1. Queen's University Canada

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    1. Mentioned In 14 Articles

    2. Methods and systems for characterizing laser machining properties by measuring keyhole dynamics using interferometry

      Methods and systems for characterizing laser machining properties by measuring keyhole dynamics using interferometry
      A method, apparatus, and system are provided to monitor and characterize the dynamics of a phase change region (PCR) created during laser welding, specifically keyhole welding, and other material modification processes, using low-coherence interferometry. By directing a measurement beam to multiple locations within and overlapping with the PCR, the system, apparatus, and method are used to determine, in real time, spatial and temporal characteristics of the weld such as keyhole ...
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    3. West Nile Virus Chorioretinitis With Foveal Involvement Evolution of Lesions on Optical Coherence Tomography

      West Nile Virus Chorioretinitis With Foveal Involvement Evolution of Lesions on Optical Coherence Tomography
      Purpose: To describe the clinical course of foveal West Nile virus (WNV) chorioretinitis with longitudinal spectral domain optical coherence tomography (SD-OCT) imaging. Methods: Case report. Results: A 41-year-old man with diabetes mellitus presented with flashes and floaters of both eyes (OU) and decreased vision of the right eye (OD) 2 weeks after being discharged from a local hospital. He had been treated for WNV meningoencephalitis, and he recovered systemically with ...
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    4. Spectral domain optical coherence tomography-guided versus 1-week facedown-posturing after macular hole surgery

      Spectral domain optical coherence tomography-guided versus 1-week facedown-posturing after macular hole surgery
      Objective To compare idiopathic full-thickness macular hole (FTMH) closure rates and postoperative best-corrected visual acuity (BCVA) between spectral domain optical coherence tomography (SD-OCT)guided facedown posturing and conventional 1-week facedown posturing after macular hole surgery. Design A retrospective comparative study. Participants Thirty-one consecutive eyes that underwent surgery for FTMH between July 2013 and September 2014 were divided into 2 groups. Methods In the SD-OCT-guided group, SD-OCT was performed on the ...
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    5. Methods and systems for coherent imaging and feedback control for modification of materials

      Methods and systems for coherent imaging and feedback control for modification of materials
      Methods and systems are provided for using optical interferometry in the context of material modification processes such as surgical laser or welding applications. An imaging optical source that produces imaging light. A feedback controller controls at least one processing parameter of the material modification process based on an interferometry output generated using the imaging light. A method of processing interferograms is provided based on homodyne filtering. A method of generating ...
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    6. Spectral-domain optical coherence tomography in mitochondrial encephalopathy, lactic acidosis, and strokelike episodes

      Spectral-domain optical coherence tomography in mitochondrial encephalopathy, lactic acidosis, and strokelike episodes
      The point mutation in mitochondrial DNA (mtDNA) 3243AG is associated with many clinical disorders such as MELAS (mitochondrial encephalomyopathy with lactic acidosis and stroke like episodes) and MIDD (maternally inherited diabetes and deafness). 1 MELAS is characterized by strokelike episodes with headache, episodic nausea and vomiting, and lactic acidosis. Other findings include renal failure, neurosensory hearing loss, diabetes mellitus, and short stature. 1 Ocular findings include pigmentary retinopathy, retinal pigment ...
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    7. Inline Coherent Imaging (Thesis)

      Inline Coherent Imaging (Thesis)
      In laser materials processing, the direct measurement and characterization of material and process depth is traditionally a diffcult task. This is particularly difficult when such information needs to be obtained in real-time for feedback and dynamic analysis applications. This thesis outlines a novel method and apparatus for real-time depth measurement during laser processes such as welding, drilling, cutting and ablation called inline coherent imaging (ICI). The approach borrows the coherent ...
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    8. Scientists create laser similar to Star Wars light sabre

      Scientists create laser similar to Star Wars light sabre
      A team of medical and physics experts developed a groundbreaking technique that significantly improves laser accuracy to the point where cutting can be controlled to stop at a precise point — comparable to the idea of a Star Wars light sabre. Specifically, the team has demonstrated that they can stop the laser within 50 microns — or half the diameter of a human hair. “A major problem that’s really hindering laser ...
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    9. Real-time guidance of thermal and ultrashort pulsed laser ablation in hard tissue using inline coherent imaging

      Real-time guidance of thermal and ultrashort pulsed laser ablation in hard tissue using inline coherent imaging
      Abstract Background and Objective During tissue ablation, laser light can be delivered with high precision in the transverse dimensions but final incision depth can be difficult to control. We monitor incision depth as it progresses, providing feedback to ensure that material removal occurs within a localized target volume, reducing the possibility of undesirable damage to tissues below the incision. Materials and Methods Ex vivo cortical and cancellous bone was ablated ...
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    10. Contrast improvement in Fourier-domain optical coherence tomography through time gating

      Time-gated (TG) Fourier-domain optical coherence tomography (FDOCT) exploits interferometric imaging with incoherent gating to filter out unwanted backreflections and improve contrast. The system uses sum-frequency generation with a variable length optical pulse as a “time gate” to restrict the depth field of view of backscattered light to 84-176 μm (−20 dB points). The imaging bandwidth is upconverted from the IR (1280 nm) to visible (504 nm), which allows the use ...
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    11. The association between multifocal electroretinograms and OCT retinal thickness in retinitis pigmentosa patients with good visual acuity

      Aims To investigate relationships between retinal morphology and retinal function in patients with retinitis pigmentosa (RP) using optical coherence tomography (OCT) and multifocal electroretinography (mfERG). Methods In all, 14 patients with RP who had visual acuities of 0.2|[thinsp]|logMAR or better and Humphrey central fields of 10|[deg]| or larger participated in the study along with 16 normal control subjects. The amplitudes and timings of the mfERG responses ...
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    12. Effect of prophylactic nonsteroidal antiinflammatory drugs on cystoid macular edema assessed using optical coherence tomography quantification of total macular volume after cataract surgery.

      Related Articles Effect of prophylactic nonsteroidal antiinflammatory drugs on cystoid macular edema assessed using optical coherence tomography quantification of total macular volume after cataract surgery. J Cataract Refract Surg. 2008 Jan;34(1):64-69 Authors: Almeida DR, Johnson D, Hollands H, Smallman D, Baxter S, Eng KT, Kratky V, Ten Hove MW, Sharma S, El-Defrawy S PURPOSE: To evaluate the efficacy of prophylactic administration of the topical nonsteroidal antiinflammatory drug ...
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    13. Time-gated Fourier-domain optical coherence tomography

      A novel optical coherence tomography (OCT) system is presented that combines Fourier-domain OCT with incoherent nonlinear time gating. By processing backscattered light in the optical domain, the user can select a restricted depth field of view for improved contrast and acquisition speed. This ... [Opt. Lett. 32, 3336-3338 (2007)]
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    14. High speed in situ depth profiling of ultrafast micromachining

      We demonstrate real-time depth profiling of ultrafast micromachining of stainless steel at scan rates of 46 kHz. The broad bandwidth and high power of the light source allows for simultaneous machining and coaxial Fourier-domain interferometric imaging of the ablation surface with depth resolutions ... [Opt. Express 15, 14967-14972 (2007)]
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  2. About Queen's University Canada

    Queen's University Canada

    Queen's University Canada is one of Canada's leading universities, with an international reputation for scholarship, research, social purpose, spirit and diversity. Consistently highly-ranked, Queen's is known for its incomparable 24-hour learning environment. Great teaching, great students, community and tradition - these are the hallmarks of the Queen's experience. The University was established by Royal Charter of Queen Victoria in 1841 - twenty-six years before Canadian confederation. Classes were first held in 1842. The earliest degree-granting institution in the united Province of Canada, and the first to establish a student government, Queen's has reflected and helped shape Canadian values and policies, educating many of the country's most notable political and cultural figures