Development of a photon scanning tunneling microscope for nondestructive measurements of bio-particles

研究了光子扫描隧道显微镜（PSTM）中必不可少的光纤探针的制备工艺。通过对化学蚀刻工艺的扩展，发展了两步蚀刻工艺。结果，包层直径减小到传统光纤的1/20倍。利用这种细长纤维对探针和样品之间原子力的高灵敏度，开发了一种伺服控制系统，以高精度控制样品-探针的分离。利用该探针组装了PSTM系统，并对其性能进行了评价。以直径为25 nm的沙门氏菌鞭毛丝为参考样品进行评价。采集模式测量得到分辨率约为5 nm的图像。结果表明，增大探针孔径、增大样品与探针的分离度会降低图像的分辨率。这种依赖关系更符合我们之前提出的基于“虚光子”模型的理论结果。此外，还发现分辨力与入射光的偏振态有关。根据光致极化在表面上的空间分布，解释了这种依赖关系。为了评估光照模式PSTM的性能，神经元作为参考样本。在不将其从轴突中取出的情况下，成功地成像了分支轴突中的微管束（电子显微镜观察到的名义直径为25 nm）。测量直径为25nm，与公称直径完全一致。实验结果表明，该PSTM具有与电子显微镜诊断生物样品相同的分辨率。虽然上述实验结果是在空气中获得的，但我们也成功地对水中沙门氏菌鞭毛丝的多钩进行了成像。少

Fabrication process of an optical fiber probe was developed, which is an essential device for the photon scanning tunneling microscope (PSTM). By extending chemical etching process we have developed previously, the two-step etching was developed. As a result, the cladding diameter was reduced to 1/20 times that of the conventional fiber. By utilizing a high sensitivity of this slender fiber to the atomic force between the probe and sample, a servo-control system was developed to control the sample-probe separation with high accuracy.The PSTM system was assembled by using this probe and its performance was evaluated. Flagellar filaments of salmonella were used as a reference sample for the evaluation, which has the 25 nm diameter. Collection-mode measurement obtained the image with the resolution of about 5 nm. It was found that the resolution of the image was reduced by increasing the aperture diameter of the probe, and by increasing the sample-probe separation. This dependency agreed … More with the theoretical results based on the "virtual photon" model, which we have proposed previously. Futhermore, it was found that the resolution also depended on the polarization-state of the incident light. This dependency was explained based on the spatial distribution of the light-induced polarization on the surface.To evalute the performance of the illumination-mode PSTM,neurons were used as a reference sample. The bundle of microtubulines (nominal diameter observed by an electron microscope was 25 nm) in the branching axon was successfully imaged without taking them out from the axon. The measured diameter was 25 nm, which is exactly the same as the nominal diameter. From this result, it was confirmed that the present PSTM has the resolution as high as that of the electron microscope for diagnosing biological samples.Although the experimental results described above was obtained in the air, we have also succeeded in imaging the polyhooks of the flagellar filaments of salmonella in the water. Less