Journal Article Reflecting microscope system with a 0.99 numerical aperture designed fro three-dimensional fluorescence imaging of individual molecules at cryogenic temperatures

稲川, 博敬  ,  Inagawa, Hironori  ,  虎谷, 泰靖  ,  Toratani, Yasuharu  ,  本橋, 和也  ,  Motohashi, Kazuya  ,  中村, 一平  ,  Nakamura, Ippei  ,  松下, 道雄  ,  Matsushita, Michio  ,  藤芳, 暁  ,  FUJIYOSHI, SATORU

5p.12833 , 2015-08 , Nature Publishing Group
We have developed a cryogenic fluorescence microscope system, the core of which is a reflecting objective that consists of spherical and aspherical mirrors. The use of an aspherical mirror allows the reflecting objective to have a numerical aperture (NA) of up to 0.99, which is close to the maximum possible NA of 1.03 in superfluid helium. The performance of the system at a temperature of 1.7 K was tested by recording a three-dimensional fluorescence image of individual quantum dots using excitation wavelengths (λ ex) of 532 nm and 635 nm. At 1.7 K, the microscope worked with achromatic and nearly diffraction-limited performance. The 1/e2 radius (Γ) of the point spread function of the reflecting objective in the lateral (xy) direction was 0.212 ± 0.008 μm at λ ex = 532 nm and was less than 1.2 times the simulated value for a perfectly polished objective. The radius Γ in the axial (z) direction was 0.91 ± 0.04 μm at λ ex = 532 nm and was less than 1.4 times the simulated value of Γ. The chromatic aberrations between the two wavelengths were one order of magnitude smaller than Γ in each direction.

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