Abstract. A photoacoustic cell intended for laser detection of trace gases is represented. The cell is adapted so as to enhance the gas-detection performance and, simultaneously, to reduce the cell size. The cell design provides an efficient cancellation of the window background (a parasite response due to absorption of laser beam in the cell windows) and acoustic isolation from the environment for an acoustic resonance of the cell. The useful photoacoustic response from a detected gas, window background and noise are analyzed in demonstration experiments as functions of the modulation frequency for a prototype cell with the internal volume ∼ 0.5 cm 3 . The minimal detectable absorption for the prototype is estimated to be ∼ 1. The miniaturized spectroscopic hardware of trace-gas analysis is a promising field of application for the photoacoustic technique. The principle of the technique is based on measuring the amplitude and phase for the acoustic pressure oscillation (the so-called photoacoustic response) arising due to absorption of a modulated laser beam by molecules of gas inside a photoacoustic cell. The photoacoustic detection is realized with an enhanced sensitivity if the modulation frequency coincides with an acoustic resonance of the cell. Therefore, the modulation frequency should be correlated with the cell-resonator sizes: the
The influence of uncertainty of emissivity on the true temperature measurement errors is considered. Expressions for the optimal spectral range of thermal flux registration, that minimize an impact of uncertainty of emissivity, are obtained. Basic operation principles and parameters of high-temperature thermal imager based on 1/3-Inch Wide-VGA CMOS Digital Image Sensor MT9V034C12STC and notebook computer are described. In contrast to thermal imagers of Mikron 9103/9104 and PyroView series, thermal image registration is performed simultaneously in three overlapping regions of near-infrared spectrum. This allows to perform the emissivity evaluation and to reduce the error in determining the temperature that arises from the uncertainty of thermal emissivity coefficient. Streszczenie. W artykule omówiono wpływ niepewności wartości współczynnika promieniowania cieplnego na błąd pomiaru rzeczywistej temperatury. Sformułowano wzory pozwalające na wybór zakresu widmowego optymalnego do rejestracji strumieni cieplnych, które minimalizują wpływ niepewności . Opisano podstawowe zasady działania i parametry wysokotemperaturowej kamery termowizyjnej na bazie 1/3-Inch Wide-VGA CMOS Digital Image Sensor MT9V034C12STC i laptopa. W przeciwieństwie do wysokotemperaturowych kamer termowizyjnych serii Mikron 9103/9104 i PyroView rejestracja obrazu termicznego jest przeprowadzana jednocześnie w trzech nakładających się częściach widma bliskiej podczerwieni, co pozwala oszacować i zmniejszyć błąd wyznaczenia temperatury wynikający z niepewności współczynnika promieniowania cieplnego (Wysokotemperaturowa trójkolorowa kamera termowizyjna).
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