Yuhe Li

Design and Analysis of a Novel Micro Flying Head in Mass Storage System

In order to meet the mass storage system’s need for higher density and integration, a novel structural design for micro flying head is conceived and an air bearing surface is designed based on micro fluid theory of hydrodynamics. Both positive and negative pressures can be generated by the air bearing surface, with the stiffness and motion stability enhanced by negative pressure. A lubrication model has been investigated with 1.5 order slip model of the generalized Reynolds equation, and the finite volume method is used for the simulation of the flying characteristics. The theoretical analysis and experimental results show that the proposed micro flying head exhibits satisfying flying stability, with head-disk spacing less than 75nm, and carrying capacity exceeding 93mN.

A Novel Optical Fiber Displacement Measurement System

In order to meet the displacement measurement’s need for high precision and large measuring range, a novel design of optical fiber displacement system is proposed. Optical fiber is applied to the displacement measurement field with its simple structure, light weight, cheap cost and high precision. A displacement measurement model based on transmissive optical fiber is established, and theoretical calculation and simulation are conducted to verify the accuracy of the model. Displacement measuring experiments are completed and the results show that the transmissive optical fiber displacement measurement system has high measuring accuracy with the relative error less than 0.2% over a large range.

Experiments on Image Processing for Micro-Assembly

This paper introduces a micro-assembly system based on image processing and focuses on some key technologies. The system employed some orthogonal wavelet functions to filter images and the suitible filtering effects were obtained by Symlets wavelet basis. The auto-focusing method adopted in the micro-assembly system was the combination of coarse adjustment and fine adjustment. The resolution evaluation function for coarse adjustment was based on Krisch operator and the resolution evaluation function for fine one was based on high frequency component. Experimental results show that the focusing accuracy can reach ±4.0μm. A wavelet multiscale method based on variogram function was used in the edge detection, which can eliminate noise with more details retained. Generally the system can meet the requirements of micro-assembly.

Dynamic Characteristics Test of a Bearing Micro Workbench Used for Fiber Measurement

Dynamic characteristics of a bearing micro workbench are very important in the optical fiber measurement. A quantitative analysis method used for measuring the modal frequency and damping rate of the micro workbench is studied. A parameter identification method based on modal analysis is proposed. On the basis of it, a test system used for measuring the micro workbench impulse response is put up. By making use of the impulse excitation that is generated by the instantaneous change of the surface airflow, the micro bench impulse response curve is obtained. In order to improve the signal-to-noise ratio, a series of methods are utilized, such as precise trigger sampling and superposed average of multi-period data. Experimental results show that the micro workbench has a high modal frequency and a suitable damping rate, which meets the needs of the fiber measurement.

Research on control scheme in high-density multiwavelength optical disc mastering

In order to meet the development requirements of high density optical disc mastering, a control scheme of high-density multi-wavelength optical disc mastering by using the embedded architecture with the DSP as processor and CPLD as the logic path was supplied. A initial study on next generation ultra-high density mastering system was conducted and two level positioning technique and air-floating plus PZT aided focus technique are applied into the control system. The results of experiments show that the scheme is feasible, and the setups for optical disc mastering can meet the requirements.

Study on lateral dual-element electron tunneling accelerometer

Electron tunneling accelerometer has the advantages of high precision, small volume, low consumption and so on. This paper introduces the design on a lateral dual-element Electron Tunneling Accelerometer. The model, structure design, parameters test and fabrication process are provided in detail. The results of analysis and simulation show that the working frequency of sensor could be up to 2 kHz.

New control scheme in high density optical disk mastering system

The research of high density optical storage system leads to the high density of tracks and pits of the disc. The track pitch of high density optical storage system is much more narrow than that of ordinary optical disc such as DVD. The first step in the production process of both pre-record data and recordable optical discs is mastering. Thus in the high density optical storage system the stable and accurate mastering performance is of greatest importance. This paper presents a control scheme that provides fast, accurate and stable mastering performance. Because of the high density of the track on the optical disc, the conventional control of mastering scheme is unfit for good mastering performance. In this paper we review the development of optical storage system and analyze the problems that may arise when the conventional control scheme is applied to the high density optical disc mastering system. In the proposed scheme, a new tentative control system is designed. The performance of the proposed tentative control scheme is shown by experiments in the high density optical disc mastering system.

Development of real-time method to measure SIL-DISK spacing for super-low-flying system

The advanced data storage technology is important to information era. Among all sorts of solutions of high-density storage, near field optical disc technology (NFOD) is high speed and mass storage technology with excellent aptitude and future, and it is the focus of data storage research field in the pioneer technology. Today the research institutes all over the world are speeding their research on NFOD. By using the techniques of solid immersion lens (SIL) and super-low-flying system, it can achieve not only super-high recording density that can be much more higher than traditional optical disks but also the hard disks. In order to improving near-field coupling efficiency of SIL-TO-DISK, the SIL must keep sub micron flying height from the disk, so it is necessary to discuss the research process of real time method to measure SIL-TO-DISK for super-low-flying system. This paper analyses technique foundation and characteristc and its key problem for the flying height measurement, the paper studies several practicing plan of real time measure the clearance even when the SIL-DISK spacing is down to nanometer level for example, relative light intensity method, the capacitance displacement sensors, effective refractive index method for frustrated total reflection, and compare the characteristic and precision of those approach.

Measurement of dynamic properties of optical disk cluster drive using virtual instruments

Optical Disk Cluster (ODC) drive is the key component of ultra-large capacity optical storage system. The principle of ODC drive is introduced. The measurement and analysis system of dynamic properties of ODC is developed using graphical programming language, LabVIEW, the best software platform of virtual Instruments. The vibration characteristic of ODC is studied. The experiments show that the main reasons of ODC vibration are shaft eccentricity, disalignment of shaft, and inclination of optical disk. As the result, the methods of reducing vibration of optical disk are presented, which can be used to optimizing design of ODC.

Design of alignment and positioning structure in huge-capacity optical storage system

In order to meet the development requirements of high density, high capacity and high integration in the field of optical storage, a new scheme for optical recording system is supplied in this paper. At the same time the methods about disc alignment, position and clamping are discussed in details. The principle of flexure hinge is adopted. The results of experiments show that the scheme is feasible, and the setups for optical discs can meet the requirements.