椎名 達雄

Abstract. A horizontally pointing lidar is planned for deployment with other instruments in Fukushima, Japan, to continuously monitor and characterize the optical properties of radioactive aerosols and dust in an uninhabited area. Prior to installation, the performance of the lidar is tested at Chiba University. Data from the continuous operation of the lidar from August 2021 to February 2022 are analyzed for extinction and depolarization ratio. These are compared with the weather sensor and particulate matter (PM2.5) measurements to quantify the relationship between atmospheric conditions and optical properties of near-ground aerosols. The results show that lidar data’s extinction coefficient and depolarization ratio can have a quantifiable relationship with relative humidity (RH), absolute humidity, rain rate, wind speed, wind direction, and PM2.5 concentration. Analysis of the seven-month data shows that the optical properties of aerosol and dust depend on the combined effects of the weather parameters. An increase in RH or PM2.5 concentration does not imply an increase in radioactive aerosols. The average extinction coefficient and depolarization ratio of aerosols and dust originating from the land and ocean show different values and opposing trends which can aid in determining the occurrence of ground-based radioactive dust and aerosols. The information obtained from analyzing the interrelationship among lidar, weather parameters, and PM2.5 concentration is essential in assessing the occurrence of radioactive aerosols and characterizing local aerosol-weather relationships in a radioactive area. This result provides essential information in describing radioactive aerosols in Fukushima.

Abstract Visualization of dust flow and wind dynamics near the ground surface are essential for understanding the mixing and interaction between geosphere and atmosphere near the surface. Knowing the temporal dust flow is beneficial in dealing with air pollution and health issues. Dust flows near the ground surface are difficult to monitor because of their small temporal and spatial scale. In this study, we propose a low-coherence Doppler lidar (LCDL) for measuring dust flow near the ground with high temporal and spatial resolutions of 5 ms and 1 m, respectively. We demonstrate the performance of LCDL in laboratory experiments using flour and calcium carbonate particles released into the wind tunnel. LCDL experiment results show a good agreement with anemometer measurement in wind speeds ranging from 0 to 5 m/s. The LCDL technique can reveal dust’s speed distribution, which is affected by mass and particle size. As a result, different speed distribution profiles can be used to determine dust type. The simulation results of dust flow coincide well with the experimental results.

An optical coherence tomography (OCT) system based on the ghost imaging (GI) technique is developed for correctly imaging in scattering media. Usually, the scattering in the media leads to a decrease in the signal-to-noise ratio of the reconstructed image. This problem can be solved by using ghost imaging-OCT(GI-OCT), but the number of patterns required for GI reconstruction depends on the concentration of the scattering media. Therefore, studying the relationship between the intensity distribution in reconstructed images and the optical properties of scattering media is essential. In this study, image reconstruction is carried out in scattering media with a concentration of 0.0% to 1.4%, diluted from processed milk. Using the structural similarity index method (SSIM) to analyze the reconstruction condition, it is found that the target image can be reconstructed correctly when the SSIM value is more than 0.7. By analyzing the intensity distribution of the reconstructed image, the results show that the extinction coefficient of the scattering media is negatively correlated with the contrast of the reconstructed image and positively correlated with the scattering intensity. Their correlation coefficients are −0.94 and 0.99, respectively.

The real-time chlorophyll-a pigment monitoring of C. reinhardtii is studied using our developed LED fluorescence light detection and ranging (LiDAR) system. It features a portable set-up that uses a pulsed LED module with an excitation wavelength of 385 nm. We were able to monitor the different growth phases of C. reinhardtii with specific cultivation parameters. The developed fluorescence LiDAR system showed the linear correlation of its chlorophyll-a signal with the optical density and EEM fluorescence measurements at 680 nm emission wavelength. Water quality and weather parameters were also measured, which explains the variation in the growth dynamics of C. reinhardtii during the sampling period. The results from the monitoring demonstrated a different technique that can be used in estimating algal biomass in the environment.

LED (light-emitting diode)-lidar (light detection and ranging) has gradually been focused on by researchers because of its characteristics of low power, high stability, and safety to human eyes. However, LED-lidar systems are easily disturbed by background light noise. Echo signal denoising is an essential work that directly affects the measurement accuracy of the LED-lidar system. The traditional variational modal decomposition (VMD) method in lidar signal denoising relies on practical experience to optimize the critical parameters of quadratic penalty factor α and the number of intrinsic mode function (IMF) components K globally, which is hard to denoise effectively. For this problem, a denoising method based on VMD with the adaptive weighted particle swarm optimization (PSO) is proposed in this work. The PSO-VMD method adaptively adjusts the weight value ω for different lidar echo signals and optimizes of the parameters α and K globally. The LED-lidar echo signals are denoised by moving average, VMD, and PSO-VMD. Using the denoised echo signals, the range compensation waveforms and the extinction coefficients are derived. The results show that the PSO-VMD denoised echo signal has the highest R-square value of 0.9972 and the minimum standard deviation value of 5.7369, while the values of r-square and standard deviation of the echo signal denoised by moving average and VMD method are 0.9902, 9.7450, 0.9945, and 7.3588, respectively. The derived distance compensation waveforms and extinction coefficients based on the PSO-VMD denoising have better stability than those based on the moving average and VMD denoising.

When the conventional optical coherence tomography (OCT) measures the transmittance and the absorbance of the target in the scattering media, its image is affected by the scattering media and gets a modulated target profile. Due to the influence of scattering and absorption by the media, the conventional OCT cannot eliminate this modulation. By using our proposed idea, ghost imaging-OCT (GI-OCT), to apply the GI technique to the measurement path of OCT, we can reconstruct the target profile in the scattering media without modulation. In this work, we introduce and demonstrate the concept and the experimental method of GI-OCT. This application can correct the influence of the scattering media for the target optical profile due to the advantage of the GI technique, which suppresses noise, here, modulated by scattering. Comparing the experimental results of the corrected target image with the original target image, we obtain the same distributions in the binarized images, and the error of the character size in the binarized deconvoluted image is less than the resolution of the image (0.04 mm), proving that the method successfully reconstructs the image without the scattering media influence.

The propagation methods of a non-diffractive beam (NDB) for optical sensing in scattering media have been extensively studied. However, those methods can realize the high resolution and long depth of focus in the viewpoint of microscopic imaging. In this study, we focus on macroscopic sensing in living tissues with a depth of a few tens centimeters. An experimental approach for generating adequate NDB in dense scattering media based on the linear relationship between propagation distance and transport mean free path is reported. For annular beams with different diameters, the same changes of the center intensity ratio of NDB are obtained from the experiment results. They are discussed with theoretical analysis. As a result, the maximum center intensity ratio of the adequate generated NDB can be estimated at arbitrary propagation distance in the dense scattering media.

A non-invasive and simple point measurement using a portable TD-OCT system was used to measure the leaf structure and attenuation coefficient of healthy and unhealthy leaves of a Citrofortunella Microcarpa plant. Assuming homogeneity within the layers, the attenuation coefficient was obtained by linear fitting the logarithm of the A-scan or depth profile of the leaf. The attenuation coefficients of the epidermal and palisade layers of the healthy leaves were 27.07/mm and 15.36/mm, respectively, and for the unhealthy leaves they were 21.82/mm and 8.01/mm, respectively. Comparing the A-scan profiles obtained for the healthy and unhealthy leaves, a mixing of the epidermal and palisade layers within the unhealthy leaves was observed. These observations and the decrease in the attenuation coefficients of the unhealthy leaves are indications of deterioration in the photosynthetic rate that enhances the growth and development of the plants which can provide early detection of sickness benefitting Filipino farmers.

Chlorophyll-a measurement is important in algal growth and water quality monitoring in natural waters. A portable pulsed LED fluorescence lidar system based on the preliminary algal organic matter and pigments excitation–emission matrix (EEM) of commercialized AZTEC Spirulina powder at varying concentrations was developed. Fluorescence peaks from EEMs showed increasing intensity as the Spirulina concentration increases. Using this information, an LED fluorescence lidar with a wavelength of 385 nm, pulse width of 10 ns, and repetition frequency of 500 kHz was constructed for chlorophyll detection at 680 nm. Turbidity measurements were also conducted at 700 nm emission wavelength at the same excitation wavelength. Range-resolved fluorescence lidar signals from the portable pulsed LED fluorescence lidar system are highly correlated with the standard methods such as optical density at 680 nm (R2 = 0.87), EEM fluorescence chlorophyll-a pigment at 680 nm (R2 = 0.89), and corrected chlorophyll-a concentration (R2 =0.92). The F680/F700 lidar ratio was measured to provide a linear relationship of chlorophyll-a and turbidity in waters. The F680/F700 measurement showed strong correlations with Spirulina concentration (R2 = 0.94), absorbance at 680 nm (R2 = 0.84), EEM chlorophyll-a pigment at 680 nm (R2 = 0.83), and corrected chlorophyll-a concentration (R2 = 0.86). Results revealed that this new technique of chlorophyll-a measurement can be used as an alternative to other standard methods in algal growth monitoring.

In recent years, with the development of precise lathe-cutting equipment, special shaped contact lenses (CL) have been crafted. However, while it is possible to manufacture such a lens, its shape evaluation has not been well-established. We conducted a basic optical experiment using special lenses to measure a spherical lens and nonspherical mold. As the measurement sample, a metal ball, special CL, and a toric-shaped mold were adopted. In order to accurately measure those real shapes, we proposed an algorithm in which the probe light is vertically incident to the sample surface within a numerical aperture of the optical probe. For this algorithm, we developed the specialized time-domain optical coherence tomography (TD-OCT), which was designed to conduct circular scanning while maintaining vertical incidence by driving a two-axis (vertical and horizontal) micro-electromechanical system mirror with a phase difference of 90°. The shape, thickness distribution, and curvature radii of both front and back surfaces of a CL were estimated with this OCT signal analysis and sphere fitting. The shape and curvature radius were evaluated by using the simulated data under the same experimental conditions. They were sufficiently accurate based on the resolution of this OCT. Also, a toric-shaped mold was evaluated by comparing the relationship between each coordinate and intensity of the interference signal. As a result, it is confirmed that the experimental result and the simulated matched well.

The 2D and 3D measurement algorithms for real front and back curved surfaces of contact lenses (CL) were developed. The purpose of 2D algorithm is to evaluate spherical lenses. We adopted the algorithm to be incident the probe light vertically along the curved surfaces of CLs under the condition that the difference of curvature radii between the front and back surfaces is small enough within numerical aperture (N.A.) of the optical probe. The vertical incidence against the curved surface is judged by using the intensity balance between OCT interference signals from both front and back surfaces of CL. As a result, the lens shape matched with the design value and RMSE of the thickness was 5.33 μm. Also, regarding the curvature radii, compatibility between this OCT device and the conventional device was indicated. In the 3D algorithm, we conducted a basic experiment using some special lenses in order to develop non-cylindrical lens measurement. By moving a 2-axis (vertical and horizontal) Micro Electro Mechanical System (MEMS) mirror with phase difference of 90°, it was designed to conduct circular scanning while maintaining vertical incidence of probe beam on the front surface of CL. The shape and the curvature radius was evaluated with simulation data under the same conditions. As a result, although it has an error against the design value, the result and the simulation result matched well.

The attenuation of backscattered light through human tissue makes it difficult to measure the interferometric signal with high accuracy. We present a new method that combines the originally developed Time Domain-OCT (TD-OCT) technique with Ghost Imaging (GI) technique to detect targets at a certain depth in the scattering medium. Our method's first result shows that sample images can be reconstructed through a homogeneous mixture of 0.5% milk solution (1 cm thickness) scattering medium. Theoretical calculations show that it is possible to reconstruct images in higher milk solutions (about 20%) with optical properties close to human tissues.

Nighttime clouds are detected using a camera without a NIR-cut filter by exploring the pixel value distribution in each red, green, and blue (RGB) color space from clear and 100% cloudy sky images. The removal of the NIR-cut filter enhances the pixel values of each color space due to the additional NIR signals. Cloud pixels can be separated from clear sky pixels by only using each color space and applying the appropriate threshold. Exploring different cloud detection methods is vital in our ongoing research activity collecting clear and cloudy sky images in other countries using this camera.

In this work, we propose a low-coherence Doppler lidar (LCDL) to measure particle velocity at near-surface atmosphere. To measure particle velocity information at near-surface atmosphere, it is necessary to conduct the measurement at high frequency and resolution. Low coherence light source can satisfy this high-resolution criterion. We discuss the system efficiency to detect atmospheric echoes by theoretical analysis. In the particle velocity experiment, Doppler shifted frequency is about 5 MHz and the particle velocity calculated from the peak Doppler signal is 2.7 m/s, while minimum and maximum velocity are 1.85 and 2.92 m/s, respectively. Anemometer result shows good agreement with LCDL results.

The optical measurement algorithm for the real front and back surfaces of contact lenses from their center to periphery accurately and simultaneously is proposed. It is an algorithm that makes light incident vertically along the curved surfaces of contact lenses under the condition that the difference of curvature radii between the front and back surfaces is small enough within the NA of the optical probe. For this purpose, we adopted time-domain optical coherence tomography (OCT) with translation and rotation mechanisms. The shape, thickness distribution, and curvature radii of both surfaces were estimated with OCT signal analysis and circular approximation. The measured results were compared with the designed values and the measured data from a conventional shape measurement device. The curved shape of both surfaces and thickness were well matched with the designed values from lens center to periphery. In a curvature radius of the front surface, there was a proportional bias with a limit of agreement of to , and the correlation coefficient was 0.57. On the back surface, there was no systematic bias, and minimal detectable change was 0.178 mm, in a range of 95% confidential interval. The proposed algorithm well visualized the real shape and optical characteristics of the contact lens with enough accuracy to the design.

Aerosol optical properties are measured near the surface level using sampling instruments and a near-horizontal lidar. The values of the aerosol extinction coefficient inside the instruments are derived from nephelometer and aethalometer data, while the ambient values are measured from the lidar. The information on aerosol size distribution from optical particle counters is used to simulate extinction coefficients using the Mie scattering theory, with corrections on the humidity growth of hygroscopic particles. By applying this method to the continuous data obtained from November to December 2018 at Chiba, Japan, we elucidate the temporal variations of near-surface aerosol properties, including the complex refractive index, single scattering albedo, and Angstrom exponent. The results indicate how aerosol particles change their properties between the dry, instrumental conditions and relatively humid setting of the ambient atmosphere.

Laser beam propagation in highly random media can potentially be applied to various optical studies, though the light penetration is often limited to the surface or skin regions of the targets. In free space, it is known that the use of a non-diffractive beam (Bessel beam) is useful for achieving a long-distance propagation by reducing the influence of diffraction. In our previous work [Z. Peng, and T. Shiina, Opt. Commun. 391, 94-99 (2017)], the generation and propagation of such a non-diffractive beam were studied in a scattering medium of colloidal suspension (diluted milk) up to the concentration of 1.2% using cell lengths between 10 and 30 cm. The transformation from an annular beam to a non-diffractive beam was observed using a detector with a narrow view angle of 5.5 mrad. In the present study, experimental results are reported for much higher concentrations using shorter cell lengths of 3 and 5 cm. It is found that a non-diffractive beam is generated as a central peak superposed on widely distributed intensity due to multiple scattering. The polarization property is preserved during the transformation from annular ring to central peak. M the propagation distance of 3 cm, the intensity of non-diffractive beam is maximized with a high media concentration of 22.0% which yields the scattering coefficient of 5 cm(-)(1). Furthermore, it is found that the media concentration range that leads to the generation of the non-diffractive beam becomes wider for such shorter propagation distances.

Studying near-surface aerosol properties is of importance for a better assessment of the aerosol effect on radiative forcing. We employ the data from a near-horizontal lidar to investigate the diurnal behavior of aerosol extinction and single scattering albedo (SSA) at 349 nm. The response of these parameters to ambient relative humidity (RH) is examined for the data from a one-month campaign conducted in Chiba, Japan, during November 2017, a transition period from fall to winter. The Klett method and adaptive slope method are used in deriving the aerosol extinction coefficient from the lidar data, while the SSA values are retrieved using an aethalometer. Also, a visibility-meter is used to examine the aerosol loading inside the atmospheric boundary layer. It is found that the aerosol growth during the deliquescence phase is more readily observed than the contraction in the efflorescence phase. The decrease of SSA before the deliquescence RH is found for approximately 46% of the deliquescence cases, presumably representing the particle shrinkage of soot particles.

We have developed a method to evaluate absolute value of return loss from crack on an optical fiber in an optical connector by using the specialized TD-OCT. The absolute measurement of the return loss could be accomplished in the range of -10 to -100 dB with an error of +/- 3 dB. As a result, the micro crack of the optical fiber could be evaluated quantitatively. Furthermore, the state of the micro crack, which could not be detected in the past, was able to be analyzed without taking the product apart. If the value of the return loss and the elapsed time from its manufacturing are known, the angle of micro crack of the optical fiber and presence or absence of the gap between the fracture endfaces can be estimated.

The creation of a compact and easy-to-use atmospheric lidar has been the aim of researchers for a long time. Micro Pulse Lidars (MPL) and commercialized ceilometers were designed for such purposes. Laser Diodes (LD) and Diode-Pumped Solid State (DPSS) Laser technology has evolved, making lidar system more compact; however, their vulnerability to static electricity and fluctuation of electrical power prevented the growth of atmospheric lidar technology as a system suited to all kinds of users. In this study, a mini lidar with a Light Emitting Diode (LED)-based light source was designed and developed. As LED lamp modules do not need a heat sink or fan, they are resilient and can emit light for long periods with constant intensity. They also offer ease of handling for non-professionals. On the other hand, a LED lamp module has a large divergence, when compared to laser beams. A prototype LED mini lidar was thus developed, with focus on transmitting power optimization and optical design. This low-cost lidar system is not only compact, but also offers near-range measurement applications. It visualizes rapid activities of small air cells in a close range (surface atmosphere), and can verify and predict the condition of the surface atmosphere. This paper summarizes the principle, design, practical use and applications of the LED mini-lidar.

When an annular beam is used as a lidar transmitting beam in the atmosphere, it can make the influence of the atmosphere fluctuation smaller than a Gaussian beam, because the annular beam can self-transform to a non-diffractive beam. However, in general, light is hard to propagate at long distance in random media, such as cloud or haze, due to strong scattering of particles. In this paper, the annular beam (diameter: 40 mm) was propagated in random media (diluted processed milk, milk fat: 1.8%) and the propagated waveform was detected by a narrow view angle of 5.5 mrad. The nondiffractive beam was successfully generated at the short distance of 3 cm ~ 5 cm in random media with high media concentration of 2% ~ 23%. It was generated in wider concentration range at shorter distance in random media with higher concentration. Furthermore, the relation between concentrations and transmittance value under the generation range of non-diffractive beam was discussed.

When change over time of hydrogen gas concentration in a certain point is measured, a gas sensor is fixed at the measurement point, or a syringe is utilized to sample the gas, which is analyzed by gas chromatography. However, the gas sensor and the syringe have an influence on gas flow and its measurement. Non-contact measurement technology with high temporal resolution and high spatial resolution is necessary. Therefore, in this study, for the purpose of non-contact measurement of the hydrogen gas concentration in the small area under the gas flow, a specialized experimental device was developed. A laser beam (wavelength 355 nm, pulse energy 120 μJ, PRF 1 kHz) with the beam diameter 1 mmφ at the measurement spot was irradiated to the hydrogen gas. Raman scattering light at the measurement point of 750 mm ahead was focused by Fresnel lens, which is arranged at the orthogonal direction against the transmitting laser beam. As a result, it was proved that Raman signal intensity had good linear correlation with hydrogen density of more than 100ppm. The gas concentration in a small area could be quantitatively estimated without interference of the gas flow.

Beam propagation has been given important attention in a variety of applications in medicine, remote sensing and information science. Especially, the beam propagation in highly scattering media, which is called random media, is important. In general, the multiple scattering gets rid of beam characteristics, e.g., intensity distribution, phase front, and polarization. In this study, self-converging effect of annular beam was applied in random media. Diluted milk was used as random media, and the transmitted light was detected with a narrow view angle of 5.5mrad. The collimated annular beam of a few tens millimeters takes a few hundred meters to transform its beam shape into the non-diffractive beam in free space, while this transformation was shorten only to 20 cm in random media, that is, the collimated annular beam caused its transformation at only 20 cm in random media. The transformed beam kept its optical characteristics of "non-diffractive beam". Such transformation of the annular beam needs the appropriate condition of random media. Media concentration and propagation distance control the generation of the center peak intensity of the transformed beam. This study indicates the generation of the non-diffractive beam in random media and reveals its appropriate condition.

We researched and demonstrated two-dimensional (2-D) deflectors constructed by on-axis type acousto-optic deflectors (AOD) in order to attain a multibeam recording for an internal drum scanning exposure system. First, we researched an on-axis AOD using anisotropic Bragg diffraction to obtain high diffraction efficiency. A significant improvement of diffraction efficiency was observed when acoustic waves are travelling in the [110] axis of paratellurite (TeO2) crystal, an incident light of linear polarization is traveling into a TeO2 along the [001] optic axis, the crystal is rotated about the [110] axis, and furthermore the direction of polarization of incident light is adjusted to the eigenmode of a TeO2 crystal. Second, we configured 2-D deflectors by cascading two AODs and achieved the multibeam laser recording for the internal drum scanning exposure system. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)

Soft X-ray projection microscopy has been developed for high magnified imaging of hydrated biological specimens because water window region is available. The projection microscopy is a simple optical layout and has advantages over other types of microscopes particularly for biological specimens because of its wide viewing area, easy zooming function and easy extension to CT. However the projection image is blurred by the diffraction of X-rays, resulting in the deterioration of the spatial resolution. In this study, the blurred images have been corrected by an iteration procedure, i.e., Fresnel and inverse Fresnel transformations are repeated. The correction was found to be not effective for every image, especially for images with low contrast. A contrast enhancement method prior to the iteration procedure was installed to make the iteration procedure more effective, but it was not enough yet due to the influence of background noise. We evaluated dependency between the background noise level and iteration effect in the cases with or without the contrast enhancement prior to the iteration procedure by simulation. We also demonstrated upper limits of the background noises which chromosome images are effectively corrected by the iteration procedure.

Light is quite difficult to propagate a long distance in random media such as human tissue or atmospheric dense cloud because of its scattering and absorption. For optical sensing, it is important to increase propagation efficiency which means expanding the sensing range. An annular beam can transform its waveform into a non-diffractive beam due to its propagation in a long distance. In our previous work, we found the annular beam also had non-diffractive effect when it propagated in diluted milk solution of a few tens centimetres at the concentration of less than 1%. In this study, to clear up how to control and optimize the non-diffractive effect of the annular beam in random media, numerical calculation of propagation characteristics of annular beam in air was estimated. The narrow annular beam with a small diameter would generate a high intensity non-diffractive beam at a short distance. We also had three sets of experiments of annular beam propagation in random media with the same view point as the calculation, but its propagation characteristics was evaluated by milk concentration. They showed the same variation of a non-diffractive beam with the result of numerical calculation in air. These results provide us a hint of optimization for annular beam propagation in random media.

A mini-lidar to observe the activity of Martian atmosphere is developed. The 10cm-cube LED mini-lidar was designed to be onboard a Mars rover. The light source of the mini-lidar is a high powered LED of 385nm. LED was adopted as light source because of its toughness against circumference change and physical shock for launch. The pulsed power and the pulse repetition frequency of LED beam were designed as 0.75W (=7.5nJ/l0ns) and 500kHz, respectively. Lidar echoes were caught by the specially designed Cassegrain telescope, which has the shorter telescope tube than the usual to meet the 10cm-cube size limit. The high-speed photon counter was developed to pursue to the pulse repetition frequency of the LED light. The measurement range is no shorter than 30m depending back-ground condition. Its spatial resolution was improved as 0.15m (=ins) by this photon counter. The demonstrative experiment was conducted at large wind tunnel facility of Japan Meteorological Agency. The measurement target was smoke of glycerin particles. The smoke was flowed in the wind tunnel with wind speed of 0 - 5m. Smoke diffusion and its propagation due to the wind flow were observed by the LED mini-lidar. This result suggests that the developed lidar can pursue the structure and the motion of dust devil of >2m.

There are large demands to monitor the atmosphere in the closed space (hall, factory and so on), to check vegetation remotely and to detect hazardous gases such as explosive gas and bio terror from explosion-proof distance. On the contrary, traditional lidars have blind area, it is hard to monitor the atmosphere and the gas in the near range. In this study, optical designs and concrete developments for the atmosphere monitoring and the certain gas detection in near range were accomplished. Unique optical designs are introduced and their practical setups are explained.

Lidar is a powerful remote sensing tool to monitor the weather changes and the environmental issues. This technique should not been restricted in those fields. In this study, the authors aim to be apply it to the prediction of weather disaster. The heavy rain and the lightning strike are our targets. The inline typed MPL (micro pulse lidar) has been accomplished to grasp the interaction between the low altitude cloud and the atmosphere and to predict the heavy rain, while it was hard to catch the sign of lightning strike. The authors introduced a new algorism to catch the direct sign of the lightning strike. Faraday effect is caused by lightning discharge in the ionized atmosphere. This effect interacts with the polarization of the propagating beam, that is, the polarization plane is rotated by the effect. In this study, high precision polarization lidar was developed to grasp the small rotation angle of the polarization of the propagating beam. In this report, the interaction between the low altitude cloud and the atmosphere was monitored by the high precision polarization lidar. And the observation result of the lightning discharge were analyzed.

For the optical sensing in random media, an annular beam was used because of its nondiffractive feature. In our previous work, we have confirmed the nondiffractive effect of the annular beam in diluted solution of milk as random media. In the experiment of this study, increment of the nondiffractive effect has been confirmed by using the pulsed annular beam. We have simulated propagation characteristics of the annular beam in random media by wave analysis method. The attenuation rate and the forward scattering pattern of the propagation beam were calculated, and it showed agreement by comparing them with results of the experiment. © 2011 SPIE-OSA-IEEE.