AFM悬臂定位系统中光干涉误差及减小方法研究

光杠杆法是原子力显微镜（AFM）悬臂定位的主要方法。由于悬臂自身的尺寸和材料特性、检测光路系统等因素制约，悬臂弯曲测量时存在光泄露。被试样表面反射的部分泄露光与悬臂反射光产生干涉，在探针一试样接近曲线中产生光干涉误差。基于轻触模式AFM，分析了光干涉误差的产生原因，并对其引起的AFM测量误差进行了数学分析和仿真、提出了减小光干涉误差的方法。实验结果和理论分析表明，为了进一步提高AFM的测量精度，有必要克服定位系统中的光干涉误差。

Research on optical interference error in cantilever''''s positioning system of AFM and its reduction methods

Optical lever method is a main technique to detect the cantilever's position in atomic force microscope (AFM). Due to the limitations of cantilever's dimensions, characteristics of cantilever material and detecting optical system, the leakage of detecting light exists in the cantilever's positioning system. Some leaked light scattered by sample surface interferences with the light reflected by the cantilever. Therefore, an optical interference error occurs in the probe-sample approaching curve. Based on the tapping mode AFM, the factors causing the optical interference error are analyzed; the AFM measurement errors caused by the optical interference are deduced mathematically and simulated; several methods are put forwards to reduce the error. Experimental results and theoretical analysis show that in order to improve the measurement accuracy of AFM, it is necessary to overcome the optical interference error in the cantilever's positioning system.