1. Articles from Vijaysekhar Jayaraman

    1-24 of 45 1 2 »
    1. Spectrally shaped tunable short-cavity laser

      Spectrally shaped tunable short-cavity laser

      A tunable source includes a short-cavity laser optimized for performance and reliability in SSOCT imaging systems, spectroscopic detection systems, and other types of detection and sensing systems. The short cavity laser has a large free spectral range cavity, fast tuning response and single transverse, longitudinal and polarization mode operation, and includes embodiments for fast and wide tuning, and optimized spectral shaping. Disclosed are both electrical and optical pumping in a MEMS-VCSEL geometry with mirror and gain regions optimized for wide tuning, high output power, and a variety of preferred wavelength ranges; and a semiconductor optical amplifier, combined with the short-cavity ...

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    2. Agile imaging system

      Agile imaging system

      An agile optical imaging system for optical coherence tomography imaging using a tunable source comprising a wavelength tunable VCL laser is disclosed. The tunable source has long coherence length and is capable of high sweep repetition rate, as well as changing the sweep trajectory, sweep speed, sweep repetition rate, sweep linearity, and emission wavelength range on the fly to support multiple modes of OCT imaging. The imaging system also offers new enhanced dynamic range imaging capability for accommodating bright reflections. Multiscale imaging capability allows measurement over orders of magnitude dimensional scales. The imaging system and methods for generating the waveforms ...

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    3. Feature Of The Week 10/08/2018: Clinical Utility of Ultrahigh-Speed Endoscopic Optical Coherence Tomography in Gastroenterology

      Feature Of The Week 10/08/2018: Clinical Utility of Ultrahigh-Speed Endoscopic Optical Coherence Tomography in Gastroenterology

      Barrett’s esophagus (BE) surveillance is limited by biopsy sampling error. Optical coherence tomography (OCT) enables microscopic resolution, high speed, volumetric imaging and is commercially available as volumetric laser endomicroscopy (VLE, NinePoint Medical). Studies investigated cross-sectional OCT dysplasia features, including a diagnostic algorithm (VLE-DA), however, many VLE studies used ex vivo specimens due to challenges in registering biopsy with OCT. We previously demonstrated ultrahigh-speed endoscopic OCT >10x faster than commercial instruments, enabling depth-resolved en face and cross-sectional imaging. This study investigated volumetric en face and cross-sectional OCT for identifying neoplasia. 74 OCT datasets with correlated biopsy/endoscopic mucosal resection histology ...

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    4. Assessment of Barrett’s esophagus and dysplasia with ultrahigh-speed volumetric en face and cross-sectional optical coherence tomography

      Assessment of Barrett’s esophagus and dysplasia with ultrahigh-speed volumetric en face and cross-sectional optical coherence tomography

      Background  This study aimed to evaluate the use of ultrahigh-speed volumetric en face and cross-sectional optical coherence tomography (OCT) with micromotor catheters for the in vivo assessment of Barrett’s esophagus and dysplasia. Methods  74 OCT datasets with correlated biopsy/endoscopic mucosal resection histology (49 nondysplastic Barrett’s esophagus [NDBE], 25 neoplasia) were obtained from 14 patients with Barrett’s esophagus and a history of dysplasia and 30 with NDBE. The associations between irregular mucosal patterns on en face OCT, absence of mucosal layering, surface signal > subsurface, and > 5 atypical glands on cross-sectional OCT vs. histology and treatment history were ...

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    5. Microscope-Integrated Intraoperative Ultrahigh-Speed Swept-Source Optical Coherence Tomography for Widefield Retinal and Anterior Segment Imaging

      Microscope-Integrated Intraoperative Ultrahigh-Speed Swept-Source Optical Coherence Tomography for Widefield Retinal and Anterior Segment Imaging

      BACKGROUND AND OBJECTIVE: To demonstrate the feasibility of retinal and anterior segment intraoperative widefield imaging using an ultrahigh-speed, swept-source optical coherence tomography (SS-OCT) surgical microscope attachment. PATIENTS AND METHODS: A prototype post-objective SS-OCT using a 1,050-nm wavelength, 400 kHz A-scan rate, vertical cavity surface-emitting laser (VCSEL) light source was integrated to a commercial ophthalmic surgical microscope after the objective. Each widefield OCT data set was acquired in 3 seconds (1,000 × 1,000 A-scans, 12 × 12 mm 2 for retina and 10 × 10 mm 2 for anterior segment). RESULTS: Intraoperative SS-OCT was performed in 20 eyes of 20 patients ...

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    6. Cycloid scanning for wide field optical coherence tomography endomicroscopy and angiography in vivo

      Cycloid scanning for wide field optical coherence tomography endomicroscopy and angiography in vivo

      Devices that perform wide field-of-view (FOV) precision optical scanning are important for endoscopic assessment and diagnosis of luminal organ disease such as in gastroenterology. Optical scanning for in vivo endoscopic imaging has traditionally relied on one or more proximal mechanical actuators, limiting scan accuracy and imaging speed. There is a need for rapid and precise two-dimensional (2D) microscanning technologies to enable the translation of benchtop scanning microscopies to in vivo endoscopic imaging. We demonstrate a new cycloid scanner in a tethered capsule for ultrahigh speed, side-viewing optical coherence tomography (OCT) endomicroscopy in vivo . The cycloid capsule incorporates two scanners: a ...

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    7. Widely tunable short cavity laser

      Widely tunable short cavity laser

      A tunable source includes a short-cavity laser optimized for performance and reliability in SSOCT imaging systems, spectroscopic detection systems, and other types of detection and sensing systems. The short cavity laser has a large free spectral range cavity, fast tuning response and single transverse, longitudinal and polarization mode operation, and includes embodiments for fast and wide tuning, and optimized spectral shaping. Disclosed are both electrical and optical pumping in a MEMS-VCSEL geometry with mirror and gain regions optimized for wide tuning, high output power, and a variety of preferred wavelength ranges; and a semiconductor optical amplifier, combined with the short-cavity ...

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    8. Ultrahigh-speed endoscopic optical coherence tomography and angiography enables delineation of lateral margins of endoscopic mucosal resection: a case report

      Ultrahigh-speed endoscopic optical coherence tomography and angiography enables delineation of lateral margins of endoscopic mucosal resection: a case report

      Endoscopic mucosal resection (EMR) is a common technique for resecting dysplastic lesions in Barrett’s esophagus (BE), stomach, and colon, 1 but precise delineation of dysplastic margins before resection and verification of complete removal after resection remain challenging. 2 , 3 Endoscopic optical coherence tomography (OCT) enables three-dimensional visualization of tissue microstructure and is commercially available as Volumetric Laser Endomicroscopy (NinePoint Medical, Bedford, MA, USA). 4 , 5 We recently developed an ultrahigh-speed endoscopic OCT system which operates more than 10 times faster than commercial instruments, generating volumetric images with higher transverse resolution and voxel density. 6 , 7 This allows visualization of ...

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    9. Endoscopic forward-viewing optical coherence tomography and angiography with MHz swept source

      Endoscopic forward-viewing optical coherence tomography and angiography with MHz swept source

      Endoscopic optical coherence tomography (OCT) instruments are mostly side viewing and rely on at least one proximal scan, thus limiting accuracy of volumetric imaging and en face visualization. Previous forward-viewing OCT devices had limited axial scan speeds. We report a forward-viewing fiber scanning 3D-OCT probe with 900 μm field of view and 5 μm transverse resolution, imaging at 1 MHz axial scan rate in the human gastrointestinal tract. The probe is 3.3 mm diameter and 20 mm rigid length, thus enabling passage through the endoscopic channel. The scanner has 1.8 kHz resonant frequency, and each volumetric acquisition takes ...

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    10. Cubic meter volume optical coherence tomography

      Cubic meter volume optical coherence tomography

      Optical coherence tomography (OCT) is a powerful three-dimensional (3D) imaging modality with micrometer-scale axial resolution and up to multi-GigaVoxel/s imaging speed. However, the imaging range of high-speed OCT has been limited. Here, we report 3D OCT over cubic meter volumes using a long coherence length, 1310 nm vertical-cavity surface-emitting laser and silicon photonic integrated circuit dual-quadrature receiver technology combined with enhanced signal processing. We achieved 15 μm depth resolution for tomographic imaging at a 100 kHz axial scan rate over a 1.5 m range. We show 3D macroscopic imaging examples of a human mannequin, bicycle, machine shop gauge ...

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    11. Volumetric Mapping of Barrett’s Esophagus and Dysplasia With en face Optical Coherence Tomography Tethered Capsule

      Volumetric Mapping of Barrett’s Esophagus and Dysplasia With en face Optical Coherence Tomography Tethered Capsule

      To the Editor: Dysplasia in Barrett’s Esophagus (BE) is patchy ( 1 ) and sometimes missed by random biopsies. Optical coherence tomography (OCT) can image large areas of the esophagus; however, slow imaging speeds in earlier studies limited visualization to cross-sections. Cross-sectional OCT detected high-grade dysplasia with sensitivity / specificity of ~80 % ( 2 , 3 ). Tethered OCT capsules were demonstrated for cross-sectional imaging in unsedated screening to detect BE ( 4 , 5 ). Our group recently developed ultrahigh-speed OCT for en face and angiographic imaging, using micromotor probes in patients ( 6 , 7 ) and large field-of-view tethered capsule devices in swine ( 8 ). Narrow-band imaging (NBI) visualizes ...

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    12. ULTRAHIGH SPEED SWEPT SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY OF RETINAL AND CHORIOCAPILLARIS ALTERATIONS IN DIABETIC PATIENTS WITH AND WITHOUT RETINOPATHY

      ULTRAHIGH SPEED SWEPT SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY OF RETINAL AND CHORIOCAPILLARIS ALTERATIONS IN DIABETIC PATIENTS WITH AND WITHOUT RETINOPATHY

      Purpose: To investigate the utility of ultrahigh speed, swept source optical coherence tomography angiography in visualizing retinal microvascular and choriocapillaris (CC) changes in diabetic patients. Methods: The study was prospective and cross-sectional. A 1,050 nm wavelength, 400 kHz A-scan rate swept source optical coherence tomography prototype was used to perform volumetric optical coherence tomography angiography of the retinal and CC vasculatures in diabetic patients and normal subjects. Sixty-three eyes from 32 normal subjects, 9 eyes from 7 patients with proliferative diabetic retinopathy, 29 eyes from 16 patients with nonproliferative diabetic retinopathy, and 51 eyes from 28 diabetic patients without ...

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    13. Choroidal Neovascularization Analyzed on Ultrahigh-Speed Swept-Source Optical Coherence Tomography Angiography Compared to Spectral-Domain Optical Coherence Tomography Angiography

      Choroidal Neovascularization Analyzed on Ultrahigh-Speed Swept-Source Optical Coherence Tomography Angiography Compared to Spectral-Domain Optical Coherence Tomography Angiography

      Purpose To compare visualization of choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD) using an ultrahigh-speed swept-source (SS) optical coherence tomography angiography (OCTA) prototype vs a spectral-domain (SD) OCTA device. Design Comparative analysis of diagnostic instruments. Methods Patients were prospectively recruited to be imaged on SD OCT and SS OCT devices on the same day. The SD OCT device employed is the RTVue Avanti (Optovue, Inc, Fremont, California, USA), which operates at ∼840 nm wavelength and 70 000 A-scans/second. The SS OCT device used is an ultrahigh-speed long-wavelength prototype that operates at ∼1050 nm wavelength and 400 000 ...

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    14. Amplified widely tunable short cavity laser

      Amplified widely tunable short cavity laser

      An amplified tunable source includes a short-cavity laser coupled to an optical amplifier for high power, spectrally shaped operation. The short-cavity laser is coupled to a quantum well semiconductor optical amplifier with two quantum states for broadened gain. Two preferred wavelength ranges of the amplified tunable source include 1200-1400 nm and 800-1100 nm. Also disclosed is the short cavity tunable laser coupled to a fiber amplifier. Various combinations of tunable optical filters with the amplified tunable source to reduce noise or improve spectral purity are presented.

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    15. Tunable short cavity laser sensor

      Tunable short cavity laser sensor

      Optical systems employ a tunable source which includes a short cavity laser with a large free spectral range cavity, fast tuning response, and single transverse and longitudinal mode operation. Systems for optical spectroscopy with optimized scanning, a system for optical beam steering and a system for a tunable local oscillator are disclosed.

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    16. Polarization stable widely tunable short cavity laser

      Polarization stable widely tunable short cavity laser

      A tunable source includes a short-cavity laser optimized for performance and reliability in SSOCT imaging systems, spectroscopic detection systems, and other types of detection and sensing systems. A short cavity laser with a large free spectral range cavity, fast tuning response and single transverse, longitudinal and polarization mode operation is disclosed. Methods for obtaining polarization stable operation of the tunable source are presented.

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    17. Circumferential optical coherence tomography angiography imaging of the swine esophagus using a micromotor balloon catheter

      Circumferential optical coherence tomography angiography imaging of the swine esophagus using a micromotor balloon catheter

      We demonstrate a micromotor balloon imaging catheter for ultrahigh speed endoscopic optical coherence tomography (OCT) which provides wide area, circumferential structural and angiographic imaging of the esophagus without contrast agents. Using a 1310 nm MEMS tunable wavelength swept VCSEL light source, the system has a 1.2 MHz A-scan rate and ~8.5 µm axial resolution in tissue. The micromotor balloon catheter enables circumferential imaging of the esophagus at 240 frames per second (fps) with a ~30 µm (FWHM) spot size. Volumetric imaging is achieved by proximal pullback of the micromotor assembly within the balloon at 1.5 mm/sec ...

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    18. Choroidal neovascularization analyzed on ultra-high speed swept source optical coherence tomography angiography compared to spectral domain optical coherence tomography angiography

      Choroidal neovascularization analyzed on ultra-high speed swept source optical coherence tomography angiography compared to spectral domain optical coherence tomography angiography

      Purpose To compare visualization of choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD) using an ultra-high speed swept-source (SS)-optical coherence tomography angiography (OCTA) prototype versus a spectral-domain (SD)-OCTA device. Design Comparative analysis of diagnostic instruments. Methods Patients were prospectively recruited to be imaged on SD-OCT and SS-OCT devices on the same day. The SD-OCT device employed is the RTVue Avanti that operates at ∼840nm wavelength and 70,000 A-scans/second. The SS-OCT device used is an ultra-high speed long-wavelength prototype that operates at ∼1050nm wavelength and 400,000 A-scans/second. Two observers independently measured the CNV area ...

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    19. Ultrahigh-Speed, Swept-Source Optical Coherence Tomography Angiography in Nonexudative Age-Related Macular Degeneration with Geographic Atrophy

      Ultrahigh-Speed, Swept-Source Optical Coherence Tomography Angiography in Nonexudative Age-Related Macular Degeneration with Geographic Atrophy

      Purpose To investigate ultrahigh-speed, swept-source optical coherence tomography (SSOCT) angiography for visualizing vascular changes in eyes with nonexudative age-related macular degeneration (AMD) with geographic atrophy (GA). Design Observational, prospective, cross-sectional study. Participants A total of 63 eyes from 32 normal subjects and 12 eyes from 7 patients with nonexudative AMD with GA. Methods A 1050-nm, 400-kHz A-scan rate SSOCT system was used to perform volumetric optical coherence tomography angiography (OCTA) of the retinal and choriocapillaris (CC) vasculatures in normal subjects and patients with nonexudative AMD with GA. Optical coherence tomography angiography using variable interscan time analysis (VISTA) was performed to ...

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    20. Wideband Electrically Pumped 1050-nm MEMS-Tunable VCSEL for Ophthalmic Imaging

      Wideband Electrically Pumped 1050-nm MEMS-Tunable VCSEL for Ophthalmic Imaging

      In this paper, we present a 1050-nm electrically pumped microelectromechanically tunable vertical cavity surface emitting laser (MEMS-VCSEL) with a record dynamic tuning bandwidth of 63.8 nm, suitable for swept-source optical coherence tomography (SS-OCT) imaging. These devices provide reduced cost and complexity relative to previously demonstrated optically pumped devices by obviating the need for a pump laser and associated hardware. We demonstrate ophthalmic SS-OCT imaging with the electrically-pumped MEMS-VCSEL at a 400 kHz axial scan rate for wide-field imaging of the in vivo human retina over a 12 mm × 12 mm field and for OCT angiography of the macula over ...

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    21. Feature Of The Week 03/08/2015: Endoscopic Optical Coherence Angiography Enables Three Dimensional Visualization of Subsurface Microvasculature

      Feature Of The Week 03/08/2015: Endoscopic Optical Coherence Angiography Enables Three Dimensional Visualization of Subsurface Microvasculature

      Endoscopic imaging technologies such as confocal laser endomicroscopy (CLE) and narrowband imaging (NBI) have been used to investigate vascular changes as hallmarks of early cancer in the GI tract. However, the limited frame rate and field of view make CLE imaging sensitive to motion artifacts, whereas NBI has limited resolution and visualizes only the surface vascular pattern. Endoscopic optical coherence tomography (OCT) enables high speed volumetric imaging of subsurface features at near-microscopic resolution, and can image microvasculature without exogenous contrast agents such as fluorescein, which obliterates the image in areas of bleeding, or after biopsies and resections. OCT has been ...

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    22. Ultrahigh speed en face OCT capsule for endoscopic imaging

      Ultrahigh speed en face OCT capsule for endoscopic imaging

      Depth resolved and en face OCT visualization in vivo may have important clinical applications in endoscopy. We demonstrate a high speed, two-dimensional (2D) distal scanning capsule with a micromotor for fast rotary scanning and a pneumatic actuator for precision longitudinal scanning. Longitudinal position measurement and image registration were performed by optical tracking of the pneumatic scanner. The 2D scanning device enables high resolution imaging over a small field of view and is suitable for OCT as well as other scanning microscopies. Large field of view imaging for screening or surveillance applications can also be achieved by proximally pulling back or ...

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    23. Wideband Electrically-Pumped 1050 nm MEMS-Tunable VCSEL for Ophthalmic Imaging

      Wideband Electrically-Pumped 1050 nm MEMS-Tunable VCSEL for Ophthalmic Imaging

      In this paper, we present a 1050 nm electricallypumped micro-electro-mechanically-tunable vertical-cavitysurface- emitting-laser (MEMS-VCSEL) with a record dynamic tuning bandwidth of 63.8 nm, suitable for swept source optical coherence tomography (SS-OCT) imaging. These devices provide reduced cost & complexity relative to previously demonstrated optically pumped devices by obviating the need for a pump laser and associated hardware. We demonstrate ophthalmic SS-OCT imaging with the electrically-pumped MEMS-VCSEL at a 400 kHz axial scan rate for wide field imaging of the in vivo human retina over a 12 mm × 12 mm field and for OCT angiography of the macula over 6 mm × 6 ...

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    24. Ultrahigh-Speed Swept-Source OCT Angiography in Exudative AMD

      Ultrahigh-Speed Swept-Source OCT Angiography in Exudative AMD

      BACKGROUND AND OBJECTIVE: To investigate the potential of ultrahigh-speed swept-source optical coherence tomography angiography (OCTA) to visualize retinal and choroidal vascular changes in patients with exudative age-related macular degeneration (AMD). PATIENTS AND METHODS: Observational, prospective cross-sectional study. An ultrahigh-speed swept-source prototype was used to perform OCTA of the retinal and choriocapillaris microvasculature in 63 eyes of 32 healthy controls and 19 eyes of 15 patients with exudative AMD. MAIN OUTCOME MEASURE: qualitative comparison of the retinal and choriocapillaris microvasculature in the two groups. RESULTS: Choroidal neovascularization (CNV) was clearly visualized in 16 of the 19 eyes with exudative AMD, located ...

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    High power broadband superluminescent diode MEMS tunable VCSEL light source for ultrahigh speed 60kHz - 1MHz axial scan rate and long range centimeter class OCT imaging 1065nm and 1310nm MEMS tunable VCSEL light source technology for OCT imaging Retinal, anterior segment and full eye imaging using ultrahigh speed swept source OCT with vertical-cavity surface emitting lasers Phase-sensitive swept-source optical coherence tomography imaging of the human retina with a vertical cavity surface-emitting laser light source Ultrahigh speed endoscopic optical coherence tomography using micro-motor imaging catheter and VCSEL technology Feature Of The Week 4/2/14: A Compact High-Performance Hand-Held Device for Extending Ophthalmic OCT to New Points of Care (Narrated Presentation) Ultrahigh-Speed Swept-Source OCT Angiography in Exudative AMD Feature Of The Week 03/08/2015: Endoscopic Optical Coherence Angiography Enables Three Dimensional Visualization of Subsurface Microvasculature Correlation between optical coherence tomography, multifocal electroretinogram findings and visual acuity in diabetic macular edema Ciliary body length revisited by anterior segment optical coherence tomography: implications for safe access to the pars plana for intravitreal injections Evaluation of retinal vascular structure after epiretinal membrane surgery by optical coherence tomography angiography