The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Dong Liu - One of the best experts on this subject based on the ideXlab platform.

  • development of zju High Spectral Resolution lidar for aerosol and cloud calibration of overlap function
    Journal of Quantitative Spectroscopy & Radiative Transfer, 2020
    Co-Authors: Xue Shen, Nanchao Wang, Da Xiao, Tianfen Zhong, Chong Liu, Yudi Zhou, Igor Veselovskii, Kai Zhang, Dong Liu
    Abstract:

    Abstract Determination of overlap function is a key step in the calibration of a High-Spectral-Resolution lidar (HSRL). In this work, an iterative-based general determination (IGD) method for overlap function in HSRL is proposed. Error analysis with Monte-Carlo (MC) simulation is performed and illustrates the algorithm shows High accuracy and has High stability with an accurate lidar ratio assumption. A comparison experiment shows the overlap function from the proposed algorithm agrees well with that from a dual-field-of-view (dual-FOV) HSRL system. Since no modified optical system in HSRL is needed, this method shows great potential in real-time recording of overlap function in the HSRL system.

  • Dual-Wavelength High-Spectral-Resolution Lidar for Profiling Optical Properties of Aerosol and Cloud
    'EDP Sciences', 2020
    Co-Authors: Xue Shen, Nanchao Wang, Dong Liu, Da Xiao, Yuhang Rong, Tianfen Zhong, Chong Liu, Yupeng Zhang, Yudi Zhou, Sijie Chen
    Abstract:

    A dual-wavelength High-Spectral-Resolution lidar (HSRL) based on an iodine absorption filter and a field-widened Michelson interferometer (FWMI) has been developed to profile backscatter and extinction coefficients of aerosols and clouds accurately. This instrument was tested and calibrated on multiple observations in Hangzhou and Zhoushan, respectively, from August 2018 to April 2019. This paper discusses the design and the internal calibration method of the lidar system in detail, with several typical cases of observations and the analysis of these data products. The optical properties of urban aerosols in Hangzhou and the evolvement of clouds in Zhoushan are presented, respectively

  • retrieving the seawater volume scattering function at the 180 scattering angle with a High Spectral Resolution lidar
    Optics Express, 2017
    Co-Authors: Yudi Zhou, Dong Liu, Chong Liu, Jian Bai, Liming Yang, Zhongtao Cheng, Peijun Tang, Yupeng Zhang
    Abstract:

    A High-Spectral-Resolution lidar (HSRL) is proposed to retrieve the seawater volume scattering function at the 180° scattering angle βπ without the assumption of the lidar extinction-to-backscatter ratio. A field-widened Michelson interferometer is employed as the ultra-narrow Spectral discriminator to reject particulate scattering and molecular Rayleigh scattering but transmit molecular Mandelshtam-Brillouin scattering. The theoretical framework to retrieve βπ is presented in detail based on a dual-channel HSRL configuration. Simulation on the retrieval and error estimation shows that, the proposed oceanographic HSRL based on the ship or aircraft can perform well to extract the profile of βπ and has a real potential in the oceanographic remote sensing.

  • field widened michelson interferometer for Spectral discrimination in High Spectral Resolution lidar practical development
    Optics Express, 2016
    Co-Authors: Zhongtao Cheng, Dong Liu, Yupeng Zhang, Yudi Zhou, Jian Bai, Yongying Yang, Yibing Shen, Kaiwei Wang, Jing Luo, Chong Liu
    Abstract:

    A field-widened Michelson interferometer (FWMI), which is intended as the spectroscopic discriminator in ground-based High-Spectral-Resolution lidar (HSRL) for atmospheric aerosol detection, is described in this paper. The structure, specifications and design of the developed prototype FWMI are introduced, and an experimental approach is proposed to optimize the FWMI assembly and evaluate its comprehensive characteristic simultaneously. Experimental results show that, after optimization process, the peak-to-valley (PV) value and root-mean-square (RMS) value of measured OPD variation for the FWMI are 0.04λ and 0.008λ respectively among the half divergent angle range of 1.5 degree. Through an active locking technique, the frequency of the FWMI can be locked to the laser transmitter with accuracy of 27 MHz for more than one hour. The practical Spectral discrimination ratio (SDR) for the developed FWMI is evaluated to be larger than 86 if the divergent angle of incident beam is smaller than 0.5 degree. All these results demonstrate the great potential of the developed FWMI as the spectroscopic discriminator for HSRLs, as well as the feasibility of the proposed design and optimization process. This paper is expected to provide a good entrance for the lidar community in future HSRL developments using the FWMI technique.

  • field widened michelson interferometer for Spectral discrimination in High Spectral Resolution lidar theoretical framework
    Optics Express, 2015
    Co-Authors: Zhongtao Cheng, Dong Liu, Yupeng Zhang, Yudi Zhou, Liming Yang, Yongying Yang, Yibing Shen, Jing Luo, Lulin Duan, Kaiwei Wang
    Abstract:

    A field-widened Michelson interferometer (FWMI) is developed to act as the Spectral discriminator in High-Spectral-Resolution lidar (HSRL). This realization is motivated by the wide-angle Michelson interferometer (WAMI) which has been used broadly in the atmospheric wind and temperature detection. This paper describes an independent theoretical framework about the application of the FWMI in HSRL for the first time. In the framework, the operation principles and application requirements of the FWMI are discussed in comparison with that of the WAMI. Theoretical foundations for designing this type of interferometer are introduced based on these comparisons. Moreover, a general performance estimation model for the FWMI is established, which can provide common guidelines for the performance budget and evaluation of the FWMI in the both design and operation stages. Examples incorporating many practical imperfections or conditions that may degrade the performance of the FWMI are given to illustrate the implementation of the modeling. This theoretical framework presents a complete and powerful tool for solving most of theoretical or engineering problems encountered in the FWMI application, including the designing, parameter calibration, prior performance budget, posterior performance estimation, and so on. It will be a valuable contribution to the lidar community to develop a new generation of HSRLs based on the FWMI spectroscopic filter.

Yudi Zhou - One of the best experts on this subject based on the ideXlab platform.

  • development of zju High Spectral Resolution lidar for aerosol and cloud calibration of overlap function
    Journal of Quantitative Spectroscopy & Radiative Transfer, 2020
    Co-Authors: Xue Shen, Nanchao Wang, Da Xiao, Tianfen Zhong, Chong Liu, Yudi Zhou, Igor Veselovskii, Kai Zhang, Dong Liu
    Abstract:

    Abstract Determination of overlap function is a key step in the calibration of a High-Spectral-Resolution lidar (HSRL). In this work, an iterative-based general determination (IGD) method for overlap function in HSRL is proposed. Error analysis with Monte-Carlo (MC) simulation is performed and illustrates the algorithm shows High accuracy and has High stability with an accurate lidar ratio assumption. A comparison experiment shows the overlap function from the proposed algorithm agrees well with that from a dual-field-of-view (dual-FOV) HSRL system. Since no modified optical system in HSRL is needed, this method shows great potential in real-time recording of overlap function in the HSRL system.

  • Dual-Wavelength High-Spectral-Resolution Lidar for Profiling Optical Properties of Aerosol and Cloud
    'EDP Sciences', 2020
    Co-Authors: Xue Shen, Nanchao Wang, Dong Liu, Da Xiao, Yuhang Rong, Tianfen Zhong, Chong Liu, Yupeng Zhang, Yudi Zhou, Sijie Chen
    Abstract:

    A dual-wavelength High-Spectral-Resolution lidar (HSRL) based on an iodine absorption filter and a field-widened Michelson interferometer (FWMI) has been developed to profile backscatter and extinction coefficients of aerosols and clouds accurately. This instrument was tested and calibrated on multiple observations in Hangzhou and Zhoushan, respectively, from August 2018 to April 2019. This paper discusses the design and the internal calibration method of the lidar system in detail, with several typical cases of observations and the analysis of these data products. The optical properties of urban aerosols in Hangzhou and the evolvement of clouds in Zhoushan are presented, respectively

  • experimental determination of lidar overlap profile based on dual field of view High Spectral Resolution lidar
    EPJ Web of Conferences, 2020
    Co-Authors: Nanchao Wang, Xue Shen, Da Xiao, Yuhang Rong, Tianfen Zhong, Chong Liu, Yupeng Zhang, Yudi Zhou, Binyu Wang, Jie Chen
    Abstract:

    This paper presents two approaches to calibrate the overlap factor under inhomogeneous atmospheric condition without critical assumption and delivers detailed analysis about the retrieval errors of overlap profile in High-Spectral-Resolution-Lidar (HSRL). The first method employs an additional optical subsystem with different field-of-view, that is dual field-of-view HSRL, for the retrieval of overlap profile. The second method takes advantage of the difference of the result between the HSRL and Klett method, that is about the retrieval of backscatter coefficient for uncorrected lidar signal, to correct overlap profile. Surprisingly, two methods show very High-level consistency and stability of the result. It is potential that this technique would be an excellent solution for experimental determination of lidar overlap in ground-based HSRL.

  • retrieving the seawater volume scattering function at the 180 scattering angle with a High Spectral Resolution lidar
    Optics Express, 2017
    Co-Authors: Yudi Zhou, Dong Liu, Chong Liu, Jian Bai, Liming Yang, Zhongtao Cheng, Peijun Tang, Yupeng Zhang
    Abstract:

    A High-Spectral-Resolution lidar (HSRL) is proposed to retrieve the seawater volume scattering function at the 180° scattering angle βπ without the assumption of the lidar extinction-to-backscatter ratio. A field-widened Michelson interferometer is employed as the ultra-narrow Spectral discriminator to reject particulate scattering and molecular Rayleigh scattering but transmit molecular Mandelshtam-Brillouin scattering. The theoretical framework to retrieve βπ is presented in detail based on a dual-channel HSRL configuration. Simulation on the retrieval and error estimation shows that, the proposed oceanographic HSRL based on the ship or aircraft can perform well to extract the profile of βπ and has a real potential in the oceanographic remote sensing.

  • High-Spectral-Resolution lidar for ocean biological carbon pump studies
    OCEANS 2016 - Shanghai, 2016
    Co-Authors: Yudi Zhou, Yupeng Zhang, Zhongtao Cheng, Yongying Yang, Peituo Xu, Yibing Shen, Kaiwei Wang
    Abstract:

    Processes and strengths of the ocean's biological carbon pump are significant to the study of ocean carbon cycle. However, the development and the utilization of the ocean's biological carbon pump are greatly limited because of human's limited knowledge of the ocean. Remote sensing methods have played important roles in understanding and exploring the ocean, and the lidar is one of the most outstanding representatives for its High spatial and temporal Resolution, especially the ability of the vertical detection. High-Spectral-Resolution lidar (HSRL) employs an ultra-narrow Spectral filter to separate scattering signals between particles and water molecules without assuming a lidar ratio, and obtains the optical properties of the ocean with a High accuracy. Nevertheless, the complexity of the seawater causes variable optical properties, which gives huge potentiality to develop the HSRL working at different wavelengths in order to promote the inversion accuracy and increase the detection depth. The field-widened Michelson interferometer (FWMI), whose central transmittance can be tuned to any wavelength, can be employed as the HSRL Spectral filter and solve the problem that the operating wavelength of the iodine filter cannot change. Moreover, the FWMI has a very large field of view, which gives its superiority over Fabry-Perot interferometer that is an another popular HSRL filter. The principle of the HSRL based on the FWMI designing for the ocean remote sensing will be presented in detail. Furthermore, the availability of the application of the FWMI influenced by the disturbance of the states of Brillouin scattering is analyzed and the preliminary theory shows that the HSRL instrument basing on FWMI could be employed in the marine remote sensing with a High accuracy.

Chris A Hostetler - One of the best experts on this subject based on the ideXlab platform.

  • calibration of a High Spectral Resolution lidar using a michelson interferometer with data examples from oracles
    Applied Optics, 2018
    Co-Authors: S P Burton, Chris A Hostetler, D B Harper, A L Cook, J W Hair, S T Seaman, Salvatore Scola, J A Smith, Marta A Fenn, R A Ferrare
    Abstract:

    The NASA Langley airborne second-generation High Spectral Resolution Lidar (HSRL-2) uses a density-tuned field-widened Michelson interferometer to implement the HSRL technique at 355 nm. The Michelson interferometer optically separates the received backscattered light between two channels, one of which is dominated by molecular backscattering, while the other contains most of the light backscattered by particles. This interferometer achieves High and stable contrast ratio, defined as the ratio of particulate backscatter signal received by the two channels. We show that a High and stable contrast ratio is critical for precise and accurate backscatter and extinction retrievals. Here, we present retrieval equations that take into account the incomplete separation of particulate and molecular backscatter in the measurement channels. We also show how the accuracy of the contrast ratio assessment propagates to error in the optical properties. For both backscattering and extinction, larger errors are produced by underestimates of the contrast ratio (compared to overestimates), more extreme aerosol loading, and—most critically—smaller true contrast ratios. We show example results from HSRL-2 aboard the NASA ER-2 aircraft from the 2016 ORACLES field campaign in the southeast Atlantic, off the coast of Africa, during the biomass burning season. We include a case study where smoke aerosol in two adjacent altitude layers showed opposite differences in extinction- and backscatter-related Angstrom exponents and a reversal of the lidar ratio Spectral dependence, signatures which are shown to be consistent with a relatively modest difference in smoke particle size.

  • vertically resolved phytoplankton carbon and net primary production from a High Spectral Resolution lidar
    Optics Express, 2017
    Co-Authors: Jennifer A Schulien, Johnathan W Hair, Chris A Hostetler, Michael J Behrenfeld, Michael S Twardowski
    Abstract:

    : Passive ocean observing sensors are unable to detect subsurface structure in ocean properties, resulting in errors in water column integrated phytoplankton biomass and net primary production (NPP) estimates. Active lidar (light detection and ranging) sensors make quantitative measurements of depth-resolved backscatter (bbp) and diffuse light attenuation (Kd) coefficients in the ocean and can provide critical measurements for biogeochemical models. Sub-surface phytoplankton biomass, light, chlorophyll, and NPP fields were characterized using both in situ measurements and coincident airborne High Spectral Resolution lidar (HSRL-1) measurements collected as part of the SABOR (Ship-Aircraft Bio-Optical Research) field campaign. We found that depth-resolved data are critical for calculating phytoplankton stocks and NPP, with improvements in NPP estimates up to 54%. We observed strong correlations between coincident HSRL-1 and in situ IOP measurements of both bbp (r = 0.94) and Kd (r = 0.90).

  • airborne multiwavelength High Spectral Resolution lidar hsrl 2 observations during tcap 2012 vertical profiles of optical and microphysical properties of a smoke urban haze plume over the northeastern coast of the us
    Atmospheric Measurement Techniques, 2014
    Co-Authors: Chris A Hostetler, S P Burton, A L Cook, R A Ferrare, Detlef Muller, Eduard Chemyakin, Alexei Kolgotin, John Hair, D B Harper
    Abstract:

    Abstract. We present measurements acquired by the world's first airborne 3 backscatter (β) + 2 extinction (α) High Spectral Resolution Lidar (HSRL-2). HSRL-2 measures particle backscatter coefficients at 355, 532, and 1064 nm, and particle extinction coefficients at 355 and 532 nm. The instrument has been developed by the NASA Langley Research Center. The instrument was operated during Phase 1 of the Department of Energy (DOE) Two-Column Aerosol Project (TCAP) in July 2012. We observed pollution outflow from the northeastern coast of the US out over the western Atlantic Ocean. Lidar ratios were 50–60 sr at 355 nm and 60–70 sr at 532 nm. Extinction-related Angstrom exponents were on average 1.2–1.7, indicating comparably small particles. Our novel automated, unsupervised data inversion algorithm retrieved particle effective radii of approximately 0.2 μm, which is in agreement with the large Angstrom exponents. We find good agreement with particle size parameters obtained from coincident in situ measurements carried out with the DOE Gulfstream-1 aircraft.

  • system analysis of a tilted field widened michelson interferometer for High Spectral Resolution lidar
    Optics Express, 2012
    Co-Authors: Dong Liu, Anthony L Cook, Chris A Hostetler, Ian Miller, Johnathan W Hair
    Abstract:

    High Spectral Resolution lidars (HSRLs) have shown great value in aircraft aerosol remote sensing application and are planned for future satellite missions. A compact, robust, quasi-monolithic tilted field-widened Michelson interferometer is being developed as the Spectral discrimination filter for an second-generation HSRL(HSRL-2) at NASA Langley Research Center. The Michelson interferometer consists of a cubic beam splitter, a solid arm and an air arm. Piezo stacks connect the air arm mirror to the body of the interferometer and can tune the interferometer within a small range. The whole interferometer is tilted so that the standard Michelson output and the reflected complementary output can both be obtained. In this paper, the transmission ratio is proposed to evaluate the performance of the Spectral filter for HSRL. The transmission ratios over different types of system imperfections, such as cumulative wavefront error, locking error, reflectance of the beam splitter and anti-reflection coatings, system tilt, and depolarization angle are analyzed. The requirements of each imperfection for good interferometer performance are obtained.

  • aerosol classification using airborne High Spectral Resolution lidar measurements methodology and examples
    Atmospheric Measurement Techniques, 2011
    Co-Authors: S P Burton, Richard A. Ferrare, Johnathan W Hair, Chris A Hostetler, Anthony L Cook, D B Harper, R R Rogers, M D Obland, C F Butler, K D Froyd
    Abstract:

    Abstract. The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) on the NASA B200 aircraft has acquired extensive datasets of aerosol extinction (532 nm), aerosol optical depth (AOD) (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during 18 field missions that have been conducted over North America since 2006. The lidar measurements of aerosol intensive parameters (lidar ratio, depolarization, backscatter color ratio, and Spectral depolarization ratio) are shown to vary with location and aerosol type. A methodology based on observations of known aerosol types is used to qualitatively classify the extensive set of HSRL aerosol measurements into eight separate types. Several examples are presented showing how the aerosol intensive parameters vary with aerosol type and how these aerosols are classified according to this new methodology. The HSRL-based classification reveals vertical variability of aerosol types during the NASA ARCTAS field experiment conducted over Alaska and northwest Canada during 2008. In two examples derived from flights conducted during ARCTAS, the HSRL classification of biomass burning smoke is shown to be consistent with aerosol types derived from coincident airborne in situ measurements of particle size and composition. The HSRL retrievals of AOD and inferences of aerosol types are used to apportion AOD to aerosol type; results of this analysis are shown for several experiments.

Yupeng Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Dual-Wavelength High-Spectral-Resolution Lidar for Profiling Optical Properties of Aerosol and Cloud
    'EDP Sciences', 2020
    Co-Authors: Xue Shen, Nanchao Wang, Dong Liu, Da Xiao, Yuhang Rong, Tianfen Zhong, Chong Liu, Yupeng Zhang, Yudi Zhou, Sijie Chen
    Abstract:

    A dual-wavelength High-Spectral-Resolution lidar (HSRL) based on an iodine absorption filter and a field-widened Michelson interferometer (FWMI) has been developed to profile backscatter and extinction coefficients of aerosols and clouds accurately. This instrument was tested and calibrated on multiple observations in Hangzhou and Zhoushan, respectively, from August 2018 to April 2019. This paper discusses the design and the internal calibration method of the lidar system in detail, with several typical cases of observations and the analysis of these data products. The optical properties of urban aerosols in Hangzhou and the evolvement of clouds in Zhoushan are presented, respectively

  • experimental determination of lidar overlap profile based on dual field of view High Spectral Resolution lidar
    EPJ Web of Conferences, 2020
    Co-Authors: Nanchao Wang, Xue Shen, Da Xiao, Yuhang Rong, Tianfen Zhong, Chong Liu, Yupeng Zhang, Yudi Zhou, Binyu Wang, Jie Chen
    Abstract:

    This paper presents two approaches to calibrate the overlap factor under inhomogeneous atmospheric condition without critical assumption and delivers detailed analysis about the retrieval errors of overlap profile in High-Spectral-Resolution-Lidar (HSRL). The first method employs an additional optical subsystem with different field-of-view, that is dual field-of-view HSRL, for the retrieval of overlap profile. The second method takes advantage of the difference of the result between the HSRL and Klett method, that is about the retrieval of backscatter coefficient for uncorrected lidar signal, to correct overlap profile. Surprisingly, two methods show very High-level consistency and stability of the result. It is potential that this technique would be an excellent solution for experimental determination of lidar overlap in ground-based HSRL.

  • retrieving the seawater volume scattering function at the 180 scattering angle with a High Spectral Resolution lidar
    Optics Express, 2017
    Co-Authors: Yudi Zhou, Dong Liu, Chong Liu, Jian Bai, Liming Yang, Zhongtao Cheng, Peijun Tang, Yupeng Zhang
    Abstract:

    A High-Spectral-Resolution lidar (HSRL) is proposed to retrieve the seawater volume scattering function at the 180° scattering angle βπ without the assumption of the lidar extinction-to-backscatter ratio. A field-widened Michelson interferometer is employed as the ultra-narrow Spectral discriminator to reject particulate scattering and molecular Rayleigh scattering but transmit molecular Mandelshtam-Brillouin scattering. The theoretical framework to retrieve βπ is presented in detail based on a dual-channel HSRL configuration. Simulation on the retrieval and error estimation shows that, the proposed oceanographic HSRL based on the ship or aircraft can perform well to extract the profile of βπ and has a real potential in the oceanographic remote sensing.

  • High-Spectral-Resolution lidar for ocean biological carbon pump studies
    OCEANS 2016 - Shanghai, 2016
    Co-Authors: Yudi Zhou, Yupeng Zhang, Zhongtao Cheng, Yongying Yang, Peituo Xu, Yibing Shen, Kaiwei Wang
    Abstract:

    Processes and strengths of the ocean's biological carbon pump are significant to the study of ocean carbon cycle. However, the development and the utilization of the ocean's biological carbon pump are greatly limited because of human's limited knowledge of the ocean. Remote sensing methods have played important roles in understanding and exploring the ocean, and the lidar is one of the most outstanding representatives for its High spatial and temporal Resolution, especially the ability of the vertical detection. High-Spectral-Resolution lidar (HSRL) employs an ultra-narrow Spectral filter to separate scattering signals between particles and water molecules without assuming a lidar ratio, and obtains the optical properties of the ocean with a High accuracy. Nevertheless, the complexity of the seawater causes variable optical properties, which gives huge potentiality to develop the HSRL working at different wavelengths in order to promote the inversion accuracy and increase the detection depth. The field-widened Michelson interferometer (FWMI), whose central transmittance can be tuned to any wavelength, can be employed as the HSRL Spectral filter and solve the problem that the operating wavelength of the iodine filter cannot change. Moreover, the FWMI has a very large field of view, which gives its superiority over Fabry-Perot interferometer that is an another popular HSRL filter. The principle of the HSRL based on the FWMI designing for the ocean remote sensing will be presented in detail. Furthermore, the availability of the application of the FWMI influenced by the disturbance of the states of Brillouin scattering is analyzed and the preliminary theory shows that the HSRL instrument basing on FWMI could be employed in the marine remote sensing with a High accuracy.

  • field widened michelson interferometer for Spectral discrimination in High Spectral Resolution lidar practical development
    Optics Express, 2016
    Co-Authors: Zhongtao Cheng, Dong Liu, Yupeng Zhang, Yudi Zhou, Jian Bai, Yongying Yang, Yibing Shen, Kaiwei Wang, Jing Luo, Chong Liu
    Abstract:

    A field-widened Michelson interferometer (FWMI), which is intended as the spectroscopic discriminator in ground-based High-Spectral-Resolution lidar (HSRL) for atmospheric aerosol detection, is described in this paper. The structure, specifications and design of the developed prototype FWMI are introduced, and an experimental approach is proposed to optimize the FWMI assembly and evaluate its comprehensive characteristic simultaneously. Experimental results show that, after optimization process, the peak-to-valley (PV) value and root-mean-square (RMS) value of measured OPD variation for the FWMI are 0.04λ and 0.008λ respectively among the half divergent angle range of 1.5 degree. Through an active locking technique, the frequency of the FWMI can be locked to the laser transmitter with accuracy of 27 MHz for more than one hour. The practical Spectral discrimination ratio (SDR) for the developed FWMI is evaluated to be larger than 86 if the divergent angle of incident beam is smaller than 0.5 degree. All these results demonstrate the great potential of the developed FWMI as the spectroscopic discriminator for HSRLs, as well as the feasibility of the proposed design and optimization process. This paper is expected to provide a good entrance for the lidar community in future HSRL developments using the FWMI technique.

Zhongtao Cheng - One of the best experts on this subject based on the ideXlab platform.

  • retrieving the seawater volume scattering function at the 180 scattering angle with a High Spectral Resolution lidar
    Optics Express, 2017
    Co-Authors: Yudi Zhou, Dong Liu, Chong Liu, Jian Bai, Liming Yang, Zhongtao Cheng, Peijun Tang, Yupeng Zhang
    Abstract:

    A High-Spectral-Resolution lidar (HSRL) is proposed to retrieve the seawater volume scattering function at the 180° scattering angle βπ without the assumption of the lidar extinction-to-backscatter ratio. A field-widened Michelson interferometer is employed as the ultra-narrow Spectral discriminator to reject particulate scattering and molecular Rayleigh scattering but transmit molecular Mandelshtam-Brillouin scattering. The theoretical framework to retrieve βπ is presented in detail based on a dual-channel HSRL configuration. Simulation on the retrieval and error estimation shows that, the proposed oceanographic HSRL based on the ship or aircraft can perform well to extract the profile of βπ and has a real potential in the oceanographic remote sensing.

  • High-Spectral-Resolution lidar for ocean biological carbon pump studies
    OCEANS 2016 - Shanghai, 2016
    Co-Authors: Yudi Zhou, Yupeng Zhang, Zhongtao Cheng, Yongying Yang, Peituo Xu, Yibing Shen, Kaiwei Wang
    Abstract:

    Processes and strengths of the ocean's biological carbon pump are significant to the study of ocean carbon cycle. However, the development and the utilization of the ocean's biological carbon pump are greatly limited because of human's limited knowledge of the ocean. Remote sensing methods have played important roles in understanding and exploring the ocean, and the lidar is one of the most outstanding representatives for its High spatial and temporal Resolution, especially the ability of the vertical detection. High-Spectral-Resolution lidar (HSRL) employs an ultra-narrow Spectral filter to separate scattering signals between particles and water molecules without assuming a lidar ratio, and obtains the optical properties of the ocean with a High accuracy. Nevertheless, the complexity of the seawater causes variable optical properties, which gives huge potentiality to develop the HSRL working at different wavelengths in order to promote the inversion accuracy and increase the detection depth. The field-widened Michelson interferometer (FWMI), whose central transmittance can be tuned to any wavelength, can be employed as the HSRL Spectral filter and solve the problem that the operating wavelength of the iodine filter cannot change. Moreover, the FWMI has a very large field of view, which gives its superiority over Fabry-Perot interferometer that is an another popular HSRL filter. The principle of the HSRL based on the FWMI designing for the ocean remote sensing will be presented in detail. Furthermore, the availability of the application of the FWMI influenced by the disturbance of the states of Brillouin scattering is analyzed and the preliminary theory shows that the HSRL instrument basing on FWMI could be employed in the marine remote sensing with a High accuracy.

  • field widened michelson interferometer for Spectral discrimination in High Spectral Resolution lidar practical development
    Optics Express, 2016
    Co-Authors: Zhongtao Cheng, Dong Liu, Yupeng Zhang, Yudi Zhou, Jian Bai, Yongying Yang, Yibing Shen, Kaiwei Wang, Jing Luo, Chong Liu
    Abstract:

    A field-widened Michelson interferometer (FWMI), which is intended as the spectroscopic discriminator in ground-based High-Spectral-Resolution lidar (HSRL) for atmospheric aerosol detection, is described in this paper. The structure, specifications and design of the developed prototype FWMI are introduced, and an experimental approach is proposed to optimize the FWMI assembly and evaluate its comprehensive characteristic simultaneously. Experimental results show that, after optimization process, the peak-to-valley (PV) value and root-mean-square (RMS) value of measured OPD variation for the FWMI are 0.04λ and 0.008λ respectively among the half divergent angle range of 1.5 degree. Through an active locking technique, the frequency of the FWMI can be locked to the laser transmitter with accuracy of 27 MHz for more than one hour. The practical Spectral discrimination ratio (SDR) for the developed FWMI is evaluated to be larger than 86 if the divergent angle of incident beam is smaller than 0.5 degree. All these results demonstrate the great potential of the developed FWMI as the spectroscopic discriminator for HSRLs, as well as the feasibility of the proposed design and optimization process. This paper is expected to provide a good entrance for the lidar community in future HSRL developments using the FWMI technique.

  • field widened michelson interferometer for Spectral discrimination in High Spectral Resolution lidar theoretical framework
    Optics Express, 2015
    Co-Authors: Zhongtao Cheng, Dong Liu, Yupeng Zhang, Yudi Zhou, Liming Yang, Yongying Yang, Yibing Shen, Jing Luo, Lulin Duan, Kaiwei Wang
    Abstract:

    A field-widened Michelson interferometer (FWMI) is developed to act as the Spectral discriminator in High-Spectral-Resolution lidar (HSRL). This realization is motivated by the wide-angle Michelson interferometer (WAMI) which has been used broadly in the atmospheric wind and temperature detection. This paper describes an independent theoretical framework about the application of the FWMI in HSRL for the first time. In the framework, the operation principles and application requirements of the FWMI are discussed in comparison with that of the WAMI. Theoretical foundations for designing this type of interferometer are introduced based on these comparisons. Moreover, a general performance estimation model for the FWMI is established, which can provide common guidelines for the performance budget and evaluation of the FWMI in the both design and operation stages. Examples incorporating many practical imperfections or conditions that may degrade the performance of the FWMI are given to illustrate the implementation of the modeling. This theoretical framework presents a complete and powerful tool for solving most of theoretical or engineering problems encountered in the FWMI application, including the designing, parameter calibration, prior performance budget, posterior performance estimation, and so on. It will be a valuable contribution to the lidar community to develop a new generation of HSRLs based on the FWMI spectroscopic filter.

  • effects of Spectral discrimination in High Spectral Resolution lidar on the retrieval errors for atmospheric aerosol optical properties
    Applied Optics, 2014
    Co-Authors: Zhongtao Cheng, Dong Liu, Liming Yang, Yongying Yang, Hanlu Huang, Jing Luo, Yibing Shen
    Abstract:

    This paper presents detailed analysis about the effects of Spectral discrimination on the retrieval errors for atmospheric aerosol optical properties in High-Spectral-Resolution lidar (HSRL). To the best of our knowledge, this is the first study that focuses on this topic comprehensively, and our goal is to provide some heuristic guidelines for the design of the Spectral discrimination filter in HSRL. We first introduce a theoretical model for retrieval error evaluation of an HSRL instrument with a general three-channel configuration. The model only takes the error sources related to the Spectral discrimination parameters into account, while other error sources not associated with these focused parameters are excluded on purpose. Monte Carlo (MC) simulations are performed to validate the correctness of the theoretical model. Results from both the model and MC simulations agree very well, and they illustrate one important, although not well realized, fact: a large molecular transmittance and a large Spectral discrimination ratio (SDR, i.e., ratio of the molecular transmittance to the aerosol transmittance) are beneficial to promote the retrieval accuracy. More specifically, we find that a large SDR can reduce retrieval errors conspicuously for atmosphere at low altitudes, while its effect on the retrieval for High altitudes is very limited. A large molecular transmittance contributes to good retrieval accuracy everywhere, particularly at High altitudes, where the signal-to-noise ratio is small. Since the molecular transmittance and SDR are often trade-offs, we suggest considering a suitable SDR for Higher molecular transmittance instead of using unnecessarily High SDR when designing the Spectral discrimination filter. These conclusions are expected to be applicable to most of the HSRL instruments, which have similar configurations as the one discussed here.