scholarly journals An FPGA-based lock-in detection system to enable Chemical Species Tomography using TDLAS

2015 ◽  
Author(s):  
Andrea Chighine ◽  
Edward Fisher ◽  
David Wilson ◽  
Michael Lengden ◽  
Walter Johnstone ◽  
...  
Keyword(s):  
Detection System ◽  
Chemical Species ◽  
Lock In

LIF DETECTION OF TRACE SPECIES IN WATER USING DIFFERENT UV LASER WAVELENGTHS

2007 ◽  
Vol 17 (04) ◽  
pp. 689-695
Author(s):  
ANNA V. SHARIKOVA ◽  
DENNIS K. KILLINGER
Keyword(s):  
Detection System ◽  
Chemical Species ◽  
Excitation Wavelength ◽  
Uv Laser ◽  
Interference Filters ◽  
Trace Species ◽  
Dissolved Organic Compounds ◽  
Deep Uv ◽  
Uv Lasers ◽  
Uv Excitation

We have conducted studies of deep UV laser-induced fluorescence (LIF) for the reagentless detection of trace species and Dissolved Organic Compounds (DOC's) in water. Our LIF detection system had two interchangeable UV lasers, 266 nm and 355 nm, illuminating a flow cell containing a water sample. The fluorescence emitted at 90 degrees to the laser beam was collected by focusing optics, passed through cut-off and interference filters with 21 optical bandpass channels (240–680 nm ), and detected by a photomultiplier tube (PMT). The samples analyzed by the system included bottled, tap and river water; we have also worked with biological and chemical species (Bacillus Globigii, malathion). In terms of the excitation wavelength, it was observed that the deep UV excitation resulted in spectra that contained more features, and had better separation of the LIF from the Raman peak, thus enhancing the detection of unique spectral features.

Weak Signal Detection System Based on Lock-in Amplifier Technology

2013 ◽  
Vol 389 ◽  
pp. 489-493
Author(s):  
Yong Lv ◽  
Chun Hui Niu ◽  
Yue Qiang Li ◽  
Qing Shan Chen ◽  
Xiao Ying Li ◽  
...  
Keyword(s):  
Signal Detection ◽  
Detection System ◽  
Signal To Noise Ratio ◽  
Weak Signal ◽  
Weak Signal Detection ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Phase Sensitive ◽  
Lock In

In order to detect the weak signal deeply buried in the noise, a weak signal detection system based on lock-in amplifier is proposed. The system includes the preamplifier circuit, active low pass filter circuit, AC amplifying circuit and phase sensitive demodulation circuit. Test results show that it can greatly increase the signal-to-noise ratio (SNR) up to 12.7db.

scholarly journals Flexible lock-in detection system based on synchronized computer plug-in boards applied in sensitive gas spectroscopy

2007 ◽  
Vol 78 (11) ◽  
pp. 113107 ◽  
Author(s):  
Mats Andersson ◽  
Linda Persson ◽  
Tomas Svensson ◽  
Sune Svanberg
Keyword(s):  
Detection System ◽  
Lock In

Investigation of V(V) interaction with Humic Acid in aqueous solution using anion-exchange Ion Chromatography

2021 ◽  
Author(s):  
Lucija Knežević ◽  
Elvira Bura-Nakić
Keyword(s):  
Humic Acid ◽  
Ionic Strength ◽  
Anion Exchange ◽  
Ion Chromatography ◽  
Natural Waters ◽  
Detection System ◽  
Chemical Species ◽  
Research Report ◽  
Complexing Agent ◽  
Model Solutions

<p>The distribution of V chemical species in natural waters has been scarcely studied mainly due to its high reactivity and wide variety of co-existing forms depending on number of factors including metal concentration, pH, Eh, ionic strength, the presence of complexing ligands etc. <sup>1</sup> Importance of V speciation studies lies in the dependence of toxicity and bioavailability upon different chemical species that V takes form of in natural waters, with V(V) being most toxic and soluble <sup>4</sup>. Although thermodynamic calculations predict V(V) as dominant species in well oxidized marine environments, V(IV) is also reported to be present due to its ability to form stable complexes with Dissolved Organic Matter (DOM) related ligands found in natural waters <sup>2–6</sup>. Furthermore, previous research report that Humic Acid (HA) acts as an adsorbent and complexing agent for many trace metals (Cu<sup>2+</sup>, Zn<sup>2+</sup>, Cd<sup>2+</sup>, Fe<sup>2+</sup>). However, HA impact on V speciation and potential removal from the water column of natural aquatic systems is still unclear <sup>7</sup>.</p><p>Interaction of V(V) with HA was investigated in model solutions under different conditions using anion-exchange based Ion Chromatography with UV/Vis detection system. The goal of the research was to mimic natural conditions, as experimentally possible, in order to assess likely contribution of HA to changes in V speciation and potential removal from the solution by adsorption on HA colloids. Temporal study on V(V) reduction kinetics was conducted using strong chelator (EDTA) which was added in the filtrated solution prior to measurement in order to stabilize distribution of V species in the model solutions. Removal of V(V) from the solution on HA particles was quantified using calibration curves. Desorption experiments were performed with the addition of EDTA in un-filtrated solutions 24 hours before measurement.</p><p>Research showed that V interaction with HA is highly dependant on ionic strength of solution as well as ratios between V(V) and HA present in the solution. Desorption experiments showed almost complete recovery of V in the solutions with higher ionic strength, mainly in the form of V(IV). Observed reduction and removal of V(V) from the solution on the pH of natural waters suggest high impact of DOM on V speciation and consequently its toxicity and bioavailability.  </p><p><strong>References:</strong></p><p>1           P. N. Linnik and R. P. Linnik, Russ. J. Gen. Chem., 2018, <strong>88</strong>, 2997–3007.</p><p>2           J. P. Gustafsson, Appl. Geochemistry, 2019, <strong>102</strong>, 1–25.</p><p>3           P. Bernárdez, N. Ospina-Alvarez, M. Caetano and R. Prego, Environ. Chem., 2013, <strong>10</strong>, 42–53.</p><p>4           D. Wang and S. A. Sañudo Wilhelmy, Mar. Chem., 2009, <strong>117</strong>, 52–58.</p><p>5           K. Hirayama, S. Kageyama and N. Unohara, Analyst, 1992, <strong>117</strong>, 13–17.</p><p>6           D. Wang and S. A. Sañudo-Wilhelmy, Mar. Chem., 2008, <strong>112</strong>, 72–80.</p><p>7           Y. Yu, M. Liu and J. Yang, Chem. Ecol., 2018, <strong>34</strong>, 548–564.</p>

TDLAS using FPGA-based lock-in detection for multi-channel Chemical Species Tomography

2015 ◽  
Author(s):  
Andrea Chighine ◽  
Stylianos-Alexios Tsekenis ◽  
Edward Fisher ◽  
Nick Polydorides ◽  
David Wilson ◽  
...  
Keyword(s):  
Chemical Species ◽  
Lock In

Solar Cell Defects Detection Using Lock-In Amplifier

2012 ◽  
Vol 512-515 ◽  
pp. 276-279 ◽  
Author(s):  
Iat Fai Leong ◽  
Jing Jing Fang ◽  
Joseph Liao
Keyword(s):  
Solar Cell ◽  
High Spatial Resolution ◽  
Detection System ◽  
Signal To Noise Ratio ◽  
Ccd Camera ◽  
Inspection System ◽  
Signal To Noise ◽  
Excitation Light ◽  
Processing Control ◽  
Lock In

In this research we present a Lock-In amplifier photoluminescence image (PLI) detection system. Using a commercially available CCD camera, combined with a modulated excitation light source system, Lock-In amplifier technique is employed to enhance the sensitivity and signal-to-noise ratio of the image. Using a high resolution camera, we developed a high spatial resolution non-contact inspection system for solar cell. Each solar cell can be examined within 2s relevant for inline processing control.

Lock-in Amplifier for Pulse-Driven Quantum Cascade Lasers Gas Detection System

2016 ◽  
Vol 45 (8) ◽  
pp. 814001
Author(s):  
苗春壮 MIAO Chun-zhuang ◽  
蔺百杨 LIN Bai-yang ◽  
党敬民 DANG Jing-min ◽  
李春光 LI Chun-guang ◽  
王利军 WANG Li-jun ◽  
...  
Keyword(s):  
Quantum Cascade Lasers ◽  
Detection System ◽  
Gas Detection ◽  
Quantum Cascade ◽  
Lock In ◽  
Cascade Lasers
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