Fig. 1. Formation mechanism of out-of-focused-plane displacements

Fig. 2. In-focused-plane and out-of-focused-plane displacements generation using spatial nano-positioning stage （NPS）

Fig. 3. Generated displacements in focused-plane and synchronously out of focused plane using end-effector of proposed NPS

Fig. 4. Experiment setup of micro-vision motion-tracking system

Fig. 5. One-step motion characteristic of lifting platform

Fig. 6. Searching for the focused plane

Fig. 7. Image sharpness function for searching focused-plane

Fig. 8. Searching procedure for focused-plane

Fig. 9. Repetition accuracy for searching focused-plane

Fig. 10. Accuracy degradation of micro-vision motion-tracking causing by out-of-focused-plane displacements

Fig. 11. Threshold values of out-of-focused-plane displacements to disable micro-vision motion-tracking system