Papers by Author: Bo Hua Yin

Abstract: Active disturbance rejection control (ADRC) as an alternative to classical PID control to solving control problems, has gained significant traction these years. With its simple tuning method, robustness against process parameter variations and ability of disturbance rejection, we tried it in our homemade fast atomic force microscope (AFM). Experiments are carried out in contact mode on standard optical grating sample with 50Hz line rate. The results show that ADRC can reject external disturbances well, and can reduce system vibrations obviously.

Abstract: Micro-structure dimension metrology is a grand challenge to current metrological methods and tools. In this paper, a retraceable metrological scanning electron microscopy (M-SEM) system with precision stage and laser interferometer is presented in detail. The double stages structure is used to realize both sample positioning in 50mm×50mm range and accuracy imaging in several tens of micron scale. In order to acquiring metrological scanning image, the control system based on digital signal processing (DSP) is constructed. Furthermore, this paper focuses on demonstrating a metrological SEM image edge detection algorithm which is the essential part of the metrological SEM system to realize the traceable metrology of line width.

Abstract: The system completes the design of signal generator by using the technology of the Direct Digital Synthesizer (DDS). The DSP6713 designed as a key device, realizes outputting triangle wave and sine wave. The digital to analog (D/A) converter circuit is composed of AD768 and LTC1597, which helps improve the speed of converting and modulate the range of the output voltage by Digital Signal Processor (DSP), comparing with using one chip of D/A and proportional amplifier. In addition, bus topology makes extending system functions become easy. The system can be widely used in such field as communication, automatic control and instruments.

Abstract: Scanning tunneling microscope (STM) has several advantages, such as high resolution, and is wildly used. Piezoelectric scanner brings the horizontal resolution of STM up to 0.1 nm, and is it derived by piezoelectric ceramic. Piezoelectric scanner has piezoelectric ceramic’s character. So, piezoelectric scanner output must be calibrated at regular intervals. Graphite atom arrange in a special manner. In the same layer, the distance between adjacent atoms is the same, 0.25nm. This feature can be used to measure length and calibrate small scale scanning. For the 512 × 512 resolution image, the maximum scan range that can distinguish atoms is 30nm2. More large area of atomic image needs to use image stitching technology. By image stitching, small scale scanning, less than 1μm can be calibrated.