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Weng W, Kaszubowska-Anandarajah A, Anandarajah PM, Luiten AN. Microresonator-based spectral translation of a gain-switched semiconductor laser comb. OPTICS LETTERS 2023; 48:2309-2312. [PMID: 37126261 DOI: 10.1364/ol.487458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Gain-switched semiconductor laser technology provides a simple and low-cost method to generate optical frequency combs. However, the spectral coverage of these compact comb sources has been limited to the near-infrared range. Here, we combine a gain-switched laser comb with a continuous-wave translation laser within a periodically poled lithium niobate microresonator and demonstrate efficient and broadband sum-frequency conversion, spectrally translating the near-infrared comb to the visible domain. The broadband nature of the nonlinear conversion arises from a chirping of the domain inversion grating period along the microresonator circumference. We also validate the coherence of the visible-wavelength comb teeth which underlines the general applicability of this spectral translation approach.
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2
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Cense B, Maddipatla R, Cervantes Lozano FJ, Joo C. Two concepts for ultra-high-resolution polarization-sensitive optical coherence tomography with a single camera. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2022; 39:1295-1308. [PMID: 36215616 DOI: 10.1364/josaa.458631] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 06/12/2022] [Indexed: 06/16/2023]
Abstract
Two designs with a multiplexed superluminescent diode for ultra-high-resolution spectral-domain polarization-sensitive optical coherence tomography (UHR-PS-OCT) are introduced. In the first design, a Wollaston prism separates orthogonal polarization states next to each other on one linescan camera; the other design uses a beam displacer to separate orthogonal states onto two lines of a linescan camera with multiple rows of detectors. The coherence lengths measured with the two systems were 3.6 µm and 2.9 µm (n=1.38), respectively. Measurements were collected from the fovea of a healthy subject, a healthy subject with astigmatism, and a patient with central serous retinopathy (CSR). A single volumetric scan provides double pass retardance induced by the retinal nerve fiber layer birefringence (RNFL) and its birefringence, the cumulative double pass retardance induced by the Henle fiber layer, and the retardance that is induced by the retinal pigment epithelium-Bruch's membrane complex. The high axial resolution in UHR-PS-OCT is particularly helpful for the measurements of thin retinal tissue, such as the RNFL in the fovea, where birefringence values of around 1°/µm were found. Tilting of the retina due to a CSR or by off centering the imaging beam in the pupil causes an artificial increase in the double pass retardance induced by the RNFL and Henle fiber layer.
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3
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Noise reduction by adaptive-SIN filtering for retinal OCT images. Sci Rep 2021; 11:19498. [PMID: 34593894 PMCID: PMC8484270 DOI: 10.1038/s41598-021-98832-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 09/13/2021] [Indexed: 11/17/2022] Open
Abstract
Optical coherence tomography (OCT) images is widely used in ophthalmic examination, but their qualities are often affected by noises. Shearlet transform has shown its effectiveness in removing image noises because of its edge-preserving property and directional sensitivity. In the paper, we propose an adaptive denoising algorithm for OCT images. The OCT noise is closer to the Poisson distribution than the Gaussian distribution, and shearlet transform assumes additive white Gaussian noise. We hence propose a square-root transform to redistribute the OCT noise. Different manufacturers and differences between imaging objects may influence the observed noise characteristics, which make predefined thresholding scheme ineffective. We propose an adaptive 3D shearlet image filter with noise-redistribution (adaptive-SIN) scheme for OCT images. The proposed adaptive-SIN is evaluated on three benchmark datasets using quantitative evaluation metrics and subjective visual inspection. Compared with other algorithms, the proposed algorithm better removes noise in OCT images and better preserves image details, significantly outperforming in terms of both quantitative evaluation and visual inspection. The proposed algorithm effectively transforms the Poisson noise to Gaussian noise so that the subsequent shearlet transform could optimally remove the noise. The proposed adaptive thresholding scheme optimally adapts to various noise conditions and hence better remove the noise. The comparison experimental results on three benchmark datasets against 8 compared algorithms demonstrate the effectiveness of the proposed approach in removing OCT noise.
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Xue Y, Niu Y, Gong S. External Modulation Optical Coherent Domain Reflectometry with Long Measurement Range. SENSORS 2021; 21:s21165510. [PMID: 34450952 PMCID: PMC8401056 DOI: 10.3390/s21165510] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/14/2021] [Accepted: 07/30/2021] [Indexed: 11/16/2022]
Abstract
Optical coherent domain reflectometry (OCDR) can achieve a high spatial resolution that is independent of the bandwidth of the receiver, but the measurement range is usually very limited. Here we propose an external modulation OCDR system, in which a pair of linear frequency-modulated pulses generated by one modulator are employed as the probe pulse and the reference, respectively. The spatial resolution is determined by the frequency modulation range of the pulse, and the measurement speed is boosted by orders because the proposed technology can simultaneously diagnose a section of fiber with each pair of pulses, while only a single point can be accessed at a time in typical OCDR. In the demonstrational experiment, a measurement range of up to 50 km is achieved with a spatial resolution of 1.4 m and a measuring time of less than 30 s.
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Kufcsák A, Bagnaninchi P, Erdogan AT, Henderson RK, Krstajić N. Time-resolved spectral-domain optical coherence tomography with CMOS SPAD sensors. OPTICS EXPRESS 2021; 29:18720-18733. [PMID: 34154122 DOI: 10.1364/oe.422648] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 05/14/2021] [Indexed: 06/13/2023]
Abstract
We present a first spectral-domain optical coherence tomography (SD-OCT) system deploying a complementary metal-oxide-semiconductor (CMOS) single-photon avalanche diode (SPAD) based, time-resolved line sensor. The sensor with 1024 pixels achieves a sensitivity of 87 dB at an A-scan rate of 1 kHz using a supercontinuum laser source with a repetition rate of 20 MHz, 38 nm bandwidth, and 2 mW power at 850 nm centre wavelength. In the time-resolved mode of the sensor, the system combines low-coherence interferometry (LCI) and massively parallel time-resolved single-photon counting to control the detection of interference spectra on the single-photon level based on the time-of-arrival of photons. For proof of concept demonstration of the combined detection scheme we show the acquisition of time-resolved interference spectra and the reconstruction of OCT images from selected time bins. Then, we exemplify the temporal discrimination feature with 50 ps time resolution and 249 ps timing uncertainty by removing unwanted reflections from along the optical path at a 30 mm distance from the sample. The current limitations of the proposed technique in terms of sensor parameters are analysed and potential improvements are identified for advanced photonic applications.
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Oosterveer TTM, van der Meer SM, Scherptong RWC, Jukema JW. Optical Coherence Tomography: Current Applications for the Assessment of Coronary Artery Disease and Guidance of Percutaneous Coronary Interventions. Cardiol Ther 2020; 9:307-321. [PMID: 32564339 PMCID: PMC7584694 DOI: 10.1007/s40119-020-00185-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Indexed: 01/07/2023] Open
Abstract
INTRODUCTION Coronary angiography (CAG) is the standard modality for assessment of coronary stenoses and intraprocedural guidance of percutaneous coronary interventions (PCI). However, the limitations of CAG are well recognized. Intracoronary imaging (ICI) can potentially overcome these limitations. Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) are the main ICI techniques utilized in clinical practice. AIM This narrative literature review addresses the current clinical applications of OCT in relation to IVUS and CAG in patients with coronary artery disease (CAD). Items reviewed are: technical implications of OCT and IVUS, lesion characterization and decision-making, stent optimization criteria, post-stenting results, safety in terms of procedural complications, clinical outcomes, and indications. MAIN FINDINGS OCT is able to reveal more detail than IVUS due to its higher resolution. However, this higher resolution comes at the cost of a lower penetration depth. Pre-stenting OCT results in procedural change in more than 50% of the cases in terms of stent length and diameter. Post-stenting OCT resulting in stent optimization is reported in at least 27% of the cases. Malapposition and under-expansion are treated with post-dilatations, while edge dissections are treated with additional stent placement. Stent expansion, stent apposition, distal stent edge dissections, and reference lumen areas seem to be the most important stent optimization criteria for both decision-making and for reducing the risk of adverse events during follow-up. Both OCT and IVUS are superior in terms of post-stenting results compared with CAG alone. However, there is no consensus about whether OCT guidance results in better stent expansion than IVUS guidance. OCT, IVUS, and CAG are safe procedures with few reported procedural complications. In general, OCT guidance seems to contribute to favorable clinical outcomes compared with CAG guidance only. However, OCT guidance results in similar clinical outcomes as with IVUS guidance. OCT could be considered for lumen assessment and stent-related morphology in more complex cases in which CAG interpretation remains uncertain. Since OCT and IVUS have distinct characteristics, these techniques are complementary and should be considered carefully for each patient case based on the benefits and limitations of both techniques.
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Affiliation(s)
- Timo T M Oosterveer
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | | | | | - J Wouter Jukema
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
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Bennett A, Davidovitch E, Beiderman Y, Agadarov S, Beiderman Y, Moshkovitz A, Polat U, Zalevsky Z. Corneal thickness measurement by secondary speckle tracking and image processing using machine-learning algorithms. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-10. [PMID: 31797646 PMCID: PMC7005539 DOI: 10.1117/1.jbo.24.12.126001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 11/04/2019] [Indexed: 06/10/2023]
Abstract
Corneal thickness (CoT) is an important tool in the evaluation process for several disorders and in the assessment of intraocular pressure. We present a method enabling high-precision measurement of CoT based on secondary speckle tracking and processing of the information by machine-learning (ML) algorithms. The proposed configuration includes capturing by fast camera the laser beam speckle patterns backscattered from the corneal-scleral border, followed by ML processing of the image. The technique was tested on a series of phantoms having different thicknesses as well as in clinical trials on human eyes. The results show high accuracy in determination of eye CoT, and implementation is speedy in comparison with other known measurement methods.
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Affiliation(s)
- Aviya Bennett
- Bar-Ilan University, Faculty of Engineering, Nanotechnology Center, Ramat-Gan, Israel
| | - Elnatan Davidovitch
- Bar-Ilan University, Faculty of Engineering, Nanotechnology Center, Ramat-Gan, Israel
| | - Yafim Beiderman
- Bar-Ilan University, Faculty of Engineering, Nanotechnology Center, Ramat-Gan, Israel
| | - Sergey Agadarov
- Bar-Ilan University, Faculty of Engineering, Nanotechnology Center, Ramat-Gan, Israel
| | - Yevgeny Beiderman
- Bar-Ilan University, Faculty of Engineering, Nanotechnology Center, Ramat-Gan, Israel
| | - Avital Moshkovitz
- Bar-Ilan University, School of Optometry and Vision Science, Ramat-Gan, Israel
| | - Uri Polat
- Bar-Ilan University, School of Optometry and Vision Science, Ramat-Gan, Israel
| | - Zeev Zalevsky
- Bar-Ilan University, Faculty of Engineering, Nanotechnology Center, Ramat-Gan, Israel
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8
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Yun YH, Joo KN. Novel combined measurement system to characterize film structures by spectral interferometry and ellipsometry. OPTICS EXPRESS 2018; 26:34396-34411. [PMID: 30650862 DOI: 10.1364/oe.26.034396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 12/10/2018] [Indexed: 06/09/2023]
Abstract
We propose a novel measurement system to simultaneously measure surface and thickness profiles of thin film structures, which cannot be realized in typical measurement techniques. This measurement is accomplished by combining spectral interferometry and ellipsometry. These two distinct measurement techniques are involved in a single system by the abnormal optical configuration. Further, the measurement results are complementary in order to characterize film structures. Film thickness profiles are measured by spectroscopic imaging ellipsometry and surface profiles are obtained from the spectral phase by spectrally resolved interferometry. This method eliminates the theoretical spectral phase by film thicknesses. The proposed system can determine the dimensional film structures at once, even though they have multi-layered films, substrate textures, and even thin film layers. In the experiments, each measurement principle was fundamentally verified with standard specimens. Further, a 4-layered film specimen was measured in order to reconstruct its 3D film structure. As the result, the repeatability of spectroscopic imaging ellipsometry was less than 1 nm and that of spectrally resolved interferometry was a few nanometers, which dominantly affected the performance of the whole system. Several issues for improving accuracy and precision of the proposed system are also discussed in this paper.
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Mitsui T, Aoki K. Dynamically enhanced low-coherence interferometry. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:094302. [PMID: 30278758 DOI: 10.1063/1.5025859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 09/05/2018] [Indexed: 06/08/2023]
Abstract
In the investigations of inhomogeneous media, availability of methods to study the interior of the material without affecting it is valuable. Optical coherence tomography provides such a functionality by providing depth resolved images of semi-transparent objects non-invasively. This is especially useful in medicine and is used not only in research but also in clinical practice. Optical coherence tomography characterizes each cross section by its reflectance. The basic physics principle underlying optical coherence tomography is low-coherence interferometry, which is combined with lateral scanning to produce cross sections. It is clearly desirable to obtain more detailed information regarding each cross section, if available. We have developed a system which measures the fluctuation spectra at all depths in low-coherence interferometry. By providing more information for each cross section, this can in principle be effective in tissue characterization and pathological diagnosis. The system uses the time dependence of the low-coherence interferometry data to obtain the fluctuation spectrum at each depth. Additionally, noise reduction is applied to obtain the spectra without unwanted noise, such as shot-noise, which can swamp the signal. The measurement system is applied to samples with no external stimuli, and depth resolved thermal fluctuation spectra of the samples are obtained. These spectra are compared with their corresponding theoretical expectations and are found to agree. The measurement system requires dualizing the detectors in the low-coherence interferometer but otherwise requires little additional equipment. The measurements were performed in ten to a hundred seconds.
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Affiliation(s)
- Takahisa Mitsui
- Research and Education Center for Natural Sciences and Department of Physics, Hiyoshi, Keio University, Yokohama 223-8521, Japan
| | - Kenichiro Aoki
- Research and Education Center for Natural Sciences and Department of Physics, Hiyoshi, Keio University, Yokohama 223-8521, Japan
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10
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Kolokoltsev Y, Gómez-Arista I, Garduño-Mejía J, Avendaño-Alejo M, Treviño-Palacios CG, Kolokoltsev O. Rapid scanning optical delay line based on a diffraction grating pair for a low-coherence reflectometer. APPLIED OPTICS 2018; 57:4542-4550. [PMID: 29877367 DOI: 10.1364/ao.57.004542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 05/02/2018] [Indexed: 06/08/2023]
Abstract
We present a simple low-coherence time-domain interferometric reflectometer with a rapidly scanning optical delay line (RSODL) based on a non-parallel diffraction grating (DG) pair. The novelty of the solution is that the lightwave in the reference channel is focused on a galvo-mirror in a sub-mm static spot, which allows implementation of fast microelectromechanical systems scan optics. It is shown that the DG pair can be operated as a non-dispersive element that provides dynamic group delay of a reference lightwave. The DG pair system is also capable of tuning the RSODL dispersion from negative to positive values. The experimental depth range in air was obtained as large as 2.5 mm for axial resolution of 20 μm.
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Tsai TH, Leggett CL, Trindade AJ, Sethi A, Swager AF, Joshi V, Bergman JJ, Mashimo H, Nishioka NS, Namati E. Optical coherence tomography in gastroenterology: a review and future outlook. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:1-17. [PMID: 29260538 DOI: 10.1117/1.jbo.22.12.121716] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 12/05/2017] [Indexed: 05/18/2023]
Abstract
Optical coherence tomography (OCT) is an imaging technique optically analogous to ultrasound that can generate depth-resolved images with micrometer-scale resolution. Advances in fiber optics and miniaturized actuation technologies allow OCT imaging of the human body and further expand OCT utilization in applications including but not limited to cardiology and gastroenterology. This review article provides an overview of current OCT development and its clinical utility in the gastrointestinal tract, including disease detection/differentiation and endoscopic therapy guidance, as well as a discussion of its future applications.
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Affiliation(s)
- Tsung-Han Tsai
- NinePoint Medical, Inc., Bedford, Massachusetts, United States
| | - Cadman L Leggett
- Mayo Clinics, Division of Gastroenterology and Hepatology, Rochester, Minnesota, United States
| | - Arvind J Trindade
- North Shore University Hospital and Hofstra Northwell School of Medicine, Division of Gastroenterolo, United States
| | - Amrita Sethi
- Columbia University Medical Center, Department of Gastroenterology, New York City, New York, United States
| | - Anne-Fré Swager
- Spaarne Gasthuis and Free University Medical Center, Amsterdam, The Netherlands
| | - Virendra Joshi
- Ochsner Clinic Foundation, Department of Gastroenterology, New Orleans, Louisiana, United States
| | - Jacques J Bergman
- Academic Medical Center, Department of Gastroenterology and Hepatology, Amsterdam, The Netherlands
| | - Hiroshi Mashimo
- Veterans Affairs Boston Healthcare System and Harvard Medical School, Department of Gastroenterology, United States
| | - Norman S Nishioka
- Massachusetts General Hospital, Gastrointestinal Unit, Boston, Massachusetts, United States
| | - Eman Namati
- NinePoint Medical, Inc., Bedford, Massachusetts, United States
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12
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de Boer JF, Leitgeb R, Wojtkowski M. Twenty-five years of optical coherence tomography: the paradigm shift in sensitivity and speed provided by Fourier domain OCT [Invited]. BIOMEDICAL OPTICS EXPRESS 2017; 8:3248-3280. [PMID: 28717565 PMCID: PMC5508826 DOI: 10.1364/boe.8.003248] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 04/26/2017] [Accepted: 05/22/2017] [Indexed: 05/19/2023]
Abstract
Optical coherence tomography (OCT) has become one of the most successful optical technologies implemented in medicine and clinical practice mostly due to the possibility of non-invasive and non-contact imaging by detecting back-scattered light. OCT has gone through a tremendous development over the past 25 years. From its initial inception in 1991 [Science254, 1178 (1991)] it has become an indispensable medical imaging technology in ophthalmology. Also in fields like cardiology and gastro-enterology the technology is envisioned to become a standard of care. A key contributor to the success of OCT has been the sensitivity and speed advantage offered by Fourier domain OCT. In this review paper the development of FD-OCT will be revisited, providing a single comprehensive framework to derive the sensitivity advantage of both SD- and SS-OCT. We point out the key aspects of the physics and the technology that has enabled a more than 2 orders of magnitude increase in sensitivity, and as a consequence an increase in the imaging speed without loss of image quality. This speed increase provided a paradigm shift from point sampling to comprehensive 3D in vivo imaging, whose clinical impact is still actively explored by a large number of researchers worldwide.
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Affiliation(s)
- Johannes F. de Boer
- Department of Physics and Astronomy and LaserLaB Amsterdam, VU University, De Boelelaan 1105, 1081 HV Amsterdam, Department of Ophthalmology, VU Medical Center, Amsterdam, The Netherlands
- Authors are listed in alphabetical order and contributed equally
| | - Rainer Leitgeb
- Christian Doppler Laboratory OPTRAMED, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
- Authors are listed in alphabetical order and contributed equally
| | - Maciej Wojtkowski
- Physical Optics and Biophotonics Group, Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52 01-224 Warsaw, Poland
- Authors are listed in alphabetical order and contributed equally
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13
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Kandel P, Wallace MB. The Role of Adjunct Imaging in Endoscopic Detection of Dysplasia in Barrett's Esophagus. Gastrointest Endosc Clin N Am 2017; 27:423-446. [PMID: 28577765 DOI: 10.1016/j.giec.2017.02.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Advances in imaging technologies have demonstrated promise in early detection of dysplasia and cancer in Barrett's esophagus (BE). Optical chromoendoscopy, dye-based chromoendoscopy, and novel technologies have provided the opportunity to visualize the cellular and subcellular structures. Only narrow-band imaging and acetic acid chromoendoscopy have reached benchmarks for clinical use. Volumetric laser endomicroscopy and molecular imaging are not established for routine use. Best practice in management of BE should be focused on careful endoscopic examination, resection, or ablation of the entire abnormal lesion, as well as the use of available imaging technique that has good diagnostic accuracy.
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Affiliation(s)
- Pujan Kandel
- Department of Gastroenterology and Hepatology, Mayo Clinic Florida, 4500 San Pablo Road, Jacksonville, FL 32224, USA
| | - Michael B Wallace
- Department of Gastroenterology and Hepatology, Mayo Clinic Florida, 4500 San Pablo Road, Jacksonville, FL 32224, USA.
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14
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Klein T, Huber R. High-speed OCT light sources and systems [Invited]. BIOMEDICAL OPTICS EXPRESS 2017; 8:828-859. [PMID: 28270988 PMCID: PMC5330584 DOI: 10.1364/boe.8.000828] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 01/02/2017] [Accepted: 01/03/2017] [Indexed: 05/18/2023]
Abstract
Imaging speed is one of the most important parameters that define the performance of optical coherence tomography (OCT) systems. During the last two decades, OCT speed has increased by over three orders of magnitude. New developments in wavelength-swept lasers have repeatedly been crucial for this development. In this review, we discuss the historical evolution and current state of the art of high-speed OCT systems, with focus on wavelength swept light sources and swept source OCT systems.
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Affiliation(s)
- Thomas Klein
- Optores GmbH, Gollierstr. 70, 80339 Munich, Germany
| | - Robert Huber
- Institut für Biomedizinische Optik, Universität zu Lübeck, Peter-Monnik-Weg 4, 23562 Lübeck, Germany
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15
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Agrawal A, Pfefer TJ, Woolliams PD, Tomlins PH, Nehmetallah G. Methods to assess sensitivity of optical coherence tomography systems. BIOMEDICAL OPTICS EXPRESS 2017; 8:902-917. [PMID: 28270992 PMCID: PMC5330563 DOI: 10.1364/boe.8.000902] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 01/09/2017] [Accepted: 01/10/2017] [Indexed: 05/18/2023]
Abstract
Measuring the sensitivity of an optical coherence tomography (OCT) system determines the minimum sample reflectivity it can detect and provides a figure of merit for system optimization and comparison. The published literature lacks a detailed description of OCT sensitivity measurement procedures. Here we describe a commonly-used measurement method and introduce two new phantom-based methods, which also offer a means to directly visualize low reflectivity conditions relevant to biological tissue. We provide quantitative results for the three methods from different OCT system configurations and discuss the methods' advantages and disadvantages.
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Affiliation(s)
- Anant Agrawal
- Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD, USA
| | - T. Joshua Pfefer
- Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD, USA
| | - Peter D. Woolliams
- Functional Materials Group, National Physical Laboratory, Teddington, UK
| | - Peter H. Tomlins
- Barts and The London School of Medicine and Dentistry, Queen Mary University of London, E1 1BB, London, UK
| | - George Nehmetallah
- Department of Electrical Engineering and Computer Science, The Catholic University of America, Washington, DC, USA
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16
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Pande P, Shelton RL, Monroy GL, Nolan RM, Boppart SA. Low-cost hand-held probe for depth-resolved low-coherence interferometry. BIOMEDICAL OPTICS EXPRESS 2017; 8:338-348. [PMID: 28101422 PMCID: PMC5231303 DOI: 10.1364/boe.8.000338] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/07/2016] [Accepted: 12/08/2016] [Indexed: 05/20/2023]
Abstract
We report on the development of a low-cost hand-held low-coherence interferometric imaging system based on the principle of linear optical coherence tomography (Linear OCT), a technique which was first proposed in the early 2000s as a simpler alternative to the conventional time-domain and Fourier-domain OCT. A bench-top implementation of the proposed technique is first presented and validated. The axial resolution, SNR, and sensitivity roll-of of the system was estimated to be 5.2 μm and 80 dB, and 3.7 dB over a depth of 0.15 mm, respectively. After validating the bench-top system, two hand-held probe implementations for contact-based imaging and in vivo human tympanic membrane imaging are presented. The performance of the proposed system was compared with a research-grade state-of-the-art Fourier-domain low coherence interferometry (LCI) system by imaging several biological and non-biological samples. The results of this study suggest that the proposed system might be a suitable choice for applications where imaging depth and SNR can be traded for lower cost and simpler optical design.
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Affiliation(s)
- Paritosh Pande
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois,
USA
| | - Ryan L. Shelton
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois,
USA
| | - Guillermo L. Monroy
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois,
USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois,
USA
| | - Ryan M. Nolan
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois,
USA
| | - Stephen A. Boppart
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois,
USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois,
USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois,
USA
- Department of Internal Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois,
USA
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17
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Yang Y, Jiang X, Kasumie S, Zhao G, Xu L, Ward JM, Yang L, Chormaic SN. Four-wave mixing parametric oscillation and frequency comb generation at visible wavelengths in a silica microbubble resonator. OPTICS LETTERS 2016; 41:5266-5269. [PMID: 27842109 DOI: 10.1364/ol.41.005266] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Frequency comb generation in microresonators at visible wavelengths has found applications in a variety of areas such as metrology, sensing, and imaging. To achieve Kerr combs based on four-wave mixing in a microresonator, dispersion must be in the anomalous regime. In this Letter, we demonstrate dispersion engineering in a microbubble resonator (MBR) fabricated by a two-CO2 laser beam technique. By decreasing the wall thickness of the MBR to 1.4 μm, the zero dispersion wavelength shifts to values shorter than 764 nm, making phase matching possible around 765 nm. With the optical Q-factor of the MBR modes being greater than 107, four-wave mixing is observed at 765 nm for a pump power of 3 mW. By increasing the pump power, parametric oscillation is achieved, and a frequency comb with 14 comb lines is generated at visible wavelengths.
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18
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Sudkamp H, Koch P, Spahr H, Hillmann D, Franke G, Münst M, Reinholz F, Birngruber R, Hüttmann G. In-vivo retinal imaging with off-axis full-field time-domain optical coherence tomography. OPTICS LETTERS 2016; 41:4987-4990. [PMID: 27805666 DOI: 10.1364/ol.41.004987] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
With a simple setup, mainly composed of a low coherence light source and a camera, full-field optical coherence tomography (FF-OCT) allows volumetric tissue imaging. However, fringe washout constrains its use in retinal imaging. Here, we present a novel motion-insensitive approach to FF-OCT, which introduces path-length differences between the reference and the sample light in neighboring pixels using an off-axis reference beam. The temporal carrier frequency in scanned time-domain OCT is replaced by a spatial carrier frequency. Volumetric in-vivo FF-OCT measurements of the human retina were acquired in only 1.3 s, comparable to the acquisition times of current clinically used OCT devices.
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19
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Shizuka M, Hayashi N, Mizuno Y, Nakamura K. Simplified optical correlation-domain reflectometry without reference path. APPLIED OPTICS 2016; 55:3925-3928. [PMID: 27411116 DOI: 10.1364/ao.55.003925] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We develop a simplified configuration for optical correlation-domain reflectometry (OCDR) without an explicit reference path. Instead, the Fresnel-reflected light generated at the distal open end of the sensing fiber is exploited as a reference light. After the fundamental demonstration, the optimal incident power is found to be approximately 8 dBm. We also show that the loss near the distal end should not be applied, unlike in the case of Brillouin-based OCDR.
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20
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Shimada S, Shizuka M, Hayashi N, Mizuno Y, Nakamura K. Measurement of the optical path length difference in an interferometer using a sinusoidally frequency-modulated light source. APPLIED OPTICS 2016; 55:2904-2908. [PMID: 27139852 DOI: 10.1364/ao.55.002904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We develop a technique for measuring the optical path length difference (OPLD) in an interferometer using a frequency-modulated light source. Compared with conventional methods, this technique offers a high sampling rate, high precision, and cost efficiency, and is capable of determining which of the two optical paths is longer. In addition, we show that this technique works properly even when the OPLD is significantly longer than the coherence length of the light source.
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21
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Contrast-enhanced optical coherence tomography with picomolar sensitivity for functional in vivo imaging. Sci Rep 2016; 6:23337. [PMID: 26987475 PMCID: PMC4796912 DOI: 10.1038/srep23337] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 02/29/2016] [Indexed: 12/16/2022] Open
Abstract
Optical Coherence Tomography (OCT) enables real-time imaging of living tissues at cell-scale resolution over millimeters in three dimensions. Despite these advantages, functional biological studies with OCT have been limited by a lack of exogenous contrast agents that can be distinguished from tissue. Here we report an approach to functional OCT imaging that implements custom algorithms to spectrally identify unique contrast agents: large gold nanorods (LGNRs). LGNRs exhibit 110-fold greater spectral signal per particle than conventional GNRs, which enables detection of individual LGNRs in water and concentrations as low as 250 pM in the circulation of living mice. This translates to ~40 particles per imaging voxel in vivo. Unlike previous implementations of OCT spectral detection, the methods described herein adaptively compensate for depth and processing artifacts on a per sample basis. Collectively, these methods enable high-quality noninvasive contrast-enhanced imaging of OCT in living subjects, including detection of tumor microvasculature at twice the depth achievable with conventional OCT. Additionally, multiplexed detection of spectrally-distinct LGNRs was demonstrated to observe discrete patterns of lymphatic drainage and identify individual lymphangions and lymphatic valve functional states. These capabilities provide a powerful platform for molecular imaging and characterization of tissue noninvasively at cellular resolution, called MOZART.
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High Resolution Optical Coherence Tomography for Bio-Imaging. FRONTIERS IN BIOPHOTONICS FOR TRANSLATIONAL MEDICINE 2016. [DOI: 10.1007/978-981-287-627-0_6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Zhao Y, Schmidt G, Moore DT, Ellis JD. Absolute thickness metrology with submicrometer accuracy using a low-coherence distance measuring interferometer. APPLIED OPTICS 2015; 54:7693-7700. [PMID: 26368894 DOI: 10.1364/ao.54.007693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Absolute physical thickness across the sample aperture is critical in determining the index of a refraction profile from the optical path length profile for gradient index (GRIN) materials, which have a designed inhomogeneous refractive index. Motivated by this application, instrumentation was established to measure the absolute thickness of samples with nominally plane-parallel surfaces up to 50 mm thick. The current system is capable of measuring absolute thickness with 120 nm (1σ) repeatability and submicrometer expanded measurement uncertainty. Beside GRIN materials, this method is also capable of measuring other inhomogeneous and opaque materials.
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Mo J, de Groot M, de Boer JF. Depth-encoded synthetic aperture optical coherence tomography of biological tissues with extended focal depth. OPTICS EXPRESS 2015; 23:4935-4945. [PMID: 25836528 DOI: 10.1364/oe.23.004935] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Optical coherence tomography (OCT) has proven to be able to provide three-dimensional (3D) volumetric images of scattering biological tissues for in vivo medical diagnostics. Unlike conventional optical microscopy, its depth-resolving ability (axial resolution) is exclusively determined by the laser source and therefore invariant over the full imaging depth. In contrast, its transverse resolution is determined by the objective's numerical aperture and the wavelength which is only approximately maintained over twice the Rayleigh range. However, the prevailing laser sources for OCT allow image depths of more than 5 mm which is considerably longer than the Rayleigh range. This limits high transverse resolution imaging with OCT. Previously, we reported a novel method to extend the depth-of-focus (DOF) of OCT imaging in Mo et al.Opt. Express 21, 10048 (2013)]. The approach is to create three different optical apertures via pupil segmentation with an annular phase plate. These three optical apertures produce three OCT images from the same sample, which are encoded to different depth positions in a single OCT B-scan. This allows for correcting the defocus-induced curvature of wave front in the pupil so as to improve the focus. As a consequence, the three images originating from those three optical apertures can be used to reconstruct a new image with an extended DOF. In this study, we successfully applied this method for the first time to both an artificial phantom and biological tissues over a four times larger depth range. The results demonstrate a significant DOF improvement, paving the way for 3D high resolution OCT imaging beyond the conventional Rayleigh range.
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25
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Miller S, Luke K, Okawachi Y, Cardenas J, Gaeta AL, Lipson M. On-chip frequency comb generation at visible wavelengths via simultaneous second- and third-order optical nonlinearities. OPTICS EXPRESS 2014; 22:26517-26525. [PMID: 25401803 DOI: 10.1364/oe.22.026517] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Microresonator-based frequency comb generation at or near visible wavelengths would enable applications in precise optical clocks, frequency metrology, and biomedical imaging. Comb generation in the visible has been limited by strong material dispersion and loss at short wavelengths, and only very narrowband comb generation has reached below 800 nm. We use the second-order optical nonlinearity in an integrated high-Q silicon nitride ring resonator cavity to convert a near-infrared frequency comb into the visible range. We simultaneously demonstrate parametric frequency comb generation in the near-infrared, second-harmonic generation, and sum-frequency generation. We measure 17 comb lines converted to visible wavelengths extending to 765 nm.
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Tsai TH, Fujimoto JG, Mashimo H. Endoscopic Optical Coherence Tomography for Clinical Gastroenterology. Diagnostics (Basel) 2014; 4:57-93. [PMID: 26852678 PMCID: PMC4665545 DOI: 10.3390/diagnostics4020057] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 04/18/2014] [Accepted: 04/22/2014] [Indexed: 12/12/2022] Open
Abstract
Optical coherence tomography (OCT) is a real-time optical imaging technique that is similar in principle to ultrasonography, but employs light instead of sound waves and allows depth-resolved images with near-microscopic resolution. Endoscopic OCT allows the evaluation of broad-field and subsurface areas and can be used ancillary to standard endoscopy, narrow band imaging, chromoendoscopy, magnification endoscopy, and confocal endomicroscopy. This review article will provide an overview of the clinical utility of endoscopic OCT in the gastrointestinal tract and of recent achievements using state-of-the-art endoscopic 3D-OCT imaging systems.
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Affiliation(s)
- Tsung-Han Tsai
- Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - James G Fujimoto
- Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Hiroshi Mashimo
- Veterans Affairs Boston Healthcare System and Harvard Medical School, Boston, MA 02115, USA.
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Advances in optical adjunctive AIDS for visualisation and detection of oral malignant and potentially malignant lesions. Int J Dent 2013; 2013:194029. [PMID: 24078812 PMCID: PMC3775423 DOI: 10.1155/2013/194029] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 07/20/2013] [Indexed: 12/13/2022] Open
Abstract
Traditional methods of screening for oral potentially malignant disorders and oral malignancies involve a conventional oral examination with digital palpation. Evidence indicates that conventional examination is a poor discriminator of oral mucosal lesions. A number of optical aids have been developed to assist the clinician to detect oral mucosal abnormalities and to differentiate benign lesions from sinister pathology. This paper discusses advances in optical technologies designed for the detection of oral mucosal abnormalities. The literature regarding such devices, VELscope and Identafi, is critically analysed, and the novel use of Narrow Band Imaging within the oral cavity is also discussed. Optical aids are effective in assisting with the detection of oral mucosal abnormalities; however, further research is required to evaluate the usefulness of these devices in differentiating benign lesions from potentially malignant and malignant lesions.
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28
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Mo J, de Groot M, de Boer JF. Focus-extension by depth-encoded synthetic aperture in Optical Coherence Tomography. OPTICS EXPRESS 2013; 21:10048-61. [PMID: 23609710 DOI: 10.1364/oe.21.010048] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We present a novel method to extend the depth-of-focus of Optical Coherence Tomography (OCT). OCT is an interferometric imaging technique that provides depth-resolved scattering information. The axial resolution in OCT is provided by the coherence gate and is invariant over the full image depth. The lateral resolution is determined by the beam parameters such as wavelength and numerical aperture. The Rayleigh range determines the depth range over which the lateral resolution can be maintained. The lateral resolution is often sacrificed to maintain relatively long Rayleigh range. In this study, we propose to use a depth-encoded synthetic aperture detection scheme to extend the depth range over which a sharp focus can be maintained beyond the Rayleigh range. An annular phase plate is inserted into the light path in the sample arm, which gives rise to three separate images in a single B-scan, corresponding to three different optical path length encoded apertures. These three images are coherently summed after phase-manipulation to reconstruct a new image with a lateral resolution that is maintained over a five times larger depth range.
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Affiliation(s)
- Jianhua Mo
- Institute for Lasers, Life and Biophotonics Amsterdam, Department of Physics and Astronomy, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
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Kim J, Ahmad A, Boppart SA. Dual-coil magnetomotive optical coherence tomography for contrast enhancement in liquids. OPTICS EXPRESS 2013; 21:7139-7147. [PMID: 23546097 PMCID: PMC3635698 DOI: 10.1364/oe.21.007139] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 03/04/2013] [Accepted: 03/06/2013] [Indexed: 05/29/2023]
Abstract
Magnetomotive optical coherence tomography (MM-OCT) is a functional extension of OCT which utilizes magnetically responsive materials that are modulated by an external magnetic field for contrast enhancement and for elastography to assess the structural and viscoelastic properties of the surrounding tissues. Traditionally, magnetomotive contrast relies on the interaction between the displacement of magnetic particles induced by an external magnetic field and the micro-environmental restoring (elastic) force acting on the particles. When the restoring force from a sample containing magnetic particles is weak or non-existent, the MM-OCT signal-to-noise ratio (SNR) can degrade significantly. We have developed a novel solenoid configuration to enable MM-OCT imaging in samples that do not have an elastic restoring force, such as liquids. This coil configuration may potentially enable real-time MM-OCT imaging.
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Affiliation(s)
- Jongsik Kim
- University of Illinois at Urbana-Champaign, Beckman Institute for Advanced Science and Technology, 405 North Mathews Avenue, Urbana, Illinois 61801,
USA
| | - Adeel Ahmad
- University of Illinois at Urbana-Champaign, Beckman Institute for Advanced Science and Technology, 405 North Mathews Avenue, Urbana, Illinois 61801,
USA
- University of Illinois at Urbana-Champaign, Department of Electrical and Computer Engineering, 405 North Mathews Avenue, Urbana, Illinois 61801,
USA
| | - Stephen A. Boppart
- University of Illinois at Urbana-Champaign, Beckman Institute for Advanced Science and Technology, 405 North Mathews Avenue, Urbana, Illinois 61801,
USA
- University of Illinois at Urbana-Champaign, Department of Electrical and Computer Engineering, 405 North Mathews Avenue, Urbana, Illinois 61801,
USA
- University of Illinois at Urbana-Champaign, Department of Bioengineering, 405 North Mathews Avenue, Urbana, Illinois 61801,
USA
- University of Illinois at Urbana-Champaign, Department of Internal Medicine, 405 North Mathews Avenue, Urbana, Illinois 61801,
USA
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Kurokawa K, Sasaki K, Makita S, Hong YJ, Yasuno Y. Three-dimensional retinal and choroidal capillary imaging by power Doppler optical coherence angiography with adaptive optics. OPTICS EXPRESS 2012; 20:22796-812. [PMID: 23037430 DOI: 10.1364/oe.20.022796] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Retinal and choroidal vascular imaging is a key to the better understanding and diagnosis of eye diseases. To achieve comprehensive three-dimensional capillary imaging, we used an enhanced vascular imaging technique, so called adaptive optics optical coherence angiography (AO-OCA). AO-OCA enables in vivo high-resolution and high-contrast micro-vascular imaging by detecting Doppler frequency shifts. Using this technique, the retinal and choroidal vasculatures of healthy subjects were imaged. The results show that both intensity and Doppler power images have sufficient contrast to discriminate almost all vasculatures from the static tissue. However, the choriocapillaris, pre-arterioles, and post-venules in the Sattler layer were more contrasted by the Doppler technique. In conclusion, AO-OCA enables three-dimensional capillary imaging, and is especially useful for the detection of the choriocapillaris and choroidal capillary network.
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Kang JU, Huang Y, Zhang K, Ibrahim Z, Cha J, Lee WPA, Brandacher G, Gehlbach PL. Real-time three-dimensional Fourier-domain optical coherence tomography video image guided microsurgeries. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:081403-1. [PMID: 23224164 PMCID: PMC3381017 DOI: 10.1117/1.jbo.17.8.081403] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2011] [Revised: 03/03/2012] [Accepted: 03/12/2012] [Indexed: 05/20/2023]
Abstract
The authors describe the development of an ultrafast three-dimensional (3D) optical coherence tomography (OCT) imaging system that provides real-time intraoperative video images of the surgical site to assist surgeons during microsurgical procedures. This system is based on a full-range complex conjugate free Fourier-domain OCT (FD-OCT). The system was built in a CPU-GPU heterogeneous computing architecture capable of video OCT image processing. The system displays at a maximum speed of 10 volume/s for an image volume size of 160 × 80 × 1024(X × Y × Z) pixels. We have used this system to visualize and guide two prototypical microsurgical maneuvers: microvascular anastomosis of the rat femoral artery and ultramicrovascular isolation of the retinal arterioles of the bovine retina. Our preliminary experiments using 3D-OCT-guided microvascular anastomosis showed optimal visualization of the rat femoral artery (diameter<0.8 mm), instruments, and suture material. Real-time intraoperative guidance helped facilitate precise suture placement due to optimized views of the vessel wall during anastomosis. Using the bovine retina as a model system, we have performed "ultra microvascular" feasibility studies by guiding handheld surgical micro-instruments to isolate retinal arterioles (diameter ~0.1 mm). Isolation of the microvessels was confirmed by successfully passing a suture beneath the vessel in the 3D imaging environment.
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Affiliation(s)
- Jin U Kang
- Johns Hopkins University, Department of Electrical and Computer Engineering, 3400 N. Charles Street, Baltimore, MD 21218, USA.
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32
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Chen Y, Liang CP, Liu Y, Fischer AH, Parwani AV, Pantanowitz L. Review of advanced imaging techniques. J Pathol Inform 2012; 3:22. [PMID: 22754737 PMCID: PMC3385156 DOI: 10.4103/2153-3539.96751] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2012] [Accepted: 04/28/2012] [Indexed: 12/20/2022] Open
Abstract
Pathology informatics encompasses digital imaging and related applications. Several specialized microscopy techniques have emerged which permit the acquisition of digital images (“optical biopsies”) at high resolution. Coupled with fiber-optic and micro-optic components, some of these imaging techniques (e.g., optical coherence tomography) are now integrated with a wide range of imaging devices such as endoscopes, laparoscopes, catheters, and needles that enable imaging inside the body. These advanced imaging modalities have exciting diagnostic potential and introduce new opportunities in pathology. Therefore, it is important that pathology informaticists understand these advanced imaging techniques and the impact they have on pathology. This paper reviews several recently developed microscopic techniques, including diffraction-limited methods (e.g., confocal microscopy, 2-photon microscopy, 4Pi microscopy, and spatially modulated illumination microscopy) and subdiffraction techniques (e.g., photoactivated localization microscopy, stochastic optical reconstruction microscopy, and stimulated emission depletion microscopy). This article serves as a primer for pathology informaticists, highlighting the fundamentals and applications of advanced optical imaging techniques.
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Affiliation(s)
- Yu Chen
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA
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33
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Youn JI, Holcomb JD. Ablation efficiency and relative thermal confinement measurements using wavelengths 1,064, 1,320, and 1,444 nm for laser-assisted lipolysis. Lasers Med Sci 2012; 28:519-27. [PMID: 22534741 PMCID: PMC3586094 DOI: 10.1007/s10103-012-1100-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Accepted: 04/11/2012] [Indexed: 12/02/2022]
Abstract
Laser-assisted lipolysis is routinely used for contouring the body and the neck while modifications of the technique have recently been advocated for facial contouring. In this study, wavelength-dependence measurements of laser lipolysis effect were performed using different lasers at 1,064, 1,320, and 1,444 nm wavelengths that are currently used clinically. Fresh porcine skin with fatty tissue was used for the experiments with radiant exposure of 5–8 W with the same parameters (beam diameter = 600 μm, peak power = 200 mJ, and pulse rate = 40 Hz) for 1,064, 1,320 and 1,444 nm laser wavelengths. After laser irradiation, ablation crater depth and width and tissue mass loss were measured using spectral optical coherence tomography and a micro-analytical balance, respectively. In addition, thermal temporal monitoring was performed with a thermal imaging camera placed over ex vivo porcine fat tissue; temperature changes were recorded for each wavelength. This study demonstrated greatest ablation crater depth and width and mass removal in fatty tissue at the 1,444 nm wavelength followed by, in order, 1,320 and 1,064 nm. In the evaluation of heat distribution at different wavelengths, reduced heat diffusion was observed at 1,444 nm. The ablation efficiency was found to be dependent upon wavelength, and the 1,444 nm wavelength was found to provide both the highest efficiency for fatty tissue ablation and the greatest thermal confinement.
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Affiliation(s)
- Jong-In Youn
- Department of Biomedical Engineering, College of Medical Science, Catholic University of Daegu, Gyeongbuk, South Korea
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34
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Dubois A. Spectroscopic polarization-sensitive full-field optical coherence tomography. OPTICS EXPRESS 2012; 20:9962-77. [PMID: 22535089 DOI: 10.1364/oe.20.009962] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Full-field optical coherence tomography (FF-OCT) is a recent optical imaging technology based on low-coherence interference microscopy for imaging of semi-transparent samples with ~1 µm spatial resolution. FF-OCT produces en-face tomographic images obtained by arithmetic combination of interferometric images acquired by an array camera. In this paper, we demonstrate a unique multimodal FF-OCT system, capable of measuring simultaneously the intensity, the power spectrum and the phase-retardation of light backscattered by the sample being imaged. Compared to conventional FF-OCT, this multimodal system provides enhanced imaging contrasts at the price of a moderate increase in experimental complexity and cost.
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Affiliation(s)
- Arnaud Dubois
- Laboratoire Charles Fabry, Institut d’Optique, CNRS UMR 8501, Univ Paris-Sud, 2 avenue Augustin Fresnel, 91127 Palaiseau, France.
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35
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Popescu DP, Choo-Smith LP, Flueraru C, Mao Y, Chang S, Disano J, Sherif S, Sowa MG. Optical coherence tomography: fundamental principles, instrumental designs and biomedical applications. Biophys Rev 2011; 3:155. [PMID: 28510064 PMCID: PMC5418377 DOI: 10.1007/s12551-011-0054-7] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Accepted: 07/08/2011] [Indexed: 12/20/2022] Open
Abstract
The advances made in the last two decades in interference technologies, optical instrumentation, catheter technology, optical detectors, speed of data acquisition and processing as well as light sources have facilitated the transformation of optical coherence tomography from an optical method used mainly in research laboratories into a valuable tool applied in various areas of medicine and health sciences. This review paper highlights the place occupied by optical coherence tomography in relation to other imaging methods that are used in medical and life science areas such as ophthalmology, cardiology, dentistry and gastrointestinal endoscopy. Together with the basic principles that lay behind the imaging method itself, this review provides a summary of the functional differences between time-domain, spectral-domain and full-field optical coherence tomography, a presentation of specific methods for processing the data acquired by these systems, an introduction to the noise sources that plague the detected signal and the progress made in optical coherence tomography catheter technology over the last decade.
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Affiliation(s)
- Dan P Popescu
- National Research Council of Canada, Institute for Biodiagnostics, 435 Ellice Avenue, Winnipeg, MB, Canada, R3B 1Y6.
| | - Lin-P'ing Choo-Smith
- National Research Council of Canada, Institute for Biodiagnostics, 435 Ellice Avenue, Winnipeg, MB, Canada, R3B 1Y6
| | - Costel Flueraru
- National Research Council of Canada, Institute for Microstructural Sciences, 1200 Montreal Road, Ottawa, ON, Canada, K1A 0R6
| | - Youxin Mao
- National Research Council of Canada, Institute for Microstructural Sciences, 1200 Montreal Road, Ottawa, ON, Canada, K1A 0R6
| | - Shoude Chang
- National Research Council of Canada, Institute for Microstructural Sciences, 1200 Montreal Road, Ottawa, ON, Canada, K1A 0R6
| | - John Disano
- National Research Council of Canada, Institute for Microstructural Sciences, 1200 Montreal Road, Ottawa, ON, Canada, K1A 0R6
| | - Sherif Sherif
- Electrical and Computer Engineering, University of Manitoba, 75A Chancellor Drive, Winnipeg, MB, Canada, R3T 5V6
| | - Michael G Sowa
- National Research Council of Canada, Institute for Biodiagnostics, 435 Ellice Avenue, Winnipeg, MB, Canada, R3B 1Y6
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36
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Margallo-Balbás E, Geljon M, Pandraud G, French PJ. Miniature 10 kHz thermo-optic delay line in silicon. OPTICS LETTERS 2010; 35:4027-4029. [PMID: 21124601 DOI: 10.1364/ol.35.004027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The scanning delay line is a key component of time-domain optical coherence tomography systems. It has evolved since its inception toward higher scan rates and simpler implementation. However, existing approaches still suffer from drawbacks in terms of size, cost, and complexity, and they are not suitable for implementation using integrated optics. In this Letter, we report a rapid scanning delay line based on the thermo-optic effect of silicon at λ = 1.3 μm manufactured around a generic planar lightwave circuit technology. The reported device attained line scan rates of 10 kHz and demonstrated a scan range of 0.95 mm without suffering any observable loss of resolution (15 µm FWHM) owing to depth-dependent chromatic dispersion.
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37
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Kang JU, Han JH, Liu X, Zhang K, Song CG, Gehlbach P. Endoscopic Functional Fourier Domain Common Path Optical Coherence Tomography for Microsurgery. IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS : A PUBLICATION OF THE IEEE LASERS AND ELECTRO-OPTICS SOCIETY 2010; 16:781-792. [PMID: 22899880 PMCID: PMC3418670 DOI: 10.1109/jstqe.2009.2031597] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
A single-arm interferometer based optical coherence tomography (OCT) system known as common-path OCT (CPOCT) is rapidly progressing towards practical application. Due in part to the simplicity and robustness of its design, Fourier Domain CPOCT (FD-CP-OCT) offers advantages in many endoscopic sensing and imaging applications. FD-CP-OCT uses simple, interchangeable fiber optic probes that are easily integrated into small and delicate surgical tools. The system is capable of providing not only high resolution imaging but also optical sensing. Here, we report progress towards practical application of FD-CP-OCT in the setting of delicate microsurgical procedures such as intraocular retinal surgery. To meet the challenges presented by the microsurgical requirements of these procedures, we have developed and initiated the validation of applicable fiber optic probes. By integrating these probes into our developing imaging system, we have obtained high resolution OCT images and have also completed a demonstration of their potential sensing capabilities. Specifically, we utilize multiple SLEDs to demonstrate sub 3-micron axial resolution in water; we propose a technique to quantitatively evaluate the spatial distribution of oxygen saturation levels in tissue; and we present evidence supportive of the technology's surface sensing and tool guidance potential by demonstrating topological and motion compensation capabilities.
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Affiliation(s)
- Jin U Kang
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD 21218 USA (phone: 410-516-8186; fax: 410-516-5566; )
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Sun J, Guo S, Wu L, Liu L, Choe SW, Sorg BS, Xie H. 3D in vivo optical coherence tomography based on a low-voltage, large-scan-range 2D MEMS mirror. OPTICS EXPRESS 2010; 18:12065-75. [PMID: 20588329 DOI: 10.1364/oe.18.012065] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
3D in vivo optical imaging on a mouse has been obtained using a 2D MEMS mirror for lateral scanning in a time-domain optical coherence tomography (OCT) system. The MEMS mirror aperture size is 1 x 1 mm(2), and the device footprint is 2 x 2 mm(2). The MEMS mirror scans +/- 30 degrees optical angles about both x and y-axis at only 5.5V DC voltage. An endoscopic probe with an outer diameter of 5.8 mm has been designed, manufactured and packaged. The probe scans an average transverse area of 2 mm x 2 mm. The imaging speed of the probe is about 2.5 frames per second, limited by the speed of the employed optical delay line.
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Affiliation(s)
- Jingjing Sun
- Department of Electrical and Computer Engineering, University of Florida, Gainesville 32611, Florida, USA.
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Kang JU, Han JH, Liu X, Zhang K. Common-Path Optical Coherence Tomography for Biomedical Imaging and Sensing. ACTA ACUST UNITED AC 2010; 14:1-13. [PMID: 20657808 DOI: 10.3807/josk.2010.14.1.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
This paper describes a development of a fiber optic common-path optical coherence tomography (OCT) based imaging and guided system that possess ability to reliably identify optically transparent targets that are on the micron scale; ability to maintain a precise and safe position from the target; ability to provide spectroscopic imaging; ability to imaging biological target in 3-D. The system is based on a high resolution fiber optic Common-Path OCT (CP-OCT) that can be integrated into various mini-probes and tools. The system is capable of obtaining >70K A-scan per second with a resolution better than 3 μm. We have demonstrated that the system is capable of one-dimensional real-time depth tracking, tool motion limiting and motion compensation, oxygen-saturation level imaging, and high resolution 3-D images for various biomedical applications.
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Affiliation(s)
- Jin U Kang
- Department of Electrical and Computer Engineering, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
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Sacchet D, Brzezinski M, Moreau J, Georges P, Dubois A. Motion artifact suppression in full-field optical coherence tomography. APPLIED OPTICS 2010; 49:1480-8. [PMID: 20300141 DOI: 10.1364/ao.49.001480] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
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:Al(2)O(3) 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 of 0.8 microm x 1.6 microm (axial x transverse) and a detection sensitivity of approximately 60 dB.
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Affiliation(s)
- Delphine Sacchet
- Laboratoire Charles Fabry de l'Institut d'Optique, CNRS UMR 8501, Université Paris-Sud, Campus Polytechnique, RD128, 91127 Palaiseau Cedex, France.
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Wiesner M, Ihlemann J, Müller HH, Lankenau E, Hüttmann G. Optical coherence tomography for process control of laser micromachining. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:033705. [PMID: 20370183 DOI: 10.1063/1.3356080] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
In situ surface imaging for nondestructive evaluation (NDE) by optical coherence tomography (OCT) before, during, and after ablative laser processing is presented. Furthermore, it is shown that the ability of in situ characterization is beneficial for samples such as optical fibers, which are difficult to handle in the standard analysis. Surface images taken by the OCT are compared with these common analysis tools such as scanning electron microscopy (SEM), reflected-light, and confocal microscopy. An axial resolution of approximately 126 nm for surface detection and a lateral resolution <2.5 microm are obtained and the potential of the setup to imaging structures with high aspect ratio is demonstrated.
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Affiliation(s)
- Markus Wiesner
- Laser-Laboratorium Göttingen e.V., Hans-Adolf-Krebs-Weg 1, D-37077 Göttingen, Germany
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Al-Qaisi MK, Akkin T. Swept-source polarization-sensitive optical coherence tomography based on polarization-maintaining fiber. OPTICS EXPRESS 2010; 18:3392-403. [PMID: 20389349 DOI: 10.1364/oe.18.003392] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
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 conventional setups. Images of biological tissues with high dynamic range are demonstrated.
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Affiliation(s)
- Muhammad K Al-Qaisi
- Department of Biomedical Engineering, University of Minnesota, 312 Church St SE, Minneapolis, MN 55455, USA
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Testoni PA, Mangiavillano B. Optical coherence tomography for bile and pancreatic duct imaging. Gastrointest Endosc Clin N Am 2009; 19:637-53. [PMID: 19917469 DOI: 10.1016/j.giec.2009.06.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Optical coherence tomography (OCT) is an optical imaging modality introduced in 1991 that performs high-resolution, cross-sectional, subsurface tomographic imaging of the microstructure in materials and biologic systems by measuring backscattered or backreflected infrared light. OCT has been used for biomedical applications where many factors affect the feasibility and effectiveness of any imaging technique. The highly scattering and absorbing living tissues greatly limit the application of optical imaging modalities. In the last decade, OCT technology has evolved from an experimental laboratory tool to a new diagnostic imaging modality with a wide spectrum of clinical applications in medical practice, including the gastrointestinal (GI) tract and pancreaticobiliary ductal system.
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Affiliation(s)
- Pier Alberto Testoni
- Division of Gastroenterology and Gastrointestinal Endoscopy, Vita-Salute San Raffaele University, Scientific Institute San Raffaele Hospital, Via Olgettina 60, 20132 Milan, Italy.
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Testoni PA, Mangiavillano B. Optical coherence tomography in detection of dysplasia and cancer of the gastrointestinal tract and bilio-pancreatic ductal system. World J Gastroenterol 2008; 14:6444-52. [PMID: 19030194 PMCID: PMC2773328 DOI: 10.3748/wjg.14.6444] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Optical coherence tomography (OCT) is an optical imaging modality that performs high-resolution, cross-sectional, subsurface tomographic imaging of the microstructure of tissues. The physical principle of OCT is similar to that of B-mode ultrasound imaging, except that it uses infrared light waves rather than acoustic waves. The in vivo resolution is 10-25 times better (about 10 μm) than with high-frequency ultrasound imaging, but the depth of penetration is limited to 1-3 mm, depending upon tissue structure, depth of focus of the probe used, and pressure applied to the tissue surface. In the last decade, OCT technology has evolved from an experimental laboratory tool to a new diagnostic imaging modality with a wide spectrum of clinical applications in medical practice, including the gastrointestinal (GI) tract and pancreatic-biliary ductal system. OCT imaging from the GI tract can be done in humans by using narrow-diameter, catheter-based probes that can be inserted through the accessory channel of either a conventional front-view endoscope, for investigating the epithelial structure of the GI tract, or a side-view endoscope, inside a standard transparent ERCP catheter, for investigating the pancreatico-biliary ductal system. Esophagus and the esophago-gastric junction has been the most widely investigated organ so far; more recently, also duodenum, colon and pancreatico-biliary ductal system have been extensively investigated. OCT imaging of the gastro-intestinal wall structure is characterized by a multiple-layer architecture that permits an accurate evaluation of the mucosa, lamina propria, muscularis mucosae, and part of the submucosa. The technique may be, therefore, used to identify pre-neoplastic conditions of the GI tract, such as Barrett's epithelium and dysplasia, and evaluate the depth of penetration of early-stage neoplastic lesions. OCT imaging of the pancreatic and biliary ductal system could improve the diagnostic accuracy for ductal epithelial changes and the differential diagnosis between neoplastic and non-neoplastic lesions.
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Vacas-Jacques P, Paez G, Strojnik M. Pass-through photon-based biomedical transillumination. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:041307. [PMID: 19021315 DOI: 10.1117/1.2953191] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We present the mathematical foundation and the experimental validation of a technique that utilizes pass-through (ballistic) photons in a partial coherence interferometric transillumination setup for biomedical analyses. We demonstrate that the implementation depends closely on tissue under test, incident power, spatial and spectral characteristics of the radiation source, and detection electronics. With the aid of the complex material coherence function concept, we foresee tissue characterization and diagnostic imaging as potential applications for the technique. We propose a normalization procedure for in vitro and in vivo measurements, where nontissue-related quantities are canceled out. The validation of the proposal is achieved by obtaining the sample coherence function of a tissue phantom. The expected exponential attenuation is confirmed, and the corresponding scattering coefficients are determined. A good agreement between theory and experiment, for the initial set of samples, serves to establish that pass-through photon-based transillumination is feasible for selected biomedical applications.
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Affiliation(s)
- Paulino Vacas-Jacques
- Centro de Investigaciones en Optica, Apartado Postal 1-948, 37000, Leon, Guanajuato, Mexico.
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Xu W, Mathine DL, Barton JK. Analog CMOS design for optical coherence tomography signal detection and processing. IEEE Trans Biomed Eng 2008; 55:485-9. [PMID: 18269983 DOI: 10.1109/tbme.2007.905402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A CMOS circuit was designed and fabricated for optical coherence tomography (OCT) signal detection and processing. The circuit includes a photoreceiver, differential gain stage and lock-in amplifier based demodulator. The photoreceiver consists of a CMOS photodetector and low noise differential transimpedance amplifier which converts the optical interference signal into a voltage. The differential gain stage further amplifies the signal. The in-phase and quadrature channels of the lock-in amplifier each include an analog mixer and switched-capacitor low-pass filter with an external mixer reference signal. The interferogram envelope and phase can be extracted with this configuration, enabling Doppler OCT measurements. A sensitivity of -80 dB is achieved with faithful reproduction of the interferometric signal envelope. A sample image of finger tip is presented.
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Affiliation(s)
- Wei Xu
- High Performance Analog Division, Texas Instruments, Tucson, AZ 85706, USA.
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Fujimoto J, Drexler W. Introduction to Optical Coherence Tomography. OPTICAL COHERENCE TOMOGRAPHY 2008. [DOI: 10.1007/978-3-540-77550-8_1] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Park JY, Sung MS, Lee SJ. The Focal Aggravation of the Macular Edema on Optical Coherence Tomography After Intravitreal Triamcinolone Injection. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2008. [DOI: 10.3341/jkos.2008.49.5.753] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Joo Youn Park
- Department of Ophthalmology, Soonchunhyang University College of Medicine, Seoul, Korea
| | - Mi Sun Sung
- Department of Ophthalmology, Soonchunhyang University College of Medicine, Seoul, Korea
| | - Sung Jin Lee
- Department of Ophthalmology, Soonchunhyang University College of Medicine, Seoul, Korea
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Choi WS, Kim HW. The Efficacy of Verteporfin Photodynamic Therapy in Age-Related Macular Degeneration. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2008. [DOI: 10.3341/jkos.2008.49.2.274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Woo Seok Choi
- Department of Ophthalmology, Pusan Paik Hospital, College of Medicine, Inje University, Pusan, Korea
| | - Hyun Woong Kim
- Department of Ophthalmology, Pusan Paik Hospital, College of Medicine, Inje University, Pusan, Korea
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