scholarly journals Numerical Modelling of a Distributed Acoustic Sensor Based on Ultra-Low Loss-Enhanced Backscattering Fibers

Sensors ◽  
2021 ◽  
Vol 21 (20) ◽  
pp. 6869
Author(s):  
Lieke Dorine van van Putten ◽  
Ali Masoudi ◽  
James Snook ◽  
Gilberto Brambilla
Keyword(s):  
Numerical Modelling ◽  
Signal To Noise Ratio ◽  
Single Mode ◽  
Acoustic Sensor ◽  
Low Loss ◽  
Signal To Noise ◽  
Optical Components ◽  
Enhanced Backscattering ◽  
Noise Ratio

In this study, a distributed acoustic sensor (DAS) was numerically modeled based on the non-ideal optical components with their noises and imperfections. This model is used to compare the response of DAS systems to standard single-mode fibers and ultra-low loss-enhanced backscattering (ULEB) fibers, a fiber with an array of high reflective points equally spaced along its length. It is shown that using ULEB fibers with highly reflective points improves the signal-to-noise ratio and linearity of the measurement, compared with the measurement based on standard single-mode fibers.

Signal to Noise Ratio in Stem and Low-Loss Images

1980 ◽  
Vol 38 ◽  
pp. 236-237
Author(s):  
A. N. Broers
Keyword(s):  
Signal To Noise Ratio ◽  
High Contrast ◽  
Low Loss ◽  
Signal To Noise ◽  
High Quality ◽  
High Brightness ◽  
Electron Sources ◽  
Noise Ratio

The number of pixels or resolution elements in STEM images has frequently been relatively low (< 105) and in many images only a few gray levels can be distinguished. This is surprising considering the high brightness of the electron sources used in most cases, and the high contrast typically present in STEM images. While it is technologically expensive to match the several million resolution elements resolved in high quality TEM images, it is shown here that it is relatively straightforward to produce STEM images containing at least a million resolution elements.

A double-pass Sisam spectrometer for the near infrared

1975 ◽  
Vol 346 (1646) ◽  
pp. 395-412 ◽  
Keyword(s):  
Spectral Range ◽  
Near Infrared ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Double Pass ◽  
Optical Components ◽  
Common Axis ◽  
Noise Ratio ◽  
Real Gain

A double-pass Sisam spectrometer of simplified design is described in which the two gratings rotate about a common axis. Sample spectra are given and the performance of the instrument is assessed and compared with that predicted theoretically. A resolution of 0.05 cm -1 has been achieved at 1.6 µm, corresponding to 90% of the maximum theoretically attainable with the gratings and configuration used. This performance was maintained over a continuously scanned spectral range of 500 cm -1 without realignment of the optical components. The instrument thus offers a real gain in signal-to-noise ratio over the equivalent, practical slit spectrometer of a factor of between 30 and 1000.

scholarly journals Normalized differential method for improving the signal-to-noise ratio of a distributed acoustic sensor

2019 ◽  
Vol 58 (18) ◽  
pp. 4933 ◽  
Author(s):  
Islam Ashry ◽  
Yuan Mao ◽  
Mohd Sharizal Alias ◽  
Tien Khee Ng ◽  
Frode Hveding ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Differential Method ◽  
Acoustic Sensor ◽  
Signal To Noise ◽  
Noise Ratio

scholarly journals On Microwave Imaging with Absorbing Metasurface Enclosure

2020 ◽  
Author(s):  
Ziqi Liu ◽  
Nozhan Bayat ◽  
Puyan Mojabi
Keyword(s):  
Boundary Conditions ◽  
Signal To Noise Ratio ◽  
Physical Structure ◽  
Microwave Imaging ◽  
Low Loss ◽  
Signal To Noise ◽  
Impedance Boundary ◽  
Impedance Boundary Conditions ◽  
Angular Dependency ◽  
Noise Ratio

Matching fluids used in microwave imaging are often lossy to reduce the reflections from the system enclosure. To enable the use of low-loss matching fluids, we investigate the use of absorbing metasurfaces as the enclosure. This has the potential to enhance the signal-to-noise ratio of the data, thus, enhancing the achievable image accuracy. The presented example has the following limitation: as opposed to design and simulation of the physical structure of the metasurface enclosure, it uses two impedance boundary conditions on top of a metallic-backed substrate. Thus, the angular dependency of a practical absorber is not completely taken into account by this model. At the conference, we'll also consider a microwave imaging metasurface enclosure via design and simulation of a physical structure.

Improving the signal-to-noise ratio in a fiber-optic Fabry–Pérot acoustic sensor

2019 ◽  
Vol 16 (6) ◽  
pp. 065106 ◽  
Author(s):  
Hamed Moradi ◽  
Fahimeh Hosseinibalam ◽  
Smaeyl Hassanzadeh
Keyword(s):  
Fiber Optic ◽  
Signal To Noise Ratio ◽  
Acoustic Sensor ◽  
Signal To Noise ◽  
Fabry Perot ◽  
Noise Ratio
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