Automated assessment of blood flow in developing embryonic hearts by extending dynamic range of Doppler OCT using a MHz FDML swept laser source (Conference Presentation)

2017 ◽  
Author(s):  
Sahar Elahi ◽  
Lars Thrane ◽  
Andrew M. Rollins ◽  
Michael W. Jenkins
Keyword(s):  
Blood Flow ◽  
Dynamic Range ◽  
Laser Source ◽  
Automated Assessment ◽  
Doppler Oct

scholarly journals Optical whispering-gallery mode barcodes for high-precision and wide-range temperature measurements

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Jie Liao ◽  
Lan Yang
Keyword(s):  
High Precision ◽  
Dynamic Range ◽  
Single Mode ◽  
Whispering Gallery Mode ◽  
Temperature Measurements ◽  
Laser Source ◽  
Multiple Modes ◽  
Whispering Gallery ◽  
Wide Range ◽  
Thermal Sensing

AbstractTemperature is one of the most fundamental physical properties to characterize various physical, chemical, and biological processes. Even a slight change in temperature could have an impact on the status or dynamics of a system. Thus, there is a great need for high-precision and large-dynamic-range temperature measurements. Conventional temperature sensors encounter difficulties in high-precision thermal sensing on the submicron scale. Recently, optical whispering-gallery mode (WGM) sensors have shown promise for many sensing applications, such as thermal sensing, magnetic detection, and biosensing. However, despite their superior sensitivity, the conventional sensing method for WGM resonators relies on tracking the changes in a single mode, which limits the dynamic range constrained by the laser source that has to be fine-tuned in a timely manner to follow the selected mode during the measurement. Moreover, we cannot derive the actual temperature from the spectrum directly but rather derive a relative temperature change. Here, we demonstrate an optical WGM barcode technique involving simultaneous monitoring of the patterns of multiple modes that can provide a direct temperature readout from the spectrum. The measurement relies on the patterns of multiple modes in the WGM spectrum instead of the changes of a particular mode. It can provide us with more information than the single-mode spectrum, such as the precise measurement of actual temperatures. Leveraging the high sensitivity of WGMs and eliminating the need to monitor particular modes, this work lays the foundation for developing a high-performance temperature sensor with not only superior sensitivity but also a broad dynamic range.

The assessment of pathological changes in cerebral blood flow in hypertensive rats with stress-induced intracranial hemorrhage using Doppler OCT: Particularities of arterial and venous alterations/Die Beurteilung von pathologischen Veränderungen der Hirndurchblutung bei hypertensiven Ratten mit Stress-induzierten intrakraniellen Blutungen mittels Doppler-OCT: Besonderheiten von arteriellen und venösen Veränderungen

2013 ◽  
Vol 2 (2) ◽  
Author(s):  
Oxana V. Semyachkina-Glushkovskaya ◽  
Vladislav V. Lychagov ◽  
Olga A. Bibikova ◽  
Igor A. Semyachkin-Glushkovskiy ◽  
Sergey S. Sindeev ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Intracranial Hemorrhage ◽  
Venous Insufficiency ◽  
Hypertensive Rats ◽  
Arterial Tree ◽  
Venous Outflow ◽  
Venous Circulation ◽  
Latent Stage ◽  
Doppler Oct

AbstractHemorrhagic insult is a major source of morbidity and mortality in both adults and newborn babies in the developed countries. The mechanisms underlying the non-traumatic rupture of cerebral vessels are not fully clear, but there is strong evidence that stress, which is associated with an increase in arterial blood pressure, plays a crucial role in the development of acute intracranial hemorrhage (ICH), and alterations in cerebral blood flow (CBF) may contribute to the pathogenesis of ICH. The problem is that there are no effective diagnostic methods that allow for a prognosis of risk to be made for the development of ICH. Therefore, quantitative assessment of CBF may significantly advance the understanding of the nature of ICH. The aim of this study was to determine the particularities of alterations in arterial and venous cerebral circulation in hypertensive rats at different stages of stress-related development of ICH using three-dimensional Doppler optical coherence tomography (DOCT).Experiments were performed in mongrel adult rats. To induce ICH, hypertensive rats underwent stress (effect of severe sound, 120 dB during 2 h). To induce the renal hypertension (two kidneys, one clip) the rats were clipped at the left renal artery with a silver clip. Seven weeks after clipping, the hypertensive rats were used in the experiment. The monitoring of CBF was performed in anesthetized rats with fixed heads using a commercially available swept source OCT system (OCS1300SS; Thorlabs) in the masked period of ICH (4 h after stress) and during ICH (24 h after stress).It could be shown that in stressed rats, compared with non-stressed animals, the latent stage of stress-induced ICH (4 h after stress-off) is characterized by an increase in diameter of the superior sagittal vein with decrease in speed of the blood flow in the venous network, whereas no changes in the CBF in the arterial tree were found in this period. These facts suggest that the masked period of ICH is accompanied by decreasing venous outflow and the development of venous insufficiency. The incidence of ICH, 24 h after stress, is associated with progression of pathological alterations in cerebral venous circulation. All hypertensive rats with ICH demonstrated a greater increase in the diameter of the superior sagittal vein than stressed rats at the latent stage of ICH (in 2.5-fold,In summary, using DOCT we have shown that the latent stage of stress-induced ICH is characterized by a decrease in venous outflow. The incidence of ICH is associated with the progression of pathological alterations in cerebral venous circulation that is accompanied by a decrease in blood flow in the arterial tree. The evaluation of cerebral venous insufficiency is an important diagnostic approach for the prognosis of the risk of developing cerebral hypotension and ICH.

High Dynamic Range Blood Flow RateMeasurement in Large–diameter Vessel

2021 ◽  
Author(s):  
yuan yuan ◽  
Yong Bi ◽  
xiaocao gao ◽  
MinYuan Sun ◽  
weinan gao
Keyword(s):  
Blood Flow ◽  
Dynamic Range ◽  
Large Diameter ◽  
High Dynamic Range ◽  
High Dynamic

scholarly journals Blood flow velocity vector field reconstruction from dual-beam bidirectional Doppler OCT measurements in retinal veins

2015 ◽  
Vol 6 (5) ◽  
pp. 1599 ◽  
Author(s):  
Gerold C. Aschinger ◽  
Leopold Schmetterer ◽  
Veronika Doblhoff-Dier ◽  
Rainer A. Leitgeb ◽  
Gerhard Garhöfer ◽  
...  
Keyword(s):  
Blood Flow ◽  
Vector Field ◽  
Flow Velocity ◽  
Blood Flow Velocity ◽  
Velocity Vector ◽  
Velocity Vector Field ◽  
Field Reconstruction ◽  
Dual Beam ◽  
Doppler Oct

scholarly journals A multi-MHz single-shot data acquisition scheme with high dynamic range: pump–probe X-ray experiments at synchrotrons

2016 ◽  
Vol 23 (6) ◽  
pp. 1409-1423 ◽  
Author(s):  
Alexander Britz ◽  
Tadesse A. Assefa ◽  
Andreas Galler ◽  
Wojciech Gawelda ◽  
Michael Diez ◽  
...  
Keyword(s):  
Data Acquisition ◽  
Dynamic Range ◽  
Avalanche Photodiode ◽  
Fluorescence Yield ◽  
Laser Source ◽  
Single Shot ◽  
Pump Probe ◽  
X Ray ◽  
Acquisition Scheme ◽  
Data Point

The technical implementation of a multi-MHz data acquisition scheme for laser–X-ray pump–probe experiments with pulse limited temporal resolution (100 ps) is presented. Such techniques are very attractive to benefit from the high-repetition rates of X-ray pulses delivered from advanced synchrotron radiation sources. Exploiting a synchronized 3.9 MHz laser excitation source, experiments in 60-bunch mode (7.8 MHz) at beamline P01 of the PETRA III storage ring are performed. Hereby molecular systems in liquid solutions are excited by the pulsed laser source and the total X-ray fluorescence yield (TFY) from the sample is recorded using silicon avalanche photodiode detectors (APDs). The subsequent digitizer card samples the APD signal traces in 0.5 ns steps with 12-bit resolution. These traces are then processed to deliver an integrated value for each recorded single X-ray pulse intensity and sorted into bins according to whether the laser excited the sample or not. For each subgroup the recorded single-shot values are averaged over ∼107 pulses to deliver a mean TFY value with its standard error for each data point,e.g.at a given X-ray probe energy. The sensitivity reaches down to the shot-noise limit, and signal-to-noise ratios approaching 1000 are achievable in only a few seconds collection time per data point. The dynamic range covers 100 photons pulse−1and is only technically limited by the utilized APD.

Mini laser-Doppler (blood) flow monitor with diode laser source and detection integrated in the probe

1984 ◽  
Vol 23 (17) ◽  
pp. 2970 ◽  
Author(s):  
F. F. M. de Mul ◽  
J. van Spijker ◽  
D. van der Plas ◽  
J. Greve ◽  
J. G. Aarnoudse ◽  
...  
Keyword(s):  
Blood Flow ◽  
Diode Laser ◽  
Laser Doppler ◽  
Laser Source
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