A magneto-optical (MO) microscope that uses the polarization modulation method has been developed for quantitative MO imaging. In this technique, images of MO rotation and ellipticity are reconstructed from three images for different polarization states; i.e., linear, right-circular, and left-circular polarization states. The three polarization states are generated either by rotating a quarter-wave plate or by changing the voltage applied to a liquid crystal modulator (LCM). Measurements are performed using a patterned thin film of Bi,Ga-substituted yttrium iron garnet prepared on a glass substrate. The values of MO rotation and ellipticity obtained from the images for several wavelengths between 450 and 650 nm are found to agree quantitatively with those obtained by an MO spectrometer. Hysteresis loops at any point of the image can be displayed by simply placing a pointer at the position. A real-time MO imaging with a rate of 1 frame/s is also achieved by using the LCM and a high-speed charge-coupled device camera.

Impact of climate change on marine biogeochemical parameters and ecosystem is one of the important issues of our environment. Direct evidence of marine pelagic ecosystem changes is found with warming of sea water and sea-level rise in the main stream of the Kuroshio in the East China Sea and the western North Pacific during these three decades based on the analysis of long-term comprehensive hydrographic observations. In terms of annual mean, the warming rate of surface air temperature and sea surface temperature ranged from 0.15 to 0.21°C per decade in and around the main stream of the Kuroshio in the East China Sea, which exceed the global mean warming rate of 0.128 ± 0.026°C per decade during the period from 1956 to 2005 reported in IPCC 2007. One of the features in this rapid warming region is an increase of number of Pterosagitta draco, a cosmopolitan warmwater zooplankton. Biogeochemical parameters, such as wet weight of zooplankton, plant pigment and nutrients concentration in the upper 200 m have been decreasing while dissolved oxygen content and seawater temperature have been increasing in the upper 200 m in the main stream of the Kuroshio in the East China Sea. These observed linear trends of the biogeochemical parameters would be foresights for temperate oceans in the future.

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We propose and demonstrate a novel measurement technique for determination of n and t, where the measurement time is only 1 s or less for a thickness of <1 mm. Such a high-speed measurement is successfully achieved by simultaneous detection of coherence-gate and confocal signals with a single scanning of the sample. A measurement accuracy of 0.3% or less was successfully attained for a thickness of <1 mm. A multi-point measurement result is also presented for the index and thickness distributions of a radial-graded-index rod lens.

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