Accurate 3D-Positioning in a SEM through Robot Calibration

With growing trend of miniaturization, new challenges in microrobotics have appeared. In particular, the complexity of microworld comes from the fact that visual sensors such as Scanning Electron Microscope have a very different principles of image formation in contrast with classical cameras, and their field of view stay very limited. Moreover, usually, the kinematic model of the robots used are not well defined. The consequence of both properties is that even a small movement of the robot arm leads to a huge object displacement comparing to the size of the viewed area. This paper develops a procedure allowing to perform object rotation while keeping it at the same 3D-position in open loop. Such performance is achieved by a method of robot calibration based on visual servoing and autofocus inside SEM. This kind of properties is required for manipulation and 3D reconstruction inside SEM.