The image quality and accuracy of the atomic force microscope are seriously affected due to drift and hysteresis of Piezoelectric positioning platform. Currently, the distortion correction methods had been confined in tracking a certain area or image correction after images are acquired, which makes it difficult for the atomic force microscope (AFM) to obtain low distortion images. In this study, the scanning path of the AFM is redesigned. The scanning route is spiral in a whole with many blocks which are scanned once at a time, and the drift of blocks is corrected in real-time during the scanning process. This method is suitable for real-time correction of drift during long-time scanning, compared with the traditional scanning method.
A high-precision two-dimensional (2D) coplanar micro-vibration generator with a flexure decoupling mechanism is proposed in this study. The generator is composed of a 2D symmetrical coplanar platform and a slider pair. The 2D coplanar platform structure is fully symmetric to achieve decoupling of motion in the X and Y directions. The vertical support with a slider pair is used to guarantee strict planar motion with heavy loads. Under open-loop control, the developed generator has the capability of translational motion stroke of 48.71 μm and 49.10 μm in the X and Y directions, respectively, and the maximum coupling error is approximately 0.78%. A PID control system was designed to realize the closed-loop control of the vibration generator. The control system can effectively reduce the inertial vibration and settling time of the generator. In addition, the closed-loop controlled vibration generator also has good motion tracking characteristics.
Low-frequency vibration is a harmful factor that affects the accuracy of precision machining and high precision measurement. Low-frequency micro-vibration cannot be completely eliminated by air-floating platforms. Therefore, lowfrequency vibration must be measured with high-precision before being suppressed actively. A low-cost high-sensitivity low-frequency optical accelerometer is proposed. This optical accelerometer mainly consists of three components: a seismic mass, a leaf spring, and a displacement sensor (four-quadrant photodetector). When vibration is detected, the seismic mass moves up and down due to the effect of inertia, which is amplified by using an optical lever and measured by the four-quadrant photodetector. Then, the acceleration can be calculated. The resonant frequencies and elastic coefficients of various seismic structures are simulated by ANSYS software to attain the optimal detection of lowfrequency low-amplitude vibration. The accelerometer is calibrated using a homemade vibration calibration system, and the calibration experimental results demonstrate that the sensitivity of the optical accelerometer is 4.92 V (m·s−2 ) −1 , the measurement range of the accelerometer is 0.0095–2.58 m·s−2 , and the operating frequencies range from 5 Hz to 15 Hz. The efficacy of the optical accelerometer in measuring low-frequency and low-amplitude dynamic responses is verified.
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