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World’s Most Advanced Spectral Measurement Technology

This article was published in the Spring 2020 edition of Litterae Populi. The full list of articles can be found Here.

Remote sensing with the world’s most advanced spectral measurement technology

The technology for contactless observation of the shape and nature of an object from a remote location is known as remote sensing. When an object is exposed to electromagnetic waves (e.g. visible light, infrared rays, microwaves), some or all of the waves are repelled (reflection). The object itself can also emit electromagnetic waves into space. The properties of electromagnetic waves reflected or emitted by the object under examination depend on the status of the object or on the types of materials that make up the object. Therefore, it is possible to determine the shape and nature of the object by receiving electromagnetic waves reflected or emitted from the object using a sensor on an artificial satellite, airplane or vehicle and analyzing their properties.


Yukihiro Takahashi in his laboratory at the Department of Earth and Planetary Sciences.

While remote sensing is applicable in a wide variety of areas, a particularly important application example is “observing various global environments”. By receiving and analyzing electromagnetic waves reflected or emitted from the surface of the ground, it is possible, for example, to continuously observe sea water temperature and forest areas and to monitor the progress of global warming. Professor Yukihiro Takahashi of the Faculty of Science deals with remote sensing with such properties and uses the world’s most advanced spectral measurement technology. He is concerned with the development of technologies for the growth of agricultural crops and the diagnosis of pests by means of remote sensing.

“I became interested in astronomy when I was reading a Gakushu manga (学習 漫画, comic to study). I made the decision to become an astronomer when I was in third grade of elementary school, ”says Professor Takahashi. After graduating from high school in Chiba Prefecture, he entered Tohoku University. “I decided to go to Tohoku University when I was in junior high school. After entering the university, I became interested in studying the aurors and chose a geophysics laboratory. “He then entered the graduate school of the university and stayed for a year as a member of the wintering party of the Japanese Antarctic Exploration Expedition at Showa Station in Antarctica. There he observed aurors and wrote his thesis based on the data. Professor Takahashi then became a teacher at Tohoku University and came across a research topic that motivated him to get involved in the field of remote sensing. It’s a phenomenon called “sprite”. In his words: “Thunder is a discharge phenomenon that occurs between clouds and the ground. Sprite is an almost synchronous phenomenon in which the light emission occurs a little later over the thunder at an altitude of 40 to 90 km. An attempt to observe Sprite with an artificial satellite above the clouds from the sky was planned. “

Professor Takahashi began developing an artificial satellite for sprite observation. “The observation with the first satellite ended in failure, but the second that was launched afterwards succeeded in various challenges. A notable achievement is the establishment of a high-precision spectral observation technology through the development of a camera (sensor) that can scan electromagnetic waves (visible light rays, rays in the near infrared) in a wavelength of 1 nm. The camera itself isn’t particularly new, but it was the first for space in the world, and I think its performance is the best in the world in terms of spectral measurement from space, ”says the professor.

On the way to creating an innovative remote sensing project

After his research activities at Tohoku University (where he did his PhD), Professor Takahashi was appointed to the Faculty of Natural Sciences at Hokkaido University in 2009. “A teacher who was part of the same laboratory at Tohoku University moved to Hokkaido University. Since he wanted to build a large telescope to observe planets and invite me to participate, I accepted a post at Hokkaido University, ”says Professor Takahashi about the course of events. Since his appointment, he has been actively involved in projects that use high-precision spectral observation technologies from previous observations. One such project is the “Creating an Innovative Remote Sensing Based on the Spectral Library” project using Hokkaido University’s Spectral Measurement Technology, adopted by the Ministry of Education, Culture, Sports, Science and Education as a Regional Innovation Ecosystem Program (MEXT) .


The moment when DIWATA-1, the Philippines’ first small satellite jointly developed by Hokkaido University and Tohoku University, was launched from the International Space Station (ISS).

In this project, accurate spectral measurement is achieved at extremely low cost by combining a spectral measurement method with a portable measuring instrument and a drone with the world’s most powerful spectral camera from a satellite. By using this, a spectral library is established that covers combinations of sunshine angle and camera direction to greatly improve the accuracy of plant growth and pest diagnosis and to increase the frequency of observation in actual operation.

By significantly improving cost efficiency in this way, it is expected to be a viable project. “It is a strategy to improve the quality of solution services by setting up a spectral library for all angles of incidence and output and by creating a spectral library platform that can get data by simply pointing the camera at any angle,” says Professor Takahashi. He will continue to conduct the world’s most advanced research to create an innovative remote sensing project using high-precision spectral observation technologies.

Yukihiro Takahashi

Professor in the Faculty of Science


Yukihiro Takahashi at home with his beloved cat in Kofu, Yamanashi Prefecture.

Doctor of Science. Specialized in earth and planetary sciences. Dropping out of the regular doctoral course at the Institute of Geophysics of the Graduate School of Science at Tohoku University. Doctorate by submitting a thesis as an assistant, teacher and associate professor at Tohoku University’s Graduate School of Science. Appointed Professor in the Faculty of Science at Hokkaido University in 2009 (current position). Further activities as a leading researcher in earth and planetary sciences are expected in the future.

This article was published in the Spring 2020 edition of Litterae Populi. The full list of articles can be found Here.

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