16,774 Hits in 4.4 sec

Practicality of wavelength selection to improve signal-to-noise ratio in near-infrared spectroscopy

Hiroki Sato, Masashi Kiguchi, Fumio Kawaguchi, Atsushi Maki
2004 NeuroImage  
Near-infrared spectroscopy (NIRS), which can be used to detect changes in the concentration of oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) in tissue by using illumination at two  ...  Moreover, the signal-to-noise ratios (S/Ns) and wavelength dependencies of the power detected in all areas and subjects together suggest that the 692-nm pairing had the highest S/N.  ...  After the selection, the mean Hb changes in the activation periods were used to examine the signal amplitude and signal-to-noise ratio (S/N).  ... 
doi:10.1016/j.neuroimage.2003.12.017 pmid:15050579 fatcat:zwagwl4nijco5eta2346oejjoi

Continuous-wave optical parametric oscillators for mid-infrared spectroscopy

Markku M. Vainio, Peter G. Schunemann, Kenneth L. Schepler
2020 Nonlinear Frequency Generation and Conversion: Materials and Devices XIX  
In addition, the wavelength tuning range of the light source needs to be large, preferably over the entire atmospheric window, in order to enable measurements of molecular fingerprints of several compounds  ...  This sets stringent requirements for the light source of the spectrometer in terms of output power, noise, and linewidth.  ...  ACKNOWLEDGEMENTS The University of Helsinki, Business Finland, and the Academy of Finland are acknowledged for funding.  ... 
doi:10.1117/12.2548711 fatcat:ldrrqq2nczbxvojrzrqcqhqkum

Near-infrared-based Identification of Walnut Oil Authenticity

2020 DEStech Transactions on Computer Science and Engineering  
Near-infrared spectroscopy (NIR) was employed to determine the quality of walnut oil.  ...  wavelengths.  ...  Besides the intrinsic information, irrelevant information or noises were involved in the spectra acquired, leading to overlapping of spectra, low signal-to-noise ratios, low information specificity and  ... 
doi:10.12783/dtcse/cmso2019/33624 fatcat:nb3pu4lr5zevfkd4wfjlhobaty

Study on the Authenticity of Identification Methods in White Spirit by Infrared Spectrometer

Dekui Bai, Ni Wang, Quanhong Ying, Jinhui Lin
2013 Engineering  
This experiment studies on the used infrared spectroscopy to establish technology methods for liquor identification methods, as well as offers the science data for establishment of the fingerprint in white  ...  The results have shown that using near-infrared spectroscopy analysis of liquor has the obvious features such as strong specificity, good reproducibility, simple operation, and finally confirmed that it  ...  Smoothing is a common way to filter out noise, and its main function is to improve the signal-to-noise ratio, the spectrum of removing high frequency noise interference of the signal.  ... 
doi:10.4236/eng.2013.510b061 fatcat:aq72o6utojaljh53adknciqmwu

A nonlinear interferometer for Fourier-transform mid-infrared gas spectroscopy using near-infrared detection [article]

Chiara Lindner, Jachin Kunz, Simon J. Herr, Sebastian Wolf, Jens Kiessling, Frank Kühnemann
2020 arXiv   pre-print
We use methane transmission spectra around 3.3μm wavelength to characterize the spectral resolution, noise limitations and transmission accuracy of our device.  ...  In our work, we demonstrate mid-infrared transmission spectroscopy in a nonlinear interferometer using single-pixel near-infrared detection and Fourier-transform analysis.  ...  In order to increase the signal-to-noise ratio (SNR), several interferograms are added coherently.  ... 
arXiv:2011.09764v1 fatcat:6foyktqrdfdetgf7rwvnmkfv3a

Design and Experiment of a Portable Near-infrared Spectrum Detection System for Fruits and Vegetables Quality-inspection

Zheng Su, Zelong Lu, Mingyang Yang, Zhaoxin Wu, Ruoyao Xu, N. Hamid, S. Zhou
2020 E3S Web of Conferences  
To meet the practical needs of rapid and non-destructive detection in fruit and vegetable processing, this paper designs a developed portable near-infrared spectrum quality-detection device.  ...  This research can provide reference data for the design of low-cost, practical, and miniaturized near-infrared spectrum detection systems.  ...  The spectral resolution and signal-to-noise ratio can be adaptable by adjusting the size of the slit.  ... 
doi:10.1051/e3sconf/202018902009 fatcat:to2xzlegtjaxpgkutabffsxat4

Ultra-sensitive chemical vapor detection using micro-cavity photothermal spectroscopy

Juejun Hu
2010 Optics Express  
The numerical analysis shows that this technique features a record photothermal enhancement factor of 10 4 with respect to conventional cavity-enhanced (multi-pass) infrared absorption spectroscopy, and  ...  In this paper, I systematically investigated Micro-Cavity PhotoThermal Spectroscopy (MC-PTS), a novel technique for ultrasensitive detection of chemical molecular species.  ...  The author gratefully acknowledges start-up funding support from the University of Delaware.  ... 
doi:10.1364/oe.18.022174 pmid:20941119 fatcat:h52xwf3clncs7jomdcsyrgk75u

Quartz-Tuning-Fork-Enhanced Spectroscopy Based on Fast Fourier Transform Algorithm

Guangxiang Yang, Linguang Xu, Hua Liang, Jingsong Li
2020 Frontiers in Physics  
To explore the capabilities of this technique, a near-infrared (NIR) diode laser emitting at 1,653 nm and a QCTF-based photoelectric detector are developed for measuring trace methane (CH 4 ).  ...  In this paper, a gas sensing technique based on quartz-crystal-tuning-fork-enhanced spectroscopy (QCTFES) and wavelength modulation spectroscopy (WMS) is reported.  ...  Details of comparison for both demodulation methods are made with different CH4 samples, and the calculated signal-to-noise ratio (SNR) are summarized in Table 1 .  ... 
doi:10.3389/fphy.2020.582503 fatcat:yghijpxdffhmpmaw4qgcwhjo4i

Cavity-enhanced cantilever-enhanced photo-acoustic spectroscopy

Teemu Tomberg, Tuomas Hieta, Markku Vainio, Lauri Halonen
2019 The Analyst  
Highly sensitive and selective trace gas detection based on a novel photo-acoustic laser spectroscopy method.  ...  Acknowledgements We acknowledge the following funding sources: CHEMS doctoral program of the University of Helsinki, Jenny and Antti Wihuri Foundation and The Academy of Finland (grants 294752, 314363)  ...  The noise equivalent concentration achieved in our work is comparable to typical state-of-the-art results in the mid-infrared region, although the experiments here were performed in the near-infrared region  ... 
doi:10.1039/c9an00058e fatcat:u3ch4x3hpfghdc7bcuqecbrhue

Mid-infrared optical parametric oscillators and frequency combs for molecular spectroscopy

M. Vainio, L. Halonen
2016 Physical Chemistry, Chemical Physics - PCCP  
Review of mid-infrared optical parametric oscillators and frequency combs for high-resolution spectroscopy, including applications in trace gas detection and fundamental research.  ...  Acknowledgements University of Helsinki and the Academy of Finland are acknowledged for financial support.  ...  This acoustic wave at the chopping frequency can be detected with a microphone, often using lock-in detection for improved signal-to-noise ratio.  ... 
doi:10.1039/c5cp07052j pmid:26804321 fatcat:agpmjeheejfl5f37jqvk6bzqha

Research progress of optical H2O sensor with a DFB diode laser

Guangping Lv, Jun Chang, Qingpu Wang, Qiang Wang, Wei Wei
2014 Photonic Sensors  
In the field of near infrared H 2 O sensing, the acquisition of the absorption signal usually is from a noisy background, thus it is important to adopt an effective signal demodulation method.  ...  realized a better sensitive detection by one to two orders of magnitude.  ...  Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s)  ... 
doi:10.1007/s13320-014-0151-x fatcat:atmmstpu5bfu5enh6ovcki6p2a

Near-infrared trace-gas sensors based on room-temperature diode lasers

P. Werle, R. Mücke, F. D´Amato, T. Lancia
1998 Applied physics B  
Semiconductor lasers continue to find an increasing number of applications as tunable sources for highresolution spectroscopy.  ...  Near-infrared DFB lasers operating at 1.57 µm and around 2.0 µm have been used for CO 2 measurements.  ...  To reach the best signal-to-noise ratio (SNR) in frequencymodulation (FM) spectroscopy both lasers have to be operated at high currents.  ... 
doi:10.1007/s003400050510 fatcat:ngidvlpjcnc4zawu6lrsuq754u

Mid-Infrared Spectroscopy and Challenges in Industrial Environment [chapter]

Chayan Mitra
2018 Infrared Spectroscopy - Principles, Advances, and Applications [Working Title]  
weak transitions in Near-Infrared region.  ...  In recent years, Mid-Infrared spectroscopy has garnered lot of attention from researchers and industries due to the availability of industrial grade room temperature Intra-band and Quantum Cascade Lasers  ...  Near-infrared absorption spectroscopy and challenges Near-Infrared (Near-IR) (wavelength range: visible to $3 μm) Tunable Diode Laser Absorption Spectroscopy (TDLAS) is a promising technology for real-time  ... 
doi:10.5772/intechopen.80657 fatcat:ctloviha3bal7ckkksfn7jxp5a

A Trace C2H2 Sensor Based on an Absorption Spectrum Technique Using a Mid-Infrared Interband Cascade Laser

Ye Mu, Tianli Hu, He Gong, Ruiwen Ni, Shijun Li
2018 Micromachines  
In addition, the sensor can be realized by changing the wavelength of the laser to detect a variety of gases, which shows the flexibility and practicability of the proposed sensor.  ...  In this study, tunable diode laser absorption spectroscopy (TDLAS) combined with wavelength modulation spectroscopy (WMS) was used to develop a trace C2H2 sensor based on the principle of gas absorption  ...  Conflicts of Interest: The authors declare no conflict of interest.  ... 
doi:10.3390/mi9100530 pmid:30424463 pmcid:PMC6215153 fatcat:pguqs2gzbne5tcadk7w5svgcqm

Tunable Laser Diode System for Noninvasive Blood Glucose Measurements

Jonathon T. Olesberg, Mark A. Arnold, Carmen Mermelstein, Johannes Schmitz, Joachim Wagner
2005 Applied Spectroscopy  
The key to a successful optical non-invasive measurement of glucose is the collection of an optical spectrum with a very high signal-to-noise-ratio in a spectral region with significant glucose absorption  ...  To overcome these difficulties, we have developed a high-brightness tunable laser system for measurements in the 2.0-2.5 µm wavelength range.  ...  ACKNOWLEDGMENTS This research was supported by grants from the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health (DK-60657 and DK-02925).  ... 
doi:10.1366/000370205775142485 pmid:16390586 fatcat:z4cgrvlvcjc23fdoy54zgvnzo4
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