エバネッセント光を利用した分子間力3次元測定可能な光学顕微鏡の試作

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The major goal of our project was to establish a methodology which enables us to simultaneously image and manipulate single molecules under an optical microscope. We attempted to combine two techniques, namely, an optical trapping and evanescent excitation microscopy. To do this, we drastically modified an old methodology to create the evanescent field at glass-water interface : we utilized a coverslip as a waveguide so that a YAG or an argon ion laser beam excuse total internal reflection multiple times and reach the desired position of the coverslip where sample is located. This methodology was anticipated to be coupled to the optical trapping technique in less interfering manner than the conventional method to create the evanescent field. The optical trapping and the new evanescent excitation method satisfactorily well : we could measure the actomyosin motor force, cohesive force between actin and alpha-actinin, or we could observe single fluorescent molecules at the glass-water interface. When the two methods combined, a problem which was not anticipated before appeared : aberration of the objective lens against the infra-red laser beam used for the optical trap was far stronger than our anticipation and it was almost impossible to use optical trap under the setup we utilized. We hence searched other ways, but found the problem should be resolved by designing a new objective lens with aberration is corrected for infra-red wavelength region. At present, the usage of the infra-red wavelength light as a excitation light source for fluorescence microscopy, close cooperation with microscope manufacturer will be the most urgent to approach and achieve our goal.