To achieve 50nm flying height and accuracy tracking motion, it is essential to reduce the whole size of optical flying head (OFH) to improve mechanical and optical performance. With a view to the practical applicability, a novel integrated OFH based on the combination of SIL and objective lens (OL) is proposed, which possesses both high optical performance and reasonable tolerance in assembly. In addition, the fabrication process of this OFH is illustrated in detail. Finally, the main parameters of ABS for OFH slider are presented by means of numerical simulation. The simulation result demonstrates that the flying height of the integrated OFH slider can keep stable from 43nm to 44nm at different radium of optical disk, which can yield high signal/noise ratio optical signal during the read/write motion in near field recording (NFR) system.
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.
The vibration signal in the nature of singularity is always caused by mechanical fault of equipment. It is important to recognize the signal singularity correctly for mechanical fault diagnosis. The complex Hermitian wavelet is constructed by means of the first and the second derivatives of the Gaussian function to detect signal signularities. The Hermitian wavelet has a real Fourier transform that will not mix the signal phase with its filter phase, and its real part and imginary part have less oscillation than Morlet wavelet, so that the convolution operation can be process with fewer number of data points and the signal singularity will not be smeared. The time-scale amplitude plot and phase plot based on Hermitian wavelet are presented to detect signal singularities. A successful application has been obtained in diagnosis of large air compressor gearbox. According to the singularities extracted from amplitude plot and phase plot of gearbox vibration signals, it is obvious that there existed impact rub fault that caused intense vibration in the gearbox. After justified maintenance the compressor gearbox runs smoothly in a good condition.
KEYWORDS: Capacitance, Near field, Data storage, Sensors, Near field optics, Reflection, Time metrology, Refractive index, Optical discs, Optical testing
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.
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.
KEYWORDS: Optical storage, Control systems, Optical discs, Digital video discs, Compact discs, Optical tracking, Computing systems, Control systems design, Lithium, Computer networks
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.
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.
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