Browsing by Author "Peng, C. Y."

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An optical lever approach to photodetector measurements of the pickup-head flying height in an optical disk drive
(2006-08-01)
Hsiao, C. C.
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Peng, C. Y.
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Liu, T. S.
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機械工程學系
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Department of Mechanical Engineering
In order to increase the storage capacity and the density of near-field optical disk drives, a flying pickup-head has to allow a slider to fly at a stable height above the disk surface with the use of near-field optics. Since both the precision of the track pitch and the flying height are of a nanometre scale, it is necessary to increase the motion accuracy of the pickup- head. In this study, a piezoelectric bender is used as an actuator of the pickup- head, and two quadrant photodetectors are used to sense the pickup- head displacement and the rotating disk deformation. Based on an optical lever method that magnifies a small displacement, the flying height variation of the pickup- head above the disk is measured. Further results show that using the proposed measurement method in the real-time control of flying height is feasible.
Orthorhombic BiFeO3
(2012-12-14)
Yang, J. C.
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He, Q.
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Suresha, S. J.
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Kuo, C. Y.
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Peng, C. Y.
A new orthorhombic phase of the multiferroic BiFeO3 has been created via strain engineering by growing it on a NdScO3(110)(o) substrate. The tensile-strained orthorhombic BiFeO3 phase is ferroelectric and antiferromagnetic at room temperature. A combination of nonlinear optical second harmonic generation and piezoresponse force microscopy revealed that the ferroelectric polarization in the orthorhombic phase is along the in-plane < 110 >(pc) directions. In addition, the corresponding rotation of the antiferromagnetic axis in this new phase was observed using x-ray linear dichroism. DOI: 10.1103/PhysRevLett.109.247606