel, lead zirconate titanate PZT). Blind hole depth precision is improved by over 1 order of magnitude using in situ feedback from the imaging system. (Read Full Article)
   

   Comment on Article Mentions:   James M. Fraser   Victor X. D. Yang   University of Toronto

6. High speed optical coherence microscopy with autofocus adjustment and a miniaturized endoscopic imaging probe

   Explore Article opticsinfobase.org (Feb 17 2010) Endoscopy , Microscopy , Probes

   ical coherence microscopy (OCM) is a promising technique for high resolution cellular imaging in human tissues. An OCM system for high-speed en face cellular resolution imaging was developed at 1060 nm wavelength at frame rates up to 5 Hz with resolutions of < 4 µm axial and < 2 µm transverse. The system utilized a novel polarization compensation method to combat wavelength dependent source polarization and achieve broadband electro-optic phase modulation compatible with ultrahigh axial resolution. In addition, the system incorporated an auto-focusing feature that enables precise, near real-time alignment of the confocal and coherence gates in tissue, allowing user-friendly ... (Read Full Article)
   

   Comment on Article Mentions:   James G. Fujimoto   Shu-Wei Huang   Aaron D. Aguirre

7. Photoacoustic ophthalmoscopy for in vivo retinal imaging

   Explore Article opticsinfobase.org (Feb 12 2010) Ophthalmology

   We have developed a non-invasive photoacoustic ophthalmoscopy (PAOM) for in vivo retinal imaging. PAOM detects the photoacoustic signal induced by pulsed laser light shined onto the retina. By using a stationary ultrasonic transducer in contact with the eyelids and scanning only the laser light across the retina, PAOM provides volumetric imaging of the retinal micro-vasculature and retinal pigment epithelium at a high speed. For B-scan frames containing 256 A-lines, the current PAOM has a frame rate of 93 Hz, which is comparable with state-of-the-art commercial spectral-domain optical coherence tomography (SD-OCT). By integrating PAOM with SD-OCT, we further achieved OCT-guided PAOM, ... (Read Full Article)
   

   Comment on Article Mentions:   Shuliang Jiao   Carmen A. Puliafito   University of Wisconsin

8. Multiple and dependent scattering effects in Doppler optical coherence tomography

   Explore Article opticsinfobase.org (Feb 11 2010) Doppler

   Doppler optical coherence tomography (OCT) is a technique to image tissue morphology and to measure flow in turbid media. In its most basic form, it is based on single (Mie) scattering. However, for highly scattering and dense media multiple and concentration dependent scattering can occur. For Intralipid solutions with varying scattering strength, the effect of multiple and dependent scattering on the OCT signal attenuation and Doppler flow is investigated. We observe a non-linear increase in the OCT signal attenuation rate and an increasingly more distorted Doppler OCT flow profile with increasing Intralipid concentration. The Doppler OCT attenuation and flow measurements ... (Read Full Article)
   

   Comment on Article Mentions:   Academic Medical Center at the University of Amsterdam   Dirk J. Faber   University of Oulu

9. Signal processing for sidelobe suppression in optical coherence tomography images

   Explore Article opticsinfobase.org (Feb 10 2010)

   In an optical coherence tomography system, the sidelobes of the point-spread function (PSF) introduced from the optical source reduce the A-scan imaging resolution and contrast of the images. A gradual iterative signal subtraction method based on the study of a point signal influenced by other points with different distances through the PSF is proposed in this paper. Comparing with the CLEAN algorithm and two typical deconvolution methods, the processed results demonstrate this algorithm can reduce sidelobes effectively with the least runtime. It is also found that it is insensitive to noise while slightly improving the longitudinal resolution, which shows this ... (Read Full Article)
   

   Comment on Article Mentions:   Yanmei Liang   Kuanhong Xu   Nankai University

10. Improvement in dynamic range limitation of swept source optical coherence tomography by true logarithmic amplification

    Explore Article opticsinfobase.org (Feb 10 2010) Tunable Sources

    We previously demonstrated, with both theoretical and experimental studies, the dynamic range limitation with spectral domain optical coherence tomography (OCT) relative to time domain OCT. A significant portion of this limitation was due to the difference of analog/digital conversion. In this paper, a new method of true logarithmic amplification is discussed theoretically and tested experimentally to increase the dynamic range of a swept source OCT. With the current experimental setup, an increase of the dynamic range by about 6 dB was obtained. (Read Full Article)
    

    Comment on Article Mentions:   Mark E. Brezinski   Brigham and Women’s Hospital   Harvard University

11. Gabor-based fusion technique for Optical Coherence Microscopy

    Explore Article opticsinfobase.org (Feb 4 2010) Dermatology , Developmental Biology , Microscopy

    We recently reported on an Optical Coherence Microscopy technique, whose innovation intrinsically builds on a recently reported - 2 μm invariant lateral resolution by design throughout a 2 mm cubic full-field of view - liquid-lens-based dynamic focusing optical probe [Murali et al.,Optics Letters 34, 145-147, 2009]. We shall report in this paper on the image acquisition enabled by this optical probe when combined with an automatic data fusion method developed and described here to produce an in-focus high resolution image throughout the imaging depth of the sample. An African frog tadpole (Xenopus laevis) was imaged with the novel probe and ... (Read Full Article)
    

    Comment on Article Mentions:   University of Rochester   University of Central Florida   Jannick P. Rolland

12. Depth-resolved wavefront aberrations using a coherence-gated Shack-Hartmann wavefront sensor

    Explore Article opticsinfobase.org (Feb 3 2010)

    In the present paper we investigate the possibility of narrowing the depth range of a physical Shack – Hartmann (SH) wavefront sensor (WFS) by using coherence gating. For the coherence gating, two low coherence interferometry (LCI) methods are evaluated and proof of principle configurations demonstrated: (i) a time domain LCI method based on phase shifting interferometry and (ii) a spectral domain LCI method, based on tuning a narrow band optical source. The two configurations are used to demonstrate each, the possibility of constructing a coherence gated (CG) SH/WFS. It is shown that these configurations produce spot patterns similar to those ... (Read Full Article)
    

    Comment on Article Mentions:   Adrian G. Podoleanu   University of Kent

13. Swept-source polarization-sensitive
optical coherence tomography based on
polarization-maintaining fiber

    Explore Article opticsinfobase.org (Feb 2 2010)

    We present a swept-source polarization-sensitive optical coherence tomography system based on a polarization-maintaining fiber interferometer. The system produces reflectivity and birefringence information along a depth profile with a single sweep of the optical spectrum. Unlike single-mode fiber systems, retardance and relative optical axis orientation images are calculated without compensation. The source is a 45 mW polygon-based swept-source centered at 1290 nm and tuned at a rate of 28 kHz. The interferometer consists of a single polarization-maintaining coupler that utilizes balanced detection for improved performance. Characterization data shows that this system yields accurate measurements with high sensitivity (106.2 dB) comparable to ... (Read Full Article)
    

    Comment on Article Mentions:   Taner Akkin   University of Minnesota

14. Simultaneous measurement of group refractive index and thickness of optical samples using optical coherence tomography

    Explore Article opticsinfobase.org (Feb 1 2010)

    ical coherence tomography (OCT), based on a Michelson interferometer and utilizing low coherence light as the optical source, is a novel technique for the noninvasive imaging of optical scattering media. A simple OCT scheme based on a 3×3 fiber coupler is presented for the simultaneous measurement of the refractive index and thickness of optical samples. The proposed system enables the refractive index and thickness to be determined without any prior knowledge of the sample parameters and is characterized by a simple and compact configuration, a straightforward measurement procedure, and a low cost. The feasibility of the proposed approach is demonstrated ... (Read Full Article)
    

    Comment on Article

15. In vitro characterization of cardiac radiofrequency ablation lesions using optical coherence tomography

    Explore Article opticsinfobase.org (Jan 28 2010) Cardiology

    Currently, cardiac radiofrequency ablation (RFA) is guided by indirect signals. We demonstrate optical coherence tomography (OCT) characterization of RFA lesions within swine ventricular wedges. Untreated tissue exhibited a consistent birefringence artifact within OCT images due to the organized myocardium, which was not present in treated tissue. Birefringence artifacts were detected by filtering with a Laplacian of Gaussian (LoG) to quantify gradient strength. The gradient strength distinguished RFA lesions from untreated sites (p=5.93x10-15) with a sensitivity and specificity of 94.5% and 86.7% respectively. This study demonstrates the potential of OCT for monitoring cardiac RFA, confirming lesion formation and providing feedback to ... (Read Full Article)
    

    Comment on Article Mentions:   Hui Wang   Christine P. Fleming   Andrew M. Rollins

16. Diffusive and directional intracellular dynamics measured by field-based dynamic light scattering

    Explore Article opticsinfobase.org (Jan 27 2010)

    Quantitative measurement of diffusive and directional processes of intracellular structures is not only critical in understanding cell mechanics and functions, but also has many applications, such as investigation of cellular responses to therapeutic agents. We introduce a label-free optical technique that allows non-perturbative characterization of localized intracellular dynamics. The method combines a field-based dynamic light scattering analysis with a confocal interferometric microscope to provide a statistical measure of the diffusive and directional motion of scattering structures inside a microscopic probe volume. To demonstrate the potential of this technique, we examined the localized intracellular dynamics in human epithelial ovarian cancer cells. ... (Read Full Article)
    

    Comment on Article Mentions:   Chulmin Joo   Johannes F. de Boer   Massachusetts General Hospital

17. Optical distortion correction in Optical Coherence Tomography for quantitative ocular anterior segment by three-dimensional imaging

    Explore Article opticsinfobase.org (Jan 26 2010) Ophthalmology

    A method for three-dimensional 3-D optical distortion (refraction) correction on anterior segment Optical Coherence Tomography (OCT) images has been developed. The method consists of 3-D ray tracing through the different surfaces, following denoising, segmentation of the surfaces, Delaunay representation of the surfaces, and application of fan distortion correction. The correction has been applied theoretically to realistic computer eye models, and experimentally to OCT images of: an artificial eye with a Polymethyl Methacrylate (PMMA) cornea and an intraocular lens (IOL), an enucleated porcine eye, and a human eye in vivo obtained from two OCT laboratory set-ups (time domain and spectral). Data ... (Read Full Article)
    

    Comment on Article Mentions:   Maciej Wojtkowski   Ireneusz Grulkowski   Nicolaus Copernicus University

18. Measuring morphological features using light-scattering spectroscopy and Fourier-domain low-coherence interferometry

    Explore Article opticsinfobase.org (Jan 25 2010)

    e present measurements of morphological features in a thick turbid sample using light-scattering spectroscopy (LSS) and Fourier-domain low-coherence interferometry (fLCI) by processing with the dual-window (DW) method. A parallel frequency domain optical coherence tomography (OCT) system with a white-light source is used to image a two-layer phantom containing polystyrene beads of diameters 4.00 and 6.98
    m on the top and bottom layers, respectively. The DW method decomposes each OCT A-scan into a time–frequency distribution with simultaneously high spectral and spatial resolution. The spectral information from localized regions in the sample is used to determine scatterer structure. The results show that ... (Read Full Article)
    

    Comment on Article Mentions:   Francisco E. Robles   Adam Wax   Duke University

19. Quantitative cerebral blood flow with Optical Coherence Tomography

    Explore Article opticsinfobase.org (Jan 22 2010) Doppler

    Vivek J. Srinivasan, Sava Sakadžić, Iwona Gorczynska, Svetlana Ruvinskaya, Weicheng Wu, James G. Fujimoto, David A. BoasAbsolute measurements of cerebral blood flow (CBF) are an important endpoint in studies of cerebral pathophysiology. Currently no accepted method exists for in vivo longitudinal monitoring of CBF with high resolution in rats and mice. Using three-dimensional Doppler Optical Coherence Tomography and ... [Opt. Express 18, 2477-2494 (2010)] (Read Full Article)
    

    Comment on Article Mentions:   James G. Fujimoto   Vivek J. Srinivasan   Iwona Gorczyńska

20. OSA to Launch New Open-Access Journal in Fall 2010

    Explore Article opticsinfobase.org (Jan 21 2010)

    The Optical Society (OSA) is launching a new peer-reviewed journal focusing on biomedical optics and photonics. Biomedical Optics Express will debut this fall, joining OSA's portfolio of 10 peer-reviewed optics journals. •Online-only peer-reviewed journal following the rapid-publishing open-access model of Optics Express •Interactive science publishing (ISP) capability for online visualization of large datasets •Automated submission of published articles to PubMed Central to assist authors funded by the U.S. National Institutes of Health •Journal launch Fall 2010; submissions accepted beginning April 2010 Biomedical Optics Express will become OSA's principal outlet for serving the biomedical optics community with rapid, open-access publication of ... (Read Full Article)
    

    Comment on Article Mentions:   Duke University   Joseph A. Izatt

21. Polarization-maintaining fiber based polarization-sensitive optical coherence tomography in spectral domain

    Explore Article opticsinfobase.org (Jan 19 2010)

    We demonstrate a polarization-sensitive spectral-domain optical coherence tomography system based on polarization-maintaining fiber technology. Using a single-line-scan camera, the system produces reflectivity and retardance information along a depth profile with a single measurement. The relative axis orientation is available as well. System design and characterization and images of a biological tissue are presented. (Read Full Article)
    

    Comment on Article Mentions:   University of Minnesota   Taner Akkin   Hui Wang

22. Wavelength-swept spectral and pulse shaping utilizing hybrid Fourier domain modelocking by fiber optical parametric and erbium-doped fiber amplifiers

    Explore Article opticsinfobase.org (Jan 15 2010) Tunable Sources

    We report the first Fourier domain modelocked (FDML) laser constructed using optical parametric amplifier (OPA) in conjunction with an erbium-doped fiber amplifier (EDFA), centered at ~1555nm, to the best of our knowledge. We utilize a one-pump OPA and a C-band EDFA in serial configuration with a tunable Fabry-Perot interferometer to generate a hybrid FDML spectrum. Results demonstrate a substantially better spectral shape, output power and stability than individual configurations, with decreased sensitivity to polarization changes. We believe this technique has the potential to enable several amplifiers to complement individual deficiencies resulting in improved spectral shapes and power generation for imaging ... (Read Full Article)
    

    Comment on Article Mentions:   University of Toronto   Victor X. D. Yang   Beau A. Standish

23. Single-camera polarization-sensitive spectral-domain OCT by spatial frequency encoding

    Explore Article opticsinfobase.org (Jan 14 2010)

    We present a polarization-sensitive spectral-domain optical-coherence-tomography system that is capable of retrieving, with a single camera, both retardation and optical axis orientation. The method is based on a differentiation between orthogonal polarization channels through spatial modulation introduced by an electro-optic modulator. Proof-of-principle measurements using a wave plate as a sample are provided, and results of the method for in vivo imaging of the birefringent structures within the human nail fold are presented. Furthermore, we demonstrate the capability of such systems to perform ultra-high-speed polarization-sensitive imaging at 100.000 A-scans/s. (Read Full Article)
    

    Comment on Article Mentions:   Michael Pircher   Erich Gotzinger   Rainer A. Leitgeb

24. Adaptive optics retinal scanner for one-micrometer light source

    Explore Article opticsinfobase.org (Jan 12 2010) Ophthalmology

    We developed an adaptive optics (AO) retinal scanner by using a light source with a center wavelength of 1-um. In a recent study on optical coherence tomography (OCT), it was proved that 1-um light provided higher image contrast of deep region of the eye than 840-nm light. Further, high lateral resolution retinal images were obtained with AO. In this study, we performed measurements on two normal subjects in the AO-SLO mode and analyzed its performance toward developing the AO-OCT. With AO correction, we found that the residual RMS wavefront error of ocular aberration was less than 0.1 μm. We also ... (Read Full Article)
    

    Comment on Article Mentions:   Shuichi Makita   Yoshiaki Yasuno   University of Tsukuba

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