Fumitoshi Kobayashi

Sodium temperature lidar based on injection seeded Nd:YAG pulse lasers using a sum-frequency generation technique

We report on a sodium (Na) temperature lidar based on two injection seeded Nd:YAG pulse lasers using single-pass sum-frequency generation. The laser power at 589 nm is 400 mW (40 mJ per pulse at a repetition rate of 10 Hz) and the pulse width is 22 nsec FWHM. The narrowband laser tuned to the Doppler broadened Na D2 spectrum enables us to measure the temperature of the mesopause region (80-115 km). This solid-state transportable system demonstrated high performance and capability at Syowa Station in Antarctica for 3 years and at Uji in Japan for an additional year without any major operational troubles.

Laser-induced fluorescence imaging of plants using a liquid crystal tunable filter and charge coupled device imaging camera

We developed a laser-induced fluorescence imaging system for plant monitoring use, with which it was possible to make an image at any wavelength between 430 and 750nm. The excitation source for the fluorescence was a cw ultraviolet laser diode with 398nm, and the detector was an image-intensified charge coupled device. A liquid crystal tunable filter was used as the fluorescence wavelength selection device. All of the system performance including the wavelength tuning was electrically controlled, so that it could be operated with no mechanical vibration noise. The fluorescence images of a coffee tree leaf obtained at 440, 530, 685, and 740nm clearly showed a distribution pattern of the fluorescence intensity over the leaf. The pattern reflected the different physiological statuses of the plant. Advantages of the imaging system were experimentally discussed on a point of detection of inhomogeneous physiological activities over a plant leaf.

Imaging system of solar-induced plant fluorescence for monitoring of plant living status

We developed a practical field-based method of sensing the physiological status of live plants. The potential of detecting solar-induced plant fluorescence, which originates in chlorophyll molecules, through a non-destructive and remote sensing method was investigated. We constructed a plant fluorescence imaging system that adopted the Fraunhofer line discrimination (FLD) method in which the A-line (atmospheric oxygen absorption band of 760.78 nm) was used. The performance of the system was tested using three types of sampled leaves. Fluorescence intensities from their images produced with the system were highly correlated with fluorescence obtained from fluorospectrometer measurements (R2=3D0.95). We were able to produce fluorescence imaging of a redrobin living in field, including leaves, stems and branches. Fluorescence intensity varied with the chlorophyll content of each component.

ON and OFF channels in human retinal ganglion cells

•  The ON and OFF channels are basic functional elements in parallel processing in the visual system in vertebrates including primates, and ON cells excite by positive contrasts, while OFF cells excite by negative contrasts. •  We investigated the electrophysiological properties of optic tract fibre activities in neurosurgical patients with Parkinsons disease, focusing on ON‐ and OFF‐type responses to flashlight stimulation. •  Most of the multi‐fibre responses at the light on event were excitatory, and excitatory responses at the light off event were observed at a few sites. Analysis of the single‐fiber responses revealed ON fibres and OFF fibres. •  All excitatory responses to light on were transient, while all but one excitatory responses to light off were sustained. These different response types are said to contain different modes of visual information. •  Our results demonstrate for the first time the ON and OFF channels and their temporal features in visual processing in humans.

Field Server Monitoring System for Construction of IT Farming and Agri-tourism - Trial Report from Obuse-town, Nagano Japan

A new agricultural farming and management system is proposed, which is based on real time field monitoring of agricultural related information using a Field Server. The Field Server monitoring network system was developed at a vine yard at Obuse-town in Nagano, Japan. Data of environmental condition (solar-radiation, temperature, relative humidity, and soil moisture) and growth information (leaf and branch shapes, blooming, fruiting and size) were automatically collected by the Field Server and transferred to a personal computer inside a house through a wireless LAN which could connect the two places at a distance of about 300 m. These information are used not only for farming, but also for agri-tourism that is one of strategies for the Obuses agricultural industry with sustainable development. Some ideas are also proposed for the data use

Image detection of solar-induced plant fluorescence

A fluorescence imaging system has been developed for detection of plant fluorescence induced by sunlight. A new technique for evaluating unknown solar intensity was introduced to the Fraunhofer line detection. The fluorescence observations were made using plants with different status of growth, and the digital image of the plant fluorescence clearly showed the difference.

Remote Detection of the Fluorescence Spectrum of Natural Pollens Floating in the Atmosphere Using a Laser-Induced-Fluorescence Spectrum (LIFS) Lidar

A mobile laser-induced fluorescence spectrum (LIFS) lidar was developed for monitoring pollens floating in the atmosphere. The fluorescence spectrum of pollens excited at 355 nm was measured with a fluorescence spectrometer and the results suggested that in general they had peaks at around 460 nm and the ranges were 400–600 nm. A fluorescence spectrum database of 25 different pollens was made with the 355 nm excitation. Based on these results, we developed a LIFS lidar that had features in pollen species identification and daytime operation. The former was achieved by the database and the latter was possible by introducing a synchronous-delay detection to a gated CCD spectrometer in an operation time of 200 ns. Fluorescence detection of pollens floating in the atmosphere was performed using the LIFS lidar in a field where cedars grow in the spring and ragweed in the autumn. The LIFS lidar system successfully detected fluorescence spectrums of the pollens at a distance of approximately 20 m away. We discussed the performance of the LIFS lidar by estimating the number of cedar pollens using a lidar equation, introducing a fluorescence cross section of cedar pollens and a sensitivity of the CCD spectrometer that was measured by ourselves.

Sum frequency generation of sodium D2 resonance line for the lidar application of mesopause temperature measurements

Sum frequency generation of sodium D2 resonance radiation (589 nm) based on injection seeded Nd:YAG lasers was applied to a sodium lidar transmitter for temperature measurements of the mesopause region (80-105km). The output energy was 40 mJ / pulse at a repetition rate of 10 Hz and a temporal width of 28 nsec. The laser wavelength at 589 nm (~0.04 pm FWHM) was finely tuned with an accuracy of 0.1pm by seeders. The lidar installed at Syowa station (69°S, 39°E), Antarctica, measured temperature profiles between March and September during 2000 and 2001. Monthly averaged temperature profiles in the mesopause region in wintertime (June, July and August) are nearly 20 K lower than those in the northern hemisphere sites. The measured winter mesopause altitudes (~99 km) are in good agreement with those measured in the northern winter hemisphere. The mesopause temperatures (~175 K) in winter months however are about 20 K lower than those observed from a northern hemisphere conjugate site, Andoya (69°N). The lower winter mesopause temperatures measured at Syowa station, which are consistent with southern hemisphere mesopause temperatures measured by a shipborne lidar, suggest the existence of a hemispheric difference. Possible causes for this difference are discussed.

Observations of atmospheric boundary layer at the inland district capital Nagano with a bistatic imaging lidar

We have developed the bistatic imaging lidar for measuring the lower atmosphere at the daytime as well as at nighttime. The lidar has composed of a transmitting system of a Nd: YAG laser (532nm, 10Hz, and 5OmJ) and a receiving system of a cooled high-sensitive CCD camera with an image intensifier as a high-speed shutter. Vertical profiles could be obtained every one minute and indicated in a real time monitor with color contoured time-height indication. We have been making regularly the 24 hours observations of the atmospheric boundary layer once a week at the inland district capital, Nagano City, closed in by the high mountains since August 1999. Some interested results have been obtained from the temporal and seasonal variations of the boundary layer. We describe the oscillatory rising motion of the top height of the boundary layer in the morning, the diffusion of aerosols due to car fumes during the rush hours both in the morning and in the evening and the downward motion of the cloud base height just before rain or snow. Moreover, it is reported about the difference of boundary layer activities between in summer and in winter under an inland climate.

Daytime Measurements of the Lower Atmosphere with a Bistatic Imaging Lidar

We have developed a bistatic imaging lidar for measuring the lower atmosphere even at daytime. In order to reduce the background noise at daytime, a gated image intensifier has been used as a high speed shutter synchronized with the laser pulses. We discuss its feasibility on the basis of field experiments.