This PDF file contains the front matter associated with SPIE Proceedings Volume 10791, including the Title Page, Copyright information, Table of Contents, Introduction, Author and Conference Committee lists

Here we report on the development of a new coherent-DIAL system as well as first quantitative measurements of simultaneous gas mixing ratio and radial wind-speed with the instrument. Integrated measurement of atmospheric methane (CH₄) mixing ratio between the instrument and a hard-target located at 2:25 km has been conducted with a relative precision of nearly 20% in 17 s. The measurement procedure also gives information on integrated water vapor (H₂O) mixing ratio.

The progress toward developing a technique for the underwater remote detection of gases using Raman lidar is reported. In this work, we describe the development of the marine Raman lidar system for monitoring the CH4 gas of Taketomi submarine hot spring. The transmitter of lidar system was the third harmonic of a standard Q-switched Nd:YAG laser (355 nm). The receiver of this system consisted by a telescope with a diameter of 200 mm, a spectrometer, a CCD camera for measuring Raman spectrum, and a PMT for monitoring Raman lidar signals. In order to evaluate the performance of our system, we demonstrated the Raman spectroscopic measurements from a barge down to the water depth of about 30 m.

The results of the development of a mid-IR differential absorption lidar based on the optical parametric oscillator (OPO) are presented. The receiving and transmitting parts of the OPO-lidar are described. The sounding efficiency of trace atmospheric gases in the mid-IR using an OPO lidar system developed is experimentally estimated. Echo signals of the OPO-lidar system in the mid-IR are experimentally detected.

Our understanding of the Mars atmosphere and the coupled atmospheric processes that drive its seasonal cycles is limited by a lack of observation data, particularly measurements that capture diurnal and seasonal variations on a global scale. As outlined in the 2011 Planetary Science Decadal Survey and the recent Mars Exploration Program Analysis Group (MEPAG) Goals Document, near-polar-orbital measurements of height-resolved aerosol backscatter and wind profiles are a high-priority for the scientific community and would be valuable science products as part of a next-generation orbital science package. To address these needs, we have designed and tested a breadboard version of a direct detection atmospheric wind lidar for Mars orbit. It uses a single-frequency, seeded Nd:YAG laser ring oscillator operating at 1064 nm (4 kHz repetition rate), with a 30-ns pulse duration amplified to 4 mJ pulse energy. The receiver uses a Fabry-Perot etalon as part of a dual-edge optical discrimination technique to isolate the Doppler-induced frequency shift of the backscattered photons. To detect weak aerosol backscatter profiles, the instrument uses a 4x4 photon-counting HgCdTe APD detector with a 7 MHz bandwidth and < 0.4 fW/Hz^1/2 noise equivalent power. With the MARLI lidar breadboard instrument, we were able to measure Doppler shifts continuously between 1 and 30 m/s by using a rotating chopper wheel to impart a Doppler shift to incident laser pulses. We then coupled the transmitter and receiver systems to a laser ranging telescope at the Goddard Geophysical and Astronomical Observatory (GGAO) to measure backscatter and Doppler wind profiles in the atmosphere from the ground. We measured a 5.3 ± 0.8 m/s wind speed from clouds in the planetary boundary layer at a range of 4 to 6 km. This measurement was confirmed with a range-over-time measurement to the same clouds as well as compared to EMC meteorological models. Here we describe the lidar approach and the breadboard instrument, and report some early results from ongoing field experiments.

A wavelength tunable near-infrared laser for use in remote target classification is demonstrated. The laser operates in the range of 1290 nm to 1650 nm and has power output within eye-safety limits. The preliminary results of laboratory tests of remote classification of materials indicate are shown.

Validating and improving the global atmospheric transport model, therefore, requires precise measurement of the CO2 concentration profile. The differential absorption lidar (DIAL) is thought to be one of the best methods for observing the vertical distribution of greenhouse gases. One of its main advantages over other passive methods is its capacity for taking continuous measurements that provide high spatial and temporal resolutions of CO2. We had developed a ground based direct detection 1.6 μm DIAL to achieve measurements of vertical CO2 profiles. As the spectra of absorption lines of any molecules are influenced basically by the air temperature, it is important to measure the air temperature simultaneously. Then, we have improved the 1.6 μm DIAL system for simultaneous measurements of the CO2 concentration and temperature profiles in the lower-atmosphere. We conducted a field experiment to compare the new DIAL measurements with in situ sensor measurements. An open-path CO2 gas analyzer (LICOR. Inc., LI-7500) and temperature sensor (T&D TR-72Ui) were installed at the top of the building at a height of 42 m. The average difference in the CO2 concentration measured by the DIAL and LI-7500 was −0.01 ± 2.1 ppm. The average difference in the atmospheric temperature measured by the DIAL and TR-72Ui was −0.10 ± 0.28 °C. The new DIAL system is, therefore, capable of performing highly accurate vertical CO2 concentration and atmospheric temperature measurements. We also conducted some continuous observations of CO2 concentration and temperature profiles in the lower atmosphere. In this paper, daily variation of CO2 concentration and temperature profiles are reported. We found that the accuracy of the CO2 concentration profiles measured with the new DIAL is improved significantly by the air temperature measurement. This work was financially supported by the System Development Program for Advanced Measurement and Analysis of the Japan Science and Technology Agency.

A lidar for DIAL measuring the vertical distribution of ozone at the wavelengths 299/341 nm and 308/353 nm is presented. The wavelengths used allow monitoring of vertical stratification of ozone within the upper troposphere - stratosphere. The results of lidar ozone sensing are given in comparison with the IASI/MetOp and MLS/AURA satellites. The results of comparison of the reconstructed profiles of the vertical distribution of ozone with allowance for temperature and aerosol correction confirm the prospects of using the complex of the ozone probing wavelengths of 299/341 nm and 308/353 nm. The results of the comparison show a high accuracy of ozone concentration measurements in the altitude range of 5 to 45 km.

In a wide range of actively developing lidar technologies, the class of biaxial continuous-wave lidars, sometimes called imaging lidars, is moving forward as one of the promising alternatives to traditional pulsed lidars. It combines the triangulation principle applied to CW lidars with spatially-resolved measurements and modern photonic technologies using diode lasers and image processing based on matrix or linear-array detectors.

To ensure undistorted reception and further processing of echo-signals and images as well as reliable restoration of the range profiles of the atmospheric parameters under conditions of intense background radiation of the daytime sky, it is especially important to take into account the specific originality of imaging lidars, which distinguishes this class of instruments from traditional systems. These are the specific features of their spatial selectivity formation based on a reasonable choice of both lidar instrument and array detector parameters, the exposure conditions and physical properties of the background radiation with proper consideration of the propagation medium, etc.

The performed analysis of the imaging lidar focuses attention on the distorting effect of the uneven power of external background coming to single micro-cells of the 1D- or 2D-arrays. In a number of atmospheric-optical situations and with wide variations of optical and design parameters of lidar, there may be noticeable limitations in the measurement accuracy of echo-signals caused by incorrect consideration of the inhomogeneous background load of detector cells and subsequent distortion of results of the atmospheric range profiles retrieval. The approach proposed is aimed at paying attention and overcoming some of these limitations.

This study presents an overview of the recently results obtained by a novel concept of a lidar to remotely monitor methane and volatile organic compound including aerosols and fugitive gas emissions from pipelines, waste disposal areas and tankages. The system works based on Raman and fluorescence scattering principles by emission of a 355 nm beam (3rd Nd:YAG harmonic) and detection of the wavelengths at 355 nm (elastic), 353 nm (oxygen + nitrogen rotational Raman) and 396 nm (methane vibrational Raman) and alternatively the system can be switched to a uorescence lidar based on a 32-channel PMT coupled to an spectrometer to be able to observe fluorescence scattering caused by VOC's and aerosols. This paper shows a summary of the results obtained in the preliminary campaigns, which were carried out under different conditions to be adopted as benchmark for the system performance regarding detection limits, calibration capabilities, and time vs range resolution, in order to optimize the system performance.

Hydrogen explosion on Fukushima No.1 nuclear power plant caused huge damage in real life. Especially its radiation damage caused widespread. Field works on intermediate storages and reuses of decontaminated soils has been started in earnest under government promotion since 2017. This study put a compact polarization lidar at the intermediate storage site, where was only 3 kilometers away from Fukushima No.1 plant. There was a difficult-to-return zone. The lidar system was remotely controlled at Chiba univ. Its observation range was 300m. It covered almost the whole of working field. The lidar monitoring was conducted at one month during Nov. and Dec. in 2017. The lidar scanned horizontally by crossing the dropping port of the decontaminated soils and capturing the suspended dusts on the soil preparation. The lidar monitoring was synchronized with 3 dust-samplers, and we obtained spatial distributions of dust density and estimated the distribution of the radioactivity concentration. The lidar counting rate for dust and the radioactivity concentration was estimated 0.001 mg/m³ /count and 10^-9 – 10^-10 Bq/cm³ , respectively. This estimation was much lower than the working rule of safety assessment of 10^-5 Bq/cm³ . The expressions of these distributions are helpful as communication tool to civilians’ safe and workers’ secure.

In this paper, we show application examples of united generalized methodology for lidar assessment, which uses the dimensionless-parameterization as a core component. It is based on a series of our previous works where the problem of universal parameterization over many lidar technologies were described and analyzed from different points of view. The dimensionless parameterization concept applied to micro-lidars allowed predicting the performance of lidars with SiPMbased receivers as very promising ones.

In micro-lidars, because of high sensitivity to the sky background due to a limited energy of laser emitter, there is an obvious need to analyze the micro-lidar limitations in order to formulate requirements and provide conditions for most effective applications. In order to simplify the micro-lidar capabilities prediction when using SiPMs as echo-signal detectors, and to improve its clarity, we use specific ways to generalize optical, energy and excess-noise parameters inherent to remote sensing tasks, taking into account their possible variability. By normalizing all essential sources of noise to the reference signal inherent in a particular lidar in order to simplify the analytical model, we traced the patterns of the signal-to-noise ratio (SNR) degradation, of increasing threshold sensitivity to “optical weather”, and decreasing the lidar operation range.

To apply the formalism to UV-, Vis- and NIR limited-energy-lidars and to perform the analysis of SiPMs as promising photodetectors for these spectral regions, we utilized a set of specific characteristics that are built from an envelope of dimensionless optical weather conditions and individual detector parameters. On this basis, the analysis of lidar system performance under intense background conditions is developed, and practical recommendations on detector use are given. The dimensionless formalization and the spectral-noise model of the micro-lidar, used as an actual example, allow this approach to be applied to a wide range of lidar detectors operating in a variety of relations between echo-signals and different sources of noise.

The spectroscopic filter plays a critical role in an HSRL (high-spectral-resolution lidar) system. In this paper, a pressuretuned field-widened Michelson interferometer (PT FWMI for short) is proposed. The design of the pressure tuning and the field widening of the PT FWMI are addressed in detail, and the development of a laboratory demonstrator is described as well. The optical elements contain a solid arm made of the glass H-ZF52 with the dimension of 59.572 mm, and an air gap with the length of 32.889 mm within the sealed chamber of 1 atm. Due to the matched dimensions and refractive indices of the two arms, the experimental testing results show that the OPD variation of the developed PT FWMI is about 0.13 lambda and the RMS is less than 0.03 lambda when the divergent angle is as much as 3 degree (half angle). The filtering performance of the prototype developed is scanned with a frequency tunable laser whose bandwidth is 10MHz. Results revealed that bright to dark fringe contrast of the spectroscopic filter is approximately 33. In conclusion, this newly proposed pressure tuning design is suitable for developing stable and tunable FWMI spectroscopic filters and paves the way for designing a robust near infrared HSRL system.

The optical tracking system mainly encounters the problems of sensor delay and external physical disturbance. We propose a method combining Smith predictor and disturbance observer based on Micro-Electro-Mechanical System (MEMS) gyroscope to improve velocity closed-loop bandwidth and disturbance suppression ability. The experimental results demonstrate that the velocity closed-loop bandwidth is increased by about 10 Hz and the disturbance suppression ability is increased by about 11 dB in the low and middle frequency domain.

The results of lidar sensing of the atmosphere in the continent-ocean transition zone obtained on three modifications of a femtosecond lidar: elastic scattering lidar, Raman lidar, white light lidar are discussed. In the mode of multi-frequency sensing (supercontinuum from the fundamental harmonic), the emission lines of the first positive system of the nitrogen molecule are registered. Comparisons of obtained data with the results of lidar sensing using of nanosecond laser pulses are presented.

We test the technique developed for lidar sounding of trace atmospheric gases, which combines the advantages of differential absorption and differential optical absorption spectroscopy methods. We performed numerical experiments in order to estimate the capability of remote atmospheric sounding using a laser system with optical parametric generation in the spectral regions 1.8–2.5 and 3–4 μm. On the basis of this technique, we have found and selected certain wavelengths informative for the gas analysis and simulated lidar signals, the analysis of which showed a possibility of remote monitoring of HCN and C₂H₆ at 1-km horizontal paths, CH₄, at 5-km horizontal paths in the mid-IR, and CO₂ and H₂O at 5-km horizontal paths in the near-IR.

Wind profiler based on continuous laser source is considers in this work. This lidar allows to measure wind profile up to 300 m altitude. Hardware level signal processing technic is developed by JSC «BANS». Increasing accuracy and speed of wind parameters calculation signal processing technics have been studied in this research. The practice results are presented.

We focused on the propagation property of an annular beam in strong scattering random media such as nimbostratus or dense fog. An annular beam as a lidar transmitted beam can propagate a longer distance even through atmospheric fluctuation. The reason is that an annular beam can self-transform to a non-diffracting beam, which is called non-diffractive effect. In this work, the center peak intensity as result of non-diffractive effect was generated after the propagation of an annular beam in random media with different concentrations and propagation distances. The linear relationship between the propagation distance and the transport mean free path calculated from the media concentration that caused the maximum center peak intensity was obtained. The generation condition of the non-diffractive beam was discussed under arbitrary parameters of beam diameter, propagation distance and media concentration.