Weiguo Bian

Bio: Weiguo Bian is an academic researcher from Soochow University (Suzhou). The author has contributed to research in topics: Calibration (statistics) & Scanning electron microscope. The author has co-authored 2 publications.

Scanning Electron Microscope Calibration with SE2 and Inlens Detectors

Abstract: In this paper, we proposed an ideal that calibration in the scanning electron microscope (SEM) with SE2 detector and Inlens detector. The parameters (intrinsic and extrinsic) were both achieved. This approach required rotation and translation of the chessboard calibration to obtain multi-images. Experiments were realized by varying the orientation and the position of chessboard pattern from different work distance (WD). It can be seen from the calibration results that the SE2 detector and the Inlens detector have different overall average pixels at different work distances. By comparing the calibration results, it was found that the two detectors had close pixel errors when the work distance was between 6.4mm and 6.5mm. The results show that the calibration approach was accurate and efficient.

Adaptive Threshold Processing of Secondary Electron Images in Scanning Electron Microscope

Abstract: Observing the sample under a scanning electron microscope (SEM) requires adjustment of brightness and contrast to obtain a clear image. The traditional method is manually adjusted by the operator, which inevitably has errors. In this paper, an adaptive threshold processing method based on image-based normalized gray histogram is proposed. This method can acquire the threshold of the image according to the state of the currently obtained secondary electron images. When the brightness and contrast of the image change, the threshold can also be changed accordingly. It is concluded from a large number of tests that when the secondary electron image gray histogram has obvious double peaks and is located in the trough, the threshold obtained is optimal. Therefore, it is possible to better observe the pictures under the SEM.

Zooming-Free Hand-Eye Self-Calibration for Nanorobotic Manipulation Inside SEM

Abstract: Nanorobotic manipulation inside Scanning Electron Microscope (SEM) is widely used in nanomaterial characterization and assembly tasks. However, tedious and time-consuming hardware regulations, like axis alignment, are still critical and mandatory to keep the functionality of nanorobot systems. This article proposes a novel zooming-free hand-eye self-calibration method for nanorobotic manipulation inside SEM to circumvent the hardware regulation problem, which is applicable to a wide range of system configurations. The hand-eye relationship calibration method is based on the active incremental motion of the nanorobot without referring to expensive and complicated calibration patterns. Both perspective projection at low magnification and affine projection at high magnification are modelled, and unified by the image Jacobian matrix technique. With several times active calibration at different magnification factors in advance, the hand-eye relationship can be, thereafter, determined from the model at arbitrary status. The calibration model can be applied to both accurate SEM visual measurement and precision visual servo control. The corresponding methods regarding two-dimensional (2D) measurement, in-plane positioning, and constrained three-dimension (3D) positioning based on the proposed hand-eye relationship model are also presented in this article. Experiments show that practical contact between robot end-effector and silicon nanowire under 1500× is well established with standard deviation less than one pixel.