A simple method based on vision for obtaining depth information in nanomanipulation

Nanomanipulation system based on scanning electron microscopes (SEM) provides researchers with an increasing ability to interact with objects at the nanoscale. But it is difficult to accomplish a nanomanipulation task due to the lack of the depth information. This paper presents a visionbased method for detecting the contact between an end-effector and a target surface inside an SEM without adding any extra facility or sensor. The theory analysis of contact detection is given. The experimental results show that the proposed vision-based method is capable of obtaining contact points two times (approach and retract) in one contact detection process and achieving a one-pixel detection accuracy about 20 nm at 10000x magnification.