Showing papers on "Optical coherence tomography published in 2004"
TL;DR: High-resolution spectral domain OCT is shown to provide a ~100x increase in imaging speed when compared to ultrahigh-resolution time domain OCT, and a general technique for automatic numerical dispersion compensation is presented, which is applicable to spectral domain as well as swept source embodiments of Fourier domain OCT.
Abstract: Ultrahigh-resolution optical coherence tomography uses broadband light sources to achieve axial image resolutions on the few micron scale. Fourier domain detection methods enable more than an order of magnitude increase in imaging speed and sensitivity, thus overcoming the sensitivity limitations inherent in ultrahigh-resolution OCT using standard time domain detection. Fourier domain methods also provide direct access to the spectrum of the optical signal. This enables automatic numerical dispersion compensation, a key factor in achieving ultrahigh image resolutions. We present ultrahigh-resolution, high-speed Fourier domain OCT imaging with an axial resolution of 2.1 µm in tissue and 16,000 axial scans per second at 1024 pixels per axial scan. Ultrahigh-resolution spectral domain OCT is shown to provide a ~100x increase in imaging speed when compared to ultrahigh-resolution time domain OCT. In vivo imaging of the human retina is demonstrated. We also present a general technique for automatic numerical dispersion compensation, which is applicable to spectral domain as well as swept source embodiments of Fourier domain OCT.
1,168 citations
TL;DR: The rapid development of ultrabroad bandwidth light sources has recently enabled a significant improvement in OCT imaging resolution, demonstrating the potential of OCT to accomplish its original goal of performing noninvasive optical biopsies, i.e., the in vivo visualization of microstructural morphology in situ, which had previously only been possible with histopathology.
Abstract: In the past two decades, optical coherence tomography (OCT) has been established as an adjunct diagnostic technique for noninvasive, high-resolution, cross-sectional imaging in a variety of medical fields. The rapid development of ultrabroad bandwidth light sources has recently enabled a significant improvement in OCT imaging resolution, demonstrating the potential of OCT to accomplish its original goal of performing noninvasive optical biopsies, i.e., the in vivo visualization of microstructural morphology in situ, which had previously only been possible with histopathology. In addition, these novel light sources might also enable the use of spectroscopic OCT, an extension of ultrahigh-resolution OCT, for enhancing image contrast as well as detecting spatially resolved functional, biochemical tissue information. State-of-the-art-light sources that now permit ultrahigh-resolution OCT covering the whole wavelength region from 500 to 1600 nm are reviewed and fundamental limitations of OCT image resolution are discussed. Ex vivo ultrahigh-resolution OCT tomograms are compared with histological results; first clinical in vivo ultrahigh-resolution OCT and preliminary spectroscopic OCT results are presented and their impact for future clinical and research applications is discussed.
701 citations
TL;DR: 3-dimensional data sets were collected in 11 and 13 seconds for the macula and optic nerve head respectively and are presented to demonstrate the potential clinical applications of SD-OCT in ophthalmology.
Abstract: An ultra-high-speed spectral-domain optical coherence tomography system (SD-OCT) was developed for imaging the human retina and optic nerve in vivo at a sustained depth profile (A-line) acquisition speed of 29 kHz. The axial resolution was 6 µm in tissue and the system had shot-noise-limited performance with a maximum sensitivity of 98.4 dB. 3-dimensional data sets were collected in 11 and 13 seconds for the macula and optic nerve head respectively and are presented to demonstrate the potential clinical applications of SD-OCT in ophthalmology. Additionally, a 3-D volume of the optic nerve head was constructed from the acquired data and the retinal vascular network was visualized.
687 citations
TL;DR: An ultrahigh-speed spectral domain optical coherence tomography (SD-OCT) system is presented, demonstrating the ability to acquire high-quality structural images with an axial resolution of 6 microm at ultrahigh speed and with an ocular exposure level of less than 600 microW.
Abstract: An ultrahigh-speed spectral domain optical coherence tomography (SD-OCT) system is presented that achieves acquisition rates of 29,300 depth profiles/s. The sensitivity of SD-OCT and time domain OCT (TD-OCT) are experimentally compared, demonstrating a 21.7-dB improvement of SD-OCT over TD-OCT. In vivo images of the human retina are presented, demonstrating the ability to acquire high-quality structural images with an axial resolution of 6 microm at ultrahigh speed and with an ocular exposure level of less than 600 microW.
643 citations
TL;DR: With this new system, two layers at the location of the retinal pigmented epithelium seem to be present, as well as small features in the inner and outer plexiform layers, which are believed to be small blood vessels.
Abstract: We present the first ultrahigh-resolution optical coherence tomography (OCT) structural intensity images and movies of the human retina in vivo at 29.3 frames per second with 500 A-lines per frame. Data was acquired at a continuous rate of 29,300 spectra per second with a 98% duty cycle. Two consecutive spectra were coherently summed to improve sensitivity, resulting in an effective rate of 14,600 A-lines per second at an effective integration time of 68 micros. The turn-key source was a combination of two super luminescent diodes with a combined spectral width of more than 150 nm providing 4.5 mW of power. The spectrometer of the spectraldomain OCT (SD-OCT) setup was centered around 885 nm with a bandwidth of 145 nm. The effective bandwidth in the eye was limited to approximately 100 nm due to increased absorption of wavelengths above 920 nm in the vitreous. Comparing the performance of our ultrahighresolution SD-OCT system with a conventional high-resolution time domain OCT system, the A-line rate of the spectral-domain OCT system was 59 times higher at a 5.4 dB lower sensitivity. With use of a software based dispersion compensation scheme, coherence length broadening due to dispersion mismatch between sample and reference arms was minimized. The coherence length measured from a mirror in air was equal to 4.0 microm (n= 1). The coherence length determined from the specular reflection of the foveal umbo in vivo in a healthy human eye was equal to 3.5 microm (n = 1.38). With this new system, two layers at the location of the retinal pigmented epithelium seem to be present, as well as small features in the inner and outer plexiform layers, which are believed to be small blood vessels. ?2004 Optical Society of America.
585 citations
TL;DR: Visualization of intra-retinal layers, especially the inner and outer segment of the photoreceptor layer, obtained by FDOCT was comparable to that, accomplished by ultrahigh resolution time domain OCT, despite an at least 40 times higher data acquisition speed of FD OCT.
Abstract: We present, for the first time, in vivo ultrahigh resolution (~2.5 μm in tissue), high speed (10000 A-scans/second equivalent acquisition rate sustained over 160 A-scans) retinal imaging obtained with Fourier domain (FD) OCT employing a commercially available, compact (500×260mm), broad bandwidth (120 nm at full-width-at-half-maximum centered at 800 nm) Titanium:sapphire laser (Femtosource Integral OCT, Femtolasers Produktions GmbH). Resolution and sampling requirements, dispersion compensation as well as dynamic range for ultrahigh resolution FD OCT are carefully analyzed. In vivo OCT sensitivity performance achieved by ultrahigh resolution FD OCT was similar to that of ultrahigh resolution time domain OCT, although employing only 2–3 times less optical power (~300 μW). Visualization of intra-retinal layers, especially the inner and outer segment of the photoreceptor layer, obtained by FDOCT was comparable to that, accomplished by ultrahigh resolution time domain OCT, despite an at least 40 times higher data acquisition speed of FD OCT.
529 citations
TL;DR: A white-light interference microscope for ultrahigh-resolution full-field optical coherence tomography of biological media and subcellular-level images of plant, animal, and human tissues are presented.
Abstract: We have developed a white-light interference microscope for ultrahigh-resolution full-field optical coherence tomography of biological media. The experimental setup is based on a Linnik-type interferometer illuminated by a tungsten halogen lamp. En face tomographic images are calculated by a combination of interferometric images recorded by a high-speed CCD camera. Spatial resolution of 1.8 μm × 0.9 μm (transverse × axial) is achieved owing to the extremely short coherence length of the source, the compensation of dispersion mismatch in the interferometer arms, and the use of relatively high-numerical-aperture microscope objectives. A shot-noise-limited detection sensitivity of 90 dB is obtained in an acquisition time per image of 4 s. Subcellular-level images of plant, animal, and human tissues are presented.
483 citations
TL;DR: OCT is a non-invasive imaging technique that has been used increasingly to diagnose and manage a variety of retinal diseases and glaucoma as discussed by the authors, and it can be used to identify and quantify macular edema, and to measure retinal thickness changes in response to therapy.
448 citations
TL;DR: Results of theoretical and experimental investigations of artifacts that can arise in spectral-domain optical coherence tomography (SD-OCT) and optical frequency domain imaging (OFDI) as a result of sample or probe beam motion are described.
Abstract: We describe results of theoretical and experimental investigations of artifacts that can arise in spectral-domain optical coherence tomography (SD-OCT) and optical frequency domain imaging (OFDI) as a result of sample or probe beam motion. While SD-OCT and OFDI are based on similar spectral interferometric principles, the specifics of motion effects are quite different because of distinct signal acquisition methods. These results provide an understanding of motion artifacts such as signal fading, spatial distortion and blurring, and emphasize the need for fast image acquisition in biomedical applications.
424 citations
Journal Article•
TL;DR: Merging of ultrahigh-resolution optical coherence tomography (UHR OCT) and adaptive optics (AO), resulting in high axial and transverse resolution and a significant signal-to-noise ratio improvement of up to 9 dB in corrected compared with uncorrected OCT tomograms is achieved.
Abstract: Merging of ultrahigh-resolution optical coherence tomography (UHR OCT) and adaptive optics (AO), resulting in high axial (3 microm) and improved transverse resolution (5-10 microm) is demonstrated for the first time to our knowledge in in vivo retinal imaging. A compact (300 mm x 300 mm) closed-loop AO system, based on a real-time Hartmann-Shack wave-front sensor operating at 30 Hz and a 37-actuator membrane deformable mirror, is interfaced to an UHR OCT system, based on a commercial OCT instrument, employing a compact Ti:sapphire laser with 130-nm bandwidth. Closed-loop correction of both ocular and system aberrations results in a residual uncorrected wave-front rms of 0.1 microm for a 3.68-mm pupil diameter. When this level of correction is achieved, OCT images are obtained under a static mirror configuration. By use of AO, an improvement of the transverse resolution of two to three times, compared with UHR OCT systems used so far, is obtained. A significant signal-to-noise ratio improvement of up to 9 dB in corrected compared with uncorrected OCT tomograms is also achieved.
351 citations
TL;DR: In this article, a closed-loop correction of both ocular and system aberrations results in a residual uncorrected wavefront rms of 0.1 µm for a 3.68 mm pupil diameter.
Abstract: Merging of ultrahigh-resolution optical coherence tomography (UHR OCT) and adaptive optics (AO), resulting in high axial (3 µm) and improved transverse resolution (5–10 µm) is demonstrated for the first time to our knowledge in in vivo retinal imaging. A compact (300 mm×300 mm) closed-loop AO system, based on a real-time Hartmann–Shack wave-front sensor operating at 30 Hz and a 37-actuator membrane deformable mirror, is interfaced to an UHR OCT system, based on a commercial OCT instrument, employing a compact Ti:sapphire laser with 130-nm bandwidth. Closed-loop correction of both ocular and system aberrations results in a residual uncorrected wave-front rms of 0.1 µm for a 3.68-mm pupil diameter. When this level of correction is achieved, OCT images are obtained under a static mirror configuration. By use of AO, an improvement of the transverse resolution of two to three times, compared with UHR OCT systems used so far, is obtained. A significant signal-to-noise ratio improvement of up to 9 dB in corrected compared with uncorrected OCT tomograms is also achieved.
TL;DR: Spectral Optical Coherence Tomography provides a much wider safety margin than the traditional method and allows relaxation of the current safety precautions forbidding more than 10 minutes/day scanning of the same location of a retina.
TL;DR: Combining the previously described structural and Doppler imaging functions with polarization-sensitive imaging increases the utility of the technique for rapid, non-invasive investigations in the skin.
TL;DR: An analysis for polarization-sensitive optical coherence tomography that facilitates the unrestricted use of fiber and fiber-optic components throughout an interferometer and yields sample birefringence, diattenuation, and relative optic axis orientation is presented.
Abstract: We present an analysis for polarization-sensitive optical coherence tomography that facilitates the unrestricted use of fiber and fiber-optic components throughout an interferometer and yields sample birefringence, diattenuation, and relative optic axis orientation. We use a novel Jones matrix approach that compares the polarization states of light reflected from the sample surface with those reflected from within a biological sample for pairs of depth scans. The incident polarization alternated between two states that are perpendicular in a Poincare sphere representation to ensure proper detection of tissue birefringence regardless of optical fiber contributions. The method was validated by comparing the calculated diattenuation of a polarizing sheet, chicken tendon, and muscle with that obtained by independent measurement. The relative importance of diattenuation versus birefringence to angular displacement of Stokes vectors on a Poincare sphere was quantified.
TL;DR: In this paper, a single scattering model and a recently developed description of the confocal point spread function (PSF) were used to extract the attenuation coefficient with an accuracy of 0.8 mm-1.
Abstract: From calibrated, weakly scattering tissue phantoms (2-6 mm-1), we extract the attenuation coefficient with an accuracy of 0.8 mm-1 from OCT data in the clinically relevant 'fixed focus' geometry. The data are analyzed using a single scattering model and a recently developed description of the confocal point spread function (PSF). We verify the validity of the single scattering model by a quantitative comparison with a multiple scattering model, and validate the use of the PSF on the calibrated samples. Implementation of this model for existing OCT systems will be straightforward. Localized quantitative measurement of the attenuation coefficient of different tissues can significantly improve the clinical value of OCT.
TL;DR: The possibility of measuring a full Doppler flow depth profile in parallel by use of frequency-domain optical coherence tomography is demonstrated and the method is based on a local phase analysis of the backscattered signal and allows for imaging of bidirectional Dopplers flow.
Abstract: The possibility of measuring a full Doppler flow depth profile in parallel by use of frequency-domain optical coherence tomography is demonstrated. The method is based on a local phase analysis of the backscattered signal and allows for imaging of bidirectional Doppler flow. The Doppler frequency limit is 5 kHz for the presented measurements and is set by half of the frame rate of the CCD detector array. We measured the flow of 0.3‐µm microspheres suspended in distilled water at controlled flow rates and in vitro human blood flow through a 200‐µm capillary with a real-time color-encoded Doppler tomogram rate of 2–3/s.
TL;DR: Comparison of CLSM and OCT suggests that the same fibrous layer is imaged by the two techniques, and this layer might be due to the transition between the papillary and reticular dermis.
Abstract: Skin structure and age-related changes in human skin were characterized in vivo by applying confocal laser scanning microscopy (CLSM) and optical coherence tomography (OCT). The overall effect of aging skin, derived from studies of volunteers belonging to two age groups, was found to be a significant decrease in the maximum thickness of the epidermis and flattening of the dermo-epidermal junction. At a certain depth in the dermis, well below the basal layer, a reflecting layer of fibrous structure is observed in CLSM images. The location of this layer strongly depends on age and is situated much deeper below the skin surface in younger than in older skin. In addition, large structural changes were observed with age. The OCT images show two bright reflecting layers. The first one is due to scattering at the skin surface. The second band appears to be caused by a layer of fibrous structure in the dermis. Direct comparison of CLSM and OCT suggests that the same fibrous layer is imaged by the two techniques. This layer might be due to the transition between the papillary and reticular dermis. A comparison of CLSM and OCT enables a better understanding of the images.
TL;DR: The results illustrate the potential of OCT for a wide range of basic research studies and for intra-operative image-guidance to identify foci of tumor cells within surgical margins during the surgical treatment of breast cancer.
Abstract: Diagnostic trends in medicine are being directed toward cellular and molecular processes, where treatment regimens are more amenable for cure. Optical imaging is capable of performing cellular and molecular imaging using the short wavelengths and spectroscopic properties of light. Diffuse optical tomography is an optical imaging technique that has been pursued as an alternative to X-ray mammography. While this technique permits non-invasive optical imaging of the whole breast, to date it is incapable of resolving features at the cellular level. Optical coherence tomography (OCT) is an emerging high-resolution biomedical imaging technology that for larger and undifferentiated cells can perform cellular-level imaging at the expense of imaging depth. OCT performs optical ranging in tissue and is analogous to ultrasound except reflections of near-infrared light are detected rather than sound. In this paper, an overview of the OCT technology is provided, followed by images demonstrating the feasibility of using OCT to image cellular features indicative of breast cancer. OCT images of a well-established carcinogen-induced rat mammary tumor model were acquired. Images from this common experimental model show strong correlation with corresponding histopathology. These results illustrate the potential of OCT for a wide range of basic research studies and for intra-operative image-guidance to identify foci of tumor cells within surgical margins during the surgical treatment of breast cancer.
TL;DR: In this paper, the angular compounding by path length encoding (ACPE) algorithm is proposed to reduce speckle in OCT images by averaging images obtained at different incident angles, with each image encoded by the path length.
Abstract: Speckle, a factor reducing image quality in optical coherence tomography ('OCT'), can limit the ability to identify cellular structures that are important for the diagnosis of a variety of diseases. The present invention allows for an implementation of an angular compounding, angular compounding by path length encoding ('ACPE') for reducing speckle in OCT images. By averaging images obtained at different incident angles, with each image encoded by path length, ACPE maintains high-speed image acquisition and implements minimal modifications to OCT probe optics. ACPE images obtained from tissue phantoms and human skin in vivo demonstrate a qualitative improvement over traditional OCT and an increased signal-to-noise ratio ('SNR'). Accordingly, apparatus probe catheter, and method are provided for irradiating a sample. In particular, an interferometer (5) may forward forwarding an electromagnetic radiation (10). In addition, a sample arm may receive the electromagnetic radiation, and can include an arrangement (20) which facilitates a production of at least two radiations (30, 40) from the electromagnetic radiation so as to irradiate the sample. Such arrangement can be configured to delay a first radiation of the at least two radiations with respect to a second radiation of the at least two radiations.
TL;DR: A swept source based polarization-sensitive Fourier domain optical coherence tomography (FDOCT) system was developed that can acquire the Stokes vectors, polarization diversity intensity and birefringence images in biological tissue by reconstruction of both the amplitude and phase terms of the interference signal.
Abstract: A swept source based polarization-sensitive Fourier domain optical coherence tomography (FDOCT) system was developed that can acquire the Stokes vectors, polarization diversity intensity and birefringence images in biological tissue by reconstruction of both the amplitude and phase terms of the interference signal. The Stokes vectors of the reflected and backscattered light from the sample were determined by processing the analytical complex fringe signals from two perpendicular polarizationdetection channels. Conventional time domain OCT (TDOCT) and spectrometer based FDOCT systems are limited by the fact that the input polarization states are wavelength dependent. The swept source based FDOCT system overcomes this limitation and allows accurate setting of the input polarization states. From the Stokes vectors for two different input polarization states, the polarization diversity intensity and birefringence images were obtained.
TL;DR: In this article, a high-speed dynamic focus control system based on a microelectromechanical mirror was designed to maintain high transverse resolution over the entire depth scan, which can yield sub-optimal lateral resolution outside the focal zone for deep-imaging OCT systems.
TL;DR: P polarization-sensitive optical coherence tomography (OCT) images of human skin in vivo are presented, demonstrating the ability of the technique to visualize and quantify the birefringent properties of skin.
Abstract: Optical coherence tomography enables cross-sectional imaging of tissue structure to depths of around 1.5 mm, at high-resolution and in real time. Incorporation of polarization sensitivity (PS) provides an additional contrast mechanism which is complementary to images mapping backscattered intensity only. We present here polarization-sensitive optical coherence tomography (OCT) images of human skin in vivo, demonstrating the ability of the technique to visualize and quantify the birefringent properties of skin. Variation in normal skin birefringence according to anatomical location is demonstrated, and discussed in relation to collagen distribution at each location. From measurements on a sample of five human volunteers, mean double-pass phase retardation rates of 0.340+/-0.143, 0.250+/-0.076, and 0.592+/-0.142 deg/microm were obtained for the dorsal hand, temple, and lower back regions, respectively. We demonstrate how averaging the Stokes parameters of backscattered light over a range of axial and lateral dimensions results in a reduction of speckle-induced noise. Examples of PS-OCT images from skin sites following wound healing and repair are also presented and discussed.
TL;DR: A miniature endoscope that is capable of rapid lateral scanning and is suitable for real-time forward-imaging optical coherence tomography (OCT) and operated in the new image acquisition sequence at 6 frames/s is demonstrated.
Abstract: We developed a miniature endoscope that is capable of rapid lateral scanning and is suitable for real-time forward-imaging optical coherence tomography (OCT). The endoscope has an outer diameter of 2.4 mm, consisting of a miniature tubular lead zirconate titanate (PZT) actuator, a single-mode fiber-optic cantilever, and a graded-index lens. Rapid lateral scanning at 2.8 kHz is achieved when the fiber-optic cantilever is resonated with the PZT actuator. This allows OCT imaging to be performed by fast lateral beam scanning followed by slow depth scanning, which is different from the conventional OCT imaging sequence. Real-time OCT imaging with the endoscope operated in the new image acquisition sequence at 6 frames/s is demonstrated.
TL;DR: There was a significant correlation between the features of optical coherence tomography and fluorescein angiography in clinically significant diabetic macular edema and the combined data may provide a clearer understanding of the anatomic and physiologic characteristics of clinically significant insulin-dependent diabetes.
TL;DR: Optical coherence tomography is very useful in distinguishing MPH attributable to epiretinal membrane contraction from LMH because of partial opening of a macular cyst from other cases corresponding to LMH.
TL;DR: The increased resolution of UHR-OCT enables the visualization of photoreceptor morphology associated with macular hole pathology and postoperative repair and promises to lead to a better understanding of the pathogenesis of macular holes, the causes of visual loss secondary to macular Hole, the timing of surgical repair, and the evaluation of postsurgical outcome.
Patent•
09 Dec 2004TL;DR: In this paper, a system for tomographic imaging includes a source of at least partially coherent radiation, a frequency-swept laser source and an interferometer, which is phase modulated at a modulation frequency for elimination of DC and autocorrelation noises as well as the mirror image.
Abstract: A system for tomographic imaging includes a source of at least partially coherent radiation, a frequency-swept laser source and an interferometer. The radiation in the interferometer is phase modulated at a modulation frequency for elimination of DC and autocorrelation noises as well as the mirror image. The interference fringes of the radiation backscattered from the sample into the interferometer are detected to obtain a spectral signal. The spectral signal of the detected backscattered interference fringes is transformed to obtain a location dependent signal at each pixel location in a data window. A tomographic image of the fluid flow in the data window is generated for display and of the structure of the scanned fluid flow sample in the data window from the location dependent signal is generated.
TL;DR: Significant agreement between contact lens examination and OCT for the detection of diabetic foveal edema is poor when OCT thickening is mild, which suggests that contact lens biomicroscopy is relatively insensitive for the Detection of mildfoveal thickening apparent on OCT.
Abstract: Objective To compare contact lens biomicroscopy with optical coherence tomography(OCT) for the detection of diabetic foveal edema. Methods Study participants consisted of a convenient cohort of consecutive patientswith diabetes mellitus seen at the Wilmer Eye Institute's Retinal VascularCenter, Baltimore, Md. Case characteristics were recorded and eyes were examinedby 1 of 4 retina specialists by means of contact lens biomicroscopy. Edemainvolving the center of the macula was assessed as definitely present, questionablypresent, or definitely not present. The OCT testing was performed and interpretedby trained technicians, masked to the physicians' assessment of foveal edema.Agreement between OCT and contact lens examination for the absence or presenceof foveal edema was evaluated. Results One hundred seventy-two eyes of 95 patients with diabetes were enrolledin August and September 2002. Foveal thickness was objectively measured byOCT in 170 (99%) of 172 cases. We found excellent agreement between OCT andcontact lens examination for the absence or presence of foveal edema whenOCT thickness was normal (≤200 µm) or moderately to severely increased(>300 µm). However, agreement was poor when foveal thickness was mildlyincreased on OCT (201-300 µm). Conclusions Agreement between contact lens examination and OCT for the detectionof diabetic foveal edema is poor when OCT thickening is mild. This suggeststhat contact lens biomicroscopy is relatively insensitive for the detectionof mild foveal thickening apparent on OCT. Additional studies are needed toinvestigate the natural course of cases with mildly increased foveal thicknesson OCT that do not appear thickened clinically.
TL;DR: It is concluded that this algorithm may facilitate tissue characterization by OCT because it was possible to extract both the scattering coefficient and anisotropy factor from a particular region of interest in an OCT image.
Abstract: We developed a new algorithm that fits optical coherence tomography (OCT) signals as a function of depth to a general theoretical OCT model which takes into account multiple scattering effects. With use of this algorithm, it was possible to extract both the scattering coefficient and anisotropy factor from a particular region of interest in an OCT image. The extraction algorithm was evaluated against measurements from an integrating sphere on a set of tissue phantoms and yielded valid results. Finally, a preliminary ex vivo OCT investigation on human aortic specimen indicated that the algorithm may contribute importantly to differentiation between normal and atherosclerotic arteries. We conclude that this algorithm may facilitate tissue characterization by OCT.
Patent•
17 Feb 2004
TL;DR: In this article, a 3D fringe pattern is generated by the interference of light emitted and collected by the fibers, and the pattern is scanned dynamically over the object by phase shift delays controlled remotely, near ends of the fibers opposite the tips of the fiber, and combined with light modulation.
Abstract: Optical coherence tomography with 3D coherence scanning is disclosed, using at least three fibers ( 201, 202, 203 ) for object illumination and collection of backscattered light. Fiber tips ( 1, 2, 3 ) are located in a fiber tip plane ( 71 ) normal to the optical axis ( 72 ). Light beams emerging from the fibers overlap at an object ( 122 ) plane, a subset of intersections of the beams with the plane defining field of view ( 266 ) of the optical coherence tomography apparatus. Interference of light emitted and collected by the fibers creates a 3D fringe pattern. The 3D fringe pattern is scanned dynamically over the object by phase shift delays ( 102, 104 ) controlled remotely, near ends of the fibers opposite the tips of the fibers, and combined with light modulation. The dynamic fringe pattern is backscattered by the object, transmitted to a light processing system ( 108 ) such as a photo detector, and produces an AC signal on the output of the light processing system ( 108 ). Phase demodulation of the AC signal at selected frequencies and signal processing produce a measurement of a 3D profile of the object.