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Wyszukujesz frazę "continuous wave" wg kryterium: Temat


Wyświetlanie 1-4 z 4
Tytuł:
Terahertz photomixer
Autorzy:
Pliński, E.
Powiązania:
https://bibliotekanauki.pl/articles/200658.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
continuous wave optical devices
THz photomixers
terahertz radiation
Opis:
The paper gives a review of continuous wave optical devices called THz photomixers used for excitation and detection of the terahertz radiation. Possible structures of the terahertz photomixers are classified and described.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2010, 58, 4; 463-470
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wigner transform approach to dynamic-variable partially coherent laser beam characterization
Autorzy:
Jabczyński, J.
Gontar, P.
Gorajek, Ł.
Powiązania:
https://bibliotekanauki.pl/articles/202109.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
laser beams
partial coherence
high-power continuous-wave lasers
Wigner transform
aberrations
Opis:
1) Background: the modeling, characterization, transformation and propagation of high-power CW laser beams in optical (including fiberoptic) trains and in the atmosphere have become hot topics in laser science and engineering in the past few years. Single-mode output is mandatory for high-power CW laser applications in the military field. Moreover, an unstationary, dynamic operation regime is typical. Recognized devices and procedures for laser-beam diagnostics could not be directly applied because of dynamic behavior and untypical non-Gaussian profiles. 2) Methods: the Wigner transform approach was proposed to characterize dynamically variable high-power CW laser beams with significant deterministic aberrations. Wavefront-sensing measurements by means of the Shack-Hartmann method and decomposition into an orthogonal Zernike basis were applied. 3) Results: deterministic aberration as a result of unstationary thermal-optic effects depending on the averaged power of the laser output was found. Beam quality determined via the Wigner approach was changed in the same way as the measurements of the beam diameter in the far field. 4) Conclusions: such an aberration component seems to be the main factor causing degradation in beam quality and in brightness of high-power CW laser beams.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2020, 68, 1; 141-146
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Distance measurement errors in silent FM-CW sonar with matched filtering
Autorzy:
Marszal, J.
Salamon, R.
Powiązania:
https://bibliotekanauki.pl/articles/220637.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
silent sonar
frequency modulation
continuous wave
matched filtering
distance measurement
errors
Doppler effect
Opis:
The secretiveness of sonar operation can be achieved by using continuous frequency-modulated sounding signals with reduced power and significantly prolonged repeat time. The application of matched filtration in the sonar receiver provides optimal conditions for detection against the background of white noise and reverberation, and a very good resolution of distance measurements of motionless targets. The article shows that target movement causes large range measurement errors when linear and hyperbolic frequency modulations are used. The formulas for the calculation of these errors are given. It is shown that for signals with linear frequency modulation the range resolution and detection conditions deteriorate. The use of hyperbolic frequency modulation largely eliminates these adverse effects.
Źródło:
Metrology and Measurement Systems; 2012, 19, 2; 321-332
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Applications and Comparison of Continuous Wavelet Transforms on Analysis of A-wave Impulse Noise
Autorzy:
Qin, J.
Sun, P.
Powiązania:
https://bibliotekanauki.pl/articles/177117.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
continuous wavelet transform (CWT)
impulse noise signal processing
time-frequency domain
temporal and spectral resolutions
noise-induced hearing loss
A-wave impulse noise
Opis:
Noise induced hearing loss (NIHL) is a serious occupational related health problem worldwide. The A-wave impulse noise could cause severe hearing loss, and characteristics of such kind of impulse noise in the joint time-frequency (T-F) domain are critical for evaluation of auditory hazard level. This study focuses on the analysis of A-wave impulse noise in the T-F domain using continual wavelet transforms. Three different wavelets, referring to Morlet, Mexican hat, and Meyer wavelets, were investigated and compared based on theoretical analysis and applications to experimental generated A-wave impulse noise signals. The underlying theory of continuous wavelet transform was given and the temporal and spectral resolutions were theoretically analyzed. The main results showed that the Mexican hat wavelet demonstrated significant advantages over the Morlet and Meyer wavelets for the characterization and analysis of the A-wave impulse noise. The results of this study provide useful information for applying wavelet transform on signal processing of the A-wave impulse noise.
Źródło:
Archives of Acoustics; 2015, 40, 4; 503-512
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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