Papers by Author: Xiang Qian Jiang

Abstract: This paper presents a methodology for validating surface metrology software. Based uncertainty analysis, a set of reference data sets with mathematical correct results, call the type F1 softgauges, have been developed. Special designed profiles can be used to check specification uncertainty and algebra calculation is used to lower method uncertainty. The results shown that specification uncertainties were main uncertainty contributors.

Abstract: The detection of stationary and non-stationary noise in environmental vibration data is an important issue when considering the precision of the Watt balance, an electromechanical apparatus for the new definition of the kilogram in the international system of Units (SI). In this paper, the authors propose a frequency histogram method to find the structure of the stationary noise from large amount of datasets. For the non-stationary noise, the authors propose a wavelet based denoising methods to distinguish the transient events from the background “noise”, to find their duration and content and to identify their location in time.

Abstract: This paper presents a study of effect of cutting conditions on surface quality in FTS machining of optical microstructures such as micro-lens array. A power spectrum analysis is proposed to characterize the surface quality in FTS machining. It is found that there is a strong relationship between the surface roughness and the power spectrum of the surface profile. This provides an important means for the characterization of surface quality in FTS machining of optical microstructures.

Abstract: To meet the requirements of next generation Geometrical Product Specification and Verification (GPS), a surface texture information system integrated with AutoCAD is developed. The information system mainly consists of three parts: a surface texture database containing large amount of surface texture specification information, inference algorithms and interfaces with AutoCAD, so that unambiguous, explicit and complete specification for design, manufacture and verification of surface texture can be provided in AutoCAD for function assurance.

Abstract: A new signal-denoising approach based on DT-CWT (Dual-Tree Complex Wavelet Transform) is presented in this paper to extract feature information from microstructure profile. It takes advantage of shift invariance of DT-CWT, non-Gaussian probability distribution for the wavelet coefficients and the statistical dependencies between a coefficient and its parent. This approach substantially improved the performance of classical wavelet denoising algorithms, both in terms of SNR and in terms of visual artifacts. A simulated MEMS microstructure signal is analyzed.

Abstract: The rate of increasing storage capacity is being slowed by the inability to produce ever closer flying heights between the sliders and disks. In order to allow the sliders to ‘fly’ faster and more closely to the disk surfaces, it is important to control the surface of substrates of hard disks to a super-smooth level. However, there are no sophisticated instruments and assessment standards for super-smooth surfaces. In this research, the authors attempt to build a measurement and assessment protocol for the evaluation of super-smooth surfaces using a white-light optical instrument CCI (Coherence Correlation Interferometer). The key advantage of this instrument is its exceptionally high vertical resolution which is an order of magnitude better than comparable systems. This paper focuses on discussing the factors influencing the experimental results; they include sampling intervals, the number of measurements, scan size, filter cut-off wavelength etc. Based on the experimental results, an optimum protocol for measurement and assessment are recommended, and then the authors measure and compare the surface roughness of six hard disks derived from differing chemical mechanical polishing (CMP) ‘abrasives’. It has been found that: (1) the roughness values of the six hard disks surfaces have all reached a sub-nanometre level; (2) CMP regimes have little influence on the topography of the hard disk surfaces.