The theoretical and experimental exploration of a novel water-vapor concentration measutrment scheme based on scanning spectrometry

Zhang, Yan; Chang, Jun; Wang, Qiang; Zhang, Shi-cong; Song, Fujun

doi:10.1109/iceoe.2011.6013493

Cited by 8 publications

(6 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The fundamentals of the molecular absorption spectroscopy have been discussed widely elsewhere [5,6]. According to the HITRAN2008 database, many gas species exhibit absorption in the ultraviolet (UV), visible, near infrared or mid infrared regions.…”

Section: Basic Principlesmentioning

confidence: 99%

Research progress of optical H2O sensor with a DFB diode laser

Chang

Wang

et al. 2014

Photonic Sens

Self Cite

View full text Add to dashboard Cite

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. This study introduced the research progress in the field of trace water vapor detection, covering different individual gas detection techniques. On the basis of the conventional double-beam differential absorption, the division method in voltage and the dual-peak method based on the differential value of two adjacent absorption lines have been studied. Voltage division has an excellent stability to temperature variation, mechanical extrusion, and fiber bend loss. The dual-peak method proved a linear relation with the water vapor concentration, and this method provided a way to measure the concentration at high pressure. Furthermore, the so called balanced ratiometer detection (BRD) was introduced. It has an outstanding self-adjusting capability, and it can also avoid an excess phase difference caused by the current-to-voltage converting circuit, thus this method has a high sensitivity. In addition, the second harmonic technique applied to gas detection was introduced, and for the high-frequency modulation via driving current, 1/f was suppressed apparently; as a result, this technique realized a better sensitive detection by one to two orders of magnitude.

show abstract

Section: Basic Principlesmentioning

confidence: 99%

Research progress of optical H2O sensor with a DFB diode laser

Chang

Wang

et al. 2014

Photonic Sens

Self Cite

View full text Add to dashboard Cite

show abstract

“…Thus, reliability is an important index for evaluating the technical performance of DWMS. Subtraction [7], division [8], and balanced ratiometric detection (BRD) [9,10] are three known demodulation methods employed extensively for dual-beam wavelengthmodulation trace gas detection. The difference in the reliability of these demodulating systems under changing environmental factors has not attracted enough attention.…”

Section: Introductionmentioning

confidence: 99%

Reliability analysis and comparison of demodulation methods for dual-beam wavelength-modulation spectroscopy water vapor detection

et al. 2013

Self Cite

View full text Add to dashboard Cite

Subtraction, division, and balanced ratiometric detection (BRD) are three extensively used demodulation methods for dual-beam wavelength-modulation trace gas detection. However, reliability comparisons among these methods under changing environmental conditions were rarely researched. In this paper, the influences of ambient temperature and bend loss of fibers are analyzed in detail, and the reliabilities of the subtraction, division, and BRD methods are quantitatively compared for the first time to our knowledge. When the ambient temperature is increased by 1°C, the deviation of the division method is only 0.29%, which obviously outperforms the subtraction method (2.90%) and the BRD method (0.55%). Furthermore, a concept, "power fluctuation rejection ratio," is introduced to compare the suppression effects of the subtraction, division, and BRD methods on the laser light source power fluctuation. The study results demonstrate that the division method provides better reliability when the ambient temperature or bending loss is varied. The validity and reliability are fully verified by the fact that the experimental results give good agreement with the theoretical simulation.

show abstract

“…Wavelength of laser diode could be current-modulated rapidly, and this advantage is usually used by a signal averager to increase the signal-to-noise ratio (SNR) during laser absorption measurement. [5] The most common method used in a spectrum absorption type gas sensor is to utilize double-beam differential absorption [6,7]. With this method, the output of a laser diode is split into a signal and a reference-beam.…”

Section: Introductionmentioning

confidence: 99%

High-sensitive measurement of water vapor: shot-noise level performance via a noise canceller

et al. 2013

Self Cite

View full text Add to dashboard Cite

Taking advantages of distributed feedback laser diode a technique is described to achieve high-sensitive measurement for water vapor concentration. This technique, with a modified balanced ratio metric detection system, has improved the accuracy of measured absorption spectrum by two main aspects. Improvement by matching equivalent conductivity of signal or reference photo detector (PD) is presented, and with the additional matched resistance suppression for the power variation in the signal-beam has been improved from 53 to 88 dB. The importance of integrating amplifier bandwidth design from the circuit to the measured absorption spectrum has been demonstrated in our experiment. For a scan rate of 32 Hz with an optimal corresponding bandwidth of 15.9 kHz, the absorption spectrum is well described by Voigt profile, with a difference of 1% at an atmosphere pressure of 1 atm and a room temperature of 296 K. With the application of averaging and filtering, absorption sensitivity of 1.093×10(-6) for water vapor at 1368.597 nm has been demonstrated, and the corresponding concentration is 71.8 ppb in just a 10 cm path length.

show abstract

The theoretical and experimental exploration of a novel water-vapor concentration measutrment scheme based on scanning spectrometry

Cited by 8 publications

References 8 publications

Research progress of optical H2O sensor with a DFB diode laser

Research progress of optical H2O sensor with a DFB diode laser

Reliability analysis and comparison of demodulation methods for dual-beam wavelength-modulation spectroscopy water vapor detection

High-sensitive measurement of water vapor: shot-noise level performance via a noise canceller

Contact Info

Product

Resources

About