In order to get to the peak of Mauna Kea (4,207 m—the highest point in Hawaii), one needs to take a break at the Hale Pohaku rest area and become acclimatized to the altitude and thinning air. Waiting for the night, one begins to walk towards the goal, turning off a helmet light and relying on a flashlight.
Soon Subaru appears: a cylindrical astronomical telescope, the pride of Japan. The telescope consists of a perfectly polished curved surface mirror, 8.2 m in diameter, yielding excellent research results. I learned that the telescope carries a volume phase holographic (VPH) grism, developed by the team at the Kodate Laboratory at Japan Women’s University.
While young people in Japan are losing interest in pursuing a career in science and technology, JWU (the only private women’s university in Japan that has a faculty of science) has been successfully producing female scientists who love what they do—which is evinced by the grism I saw. I think it is a wonderful achievement.
–Atsuko Toyama, former Minister of Education in Japan, from the foreword in For a Brighter Future for Women in Optics, K. Kodate, Ed., Optronics Co. Ltd., Tokyo (2007) (translated from Japanese).
The former minister of education’s warm support for and recognition of my team’s work on the VPH grism is one example of the far-reaching effects of the research and development effort at the JWU Kodate Laboratory and the work we do to increase the number of women in the sciences.
The VPH grism is a high-dispersion and high-performance device for the Subaru telescope which consists of a thick VPH grating sandwiched between two prisms, as shown in the diagram at right. We constructed it in 2003 using a high-viscosity, liquid photopolymer and a rigorous coupled-wave analysis program which takes into account the refractive index modulation of the grating. (The grism measures 110x106 mm2 with a groove of 1000~1600 lines/mm. Diffraction efficiency is in the range of 84–90%, and resolution is 3000 to about 7900.)
Since that time, grisms for the near-infrared region have been developed by employing optimum exposure conditions and an active-phase-control technique. These grisms were to be installed into the Multi-Object Infrared Camera and Spectrograph (MOIRCS) of the Subaru telescope in June 2010.
Better views of the stars
The field of view on the MOIRCS is 4 x 7 square arcminutes with a spatial resolution of 0.117 arcsec/pixel projected on the sky. MOIRCS can acquire 40-50 object spectra simultaneously with cooled-slit masks across a wavelength range of 0.9~2.5 microns. With these developments, astronomers can observe our solar system, nearby galaxies, star-forming regions, and high-redshift galaxies in both spectroscopic and imaging modes.
Diagram of the Volume Phase Holographic (VPH) grism.
This is but one piece of the massive effort to understand galaxy formation in the early universe.
As with the work on the VPH grism, other research at the Kodate Laboratory is aimed at finding practical applications and devices that can solve problems in our society and answer important scientific questions. Our research ranges from micro-optics to diffractive optical elements, from numerical analysis to photonic signal processing.
The current focus of our lab is in the area of optical correlation technology, and we are the leading research group in this subject. We have applied this technology to facial recognition and videos, and we are making good progress toward bringing optical computing technology to market.
Spinoff company from JWU
To better serve our society and give something back using the research from our lab, we established a venture company in 2008, Photonic System Solutions Inc. (PSS), as a spinoff from JWU.
PSS conducts research in the optics field, such as with VPH grisms and optical correlation. We also license our technology and commercialize the applications.
Tracking movie stars, too
Our research into optical correlation has led to the development of a powerful online video-matching application called Fast Recognition Correlation System, or FReCs, that monitors the use of copyrighted videos on the Internet. Using optical correlation algorithms, the FReCs software system can correlate content on multiple videos at very high speeds.
The new optical correlator uses a holographic disk.
By filtering online videos, FReCs allows video makers to patrol video-sharing websites and detect video content that copyright holders register with the FReCs database. When matched video content is detected and copyright permission has not been obtained, FReCs can send out a request to have the content removed. It then monitors the video file on the website until it is taken down.
Other functionalities built into FReCs allow users to easily manage copyrighted materials on the Internet, and PSS has developed it to be a full-featured online video copyright management system.
In early 2009, PSS started deployment of FReCs for major publishers and television networks in Japan as well as other copyright holders. The system has successfully filtered out a number of unauthorized video content on the Internet.
Today PSS is the major service provider for online video copyright management in Japan, and not merely for the private sector. We have also worked with the Japanese government and are tasked with investigating the current trend of pirated video content on the Internet.
Fast optical correlation
It is clear from our investigation that the volume of unauthorized content on the Internet is growing at a fast pace, and there will be a need for a more effective video-filtering system in the near future. In order to meet this demand for ever-quicker detection, PSS is developing an optical correlation server, FARCO.
FARCO enhances the software correlation process of FReCs with optical correlator hardware using a holographic memory disk. In lab testing, FARCO has successfully achieved the correlation process more than 100 times faster than the current software-based FReCs system. When the final optical computing hardware is completed, FARCO will replace FReCs as a practical, optical-computing application.
The use of optical computing has been a dream for many researchers in the field of optics for decades. We, as a team of PSS, are small in number (11 employees), but consist of both men and women striving to make this dream a reality.
This is also an exciting model of what female scientists can offer to society.
To learn more about our research and technology, please see www.psss.co.jp or contact us at email@example.com. For more on the fast facial-recognition optical correlator, see the 2006 SPIE Newsroom article.
Women in Science
Despite conscientious efforts by Japan Women’s University, the Japanese government, and others to increase the number of women in science, the percentage of female scientists in Japan is small, compared to most countries. A recent report from Japan’s National Institute of Science and Technology Policy estimates that only 13.4% of the researchers in Japan are women.
That percentage lags far behind many other countries surveyed, including Portugal, where women account for 44% of the scientists. More than 30% of the scientists in 11 other European countries are women.
(The NISTEP report didn’t cover the United States, China, and some sectors of the UK. The National Science Foundation estimates that women represent 27% of the science and engineering workforce in the United States.)
The SPIE Women in Optics group promotes personal and professional growth through community and network building and by encouraging young women to choose optics as a career.
Subaru is an 8.2-meter optical IR telescope in Hawaii operated by the National Astronomical Observatory of Japan (NAOJ), National Institutes of Natural Sciences. Its first light was in January 1999 and open use began in December 2000.
Photo © NAOJ.
The Multi-Object Infrared Camera and Spectrograph (MOIRCS) at the Subaru Telescope is a Cassegrain near-infrared instrument with a wide field of view. MOIRCS can acquire about 40 object spectra simultaneously across 0.9~2.5 micron wavelengths.
Kashiko Kodate is president of PSS Inc. in Tokyo and professor emeritus at Japan Women’s University in the Department of Mathematical and Physical Science. Her research concentrates on diffractive optics and its application to optical information systems, such as facial recognition, arrayed waveguide gratings, Talbot array illuminators, and optical interconnection. She is a graduate of JWU and received her PhD in electronic engineering from the University of Tokyo. She is the adviser to the SPIE Student Chapter at JWU.
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