Dr. Toshihiro Somekawa, Researcher

Dr. Toshihiro Somekawa

Development of the White Light Lidar using a High Power Femtosecond Laser System

Institute for Laser Technology

*The organization and the title are those when awarded

Abstract

  • 日本語
  • English

高強度フェムト秒レーザーを希ガスに集光すると,紫外から赤外におよぶ超広帯域なスペクトルを有するコヒーレント白色光が生成される。この白色光を,レーザーレーダー(ライダー)の光源として用いる白色光ライダーの開発を行っている。白色光ライダーでは,散乱の波長依存性を利用したエアロゾルの粒径分布の推定や,偏光特性を利用した,黄砂の形状による識別,赤外域を利用した温室効果ガスである二酸化炭素の観測といった環境計測を同時に行うことができ,1台のライダーシステムで多種多様な環境計測が期待できる。

A white light lidar system, which uses self-trapping of the intense femtosecond laser pulse in atmosphericpressure Kr gas, was utilized to obtain multi-wavelength backscatter and depolarization profi les from aerosols and clouds. The white light lidar has the advantage of performing at an arbitrary wavelength that is independent of the laser source. The observed results provided the wavelength dependence to enable the multi-wavelength depolarization ratio to be used as a method to evaluate the size of the atmospheric aerosols without using conventional inversion algorithms. As an environmental measurement example from the white light lidar, the Asian dust profi les were obtained by the white light depolarization system. The white light lidar system provides the new perspectives in a large number of fi elds such as the remote detection of the Asian dust particles that pose a threat to cross-border pollution in Japan or the monitoring of green house gases.

Research summary

Dr. Somekawa’s research applied ultra-short plus laser technology to the remote measurement of air quality.

His work demonstrates the potential to environmentally monitor a wide variety of species over very large areas.

Dr. Somekawa specifically developed a compact white light detection and ranging (lidar) spurce that enables practical remote sensing of the environment.

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