High Signal-to-Noise Ratio and High Resolution Detection Techniques for Photopyroelectric Thermal Wave Imaging Reconstruction

1994 ◽  
Vol 33 (Part 1, No. 5B) ◽  
pp. 3255-3259 ◽  
Author(s):  
Atsushi Yarai ◽  
Kazuo Sakamoto ◽  
Takuji Nakanishi
Keyword(s):  
High Resolution ◽  
Thermal Wave ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
Signal To Noise ◽  
Detection Techniques ◽  
Imaging Reconstruction ◽  
Wave Imaging ◽  
Noise Ratio ◽  
Thermal Wave Imaging

scholarly journals Seismology of southern Be stars

1994 ◽  
Vol 162 ◽  
pp. 104-105
Author(s):  
Eduardo Janot-Pacheco ◽  
Nelson Vani Leister
Keyword(s):  
High Resolution ◽  
Signal To Noise Ratio ◽  
Ccd Camera ◽  
High Signal ◽  
Be Stars ◽  
Signal To Noise ◽  
Photometric Variability ◽  
Spectroscopic Observations ◽  
Photometric Observations ◽  
Noise Ratio

We have started in 1990 a search for moving bumps in the HeI λ 667.8 nm of mainly southern, bright Be stars. The objects of our sample have been selected on the basis of photometric variability (Cuypers et al., 1989). High resolution (R≥ 30,000), high signal-to-noise ratio (S/R≥ 300) spectroscopic observations have been performed at the brazilian Laboratório Nacional de Astrofísica with a CCD camera attached to the coudé spectrograph of the 1.60 m telescope (e.g. Table I). Several hundred spectra have been taken during the last three years. Photometric observations simultaneous with spectroscopy were made on the same site in July 1992 with a two-channel photometer (Stromgren b filter) and a CCD camera (Johnson B filter) installed at two 0.60 m telescopes. The idea is try to disentangle the controversy between NRP and RM models with the help of simultaneous spectroscopy and photometry.

scholarly journals 12C/13C Ratios and Li Abundances in Low-Mass C Stars

2000 ◽  
Vol 177 ◽  
pp. 89-95
Author(s):  
Carlos Abia ◽  
Jordi Isern
Keyword(s):  
High Resolution ◽  
Carbon Isotope ◽  
Signal To Noise Ratio ◽  
Isotope Ratios ◽  
High Signal ◽  
Isotopic Ratios ◽  
Signal To Noise ◽  
Carbon Isotope Ratios ◽  
Low Mass ◽  
Noise Ratio

High-resolution and high signal-to-noise-ratio spectroscopy is used to derive 12C/13C ratios from the Red System of the CN molecule at 8000 Å in several galactic low-mass C stars previously analyzed for lithium. It is found that Li-rich C stars usually have low isotopic ratios (< 15). This suggests that the Li and 13C enrichments in C stars might be produced by a similar mechanism. However, due to the large uncertainties in the abundance derivations for both Li and carbon isotope ratios, this result must be confirmed with further studies.

Narrow-frequency sharp-angular filters using all-dielectric cascaded meta-gratings

Nanophotonics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 3443-3450 ◽  
Author(s):  
Wei-Nan Liu ◽  
Rui Chen ◽  
Wei-Yi Shi ◽  
Ke-Bo Zeng ◽  
Fu-Li Zhao ◽  
...  
Keyword(s):  
Thin Film ◽  
Signal To Noise Ratio ◽  
Incident Angle ◽  
Design Strategy ◽  
Transmission Peak ◽  
High Signal ◽  
Waveguide Array ◽  
Signal To Noise ◽  
Center Wavelength ◽  
Noise Ratio

AbstractSelective transmission or filtering always responds to either frequency or incident angle, so as hardly to maximize signal-to-noise ratio in communication, detection and sensing. Here, we propose compact meta-filters of narrow-frequency sharp-angular transmission peak along with broad omnidirectional reflection sidebands, in all-dielectric cascaded subwavelength meta-gratings. The inherent collective resonance of waveguide-array modes and thin film approximation of meta-grating are employed as the design strategy. A unity transmission peak, locating at the incident angle of 44.4° and the center wavelength of 1550 nm, is demonstrated in a silicon meta-filter consisting of two-layer silicon rectangular meta-grating. These findings provide possibilities in cascaded meta-gratings spectroscopic design and alternative utilities for high signal-to-noise ratio applications in focus-free spatial filtering and anti-noise systems in telecommunications.

scholarly journals Low-dose, phase-contrast mammography with high signal-to-noise ratio

2016 ◽  
Vol 7 (2) ◽  
pp. 381 ◽  
Author(s):  
Lukas B. Gromann ◽  
Dirk Bequé ◽  
Kai Scherer ◽  
Konstantin Willer ◽  
Lorenz Birnbacher ◽  
...  
Keyword(s):  
Phase Contrast ◽  
Low Dose ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
Signal To Noise ◽  
Noise Ratio
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