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Topic: TDLAS


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In the News (Thu 10 Dec 09)

  
  R AND D OZONE PRECURSOR METHODS
Tunable Diode Laser Absorption Spectroscopy (TDLAS) uses a diode laser as the excitation light source for the absorption spectroscopic measurement.
TDLAS has been used typically in the measurement of trace gases in the lower and upper atmosphere.
TDLAS is a fast detection technique, and is specific to the analyte of interest.
narsto.esd.ornl.gov /Compendium/methods/TDLAS.html   (726 words)

  
 [No title]   (Site not responding. Last check: 2007-10-12)
TDLAS is a spectroscopic technique utilizing lead salt diode lasers.
Multipass cells are used to increase the pathlengths to 100's of meters thereby increasing the sensitivity.
TDLAS can be used to measure a number of trace gases of atmospheric importance.
www.cac.yorku.ca /people/harris/harris-links/midir.html   (200 words)

  
 MICRO: Ultraure Gases - McAndrew (Feb 2000)
TDLAS performs trace moisture measurements in process chambers and pure gases, achieving sensitivity in the low-parts-per-billion range and fast response times.
TDLAS has an advantage over other spectroscopic methods in that the diode laser can be operated in a relatively high-frequency modulation regime, where its noise contribution is very low.
TDLAS has been used successfully to monitor the initial moisture release from a dry electropolished stainless-steel pipe in HCl.
www.micromagazine.com /archive/00/02/mcandrew.html   (4410 words)

  
 Abstract
In this paper the concept of the Allan variance is utilized to analyze the stability of an existing frequency modulated (FM) TDLAS instrument leading to a detection limit for NO of 34 pptv at 6 Hz detection bandwidth.
Substantial improvements of tunable diode laser absorption spectroscopy (TDLAS) with respect to detection speed and detection limits were obtained by introducing high frequency modulation schemes, but the expected quantum limited performance with optical multipass cells has not been attained yet on a routine basis.
This paper is primarily devoted to the question, how refractive index fluctuations, generated by a turbulent gas flow through an optical multipass cell, affect the phase of a frequency modulated laser beam and, therefore, influence the performance of highly sensitive spectroscopic measurements.
members.aol.com /FMTDLAS/abstract.htm   (2550 words)

  
 Research Abstract: 1997-01-28 Development Of An Acid Deposition Model For the South Coast Air Basin
The nitric acid data obtained by tunable laser diode spectroscopy (TDLAS) in October 1993 in Azusa, CA were reviewed to evaluate their accuracy and hence suitability as a reference standard for the measurements made by CADMP, SCAQS-type, and two-week denuder samplers.
The two-week sampler measurement was 30% higher than the TDLAS integrated value for the same two-week period.
Based on previous observations of the daytime nitric acid to ozone ratios in Azusa and other locations in the South Coast Air Basin, the TDLAS nitric acid measurements in Azusa during the 1993 study were significantly higher than expected.
www.arb.ca.gov /research/abstracts/93-340.htm   (363 words)

  
 Moisture Analyzer. TDLAS Technology Moisture Analyzer Sensor - Delta F
TDLAS is a spectroscopic technique that uses a diode laser as its light source.
TDLAS has advantages over other techniques because the moisture sample only comes in contact with a few optical components that are made from very robust materials.
Our TDLAS moisture analyzers are designed and built to provide years of trouble-free, reliable operation.
www.delta-f.com /moisture.html   (261 words)

  
 Moisture Analyzer. Moisture Sensing Technology. TDLAS Technology Moisture Analyzer Sensor - Delta F
TDLAS is a spectroscopic technique that utilizes a diode laser as its light source.
By rapidly tuning the laser, Delta F's TDLAS technology uses a single light source, a single light path and a single detector and, therefore, does not require any recalibration.
Delta F's TDLAS technology offers a robust and simple optical design with the sample and reference measured with a single laser source and a single detector.
www.delta-f.com /moistureprod.html   (390 words)

  
 Consumer Information: Air Pollution Research Report/Studies- Mobile Sources
The most consistent sets of HNO3 data for comparison were those for the October 13 - October 24 period, which showed that the TDLAS results were about 30% higher than the SCAQS values and approximately 45% greater than the CADMP values (the latter were average of measurements by the primary and secondary CADMP samplers).
An HNO3 : O3 ratio of 0.1 with good correlation was shown by the secondary CADMP sampler, thus indicating a high probability that its measurements for the total period July - October 1993 were correct.
The TDLAS HNO3 time profiles, when examined with those of the concurrent O3 and PAN profiles, showed no evidence of a nitric acid adsorption/desorption process occurring along the sampling train nor evidence of nitric acid vaporization from particulates on the Teflon front-filter.
www.arb.ca.gov /research/resnotes/notes/93-340.htm   (313 words)

  
 Picarro Instruments Product FAQs   (Site not responding. Last check: 2007-10-12)
Traditional TDLAS approaches may achieve a modest increase in optical path length, using a White Cell or Herriott Cell, and practically limited by mirror manufacture and alignment.
Because TDLAS instruments measure the ratio of the absorbed to incident light, sensitivity can also be impacted by noise from the light source, mirrors, and detector.
CRDS measures the time for photon energy to dissipate from inside the cavity and is relatively insensitive to noise from the light source, mirrors, and detector.
www.picarro.com /instruments_2_3.htm   (568 words)

  
 NS4167en - NEW GENERATION OF TDLAS GAS MONITORS FROM NORWAY
NEO is one of Norway's principal research companies in the electro-optics field, working with industrial partners and with research institutes on national and international projects.
Unlike conventional UV or IR spectrographic instruments, NEO Monitors' instruments employ the measurement principle known as 'single line spectroscopy', which eliminates cross interference from other gases and enables very low concentrations of gas to be detected.
The company is currently the largest commercial supplier of TDLAS gas monitors for industrial applications.
www.eibis.com /eibis/eibiswww/eibisdoc/4167en.htm   (586 words)

  
 Zolo Technologies, Inc.
Here we describe results obtained during a preliminary measurement campaign from a novel combustion sensor based upon multiplexed tunable diode laser spectroscopy (TDLAS) applied to coal-fired electric utility boilers.
This article details collaboration between researchers in Dr. Ronald Hanson's group at Stanford University's High Temperature Gasdynamics Laboratory and Zolo Technologies, Inc. A multiplexed spectroscopy sensor or "MSS" based on tunable diode laser spectroscopy (TDLAS) is the fruit of this joint effort.
TDLAS is now considered a mature laboratory technique for combustion diagnostics thanks to the efforts of Dr. Hanson's group at Stanford and a handful of other groups spread over the world.
www.zolotech.com /sub/about-us/white-papers.php   (263 words)

  
 ATD Annual Scientific Report 2004
With this in mind, a comparison of these two figures immediately reveals that the DFG system is significantly smaller than the TDLAS system; the DFG-Herriott cell configuration in Fig.
Rather than risk flying such a system for the first time during a critical field mission, we decided to pursue the more prudent course of action by employing the TDLAS system during the 2004 summer INTEX-NA study.
However, numerous small modifications were implemented to this system this past year to further improve the system robustness, reliability, and performance.
www.atd.ucar.edu /dir_off/ASR/FY2004/narrative_developments.html   (3423 words)

  
 1999 Fire Publications - Obtaining and Interpreting Near-Infrared Wavelength Modulation Absorption Signals From Hot ...   (Site not responding. Last check: 2007-10-12)
Researchers at NIST are presently studying the possible application of near-infrared TDLAS for rapid measurement of CO concentration in and around fires.
Near-infrared diodes are compact, spectrally narrow, and rapidly tunable, and the potential exists to deliver diode light into and out of real-scale fires using rugged and readily-available silica fiber optics.
Some recent studies of CO in combustion gases employed rapid probe sampling with a multi-pass cell/diode laser arrangement, and an in situ measurement of CO concentration in the hot exhaust of a premixed methane/air flame was recently reported.
fire.nist.gov /bfrlpubs/fire99/art114.html   (283 words)

  
 Tunable Diode Laser Absorption Spectroscopy (TDLAS.com): About TDLAS.com   (Site not responding. Last check: 2007-10-12)
Until recently, TDLAS for gas analysis was suitable for laboratory use only, requiring highly trained individuals to operate high-maintenance devices and provide expert interpretation of the outputs.
During the past decade, however, the technology has emerged from the laboratory to become a reliable, robust, and (for selected industrial applications) commercially available means for continuously measuring and, in some cases, controlling extremely small concentrations of selected trace gas species.
Based on semiconductor laser chips that operate at room temperature and transmit light through optical fibers, TDLAS gas analyzers are attractive for continuous in-situ measurements to monitor and control chemical, combustion, or manufacturing processes in harsh, hazardous, or difficult to access industrial environments.
www.tdlas.com   (228 words)

  
 [No title]   (Site not responding. Last check: 2007-10-12)
The emission from a diode laser is scanned across a spectral feature.
The laser line is very narrow in frequency, making TDLAS a powerful technique for measurements on the narrow lines of gases at low pressure.
A comprehensive review of TDLAS has recently been published by Schiff, et al.
www.infraredanalysisinc.com /t1.htm   (95 words)

  
 TDLAS   (Site not responding. Last check: 2007-10-12)
Tuneable Diode Laser Absorption Spectroscopy (TDLAS) is a technique that makes use of a tuneable diode laser to scan in wavelength across an absorption line of an atomic or molecular species that one wishes to investigate in a flow.
In our work, we are interested in investigating the water molecule because it is a combustion product produced by a hydrogen-fuelled scramjet and will therefore provide information related to the combustion efficiency in the engine.
Follow the links on this page to view the general experimental layout, the application of the technique to the scramjet and some results in a test cell
elroy.anu.edu.au /~frank/houwing/tdlas.htm   (115 words)

  
 WUR - Meteorologie en Luchtkwaliteit - Meteorology and Air Quality   (Site not responding. Last check: 2007-10-12)
Combination of the gradient and the coefficient of exchange provide the methane flux in that area.
Can the TDLAS in open paths configuration be used for emission measurements?
A&F report on Measurement methods for agricultural emissions; chapter on TDLAS measurements, Seo proposal on TDLAS for A&F. Available data/instruments:
www.met.wau.nl /education/thesis/las_methane.html   (109 words)

  
 [No title]   (Site not responding. Last check: 2007-10-12)
Recent technological advances in the field of communications have made near-IR tundable diode lasers (TDLs) of high quality, yet relatively inexpensive.
A TDL Absorption Spectrometer (TDLAS) system is currently being developed utilizing two-tone frequency modulation to measure trace atmospheric species using a long, open-path.
Although the vibrational transitions in the near-IR are weak (overtones and combinations) compared to the mid-IR (fundamentals), working in the near-IR offers several advantages:
www.cac.yorku.ca /people/harris/harris-links/nearir.html   (213 words)

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