Tunable Sources -Optical Coherence Tomography News

Articles in category: Tunable Sources

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1. Ultra-broadband wavelength-swept Ti:sapphire crystal fiber laser
  
  Explore Optica Publishing Group Jun 2 2022 Tunable Sources
  
  An ultra-broadband wavelength-swept laser (WSL) was generated using glass-clad Ti:sapphire crystal fiber as the gain media. Due to the low signal propagation loss of the crystal fiber, the swept laser has a tuning bandwidth of 250 nm (i.e., 683 nm to 933 nm) at a repetition rate of 1200 Hz. The steady-state and pulsed dynamics of the WSL were analyzed. The 0.018-nm instantaneous linewidth corresponds to a 3-dB coherence roll-off of 7 mm. When using the laser for swept-source optical coherence tomography, an estimated axial resolution of 1.8 µm can be achieved.
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  Mentions: National Taiwan University
2. Fourier Domain Mode Locked Laser and Its Applications
  
  Explore MDPI Open Access Journals Platform May 28 2022 Tunable Sources
  
  The sweep rate of conventional short-cavity lasers with an intracavity-swept filter is limited by the buildup time of laser signals from spontaneous emissions. The Fourier domain mode-locked (FDML) laser was proposed to overcome the limitations of buildup time by inserting a long fiber delay in the cavity to store the whole swept signal and has attracted much interest in both theoretical and experimental studies. In this review, the theoretical models to understand the dynamics of the FDML laser and the experimental techniques to realize high speed, wide sweep range, long coherence length, high output power and highly stable swept signals ...
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  Mentions: Hong Kong Polytechnic University
3. Linewidth considerations for MEMS tunable VCSEL LiDAR
  
  Explore Optica Publishing Group May 4 2022 Tunable Sources
  
  The flexible membranes used in MEMS tunable VCSELs are so small and light that thermally induced vibrations can impact laser performance. We measure the thermal vibration spectrum of such a membrane showing peaks at the spatial vibration mode resonant frequencies of the membrane/plate. These vibrations result in a theoretical floor to the linewidth of the VCSEL. Frequency domain LiDAR and optical coherence tomography systems can get around this thermal linewidth limit with adequate clock measurement and processing. Essentially an OCT/LiDAR sweep with a concomitantly measured clock is a feed-forward linewidth reduction scheme. This can be achieved because the ...
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  Mentions: Axsun Technologies
4. Swept frequency photonic integrated circuit for absolute metrology
  
  Explore uspto.gov May 3 2022 Patents , Tunable Sources
  
  A digital measuring device implemented on a photonic integrated circuit, the digital measuring device including a tunable laser source implemented on the photonic integrated circuit configured to sweep over a frequency range to provide multi-wavelength light, a first waveguide structure implemented on the photonic integrated circuit configured to direct a first portion of light from the laser source at a moving object and receive light reflected from the moving object, a second waveguide structure implemented on the photonic integrated circuit configured to combine a second portion of light from the laser source with the light reflected from the moving object ...
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5. Swept Source-Optical Coherence Tomography Using New Recalibration Method for Nonlinear Sweeping Laser
  
  Explore KoreaScience Apr 21 2022 Tunable Sources
  
  In this paper, Frequency Domain Mode Locked (FDML) wavelength swept laser with 55.027 kHz sweeping speed and 125 nm sweeping range has realized, and also a new method for recalibrating a nonlinear frequency sweeping of a swept laser has proposed. The Swept Source-Optical Coherence Tomography system using the proposed method has performed. For a mirror surface, the system showed the very clean 2-dimensional image and the advanced image speed of 7 frames per sec compared to the previous recalibration method.
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6. RF properties of circular-ranging OCT signals
  
  Explore Optica Publishing Group Apr 4 2022 Tunable Sources
  
  Circular-ranging optical coherence tomography (CR–OCT) systems that use a time–stepped frequency comb source generate interference fringe signals that are more complex than those of a conventional swept–source OCT system. Here, we define a common terminology for describing these signals, and we develop a mathematical framework that relates the radio-frequency (RF) properties of these fringe signals to the parameters of the frequency comb source. With this framework, we highlight non-intuitive mechanisms whereby the design of the frequency comb source can affect imaging performance. We show, for example, that amplitude–pulsed time–stepped frequency comb sources have a sensitivity ...
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  Mentions: Massachusetts General Hospital Harvard University
7. External-cavity laser diode using acousto-optic deflector as tunable grating
  
  Explore Optica Publishing Group Apr 2 2022 Tunable Sources
  
  In this study, a novel, to the best of our knowledge, external-cavity laser diode (ECLD) without a diffraction grating is proposed and demonstrated. In the proposed configuration, an acousto-optic deflector (AOD) acts not only as a deflector but also as a diffraction grating. Thus, the AOD functions as a wavelength-selective device, which helps improve the overall performance of the ECLD. In fact, the proposed configuration realizes a wide range of wavelength scanning with a simple configuration, highly efficient optical feedback, and a steady optical resonator with a constant cavity length. We confirm that the wavelengths scanned with the proposed ECLD ...
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8. Precisely controlled chirped diode laser and coherent lidar system
  
  Explore uspto.gov Mar 15 2022 Patents , Tunable Sources
  
  Frequency modulated lasers, LIDAR systems, and methods of controlling laser are disclosed. A laser source emits an optical beam having an optical frequency that changes in response to a signal applied to an input of the laser source. A laser driver that generates the signal applied to the input to cause the optical frequency to vary in accordance with a periodic frequency versus time function.
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9. Method for monitoring time-dependent properties of light during scanning swept-source optical coherence tomography
  
  Explore uspto.gov Mar 1 2022 Patents , Tunable Sources
  
  A method comprises: splitting laser light into sample light, reference light, and monitor light; routing the reference light into a reference arm of an OCT interferometer; routing the monitor light into a monitor device, which generates at least one optical monitor signal representing at least one time-dependent property of the monitor light; generating at least one electric monitor signal from the at least one optical monitor signal; illuminating in a point-shaped manner a sample with sample light, wherein the illumination point is guided on the surface of the sample along a predetermined trajectory; superimposing the light scattered by the sample ...
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  Mentions: Optores
10. Broadband wavelength swept laser with bidirectional photonic resonance for high resolution optical coherence tomography
  
  Explore IEEE Xplore Jan 14 2022 Tunable Sources
  
  A light source with extended spectral bandwidth applied in optical coherence tomography (OCT) systems produces highly accurate micro - scale imaging structures owing to the attainable high - axial resolution. This study presents a wide tuning range of a wavelength - swept laser to improve the axial resolution. Linear cavity configuration was performed for bidirectional photonic resonance using two semiconductor optical amplifiers placed parallelly. A polygon scanner - based tunable filter produced a broa d scanning range of 155 nm from 917 nm to 1072 nm and an axial resolution of 3.4 μm in air. Bench - top imaging of a phantom made of ...
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11. Widely tunable short-cavity laser
  
  Explore uspto.gov Nov 23 2021 Patents , Tunable Sources
  
  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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  Mentions: Thorlabs
12. Swept light source and drive data generation method and optical deflector for swept light source
  
  Explore uspto.gov Nov 2 2021 Patents , Tunable Sources
  
  A swept light source of the present invention keeps a coherence length of an output beam long over an entire sweep wavelength range. A gain of a gain medium is changed with time in response to a wavelength sweep and the coherence length is kept maximum. The gain of the gain medium is kept close to a lasing threshold and an unsaturated gain range of the gain medium is narrowed over the entire sweep wavelength range.
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  Mentions: NTT
13. Information processing apparatus, information processing method, and storage medium
  
  Explore uspto.gov Oct 19 2021 Patents , Tunable Sources
  
  An information processing apparatus including an acquisition unit configured to acquire a first three-dimensional optical coherence tomography (OCT) image of a target eye, and a display control unit configured to display, on a display unit, the first three-dimensional OCT image and an interface configured to receive an instruction for acquiring a second three-dimensional OCT image of the target eye, which is an image captured with a fixation target position the same as a fixation target position used in capturing the first three-dimensional OCT image and is to be combined with the first three-dimensional OCT image. 2015/0342456 December 2015 Yamashita ...
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  Mentions: Canon Medical Systems
14. Systems, methods, and media for multiple reference arm spectral domain optical coherence tomography
  
  Explore uspto.gov Sep 14 2021 Patents , Tunable Sources
  
  In some embodiments, systems, methods, and media for multiple reference arm spectral domain optical coherence tomography are provided which, in some embodiments, includes: a sample arm coupled to a light source; a first reference arm having a first path length; a second reference arm having a longer second path length; a first optical coupler that combines light from the sample arm and the first reference arm; a second coupler that combines light from the sample arm and the second reference arm; and an optical switch comprising: a first input port coupled to the first optical coupler; a second input coupled ...
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  Mentions: Massachusetts General Hospital Harvard University Wasatch Photonics
15. MEMS-VCSEL as a tunable light source for OCT imaging of long working distance
  
  Explore SPIE Digital Library Sep 7 2021 Tunable Sources
  
  We present a wavelength tunable vertical-cavity surface-emitting laser (VCSEL) constructed by die-bonding a half-cavity InGaAs laser diode (LD) chip onto a silicon-on-insulator chip with a microelectromechanical system electrostatic diaphragm mirror that functions as a Fabry–Perot interferometer. As a result of the short cavity length, the integrated tunable LD has single-mode lasing characteristics with an extremely large coherence length of 150 m or more. The developed wavelength tunable LD is used to perform swept-source optical coherence tomography with a large scan depth, which is applicable to ophthalmic observation for the diagnosis of pathologic nearsightedness based on the measurement of the ...
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  Mentions: Santec
16. Robust and easy-to-operate stretched-pulse mode-locked wavelength-swept laser with an all-polarization-maintaining fiber cavity for 10 MHz A-line rate optical coherence tomography
  
  Explore OSA | OSA Publishing Aug 4 2021 Tunable Sources
  
  We demonstrate robust and easy-to-operate stretched-pulse mode-locked laser (SPML) architectures using all-polarization-maintaining fiber laser cavities. Because of the polarization-maintaining construction, the laser performance is unaffected by mechanical perturbation on the cavity fibers. The lasers automatically initiate linear-in-wavenumber sweeps across 100 nm centered at 1290 nm with a 10 MHz repetition rate. OCT imaging with a sensitivity of 98 dB and a single-sided 6 dB coherence length of 2.5 mm is demonstrated. OCT angiography of a mouse brain that visualized three-dimensional cerebral microvasculature over a field of 1.5 m m × 1.5 m m 1.5mm×1.5mm (398 ...
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  Mentions: Massachusetts General Hospital Harvard University Korea Advanced Institute of Science and Technology
17. Carl Zeiss Meditec Takes Insight Photonics Solutions to Court for Breach of Contract Seeking $150M in Damages
  
  Explore Optical Coherence Tomography News Jul 27 2021 Other Business News , Tunable Sources
  
  UNITED STATES DISTRICT COURT SOUTHERN DISTRICT OF NEW YORK CARL ZEISS MEDITEC, INC., Civil Action No. Plaintiff, Complaint v. INSIGHT PHOTONICS SOLUTIONS, INC., Defendant. Plaintiff Carl Zeiss Meditec, Inc. ("Zeiss"), by its attorneys, Dorsey & Whitney LLP, for its Complaint against Defendant Insight Photonics Solutions, Inc. ("Insight"), states as follows: INTRODUCTION 1. This action arises out of Insight's willful and bad faith breaches of a 2017 development agreement (the "Development Agreement") by and among Zeiss, Insight, and a joint venture between Zeiss and Insight, called Ophthalmic Laser Engines, LLC ("OLE"). Under the Development Agreement, Insight was obligated to develop ophthalmic ...
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  Mentions: Carl Zeiss Meditec Insight Photonic Solutions
18. Tunable semiconductor slotted lasers for near-infrared Optical Coherence Tomography
  
  Explore IEEE Xplore Jul 25 2021 Tunable Sources
  
  The use of Optical Coherence Tomography in the field of clinical diagnosis is significant. There are different types of swept source lasers available on the market today, however, their design and associated complex fabrication process increase their cost. In the work presented here, an economical six-section slotted tunable laser operating near 850 nm has been designed and fabricated using a UV optical lithography process. The laser is monolithically integrable without a need for any regrowth step. Initial characterization has confirmed the high quality of the slot geometry and stable single mode operation within its tuning range.
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  Mentions: University College Cork
19. Anrtisu Introduces a New Swept Light Source
  
  Explore Optical Coherence Tomography News Jul 5 2021 Other Business News , Tunable Sources
  
  Anritsu released the swept light source for OCT applications on 1st July 2021. More information can be found in the following links. https://www.anritsu.com/en-US/sensing-devices/products/swept-light-source Anritsu Wavelength Swept Light Source Operation Principles and OFDR Measurement Application Document Anritsu Wavelength Swept Light Source Measurement Applications Document
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  Mentions: Anritsu Corporation
20. Wavelength tunable laser device using frequency shifter
  
  Explore uspto.gov Jun 22 2021 Patents , Tunable Sources
  
  A wavelength tunable laser device includes a gain element positioned in an optical cavity that provides optical gain to an optical signal. A frequency shifter that generates a frequency shift as a function of time is positioned in the optical cavity. The optical cavity is configured so that a magnitude of the frequency shift as a function of time generated by the frequency shifter is substantially equal to a frequency separation of a cavity mode of the cavity such that an output of the cavity generates laser light having a wavelength that tunes as a function of time.
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21. Cavity length control for Fourier domain mode locked (FDML) lasers with µm precision
  
  Explore OSA | OSA Publishing Jun 14 2021 Tunable Sources
  
  In highly dispersion compensated Fourier domain mode locked (FDML) lasers, an ultra-low noise operation can only be achieved by extremely precise and stable matching of the filter tuning period and light circulation time in the cavity. We present a robust and high precision closed-loop control algorithm and an actively cavity length controlled FDML laser. The cavity length control achieves a stability of ∼0.18 mHz at a sweep repetition rate of ∼418 kHz which corresponds to a ratio of 4×10 −10 . Furthermore, we prove that the rapid change of the cavity length has no negative impact on the quality ...
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  Mentions: University of Lübeck
22. Multi-MHz MEMS-VCSEL swept-source optical coherence tomography for endoscopic structural ...
  
  Explore OSA | OSA Publishing Mar 26 2021 Gastroenterology , Probes , Tunable Sources
  
  Swept source optical coherence tomography (SS-OCT) enables volumetric imaging of subsurface structure. However, applications requiring wide fields of view (FOV), rapid imaging, and higher resolutions have been challenging because multi-MHz axial scan (A-scan) rates are needed. We describe a microelectromechanical systems vertical cavity surface-emitting laser (MEMS-VCSEL) SS-OCT technology for A-scan rates of 2.4 and 3.0 MHz. Sweep to sweep calibration and resampling are performed using dual channel acquisition of the OCT signal and a Mach Zehnder interferometer signal, overcoming inherent optical clock limitations and enabling higher performance. We demonstrate ultrahigh speed structural SS-OCT and OCT angiography (OCTA) imaging ...
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  Mentions: Massachusetts Institute of Technology National Institutes of Health Thorlabs
23. Tunable VCSEL polarization control through dissimilar die bonding
  
  Explore uspto.gov Mar 16 2021 Patents , Tunable Sources
  
  A design and method for introducing asymmetric crystal strain to control polarization in a tunable VCSEL, either optically or electrically pumped. The invention is especially relevant to wafer- or die-bonded tunable VCSELs. Then, mechanical stress is applied to the half VCSEL device by asymmetric arrangement of metal bond pads.
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  Mentions: Axsun Technologies
24. Optically pumped tunable VCSEL employing geometric isolation
  
  Explore uspto.gov Mar 16 2021 Patents , Tunable Sources
  
  An optically pumped tunable VCSEL swept source module has a VCSEL and a pump, which produces light to pump the VSCEL, wherein the pump is geometrically isolated from the VCSEL. In different embodiments, the pump is geometrically isolated by defocusing light from the pump in front of the VCSEL, behind the VCSEL, and/or by coupling the light from the pump at an angle with respect to the VCSEL. In the last case, angle is usually less than 88 degrees. There are further strategies for attacking pump noise problems. Pump feedback can be reduced through (1) Faraday isolation and (2 ...
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  Mentions: Axsun Technologies
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