Browsing by Author "Scamarcio, Gaetano"

Now showing 1 - 7 of 7
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    Highly sensitive gas leak detector based on a quartz-enhanced photoacoustic SF6 sensor
    (The Optical Society, 2016) Sampaolo, Angelo; Patimisco, Pietro; Giglio, Marilena; Chieco, Leonardo; Scamarcio, Gaetano; Tittel, Frank K.; Spagnolo, Vincenzo
    The implementation, performance validation, and testing of a gas-leak optical sensor based on mid-IR quartz-enhanced photoacoustic (QEPAS) spectroscopic technique is reported. A QEPAS sensor was integrated in a vacuum-sealed test station for mechatronic components. The laser source for the sensor is a quantum cascade laser emitting at 10.56 µm, resonant with a strong absorption band of sulfur hexafluoride (SF6), which was selected as a leak tracer. The minimum detectable concentration of the QEPAS sensor is 2.7 parts per billion with an integration time of 1 s, corresponding to a sensitivity of leak flows in the 10−9 mbar∙l/s range, comparable with state-of-the-art leak detection techniques.
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    Improved Tuning Fork for Terahertz Quartz-Enhanced Photoacoustic Spectroscopy
    (MDPI AG, 2016) Sampaolo, Angelo; Patimisco, Pietro; Giglio, Marilena; Vitiello, Miriam S.; Beere, Harvey E.; Ritchie, David A.; Scamarcio, Gaetano; Tittel, Frank K.; Spagnolo, Vincenzo
    We report on a quartz-enhanced photoacoustic (QEPAS) sensor for methanol (CH₃OH) detection employing a novel quartz tuning fork (QTF), specifically designed to enhance the QEPAS sensing performance in the terahertz (THz) spectral range. A discussion of the QTF properties in terms of resonance frequency, quality factor and acousto-electric transduction efficiency as a function of prong sizes and spacing between the QTF prongs is presented. The QTF was employed in a QEPAS sensor system using a 3.93 THz quantum cascade laser as the excitation source in resonance with a CH₃OH rotational absorption line located at 131.054 cm(-1). A minimum detection limit of 160 ppb in 30 s integration time, corresponding to a normalized noise equivalent absorption NNEA = 3.75 × 10(-11) cm(-1)W/Hz(½), was achieved, representing a nearly one-order-of-magnitude improvement with respect to previous reports.
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    Low-Loss Coupling of Quantum Cascade Lasers into Hollow-Core Waveguides with Single-Mode Output in the 3.7–7.6 μm Spectral Range
    (MDPI, 2016) Patimisco, Pietro; Sampaolo, Angelo; Mihai, Laura; Giglio, Marilena; Kriesel, Jason; Sporea, Dan; Scamarcio, Gaetano; Tittel, Frank K.; Spagnolo, Vincenzo
    We demonstrated low-loss and single-mode laser beam delivery through hollow-core waveguides (HCWs) operating in the 3.7–7.6 μm spectral range. The employed HCWs have a circular cross section with a bore diameter of 200 μm and metallic/dielectric internal coatings deposited inside a glass capillary tube. The internal coatings have been produced to enhance the spectral response of the HCWs in the range 3.5–12 µm. We demonstrated Gaussian-like outputs throughout the 4.5–7.6 µm spectral range. A quasi single-mode output beam with only small beam distortions was achieved when the wavelength was reduced to 3.7 μm. With a 15-cm-long HCW and optimized coupling conditions, we measured coupling efficiencies of >88% and transmission losses of <1 dB in the investigated infrared spectral range.
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    New approaches in quartz-enhanced photoacoustic sensing
    (SPIE, 2015) Sampaolo, Angelo; Patimisco, Pietro; Pennetta, Riccardo; Scamarcio, Gaetano; Tittel, Frank K.
    We report on the design and realization of custom quartz tuning forks with different geometries and sizes aimed to improve the photoacoustic effect in quartz-enhanced photoacoustic (QEPAS) sensor systems. A detailed analysis of the piezoelectric properties in terms of resonance frequencies, quality factors, gas damping was performed.
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    Quartz-Enhanced Photoacoustic Spectroscopy: A Review
    (MDPI, 2014) Patimisco, Pietro; Scamarcio, Gaetano; Tittel, Frank K.; Spagnolo, Vincenzo
    A detailed review on the development of quartz-enhanced photoacoustic sensors (QEPAS) for the sensitive and selective quantification of molecular trace gas species with resolved spectroscopic features is reported. The basis of the QEPAS technique, the technology available to support this field in terms of key components, such as light sources and quartz-tuning forks and the recent developments in detection methods and performance limitations will be discussed. Furthermore, different experimental QEPAS methods such as: on-beam and off-beam QEPAS, quartz-enhanced evanescent wave photoacoustic detection, modulation-cancellation approach and mid-IR single mode fiber-coupled sensor systems will be reviewed and analysed. A QEPAS sensor operating in the THz range, employing a custom-made quartz-tuning fork and a THz quantum cascade laser will be also described. Finally, we evaluated data reported during the past decade and draw relevant and useful conclusions from this analysis.
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    Single mode operation with mid-IR hollow fibers in the range 5.1-10.5 µm
    (The Optical Society, 2015) Sampaolo, Angelo; Patimisco, Pietro; Kriesel, Jason M.; Tittel, Frank K.; Scamarcio, Gaetano; Spagnolo, Vincenzo
    Single mode beam delivery in the mid-infrared spectral range 5.1-10.5 μm employing flexible hollow glass waveguides of 15 cm and 50 cm lengths, with metallic/dielectric internal layers and a bore diameter of 200 μm were demonstrated. Three quantum cascade lasers were coupled with the hollow core fibers. For a fiber length of 15 cm, we measured losses down to 1.55 dB at 5.4 μm and 0.9 dB at 10.5 μm. The influence of the launch conditions in the fiber on the propagation losses and on the beam profile at the waveguide exit was analyzed. At 10.5 µm laser wavelength we found near perfect agreement between measured and theoretical losses, while at ~5 µm and ~6 µm wavelengths the losses were higher than expected. This discrepancy can be explained considering an additional scattering loss effect, which scales as 1/λ2 and is due to surface roughness of the metallic layer used to form the high-reflective internal layer structure of the hollow core waveguide.
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    THz Quartz-enhanced photoacoustic sensor for H2S trace gas detection
    (The Optical Society, 2015) Spagnolo, Vincenzo; Patimisco, Pietro; Pennetta, Riccardo; Sampaolo, Angelo; Scamarcio, Gaetano; Vitiello, Miriam S.; Tittel, Frank K.
    We report on a quartz-enhanced photoacoustic (QEPAS) gas sensing system for hydrogen sulphide (H2S) detection. The system architecture is based on a custom quartz tuning fork (QTF) optoacoustic transducer with a novel geometry and a quantum cascade laser (QCL) emitting 1.1 mW at a frequency of 2.913 THz. The QTF operated on the first flexion resonance frequency of 2871 Hz, with a quality factor Q = 17,900 at 20 Torr. The tuning range of the available QCL allowed the excitation of a H2S rotational absorption line with a line-strength as small as S = 1.13·10−22 cm/mol. The measured detection sensitivity is 30 ppm in 3 seconds and 13 ppm for a 30 seconds integration time, which corresponds to a minimum detectable absorption coefficient αmin = 2.3·10−7 cm−1 and a normalized noise-equivalent absorption NNEA = 4.4·10−10W·cm−1·Hz-1/2, several times lower than the values previously reported for near-IR and mid-IR H2S QEPAS sensors.