Search

Water is the only atmospheric component with three phases. In this work, ultraviolet Raman lidar is developed for synchronous measurements of water vapor, liquid water and ice water in Xi'an (34.233°N, 108.911°E), China. Different interference filters are designed to construct individual water Raman channels, and the corresponding central wavelength and bandwidth are determined by 399.0 nm (3.1 nm), 403.0 nm (5.0 nm) and 407.6 nm (0.6 nm) in ice water, liquid water and water vapor Raman channels, respectively. The mutual interference effect originating from the overlapping characteristics of water Raman spectra is further analyzed, and an accurate retrieval method based on linear simultaneous equations and mutual interference degrees is proposed for synchronous three-phase water mixing ratio profiles. Preliminary measurements are carried out in the Centre for lidar remote sensing research of Xi'an University of Technology, and representative measurement examples are obtained and validated for the performance of the Raman lidar system. Synchronous mixing ratio profiles in water vapor, liquid water and ice water are retrieved, and the corresponding extinction coefficient and relative humidity profiles are also combined to reveal the variation characteristics in three-phase waters. The possible aerosol fluorescence are analyzed as well, and it is inferred that the aerosol fluorescence might affect (possibly overestimate) the derived mixing ratio values of the liquid water and ice water. The effective detection can reach up to a height of 5 km under cloudy weather, and synchronized growth in water vapor and liquid water content is obtained in cloud layers. Continuous observations are also made under hazy weather conditions, and the temporal and spatial evolution trends of three-phase waters in clouds are successfully realized. Preliminary exploration and results validate the feasibility of ultraviolet Raman lidar for synchronous measurements of atmospheric water vapor, liquid water and ice water.

In order to investigate the biological aerosols in the atmosphere, we have designed an ultraviolet laser induced fluorescence lidar based on the lidar measuring principle. The fluorescence lidar employs a Nd:YAG laser of 266 nm as an excited transmitter, and examines the intensity of the received light at 400 nm for biological aerosol concentration measurements. In this work, we firstly describe the designed configuration and the simulation to estimate the measure range and the system resolution of biological aerosol concentration under certain background radiation. With a relative error of less than 10%, numerical simulations show the system is able to monitor biological aerosols within detected distances of 1.8 km and of 7.3 km in the daytime and nighttime, respectively. Simulated results demonstrate the designed fluorescence lidar is capable to identify a minimum concentration of biological aerosols at 5.0×10-5 ppb in the daytime and 1.0×10-7 ppb in the nighttime at the range of 0.1 km. We believe the ultraviolet laser induced fluorescence lidar can be spread in the field of remote sensing of biological aerosols in the atmosphere.

A telescope fiber coupling system using aspheric lens for coupling free-space optical field into single-mode fiber in all-fiber lidar is devised.Its layout is designed and optimized for coupling efficiency into single-mode fiber through ZEMAX software.Moreover,the preliminary experiments are carried out using the LED and laser as optical source,and then the coupling efficiencies of directive coupling and aspheric lens coupling are compared.Experimental results show that the coupling efficiency using aspheric lens for multi-mode optical source may be increased by 47% than that of directive coupling,which is close to simulating result of 45%,and that the ratio of coupling optical power for different fibers is roughly close to the square of the core-diameter ratio.Furthermore,it is shown that the coupling efficiency of this way for single-mode optical source may be raised by 20%,and that the ratio of coupling optical power is approximately 2.4 times more than the square of its core-diameter ratio,which is significant to establish the all-fiber rotational Raman lidar.

A portable micro-pulse polarization lidar system with 3D scanner at eye-safety level is developed,in which Nd∶YAG pulsed laser is employed as the exciting source with 2 μJ pulse energy and 1 kHz repetition rate,to detect the spherical characteristics and distribution of bottom aerosols in urban area.To ensure high accuracy detection near the earth's surface at the range from 80 m to 1000 m in the region of high-density aerosols such as northwest region,analog photoelectric detection technique is adopted.Continuous observations with scanning in zenith angle are carried out for the first time for depolarization ratio of atmospheric aerosols below 1 km in Xi′an in winter,the results of depolarization ratio scanning profiles are obtained and the effect of weather process and state of ground on depolarization ratio is analyzed.The experimental results show that,the depolarization ratio is around 0.1,where there were no sandstorms during the observations,and the depolarization ratio in certain regions is relative higher,which are occurred at the crossings of roads without greenbelts.The experimental results validate the feasibility of the system and will also provide scientific data for investigating the generation,transmission and diffusion characteristics of urban pollution particles.

A laser-induced fluorescence lidar has been developed for detecting the concentration of fluorescent aerosols in the air. The fluorescence lidar was constructed with a pulsed fourth-harmonic Nd:YAG laser at the ultraviolet wavelength of 266 nm with a repetition rate of 10 Hz. A 250 mm diameter custom telescope was used to collect optical spectra ranging from 260 to 560 nm. Fluorescence signals with wavelengths ranging from 310–440 nm were extracted, exploring a filter with a bandwidth of 130 nm. The preliminary experiments were conducted at the campus of Xi’an University of Technology, in which the fluorescence signals of atmospheric fluorescent aerosols were continuously collected from 20:00 to 23:00 CST on 13 December 2017. Based on the fluorescence lidar equation, the density of fluorescence signals was calibrated using Rayleigh–Mie scattering signals and ozone (O3) concentration data at the ground level. Measured ranges show a strong dependence with the O3 concentrations due to its absorption characteristics at ultraviolet 266 nm. Moreover, the concentration of the biogenic particles was also calculated based on the raw data of the fluorescence channel. Obtained results show that the concentration of biogenic particles in the Xi’an area varied greatly, ranging from 3456 particles · m−3 to 8835 particles · m−3 during winter.

A compact Mie scattering lidar system at a wavelength of 532 nm is developed to measure the optical properties of atmospheric aerosol particles and horizontal visibility.Some observations are performed and analyzed.The Fernald method is employed to retrieve the extinction coefficient of aerosol.Some continuous continual experiments are carried out for verifying the feasibility of the Mie scattering lidar at Xi'an area,and the observation results are demonstrated here by measuring the aerosol profiles of the extinction coefficient,the spatial temporal variation of atmospheric boundary layer height which are obtained within whole day at one hour interval,and the horizontal visibility which agrees with the data obtained from the local weather bureau.The observation results show that the Mie scattering lidar is capable of measuring efficiently the optical properties of atmospheric aerosol particles and horizontal visibility.

Multi-mode high-spectral-resolution lidar is a new concept of high-spectral-resolution lidar, which uses the multiple-longitudinal-mode pulsed laser rather than the single frequency laser. In this paper, we analyze the multiple longitudinal mode and its spectral distribution of a typical Nd:YAG laser, and calculate its corresponding Mie scattering and Rayleigh scattering spectra, which are a convolution between the spectral distribution of multiple-longitudinal-mode laser pulse and that of the Mie and Rayleigh scattering excited by a single frequency laser pulse. According to the spectral analyses of the elastic lidar returns, we design an ultraviolet multi-mode high-spectral-resolution lidar, in which a high-power non-seeded Nd:YAG pulsed laser at the third harmonic 355 nm wavelength is used as a transmitter, and a Cassegrain telescope serves as a receiver. In the polychromator, a narrow band interfering filter is selected to block the solar background, and a tunable Mach-Zehnder interferometer (MZI) is designed to separate the aerosol Mie scattering signals from the molecular Rayleigh scattering signals excited by the multi-mode pulsed laser. The MZI is composed of a roof mirror mounted on a piezoelectric ceramic and two beam splitters. The optical path difference of the MZI can be adjusted by the piezoelectric ceramic, while its optimum value should make the correspondence between the free spectral range of MZI and the interval between longitudinal modes of Nd:YAG pulsed laser. The photomultiplier tube is selected as a detector, whose output is the convolution between the transmission function of MZI and the Mie and Rayleigh signals excited by the multi-longitudinal mode laser pulse. In the practical experiment, the optimal optical path difference of MZI can be determined by using envelope analysis. For the transmitter laser, when one channel has a maximum output signal and the other has a minimum output, the center wavelength of each longitudinal mode of laser is locked in the optimal optical path difference. The channel of MZI with the maximum output is to pass the Mie scattering signal, while the channel with the minimum output is to block the Mie scattering signal. The aerosol optical characteristics are retrievable by using the complementary properties of the two output channels of MZI. In order to verify the feasibility of the multi-mode high spectral resolution lidar, the system simulation is carried out by using the real atmospheric model and the designed lidar system parameters. The simulation results show that the designed ultraviolet multi-mode high-spectral-resolution lidar can realize the accurate measurement of aerosol within a height of 10 km.

Rotational Raman temperature lidar for absolute measurement is an important method to directly detect the atmospheric temperature profile by using active remote sensing technology. Compared with the rotational Raman temperature relative measurement, the absolute measurement can avoid the systematic error caused by the calibration process, but its high-precision requirements of rotational Raman spectroscopic filter restrict the development of absolute measurement technique for atmosphere temperature. In order to achieve the absolute measurement technique of rotational Raman temperature lidar, the fine resolution of single rotational Raman line and the effective suppression 60-70 dB for the elastic scattering signal are the key factors for directly retrieving the atmospheric temperature by using the relationship between the single rotational Raman line and temperature. Based on the operational principle of grating, a two-stage parallel multi-channel Raman spectroscopic filter with one-order blazed grating and fiber Bragg grating is designed, and the parameters and optical path structure of the core cascade device (micron-level fiber array) are optimized. The optical path of the primary spectroscope is simulated, the wavelength difference between the rotational Raman lines of adjacent even rotational quantum numbers of nitrogen molecule (N2) gradually decreases from 0.4506 nm to 0.4475 nm. Compared with the average of approximately 0.4494 nm, its floating interval is -0.0012-+0.0019 nm, and the maximum centrifugal distortion of the rotational Raman spectra is approximately 0.0031 nm, which means that the centrifugal distortion ratio is 0.69%. Under the different values of incident angle , the diffraction position difference between adjacent rotational Raman lines varies from 124.43 m to 125.51 m, with a variation interval of -0.57-+0.51 m compared with a fixed value of 125 m. In order to test the matching consistency between rotational Raman spectra and the multi-channel fiber array, and to obtain the out-of-band suppression and channel coefficient of each fiber channel, an experimental system which consists of a first-order blazed grating, a convex lens and a fiber array is set up, and the atmospheric echo signal is simulated by using a broadband light-source and a semiconductor laser (LD). The experimental results show that the channel coefficient of the rotational Raman channels of the primary spectroscope is above 0.75, and the maximum deviation between the measured wavelength of extracted spectrum and the theoretical value is approximately 0.0398 nm, which means the the deviation degree is 8.86%. Each channel can provide more than 27 dB effective suppression to elastic scattering signal, and then by combining with the second spectroscope of fiber Bragg grating, the suppression at least is up to 62 dB. Therefore we can fine extract single rotational Raman line of even rotational quantum number.

Near-ground atmospheric aerosol has a direct effect on the living and production of human, and the research on its detection attracts substantial attention from engineers and scholars in the community of environment. Traditional monitoring instruments can accurately and continuously detect the aerosols above the ground, but it is difficult for them to obtain the information about vertical distribution of near-ground aerosols. As is well known, lidar can act as an efficient method to detect the aerosol's temporal and spatial distribution. However, this technique is restricted in the potential applications of the detection of aerosol at a certain wavelengths or near range. That is because it usually presents fixed wavelengths and a large blind area. In this work, a new multi-wavelength light-emitting diode (LED) light source radar system is designed and established for detecting the characteristics of atmospheric aerosol near ground. The paper is outlined as follows. Firstly, the composition and working principle of the LED light source radar system are introduced. Based on the structure of radar's transmitter and receiver, the geometric overlap factor is analyzed and calculated. The minimum detection height of the LED light source radar system is then determined to be 60 m. Secondly, the inversion method for the echo signal of LED light source radar is studied. In consideration of the suitability of near-range detection of LED light source radar, the Fernald forward integration method is used for inversing the aerosol extinction coefficient. The calibration value of aerosol extinction coefficient is further determined with the ground visibility data. Finally, by using the designed multi-wavelength LED light source radar system (475 nm, 530 nm, and 625 nm), near-ground aerosol observation at night in Xi'an city is carried out and three atmospheric conditions including light, moderate and severe pollution days are considered. The height distribution curves of atmospheric aerosol extinction coefficient of three wavelengths within a height of nearly 300 m are obtained. The characteristics of the distribution and change of near ground aerosols are accordingly discussed. The experimental results show that the multi-wavelength LED light source radar provides an efficient implementation for detecting the vertical distribution of atmospheric aerosol near the ground, and can make up for the inadequacy of lidar in near range detection.

A novel fluorescence lidar technique using plant fluorescence lifetime is presented to evaluate the living status for plant growth, the environmental monitoring, and so on. A 532 nm laser is used as excitation source for detecting long-range plant condition, and fluorescence signals are displayed by oscilloscope. The fluorescence lifetime can be calculated from phase plane and iterative convolution method. Phase plane method can calculate the estimated value of fluorescence lifetime by fitting the phase plane line. And iterative convolution method is used to improve the accuracy of fluorescence lifetime. The system was designed to measure the chlorophyll fluorescence lifetime. The analysis show that the test error of this method is less than 1.5 %, the method proved to be a high accuracy and real-time monitoring technology, and the correspondence between the plant chlorophyll fluorescence lifetime and the growth is obtained by repeated experiments. These characteristics show that the technique has large application potential for plant condition prediction.

An accurate aerosol optical property can be obtained by a high spectral resolution lidar (HSRL) technique, which employs a narrow spectral filter to suppress Mie scattering in the lidar return signal. The ability for filter to suppress Rayleigh scattering is critical for the HSRL. In the HSRL system, Rayleigh scattering signal is obtained and aerosol scattering is suppressed at least by a factor of 10-5 through using the narrow filter. Usually, an atomic absorption filter can reach this level. While, the gaseous absorption lines do not exist at many convenient laser wavelengths, thus restricting the development of multi-wavelength HSRL instrument. A new and practical filtering method is proposed to realize the precise detection of atmospheric optical parameters by using the reflection field of Fabry-Perot (FP) interferometer. An optical splitting system with high spectral resolution is designed and its spectral characteristics are analyzed. Based on the characteristic of hyper-spectral lidar detection signal, the variations of spectral separation ratio and Rayleigh signal transmittance with reflectivity and cavity length are discussed. Spectral separation ratio is the transmittance ratio of aerosol scattering signal to molecular scattering signal through the spectral filter. With the increases of FP cavity length and surface reflectivity, the spectral separation ratio decreases and the Rayleigh signal transmission increases. The high spectral separation ratio and Rayleigh signal transmittance can be achieved by the reflection field of FP interferometer when the FP cavity length and reflectivity parameter can be chosen reasonably. We design an FP interferometer with a cavity length of 36 mm and reflectivity of 0.4. Its spectral separation ratio is affected by the echo divergence and incidence angle. The spectral separation ratio keeps unchanged when the beam divergence angle is within 3 mrad and the incident angle of the beam is within 0.5 mrad. In addition, a simulation analysis model is established based on the error propagation. An observed actual Mie-scattering profile is used for analyzing the errors. Moreover, the influences of the divergence angle and the incident angle of the echo beam on detection results are also discussed. The results show that the proposed FP interferometer can achieve fine spectral separation of Mie and Rayleigh scattering signal, and the error of detection result is not sensitive to laser divergence angle. Fine aerosol optical parameters can be achieved when the divergence and incidence angles are controlled within 10 mrad and 1.5 mrad, respectively.

measurement methods based on Rayleigh scattering are employed to relatively detect atmospheric temperature profiles. That is to say, the definition of response functions and calibration procedures is required for temperature retrieval. Because the thermal motion rate of gas molecule complies with Maxwell distribution, and gas molecule is always in motion state, the frequency of scattering return signal generates Doppler spectral broadening. There is a positive correlation between the full width at half maximum of widened Doppler spectrum and T1/2, atmospheric absolute temperature can be obtained by measuring the Doppler spectrum shape. In this paper, the fine detection method of the spectrum shape of Rayleigh scattering and residuary Mie-scattering correction method based on solid cavity scanning Fabry-Perot (F-P) interferometer are investigated. According to the characteristics of Rayleigh scattering spectrum, the free spectral range, the geometric length of solid cavity, the type of cavity media, the full width at half maximum, the reflectivity of cavity, and the scanning step are designed. When the electro-optical crystal of KD*P with the length of 8.5 mm acts as solid cavity medium of scanning F-P interferometer, the designed free spectral region and 3 dB bandwidth are 11.5 GHz and 60 MHz at the central wavelength of 354.7 nm, respectively. The energy datum of 185 discrete points at Rayleigh scattering spectrum are obtained by using an optimized solid cavity scanning F-P interferometer with the scanning voltage of 23.5 V. A fitting spectrum is generated by employing polynomial interpolation method at the atmospheric temperature of 300 K. The maximum absolute error and full width at half maximum error of Rayleigh scattering spectrum are 22 MHz and 337 kHz, respectively. In order to verify the results, a numerical simulation of Rayleigh scattering spectrum based on standard atmosphere model and S6 model is performed. The detection uncertainty of atmospheric temperature is up to 0.8 K. As SNR (signal to noise ratio) is 10, the detection distance is 4.5 and 7.9 km at day-time and night-time, respectively. The research provides a new solution of filter system for the achievement of all-time, high-precision, and absolute detection of atmospheric temperature in the future. In meteorology, in order to investigate the temporal and spatial characteristics, the change rules and physical mechanism of weather processes, the temperature in the boundary layer of urban atmosphere is absolutely detected, where human activities are frequent and the changes of weather elements are obviously at day and night. In addition, the absolute detection method of atmospheric temperature can provide the valid means to research urban heat island, weather forecast for urban environment, and high temperature alert. In environmental studies, the absolute detection of atmospheric temperature can provide the big amount of scientific data for establishment of numerical model and research on air pollution diffusion. There is reference significance for the investigation of filter system of similar lidar. Simultaneously, the scanning filter method provides a feasible solution for the filter system with the characteristics of miniaturization, high anti-interference and high stability in the space-based platform.

Atmospheric temperature is a key parameter to characterize the state of the atmosphere. Owing to the independence of the aerosol effect for profiling the temperture, the pure rotational Raman lidar has become one of valid tools. To achieve all-time and high-precision active remote sensing, strong background noise needs to be filtered out, and the inhibition rate outside the band of more than 70 dB is needed for Mie-Rayleigh scattering in a rotational Raman temperature measurement lidar. In this paper, a multiple cascaded light path based on sampled fiber Bragg grating (SFBG) and fiber Bragg grating (FBG) in visible spectrum is presented to obtain characteristic spectrum. All-fiber spectroscopic system with high inhibition rate for Raman thermometry is set up based on the above light path. The core device consists of single mode fibers (460-HP) to ensure the compatibility with optical fiber. The main factors affecting the inhibition rate outside the band of sampled fiber Bragg grating, including refractive index modulation depth, total length of grating, sampling period and duty, are optimally designed by using mode coupling theory and tranmission matrix model. Then the optimized parameters of spectroscope are obtained. The results show that the inhibition rate outside the band is proportional to the refractive index modulation depth and duty, when the total length of grating is a constant. However, a larger sidelobe jamming will be caused by overlarge refractive index modulation depth. The less amount and widened full width half maximun of reflectivity peak appear following overlarge duty. In the Raman spectroscopic system of this paper, the inhibition rates outside the bands of SFBG and FBG are 30 dB and 20 dB, respectively. The inhibition rate of more than 70 dB is realized for Mie-Rayleigh scattering, after passing through two FBGs and one SFBG. The simulated optimum parameters of SFBGs are the effective index of the guide mode of 1.465, the saturation index variation of 0.00005, the SFBG length of 20 mm, the sampled period of 0.4 mm, and the Bragg wavelengths of 528.51 nm and 530.76 nm. By using the American standard model and atmospheric scattering signal model, the all-time signal-to-noise ratio (SNR) and inhibition rate of Mie-Rayleigh scattering and solar background light are simulated and analyzed. The results show that the intensities of solar background light and Mie-Rayleigh scattering signal are weaker than Raman scattering signals at 40 dB and 50 dB, respectively. The detection height in daytime and night can reach up to 1.6 km and 2.6 km under the condition of SNR of more than 100, respectively. Owing to these advantages such as miniaturization, anti-interference and high stability, this spectroscope provides a viable solution for filter systems of ground-based and spaceborne lidars.

A pure rotational Raman lidar has become one of valid methods of profiling atmospheric temperature. However, its proper operation generally needs a certain collocated device of atmospheric temperature to calibrate three retrieval coefficients. This fact seriously restricts the applications of pure rotational Raman lidar in the meteorology and environment fields. In order to execute the detection technique of atmospheric temperature without calibration, we present and design a pure rotational Raman lidar based on the dependence of atmosphere molecular rotational Raman spectral envelope on temperature. It is configured with a laser having a pulse energy of 300 mJ, a pulse repetition rate of 20 Hz, and a Cassegrain telescope with a clear aperture of 250 mm. A two-stage multi-channel pure rotational Raman spectroscopic filter is proposed to extract efficiently the rotational Raman spectral lines with more than 70 dB suppression to the elastic-scattering optical signals. It is configured with one blazed diffraction grating, one convex lens, one linear fiber array and seven groups of fiber Bragg gratings. The blazed diffraction grating and fiber Bragg grating are separately utilized as the primary and secondary spectroscope. The tailor-made fiber array, which is composd of ten single mode fibers of 460-HP type and one multi-mode fiber, is designed to transfer the spectral signals. One end face of multi-mode fiber lies in the focal point of telescope, and then it transfers the lidar echo signals to the pure rotational Raman spectroscopic filter. The other end face of multi-mode fiber lies in the focal point of convex lens. The ten single mode fibers are used to transfer the optical signals from the primary spectroscope to the secondary, and their end faces lie in the focal plane of convex lens. Six pure rotational Raman spectral lines of nitrogen molecule in the anti-Strokes branch are chosen under the condition of the 0.09-nm forbidden band, with the consideration of the relationship between the pure rotational Raman spectral lines of nitrogen and oxygen molecules. While the excited laser wavelength is 532 nm, their central wavelengths are 530.76 nm, 529.86 nm, 529.41 nm, 528.51 nm, 527.62 nm, and 527.17 nm, respectively. Their corresponding positions of fiber end faces on fiber array are 156 m, 407 m, 532 m, 782 m, 1031 m, and 1156 m. Compared with these pure rotational Raman spectral lines, the elastic scattering signal lies on the other side of the focal point of convex lens, which improves the spectral purity of pure rotational Raman spectral lines. A retrieval algorithm of absolute detection technique is presented based on the least square principle. The performance of this lidar is simulated based on the U. S. standard atmospheric model. Simulation results show that this designed lidar can achieve the extraction of the pure rotational Raman spectral lines of nitrogen molecules, and that the atmospheric temperature profile obtained from absolute retrieval algorithm within a measurement time of 17 min can be up to 2.0 km with less than 0.5-K deviation. This pure rotational Raman lidar without calibration will provide a new detection method and retrieval scheme for atmospheric temperature profile.

The lidar observations of aerosols under near range condition are distorted because of insufficient overlapping between the transmitting laser beam and the field of view of receiving telescope in non-coaxial lidar especially in multiwavelength lidar. However, the near-range atmosphere is closely related with human’s activity. So it is important to correct the near-range signal of multiwavelength lidar. This paper presents a novel method of correcting the near-range optical parameter of multiwavelength lidar based on aerosol particle size distribution measurements and Mie scattering theory. The near-range aerosol extinction profiles on fine day, cloudy day and foggy day are corrected. The results show that the method is convenient and feasible compared with the traditional methods. This method reduces the uncertainty of inversion and correction because the wavelength dependences of lidar ratio and the weather correlation of aerosol size distribution are taken into account. This method realizes the direct correction to near-range optical parameter of multiwavelength lidar. It is favorable and convenient to study physical and optical properties of boundary layer atmosphere by using this method. It will have a broad application and prospect.

Compared with the traditional Doppler frequency discriminator Fabry-Perot interferometer, Mach-Zehnder interferometer (MZI) has the advantages in high transmittance, linear parallel fringes instead of circular rings and wide field of view. An incoherent Doppler wind lidar system is demonstrated based on a fringe-imaging MZI. The mathematical model of wind velocity retrieval is derived, and the field widening of MZI is also used to optimize the performance of lidar system. The ideal fringe pattern outputs are obtained by numerical simulation, and the SineSqr function fitting method is proposed to determine the high-precision displacement of fringes after a Doppler shift. Furthermore, the field widening of MZI can be realized by field compensation which reduces the effect of the incidence angle on optical path difference. The results show that the wind velocity error obtained by SineSqr function fitting method is less than 0.45 m·s-1 at the line-of-sight wind velocity in a range from -100 m·s-1 to 100 m·s-1, which overcomes the instability of wind velocity retrieval by the gravity method. A full-angle field of view of 1° for MZI frequency discriminator without significant performance reduction is also achieved. These supplied discussion of the application techniques for Doppler lidar based on MZI fringe technique would promote the practical development of Doppler lidar for wind velocity measurement of the middle and upper atmosphere.

Mach-Zehnder(M-Z)interferometer can be used in Doppler lidar for wind measurement as frequency discriminator.The common M-Z interferometer′s stability is poor and not easy to adjust.A new type dual-channel M-Z interferometer was proposed as frequency discriminator based on dual prism.Through analyzing the wind measurement theory,the system was optimized and designed with optical design software.The wind velocity was retrieved from simulation result through setting experiment parameter.Compared with the theoretical wind velocity calculated from Doppler frequency shift formula,the result indicates that the retrieval simulation wind velocity agrees with theoretical wind velocity;the standard deviation is 0.46 m/s.So the new type structure can be applied in Doppler wind lidar as frequency discriminator.The optical path is easy to adjust and the system stability is improved.