On-line wavelength calibration of pulsed laser for CO2 DIAL sensing

Han, Ge; Gong, Wei; Lin, Hong; Ma, Xin; Xiang, Chengzhi

doi:10.1007/s00340-014-5925-8

Cited by 11 publications

(6 citation statements)

References 30 publications

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“…Therefore, we focus on frequency drift of the on-line wavelength herein. The frequency drift induced error reaches its peak at the wings of a CO2 spectrum, while it falls to a much lower value at the absorption peak according to previous studies [39,59,60]. Consequently the on-line wavenumber could move to the absorption peak of the CO2 spectrum and the error would decrease by one order of magnitude, as also shown in Figure 9.…”

Section: Estimation Of the Systematic Errormentioning

confidence: 60%

Feasibility Study on Measuring Atmospheric CO2 in Urban Areas Using Spaceborne CO2-IPDA LIDAR

Han

Gong

et al. 2018

Remote Sensing

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Abstract:Since over 70% of carbon emissions are from urban areas, it is of great importance to develop an effective measurement technique that can accurately monitor atmospheric CO 2 in global urban areas. Remote sensing could be an effective way to achieve this goal. However, due to high aerosol loading in urban areas, there are large, inadequately resolved areas in the CO 2 products acquired by passive remote sensing. China is planning to launch the Atmospheric Environment Monitoring Satellite (AEMS) equipped with a CO 2 -light detecting and ranging (LIDAR) system. This work conducted a feasibility study on obtaining city-scale column CO 2 volume mixing ratios (XCO 2 ) using the LIDAR measurements. A performance framework consisting of a sensor model, sampling model, and environmental model was proposed to fulfill our demand. We found that both the coverage and the accuracy of the LIDAR-derived city-scale XCO 2 values were highly dependent on the orbit height. With an orbit height of 450 km, random errors of less than 0.3% are expected for all four metropolitan areas tested in this work. However, random errors of less than 0.3% were obtained in only two metropolitan areas with an orbit height of 705 km. Our simulations also showed that off-nadir sampling would improve the performance of a CO 2 -Integrated Path Differential Absorption (IPDA) LIDAR system operating in a 705 km orbit. These results indicate that an active remote sensing mission could help to effectively measure XCO 2 values in urban areas. More detailed studies are needed to reveal the potential of such equipment for improving the verification of carbon emissions and the estimation of urban carbon fluxes.

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Section: Estimation Of the Systematic Errormentioning

confidence: 60%

Feasibility Study on Measuring Atmospheric CO2 in Urban Areas Using Spaceborne CO2-IPDA LIDAR

Han

Gong

et al. 2018

Remote Sensing

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“…The laser of the target wavelength is generated via difference frequency mixing between the fundamentals of the Nd:YAG laser (1064 nm) and the dye laser (634 nm), which is pumped by the second harmonic of the Nd:YAG (532 nm). As a consequence, the wavelength of the output laser can be changed by tuning the dye laser whose wavelength is changed by a stepper motor [30]. In the DIAL system, the high-precision frequency calibration of the on-line wavelength has a significant influence on inversion precision.…”

Section: Methodsmentioning

confidence: 99%

Wavelet modulus maxima method for on-line wavelength location of pulsed lidar in CO_2 differential absorption lidar detection

et al. 2016

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Differential absorption lidar (DIAL) is an excellent technology for atmospheric CO 2 detection. However, the accuracy and stability of a transmitted on-line wavelength are strictly required in a DIAL system. The fluctuation of a tunable pulsed laser system is relatively more serious than that of other laser sources, and this condition leads to a large measurement error for the lidar signal. These concerns pose a significant challenge in on-line wavelength calibration. This study proposes an alternative method based on wavelet modulus maxima for the accurate on-line wavelength calibration of a pulsed laser. Because of the different propagation characteristics of the wavelet transform modulus maxima between signal and noise, the singularities of a signal can be obtained by detection of the local modulus maxima in the wavelet transform maximum at fine scales. Simulated analysis shows that the method is more accurate than the general method such as quintic polynomial fitting and can steadily maintain high calibration precision at different signal-to-noise ratios (SNRs). Last, 16 groups of real experiments were conducted to verify the simulated analysis, which shows that the proposed method is an alternative for accurately calibrating an on-line wavelength. In addition, the proposed method is able to suppress noises in the process of wavelength calibration, which gives it an advantage in accurate on-line wavelength calibration with a low SNR.

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“…One of the broadening mechanisms produces a Gaussian profile as a result of the Doppler broadening; the other produces a Lorentz profile. Because of its physical implications, the Voigt function is superior to other functions for obtaining the absorption line of CO 2 [25]. The H 2 O curve, which marks the right axis, is on a log scale, given that the intensities of the lines are much smaller than those of CO 2 .…”

Section: Simulation Analysismentioning

confidence: 99%

“…In the laboratory experiments of DW-DIAL, the absorption spectra of CO 2 was first obtained using a gas cell with a large scale of approximately 10 pm, and the absorption spectra of CO 2 at the region of R16 was located using a wavemeter whose accuracy was approximately 5 pm. After locating R16, we conducted a fine scanning at a step size of 3 pm and obtained the location of the on-line wavelength using a wavelength stabilization program, about which a detailed introduction is in [25]. The laser of the on-line wavelength was then imported into the gas absorption cell of the 16-m range, and the OD was obtained using the oscilloscope, following the collection procedures.…”

Section: Experiments With Laboratory Signalmentioning

confidence: 99%

“…The target wavelength is generated through difference frequency mixing between the fundamentals of the Nd:YAG laser (1064 nm) and the dye laser (634 nm), which is pumped by the second harmonic of the Nd:YAG (532 nm). Consequently, the wavelength of the output laser can be changed by tuning the dye laser, whose wavelength is changed by a stepper motor [25]. The different transmitted wavelengths are then vertically launched into the air.…”

Section: Introductionmentioning

confidence: 99%

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Feasibility Study of Multi-Wavelength Differential Absorption LIDAR for CO2 Monitoring

Xiang

Liang

et al. 2016

Atmosphere

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Abstract:To obtain a better understanding of carbon cycle and accurate climate prediction models, highly accurate and temporal resolution observation of atmospheric CO 2 is necessary. Differential absorption LIDAR (DIAL) remote sensing is a promising technology to detect atmospheric CO 2 . However, the traditional DIAL system is the dual-wavelength DIAL (DW-DIAL), which has strict requirements for wavelength accuracy and stability. Moreover, for on-line and off-line wavelengths, the system's optical efficiency and the change of atmospheric parameters are assumed to be the same in the DW-DIAL system. This assumption inevitably produces measurement errors, especially under rapid aerosol changes. In this study, a multi-wavelength DIAL (MW-DIAL) is proposed to map atmospheric CO 2 concentration. The MW-DIAL conducts inversion with one on-line and multiple off-line wavelengths. Multiple concentrations of CO 2 are then obtained through difference processing between the single on-line and each of the off-line wavelengths. In addition, the least square method is adopted to optimize inversion results. Consequently, the inversion concentration of CO 2 in the MW-DIAL system is found to be the weighted average of the multiple concentrations. Simulation analysis and laboratory experiments were conducted to evaluate the inversion precision of MW-DIAL. For comparison, traditional DW-DIAL simulations were also conducted. Simulation analysis demonstrated that, given the drifting wavelengths of the laser, the detection accuracy of CO 2 when using MW-DIAL is higher than that when using DW-DIAL, especially when the drift is large. A laboratory experiment was also performed to verify the simulation analysis.

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On-line wavelength calibration of pulsed laser for CO2 DIAL sensing

Cited by 11 publications

References 30 publications

Feasibility Study on Measuring Atmospheric CO2 in Urban Areas Using Spaceborne CO2-IPDA LIDAR

Feasibility Study on Measuring Atmospheric CO2 in Urban Areas Using Spaceborne CO2-IPDA LIDAR

Wavelet modulus maxima method for on-line wavelength location of pulsed lidar in CO_2 differential absorption lidar detection

Feasibility Study of Multi-Wavelength Differential Absorption LIDAR for CO2 Monitoring

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