High performance wavelength-swept laser with mode-locking technique for optical coherence tomography

2009 ◽  
Vol 282 (1) ◽  
pp. 88-92 ◽  
Author(s):  
Youxin Mao ◽  
Costel Flueraru ◽  
Sherif Sherif ◽  
Shoude Chang
Keyword(s):  
Optical Coherence Tomography ◽  
High Performance ◽  
Mode Locking ◽  
Optical Coherence

scholarly journals Phase stable swept-source optical coherence tomography with active mode-locking laser for contrast enhancements of retinal angiography

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kwan Seob Park ◽  
Eunwoo Park ◽  
Hwidon Lee ◽  
Hyun-Ji Lee ◽  
Sang-Won Lee ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Phase Stability ◽  
Averaging Method ◽  
Mode Locking ◽  
Optical Coherence ◽  
Swept Source ◽  
Active Mode ◽  
Coherent Averaging ◽  
Noise Ratio ◽  
High Phase

AbstractSwept-source optical coherence tomography (SS-OCT) is an attractive high-speed imaging technique for retinal angiography. However, conventional swept lasers vary the cavity length of the laser mechanically to tune the output wavelength. This causes sweep-timing jitter and hence low phase stability in OCT angiography. Here, we improve an earlier phase-stabilized, akinetic, SS-OCT angiography (OCTA) method by introducing coherent averaging. We develop an active mode-locking (AML) laser as a high phase-stable akinetic swept source for the OCTA system. The phase stability of the improved system was analyzed, and the effects of coherent averaging were validated using a retina phantom. The effectiveness of the coherent averaging method was further confirmed by comparing coherently and conventionally averaged en face images of human retinal vasculature for their contrast-to-noise ratio, signal-to-noise ratio, and vasculature connectivity. The contrast-to-noise ratio was approximately 1.3 times larger when applying the coherent averaging method in the human retinal experiment. Our coherent averaging method with the high phase-stability AML laser source for OCTA provides a valuable tool for studying healthy and diseased retinas.

scholarly journals Capillary stall quantification from optical coherence tomography angiogram maximum intensity projections

2021 ◽  
Author(s):  
Signe Kirk Fruekilde ◽  
Eugenio Gutiérrez Jiménez ◽  
Kim Ryun Drasbek ◽  
Christopher J Bailey
Keyword(s):  
Blood Flow ◽  
Optical Coherence Tomography ◽  
High Performance ◽  
Large Data ◽  
Maximum Intensity ◽  
Reproducible Research ◽  
Optical Coherence ◽  
Laptop Computer ◽  
Maximum Intensity Projections

Optical coherence tomography (OCT) is applicable to the study of cerebral microvasculature in vivo. Optimised acquisition schemes enable the generation of three-dimensional OCT angiograms, i.e., volumetric images of red blood cell flux in capillary networks, currently at a repetition rate of up to 1/10 seconds. This makes testable a new class of hypotheses that strive to bridge the gap between microscopic phenomena occurring at the spatial scale of neurons, and less invasive but crude techniques to measure macroscopic blood flow dynamics. Here we present a method for quantifying the occurrence of transient capillary stalls in OCT angiograms, i.e., events during which blood flow through a capillary branch is temporarily occluded. By making the assumption that information on such events is present predominantly in the imaging plane, we implemented a pipeline that automatically segments a network of interconnected capillaries from the maximum intensity projections (MIP) of a series of 3D angiograms. We then developed tools enabling rapid manual assessment of the binary flow status (open/stalled) of hundreds of capillary segments based on the intensity profile of each segment across time. The entire pipeline is optimized to run on a standard laptop computer, requiring no high-performance, low-availability resources, despite very large data volumes. To further reduce the threshold of adoption, and ultimately to support the development of reproducible research methods in the young field, we provide the documented code for scrutiny and re-use under a permissive open-source license.

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