Papers by Author: Jun Guo

Abstract: White-light interferometric technique has been widely applied in the measurement of three-dimensional profiles and roughness with high-precision. Based on the characteristic of interferometric technique, a new method combined with image location and a three-dimensional stage is proposed to achieve the non-contact absolute shape measurement for aspheric and spherical surface in a slarge range. The interference fringes vary with the horizontal displacement of the measured surface, the surface information was obtained by locating the transformation of the maximal intensity in the interferograms. Two main influence factors are discussed; they are performance of the inerferimetric microscope and the stage. Since the performance of the stage directly determines the measurement precision, a three-dimensional displacement stage with a large range and a high precision was developed. Some experiments were carried out to verify the performance of the three-dimensional displacement stage and the validity of the new measurement method with satisfactory results.

Abstract: This paper describes an X-Y stage with a plane cross grating for position feedback. The stage has a current servo motor and a piezoelectric actuator to realize coarse and fine positioning throughout the 50mm x 50mm range of travel. The objective table contacts tightly on a planar wafer to enhance the motion flatness. The horizontal positioning noise is less than 20nm. The stage has a positioning accuracy of 3µm. If a high quality grating and guide is used, it should be useful for 3D surface measurement and ultra-precision machining. The operating principle and the characteristics of the plane cross grating are presented. The internal structure is explained. The comparison result for the stage with a laser interference calibration is presented. The theoretical precision and error sources of the system including grating grid, guide and grating installation error are analyzed. Experiments on factors such as system noise, guide error and motion interference are presented and the results are analyzed.

Abstract: As a special surface texture evaluation method, motif has received much attention since it was adopted as an ISO standard which is ISO12085 1996. However, like many other evaluation methods, it is based on 2 dimensional lines. The surface itself is three dimensional in nature. 3D motif evaluation should be more suitable. Until now, no 3D motif evaluation method has yet been proposed. A key issue is 3D motif combination to determine how the evaluation should be implemented. Three types of 3D MOTIF combination methods currently used are examined. Features such as algorithm complexity and application range are investigated. We conclude that the best 3D Motif combination method is not currently available. We should select a combination method based on the need for surface function analysis. Hybrid methods are also recommended.