反射式近场光学显微镜样品近场光分布特性

Near-field optical distribution of sample surface at a reflective near-field scanning optical microscopy

建立了一种反射式近场光学显微镜中样品近场光分布特性的模型,应用矢量衍射理论,得到了系统的场方程。在弱波动条件下,采用微扰法对场方程进行了求解,能方便地得到样品表面的各阶近场光反射和透射模复振幅表达式。计算结果表明,一级场分布要比零级场小一个量级,各阶近场信号的强弱完全由面形函数的傅里叶变换决定。通过与零级结果的比较,证明了计算结果的正确性。提供了一种计算样品表面近场分布简便方法,对反射式近场光学显微镜中调制检测技术具有指导意义。

A theoretical model for the optical distribution of the sample to be observed in a reflective near-field scanning optical microscopy is proposed. Applying the vector diffraction theory, we have established a set of equations to describe the near-field. The complex amplitudes of reflection and transmission modes of all-order near-field distribution are obtained conveniently using perturbation theory in the case of small roughness. The calculation result shows that the near-field distribution of the first-order is one order lower than that of the zero-order. The amplitude of all-order near-field depends on Fourier transforms of surface function. The validity of the calculation result is verified with zero order approximation. This method offers an effective way of calculating the near-field distribution of the sample surface conveniently, and can directly be applied to signal modulation in a reflective near-field optical microscopy.