激光光强分布对原子力显微镜中光学偏转法检测结果的影响

Influence of Distribution of Light Intensity of Laser Source on Detecting Results of Optic deflection Detecting in Atomic Force Microscope

从光学偏转超微力检测原理出发，严格地分析了在激光光源具有一定空间光强分布的情况下其检测的结果。我们发现激光源的空间光强分布在超微力检测条件下对检测结果没有影响，即其ＰＳＤ的输出信号完全正确地反应了悬臂梁的受力大小。但是，ＰＳＤ所检测光斑的重心位置对应的光线将随悬臂梁受力大小的不同而不同。本文给出了入射光经弯曲悬臂梁反射后空间光强分布变化的计算方法和计算实例。

In this paper,the detection results in the case that laser light source has a certain space distribution of light intensity are critically analysed on the basis of detecting principle of optic deflection ultra microforce detecting.We find that the space distribution of light intensity of the laser source has no influence on the detecting results on the condition of ultra microforce detecting.That is the output of PSD completely and correctly reflects the value of the force acting on cantilever.Howeve,with different values of force acting on cantilever the lights corresponding to the position of weight center of light spot detected by PSD are different.Calculation method and calculation example of the variation of the space distribution of light intensity of incident light after reflected by the deflected cantilever are also given,and suggestion for further extraction the information of the above mentioned variation from the reflected beam and putting it in use is pointed out in the article.