Integrated visual nanometric three-dimensional positioning and inspection in the automated assembly of AFM probe arrays

This paper presents the design of a monocular three-dimensional artificial vision system attached to a 20× microscope lens for precision and microsystems applications. Possible uses in assembly include: positioner calibration, sensor-based part handling, positioning, and inspection in the nanometric range. The developed image acquisition method - along one direction (in steps of 100 nm), the depth-from-focus algorithm and subpixel interpolation (of 5 acquisitions for concurrent localization and inspection), allow to overcome the physical optics limitation achieving a resolution under 200 nm. The vision strategy and algorithms, described in the paper, have been validated by handling an AFM probe array by a micropositioner.