Papers by Keyword: Laser Interferometer

Abstract: Dimensional inspections in manufactured workpieces allow assess the quality of the manufacturing process, in this context the quality and development of measurement systems are issues addressed by many researchers. The coordinate measuring machines (CMMs) are versatile systems, can measure complex geometries quickly and accurately. Positional errors are parts of volumetric error and affect the correct positioning of probe in CMMs or of the tool in machine tools. Faced with this, the purpose this investigation is show a method to calibrate the positional errors in a bridge-type coordinate measuring machine, this method collects data in dynamic mode and reduces cyclic errors. The calibration of positional errors was performed using laser interferometry in the “on-the-fly” mode and a method to reduce cyclic errors was applied. The highest value of position error occurred in x axis with value positive of 10μm in the position of 220mm, while in the y and z axis the higher absolute values were 2μm and 6μm respectively. From calibration and compensating of positional errors it is possible to reduce the effects of the volumetric errors in machines with axis of linear displacements as the CMMs and machine tools.

Abstract: Understanding and measuring the displacement characteristics of piezoelectric ceramic with electric field exciting are particularly important. The piezoelectric coefficient d₃₃ as the indication of its displacement characteristics, is the key parameter of its energy transformation. In this paper, the characteristics of two kinds of piezoelectric ceramics, PZT4 and PZT5 were studied by the laser interferometer measurement. The influence factors of d₃₃ were studied, including the frequency and amplitude of the exciting signal, the ways of holding, and the loading sequence. Then the measurement results of piezoelectric ceramic with laser interferometer and the quasi-static method were compared, the results showed they had consistence and the analysis of the piezoelectric coefficient d₃₃ measurement by converse piezoelectric effect and by piezoelectric effect was discussed.

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 screw pitch error of the ball screw is the primary error source of reducing positioning accuracy during the process of error compensation. When using the laser interferometer compensated the screw pitch error, it was difficult to eliminate the influence of the screw pitch error on the positioning accuracy just by the first compensation .this study proposed the secondary compensation method of the screw pitch error based on the initial compensation. in order to avoid the negative effect of the high prices of the automatic compensation software, the fallibility of the manual compensation and the low efficiency of the manual compensation, this article developed a pitch error rapid compensation software. the experiment result demonstrates that the precision index of the CNC machine tools and the efficiency of compensation can be improved obviously by comprehensive using the secondary compensation method and the pitch error rapid compensation software.

Abstract: In this paper, we propose a signal compensation algorithm. In heterodyne laser interferometer, the unexpected error restricts the precision such as nonlinearity and environmental error. To improve the accuracy in length measurement, we use the method of Lagrange multiplier which solves the constrained optimization problem and allows to minimize an objective function. With the method of Lagrange, we apply it to a length measurement and show the result of simulation.

Abstract: In this paper, we propose a seismic wave detection process using a laser interferometer as a seismometer. The laser interferometer system is an important equipment with its remarkable accurate capability for displacement measurement. During the process of the seismic wave measurement, however, environmental and nonlinearity error are occurred in a heterodyne laser interferometer. Through the extended Kalman filter compensation, the distortion is reduced. With a recursive STA/LTA algorithm, the PS-time of the seismic wave is determined and then the epicenter distance can be derived. Through some simulations, it is demonstrated that the proposed algorithm can reduce error factors and improve the measurement accuracy of a seismometer.

Abstract: Through the methods using combination ball-bar with laser interferometer, we carry on accuracy measurement and error compensation of three-axis CNC milling machine. We finally find out the main factors affecting the machining accuracy of machine tool. In the meantime we can improve repeatability of positioning accuracy and the machine's positioning and meet the processing needs by means of the existing error compensation of the CNC machine tools.

Abstract: This paper introduced a kind of fast tool servo (FTS). Base on in the frame rack, flexible hinge, piezoelectric ceramic driver, tool base, diamond tools and so on. Laser interferometer is used for displacement measuring of the fast tool servo. The structure simulation was done to the FTS and the nature frequency was obtained. The output displacement of FTS was measured by Laser interferometer. Four kinds of different sin wave sign were given and the frequency of driving voltage ranged from 10Hz to 400 Hz. The relation of the displacement and the driving voltage frequency and the relation of displacement and the driving voltage had been established by experiment.

Abstract: The positioning accuracy of CNC machine tool is the best moving position accuracy which the machine tool can reach under the control of CNC control system. The principles of frequency laser interferometer measurement are described in this paper, and pitch error is compensated by taking DAHE V1500 CNC machine with FANUC system as example. The result shows that the precision of CNC machine tool is effectively improved.

Abstract: Antenna is an important and valuable component in industry. In order to protect it, the radome is adopted. As the non-uniform thickness of radome affects the performance of the antenna, in order to maintain the performance of antenna, it is necessary to have a dedicated device to detect the radome, thus the detection machine tool is used. The accuracy is the key point of the detection machine tool, so in this paper, its error model and measurement are presented. By the pitch compensation, the accuracy is enhanced, which achieves the desired value.