Near-field optical microscopy using an organic thin films as a detection system and its application for the observation of biological specimens

近场扫描光学显微镜(NSOM)已被许多研究人员广泛研究，因为使用近场扫描光学显微镜可以克服光学显微镜分辨率由光的衍射极限决定的局限性。NSOM可以观察到样品的折射率。与原子力显微镜(AFM)或扫描隧道显微镜等其他扫描探针显微镜相比，这是NSOM的独特优势，这些扫描探针显微镜在测量样品形貌方面具有非常强大的工具。由于NSOM需要探针尖端的扫描时间来获取样品的图像，因此很难应用于观察活的样品或移动的生物样品或非常快的现象。我们开发了一种新型的近场显微镜，它使用有机薄膜作为光的探测系统。在近场显微镜中，样品附近的光场分布被记录为光敏薄膜的表面形貌，并用原子力显微镜读出形貌分布。由于近场显微镜不需要扫描探头尖端来照明、检测或散射光，因此可以观察移动的生物样本和快速现象。我们用亚波长分辨率演示了草履虫和纤细草履虫的移动观察。

The near-field scanning optical microscope (NSOM) has been extensively investigated by many researchers, because it is possible with such a microscope to overcome the limitations of optical microscope resolution that are determined by the diffraction limit of light. The NSOMs can observe the refractive index in specimens. This is a unique advantage of NSOMs in comparison with other scanning probe microscopes such as the atomic force microscope (AFM) or the scanning tunneling microscope, which are very powerful tools in the measurement of specimen topography.Since the NSOMs require the scanning time of a probe tip to acquire an image of a specimen, they are difficult to apply to the observation of living specimens or moving biological specimens or very fast phenomena.We have developed a new type near-field microscope using an organic thin film as a detection system of light. In the near-field microscope, the optical field distributions near the specimens are recorded as the surface topography of a photosensitive film, and the topographical distributions are readout with an atomic-force microscope. Since the near-field microscope does not require the scanning of a probe tip for illumination or detection or scattering of light, it is possible to observe moving biological specimens and fast phenomena. We demonstrated the observation of a moving paramecium and euglena gracilis with subwavelength resolution.