scholarly journals Remote Speckle-Based Measurements of Backward Brillouin Acoustic Vibrations in Optical Fibers

2020 ◽  
Vol 10 (2) ◽  
pp. 664
Author(s):  
Sagie Asraf ◽  
Benjamin Lengenfelder ◽  
Michael Schmidt ◽  
Zeev Zalevsky
Keyword(s):  
Spatial Resolution ◽  
Optical Fibers ◽  
Experimental Results ◽  
Limiting Factors ◽  
Acoustic Vibrations ◽  
Frequency Measurements ◽  
Novel Technique ◽  
Temporal Tracking ◽  
Speckle Patterns ◽  
Pump Waves

We propose a novel technique for measurements of Brillouin acoustic vibrations based on temporal tracking of back-reflected speckle patterns. The proposed method holds the potential to enhance some of the limiting factors in Brillouin frequency measurements while yielding increased spatial resolution and shorter scanning times of the inspected fiber. Experimental results show the capabilities of the proposed method are presented, using a two pump-waves configuration.

scholarly journals Multiple Light Coupling and Routing via a Microspherical Resonator Integrated in a T-Shaped Optical Fiber Configuration System

Micromachines ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 521 ◽  
Author(s):  
Georgia Konstantinou ◽  
Karolina Milenko ◽  
Kyriaki Kosma ◽  
Stavros Pissadakis
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
Single Mode ◽  
Equatorial Region ◽  
Experimental Results ◽  
Glass Microsphere ◽  
Single Mode Optical Fiber ◽  
Light Coupling ◽  
Fiber Taper ◽  
Optical Fiber Taper

We demonstrate a three-port, light guiding and routing T-shaped configuration based on the combination of whispering gallery modes (WGMs) and micro-structured optical fibers (MOFs). This system includes a single mode optical fiber taper (SOFT), a slightly tapered MOF and a BaTiO3 microsphere for efficient light coupling and routing between these two optical fibers. The BaTiO3 glass microsphere is semi-immersed into one of the hollow capillaries of the MOF taper, while the single mode optical fiber taper is placed perpendicularly to the latter and in contact with the equatorial region of the microsphere. Experimental results are presented for different excitation and reading conditions through the WGM microspherical resonator, namely, through single mode optical fiber taper or the MOF. The experimental results indicate that light coupling between the MOF and the single mode optical fiber taper is facilitated at specific wavelengths, supported by the light localization characteristics of the BaTiO3 glass microsphere, with spectral Q-factors varying between 4.5 × 103 and 6.1 × 103, depending on the port and parity excitation.

scholarly journals Hyperspectral Pansharpening Based on Homomorphic Filtering and Weighted Tensor Matrix

2019 ◽  
Vol 11 (9) ◽  
pp. 1005
Author(s):  
Jiahui Qu ◽  
Yunsong Li ◽  
Qian Du ◽  
Wenqian Dong ◽  
Bobo Xi
Keyword(s):  
Spatial Resolution ◽  
Spatial Information ◽  
Mean Squared Error ◽  
High Spatial Resolution ◽  
Experimental Results ◽  
Spectral Information ◽  
Morphological Operation ◽  
Effective Technique ◽  
Squared Error ◽  
Homomorphic Filtering

Hyperspectral pansharpening is an effective technique to obtain a high spatial resolution hyperspectral (HS) image. In this paper, a new hyperspectral pansharpening algorithm based on homomorphic filtering and weighted tensor matrix (HFWT) is proposed. In the proposed HFWT method, open-closing morphological operation is utilized to remove the noise of the HS image, and homomorphic filtering is introduced to extract the spatial details of each band in the denoised HS image. More importantly, a weighted root mean squared error-based method is proposed to obtain the total spatial information of the HS image, and an optimized weighted tensor matrix based strategy is presented to integrate spatial information of the HS image with spatial information of the panchromatic (PAN) image. With the appropriate integrated spatial details injection, the fused HS image is generated by constructing the suitable gain matrix. Experimental results over both simulated and real datasets demonstrate that the proposed HFWT method effectively generates the fused HS image with high spatial resolution while maintaining the spectral information of the original low spatial resolution HS image.

Distributed Brillouin Sensing With Centimeter-Order Spatial Resolution in Polymer Optical Fibers

2014 ◽  
Vol 32 (21) ◽  
pp. 3999-4003 ◽  
Author(s):  
Neisei Hayashi ◽  
Yosuke Mizuno ◽  
Kentaro Nakamura
Keyword(s):  
Spatial Resolution ◽  
Optical Fibers ◽  
Polymer Optical Fibers

A Concave Annular Array Design, Based on Phasor Summation — Part II: Beam Profiles and Resultant Images by B-Scan and Synthetic Focus Methods

1988 ◽  
Vol 10 (4) ◽  
pp. 287-297
Author(s):  
Weiquan Yuan ◽  
Steven A. Johnson ◽  
Michael J. Berggren ◽  
Richard S. Eidens
Keyword(s):  
Spatial Resolution ◽  
Experimental Results ◽  
Frequency Range ◽  
Theoretical Limit ◽  
Array Design ◽  
Annular Array ◽  
Thin Thread ◽  
Reflection Image ◽  
Aperture Arrays

A brief review of the synthetic focusing method is given. The theoretical limit of resolution that may be achieved with the synthetic focusing methods is demonstrated using experimental results on a thin thread obtained with an annular array whose design was given in Part I. The advantage of large aperture arrays is illustrated by an in vitro reflection image of a dog artery, made with this array, that has at least four times the spatial resolution of present clinical B-scanners operating in the same frequency range.

Distributed Fiber Optic Strain Sensing with Embedded Small-Diameter Optical Fibers in CFRP Laminate

2007 ◽  
Vol 334-335 ◽  
pp. 1013-1016
Author(s):  
Tadahito Mizutani ◽  
Takafumi Nishi ◽  
Nobuo Takeda
Keyword(s):  
Spatial Resolution ◽  
Optical Fibers ◽  
Composite Structures ◽  
Fiber Optic ◽  
Current Trend ◽  
Small Diameter ◽  
Long Distance ◽  
Distributed Sensors ◽  
Cfrp Laminate ◽  
Sensing Applications

Although demand for composite structures rapidly increase due to the advantages in weight, there are few effective assessment techniques to enable the quality control and guarantee the durability. In particular, an invisible microscopic damage detection technology is highly required because damages such as transverse cracks, debondings, or delaminations can lead to the critical failure of the structures. Among many non-destructive evaluation (NDE) methods for composite structures, fiber optic sensors are especially attractive due to the high sensitivity, the lightweight, and the small size. In the current trend of the structural health monitoring technology, fiber Bragg gratings (FBG) sensors are frequently used as strain or temperature sensors, and Brillouin scattering sensors are also often used for a long distance distributed measurement. The Brillouin distributed sensors can measure strain over a distance of 10km while a spatial resolution was limited to 1m. Some novel sensing method is proposed to improve the spatial resolution. The pulse-prepump Brillouin optical time domain analysis (PPP-BOTDA) is one of the latest distributed sensing applications with a cm-order high spatial resolution. The PPP-BOTDA commercial product has the spatial resolution of 10cm, and can measure the strain with a precision of ±25og. This precision, however, can be achieved by using conventional single-mode optical fibers. In our research, small-diameter optical fibers with a cladding diameter of 40om were embedded in the CFRP laminate to avoid the deterioration of the CFRP mechanical properties. Thus, in order to verify the performance of PPP-BOTDA, the distributed strain measurement was conducted with the small-diameter optical fibers embedded in the CFRP laminate.

Textural Variations in B-Mode Ultrasonography: A Stochastic Model

1981 ◽  
Vol 3 (3) ◽  
pp. 235-257 ◽  
Author(s):  
Stephen W. Flax ◽  
Gary H. Glover ◽  
Norbert J. Pelc
Keyword(s):  
Stochastic Model ◽  
Clinical Diagnosis ◽  
Spatial Resolution ◽  
Imaging System ◽  
Experimental Results ◽  
Texture Formation ◽  
Tissue Microstructure ◽  
Analytic Models ◽  
Insight Into

Analysis of textural patterns in gray-scale ultrasonography is frequently the basis for clinical diagnosis. It has been found, however, that texture is shaped not only by tissue microstructure but by characteristics of the imaging system as well. This paper describes computer and analytic models which give insight into the role of the imager in texture formation. It is shown that spatial resolution and texture granularity are not simply related, and that axial and lateral texture are determined by unrelated phenomena. Experimental results are given which confirm the modeling.

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