Design and Realization of Harmonic Signal Orthogonal Lock-in Amplifier Used in Infrared Gas Detection

Bing, 翟冰 Zhai; Qixin, 何启欣 He; Jian-qiang, 黄渐强 Huang; Chuantao, 郑传涛 Zheng; Yiding, 王一丁 Wang

doi:10.3788/gzxb20144311.1125001

Cited by 2 publications

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“…Calibration-free WMS is essentially a signal processing technique to extract information about molecular absorption from a noisy environment with higher signal fidelity. In view of the unsolved issues arising from potential uncertainties in laser characteristic parameters, spectroscopic constants, as well as requirements for digital filter design in the digital lock-in amplification process [107][108][109], new signal analysis methodologies have been proposed to better analyze the time-dependent signal harmonics.…”

Section: Harmonic Wavelet Analysis Of Modulated Tdlas Signalsmentioning

confidence: 99%

Laser Absorption Sensing Systems: Challenges, Modeling, and Design Optimization

Wang

Chao

2019

Applied Sciences

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Laser absorption spectroscopy (LAS) is a promising diagnostic method capable of providing high-bandwidth, species-specific sensing, and highly quantitative measurements. This review aims at providing general guidelines from the perspective of LAS sensor system design for realizing quantitative species diagnostics in combustion-related environments. A brief overview of representative detection limits and bandwidths achieved in different measurement scenarios is first provided to understand measurement needs and identify design targets. Different measurement schemes including direct absorption spectroscopy (DAS), wavelength modulation spectroscopy (WMS), and their variations are discussed and compared in terms of advantages and limitations. Based on the analysis of the major sources of noise including electronic, optical, and environmental noises, strategies of noise reduction and design optimization are categorized and compared. This addresses various means of laser control parameter optimization and data processing algorithms such as baseline extraction, in situ laser characterization, and wavelet analysis. There is still a large gap between the current sensor capabilities and the demands of combustion and engine diagnostic research. This calls for a profound understanding of the underlying fundamentals of a LAS sensing system in terms of optics, spectroscopy, and signal processing.

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Section: Harmonic Wavelet Analysis Of Modulated Tdlas Signalsmentioning

confidence: 99%

Laser Absorption Sensing Systems: Challenges, Modeling, and Design Optimization

Wang

Chao

2019

Applied Sciences

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TDLAS-WMS second harmonic detection based on spectral analysis

Jiang

Liu

et al. 2018

Review of Scientific Instruments

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A novel method for the detection of the second-harmonic component of tunable laser diode absorption spectroscopy-wavelength-modulated absorption spectroscopy is proposed in this study. The proposed method is based on spectral analysis, and the second-harmonic component is obtained in the frequency domain through a rectangular window. The validity, correctness, and noise immunity of the proposed method are verified through simulations and experiments. Experimental results demonstrate that the relative detection error level of the proposed method is <3%. In contrast to lock-in amplification, the proposed method does not require reference signals and low-pass filtering algorithms. These characteristics simplify data processing in the proposed method.

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Design and Realization of Harmonic Signal Orthogonal Lock-in Amplifier Used in Infrared Gas Detection

Cited by 2 publications

References 0 publications

Laser Absorption Sensing Systems: Challenges, Modeling, and Design Optimization

Laser Absorption Sensing Systems: Challenges, Modeling, and Design Optimization

TDLAS-WMS second harmonic detection based on spectral analysis

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