scholarly journals Angularly Resolved Deep Brain Fluorescence Imaging Using a Single Optical Fiber

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Israel J. De La Rosa ◽  
Mehdi Azimipour ◽  
Patrick K. Cullen ◽  
Fred J. Helmstetter ◽  
Ramin Pashaie
Keyword(s):  
Optical Fiber ◽  
Pulse Compression ◽  
Fluorescence Probe ◽  
Signal To Noise Ratio ◽  
Fluorescence Emission ◽  
Compression Technique ◽  
Excitation Light ◽  
New Device ◽  
Deep Brain

In this article, we report the development of a minimally invasive fiber optic based fluorescence probe which can reach deep brain objects and measure the intensity and spatial distribution of fluorescence signals in the tissue. In this design, the brain is scanned by a single penetrating side-firing optical fiber which delivers excitation light pulses to the tissue at different depths and orientations and simultaneously collects samples of fluorescence emission signals. Signal-to-noise ratio of the measurements is improved by adapting the pulse compression technique and the theory of optimal filters. Effects of each design parameter on the overall performance of the scanner, including the spatial resolution and speed of scanning, are analyzed and experimentally measured. In vivo experiments show that the new device, despite the simplicity of the design, provides valuable information particularly useful in optogenetic stimulation experiments where the exact position of the fiber tip and the radiation orientation can change the outcome of a test.

Methods for enhancement of high-sensitivity detection for a surface wave EMAT

2021 ◽  
pp. 1-23
Author(s):  
Jin Zhang ◽  
Xin Wang ◽  
Xuebing Wang ◽  
LingLing Zheng ◽  
Ruipeng Li ◽  
...  
Keyword(s):  
Conversion Efficiency ◽  
Pulse Compression ◽  
Signal To Noise Ratio ◽  
Single Layer ◽  
High Sensitivity ◽  
Element Model ◽  
Industrial Applications ◽  
Detection Sensitivity ◽  
Electromagnetic Acoustic Transducer ◽  
Compression Technique

Due to the poor conversion efficiency and signal-to-noise ratio (SNR) of Electromagnetic Acoustic Transducer (EMAT) testing, the defect detection sensitivity is limited, which restricts the extensive industrial applications. A finite element model for the testing process of a meander-coil EMAT was established that considers the simplified excitation and detection circuits for the EMAT. Based on this model, the effect of the connection methods (parallel or series) of the coils in the generating and receiving EMATs on their generating and receiving efficiency was investigated, and the simulation results were validated experimentally. Subsequently, the pulse compression technique with a 13-bit Barker code was used for the EMAT detection, and improvements of the SNR and range resolution were established through numerical simulation and experimental measurement. The results show that compared with the traditional EMAT design, which comprises single-layer transmitting and receiving coils, the conversion efficiency of the optimized EMAT with two excitation and receiving coils in the parallel connection can be improved by 52.8%. With the application of the Barker-coded pulse compression to detect the ultrasonic A-scan signal with no synchronous average, the SNR of the defect echo can be improved by 9.5 dB compared with the A-scan signal with 128 synchronous averages.

scholarly journals Improved Excitation Light Rejection Enhances Small-Animal Fluorescent Optical Imaging

2005 ◽  
Vol 4 (3) ◽  
pp. 153535002005051 ◽  
Author(s):  
Kildong Hwang ◽  
Jessica P. Houston ◽  
John C. Rasmussen ◽  
Amit Joshi ◽  
Shi Ke ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Small Animal ◽  
Large Component ◽  
Signal Ratio ◽  
Excitation Light ◽  
Animal Imaging ◽  
Collimating Optics ◽  
Phantom Studies ◽  
Accurate Imaging

Small-animal fluorescence-enhanced imaging involves the detection of weak fluorescent signals emanating from nanomolar to picomolar concentrations of exogenous or endogenously produced fluorophore concurrent with the rejection of an overwhelmingly large component of backscattered excitation light. The elimination of the back-reflected excitation light of the collected signal remains a major and often unrecognized challenge for further reducing the noise floor and increasing sensitivity of small-animal fluorescence imaging. Herein, we show that the combination of three-cavity interference and holographic super notch filters with appropriate imaging lenses to collimate light improves rejection of excitation light, enabling more accurate imaging. To assess excitation leakage, the “out-of-band ( S(Λ x))” to “in-band ( S(Λ m)– S(Λ x))” signal ratio from phantom studies and the target-to-background ratio (TBR) from in vivo animal imaging was acquired with and without collimating optics. The addition of collimating optics resulted in a 51% to 75% reduction in the ratio of ( S(Λ x))/( S(Λ m)– S(Λ x)) for the phantom studies and an improvement of TBR from 11% to 31% and of signal-to-noise ratio from 11% to 142% for an integrin-targeting conjugate in human glioma xenografts.

High S/N Ratio Guided Wave Inspection of Pipe Using Chirp Pulse Compression

2004 ◽  
Author(s):  
Kiyokazu Toiyama ◽  
Takahiro Tsutsumoto ◽  
Takashi Ikeda ◽  
Takahiro Hayashi
Keyword(s):  
Long Range ◽  
Pulse Compression ◽  
Signal To Noise Ratio ◽  
Effective Means ◽  
Side Lobe ◽  
Guided Wave ◽  
Pulse Excitation ◽  
Chirp Pulse ◽  
Compression Technique ◽  
Heat Insulator

Guided wave is expected as the most promising technique for rapid long-range inspection of pipes. However, signal to noise ratio is still required to be improved, especially in highly attenuative pipes covered with heat insulator and/or buried in the ground. Recently, pulse compression technique has been developed as an effective means for improving S/N ratio in the field of radar detection. In this paper, chirp pulse compression technique was applied to the long-range inspection of pipe using guided wave. The technical brief explanation about chirp pulse compression was described. Example data signals of burst wave excitation way and chirp pulse excitation way with commonly -used amplifier were reviewed with respect to unwanted side lobe. The cause of a side lobe was investigated, and the amplifier with excellent distortion property was presented to improve S/N ratio of system with quite vanishing of side lobe.

Fluorescence Turn-On Detection of Ascorbic Acid Using a Self-Assembled Lanthanide Polymer Nanoparticle

2019 ◽  
Vol 74 (3) ◽  
pp. 275-284
Author(s):  
Hui-Hui Zeng ◽  
Fang Liu ◽  
Long-Ke Hu ◽  
Jie Deng ◽  
Yue-Ping Xie ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Coordination Polymer ◽  
Fluorescence Probe ◽  
Signal To Noise Ratio ◽  
Polymer Nanoparticles ◽  
Sensing Systems ◽  
Sensing Platforms ◽  
Lanthanide Coordination Polymer ◽  
Fluorescence Turn On

Ascorbic acid (AA), or vitamin C, is an important reactive biological molecule in vivo, and an abnormal level of AA is associated with many diseases. Therefore, the rapid, sensitive, and selective detection of AA levels is of significance in cases of medical assay and diagnosis. Compared with other nanoparticles, lanthanide coordination polymer nanoparticles (Ln-CPs) have been demonstrated as the excellent biomolecule sensing platforms due to their unique optical properties and intrinsic porosities. In this work, the cerium coordination polymer nanoparticles ATP-Ce-Tris were synthesized in a simple and quick way. The synthesized ATP-Ce-Tris nanoparticle shows the characteristic peak of Ce3+ located at 365 nm, which is corresponding to the 4f→5d transition of Ce3+. In the presence of Fe3+, the fluorescence of ATP-Ce-Tris quenched, and the following added ascorbic acid (AA) makes it restoring effectively. Based on this, we constructed a fluorescence probe with excellent sensitivity for AA sensing in a wide linear relationship from 0.05 to 500 μM. The detection limit was as low as 18 nM (signal-to-noise ratio of three), which is one or two orders of magnitude lower than those of reported sensors. The proposed sensing systems also exhibits excellent sensitivity for AA detection in human serum sample, exploiting a valuable platform for AA analysis in clinic diagnostic and drug screening.

scholarly journals Miniaturized Devices for Bioluminescence Imaging in Freely Behaving Animals

2020 ◽  
Author(s):  
Dmitrijs Celinskis ◽  
Nina Friedman ◽  
Mikhail Koksharov ◽  
Jeremy Murphy ◽  
Manuel Gomez-Ramirez ◽  
...  
Keyword(s):  
Time Course ◽  
Signal To Noise Ratio ◽  
Major Advance ◽  
Signal To Noise ◽  
Excitation Light ◽  
Calcium Indicators ◽  
Freely Behaving ◽  
Open Question

AbstractFluorescence miniature microscopy in vivo has recently proven a major advance, enabling cellular imaging in freely behaving animals. However, fluorescence imaging suffers from autofluorescence, phototoxicity, photobleaching and non-homogeneous illumination artifacts. These factors limit the quality and time course of data collection. Bioluminescence provides an alternative kind of activity-dependent light indicator. Bioluminescent calcium indicators do not require light input, instead generating photons through chemiluminescence. As such, limitations inherent to the requirement for light presentation are eliminated. Further, bioluminescent indicators also do not require excitation light optics: the removal of this component should make lighter and lower cost microscope with fewer assembly parts. While there has been significant recent progress in making brighter and faster bioluminescence indicators, parallel advances in imaging hardware have not yet been realized. A hardware challenge is that despite potentially higher signal-to-noise of bioluminescence, the signal strength is lower than that of fluorescence. An open question we address in this report is whether fluorescent miniature microscopes can be rendered sensitive enough to detect bioluminescence. We demonstrate this possibility in vitro and in vivo by implementing optimizations of the UCLA fluorescent miniscope. These optimizations yielded a miniscope (BLmini) which is 22% lighter in weight, has 45% fewer components, is up to 58% less expensive, offers up to 15 times stronger signal (as dichroic filtering is not required) and is sensitive enough to capture spatiotemporal dynamics of bioluminescence in the brain with a signal-to-noise ratio of 34 dB.

Isolierung von PS II-Partikeln mit in vivo Eigenschaften aus Euglena gracilis, Stamm Z / Isolation of PS II-Particels with in vivo Characteristics from Euglena gracilis, Stamm Z

1982 ◽  
Vol 37 (3-4) ◽  
pp. 256-259 ◽  
Author(s):  
F. Schuler ◽  
P. Brandt ◽  
W. Wießner
Keyword(s):  
Euglena Gracilis ◽  
Fluorescence Emission ◽  
Improved Method ◽  
Ps Ii ◽  
Ps I ◽  
Emission And Absorption Spectra ◽  
Chlorophyll Protein ◽  
Ps Ii Activity ◽  
Photosystem Ii Particles

Abstract An improved method for isolation of (photosystem II)-particles from Euglena gracilis, strain Z was established. PS II-particles isolated by ultrasonic treatment and following differential centrifugation show fluorescence emission and absorption spectra identical with in vivo properties of Euglena gracilis. These PS II-particles have only PS II-activity and contain CP a, the typical chlorophyll-protein-complex of PS II. No contamination of PS I-components are detectable.

In Vivo Deep-Brain Structural and Hemodynamic Multiphoton Microscopy Enabled by Quantum Dots

Nano Letters ◽  
2019 ◽  
Vol 19 (8) ◽  
pp. 5260-5265 ◽  
Author(s):  
Hongji Liu ◽  
Xiangquan Deng ◽  
Shen Tong ◽  
Chen He ◽  
Hui Cheng ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Multiphoton Microscopy ◽  
Deep Brain

scholarly journals Key Distribution Scheme for Optical Fiber Channel Based on SNR Feature Measurement

Photonics ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 208
Author(s):  
Xiangqing Wang ◽  
Jie Zhang ◽  
Bo Wang ◽  
Kongni Zhu ◽  
Haokun Song ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Optical Networks ◽  
Signal To Noise Ratio ◽  
Key Distribution ◽  
Key Generation ◽  
Sensitive Data ◽  
Big Data Applications ◽  
Distribution Scheme ◽  
Fiber Channel ◽  
Physical Level

With the increase in the popularity of cloud computing and big data applications, the amount of sensitive data transmitted through optical networks has increased dramatically. Furthermore, optical transmission systems face various security risks at the physical level. We propose a novel key distribution scheme based on signal-to-noise ratio (SNR) measurements to extract the fingerprint of the fiber channel and improve the physical level of security. The SNR varies with time because the fiber channel is affected by many physical characteristics, such as dispersion, polarization, scattering, and amplifier noise. The extracted SNR of the optical fiber channel can be used as the basis of key generation. Alice and Bob can obtain channel characteristics by measuring the SNR of the optical fiber channel and generate the consistent key by quantization coding. The security and consistency of the key are guaranteed by the randomness and reciprocity of the channel. The simulation results show that the key generation rate (KGR) can reach 25 kbps, the key consistency rate (KCR) can reach 98% after key post-processing, and the error probability of Eve’s key is ~50%. In the proposed scheme, the equipment used is simple and compatible with existing optic fiber links.

scholarly journals Silica-Coated Fe3O4 Nanoparticles as a Bifunctional Agent for Magnetic Resonance Imaging and ZnII Fluorescent Sensing

2021 ◽  
Vol 20 ◽  
pp. 153303382110365
Author(s):  
Lin Qiu ◽  
Shuwen Zhou ◽  
Ying Li ◽  
Wen Rui ◽  
Pengfei Cui ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Contrast Agent ◽  
Quantum Interference ◽  
Inductively Coupled Plasma ◽  
Fluorescence Emission ◽  
Mri Contrast Agent ◽  
Core Shell ◽  
Resonance Imaging

Bifunctional magnetic/fluorescent core-shell silica nanospheres (MNPs) encapsulated with the magnetic Fe3O4 core and a derivate of 8-amimoquinoline (N-(quinolin-8-yl)-2-(3-(triethoxysilyl) propylamino) acetamide) (QTEPA) into the shell were synthesized. These functional MNPs were prepared with a modified stöber method and the formed Fe3O4@SiO2-QTEPA core-shell nanocomposites are biocompatible, water-dispersible, and stable. These prepared nanoparticles were characterized by X-ray power diffraction (XRD), transmission electron microscopy (TEM), thermoelectric plasma Quad II inductively coupled plasma mass spectrometry (ICP-MS), superconducting quantum interference device (SQUID), TG/DTA thermal analyzer (TGA) and Fourier transform infrared spectroscopy (FTIR). Further application of the nanoparticles in detecting Zn2+ was confirmed by the fluorescence experiment: the nanosensor shows high selectivity and sensitivity to Zn2+ with a 22-fold fluorescence emission enhancement in the presence of 10 μM Zn2+. Moreover, the transverse relaxivity measurements show that the core-shell MNPs have T2 relaxivity (r2) of 155.05 mM−1 S−1 based on Fe concentration on the 3.0 T scanner, suggesting that the compound can be used as a negative contrast agent for MRI. Further in vivo experiments showed that these MNPs could be used as MRI contrast agent. Therefore, the new nanosensor provides the dual modality of magnetic resonance imaging and optical imaging.

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