光子扫描隧道显微镜的角谱传递函数

用傅里叶角谱衍理论推导了光子扫描隧道显笛镜的标量和矢量角谱传递函数。表明，光子扫描隧道显微镜的角谱传递鲜明地分成两个区，即远场区和近场区。随首探针榈间距增大，近场区内的角谱其振幅迅速衰减，频率越高衰减越快，而相位保持不变；相反远场区内的角谱内的角谱其振幅保持不变，而相位非均匀线性均匀线性增加，频率越低增加越快。光子扫描隧道显微镜对近场角谱的采集能力是其皮瑞利衍射极限的关键。坦 步根据角谱传递函数计

Angular Spectrum Transfer Function of Photon Scanning Tunneling Microscope

Analytical expressions for scalar/vector angular spectrum transfer function (scalar-/vector-ASTF) of photon scanning tunneling microscope (PSTM) were derived using Fourier angular spectrum diffraction theorem. The numerical results show that the ASTF of a PSTM consists of two distinct components, the propagating component and evanescent component. For evanescent component, their amplitudes decrease dramatically, and the higher the frequency the faster the amplitudes decreasing, while the phases remain constant as tip-sample distance d increases. For propagating component, their phases increase linearly but not uniformly with d, and the lower the frequency the faster the phases increasing, while the amplitudes remain constant. It is the ability of a PSTM to collect evanescent component that makes it possible to break through the Rayleigh diffraction limit. Based on ASTF the influence of such parameters as tip-sample distance, tip aperture diameter and the incident angle of illuminating laser beam on PSTM image has been discussed.