“禁戒光”近场光学显微镜原理与系统

扫描近场光学显微术是８０年代后期发展起来的一种分辨率超过衍射极限的新型光学显微镜技术。本文介绍了国外最近出现的“禁戒光”近场光学显微镜系统的工作原理及结构。透射式ＳＮＯＭ中部分光沿着光轴向前传播；部分光沿着大于全内反射临界角的方向传播。前者称为允许光；后者称为禁戒光。应用“禁戒光”近场光学显微镜可同时获得三幅图像，即允许光像、禁戒光像和反映样品表面形貌的剪切力图像。禁戒光图像能够提供很好的对比度和分辨率。

Theory and System of “Forbidden Light” Near Field Optical Microscope

Scanning near field optical microscopy is a new technique developed in the late 1980s. The microscope of this kind can detect samples with nanometric resolution when the probe/sample distance is within nanometric scale. A new theory and instrument, called “Forbidden Light” or “Tunnel” near field optical microscope (FL SNOM or TNOM) recently developed in the US are described in this paper. Light emitted from the aperture of a near field optical probe in the close vicinity of a dielectric object propagates in classically “forbidden” as well as “allowed” directions; the two zones are separated by the critical angle for total internal reflection. The new “forbidden”nearfield optical microscope can obtain three images simultaneously, namely shear force image, forbidden light image and allowed light image. Forbidden light can provide high contrast and resolution even in the situations in which standard SNOM shows little or no contrast.