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Coffee certification criterion using the photoacoustic technique
Microelectronics Journal, 2008The photoacoustic (PA) technique allows a spectroscopic analysis of organic opaque samples and its thermal characterization; so this technique gives information about the pigmentation and the roasting modelling parameters, important for industry and commercialization process, when it is applied to green and powdered coffee samples, respectively.
Fernando Gordillo Delgado +2 more
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Photoacoustic imaging using the Hadamard transform technique
Applied Optics, 1982The principles of Hadamard transformation are applied to photoacoustic imaging. The advantages are twofold: reduction of the power density at the sample, and improvement of SNR due to multiplexing advantage. The compatibility of Hadamard with other multiplex transform techniques is discussed.
H, Coufal, U, Moller, S, Schneider
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Photoacoustic imaging using a Fourier transform technique
Applied Optics, 1982The principles of Fourier transformation are applied to photoacoustic imaging. Advantages are threefold: reduction of the power density at the sample; improvement of signal to noise ratio due to multiplexing advantage; and increase of spatial resolution by additional measurements with masks corresponding to higher overtones.
H, Coufal, U, Moller, S, Schneider
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Photoacoustic spectroscopy technique in stress analysis
Measurement, 1984Abstract The use of photoacoustic signal in stress analysis has been demonstrated. The results obtained were encouraging. Two main constraints which appear in using conventional photoelastic techniques, namely transparency and double-refracting effect, have been removed through the use of photoacoustic.
S.S. Issa, M.E. Abu-Zeid
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Moire displacement detection by the photoacoustic technique
SPIE Proceedings, 1991Moire effect produced by the two gratings under coherent illumination attracts a high level of interest in the mask and wafer alignment for X-ray lithographic system. In such reflection optical arrangement, the displacement signal is often affected by the light reflected directly from the mask grating.
Kazuhiro Hane, S. Watanabe, Toshio Goto
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Photoacoustic microscopy with a new modulation technique
Applied Physics Letters, 1981A new type of photoacoustic microscopy is described in which the beam position, rather than the beam intensity, is modulated. It is demonstrated experimentally that the new technique provides greater detail and contrast than conventional photoacoustic microscopy.
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Photoacoustic spectroscopy: a measurement technique for low absorption coefficients
Applied Optics, 1977The case in which a laser beam modulated at angular frequency omega passes through the weakly absorbing windows of a gas cell which contains a nonabsorbing gas is investigated in this paper. In particular, the frequency dependences of the acoustic stresses in the gas which arise from the surface and bulk absorption are derived. An intermediate range of
H S, Bennett, R A, Forman
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Minority species concentration measurements in flames by the photoacoustic technique
Applied Optics, 1982The potential of the photoacoustic technique to detect minority species concentrations in combustion environments has been investigated. In particular, we have detected very low concentrations of NO(2) molecules produced in the combustion of methane, oxygen, and nitrogen in a flat-flame burner.
K, Tennal, G J, Salamo, R, Gupta
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Thermal diffusivity of NTC layers obtained with photoacoustic technique
Microelectronics International, 2004The thermal diffusivity of thick film NTC layers based on a metal oxide powder mixture was measured at room temperature by the photoacoustic (PA) technique. The powder mixture was composed of MnO (60 percent), CoO (32 percent) and Fe2O3 (8 percent), which were ball milled to nanometer particle size.
Aleksić, Obrad A. +5 more
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Pulse photoacoustic technique for the study of vibrational relaxation in gases
Applied Optics, 1995Characteristic peculiarities of the formation of the photoacoustic-detector signal from excitation of absorbing gas molecules by a short laser pulse (τ(p) « τ(vt)) that allows for the natural oscillations of the microphone membrane are considered. A technique for τ(vt) measurement is proposed on the strength of the finding that the signal form is ...
V A, Kapitanov, B A, Tikhomirov
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